TY - THES A1 - Meir [geb. Rother], Juliane T1 - Influence of oncolytic vaccinia viruses on metastases of human and murine tumors T1 - Einfluss von onkolytischen Vaccinia Viren auf Metastasen von humanen und murinen Tumoren N2 - Cancer is one of the leading causes of death. 90% of all deaths are caused by the effects of metastases. It is of major importance to successfully treat the primary tumor and metastases. Tumors and metastases often differ in their properties and therefore, treatment is not always successful. In contrast, those therapeutic agents can even promote formation and growth of metastases. Hence, it is indispensable to find treatment options for metastatic disease. One promising candidate represents the oncolytic virus therapy with vaccinia viruses. The aim of this work was to analyze two cell lines regarding their metastatic abilities and to investigate whether oncolytic vaccinia viruses are useful therapy options. The cell lines used were the human cervical cancer cell line C33A implanted into immune-compromised mice and the murine melanoma cell line B16F10, implanted into immune-competent mice. The initial point of the investigations was the observation of enlarged lumbar und renal lymph nodes in C33A tumor-bearing mice 35 days post implantation of C33A cells subcutaneously into immune-compromised nude mice. Subsequently, the presence of human cells in enlarged lymph nodes was demonstrated by RT-PCR. To facilitate the monitoring of cancer cell spreading, the gene encoding for RFP was inserted into the genome of C33A cells. In cell culture experiments, it was possible to demonstrate that this insertion did not negatively affect the susceptibility of the cells to virus infection, replication and virus-mediated cell lysis. The analysis of the metastatic process in a xenografted mouse model revealed the continuous progression of lumbar (LN) and renal (RN) lymph node metastasis after C33A-RFP tumor cell implantation. The lymph node volume and the amount of RFP-positive LNs and RNs was increasing from week to week in accordance with the gain of the primary tumor volume. Moreover, the metastatic spread of cancer cells in lymph vessels between lumbar and renal lymph nodes was visualized. Additionally, the haematogenous way of cancer cell migration was demonstrated by RFP positive cancer cells in blood vessels. The haematogenous route of spreading was confirmed by detecting micrometastases in lungs of tumor bearing mice. The next step was to investigate whether the recombinant oncolytic vaccinia virus GLV-1h68 is a suitable candidate to cure the primary tumor and metastases. Therefore, GLV-1h68 was systemically injected into C33A-RFP tumor bearing mice 21 days after tumor cell implantation. It was demonstrated that the volume of the primary tumor was drastically reduced, and the volume and the amount of RFP positive lumbar and renal lymph nodes were significantly decreasing compared to the untreated control group. Subsequently, this process was analyzed further by investigating the colonization pattern in the C33A-RFP model. It was shown that first the primary tumor was colonized with highest detectable virus levels, followed by LN and RN lymph nodes. Histological analyses revealed the proliferative status of tumor cells in the tumor and lymph nodes, the amount of different immune cell populations and the vascular permeability in primary tumors and lymph nodes having an influence on the colonization pattern of the virus. Whereby, the vascular permeability seems to have a crucial impact on the preferential colonization of tumors compared to lymph node metastases in this tumor model. C33A turned out to be a useful model to study the formation and therapy of metastases. However, a metastatic model in which the influence of the immune system on tumors and especially on tumor therapy can be analyzed would be preferable. Therefore, the aim of the second part was to establish a syngeneic metastatic mouse model. Accordingly, the murine melanoma cell line B16F10 was analyzed in immunocompetent mice. First, the highly attenuated GLV 1h68 virus was compared to its parental strain LIVP 1.1.1 concerning infection, replication and cell lysis efficacy in cell culture. LIVP 1.1.1 was more efficient than GLV-1h68 and was subsequently used for following mouse studies. Comparative studies were performed, comparing two different implantation sites of the tumor cells, subcutaneously and footpad, and two different mouse strains, FoxN1 nude and C57BL/6 mice. Implantation into the footpad led to a higher metastatic burden in lymph nodes compared to the subcutaneous implantation site. Finally, the model of choice was the implantation of B16F10 into the footpad of immune-competent C57BL/6 mice. Furthermore, it was inevitable to deliver the virus as efficient as possible to the tumor and metastases. Comparison of two different injection routes, intravenously and intratumorally, revealed, that the optimal injection route was intratumorally. In summary, the murine B16F10 model is a promising model to study the effects of the immune system on vaccinia virus mediated therapy of primary tumors and metastases. N2 - Weltweit ist Krebs eine der häufigsten Todesursachen des Menschen. Allerdings wird angenommen, dass ca. 90 % dieser Todesfälle nicht auf den Primärtumor zurückzuführen sind, sondern durch den direkten und indirekten Einfluss von Metastasen verursacht werden. Deshalb ist es wichtig, eine Therapieform zu wählen, die sowohl den Primärtumor als auch Metastasen bekämpft. Bei den derzeit eingesetzten Behandlungsmethoden für Metastasen handelt es sich weitestgehend um die gleichen Therapieformen die auch zur Bekämpfung des Primärtumors eingesetzt werden. Allerdings unterscheiden sich Primärtumor und Metastasen häufig in ihren Eigenschaften, weshalb die Therapie oft keinen Erfolg bei Metastasen zeigt und im schlimmsten Fall sogar deren Neubildung und Wachstum fördern kann. Deswegen ist es von immenser Bedeutung, neue Therapieformen zu entwickeln, die speziell auch auf die Wirksamkeit gegen Metastasen zugeschnitten sind. Eine vielversprechende Möglichkeit hierfür stellt die onkolytische Virustherapie dar. Das Hauptziel dieser Arbeit war es, zwei verschiedene Tumorzelllinien hinsichtlich ihrer metastatischen Fähigkeiten zu untersuchen und anschließend zu überprüfen, ob onkolytische Vaccinia Viren zur Therapie dieser Metastasen beitragen können. Bei den hierfür untersuchten Zelllinien handelte es sich um die menschliche Zervixkarzinomzelllinie C33A, implantiert in immunsupprimierte Mäuse und um die murine Melanomzelllinie B16F10, implantiert in immunkompetente Mäuse. Ausgangspunkt der Untersuchungen im ersten Teil der Arbeit, bildete die Beobachtung, dass nach der subkutanen Implantation von C33A-Zellen in die abdominale Flanke von immunsupprimierten Nacktmäusen die lumbalen und renalen Lymphknoten der tumortragenden Mäuse vergrößert waren. Die Untersuchung dieser vergrößerten Lymphknoten mittels RT-PCR, unter zu Hilfenahme von spezifischen Primern für humanes β-Aktin, wies tatsächlich humane Zellen in allen lumbalen und der Hälfte der renalen Lymphknoten nach. Darum sollte im nächsten Schritt das metastatische Verhalten dieser Zellen genauer untersucht werden. Hierfür wurde mittels lentiviraler Transduktion, das für das rotfluoreszierende Protein kodierende Gen in C33A-Zellen integriert. In Zellkulturexperimenten konnte nachgewiesen werden, dass die Insertion sich nicht negativ auf die Infektion, Replikation und Zelllyse der Viren auswirkte. Anschließende Mausexperimente zeigten den Verlauf der Metastasierung der lumbalen und renalen Lymphknoten. Sowohl das Volumen als auch die Anzahl an RFP positiven Lymphknoten nahm nach Implantation von Woche zu Woche zu und korrelierte mit der Zunahme des Primärtumorvolumens. Darüber hinaus konnte die Migration der Tumorzellen in Lymphgefäßen zwischen dem lumbalen und renalem Lymphknotenpaar mit Hilfe der Fluoreszenzmikroskopie sichtbar gemacht werden. Zusätzlich konnte die Metastasierung über die Blutbahn nachgewiesen werden, da sich RFP positive Zellen in dem Blutgefäß neben dem Lymphgefäß, das die lumbalen und renalen Lymphknoten miteinander verbindet, befanden. Die hämatogene Verbreitung wurde auch dadurch bestätigt, dass in den Lungen der tumortragenden Mäuse Mikrometastasen detektiert werden konnten. Im nächsten Schritt wurde untersucht, ob das rekombinante Vaccinia Virus GLV-1h68 in der Lage ist, nicht nur den primären Tumor zu bekämpfen, sondern auch Metastasen. Dafür wurde tumortragenden Mäusen systemisch eine einzelne Dosis GLV-1h68 21 Tage nach Tumorzellimplantation injiziert. Daraufhin reduzierte sich nicht nur das Volumen des Primärtumors innerhalb von weiteren 21 Tagen auf die Ausgangsgröße, sondern auch das Volumen und die Anzahl der RFP positiven lumbalen und renalen Lymphknoten nahm ab, im Vergleich zur unbehandelten Kontrolle. Die Analyse der Kolonisierungsdynamik von Primärtumor und Metastasen durch GLV 1h68 zeigte, dass zuerst der Primärtumor kolonisiert wurde, gefolgt von LN und RN. Des Weiteren war der virale Titer in Tumoren zu jedem Zeitpunkt höher als in den metastasierten Lymphknoten. Histologische Untersuchungen des tumorösen Gewebes zeigten, dass der proliferative Status der Tumorzellen, die Menge verschiedener Immunzellpopulationen und die vaskuläre Permeabilität einen Einfluss auf die Kolonisierung durch GLV-1h68 haben. Dabei wird angenommen, dass vor allem die vaskuläre Permeabilität den größten Einfluss auf die Kolonisierungsreihenfolge hat. Zusammenfassend kann gesagt werden, dass C33A ein hilfreiches Model ist, um die Bildung von Metastasen sowie die onkolytische Virustherapie dieser in einem immunsupprimierten Model zu untersuchen. Aus klinischer Sicht allerdings wäre es wünschenswert, ein Model zu haben, in dem auch der Einfluss des Immunsystems auf die Tumortherapie untersucht werden kann. Deswegen war das Ziel im zweiten Teil der Arbeit die murine Melanomazelllinie B16F10 im immunkompetenten Mausmodell als metastatisches System zu etablieren. Als erstes wurde in Zellkulturexperimenten überprüft, wie geeignet GLV-1h68 ist, um die murinen Zellen zu infizieren, in ihnen zu replizieren und sie anschließend zu lysieren und mit dem parentalen Virus LIVP 1.1.1 verglichen. Dabei stellte sich heraus, dass LIVP 1.1.1 effizienter und geeigneter ist als GLV-1h68. Deswegen wurde in weiteren Versuchen das parentale Virus LIVP 1.1.1 verwendet. Bevor diese Experimente durchgeführt wurden, wurden Studien durchgeführt, bei denen 2 verschiedene Implantationsstellen, subkutan und in die Fußsohle, und 2 verschiedene Mausstämme, FoxN1 nude und C57BL/6, verglichen wurden. Dabei stellte sich heraus, dass nach Implantation in die Fußsohle mehr Lymphknotenmetastasen entstanden als nach subkutaner Implantation. Im weiteren Verlauf wurde die Implantation von B16F10 Zellen in die Fußsohle von C57BL/6 Mäusen bevorzugt, um eine verlässliches Metastasenmodel zu generieren. Im Folgenden wurden zwei verschiedene Injektionswege untersucht, intravenös und intratumoral, wobei sich die intratumoral Injektion als geeigneter erwies, um effizient so viel Virus wie möglich in Tumore und Metastasen zu bringen. Generell handelt es sich hierbei um ein geeignetes Model, um die Wirkungen des Immunsystems auf Vaccinia Virus vermittelte Therapie von Primärtumor und Lymphknotenmetastasen zu untersuchen. KW - Krebs KW - Metastase KW - Vaccinia-Virus KW - onkolytische Virustherapie KW - oncolytic virus therapy Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-118530 ER - TY - THES A1 - Kober, Christina T1 - Characterization of Murine GL261 Glioma Models for Oncolytic Vaccinia Virus Therapy T1 - Charakterisierung onkolytischer Vaccinia Virus Therapie in murinen Gliommodellen N2 - Glioblastoma multiforme (GBM) is one of the most frequent and malignant forms of brain cancer in adults. The prognosis is poor with a median survival time of 12-15 months. There is a broad range of alternative treatment options studied in preclinical and clinical trials for GBM. One alternative treatment option is oncolytic virotherapy, defined as the use of replication‐competent viruses that selectively infect and destroy cancer cells while leaving, non‐transformed cells unharmed. Vaccinia virus (VACV) is one favorable candidate. Although oncolytic viruses can kill tumor cells grown in vitro with high efficiency, they often exhibit reduced replication capacity in vivo suggesting that physiological aspects of the tumor microenvironment decrease the virus’ therapeutic potential. The percentage and composition of immune cells varies between cancer types and patients and is investigated as a biomarker in several studies. Making oncolytic virotherapy successful for GBM, it is necessary to understand the individual tumor biology, the interaction with the microenvironment and immune system. It was demonstrated that the attenuated VACV wild-type (wt) isolate LIVP 1.1.1 replicate and lyse the murine GL261 glioma cell line in vitro. In the following, the replication efficacy was characterized in a comparative approach in vivo. Immunocompetent C57BL/6 (wt) mice and immunodeficient mouse strains of different genetic background C57BL/6 athymic and Balb/c athymic mice were used. In addition, subcutaneous and intracranial locations were compared. The results revealed viral replication exclusively in Balb/c athymic mice with subcutaneous tumors but in none of the other models. In the following, the tumor microenvironment of the subcutaneous tumor models at the time of infection was performed. The study showed that implantation of the same tumor cells in different mouse strains resulted in a different tumor microenvironment with a distinct composition of immune cells. Highest differences were detected between immunodeficient and immunocompetent mice. The study showed major differences in the expression of MHCII with strongest expression in C57BL/6 wt and weakest in Balb/c athymic tumors. In the following, the influence of the phenotypic change associated with the upregulation of MHCII on GL261 tumor cells on viral replication was analyzed. Comparison of C57BL/6 wt and C57BL/6 IFN-γ knockout mice revealed endogenous IFN-γ levels to upregulate MHCII on GL261 tumor cells and to reduce viral replication in C57BL/6 wt mice. Analysis of single cell suspensions of tumor homogenates of C57BL/6 and Balb/c athymic mice showed that the IFN-γ-mediated anti-tumor effect was a reversible effect. Furthermore, reasons for inhibition of virus replication in orthotopic glioma models were elucidated. By immunohistochemical analysis it was shown that intratumoral amounts of Iba1+ microglia and GFAP+ astrocytes in Gl261 gliomas was independent from intratumoral VACV injection. Based on these findings virus infection in glioma, microglia and astrocytes was compared and analyzed in cell culture. In contrast to the GL261 glioma cells, replication was barely detectable in BV-2 microglia and IMA2.1 astrocytic cells. Co-culture experiments