@phdthesis{Haertle2018,
  author    = {Haertle, Larissa},
  title     = {Gestationsdiabetes und fetale Programmierung: Epigenetische Untersuchungen mit verschiedenen Next Generation Sequencing Techniken},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-156465},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2018},
  abstract  = {Eine intrauterine Gestationsdiabetes (GDM) Exposition induziert in den betroffenen Nachkommen eine lebenslang erh{\"o}hte Pr{\"a}disposition f{\"u}r metabolische und komplexe Erkrankungen. Die Krankheitssuszeptibilit{\"a}t wird dabei durch epigenetische Ver{\"a}nderungen vermittelt, die sich {\"u}ber die Regulation der Genaktivit{\"a}t auch auf das Expressionsniveau und den Ph{\"a}notypen auswirken. Um neue Gene zu finden, die eine Rolle in der fetalen Programmierung spielen, wurden in dieser Arbeit genomweite Methylierungsmuster von Nabelschnurbluten (FCBs) aus GDM-Schwangerschaften und Kontrollen miteinander verglichen. Mit Illumina Infinium HumanMethylation 450K Arrays konnten signifikante Gruppenunterschiede f{\"u}r insgesamt 65 CpG-Stellen (52 davon genassoziiert) festgestellt werden, die multiplem Testen standhielten. Mittels Pyrosequenzierung wurden vier dieser Kandidaten-Loci (ATP5A1, MFAP4, PRKCH, SLC17A4), sowie ein Gen aus der Literatur (HIF3A) genauer untersucht und die Effekte erfolgreich validiert. F{\"u}r das zugrundeliegende multivariate Regressionsmodell wurden die potenziellen St{\"o}rfaktoren Gestationsalter, kindliches Geschlecht und m{\"u}tterlicher BMI ber{\"u}cksichtigt. Der GDM-Effekt zeigte sich st{\"a}rker in der insulinbehandelten Subgruppe (I-GDM) als in der di{\"a}tisch behandelten (D GDM) und scheint insgesamt multifaktoriell bedingt zu sein, da viele Gene betroffen waren, jedoch alle mit einer vergleichsweise niedrigen Effekt-Gr{\"o}ße. Zus{\"a}tzlich konnten f{\"u}r den MEG3 Promotor, MEST und PEG3, drei von vier gepr{\"a}gten Genen, die mittels Deep Bisulfite Sequencings (DBS) analysiert wurden, ebenfalls signifikante Methylierungs-unterschiede zwischen der GDM- und Kontroll-Gruppe detektiert werden. Die identifizierten Gene stellen labile Zielregionen f{\"u}r die GDM-induzierte intrauterine Programmierung dar und k{\"o}nnen zuk{\"u}nftig n{\"u}tzliche Biomarker f{\"u}r Krankheitsdiagnosen und Prognosen sein. Mittels DBS k{\"o}nnen dar{\"u}ber hinaus Einzelmolek{\"u}l-Analysen durchgef{\"u}hrt werden, f{\"u}r die in differentiell methylierten Regionen (DMRs) anhand eines informativen SNPs die parentale Allel-Herkunft bestimmt und bei der Berechnung von Epimutationsraten einbezogen werden kann. Epimutationen wurde als solche gewertet, wenn sie ein > 50 \% abnormal (de)methyliertes Methylierungsprofil aufwiesen. Die DBS-Daten wurden mit zwei verschiedenen Sequenzierplattformen generiert (Roche GS Junior und Illumina MiSeq). F{\"u}r Zweitere wurde ein eigenes, unabh{\"a}ngiges Library-Pr{\"a}parations-Protokoll entwickelt. In Nabelschnurblut, adultem Blut und Viszeralfett wurden f{\"u}r die paternal exprimierte MEST Promotor DMR und die maternal exprimierte MEG3 intergenic (IG) DMR hohe Epimutationsraten f{\"u}r das jeweils unmethylierte Allel detektiert. Die gepr{\"a}gten (methylierten) Allele