TY - JOUR A1 - Wolf, Beat A1 - Kuonen, Pierre A1 - Dandekar, Thomas A1 - Atlan, David T1 - DNAseq workflow in a diagnostic context and an example of a user friendly implementation JF - BioMed Research International N2 - Over recent years next generation sequencing (NGS) technologies evolved from costly tools used by very few, to a much more accessible and economically viable technology. Through this recently gained popularity, its use-cases expanded from research environments into clinical settings. But the technical know-how and infrastructure required to analyze the data remain an obstacle for a wider adoption of this technology, especially in smaller laboratories. We present GensearchNGS, a commercial DNAseq software suite distributed by Phenosystems SA. The focus of GensearchNGS is the optimal usage of already existing infrastructure, while keeping its use simple. This is achieved through the integration of existing tools in a comprehensive software environment, as well as custom algorithms developed with the restrictions of limited infrastructures in mind. This includes the possibility to connect multiple computers to speed up computing intensive parts of the analysis such as sequence alignments. We present a typical DNAseq workflow for NGS data analysis and the approach GensearchNGS takes to implement it. The presented workflow goes from raw data quality control to the final variant report. This includes features such as gene panels and the integration of online databases, like Ensembl for annotations or Cafe Variome for variant sharing. KW - next generation sequencing KW - genome browser KW - mutation KW - algorithm KW - database KW - format KW - discovery KW - exome KW - variants KW - alignment Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-144527 IS - 403497 ER - TY - JOUR A1 - Wolf, Annette A1 - Akrap, Nina A1 - Marg, Berenice A1 - Galliardt, Helena A1 - Heiligentag, Martyna A1 - Humpert, Fabian A1 - Sauer, Markus A1 - Kaltschmidt, Barbara A1 - Kaltschmidt, Christian A1 - Seidel, Thorsten T1 - Elements of Transcriptional Machinery Are Compatible among Plants and Mammals JF - PLoS ONE N2 - In the present work, the objective has been to analyse the compatibility of plant and human transcriptional machinery. The experiments revealed that nuclear import and export are conserved among plants and mammals. Further it has been shown that transactivation of a human promoter occurs by human transcription factor NF-\(\kappa\) B in plant cells, demonstrating that the transcriptional machinery is highly conserved in both kingdoms. Functionality was also seen for regulatory elements of NF-\(\kappa\) B such as its inhibitor I\(\kappa\)B isoform \(\alpha\) that negatively regulated the transactivation activity of the p50/RelA heterodimer by interaction with NF-\(\kappa\)B in plant cells. Nuclear export of RelA could be demonstrated by FRAP-measurements so that RelA shows nucleo-cytoplasmic shuttling as reported for RelA in mammalian cells. The data reveals the high level of compatibility of human transcriptional elements with the plant transcriptional machinery. Thus, Arabidopsis thaliana mesophyll protoplasts might provide a new heterologous expression system for the investigation of the human NF-\(\kappa\)B signaling pathways. The system successfully enabled the controlled manipulation of NF-\(\kappa\)B activity. We suggest the plant protoplast system as a tool for reconstitution and analyses of mammalian pathways and for direct observation of responses to e. g. pharmaceuticals. The major advantage of the system is the absence of interference with endogenous factors that affect and crosstalk with the pathway. KW - complexes KW - in vivo KW - DNA-binding KW - nuclear proe KW - gene expression KW - NF-KAPPA-B KW - RNA-binding protein KW - alpha KW - inflammation KW - homodimers Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-131203 VL - 8 IS - 1 ER - TY - JOUR A1 - Wohlwend, Michael R. A1 - Craven, Dylan A1 - Weigelt, Patrick A1 - Seebens, Hanno A1 - Winter, Marten A1 - Kreft, Holger A1 - Zurell, Damaris A1 - Sarmento Cabral, Juliano A1 - Essl, Franz A1 - van Kleunen, Mark A1 - Pergl, Jan A1 - Pyšek, Petr A1 - Knight, Tiffany M. T1 - Anthropogenic and environmental drivers shape diversity of naturalized plants across the Pacific JF - Diversity and Distributions N2 - Aim The Pacific exhibits an exceptional number of naturalized plant species, but the drivers of this high diversity and the associated compositional patterns remain largely