revealed that microglia compete for virus uptake in cell culture. It was further shown that BV-2 cells showed apoptotic characteristics after VACV infection while GL261 cells showed signs of necrotic cell death. Additionally, in BV-2 cells with M1-phenotype a further reduction of viral replication and inhibition of cell lysis was detected. Infection of IMA 2.1 cells was independent of the M1/M2-phenotype. Application of BV-2 microglia with M1-phenotype onto organotypic slice cultures with implanted GL261 tumors resulted in reduced infection of BV-2 cells with LIVP 1.1.1, whereas GL261 cells were significantly infected. Taken together, the analyzed GL261 tumors were imprinted by the immunologic and genetic background in which they grow. The experimental approach applied in this thesis can be used as suitable model which reflects the principles of personalized medicine In an additional project, based on gene expression data and bioinformatic analyses, the biological role and function of the anti-apoptotic factor AVEN was analyzed with regard to oncolytic VACV therapy. Besides a comparison of the replication efficacy of GLV-1h68 and VACV-mediated cell killing of four human tumor cell lines, it was shown that AVEN was expressed in all analyzed cells. Further, shown for HT-29 and 1936-MEL, the knockdown of AVEN by siRNA in cell culture resulted in an increase of apoptotic characteristics and a decrease of VACV infection. These findings provide essential insights for future virus development. N2 - Glioblastoma multiforme (GBM) ist einer der häufigsten und bösartigsten Hirntumoren im Erwachsenenalter. Die Prognose für GBM ist mit einer Überlebenszeit von 12-15 Monaten sehr schlecht. Eine alternative Behandlungsmöglichkeit stellt die onkolytische Virustherapie dar. Ein vielversprechender Kandidat ist das Vaccinia-Virus. Die große Diskrepanz zwischen der onkolytischen Effektivität in Zellkultur und den Ergebnissen im Mausmodell ist oftmals auf physiologische Komponenten im Tumor-Mikromilieu zurückzuführen. Die Zusammensetzung von Immunzellen im Mikromilieu variiert zwischen verschiedenen Krebsarten und Patienten und wird als Biomarker angewendet. Um eine erfolgreiche Virustherapie für GBM zu etablieren, wird ein umfangreiches Verständnis der Tumorbiologie, des Tumormikromilieus und des Immunsystems vorausgesetzt. Es wurde gezeigt, dass LIVP 1.1.1, ein attenuiertes wildtypisches VACV-Isolat, in der murinen GL261 Gliom-Zelllinie repliziert und zum Absterben der Zellen führt. Daraufhin wurde die Replikationseffizienz von LIVP 1.1.1 durch einen vergleichenden Ansatz in murinen GL261-Gliomen im Mausmodell untersucht. Es wurden immunkompetente C57BL/6-wildtypische (wt) Mäuse und immundefiziente Mausstämme mit unterschiedlichem genetischem Hintergrund, C57BL/6 athymisch und Balb/c athymisch, verwendet. Zudem wurden unterschiedliche Tumor-Lokalisationen, subkutan und intrakranial analysiert. Ausschließlich im subkutanen Tumormodell der Balb/c athymischen Mäuse fand eine effektive Replikation der Viren statt. Eine detaillierte Charakterisierung des Mikromilieus zum Zeitpunkt der Infektion zeigte, dass die Implantation derselben Tumorzellen in unterschiedliche Mausstämme zur Entwicklung eines unterschiedlichen Tumormikromilieus und einer variierenden Zusammensetzung von Immunzellen führt. Die C57BL/6-wt-Mäuse wiesen eine starke proinflammatorische Signatur auf. Des Weiteren zeigte die Studie signifikante Unterschiede in der MHCII-Expression: Die prominenteste Expression wurde in C57BL/6-wt-Mäusen detektiert. Im weiteren Verlauf wurde analysiert, wodurch die phänotypischen Veränderungen in den GL261-Zellen, verbunden mit der Hochregulierung von MHCII ausgelöst wurden und welche Konsequenzen dies für die virale Infektion dieser Zellen hat. Durch einen direkten Vergleich von C57BL/6-wt-Mäusen und C57BL/6-IFN-γ-Knockout Mäusen konnte IFN-γ als verantwortlicher Faktor im Tumormikromilieu identifiziert werden, welcher für die Reduktion des Virustiters und für die Hochregulierung von MHCII in den C57BL/6-wt-Mäusen verantwortlich ist. Der durch endogenes IFN-γ ausgelöste anti-virale Effekt war reversibel. Des Weiteren wurden Gründe für die Hemmung der viralen Replikation in den orthotopen Gliom-Modellen aufgeklärt. Durch immunhistochemische Analysen von Mikroglia und Astrozyten konnte gezeigt werden, dass die intratumorale Menge und Verteilung der Gliazellen in diesen Tumoren unabhängig von der Virus-Applikation war. Gliomzellen, Mikroglia und Astrozyten, wurden daraufhin untersucht. Im Vergleich zur starken Replikation in GL261-Zellen, ließen BV-2-Mikroglia und IMA 2.1-Astrozyten, nur eine sehr schwache Replikation von LIVP 1.1.1 zu. Ko-Kultivierungsversuche wiesen darauf hin, dass Mikroglia um die Aufnahme der Viruspartikel mit den Tumorzellen konkurrieren. Es wurde gezeigt, dass das LIVP 1.1.1 unterschiedliche Eigenschaften des Zelltods in den Zellen auslösen kann. BV-2 wiesen verstärkte Charakteristika der Apoptose auf während in GL261-Zellen nekrotische Eigenschaften überwogen. In BV-2-Zellen mit M1-Phänotyp wurde eine weitere Reduktion der viralen Infektion festgestellt. Die Infektion von IMA-2.1-Zellen war unabhängig vom induzierten M1/M2 Phänotyp. Die Applikation von BV-2-Zellen mit M1-Phänotyp auf organotypische Schnittkulturen mit implantierten GL261-Tumoren resultierte in einer reduzierten Infektion der BV-2-Zellen und einer verstärkten Infektion der GL261-Zellen. Es wurde gezeigt, dass GL261-Tumore durch den immunologischen und genetischen Hintergrund der Umgebung geprägt wurden. Es wurde ein Modell entwickelt, welches das Prinzip der personalisierten Medizin widerspiegelt. In einem zusätzlichen Projekt wurde, basierend auf Genexpressionsdaten und bioinformatischer Auswertung, die biologische Funktion des anti-apoptotischen Faktors AVEN hinsichtlich der onkolytischen Virustherapie mit dem VACV GLV-1h68 analysiert. Für diese Studie wurden vier humane Zelllinien untersucht. Neben einem Vergleich der Replikationseffizienz des VACV GLV-1h68 und der VACV-vermittelten Zelllyse wurde gezeigt, dass AVEN, in allen untersuchten Zellen exprimiert wird. Am Beispiel von HT-29 und 1936-MEL wurde gezeigt, dass die Herunterregulierung von AVEN durch siRNA zu einer Erhöhung der apoptotischen Eigenschaften und Abnahme der VACV Infektion führt. Die Ergebnisse liefern wichtige Erkenntnisse für die Entwicklung zukünftiger genetisch veränderter VACV. KW - Krebs KW - Vaccinia-Virus KW - Glioblastom KW - Onkolytische Vaccinia Virustherapie KW - Mikroglia KW - Astrozyten KW - Oncolytic Vaccinia Virus Therapy Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-118556 ER - TY - THES A1 - Graver, Shannon T1 - Molecular and cellular cross talk between angiogenic, immune and DNA mismatch repair pathways T1 - Molekulare und zellulare Interaktion zwischen Angiogenese, DNA Fehlerreparatur (Mismatch Repair) und Immunologischen Signalwegen N2 - VEGF is a main driver of tumor angiogenesis, playing an important role not only in the formation of new blood vessels, but also acts as a factor for cell migration, proliferation, survival and apoptosis. Angiogenesis is a universal function shared by most solid tumors and its inhibition was thought to have the potential to work across a broad patient population. Clinical evidence has shown that inhibiting pathological angiogenesis only works in a subset of patients and the identification of those patients is an important step towards personalized cancer care. The first approved antiangiogenic therapy was bevacizumab (Avastin®), a monoclonal antibody targeting VEGF in solid tumors including CRC, BC, NSCLC, RCC and others. In addition to endothelial cells, VEGF receptors are present on a number of different cell types including tumor cells, monocytes and macrophages. The work presented in this thesis looked at the in vitro cellular changes in tumor cells and leukocytes in response to the inhibition of VEGF signaling with the use of bevacizumab. In the initial experiments, VEGF was induced by hypoxia in tumor cells to evaluate changes in survival, proliferation, migration and changes in gene or protein expression. There was a minimal direct response of VEGF inhibition in tumor cells that could be attributed to bevacizumab treatment, with minor variations in some of the cell lines screened but no uniform or specific response noted. MMR deficiency often results in microsatellite instability (MSI) in tumors, as opposed to microsatellite stable (MSS) tumors, and accounts for up to 15% of colorectal carcinomas (CRCs). It has been suggested in clinical data that MMR deficient tumors responded better to bevacizumab regimens, therefore further research used isogenic paired CRC tumor cell lines (MMR deficient and proficient). Furthermore, a DNA damaging agent was added to the treatment regimen, the topoisomerase inhibitor SN-38 (the active metabolite of irinotecan). Inhibiting VEGF using bevacizumab significantly inhibited the ability of MMR deficient tumor cells to form anchor dependent colonies, however conversely, bevacizumab treatment before damaging cells with SN-38, showed a significant increase in colony numbers. Moreover, VEGF inhibition by bevacizumab pretreatment also significantly increased the mutation fraction in MMR deficient cells as measured by transiently transfecting a dinucleotide repeat construct, suggesting VEGF signaling may have an intrinsic role in MMR deficient cells. A number of pathways were analyzed in addition to changes in gene expression profiles resulting in the identification of JNK as a possible VEGF targeted pathway. JUN expression was also reduced in these conditions reinforcing this hypothesis, however the intricate molecular mechanisms remain to be elucidated. In order to remain focused on the clinical application of the findings, it was noted that some cytokines were differentially regulated by bevacizumab between MMR proficient and deficient cells. Treatment regimens employed in vitro attempted to mimic the clinical setting by inducing DNA damage, then allowing cells to recover with or without VEGF using bevacizumab treatment. Inflammatory cytokines, CCL7 and CCL8, were found to have higher expression in the MMR deficient cell line with bevacizumab after DNA damage, therefore the cross talk via tumor derived factors to myeloid cells was analyzed. Gene expression changes in monocytes induced by tumor conditioned media showed CCL18 to be a bevacizumab regulated gene by MMR deficient cells and less so in MMR proficient cells. CCL18 has been described as a prognostic marker in gastric, colorectal and ovarian cancers, however the significance is dependent on tumor type. CCL18 primarily exerts its function on the adaptive immune system to trigger a TH2 response in T cells, but is also described to increase non-specific phagocytosis. The results of this study did show an increase in the phagocytic activity of macrophages in the presence of bevacizumab that was significantly more apparent in MMR deficient cells. Furthermore, after DNA damage MMR deficient cells treated with bevacizumab released a cytokine mix that induced monocyte migration in a bevacizumab dependent manner, showing a functional response with the combination of MMR deficiency and bevacizumab. In summary, the work in this thesis has shown evidence of immune cell modulation that is specific to MMR deficient tumor cells that may translate into a marker for the administration of bevacizumab in a clinical setting. VEGF ist ein zentraler Regulator der Tumor-Angiogenese, und spielt eine wichtige Rolle nicht nur in der Bildung von neuen Blutgefäßen, sondern ist auch für die Migration, Proliferation, das Überleben und Apoptose von Tumorzellen essentiell. Angiogenese ist eine der universellen Funktionen, welche das Wachstum der meisten soliden Tumoren charakterisiert. Eine der klassischen therapeutischen Ideen wurde auf der Basis entwickelt, dass die spezifische Hemmung der Angiogenese das Potenzial hat in einer breiten Patientenpopulation einen klinischen Effekt zu zeigen. Die klinische Erfahrung und Anwendung hat jedoch gezeigt, dass die Hemmung der pathologischen Angiogenese nur in einem Teil der Patienten einen therapeutischen Nutzen aufweist. Somit stellt die Identifikation derjenigen Patienten, welche von der anti-angiogenen Therapie profitieren, einen wichtiger Schritt zur personalisierten Krebsbehandlung dar. Die erste zugelassene antiangiogene Therapie war Bevacizumab (Avastin®), ein monoklonaler Antikörper gegen VEGF, welcher unter anderem in soliden Tumoren wie CRC, BC, nicht-kleinzelligem Lungenkrebs (NSCLC) und dem Nierenzellkarzinom angewandt wird. VEGF-Rezeptoren befinden sich nicht nur auf Endothelzellen, sondern sind auch auf einer Anzahl von verschiedenen Zelltypen, einschließlich Tumorzellen, Monozyten und Makrophagen nachweisbar. Die in dieser Arbeit vorgestellten Ergebnisse befassen sich mit den zellulären Veränderungen an Tumorzellen und Leukozyten als Reaktion auf die Hemmung der VEGF-Signalkaskade durch Bevacizumab in-vitro. In den Initialen Experimenten wurde VEGF durch Hypoxie in Tumorzellen induziert und Veränderungen der Überlebensrate, der Proliferation, Migration als auch in der Gen- oder Protein-Expression gemessen. Es konnte eine minimale direkte Reaktion der VEGF-Hemmung auf Tumorzellen beobachtet werden, welche auf die Bevacizumab Behandlung zurückgeführt werden könnte. Es zeigten sich aber auch geringfügige Abweichungen in einigen der verwendeten Zellinien, die keine einheitliche Interpretation erlauben oder auf eine uniformelle Reaktion hinweisen würden. Das phänotypische Korrelat einer „Mismatch“ Reparatur (MMR)-Defizienz ist die Mikrosatelliteninstabilität im Gegensatz zu mikrosatellitenstabilen Tumoren und findet sich bei bis zu 15% der kolorektalen Karzinomen (CRC) wieder. Klinischen Daten deuten daraufhin, dass Bevacizumab besser in MMR-defizienten Tumoren wirkt. Daher wurden die weiteren Untersuchungen in gepaarten MMR stabilen und MMR instabilen CRC-Tumorzelllinien (MMR defizient und kompetent) durchgeführt. Weiterhin wurde ein DNA-schädigendes Agens, SN-38, ein Topoisomerase-Inhibitor (der aktive Metabolit von Irinotecan) dem Behandlungsschema zugefügt. Es zeigte sich, dass die Hemmung von VEGF mittels Bevacizumab die Fähigkeit der MMR defizienten Tumorzellen Kolonien zu bilden signifikant inhibiert. Im Gegensatz dazu, hatte die Behandlung von Bevacizumab vor der Zugabe des DNA schädigenden Agens zu einer vermehrten Kolonienzahl geführt. Außerdem erhöhte die Vorbehandlung mit Bevacizumab deutlich die Mutationsrate in MMR-defizienten Zellen, was durch die transiente Transfektion eines Dinukleotid-Repeat-Konstrukts nachgewiesen werden konnte. Dies deutete darauf hin, dass VEGF eine intrinsische Rolle in der Signalkaskade des MMR-Systems haben könnte. Deshalb wurde eine Anzahl von Signalalkaskaden zusätzlich zu Veränderungen von Genexpressionsprofilen untersucht und JNK als mögliche Verbindungsstelle der beiden Signalkaskaden, VEGF und MMR, identifiziert. Diese Hypothese