wiesen dagegen nur niedrige Epimutationsraten auf. Da MEST und MEG3 invers gepr{\"a}gte Gene sind, war die Hypermethylierung des nicht gepr{\"a}gten Allels (HNA) demnach unabh{\"a}ngig von der parentalen Allel-Herkunft. Die HNA scheint außerdem erst nach der Fertilisation aufzutreten, da in Spermien nur sehr wenige Epimutationen gefunden wurden. F{\"u}r die sekund{\"a}re MEG3 Promotor DMR (deren Pr{\"a}gung von der prim{\"a}ren MEG3 IG-DMR reguliert wird) wurde ein deutlich schw{\"a}cherer, wenngleich signifikanter HNA-Effekt im FCB gemessen, f{\"u}r die paternal exprimierte PEG3 Promotor DMR konnte dagegen kein signifikanter Unterschied zwischen den beiden parentalen Epimutationsraten festgestellt werden. Der HNA-Effekt f{\"u}r die MEST DMR, MEG3 IG-DMR und MEG3 Promotor DMR war weder mit GDM noch mit Adipositas assoziiert und zeigte allgemein eine große interindividuelle Varianz. Die Aufrechterhaltung differenzieller Methylierungsmuster in Imprinting Kontrollregionen (ICRs) scheint in manchen Entwicklungs-Zeitspannen von großer Bedeutung und damit streng kontrolliert zu sein, sp{\"a}ter jedoch redundant zu werden, was sich in der Anreicherung von stochastischen sowie umweltinduzierten Fehlern auf dem nicht gepr{\"a}gten Allel {\"a}ußern kann. HNA-suszeptible gepr{\"a}gte Gene {\"a}hneln in mancherlei Hinsicht metastabilen Epiallelen. Diese Studie zeigt, dass sowohl stochastische Faktoren als auch Umweltstimuli w{\"a}hrend der fr{\"u}hen embryonalen Entwicklung u.a. {\"u}ber HNA-Effekte gepr{\"a}gte Gen-Netzwerke programmieren, die in Wachstumsprozesse involviert sind. Um tiefere Einblicke in allelspezifische Pr{\"a}gungsprofile zu erhalten, w{\"a}ren umfangreiche DBS HNA-L{\"a}ngsschnittstudien aller 50-100 human gepr{\"a}gten Gene in unterschiedlichen Gewebetypen und Differenzierungsstadien w{\"u}nschenswert.  },
  subject      = {Schwangerschaftsdiabetes},
  language  = {de}
}
@phdthesis{Maierhofer2018,
  author    = {Maierhofer, Anna},
  title     = {Altersassoziierte und strahleninduzierte Ver{\"a}nderungen des genomweiten DNA-Methylierungs-Profils},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-174134},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2018},
  abstract  = {Der Prozess des Alterns ist ein komplexer multifaktorieller Vorgang, der durch eine sukzessive Verschlechterung der physiologischen Funktionen charakterisiert ist. Ein hohes Alter ist der Hauptrisikofaktor f{\"u}r die meisten Krankheiten, einschließlich Krebs und Herz-Kreislauf-Erkrankungen. Das Verst{\"a}ndnis der epigenetischen Mechanismen, die in den Prozess des Alterns involviert sind, k{\"o}nnte zur Entwicklung pharmakologischer Interventionen beitragen, die nicht nur die Lebenserwartung erh{\"o}hen, sondern auch den Beginn des altersassoziierten funktionellen Abbaus verz{\"o}gern k{\"o}nnten. Durch die Langzeit-Kultivierung prim{\"a}rer humaner Fibroblasten wurde ein in vitro Modell f{\"u}r das Altern etabliert, das die Identifizierung altersassoziierter DNA-Methylierungs-Ver{\"a}nderungen erm{\"o}glichte. Die in vitro Alterung konnte mit einer globalen Hypomethylierung und einer erh{\"o}hten DNA-Methylierung der ribosomalen DNA assoziiert werden. Dar{\"u}ber hinaus konnten