unknown. Here, we aim to (a) improve our understanding of introduction and establishment processes and (b) evaluate whether this information is sufficient to create scientific conservation tools, such as watchlists. Location Islands in the Pacific Ocean, excluding larger islands such as New Zealand, Japan, the Philippines and Indonesia. Methods We combined information from the most up‐to‐date data sources to quantify naturalized plant species richness and turnover across island groups and investigate the effects of anthropogenic, biogeographic and climate drivers on these patterns. In total, we found 2,672 naturalized plant species across 481 islands and 50 island groups, with a total of 11,074 records. Results Most naturalized species were restricted to few island groups, and most island groups have a low number of naturalized species. Island groups with few naturalized species were characterized by a set of widespread naturalized species. Several plant families that contributed many naturalized species globally also did so in the Pacific, particularly Fabaceae and Poaceae. However, many families were significantly over‐ or under‐represented in the Pacific naturalized flora compared to other regions of the world. Naturalized species richness increased primarily with increased human activity and island altitude/area, whereas similarity between island groups in temperature along with richness differences was most important for beta diversity. Main conclusions The distribution and richness of naturalized species can be explained by a small set of drivers. The Pacific region contains many naturalized plant species also naturalized in other regions in the world, but our results highlight key differences such as a stronger role of anthropogenic drivers in shaping diversity patterns. Our results establish a basis for predicting and preventing future naturalizations in a threatened biodiversity hotspot. KW - anthropogenic drivers KW - beta diversity KW - island biogeography KW - naturalized species KW - Pacific Ocean KW - plant invasion Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-239925 VL - 27 IS - 6 SP - 1120 EP - 1133 ER - TY - THES A1 - Wittmann, Stefanie T1 - LOH- und Expressionsanalysen zur Identifikation neuer prognostischer Marker in Wilms Tumoren T1 - LOH and expression analyses for the identification of new prognostic markers in Wilms tumors N2 - Der Wilms Tumor (WT), auch Nephroblastom genannt, zählt zu den im Kindesalter am häufigsten auftretenden malignen Tumoren und entsteht meist unilateral (90 – 95 %) und sporadisch (98 – 99 %). Leider sind bis heute die molekularen Ursachen, die zur Entwicklung dieser Tumoren führen nur unzureichend aufgeklärt. So werden bisher nur drei Gene mit dem Auftreten von WT in Verbindung gebracht: WT1, CTNNB1 und WTx. Während WT1 und CTNNB1 jeweils Mutationsraten von etwa 10 – 15 % aufweisen, die zudem häufig gemeinsam vorliegen, werden für WTx Mutationsraten von etwa 30 % beobachtet. Die genetischen Alterationen der anderen Tumoren sind noch immer komplett unbekannt. Ziel dieser Arbeit war aus diesem Grund die Identifikation von relevanten Regionen und Genen, die an der Entstehung bzw. dem klinischen Fortschreiten von Wilms Tumoren beteiligt sind. Zusätzlich sollten weitere Untersuchungen zur Einschätzung ihres prognostischen Potenzials dienen. In einem ersten Ansatz wurden die Chromosomenbereiche 11q und 16q in einer großen Anzahl von Wilms Tumoren auf LOH (=loss of heterozygosity), d.h. den (partiellen) Verlust von genetischem Material, untersucht. In beiden Fällen wurden erhöhte LOH-Raten von etwa 20 % beobachtet, jedoch war keine Eingrenzung der relevanten Regionen möglich, da Allelverluste nicht stets ab einem bestimmten Marker beobachtet wurden. Ein Vergleich mit der Histologie ergab signifikante Assoziationen der Allelverluste mit anaplastischen und Mischtyp-Tumoren (nur für LOH 11q), wohingegen kaum LOHs in epithelialen und stromareichen Tumoren festgestellt wurden. Somit scheinen auf 11q und 16q Gene vorzuliegen, die einerseits die Differenzierung in Epithel und Stroma begünstigen oder andererseits ein blastemreiches und anaplastisches Erscheinungsbild verhindern. Jedoch könnte auch die Assoziation von bestimmten Subtypen mit LOH 11q und 16q auf eine Entstehung aus unterschiedlichen Zellen hindeuten. Weiterhin war das Auftreten von LOH, v.a. wenn jeweils der komplette Chromosomenarm betroffen war, mit einem erhöhten Rezidiv- und Sterberisiko (nur LOH 11q) verbunden. Somit konnte gezeigt