wurde zusätzlich unterstützt durch die Tatsache, dass die JUN Expression unter diesen experimentellen Bedingungen reduziert war. Die Aufklärung der komplexen molekularen Mechanismen der potentiellen Interaktion bleibt zukünftigen Untersuchungen vorbehalten. In Hinblick auf die klinische Konsequenz der erhaltenen Ergebnisse war es auffällig, dass einige Zytokine durch Bevacizumab in den MMR defizienten Zellen im Gegensatz zu den MMR kompetenten Zellen unterschiedlich reguliert wurden. Die in-vitro verwendeten Behandlungsschemata waren den klinisch zur Anwendung kommenden Protokollen nachempfunden. Zuerst wurde ein DNA-Schaden gesetzt, und den Zellen ermöglicht, sich mit oder ohne Bevacizumab zu erholen. Es konnte gezeigt werden, dass die inflammatorischen Zytokine CCL7 und CCL8 eine höhere Expression in der MMR-defiziente Zelllinie in Kombination mit Bevacizumab aufweisen. Daher wurde ein möglicher Crosstalk zwischen von Tumorzellen sezernierten Faktoren und myeloischen Zellen weiter verfolgt. Veränderungen der Genexpression in Monozyten durch Tumorzell- konditionierte Medien zeigte CCL18 als ein Bevacizumab reguliertes Gen in MMR-defizienten Zellen, aber nicht in MMR kompetenten Zellen. CCL18 übt seine Funktion primär im adaptiven Immunsystems aus um eine TH2-Antwort in T-Zellen auszulösen Ausserdem wird eine Erhöhung der nicht-spezifische Phagozytose als weitere Funktion beschrieben. CCL18 wurde bereits als prognostischer Marker in Magen-, Dickdarm- und Eierstockkrebsarten beschrieben; die klinische Bedeutung ist jedoch abhängig von Tumortyp. Die Ergebnisse dieser Arbeit zeigen, dass eine Erhöhung der phagozytischen Aktivität von Makrophagen in Gegenwart von Bevacizumab wesentlich deutlicher in MMR-defizienten Zellen ausgeprägt war. Weiterhin wurde gefunden, dass nach DNA-Schädigung in Bevacizumab behandelten MMR-defizienten Zellen Zytokine freigesetzt werden, welche eine Monozytenmigration in einer Bevacizumab-abhängigen Weise induzieren. Dies weist auf eine funktionelle Interaktion von MMR-Defizienz und Bevacizumab hin. Zusätzlich zeigen die Ergebnisse dieser Arbeit eine Immunzellmodulation, die spezifisch für Mismatch-Reparatur defiziente Tumorzellen ist und in der klinischen Praxis als Marker für die Verabreichung von Bevacizumab verwendet werden könnte. N2 - VEGF ist ein zentraler Regulator der Tumor-Angiogenese, und spielt eine wichtige Rolle nicht nur in der Bildung von neuen Blutgefäßen, sondern ist auch für die Migration, Proliferation, das Überleben und Apoptose von Tumorzellen essentiell. Angiogenese ist eine der universellen Funktionen, welche das Wachstum der meisten soliden Tumoren charakterisiert. Eine der klassischen therapeutischen Ideen wurde auf der Basis entwickelt, dass die spezifische Hemmung der Angiogenese das Potenzial hat in einer breiten Patientenpopulation einen klinischen Effekt zu zeigen. Die klinische Erfahrung und Anwendung hat jedoch gezeigt, dass die Hemmung der pathologischen Angiogenese nur in einem Teil der Patienten einen therapeutischen Nutzen aufweist. Somit stellt die Identifikation derjenigen Patienten, welche von der anti-angiogenen Therapie profitieren, einen wichtiger Schritt zur personalisierten Krebsbehandlung dar. Die erste zugelassene antiangiogene Therapie war Bevacizumab (Avastin®), ein monoklonaler Antikörper gegen VEGF, welcher unter anderem in soliden Tumoren wie CRC, BC, nicht-kleinzelligem Lungenkrebs (NSCLC) und dem Nierenzellkarzinom angewandt wird. VEGF-Rezeptoren befinden sich nicht nur auf Endothelzellen, sondern sind auch auf einer Anzahl von verschiedenen Zelltypen, einschließlich Tumorzellen, Monozyten und Makrophagen nachweisbar. Die in dieser Arbeit vorgestellten Ergebnisse befassen sich mit den zellulären Veränderungen an Tumorzellen und Leukozyten als Reaktion auf die Hemmung der VEGF-Signalkaskade durch Bevacizumab in-vitro. In den Initialen Experimenten wurde VEGF durch Hypoxie in Tumorzellen induziert und Veränderungen der Überlebensrate, der Proliferation, Migration als auch in der Gen- oder Protein-Expression gemessen. Es konnte eine minimale direkte Reaktion der VEGF-Hemmung auf Tumorzellen beobachtet werden, welche auf die Bevacizumab Behandlung zurückgeführt werden könnte. Es zeigten sich aber auch geringfügige Abweichungen in einigen der verwendeten Zellinien, die keine einheitliche Interpretation erlauben oder auf eine uniformelle Reaktion hinweisen würden. Das phänotypische Korrelat einer „Mismatch“ Reparatur (MMR)-Defizienz ist die Mikrosatelliteninstabilität im Gegensatz zu mikrosatellitenstabilen Tumoren und findet sich bei bis zu 15% der kolorektalen Karzinomen (CRC) wieder. Klinischen Daten deuten daraufhin, dass Bevacizumab besser in MMR-defizienten Tumoren wirkt. Daher wurden die weiteren Untersuchungen in gepaarten MMR stabilen und MMR instabilen CRC-Tumorzelllinien (MMR defizient und kompetent) durchgeführt. Weiterhin wurde ein DNA-schädigendes Agens, SN-38, ein Topoisomerase-Inhibitor (der aktive Metabolit von Irinotecan) dem Behandlungsschema zugefügt. Es zeigte sich, dass die Hemmung von VEGF mittels Bevacizumab die Fähigkeit der MMR defizienten Tumorzellen Kolonien zu bilden signifikant inhibiert. Im Gegensatz dazu, hatte die Behandlung von Bevacizumab vor der Zugabe des DNA schädigenden Agens zu einer vermehrten Kolonienzahl geführt. Außerdem erhöhte die Vorbehandlung mit Bevacizumab deutlich die Mutationsrate in MMR-defizienten Zellen, was durch die transiente Transfektion eines Dinukleotid-Repeat-Konstrukts nachgewiesen werden konnte. Dies deutete darauf hin, dass VEGF eine intrinsische Rolle in der Signalkaskade des MMR-Systems haben könnte. Deshalb wurde eine Anzahl von Signalalkaskaden zusätzlich zu Veränderungen von Genexpressionsprofilen untersucht und JNK als mögliche Verbindungsstelle der beiden Signalkaskaden, VEGF und MMR, identifiziert. Diese Hypothese wurde zusätzlich unterstützt durch die Tatsache, dass die JUN Expression unter diesen experimentellen Bedingungen reduziert war. Die Aufklärung der komplexen molekularen Mechanismen der potentiellen Interaktion bleibt zukünftigen Untersuchungen vorbehalten. In Hinblick auf die klinische Konsequenz der erhaltenen Ergebnisse war es auffällig, dass einige Zytokine durch Bevacizumab in den MMR defizienten Zellen im Gegensatz zu den MMR kompetenten Zellen unterschiedlich reguliert wurden. Die in-vitro verwendeten Behandlungsschemata waren den klinisch zur Anwendung kommenden Protokollen nachempfunden. Zuerst wurde ein DNA-Schaden gesetzt, und den Zellen ermöglicht, sich mit oder ohne Bevacizumab zu erholen. Es konnte gezeigt werden, dass die inflammatorischen Zytokine CCL7 und CCL8 eine höhere Expression in der MMR-defiziente Zelllinie in Kombination mit Bevacizumab aufweisen. Daher wurde ein möglicher Crosstalk zwischen von Tumorzellen sezernierten Faktoren und myeloischen Zellen weiter verfolgt. Veränderungen der Genexpression in Monozyten durch Tumorzell- konditionierte Medien zeigte CCL18 als ein Bevacizumab reguliertes Gen in MMR-defizienten Zellen, aber nicht in MMR kompetenten Zellen. CCL18 übt seine Funktion primär im adaptiven Immunsystems aus um eine TH2-Antwort in T-Zellen auszulösen Ausserdem wird eine Erhöhung der nicht-spezifische Phagozytose als weitere Funktion beschrieben. CCL18 wurde bereits als prognostischer Marker in Magen-, Dickdarm- und Eierstockkrebsarten beschrieben; die klinische Bedeutung ist jedoch abhängig von Tumortyp. Die Ergebnisse dieser Arbeit zeigen, dass eine Erhöhung der phagozytischen Aktivität von Makrophagen in Gegenwart von Bevacizumab wesentlich deutlicher in MMR-defizienten Zellen ausgeprägt war. Weiterhin wurde gefunden, dass nach DNA-Schädigung in Bevacizumab behandelten MMR-defizienten Zellen Zytokine freigesetzt werden, welche eine Monozytenmigration in einer Bevacizumab-abhängigen Weise induzieren. Dies weist auf eine funktionelle Interaktion von MMR-Defizienz und Bevacizumab hin. Zusätzlich zeigen die Ergebnisse dieser Arbeit eine Immunzellmodulation, die spezifisch für Mismatch-Reparatur defiziente Tumorzellen ist und in der klinischen Praxis als Marker für die Verabreichung von Bevacizumab verwendet werden könnte. KW - Angiogenesis KW - Immune KW - DNA Mismatch repair KW - Vascular endothelial Growth Factor KW - Inhibition KW - Angiogenese KW - Mismatch KW - DNS-Reparatur KW - Phagozytose Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-108302 ER - TY - THES A1 - Kuhtz, Juliane T1 - Epimutationen humaner Keimzellen und Infertilität T1 - Epimutations of human germ cells and infertility N2 - Infertilität stellt in unserer heutigen Gesellschaft ein zunehmendes Problem dar. Bei der Suche nach den der Infertilität zugrunde liegenden Ursachen gerät immer mehr die Epigenetik in den Fokus. Epigenetische Prozesse sind nicht nur in die Embryo-nalentwicklung und Wachstumsprozesse des Kindes involviert, sondern auch in korrekte Funktionsweisen von Gameten. Störungen können die Fertilität beeinträch-tigen. Eine besondere Rolle spielen geprägte Gene, die auf einem ihrer Allele, je nach parentaler Herkunft, ein Imprint in Form von DNA-Methylierung tragen. Fehl-regulationen solcher geprägter Gene können zu Imprinting-Erkrankungen führen. Seit Einführung der In-vitro-Fertilisation (IVF) wurden verschiedene assistierte Re-produktionstechniken (ART) entwickelt, um infertilen Paaren zu helfen. Die Sicher-heit dieser Techniken ist nicht abschließend geklärt. Immer wieder wird von nach ART-Behandlung gehäuft auftretenden Imprinting-Erkrankungen berichtet. Diese Erkrankungen stehen jedoch eher in Zusammenhang mit der zugrunde liegenden Infertilität, als mit ART selbst. Dennoch ist es notwendig zu untersuchen inwieweit sich ART eventuell auf den Gesundheitszustand dieser Kinder auswirken könnte. In der hier vorgelegten Arbeit wurde der Zusammenhang von Epigenetik, Infertilität und ART von verschiedenen Standpunkten aus beleuchtet. In humanen Spermien wurde die DNA-Methylierung verschiedener geprägter Gene hinsichtlich Epimutationen untersucht. ICSI (intracytoplasmatic sperm injection) und IMSI (intracytoplasmic morphologically selected sperm injection) sind verschiedene Techniken zur Selektion von Spermien für eine ART-Behandlung. Hier wurde un-tersucht, ob IMSI epigenetisch bessere Spermien selektiert als die konventionelle ICSI-Methode. Außerdem ist bekannt, dass in Spermienköpfen fertiler und infertiler Männer Vakuolen vorkommen können, deren epigenetische Bedeutung jedoch un-bekannt ist. Ob diese Vakuolen in Zusammenhang mit Epimutationen stehen könn-ten, wurde ebenfalls überprüft. Dazu wurde bisulfitkonvertierte DNA weniger Sper-mien (11 je Probe) mithilfe der Limiting Dilution (LD)–Technik und Pyrosequenzie-rung analysiert. Insgesamt standen 880 Spermien für diese Untersuchung zur Ver-fügung. Es konnte kein Unterschied zwischen IMSI- und ICSI-selektierten Spermien gefunden werden. Vorhandene Vakuolen im Spermienkopf beeinträchtigten nicht die DNA-Methylierung der Gene hGTL2, hLIT1 und hPEG3. Ein weiteres Projekt befasste sich mit der Frage, inwieweit die Technik der In-vitro-Maturation (IVM) DNA-Methylierung in humanen Oocyten beeinflussen könnte. Bisulfitkonvertierte DNA einzelner humaner Oocyten wurde mit LD und Pyrose-quenzierung analysiert. Verglichen wurden IVM und in vivo gereifte Oocyten. Hier-für standen 139 Oocyten zur Verfügung, wovon 90 mittels IVM und 49 in vivo gereift waren. Untersucht wurden vier geprägte Gene (hGTL2, hLIT1, hPEG3 und hSNRPN) und drei nicht geprägte Gene (hDNMT3Lo, hNANOG und hOCT4). Es konnten keine IVM-bedingten Epimutationen gefunden werden. Im dritten Projekt wurde untersucht, ob sich die DNA-Methylierung normaler Sper-mien von Spermien aus Oligozoospermie-Asthenozoospermie-Teratozoospermie (OAT)–Syndrom-Patienten unterscheidet. Eine weitere Frage war, ob Epimutationen einen Einfluss auf den ART-Ausgang haben. Untersucht wurden 54 Spermienpro-ben von Paaren in ART-Behandlung. Zur Untersuchung der DNA-Methylierungsmuster der geprägten Gene hGTL2 und hPEG3 sowie der beiden nicht geprägten Pluripotenzgene hNANOG und hOCT4 wurde die Methode Deep Bisulfite Sequencing (DBS) verwendet. Dies ist eine Next Generation Sequencing (NGS)–Technik, angewandt an bisulfitkonvertierter DNA. Diese Technik ermöglicht es mehrere Proben sowie Gene gleichzeitig zu analysieren. Es zeigte sich, dass OAT-Spermien, die zu einer Lebendgeburt geführt hatten, sich epigenetisch nicht von normalen Spermien unterschieden. Besonders viele Epimutationen konnten hingegen in OAT-Spermien gefunden werden, die zu keiner Schwangerschaft ge-führt hatten. Zwischen Spermien die zu einer Lebendgeburt oder keiner Schwan-gerschaft geführt hatten, zeigten sich Unterschiede in der Häufigkeit von hGTL2-Epimutationen. Über die Häufigkeit von Epimutationen konnte eine prädiktive Aus-sage zum ART-Ausgang getroffen werden. Zusammenfassend konnte in dieser Arbeit festgestellt werden, dass sich eine Häu-fung von Epimutationen darauf auswirkt, ob eine Schwangerschaft erreicht werden kann oder nicht. Diese Epimutationen liegen bereits im parentalen Genom vor. Sie werden nicht durch ART verursacht. Allerdings muss man Techniken finden, mit denen man Gameten mit möglichst wenig Epimutationen selektiert, um eine Über-tragung solcher auf das Kind zu verhindern. N2 - Infertility is an increasing problem in today’s society. The search for the underlying causes of infertility reveals more and more the role of epigenetics. Epigenetic pro-cesses are involved in embryo development and growth, but also in the proper func-tion of gametes. Disturbances have been shown to impair fertility. Imprinted genes play an important role. They carry a parental-specific DNA methylation imprint on one of their alleles. Deregulation of these genes leads to imprinting diseases. Since the introduction of in vitro fertilisation (IVF), different assisted reproductive technologies (ART) have been developed to treat infertile couples. The safety of these techniques is not finally solved. Increased rates of imprinting diseases in ART offspring have been reported, but seem more likely to be linked to the underlying parental infertility problems than to ART itself. Nevertheless it is of importance to in-vestigate how ART could affect the health of those children. In the work presented here the relations between epigenetics, infertility and ART have been investigated from different points of view. Firstly, the DNA methylation pattern of different imprinted genes has been investi-gated in human sperm with regard to the frequency of epimutations. ICSI (intracyto-plasmatic sperm injection) and IMSI (intracytoplasmic morphologically selected sperm injection) are different techniques to select sperm for ART treatment. It was analysed whether IMSI selects epigenetically superior sperm than the conventional ICSI method. Furthermore it is known that sperm from fertile and infertile men can carry vacuoles in their sperm heads. Their epigenetic relevance is unknown. Whether these vacuoles are linked to epimutations has also been investigated here. Bisulfite converted DNA of a few sperm (11 per sample) was analysed using the Limiting Dilution (LD) technique followed by pyrosequencing. In total 880 sperm were available for analysis. No difference between IMSI and ICSI selected sperm was found. Further, no influence of sperm head vacuoles on the DNA methylation patterns of the genes hGTL2, hLIT1 and hPEG3 could be observed. Secondly, it was of interest whether the in vitro maturation (IVM) technique has an influence on DNA methylation in human oocytes. Bisulfite converted DNA of single human oocytes was analysed with LD and pyrosequencing. IVM oocytes were com-pared to in vivo grown oocytes. A total of 139 oocytes were available, of which 90 oocytes were IVM treated while 49 oocytes were grown in vivo. Four imprinted genes (hGTL2, hLIT1, hPEG3 and hSNRPN) and three non-imprinted genes (hDNMT3Lo, hNANOG and hOCT4) were analysed. No IVM-induced epimutations were detected. Finally, it was investigated whether DNA methylation patterns of normal sperm would differ from sperm of oligozoospermia-asthenozoospermia-teratozoospermia (OAT) syndrome patients. Furthermore it was of interest whether epimutations would influence the ART outcome. A total of 54 sperm samples from couples undergoing ART treatment were investigated. To analyse DNA methylation of the imprinted genes hGTL2 and hPEG3 as well as the non-imprinted pluripotency genes hNANOG and hOCT4, Deep Bisulfite Sequencing (DBS) was applied. This is a Next Generation Sequencing (NGS) technique applied on bisulfite converted DNA, al-lowing the analysis of several samples and genes at once. The obtained results showed that OAT samples, which had led to a live-birth, did not differ epigenetically from normal sperm. Much more epimutations were found in OAT sperm which had failed to achieve a pregnancy. Sperm not being able to achieve a pregnancy differed from sperm that had led to a live-birth with regard to hGTL2 epimutation frequency. In addition, ART outcome can be predicted using the frequency of epimutations. Taken together this work shows that the amount of epimutations influences whether a pregnancy can be achieved or not. Epimutations already exist within the parental genome. They are not caused by ART. Nevertheless, one needs to find techniques with which gametes with as few as possible epimutations are being selected to pre-vent the transmission of these onto the offspring. KW - Epigenetik KW - Sterilität KW - Epimutationen KW - geprägte Gene KW - humane Keimzellen KW - Infertilität Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-108248 ER - TY - THES A1 - Stangler, Eva T1 - Effects of habitat fragmentation on trap-nesting bees, wasps and their natural enemies in small secondary rainforest fragments in Costa Rica T1 - Die Auswirkungen von Habitatfragmentierung auf nisthilfenbewohnende Bienen, Wespen und deren Gegenspieler in kleinen Sekundärwaldfragmenten in Costa Rica N2 - Summary (English) I. Human induced global change threatens biodiversity and trophic interactions. Fragmentation is considered as one of the major threats to biodiversity and can cause reduced species richness, population declines, loss of genetic diversity and disruption of trophic interactions such as predation and parasitism. However forest fragmentation effects can be eclectic due to species specific traits. Specialist species with narrower niches or at higher trophic levels may be in danger of extinction whereas generalist species with less specific habitat requirements may even profit from fragmentation. In the tropics, known as “the” terrestrial biodiversity hotspots, even biodiversity inventories are often lacking, especially in forest canopies. Ongoing deforestation and resulting fragmentation in tropical regions are expected to heavily affect ecosystem functions by changes in biodiversity, community compositions and disruption of trophic interactions. It is even less unknown in what extent different global change drivers for example climate change and fragmentation interact. It is unlikely that deforestation will end, so that small secondary forest fragments will be important habitat elements that must be investigated to optimize their potential contribution to biodiversity conservation. This dissertation aimed to disentangle the effects of forest fragmentation on trap-nesting bee and wasp communities in small secondary forest fragments addressing the following main questions: 1) Are there interactive effects between microclimate and fragmentation on the abundance of bees and wasps, their mortality - and parasitism rates (Chapter II)? 2) How does fragmentation affect bee biodiversity from canopy to the understory with considerations of single species patterns (Chapter III)? 3) How is fragmentation affecting diversity and community composition of different trophic levels between understory and canopy with emphasis on the host-antagonist relation? (Chapter IV). II. A variety of global change drivers affect biodiversity and trophic interactions. The combined effects of habitat fragmentation and climate change are poorly understood and with ongoing deforestation and agricultural intensification secondary rainforest fragments might contribute to biodiversity conservation and mitigation of climate warming. This chapter investigated the interactive effects of habitat fragmentation and microclimate on the abundance and biotic interactions of trap-nesting bees and wasps in secondary forest fragments in the Northeastern lowlands of Costa Rica. Habitat area did not affect hymenopteran abundance, parasitism and mortality rates, but tree location- from the forest border to the forest center- influenced all variables. Interactive effects were found such as in the higher mortality rates at interior locations in larger fragments. Mean temperature at edge and interior locations led to significant effects on all tested variables and interactive effects between temperature and tree locations were found. Abundances at interior locations were significantly higher with increasing temperatures. Mortality rates at interior location increased at lower mean temperatures, whereas higher temperatures at edges marginally increased mortality rates. Our results indicate, that edge effects, mediated by altered microclimatic conditions, significantly change biotic interactions of trap-nesting hymenopterans in small secondary fragments. III. This chapter focusses on the vertical distribution of bees, their parasitism and mortality rates as well as single species patterns in relation to fragment size and edge effects in secondary rainforest remnants. No size effects on bee abundance, bee diversity and on parasitism- and mortality rates were found. Bees were least abundant at the intermediate height and were most abundant in the understory; whereas the highest diversity was found in the canopy. Tree location had no effect on bee abundance, but on bee diversity since most species were found in the forest interior. The cuckoo bees Aglaomelissa duckei and Coelioxys sp. 1 only partly followed the patterns of their hosts, two Centris species. Edge effects greatly influenced the bee community, so that the amount of edge habitat in secondary forest fragments will influence the conservation value for bees. IV. In this section the effects of habitat fragmentation on biodiversity, on community structure of hosts and natural enemies as well as the relation of hosts and antagonists were investigated from the understory to the canopy. The results stress the importance to monitor biodiversity, community composition and trophic interactions from the understory to the canopy. The higher trophic level of the antagonists was found to be more sensitive to fragment size compared to their hosts. Again edge effects were found to be the dominant driver since both host and antagonist richness, as well as community compositions were strongly affected. Ongoing fragmentation and increased amount of edge habitat could favor few abundant disturbance-adapted species over the rare and more diverse forest-adapted species. A positive-density dependent parasitism rate was demonstrated, as well as an increase of the parasitism rate not only with antagonist abundance but also diversity. Small secondary forest fragments surely can contribute to the conservation of biodiversity and trophic interactions, but increase of edge habitat will have negative consequences on above-ground nesting Hymenoptera, so that important interactions such as pollination, predation and parasitism could be disrupted. Therefore small forest fragments could contribute to biodiversity conservation but will not be able to compensate for the loss of large areas of primary forests. V. This dissertation contributes to the understanding of habitat area - and edge effects as well as the interaction of those with microclimatic conditions in small secondary rainforest fragments. As study system trap nests inhabited by solitary above-ground nesting bees, wasps and their natural enemies were chosen because they allow to study trophic interactions along their whole vertical distribution from the understory to the canopy. The effect of fragment size was rather weak, however, larger sizes affected the diversity of natural enemies positively, proofing the hypothesis that higher trophic levels react more sensitive to habitat loss. Edge effects heavily affected the abundance, diversity and community composition of hosts and their natural enemies as well as parasitism and mortality rates. Increased edge conditions resulting from ongoing fragmentation and deforestation will therefore negatively affect bees, wasps and their trophic interactions with natural enemies. Those changes affect important processes such as pollination, predation and parasitism, which could result in changes of ecosystem functioning. This study showed the importance to include all strata in biodiversity monitoring since height did matter for the trap-nesting communities. Diversity was shown to be higher in the canopy and community composition did change significantly. To conclude we could show that secondary forest fragments can sustain a trap-nesting bee and wasp community, but the amount of interior habitat is highly important for the conservation of forest-adapted species. Probably the conservation of large primary forest in combination with a high habitat connectivity, for example with small secondary forest fragments, will help to sustain biodiversity and ecosystem functioning better than the mere presence of small forest fragments. N2 - Zusammenfassung (German) I. Die weltweite Umweltveränderung, die durch den Menschen verursacht wird, gefährdet die Artenvielfalt und die trophischen Wechselbeziehungen zwischen Organismen. Fragmentierung gilt als eine der Hauptbedrohungen für die Biodiversität und kann weitreichende Konsequenzen haben wie zum Beispiel verminderte Artenvielfalt, Rückgang von Populationen, Verlust von genetischer Diversität und auch die Unterbrechung von trophischen Interaktionen, z.B. Prädation und Parasitierung. In Waldökosystemen können Fragmentierungsauswirkungen vielfältig sein. Spezialisierte Arten mit engen natürlichen Nischen, die zum Beispiel in höheren trophischen Ebenen zu finden sind, könnten vom Aussterben bedroht sein, während generalisierte Arten mit weniger spezifischen Habitatansprüchen sogar profitieren könnten. In den Tropen, „den“ terrestrischen Biodiversitäts-Hotspots, fehlen oft sogar grundlegende Bestandsaufnahmen von Flora und Fauna, insbesondere für die Kronen der Regenwälder. Die fortschreitende Abholzung in tropischen Regionen und die dadurch verursachte Fragmentierung wird die Funktion des Ökosystems durch Veränderung der Artenvielfalt, der Zusammensetzung von Artengemeinschaften und der Unterbrechung von trophischen Interaktionen in hohem Maße beeinflussen. Besonders das Zusammenwirken von verschiedenen Facetten des globalen Umweltwandels, z. B. Klimawandel und Fragmentierung, ist nahezu unbekannt. Da es unwahrscheinlich ist, dass die Abholzung von Regenwäldern eingestellt wird, ist es äußerst wichtig den Wert von kleinen Sekundärwaldfragmenten für den Schutz der Artenvielfalt zu untersuchen. Diese Dissertation trägt dazu bei verschiedene Aspekte der Fragmentierung auf die Artengemeinschaft von nisthilfenbewohnenden Hymenopteren in kleinen Sekundärwaldfragmenten zu untersuchen und behandelt dabei die folgenden zentralen Fragen: 1) Wirken Fragmentierung und mikroklimatische Bedingungen interaktiv auf die Abundanz von Bienen und Wespen sowie deren Mortalitäts- und Parasitierungsraten (2. Kapitel)? 2) Wie beeinflusst Fragmentierung die Artenvielfalt von Bienen vom Unterholz bis zur Krone und wie reagieren einzelne Arten darauf (3. Kapitel)? 3) Wie beeinflusst Fragmentierung die Biodiversität und die Artengemeinschaften verschiedener trophischer Ebenen vom Unterholz bis zum Kronendach unter besonderer Berücksichtigung der Wirts-Antagonist-Beziehung (4. Kapitel)? II. Eine Reihe von Faktoren des weltweiten Umweltwandels beeinflusst die Artenvielfalt und trophische Interaktionen. Die Auswirkungen von Fragmentierung und Klimawandel, die sich gegenseitig beeinflussen könnten, sind nahezu unverstanden. Außerdem könnten Sekundärwaldfragmente zum Erhalt der Artenvielfalt und der Abschwächung der Auswirkungen des Klimawandels sowie der anhaltenden Abholzung und der Intensivierung der Landwirtschaft dienen. Dieser Abschnitt untersucht mögliche Wechselwirkungen zwischen Fragmentierung und Temperatur auf die Abundanz und trophische Interaktionen von nisthilfenbewohnenden Bienen und Wespen in kleinen Sekundärwaldfragmenten im Nordosten Costa Ricas. Die Fragmentgröße hatte keinen Einfluss auf die Abundanz, die Parasitierungs- und Mortalitätsraten der Hymenopteren, während der Baumstandort- vom Waldrand zur Waldmitte immensen Einfluss auf alle untersuchten Variablen hatte. In größeren Fragmenten war die Mortalitätsrate innerhalb des Waldes verglichen mit kleineren Fragmenten höher. Die mittlere Temperatur beeinflusste alle untersuchten Variablen und hatte je nach Standort des Baumes unterschiedliche Auswirkungen. Die Abundanzen im Waldinneren stiegen signifikant mit höheren Temperaturen an. Die Mortalitätsraten im Waldinneren nahmen mit niedrigeren Temperaturen zu, während höhere Temperaturen am Waldrand zu höheren Mortalitätsraten führten. Unsere Ergebnisse zeigen, dass Randeffekte, die auch durch Temperaturunterschiede zustande kommen, biotische Interaktionen von nisthilfenbewohnenden Bienen und Wespen in kleinen Sekundärwaldfragmenten ändern. III. Dieses Kapitel konzentriert sich auf den Einfluss der Fragmentgröße und der Randeffekte auf Bienen und deren Parasitierungs- und Mortalitätsraten vom Unterholz bis zu den Kronendächern in kleinen Sekundärwaldfragmenten. Dabei wurden auch die Muster von einzelnen Arten näher untersucht. Die Fragmentgröße hatte keinen Einfluss auf die Bienenabundanz, die Artenvielfalt oder die Parasitierungs- und Mortalitätsraten. Die höchste Bienenabundanz wies das Unterholz auf, während