werden, dass LOH-Untersuchungen auf 11q und 16q zur Identifikation von Hochrisikopatienten für die Entwicklung von Rezidiven bzw. erhöhter Mortalität eingesetzt werden können, wodurch eine individuelle Anpassung der Therapiemaßnahmen ermöglicht wird. In einem zweiten Ansatz wurden eine Reihe von bereits publizierten potenziellen Markergenen in einer großen Anzahl von Wilms Tumoren mit Hilfe der Realtime RT-PCR auf ihre Relevanz überprüft. Allen diesen Genen wurde zuvor eine Funktion bei der histologischen Klassifikation der Tumoren bzw. bei der Vorhersage bestimmter klinischer Verläufe zugeschrieben. Die univariate Analyse diente der Beurteilung der Relevanz einzelner Gene, wohingegen die multivariate Analyse zur Bestimmung von prognostischen Genkombinationen eingesetzt wurde. Anschließend erfolgte die Validierung mittels eines zweiten und unabhängigen Tumorsatzes. Auch wenn viele der bereits publizierten Marker und in der ersten Analyse erhaltenen Assoziationen in einem weiteren und unabhängigen Tumorsatz nicht verifizierbar waren, konnten dennoch einige frühere Ergebnisse repliziert und die Relevanz der entsprechenden Gene nachgewiesen werden. Neben der Verbindung der Repression von HEY2 und TRIM22 mit Hochrisikotumoren bzw. einer höheren Sterbewahrscheinlichkeit fanden sich schwach signifikante Assoziationen auch für die verminderte Expression von TRIM22 und VEGF mit der Histologie. Ebenso waren erhöhte Level von TERT und die Repression von TRIM22 mit der Entwicklung eines Rezidivs verbunden. Vor allem aber die Korrelation der Repression von HEY2 und VEGF sowie einer Überexpression von CA9 mit Rezidiven, Tumoren hoher Malignität oder primären Metastasen verweisen auf die Notwendigkeit, besonders die Hypoxie- und Angiogenese-Signalkaskaden in Wilms Tumoren zu untersuchen, um deren Einfluss v.a. auf das Fortschreiten und die Ausbreitung der Tumoren zu evaluieren. Auch wenn die multivariate Analyse nicht zu relevanten Genkombinationen führte, konnte hier dennoch eine schwache Assoziation der verminderten Expression von TOP2A und TRIM22 mit primären Metastasen oder einer erhöhten Mortalität, sowie der Überexpression von TERT mit der Rezidivbildung bestätigt werden. Interessanterweise stellte sich die Histologie, die derzeit das Hauptkriterium für die Risikoklassifikation darstellt, weder als geeigneter prognostischer Marker für die Beurteilung des Rezidiv- noch des Sterberisikos heraus. Somit sollten Realtime RT-PCR Analysen in Zukunft als weiterer Faktor zur Beurteilung des Rezidiv- und Sterberisikos eingesetzt werden, um eine individuelle Anpassung der Therapie zu ermöglichen. Basierend auf den Ergebnissen der Realtime RT-PCR Analyse wurde der Einfluss der Expression ausgewählter Gene auf Primärkulturen, die aus nativem Wilms Tumormaterial gewonnen wurden, untersucht. Nach der Überexpression von HEY2, EGR1, MYCN und TRIM22 wurden bei allen Zellen hohe Sterberaten beobachtet, v.a. bei HEY2 und EGR1. Leider konnte weder für HEY2 noch für EGR1 der Grund hierfür aufgeklärt werden, allerdings war bei EGR1 weder die Apoptose noch die Seneszenz beteiligt. Im Gegensatz hierzu wurde die Apoptose als entscheidender Mechanismus bei MYCN und v.a. TRIM22 ermittelt. Außerdem scheint bei MYCN ein großer Anteil an Zellen in die Seneszenz einzutreten. Auch wenn diese ersten Untersuchungen an Primärkulturen von Wilms Tumoren eindeutig die Relevanz dieser Gene für die Entwicklung bzw. das Fortschreiten der Tumoren bestätigten, so sind trotz alledem weitere Experimente v.a. in einer größeren Anzahl genetisch unterschiedlicher Primärkulturen nötig, um das endgültige Potenzial dieser Gene aufzuklären. N2 - Wilms tumor (WT), also called Nephroblastoma, belongs to the most common malignant tumors occurring in childhood. Most of these Wilms tumors develop unilaterally (90 – 95 %) and sporadically (98 – 99 %). Unfortunately, only little is known about the molecular background underlying their development with only three genes known so far: WT1, CTNNB1 and WTx. Mutations in WT1 and CTNNB1 occur only in a minor fraction of Wilms tumors of about 10 - 15 % and are often associated with each other, while mutations in WTx can be found in about 30 % of tumors. The genetic alterations of the other tumors are completely unknown. Hence, the aim of this thesis was to identify important regions and genes that are involved in Wilms tumor formation and/or progression and to further characterize their potential as markers for the prediction of certain clinical outcomes. First, chromosome