die höchste Diversität im Kronendach gefunden wurde. Der Gradient vom Waldrand bis zur Waldmitte hatte keinen Einfluss auf die Bienenabundanz, wohingegen die Diversität zum Waldinnern hin anstieg. Die Kuckucksbienen Aglaomelissa duckei und Coelioxys sp. 1 folgten nur zum Teil den Mustern ihrer Wirte, zwei Centris Arten. Randeffekte hatten großen Einfluss auf die Bienengemeinschaften, so dass der Anteil von Waldrändern bzw. die Form der Sekundärwaldfragmente über den Nutzen für die Erhaltung der Bienenvielfalt bestimmt. IV. In diesem Kapitel wurden die Fragmentierungsauswirkungen auf die Biodiversität, die Gemeinschaftszusammensetzung von Wirten und ihrer natürlichen Feinde als auch die Beziehung zwischen den Wirten und ihren natürlichen Feinden vom Unterholz bis zum Kronendach untersucht. Die Ergebnisse zeigten, dass es äußerst wichtig ist die Biodiversität, die Zusammensetzung der Artengemeinschaft als auch die trophischen Interaktionen in den verschiedenen Straten des Regenwaldes zu untersuchen. Die natürlichen Feinde, die auf einer höheren trophischen Ebene stehen, reagierten empfindlicher auf die Größe der Fragmente. Randeffekte waren der einflussreichste Faktor, weil die Diversität der Wirte und der natürlichen Feinde, sowie deren Artengemeinschaften stark beeinflusst wurden. Fortschreitende Fragmentierung und der damit einhergehende erhöhte Flächenanteil des Randhabitats könnte daher wenige häufige Arten bevorzugen, die gestörtes Habitat tolerieren können, wohingegen die seltenere aber artenreichere Gemeinschaft, die das Waldinnere bevorzugt, benachteiligt wird. Es konnte außerdem eine positiv-dichteabhängige Parasitierungsrate sowie ein positiver Zusammenhang zwischen der Abundanz und Diversität von natürlichen Feinden und der Parasitierungsrate gezeigt werden. Kleine Sekundärwaldfragmente können sicherlich helfen die Artenvielfalt und die trophischen Interaktionen zu erhalten, aber die Erhöhung des Anteils von Randhabitat wird nachteilige Folgen für solitäre Hymenopteren haben. Dies kann zur Unterbrechung von wichtigen Interaktionen wie Bestäubung, Prädation und Parasitierung führen. Kleine Sekundärwaldfragmente können daher zwar hilfreich zur Erhaltung der Biodiversität sein, aber niemals große Primärwaldflächen, die von unschätzbarem Wert sind, ersetzen. V. Die vorliegende Doktorarbeit trägt zum Verständnis der Auswirkungen der Habitatgröße und von Randeffekten als auch deren Wechselwirkungen mit mikroklimatischen Bedingungen in kleinen Sekundärwaldfragmenten bei. Benutzt wurden Nisthilfen, die von solitären Bienen, Wespen und ihren natürlichen Feinden besiedelt werden, da hierdurch auch trophische Interaktionen vom Unterholz bis zum Kronendach aufgenommen werden können. Die Fragmentgröße hatte keine weitreichenden Auswirkungen. Größere Fragmente wiesen allerdings eine höhere Vielfalt von natürlichen Feinden auf, was die Hypothese der höheren Empfindlichkeit von höheren trophischen Ebenen bestätigt. Randeffekte hingegen haben sowohl die Bienen und Wespen als Wirte als auch deren natürliche Feinde in ihrer Häufigkeit, Artenvielfalt und Artenzusammensetzung in hohem Maße beeinflusst. Eine Erhöhung des Anteils von Randhabitaten, die mit fortschreitender Abholzung und Fragmentierung einhergeht, wird daher einen negativen Einfluss auf diese Hymenopteren haben, was sogar die Funktion des Ökosystems beeinflussen könnte, da dadurch auch wichtige Interaktionen, zum Beispiel Bestäubung, Prädation und Parasitierung beeinträchtigt werden. Außerdem konnte diese Doktorarbeit zeigen, dass es unbedingt notwendig ist die Fauna des gesamten Regenwaldes unter Berücksichtigung aller Straten aufzunehmen. Die Artenvielfalt in der Kronenschicht war höher und auch die Zusammensetzung der Artengemeinschaften war signifikant verschieden zwischen dem Unterholz und den Kronendächern. Diese Doktorarbeit zeigt, dass kleine Sekundärwaldfragmente zwar Lebensraum und Ressourcen für eine Gemeinschaft von solitären Bienen, Wespen und deren natürlichen Gegenspielern bieten kann, dass jedoch die Form und damit der Anteil von Innenhabitat ausschlaggebend für den Erhalt von spezialisierten Waldarten ist. Der Erhalt von großen Flächen von Primärwald ist daher unabdingbar, jedoch könnten Sekundärwaldfragmente zur Erhöhung der Vernetzung beitragen, um so ein stabiles, artenreiches und einzigartiges Waldökosystem zu erhalten, was allein durch kleine Sekundärwaldfragmente nicht möglich sein wird. KW - Costa Rica KW - Sekundärwald KW - natural enemies KW - secondary rainforest fragments KW - Hymenoptera KW - Bienen KW - Wespen KW - Nisthilfe KW - Fragmentierung Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-108254 ER - TY - JOUR A1 - Floren, Andreas A1 - Krüger, Dirk A1 - Müller, Tobias A1 - Dittrich, Marcus A1 - Rudloff, Renate A1 - Hoppe, Björn A1 - Linsenmair, Karl Eduard T1 - Diversity and interactions of wood-inhabiting fungi and beetles after deadwood enrichment JF - PLoS ONE N2 - Freshly cut beech deadwood was enriched in the canopy and on the ground in three cultural landscapes in Germany (Swabian Alb, Hainich-Dun, Schorfheide-Chorin) in order to analyse the diversity, distribution and interaction of wood-inhabiting fungi and beetles. After two years of wood decay 83 MOTUs (Molecular Operational Taxonomic Units) from 28 wood samples were identified. Flight Interception Traps (FITs) installed adjacent to the deadwood enrichments captured 29.465 beetles which were sorted to 566 species. Geographical 'region' was the main factor determining both beetle and fungal assemblages. The proportions of species occurring in all regions were low. Statistic models suggest that assemblages of both taxa differed between stratum and management praxis but their strength varied among regions. Fungal assemblages in Hainich-Dun, for which the data was most comprehensive, discriminated unmanaged from extensively managed and age-class forests (even-aged timber management) while canopy communities differed not from those near the ground. In contrast, the beetle assemblages at the same sites showed the opposite pattern. We pursued an approach in the search for fungus-beetle associations by computing cross correlations and visualize significant links in a network graph. These correlations can be used to formulate hypotheses on mutualistic relationships for example in respect to beetles acting as vectors of fungal spores. KW - european beech forests KW - bark beetles KW - management KW - decay KW - ecology KW - norway spruce KW - substrate quality KW - communities KW - rare Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-145129 VL - 10 IS - 11 ER - TY - JOUR A1 - Laine, Romain F. A1 - Albecka, Anna A1 - van de Linde, Sebastian A1 - Rees, Eric J. A1 - Crump, Colin M. A1 - Kaminski, Clemens F. T1 - Structural analysis of herpes simplex virus by optical super-resolution imaging JF - Nature Communications N2 - Herpes simplex virus type-1 (HSV-1) is one of the most widespread pathogens among humans. Although the structure of HSV-1 has been extensively investigated, the precise organization of tegument and envelope proteins remains elusive. Here we use super-resolution imaging by direct stochastic optical reconstruction microscopy (dSTORM) in combination with a model-based analysis of single-molecule localization data, to determine the position of protein layers within virus particles. We resolve different protein layers within individual HSV-1 particles using multi-colour dSTORM imaging and discriminate envelope-anchored glycoproteins from tegument proteins, both in purified virions and in virions present in infected cells. Precise characterization of HSV-1 structure was achieved by particle averaging of purified viruses and model-based analysis of the radial distribution of the tegument proteins VP16, VP1/2 and pUL37, and envelope protein gD. From this data, we propose a model of the protein organization inside the tegument. KW - tegument protein pUL36 KW - fluorescence microscopy KW - monoclonal antibodies KW - 3-dimensional structure KW - type-1 KW - nuclear pore complex KW - reconstruction microscopy KW - localization microscopy KW - resolution KW - envelopment Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-144623 VL - 6 IS - 5980 ER - TY - JOUR A1 - Scholz, Nicole A1 - Gehring, Jennifer A1 - Guan, Chonglin A1 - Ljaschenko, Dmitrij A1 - Fischer, Robin A1 - Lakshmanan, Vetrivel A1 - Kittel, Robert J. A1 - Langenhan, Tobias T1 - The adhesion GPCR Latrophilin/CIRL shapes mechanosensation JF - Cell Reports N2 - G-protein-coupled receptors (GPCRs) are typically regarded as chemosensors that control cellular states in response to soluble extracellular cues. However, the modality of stimuli recognized through adhesion GPCR (aGPCR), the second largest class of the GPCR superfamily, is unresolved. Our study characterizes the Drosophila aGPCR Latrophilin/dCirl, a prototype member of this enigmatic receptor class. We show that dCirl shapes the perception of tactile, proprioceptive, and auditory stimuli through chordotonal neurons, the principal mechanosensors of Drosophila. dCirl sensitizes these neurons for the detection of mechanical stimulation by amplifying their input-output function. Our results indicate that aGPCR may generally process and modulate the perception of mechanical signals, linking these important stimuli to the sensory canon of the GPCR superfamily. KW - \(\alpha\)-latrotoxin KW - chordotonal organs KW - Johnstons organ KW - ligand CD55 KW - hearing KW - binding KW - shear stress KW - protein-coupled receptors KW - drosophila larvae KW - domain Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-148626 VL - 11 ER - TY - JOUR A1 - Gao, Shiqiang A1 - Nagpal, Jatin A1 - Schneider, Martin W. A1 - Kozjak-Pavlovic, Vera A1 - Nagel, Georg A1 - Gottschalk, Alexander T1 - Optogenetic manipulation of cGMP in cells and animals by the tightly light-regulated guanylyl-cyclase opsin CyclOp JF - Nature Communications N2 - Cyclic GMP (cGMP) signalling regulates multiple biological functions through activation of protein kinase G and cyclic nucleotide-gated (CNG) channels. In sensory neurons, cGMP permits signal modulation, amplification and encoding, before depolarization. Here we implement a guanylyl cyclase rhodopsin from Blastocladiella emersonii as a new optogenetic tool (BeCyclOp), enabling rapid light-triggered cGMP increase in heterologous cells (Xenopus oocytes, HEK293T cells) and in Caenorhabditis elegans. Among five different fungal CyclOps, exhibiting unusual eight transmembrane topologies and cytosolic N-termini, BeCyclOp is the superior optogenetic tool (light/dark activity ratio: 5,000; no cAMP production; turnover (20 °C) ~17 cGMPs\(^{-1}\)). Via co-expressed CNG channels (OLF in oocytes, TAX-2/4 in C. elegans muscle), BeCyclOp photoactivation induces a rapid conductance increase and depolarization at very low light intensities. In O\(_2\)/CO\(_2\) sensory neurons of C. elegans, BeCyclOp activation evokes behavioural responses consistent with their normal sensory function. BeCyclOp therefore enables precise and rapid optogenetic manipulation of cGMP levels in cells and animals. KW - carbon dioxide avoidance KW - III adenylyl cyclases KW - rhodopsin KW - in vivo KW - optical control KW - Halobacterium halobium KW - C. elegans KW - cellular camp KW - Caenorhabditis elegans KW - nucleotide-gated channel Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-148197 VL - 6 IS - 8046 ER - TY - JOUR A1 - Wäldchen, Sina A1 - Lehmann, Julian A1 - Klein, Teresa A1 - van de Linde, Sebastian A1 - Sauer, Markus T1 - Light-induced cell damage in live-cell super-resolution microscopy JF - Scientific Reports N2 - Super-resolution microscopy can unravel previously hidden details of cellular structures but requires high irradiation intensities to use the limited photon budget efficiently. Such high photon densities are likely to induce cellular damage in live-cell experiments. We applied single-molecule localization microscopy conditions and tested the influence of irradiation intensity, illumination-mode, wavelength, light-dose, temperature and fluorescence labeling on the survival probability of different cell lines 20-24 hours after irradiation. In addition, we measured the microtubule growth speed after irradiation. The photo-sensitivity is dramatically increased at lower irradiation wavelength. We observed fixation, plasma membrane permeabilization and cytoskeleton destruction upon irradiation with shorter wavelengths. While cells stand light intensities of similar to 1 kW cm\(^{-2}\) at 640 nm for several minutes, the maximum dose at 405 nm is only similar to 50 J cm\(^{-2}\), emphasizing red fluorophores for live-cell localization microscopy. We also present strategies to minimize phototoxic factors and maximize the cells ability to cope with higher irradiation intensities. KW - optical reconstruction microscopy KW - tag fusion proteins KW - localization microscopy KW - photodynamic therapy KW - diffraction limit KW - illumination microscopy KW - structured illumination KW - fluorescent probes KW - in vitro KW - dynamics Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-145207 VL - 5 IS - 15348 ER - TY - JOUR A1 - Remmele, Christian W. A1 - Luther, Christian H. A1 - Balkenhol, Johannes A1 - Dandekar, Thomas A1 - Müller, Tobias A1 - Dittrich, Marcus T. T1 - Integrated inference and evaluation of host-fungi interaction networks JF - Frontiers in Microbiology N2 - Fungal microorganisms frequently lead to life-threatening infections. Within this group of pathogens, the commensal Candida albicans and the filamentous fungus Aspergillus fumigatus are by far the most important causes of invasive mycoses in Europe. A key capability for host invasion and immune response evasion are specific molecular interactions between the fungal pathogen and its human host. Experimentally validated knowledge about these crucial interactions is rare in literature and even specialized host pathogen databases mainly focus on bacterial and viral interactions whereas information on fungi is still sparse. To establish large-scale host fungi interaction networks on a systems biology scale, we develop an extended inference approach based on protein orthology and data on gene functions. Using human and yeast intraspecies networks as template, we derive a large network of pathogen host interactions (PHI). Rigorous filtering and refinement steps based on cellular localization and pathogenicity information of predicted interactors yield a primary scaffold of fungi human and fungi mouse interaction networks. Specific enrichment of known pathogenicity-relevant genes indicates the biological relevance of the predicted PHI. A detailed inspection of functionally relevant subnetworks reveals novel host fungal interaction candidates such as the Candida virulence factor PLB1 and the anti-fungal host protein APP. Our results demonstrate the applicability of interolog-based prediction methods for host fungi interactions and underline the importance of filtering