arms 11q and 16q were screened for LOH (= loss of heterozygosity), which means the (partial) loss of the genome in a cell, in a large cohort of Wilms tumors. In both regions LOH rates of about 20 % were detected, but since allele losses did not always start at the same marker in the different tumors it was not possible to delimit any relevant subregions. Since there were significantly higher rates of allele loss in anaplastic and mixed-type (only 11q) tumors and almost no allele loss in epithelial and stromal tumors, 11q and 16q must contain genes that either facilitate the epithelial and stromal differentiation of cells or hamper the appearance of blastemal and anaplastic phenotypes. Otherwise, the obvious possibility to discriminate these histological subtypes by allele loss on 11q and 16q might be explained by a development from different precursor cells. Higher rates of LOH could also be linked to higher risks for relapse and death (11q only), especially when the whole chromosome arms were involved. Therefore, investigation of LOH on 11q and 16q may help to adjust the therapeutic regimens by identifying high-risk patients for relapse and death. A second approach was to reinvestigate the expression of a number of published marker genes in a larger set of Wilms tumors with a uniform method, the realtime RT-PCR. All of the genes were suggested to facilitate classification and/or prediction of certain clinical outcomes. Univariate analysis was performed to screen for relevant genes, followed by multivariate analysis to search for predictive gene combinations. Finally, validation of associations found in the first cohort was performed in a second and independent tumor set. Unfortunately, many of the previously published markers as well as associations of the first tumor set could not be verified in a new and independent tumor set. Nevertheless, it was possible to replicate the results of a number of genes and evidence their prognostic relevance. These included the repression of HEY2 and TRIM22 for high-risk tumors or mortality. Weaker correlations were verified for the repression of TRIM22 and VEGF with the histological risk and for overexpression of TERT and repression of TRIM22 with later relapse. Since the weaker expression of HEY2 and VEGF as well as the overexpression of CA9 was significantly linked to relapse, high malignant tumors or metastasis the hypoxia / angiogenesis pathways should be investigated in Wilms tumors especially with regard to the progression and spreading of tumors. Finally, multivariate analysis substantiated a weak association of repression of TOP2A and TRIM22 with metastasis or death and of overexpression of TERT with subsequent relapse. Most interestingly, histology, the current gold standard used for prediction of risks for relapse and death, could not be verified as potent prognostic factor for neither of them. Hence, realtime RT-PCR analyses can aid in stratification of tumors and prediction of relapse and death risks to intensify therapy for high-risk patients on one hand and to reduce therapy and side-effects in low-risk patients on the other hand. Based on the results of the realtime RT-PCR analyses the expression of several genes was ascertained in primary cell cultures cultivated from native Wilms tumor material. Overexpression of MYCN, TRIM22 and especially HEY2 and EGR1 by viral transduction resulted in high rates of cell death. Unfortunately, the underlying mechanism of death could be determined neither for HEY2 nor for EGR1, though for EGR1 the involvement of apoptosis and senescence could be excluded. In contrast, death in MYCN and especially in TRIM22 overexpressing cells could be attributed to high rates of apoptosis. Furthermore, a large fraction of MYCN cells seem to enter cell senescence and stop to proliferate. These results clearly corroborate the proposed relevance of the investigated genes in the development and/or progression of Wilms tumors. Nevertheless, further experiments in different primary cell cultures of Wilms tumors are necessary to clarify the real potential of these genes. KW - Nephroblastom KW - Real time quantitative PCR KW - LOH 11q KW - LOH 16q KW - lentivirale Transduktion KW - nephroblastoma KW - LOH 11q KW - LOH 16q KW - quantitative RT-PCR KW - lentiviral transduction Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-24891 ER - TY - JOUR A1 - Wittbrodt, Joachim A1 - Lammers, Reiner A1 - Malitschek, Barbara A1 - Ullrich, Axel A1 - Schartl, Manfred T1 - Xmrk receptor tyrosine kinase is activated in Xiphophorus malignant melanoma N2 - Xmrk encodes a putative transmembrane glycoprotein of the tyrosine kinase family and is a melanoma-inducing gene in Xiphophorus. We attempted to investigate the biological function of the putative Xmrk receptor by characterizing its signalling properties. Since a potential Iigand for Xmrk has not yet been identified, it has been difficult to analyse the biochemical properlies and biological function of this cell surface protein. In an approach towards such analyses, the Xmrk extracellular domain was replaced by the closely related Iigand-binding domain sequences of the human epidennal growth factor receptor (HER) and the ligand-induced activity of the chimeric HER-Xmrk proteinwas examined. We show that the Xmrk protein is a functional receptor tyrosine kinase, is highly active in malignant melanoma and displays a constitutive autophosphorylation activity possibly due to an activating mutation in its extracellular or transmembrane domain. In the focus formation assay the HER-Xmrk chimera is a potent transfonning protein equivalent to other tyrosine kinase oncoproteins. KW - Physiologische Chemie KW - chimeric RTKs KW - melanoma KW - RTK KW - Xiphophorus Y1 - 1992 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-61699 ER - TY - JOUR A1 - Wittbrodt, J. A1 - Adam, D. A1 - Malitschek, B. A1 - Maueler, W. A1 - Raulf, F. A1 - Telling, A. A1 - Robertson, M. A1 - Schartl, Manfred T1 - Novel putative receptor tyrosine kinase encoded by the melanoma-inducing Tu locus in Xiphophorus N2 - No abstract available KW - Physiologische Chemie Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-61800 ER - TY - THES A1 - Wistuba, Nicole T1 - Untersuchungen zum Mechanismus des Wassertransportes in Höheren Pflanzen mit Hilfe der Druckmeßsonden- und NMR-Bildgebungstechnik T1 - Investigations on the mechanism of water transport in higher plants by means of the pressure probe- and the NMR-imaging-techniques N2 - Untersuchungen zum Wasserferntransport wurden mit Hife der Druckmeßsonden- und NMR-Bildgebungstechnik durchgeführt. Dabei wurden Experimente zum Einfluß der Schwerkraft auf den Wasserferntransport an einer Liane bei unterschiedlicher Orientierung der Pflanze durchgeführt. Der zweite Teil der Arbeit beschäftigte sich mit der Korrelation von Flußgeschwindigkeiten und Xylemdruck in den Wasserleitungsbahnen gut gewässerter und trockengestreßter Pflanzen. Der dritte Teil befasste sich mit der Wiederbefüllung von kavitierten oder leeren Xylemgefäßen anhand der Auferstehungspflanze Myrothamnus flabellifolia. N2 - Investigations on the water transport were done by means of the pressure probe and NMR-imaging-techniques. Measurements were performed on a liana to determine the influence of gravity on water transport while the plant was placed into different orientations. The second part of this dissertation dealed with the correlation of flow velocity and xylem pressure in well-hydrated and drought-stressed plants. The third part investigated the refilling of cavitated or empty xylem conduits by means of the resurrection plant Myrothamnus flabellifolia. KW - Samenpflanzen KW - Wassertransport KW - Druckmessung KW - NMR-Bildgebung KW - Xylemdruck KW - Xylemdruckmeßsonde KW - NMR-Bildgebung KW - Myrothamnus flabellifolia KW - Epipremnum aureum KW - Wassertransport in Pflanzen KW - xylem pressure KW - xylem pressure probe KW - NMR-imaging KW - Myrothamnus flabellifolia KW - Epipremnum aureum KW - water transport in plants Y1 - 2000 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-2471 ER - TY - JOUR A1 - Wirth, Christine C. A1 - Glushakova, Svetlana A1 - Scheuermayer, Matthias A1 - Repnik, Urska A1 - Garg, Swatl A1 - Schaack, Dominik A1 - Kachman, Marika M. A1 - Weißbach, Tim A1 - Zimmerberg, Joshua A1 - Dandekar, Thomas A1 - Griffiths, Gareth A1 - Chitnis, Chetan E. A1 - Singh, Shallja A1 - Fischer, Rainer A1 - Pradel, Gabriele T1 - Perforin-like protein PPLP2 permeabilizes the red blood cell membrane during egress of Plasmodium falciparum gametocytes JF - Cellular Microbiology N2 - Egress of malaria parasites from the host cell requires the concerted rupture of its enveloping membranes. Hence, we investigated the role of the plasmodial perforin-like protein PPLP2 in the egress of Plasmodium falciparum from erythrocytes. PPLP2 is expressed in blood stage schizonts and mature gametocytes. The protein localizes in vesicular structures, which in activated gametocytes discharge PPLP2 in a calcium-dependent