and refinement steps to attain biologically more relevant interactions. This integrated network framework can serve as a basis for future analyses of high-throughput host fungi transcriptome and proteome data. KW - candida genome database KW - computational prediction KW - potential role KW - network inference KW - bioinformatics and computational biology KW - protein interaction database KW - Aspergillus fumigatus KW - cell wall KW - functional modules KW - alzheimers disease KW - molecular cloning KW - Candida albicans KW - pathogen-host interaction (PHI) KW - protein-protein interaction KW - pathogenicity KW - interolog Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-148278 VL - 6 IS - 764 ER - TY - JOUR A1 - Karl, Stefan A1 - Dandekar, Thomas T1 - Convergence behaviour and control in non-linear biological networks JF - Scientific Reports N2 - Control of genetic regulatory networks is challenging to define and quantify. Previous control centrality metrics, which aim to capture the ability of individual nodes to control the system, have been found to suffer from plausibility and applicability problems. Here we present a new approach to control centrality based on network convergence behaviour, implemented as an extension of our genetic regulatory network simulation framework Jimena (http://stefan-karl.de/jimena). We distinguish three types of network control, and show how these mathematical concepts correspond to experimentally verified node functions and signalling pathways in immunity and cell differentiation: Total control centrality quantifies the impact of node mutations and identifies potential pharmacological targets such as genes involved in oncogenesis (e.g. zinc finger protein GLI2 or bone morphogenetic proteins in chondrocytes). Dynamic control centrality describes relaying functions as observed in signalling cascades (e.g. src kinase or Jak/Stat pathways). Value control centrality measures the direct influence of the value of the node on the network (e.g. Indian hedgehog as an essential regulator of proliferation in chondrocytes). Surveying random scale-free networks and biological networks, we find that control of the network resides in few high degree driver nodes and networks can be controlled best if they are sparsely connected. KW - complex networks KW - control profiles KW - differentiation KW - pathways KW - tumors KW - models KW - centrality KW - chondrosarcoma KW - transcriptional regulation KW - regulatory networks Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-148510 VL - 5 IS - 09746 ER - TY - JOUR A1 - Matos, I A1 - Machado, M. P. A1 - Schartl, M. A1 - Coelho, M. M. T1 - Gene expression dosage regulation in an allopolyploid fish JF - PLoS ONE N2 - How allopolyploids are able not only to cope but profit from their condition is a question that remains elusive, but is of great importance within the context of successful allopolyploid evolution. One outstanding example of successful allopolyploidy is the endemic Iberian cyprinid Squalius alburnoides. Previously, based on the evaluation of a few genes, it was reported that the transcription levels between diploid and triploid S. alburnoides were similar. If this phenomenon occurs on a full genomic scale, a wide functional "diploidization'' could be related to the success of these polyploids. We generated RNA-seq data from whole juvenile fish and from adult livers, to perform the first comparative quantitative transcriptomic analysis between diploid and triploid individuals of a vertebrate allopolyploid. Together with an assay to estimate relative expression per cell, it was possible to infer the relative sizes of transcriptomes. This showed that diploid and triploid S. alburnoides hybrids have similar liver transcriptome sizes. This in turn made it valid to directly compare the S. alburnoides RNA-seq transcript data sets and obtain a profile of dosage responses across the S. alburnoides transcriptome. We found that 64% of transcripts in juveniles' samples and 44% in liver samples differed less than twofold between diploid and triploid hybrids (similar expression). Yet, respectively 29% and 15% of transcripts presented accurate dosage compensation (PAA/PA expression ratio of 1 instead of 1.5). Therefore, an exact functional diploidization of the triploid genome does not occur, but a significant down regulation of gene expression in triploids was observed. However, for those genes with similar expression levels between diploids and triploids, expression is not globally strictly proportional to gene dosage nor is it set to a perfect diploid level. This quantitative expression flexibility may be a strong contributor to overcome the genomic shock, and be an immediate evolutionary advantage of allopolyploids. KW - RNA-Seq KW - balance hypothesis KW - hybrids KW - genome KW - maize KW - Squalius alburnoides KW - cell size KW - evolution KW - heterosis KW - complex Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-143565 VL - 10 IS - 3 ER - TY - JOUR A1 - Alizadehrad, Davod A1 - Krüger, Timothy A1 - Engstler, Markus A1 - Stark, Holger T1 - Simulating the complex cell design of Trypanosoma brucei and its motility JF - PLOS Computational Biology N2 - The flagellate Trypanosoma brucei, which causes the sleeping sickness when infecting a mammalian host, goes through an intricate life cycle. It has a rather complex propulsion mechanism and swims in diverse microenvironments. These continuously exert selective pressure, to which the trypanosome adjusts with its architecture and behavior. As a result, the trypanosome assumes a diversity of complex morphotypes during its life cycle. However, although cell biology has detailed form and function of most of them, experimental data on the dynamic behavior and development of most morphotypes is lacking. Here we show that simulation science can predict intermediate cell designs by conducting specific and controlled modifications of an accurate, nature-inspired cell model, which we developed using information from live cell analyses. The cell models account for several important characteristics of the real trypanosomal morphotypes, such as the geometry and elastic properties of the cell body, and their swimming mechanism using an eukaryotic flagellum. We introduce an elastic network model for the cell body, including bending rigidity and simulate swimming in a fluid environment, using the mesoscale simulation technique called multi-particle collision dynamics. The in silico trypanosome of the bloodstream form displays the characteristic in vivo rotational and translational motility pattern that is crucial for survival and virulence in the vertebrate host. Moreover, our model accurately simulates the trypanosome's tumbling and backward motion. We show that the distinctive course of the attached flagellum around the cell body is one important aspect to produce the observed swimming behavior in a viscous fluid, and also required to reach the maximal swimming velocity. Changing details of the flagellar attachment generates less efficient swimmers. We also simulate different morphotypes that occur during the parasite's development in the tsetse fly, and predict a flagellar course we have not been able to measure in experiments so far. KW - multiparticle collision dynamics KW - human african trypanosomiasis KW - biology KW - cytoskeleton KW - flow KW - flagellar motility KW - tsetse fly KW - propulsion KW - cytokinesis KW - parasites Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-144610 VL - 11 IS - 1 ER - TY - JOUR A1 - Schartl, Manfred A1 - Shen, Yingjia A1 - Maurus, Katja A1 - Walter, Ron A1 - Tomlinson, Chad A1 - Wilson, Richard K. A1 - Postlethwait, John A1 - Warren, Wesley C. T1 - Whole body melanoma transcriptome response in medaka JF - PLoS ONE N2 - The incidence of malignant melanoma continues to increase each year with poor prognosis for survival in many relapse cases. To reverse this trend, whole body response measures are needed to discover collaborative paths to primary and secondary malignancy. Several species of fish provide excellent melanoma models because fish and human melanocytes both appear in the epidermis, and fish and human pigment cell tumors share conserved gene expression signatures. For the first time, we have examined the whole body transcriptome response to invasive melanoma as a prelude to using transcriptome profiling to screen for drugs in a medaka (Oryzias latipes) model. We generated RNA-seq data from whole body RNA isolates for controls and melanoma fish. After testing for differential expression, 396 genes had significantly different expression (adjusted p-value <0.02) in the whole body transcriptome between melanoma and control fish; 379 of these genes were matched to human orthologs with 233 having annotated human gene symbols and 14 matched genes that contain putative deleterious variants in human melanoma at varying levels of recurrence. A detailed canonical pathway evaluation for significant enrichment showed the top scoring pathway to be antigen presentation but also included the expected melanocyte development and pigmentation signaling pathway. Results revealed a profound down-regulation of genes involved in the immune response, especially the innate immune system. We hypothesize that the developing melanoma actively suppresses the immune system responses of the body in reacting to the invasive malignancy, and that this mal-adaptive response contributes to disease progression, a result that suggests our whole-body transcriptomic approach merits further use. In these findings, we also observed novel genes not yet identified in human melanoma expression studies and uncovered known and new candidate drug targets for further testing in this malignant melanoma medaka model. KW - metastatic melanoma KW - expression KW - fish KW - cancer KW - stage III KW - melanogenesis KW - genome cells KW - gene KW - contributes Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-144714 VL - 10 IS - 12 ER - TY - JOUR A1 - Tuchscherr, Lorena A1 - Bischoff, Markus A1 - Lattar, Santiago M. A1 - Noto Llana, Mariangeles A1 - Pförtner, Henrike A1 - Niemann, Silke A1 - Geraci, Jennifer A1 - Van de Vyver, Hélène A1 - Fraunholz, Martin J. A1 - Cheung, Ambrose L. A1 - Herrmann, Mathias A1 - Völker, Uwe A1 - Sordelli, Daniel O. A1 - Peters, Georg A1 - Loeffler, Bettina T1 - Sigma factor SigB is crucial to mediate Staphylococcus aureus adaptation during chronic infections JF - PLoS Pathogens N2 - Staphylococcus aureus is a major human pathogen that causes a range of infections from acute invasive to chronic and difficult-to-treat. Infection strategies associated with persisting S. aureus infections are bacterial host cell invasion and the bacterial ability to dynamically change phenotypes from the aggressive wild-type to small colony variants (SCVs), which are adapted for intracellular long-term persistence. The underlying mechanisms of the bacterial switching and adaptation mechanisms appear to be very dynamic, but are largely unknown. Here, we analyzed the role and the crosstalk of the global S. aureus regulators agr, sarA and SigB by generating single, double and triple mutants, and testing them with proteome analysis and in different in vitro and in vivo infection models. We were able to demonstrate that SigB is the crucial factor for adaptation in chronic infections. During acute infection, the bacteria require the simultaneous action of the agr and sarA loci to defend against invading immune cells by causing inflammation and cytotoxicity and to escape from phagosomes in their host cells that enable them to settle an infection at high bacterial density. To persist intracellularly the bacteria subsequently need to silence agr and sarA. Indeed agr and sarA deletion mutants expressed a much lower number of virulence factors and could persist at high numbers intracellularly. SigB plays a crucial function to promote bacterial intracellular persistence. In fact, \(\Delta\)sigB-mutants did not generate SCVs and were completely cleared by the host cells within a few days. In this study we identified SigB as an essential factor that enables the bacteria to switch from the highly aggressive phenotype that settles an acute infection to a silent SCV-phenotype that allows for long-term intracellular persistence. Consequently, the SigB-operon represents a possible target to develop preventive and therapeutic strategies against chronic and therapy-refractory infections. KW - gene regulator agr KW - endothelial cells KW - modulates virulence KW - death pathway sar locus KW - factor B KW - small-colony variants KW - alpha-toxin KW - epithelial cells KW - in vitro Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-143419 VL - 11 IS - 4 ER - TY - JOUR A1 - Lamatsch, Dunja K. A1 - Adolfsson, Sofia A1 - Senior, Alistair M. A1 - Christiansen, Guntram A1 - Pichler, Maria A1 - Ozaki, Yuichi A1 - Smeds, Linnea A1 - Schartl, Manfred A1 - Nakagawa, Shinichi T1 - A transcriptome derived female-specific marker from the invasive Western mosquitofish (Gambusia affinis) JF - PLoS ONE N2 - Sex-specific markers are a prerequisite for understanding reproductive biology, genetic factors involved in sex differences, mechanisms of sex determination, and ultimately the evolution of sex chromosomes. The Western mosquitofish, Gambusia affinis, may be considered a model species for sex-chromosome evolution, as it displays female heterogamety (ZW/ZZ), and is also ecologically interesting as a worldwide invasive species. Here, de novo RNA-sequencing on the gonads of sexually mature G. affinis was used to identify contigs that were highly transcribed in females but not in males (i.e., transcripts with ovary-specific expression). Subsequently, 129 primer pairs spanning 79 contigs were tested by PCR to identify sex-specific transcripts. Of those primer pairs, one female-specific DNA marker was identified, Sanger sequenced and subsequently validated in 115 fish. Sequence analyses revealed a high similarity between the identified sex-specific marker and the 3' UTR of the aminomethyl transferase (amt) gene of the closely related platyfish (Xiphophorus maculatus). This is the first time that RNA-seq has been used to successfully characterize a sex-specific marker in a fish species in the absence of a genome map. Additionally, the identified sex-specific marker represents one of only a handful of such markers in fishes. KW - sex chromosome evolution KW - linkage map KW - determination locus KW - poeciliid fishes KW - heterogamety KW - Cynoglossus semilaevis KW - determining genes KW - Y chromosome KW - sequence alignment Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-144004 VL - 10 IS - 2 ER - TY - JOUR A1 - Kang, Ji Hyoun A1 - Manousaki, Tereza A1 - Franchini, Paolo A1 - Kneitz, Susanne A1 - Schartl, Manfred A1 - Meyer, Axel T1 - Transcriptomics of two evolutionary novelties: how to make a sperm-transfer organ out of an anal fin and a sexually selected "sword" out of a caudal fin JF - Ecology