manner. PPLP2 comprises a MACPF domain and recombinant PPLP2 has haemolytic activities towards erythrocytes. PPLP2-deficient [PPLP2(−)] merozoites show normal egress dynamics during the erythrocytic replication cycle, but activated PPLP2(−) gametocytes were unable to leave erythrocytes and stayed trapped within these cells. While the parasitophorous vacuole membrane ruptured normally, the activated PPLP2(−) gametocytes were unable to permeabilize the erythrocyte membrane and to release the erythrocyte cytoplasm. In consequence, transmission of PPLP2(−) parasites to the Anopheles vector was reduced. Pore-forming equinatoxin II rescued both PPLP2(−) gametocyte exflagellation and parasite transmission. The pore sealant Tetronic 90R4, on the other hand, caused trapping of activated wild-type gametocytes within the enveloping erythrocytes, thus mimicking the PPLP2(−) loss-of-function phenotype. We propose that the haemolytic activity of PPLP2 is essential for gametocyte egress due to permeabilization of the erythrocyte membrane and depletion of the erythrocyte cytoplasm. Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-120895 VL - 16 IS - 5 ER - TY - JOUR A1 - Winkler, Christoph A1 - Wittbrodt, Joachim A1 - Lammers, Reiner A1 - Ullrich, Axel A1 - Schartl, Manfred T1 - Ligand-dependent tumor induction in medakafish embryos by a Xmrk receptor tyrosine kinase transgene N2 - Xmrk encodes a subclass 1 receptor tyrosine kinase (RTK) which has been cloned from the melanomainducing locus Tu of the poeciliid fish Xiphophorus. To demonstrate a high oncogenic potential in vivo we transferred the gene into early embryos of the closely related medakafish. Ectopic expression of the Xmrk oncogene under the control of a strong, constitutive promoter (CMVTk) led to the induction of embryonic tumors with high incidence, after short latency periods, and with a specific pattern of affected tissues. We demonstrate ligand-dependent transformation in vivo using a chimeric receptor consisting of the extracellular and transmembrane domains of the human EGF receptor (HER) and the cytoplasmatic domain of Xmrk. Expression of the chimeric receptor alone does not lead to ldnase activation or induction of tumors. Coexpression of the chimera with its corresponding ligand, human transforming growth factor alpha (bTGF(X), however, results in the activation of the chimeric RTK. In injected fish embryos the induction of the neoplastic growth is observed with similar incidence and tissue distribution as in embryos carrying the native Xmrk oncogene suggesting that the ligand as well as factors downstream of tbe RTK are required for tumor formation. In this study we show single-step induction of tumors by ectopic expression of RTKs in vivo substantiating tbe significance of autocrine stimulation in RTK induced tumors in vertebrales. KW - Japankärpfling KW - Ligand KW - Tumor Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-87107 ER - TY - JOUR A1 - Winkler, Christoph A1 - Vielkind, Jürgen R. A1 - Schartl, Manfred T1 - Transient expression of foreign DNA during embryonic and larval development of the medaka fish (Oryzias latipes) N2 - Species of small fish are becoming useful tools for studies on vertebrate development. Wehave investigated the developing embryo of the Japanese medaka for its application as a transient expression system for the in vivo analysis of gene regulation and function. The temporaland spatial expression patterns ofbacterial chloramphenicol acetyltransferase and galactosidase reporter genes injected in supercoiled plasmid form into the cytoplasm of one cell of the two-cell stage embryo was promoter-specific. The transient expression was found to be mosaic within the tissue and organs reflecting the unequal distribution of extrachromosomal foreign DNA and the intensive cell mixing movements that occur in fish embryogenesis. The expression data are consistent with data on DNA fate. Foreign DNA persisted during embryogenesis and was still detectable in some 3- and 9-month-old adult fish; it was found in high molecular weight form as weil as in circular plasmid conformations. The DNA was replicated during early and late embryogenesis. Our data indicate that the developing medaka embryo is a powerful in vivo assay system for studies of gene regulation and function. KW - Physiologische Chemie KW - Medaka - Genetransfer - Transient expression - DNA fate - Fish developmental biology Y1 - 1991 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-61743 ER -