and Evolution N2 - Swords are exaggerated male ornaments of swordtail fishes that have been of great interest to evolutionary biologists ever since Darwin described them in the Descent of Man (1871). They are a novel sexually selected trait derived from modified ventral caudal fin rays and are only found in the genus Xiphophorus. Another phylogenetically more widespread and older male trait is the gonopodium, an intromittent organ found in all poeciliid fishes, that is derived from a modified anal fin. Despite many evolutionary and behavioral studies on both traits, little is known so far about the molecular mechanisms underlying their development. By investigating transcriptomic changes (utilizing a RNA-Seq approach) in response to testosterone treatment in the swordtail fish, Xiphophorus hellerii, we aimed to better understand the architecture of the gene regulatory networks underpinning the development of these two evolutionary novelties. Large numbers of genes with tissue-specific expression patterns were identified. Among the sword genes those involved in embryonic organ development, sexual character development and coloration were highly expressed, while in the gonopodium rather more morphogenesis-related genes were found. Interestingly, many genes and genetic pathways are shared between both developing novel traits derived from median fins: the sword and the gonopodium. Our analyses show that a larger set of gene networks was co-opted during the development and evolution of the older gonopodium than in the younger, and morphologically less complex trait, the sword. We provide a catalog of candidate genes for future efforts to dissect the development of those sexually selected exaggerated male traits in swordtails. KW - mouse testis differentiation KW - fishes Xiphophorus KW - beetle horns KW - gonopodium KW - RNA-Seq KW - swordtails KW - Xiphophorus KW - key innovation KW - male-specific traits KW - Co-option KW - genus Xiphophorus KW - hybrid origin KW - Drosophila melanogaster KW - expression analysis KW - cell proliferation KW - preexisting bias KW - sex combs Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-144139 VL - 5 IS - 4 ER - TY - JOUR A1 - Simon, Christian M. A1 - Rauskolb, Stefanie A1 - Gunnersen, Jennifer M. A1 - Holtmann, Bettina A1 - Drepper, Carsten A1 - Dombert, Benjamin A1 - Braga, Massimiliano A1 - Wiese, Stefan A1 - Jablonka, Sibylle A1 - Pühringer, Dirk A1 - Zielasek, Jürgen A1 - Hoeflich, Andreas A1 - Silani, Vincenzo A1 - Wolf, Eckhard A1 - Kneitz, Susanne A1 - Sommer, Claudia A1 - Toyka, Klaus V. A1 - Sendtner, Michael T1 - Dysregulated IGFBP5 expression causes axon degeneration and motoneuron loss in diabetic neuropathy JF - Acta Neuropathologica N2 - Diabetic neuropathy (DNP), afflicting sensory and motor nerve fibers, is a major complication in diabetes.The underlying cellular mechanisms of axon degeneration are poorly understood. IGFBP5, an inhibitory binding protein for insulin-like growth factor 1 (IGF1) is highly up-regulated in nerve biopsies of patients with DNP. We investigated the pathogenic relevance of this finding in transgenic mice overexpressing IGFBP5 in motor axons and sensory nerve fibers. These mice develop motor axonopathy and sensory deficits similar to those seen in DNP. Motor axon degeneration was also observed in mice in which the IGF1 receptor(IGF1R) was conditionally depleted in motoneurons, indicating that reduced activity of IGF1 on IGF1R in motoneurons is responsible for the observed effect. These data provide evidence that elevated expression of IGFBP5 in diabetic nerves reduces the availability of IGF1 for IGF1R on motor axons, thus leading to progressive neurodegeneration. Inhibition of IGFBP5 could thus offer novel treatment strategies for DNP. KW - Motor nerve biopsy KW - Diabetic polyneuropathy KW - Neuropathy KW - Neurotrophic factors KW - Axonal degeneration Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-154569 VL - 130 SP - 373 EP - 387 ER - TY - JOUR A1 - Karulin, Alexey Y. A1 - Karacsony, Kinga A1 - Zhang, Wenji A1 - Targoni, Oleg S. A1 - Moldova, Ioana A1 - Dittrich, Marcus A1 - Sundararaman, Srividya A1 - Lehmann, Paul V. T1 - ELISPOTs produced by CD8 and CD4 cells follow Log Normal size distribution permitting objective counting JF - Cells N2 - Each positive well in ELISPOT assays contains spots of variable sizes that can range from tens of micrometers up to a millimeter in diameter. Therefore, when it comes to counting these spots the decision on setting the lower and the upper spot size thresholds to discriminate between non-specific background noise, spots produced by individual T cells, and spots formed by T cell clusters is critical. If the spot sizes follow a known statistical distribution, precise predictions on minimal and maximal spot sizes, belonging to a given T cell population, can be made. We studied the size distributional properties of IFN-γ, IL-2, IL-4, IL-5 and IL-17 spots elicited in ELISPOT assays with PBMC from 172 healthy donors, upon stimulation with 32 individual viral peptides representing defined HLA Class I-restricted epitopes for CD8 cells, and with protein antigens of CMV and EBV activating CD4 cells. A total of 334 CD8 and 80 CD4 positive T cell responses were analyzed. In 99.7% of the test cases, spot size distributions followed Log Normal function. These data formally demonstrate that it is possible to establish objective, statistically validated parameters for counting T cell ELISPOTs. KW - ELISPOT KW - software KW - IFN-γ KW - IL-17 KW - T cells KW - Normal Distribution KW - spot size KW - gating KW - cytokines KW - IL-2 KW - IL-4 KW - IL-5 KW - CD8 KW - CD4 Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-149648 VL - 4 IS - 1 ER - TY - JOUR A1 - García-Martínez, Jorge A1 - Brunk, Michael A1 - Avalos, Javier A1 - Terpitz, Ulrich T1 - The CarO rhodopsin of the fungus Fusarium fujikuroi is a light-driven proton pump that retards spore germination JF - Scientific Reports N2 - Rhodopsins are membrane-embedded photoreceptors found in all major taxonomic kingdoms using retinal as their chromophore. They play well-known functions in different biological systems, but their roles in fungi remain unknown. The filamentous fungus Fusarium fujikuroi contains two putative rhodopsins, CarO and OpsA. The gene carO is light-regulated, and the predicted polypeptide contains all conserved residues required for proton pumping. We aimed to elucidate the expression and cellular location of the fungal rhodopsin CarO, its presumed proton-pumping activity and the possible effect of such function on F. fujikuroi growth. In electrophysiology experiments we confirmed that CarO is a green-light driven proton pump. Visualization of fluorescent CarO-YFP expressed in F. fujikuroi under control of its native promoter revealed higher accumulation in spores (conidia) produced by light-exposed mycelia. Germination analyses of conidia from carO\(^{-}\) mutant and carO\(^{+}\) control strains showed a faster development of light-exposed carO-germlings. In conclusion, CarO is an active proton pump, abundant in light-formed conidia, whose activity slows down early hyphal development under light. Interestingly, CarO-related rhodopsins are typically found in plant-associated fungi, where green light dominates the phyllosphere. Our data provide the first reliable clue on a possible biological role of a fungal rhodopsin. KW - microbial rhodopsins KW - intracellular pH KW - membrane proteins KW - mutants KW - virulence KW - channelrhodopsin-2 KW - growth KW - gene KW - expression KW - bacteriorhodopsin Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-149049 VL - 5 IS - 7798 ER - TY - JOUR A1 - Leikam, C A1 - Hufnagel, AL A1 - Otto, C A1 - Murphy, DJ A1 - Mühling, B A1 - Kneitz, S A1 - Nanda, I A1 - Schmid, M A1 - Wagner, TU A1 - Haferkamp, S A1 - Bröcker, E-B A1 - Schartl, M A1 - Meierjohann, S T1 - In vitro evidence for senescent multinucleated melanocytes as a source for tumor-initiating cells JF - Cell Death and Disease N2 - Oncogenic signaling in melanocytes results in oncogene-induced senescence (OIS), a stable cell-cycle arrest frequently characterized by a bi-or multinuclear phenotype that is considered as a barrier to cancer progression. However, the long-sustained conviction that senescence is a truly irreversible process has recently been challenged. Still, it is not known whether cells driven into OIS can progress to cancer and thereby pose a potential threat. Here, we show that prolonged expression of the melanoma oncogene N-RAS\(^{61K}\) in pigment cells overcomes OIS by triggering the emergence of tumor-initiating mononucleated stem-like cells from senescent cells. This progeny is dedifferentiated, highly proliferative, anoikis-resistant and induces fast growing, metastatic tumors. Our data describe that differentiated cells, which are driven into senescence by an oncogene, use this senescence state as trigger for tumor transformation, giving rise to highly aggressive tumor-initiating cells. These observations provide the first experimental in vitro evidence for the evasion of OIS on the cellular level and ensuing transformation. KW - reactive oxygen KW - human melanoma KW - MITF KW - cancer KW - skin KW - DNA damage KW - kappa-B KW - oncogene-induced senescence KW - cellular senescence Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-148718 VL - 6 IS - e1711 ER - TY - JOUR A1 - Ehmann, Nadine A1 - Sauer, Markus A1 - Kittel, Robert J. T1 - Super-resolution microscopy of the synaptic active zone JF - Frontiers in Cellular Neuroscience N2 - Brain function relies on accurate information transfer at chemical synapses. At the presynaptic active zone (AZ) a variety of specialized proteins are assembled to complex architectures, which set the basis for speed, precision and plasticity of synaptic transmission. Calcium channels are pivotal for the initiation of excitation-secretion coupling and, correspondingly, capture a central position at the AZ. Combining quantitative functional studies with modeling approaches has provided predictions of channel properties, numbers and even positions on the nanometer scale. However, elucidating the nanoscopic organization of the surrounding protein network requires direct ultrastructural access. Without this information, knowledge of molecular synaptic structure-function relationships remains incomplete. Recently, super-resolution microscopy (SRM) techniques have begun to enter the neurosciences. These approaches combine high spatial resolution with the molecular specificity of fluorescence microscopy. Here, we discuss how SRM can be used to obtain information on the organization of AZ proteins KW - excitation-secretion coupling KW - Ca\(^{2+}\) channels KW - structure-function relationships KW - super-resolution microscopy KW - active zone KW - presynaptic calcium KW - neurotransmitter release Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-148997 VL - 9 IS - 7 ER - TY - JOUR A1 - Herweg, Jo-Ana A1 - Hansmeier, Nicole A1 - Otto, Andreas A1 - Geffken, Anna C. A1 - Subbarayal, Prema A1 - Prusty, Bhupesh K. A1 - Becher, Dörte A1 - Hensel, Michael A1 - Schaible, Ulrich E. A1 - Rudel, Thomas A1 - Hilbi, Hubert T1 - Purification and proteomics of pathogen-modified vacuoles and membranes JF - Frontiers in Cellular and Infection Microbiology N2 - Certain pathogenic bacteria adopt an intracellular lifestyle and proliferate in eukaryotic host cells. The intracellular niche protects the bacteria from cellular and humoral components of the mammalian immune system, and at the same time, allows the bacteria to gain access to otherwise restricted nutrient sources. Yet, intracellular protection and access to nutrients comes with a price, i.e., the bacteria need to overcome cell-autonomous defense mechanisms, such as the bactericidal endocytic pathway. While a few bacteria rupture the early phagosome and escape into the host cytoplasm, most intracellular pathogens form a distinct, degradation-resistant and replication-permissive membranous compartment. Intracellular bacteria that form unique pathogen vacuoles include Legionella, Mycobacterium, Chlamydia, Simkania, and Salmonella species. In order to understand the formation of these pathogen niches on a global scale and in a comprehensive and quantitative manner, an inventory of compartment-associated host factors is required. To this end, the intact pathogen compartments need to be isolated, purified and biochemically characterized. Here, we review recent progress on the isolation and purification of pathogen-modified vacuoles and membranes, as well as their proteomic characterization by mass spectrometry and different validation approaches. These studies provide the basis for further investigations on the specific mechanisms of pathogen-driven compartment formation. KW - spectrometry-based proteomics KW - Mycobacterium tuberculosis KW - Chlamydia KW - Salmonella KW - bacterium Legionella pneumophila KW - endocytic multivesicular bodies KW - phagosome maturation arrest KW - III secretion system KW - endoplasmic reticulum KW - Chlamydia trachomatis KW - Simkania negevensis KW - intracellular bacteria KW - host pathogen interactions KW - immuno-magnetic purification KW - Legionella KW - Mycobacterium KW - Simkania KW - pathogen vacuole Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-151823 VL - 5 IS - 48 ER - TY - JOUR A1 - Morriswood, Brooke T1 - Form, fabric, and function of a flagellum-associated cytoskeletal structure. JF - Cells N2 - Trypanosoma brucei is a uniflagellated protist and the causative agent of African trypanosomiasis, a neglected tropical disease. The single flagellum of T. brucei is essential to a number of cellular processes such as motility, and has been a longstanding focus of scientific enquiry. A number of cytoskeletal structures are associated with the flagellum in T. brucei, and one such structure—a multiprotein complex containing the repeat motif protein TbMORN1—is the focus of this review. The TbMORN1-containing complex, which was discovered less than ten years ago, is essential for the viability of the mammalian-infective form of T. brucei. The complex has an unusual asymmetric morphology, and is coiled around the flagellum to form a hook shape. Proteomic analysis using the proximity-dependent biotin identification (BioID) technique has elucidated a number of its components. Recent work has uncovered a role for TbMORN1 in facilitating protein entry into the cell, thus providing a link between the cytoskeleton and the endomembrane system. This review summarises the extant data on the complex, highlights the outstanding questions for future enquiry, and provides speculation as to its possible role in a size-exclusion mechanism for regulating protein entry. The review additionally clarifies the nomenclature associated with this topic, and proposes the adoption of the term “hook complex” to replace the former name “bilobe” to describe the complex. KW - BioID KW - Trypanosoma brucei KW - cytoskeleton KW - TbMORN1 KW - MORN-repeat Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-149467 VL - 4 IS - 4 ER - TY - JOUR A1 - Dühring, Sybille A1 - Germerodt, Sebastian A1 - Skerka, Christine A1 - Zipfel, Peter F. A1 - Dandekar, Thomas A1 - Schuster, Stefan T1 - Host-pathogen interactions between the human innate immune system and Candida albicans - understanding and modeling defense and evasion strategies JF - Frontiers in Microbiology N2 - The diploid, polymorphic yeast Candida albicans is one of the most important human pathogenic fungi. C. albicans can grow, proliferate and coexist as a commensal on or within the human host for a long time. However, alterations in the host environment can render C. albicans virulent. In this review, we describe the immunological cross-talk between C. albicans and the human innate immune system. We give an overview in form of pairs of human defense strategies including immunological mechanisms as well as general stressors such as nutrient limitation, pH, fever etc. and the corresponding fungal response and evasion mechanisms. Furthermore, Computational Systems Biology approaches to model and investigate these complex interactions are highlighted with a special focus on game-theoretical methods and agent-based models. An outlook on interesting questions to be tackled by Systems Biology regarding entangled defense and evasion mechanisms is given. KW - agent-based model KW - antimicrobial peptides KW - fungal pathogens KW - Candida albicans KW - immunological cross-talk KW - beta-lactamase inhibition KW - in vitro KW - biomaterial surfaces KW - biofilm formation KW - dendritic cells KW - infection KW - resistance KW - human immune system KW - host-pathogen interaction KW - computational systems biology KW - defense and evasion strategies Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-151621 VL - 6 IS - 625 ER - TY - JOUR A1 - Frank, Daniel O. A1 - Dengjel, Jörn A1 - Wilfling, Florian A1 - Kozjak-Pavlovic, Vera A1 - Häcker, Georg A1 - Weber, Arnim T1 - The Pro-Apoptotic BH3-Only Protein Bim Interacts with Components of the Translocase of the Outer Mitochondrial Membrane (TOM) JF - PLoS ONE N2 - The pro-apoptotic Bcl-2-family protein Bim belongs to the BH3-only proteins known as initiators of apoptosis. Recent data show that Bim is constitutively inserted in the outer mitochondrial membrane via a C-terminal transmembrane anchor from where it can activate the effector of cytochrome c-release, Bax. To identify regulators of Bim-activity, we conducted a search for proteins interacting with Bim at mitochondria. We found an interaction of Bim with Tom70, Tom20 and more weakly with Tom40, all components of the Translocase of the Outer Membrane (TOM). In vitro import assays performed on tryptically digested yeast mitochondria showed reduced Bim insertion into the outer mitochondrial membrane (OMM) indicating that protein receptors may be involved in the import process. However, RNAi against components of TOM (Tom40, Tom70, Tom22 or Tom20) by siRNA, individually or in combination, did not consistently change the amount of Bim on HeLa mitochondria, either at steady state or upon de novo-induction. In support of this, the individual or combined knockdowns of TOM receptors also failed to alter the susceptibility of HeLa cells to Bim-induced apoptosis. In isolated yeast mitochondria, lack of Tom70 or the TOM-components Tom20 or Tom22 alone did not affect the import of Bim into the outer mitochondrial membrane. In yeast, expression of Bim can sensitize the cells to Bax-dependent killing. This sensitization was unaffected by the absence of Tom70 or by an experimental reduction in Tom40. Although thus the physiological role of the Bim-TOM-interaction remains unclear, TOM complex components do not seem to be essential for Bim insertion into the OMM. Nevertheless, this association should be noted and considered when the regulation of Bim in other cells and situations is investigated. KW - bax KW - preproteins KW - phosphorylation KW - proteomics KW - degradation KW - cells KW - family KW - import KW - BH3 domains KW - Bcl-2 proteins Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-143301 VL - 10 IS - 4 ER - TY - JOUR A1 - Dandekar, Thomas A1 - Eisenreich, Wolfgang T1 - Host-adapted metabolism and its regulation in bacterial pathogens JF - Frontiers in Cellular and Infection Microbiology N2 - No abstract available. KW - bacterial pathogens KW - enteric pathogens KW - metabolism KW - host-pathogen adaption KW - isotopolog profiling Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-196876 SN - 2235-2988 VL - 5 IS - 28 ER - TY - JOUR A1 - Dandekar, Thomas A1 - Fieselmann, Astrid A1 - Fischer, Eva A1 - Popp, Jasmin A1 - Hensel, Michael A1 - Noster, Janina T1 - Salmonella - how a metabolic generalist adopts an intracellular lifestyle during infection JF - Frontiers in Cellular and Infection Microbiology N2 - The human-pathogenic bacterium Salmonella enterica adjusts and adapts to different environments while attempting colonization. In the course of infection nutrient availabilities change drastically. New techniques, "-omics" data and subsequent integration by systems biology improve our understanding of these changes. We review changes in metabolism focusing on amino acid and carbohydrate metabolism. Furthermore, the adaptation process is associated with the activation of genes of the Salmonella pathogenicity islands (SPIs). Anti-infective strategies have to take these insights into account and include metabolic and other strategies. Salmonella infections will remain a challenge for infection biology. KW - enterica serovar Typhimurium KW - bacterial invasion KW - mouse model KW - defenses KW - regulation KW - "-omics" KW - virulence KW - Salmonella-containing vacuole (SCV) KW - metabolism KW - nitric oxide Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-149029 VL - 4 IS - 191 ER - TY - JOUR A1 - Martin, Emily A. A1 - Reineking, Björn A1 - Seo, Bumsuk A1 - Steffan-Dewenter, Ingolf T1 - Pest control of aphids depends on landscape complexity and natural enemy interactions JF - PeerJ N2 - Aphids are a major concern in agricultural crops worldwide, and control by natural enemies is an essential component of the ecological intensification of agriculture. Although the complexity of agricultural landscapes is known to influence natural enemies of pests, few studies have measured the degree of pest control by different enemy guilds across gradients in landscape complexity. Here, we use multiple natural-enemy exclosures replicated in 18 fields across a gradient in landscape complexity to investigate (1) the strength of natural pest control across landscapes, measured as the difference between pest pressure in the presence and in the absence of natural enemies; (2) the differential contributions of natural enemy guilds to pest control, and the nature of their interactions across landscapes. We show that natural pest control of aphids increased up to six-fold from simple to complex landscapes. In the absence of pest control, aphid population growth was higher in complex than simple landscapes, but was reduced by natural enemies to similar growth rates across all landscapes. The effects of enemy guilds were landscape-dependent. Particularly in complex landscapes, total pest control was supplied by the combined contribution of flying insects and ground-dwellers. Birds had little overall impact on aphid control. Despite evidence for intraguild predation of flying insects by ground-dwellers and birds, the overall effect of enemy guilds on aphid control was complementary. Understanding pest control services at large spatial scales is critical to increase the success of ecological intensification schemes. Our results suggest that, where aphids are the main pest of concern, interactions between natural enemies are largely complementary and lead to a strongly positive effect of landscape complexity on pest control. Increasing the availability of seminatural habitats in agricultural landscapes may thus benefit not only natural enemies, but also the effectiveness of aphid natural pest control. KW - insect populations KW - metaanalysis KW - biodiversity-ecosystem functioning KW - cabbage Brassica oleracea var. capitata KW - proportion of seminatural habitat KW - South Korea KW - land use intensification KW - trophic interactions KW - agroecosystems KW - biological control KW - agricultural landscapes KW - pest KW - biodiversity KW - herbivores Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-148393 VL - 3 IS - e1095 ER - TY - JOUR A1 - Joschinski, Jens A1 - Hovestadt, Thomas A1 - Krauss, Jochen T1 - Coping with shorter days: do phenology shifts constrain aphid fitness? JF - PeerJ N2 - Climate change can alter the phenology of organisms. It may thus lead seasonal organisms to face different day lengths than in the past, and the fitness consequences of these changes are as yet unclear. To study such effects, we used the pea aphid Acyrthosiphon pisum as a model organism, as it has obligately asexual clones which can be used to study day length effects without eliciting a seasonal response. We recorded life-history traits under short and long days, both with two realistic temperature cycles with means differing by 2 °C. In addition, we measured the population growth of aphids on their host plant Pisum sativum. We show that short days reduce fecundity and the length of the reproductive period of aphids. Nevertheless, this does not translate into differences at the population level because the observed fitness costs only become apparent late in the individual's life. As expected, warm temperature shortens the development time by 0.7 days/°C, leading to faster generation times. We found no interaction of temperature and day length. We conclude that day length changes cause only relatively mild costs, which may not decelerate the increase in pest status due to climate change. KW - Homoptera aphididae KW - clock reproduction ecology KW - phenotypic plasticity KW - phenology shifts KW - insect timing KW - physiological constraints KW - day length KW - circadian rhythms KW - Acyrthosiphon pisum KW - climate change Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-148382 VL - 3 IS - e1103 ER - TY - JOUR A1 - Kleijn, David A1 - Winfree, Rachael A1 - Bartomeus, Ignasi A1 - Carvalheiro, Luísa G. A1 - Henry, Mickael A1 - Isaacs, Rufus A1 - Klein, Alexandra-Maria A1 - Kremen, Claire A1 - M'Gonigle, Leithen K. A1 - Rader, Romina A1 - Ricketts, Taylor H. A1 - Williams, Neal M. A1 - Adamson, Nancy Lee A1 - Ascher, John S. A1 - Báldi, András A1 - Batáry, Péter A1 - Benjamin, Faye A1 - Biesmeijer, Jacobus C. A1 - Blitzer, Eleanor J. A1 - Bommarco, Riccardo A1 - Brand, Mariette R. A1 - Bretagnolle, Vincent A1 - Button, Lindsey A1 - Cariveau, Daniel P. A1 - Chifflet, Rémy A1 - Colville, Jonathan F. A1 - Danforth, Bryan N. A1 - Elle, Elizabeth A1 - Garratt, Michael P. D. A1 - Herzog, Felix A1 - Holzschuh, Andrea A1 - Howlett, Brad G. A1 - Jauker, Frank A1 - Jha, Shalene A1 - Knop, Eva A1 - Krewenka, Kristin M. A1 - Le Féon, Violette A1 - Mandelik, Yael A1 - May, Emily A. A1 - Park, Mia G. A1 - Pisanty, Gideon A1 - Reemer, Menno A1 - Riedinger, Verena A1 - Rollin, Orianne A1 - Rundlöf, Maj A1 - Sardiñas, Hillary S. A1 - Scheper, Jeroen A1 - Sciligo, Amber R. A1 - Smith, Henrik G. A1 - Steffan-Dewenter, Ingolf A1 - Thorp, Robbin A1 - Tscharntke, Teja A1 - Verhulst, Jort A1 - Viana, Blandina F. A1 - Vaissière, Bernard E. A1 - Veldtman, Ruan A1 - Ward, Kimiora L. A1 - Westphal, Catrin A1 - Potts, Simon G. T1 - Delivery of crop pollination services is an insufficient argument for wild pollinator conservation JF - Nature Communications N2 - There is compelling evidence that more diverse ecosystems deliver greater benefits to people, and these ecosystem services have become a key argument for biodiversity conservation. However, it is unclear how much biodiversity is needed to deliver ecosystem services in a cost- effective way. Here we show that, while the contribution of wild bees to crop production is significant, service delivery is restricted to a limited subset of all known bee species. Across crops, years and biogeographical regions, crop-visiting wild bee communities are dominated by a small number of common species, and threatened species are rarely observed on crops. Dominant crop pollinators persist under agricultural expansion and many are easily enhanced by simple conservation measures, suggesting that cost- effective management strategies to promote crop pollination should target a different set of species than management strategies to promote threatened bees. Conserving the biological diversity of bees therefore requires more than just ecosystem-service-based arguments. KW - ecosystem services KW - european countries KW - abundance KW - native bees KW - biodiversity conservation KW - plant diversity KW - fruit set KW - productivity KW - decline KW - pollen Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-151879 VL - 6 IS - 7414 ER - TY - JOUR A1 - Appel, Mirjam A1 - Scholz, Claus-Jürgen A1 - Müller, Tobias A1 - Dittrich, Marcus A1 - König, Christian A1 - Bockstaller, Marie A1 - Oguz, Tuba A1 - Khalili, Afshin A1 - Antwi-Adjei, Emmanuel A1 - Schauer, Tamas A1 - Margulies, Carla A1 - Tanimoto, Hiromu A1 - Yarali, Ayse T1 - Genome-Wide Association Analyses Point to Candidate Genes for Electric Shock Avoidance in Drosophila melanogaster JF - PLoS ONE N2 - Electric shock is a common stimulus for nociception-research and the most widely used reinforcement in aversive associative learning experiments. Yet, nothing is known about the mechanisms it recruits at the periphery. To help fill this gap, we undertook a genome-wide association analysis using 38 inbred Drosophila melanogaster strains, which avoided shock to varying extents. We identified 514 genes whose expression levels and/or sequences covaried with shock avoidance scores. We independently scrutinized 14 of these genes using mutants, validating the effect of 7 of them on shock avoidance. This emphasizes the value of our candidate gene list as a guide for follow-up research. In addition, by integrating our association results with external protein-protein interaction data we obtained a shock avoidance- associated network of 38 genes. Both this network and the original candidate list contained a substantial number of genes that affect mechanosensory bristles, which are hairlike organs distributed across the fly's body. These results may point to a potential role for mechanosensory bristles in shock sensation. Thus, we not only provide a first list of candidate genes for shock avoidance, but also point to an interesting new hypothesis on nociceptive mechanisms. KW - functional analysis KW - disruption project KW - natural variation KW - complex traits KW - networks KW - behavior KW - flies KW - temperature KW - genetics KW - painful Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-152006 VL - 10 IS - 5 ER -