DNA-Methylierungs-Ver{\"a}nderungen in Genen und Signalwegen, die f{\"u}r das Altern relevant sind, und ein erh{\"o}htes epigenetisches Alter nachgewiesen werden. Das in vitro Modell f{\"u}r das Altern wurde verwendet, um neben den direkten Effekten ionisierender Strahlung auf die DNA-Methylierung auch deren Langzeit-Effekte zu untersuchen. Die Strahlentherapie ist ein entscheidendes Element der Krebstherapie, hat aber auch negative Auswirkungen und kann unter anderem das Risiko f{\"u}r die Entwicklung eines Zweittumors erh{\"o}hen. Bei externer Bestrahlung wird neben dem Tumor auch gesundes Gewebe ionisierender Strahlung ausgesetzt. Daher ist es wichtig zu untersuchen, wie Zellen mit intakten DNA-Reparatur-Mechanismen und funktionierenden Zellzyklus-Checkpoints durch diese beeinflusst werden. In der fr{\"u}hen Phase der DNA-Schadensantwort auf Bestrahlung wurden in normalen Zellen keine wesentlichen DNA-Methylierungs-Ver{\"a}nderungen beobachtet. Mehrere Populations-Verdoppelungen nach Strahlenexposition konnten dagegen eine globale Hypomethylierung, eine erh{\"o}hte DNA-Methylierung der ribosomalen DNA und ein erh{\"o}htes epigenetisches Alter detektiert werden. Des Weiteren zeigten Gene und Signalwege, die mit Krebs in Verbindung gebracht wurden, Ver{\"a}nderungen in der DNA-Methylierung. Als Langzeit-Effekte ionisierender Strahlung traten somit die mit der in vitro Alterung assoziierten DNA-Methylierungs-Ver{\"a}nderungen verst{\"a}rkt auf und ein epigenetisches Muster, das stark an das DNA-Methylierungs-Profil von Tumorzellen erinnert, entstand. Man geht davon aus, dass Ver{\"a}nderungen der DNA-Methylierung eine aktive Rolle in der Entwicklung eines Tumors spielen. Die durch ionisierende Strahlung induzierten DNA-Methylierungs-Ver{\"a}nderungen in normalen Zellen k{\"o}nnten demnach in die Krebsentstehung nach Strahlenexposition involviert sein und zu dem sekund{\"a}ren Krebsrisiko nach Strahlentherapie beitragen. Es ist bekannt, dass Patienten unterschiedlich auf therapeutische Bestrahlung reagieren. Die Ergebnisse dieser Arbeit weisen darauf hin, dass die individuelle Sensitivit{\"a}t gegen{\"u}ber ionisierender Strahlung auch auf epigenetischer Ebene beobachtet werden kann. In einem zweiten Projekt wurden Gesamtblutproben von Patienten mit Werner-Syndrom, einer segmental progeroiden Erkrankung, und gesunden Kontrollen analysiert, um mit dem vorzeitigen Altern in Verbindung stehende DNA-Methylierungs-Ver{\"a}nderungen zu identifizieren. Werner-Syndrom konnte nicht mit einer globalen Hypomethylierung, jedoch mit einer erh{\"o}hten DNA-Methylierung der ribosomalen DNA und einem erh{\"o}hten epigenetischen Alter assoziiert werden. Das vorzeitige Altern geht demzufolge mit spezifischen epigenetischen Ver{\"a}nderungen einher, die eine Beschleunigung der mit dem normalen Altern auftretenden DNA-Methylierungs-Ver{\"a}nderungen darstellen. Im Rahmen dieser Arbeit konnte die Bedeutung epigenetischer Mechanismen im Prozess des Alterns hervorgehoben werden und gezeigt werden, dass sowohl exogene Faktoren, wie ionisierende Strahlung, als auch endogene Faktoren, wie das in Werner-Syndrom-Patienten mutiert vorliegende WRN-Gen, altersassoziierte DNA-Methylierungs-Ver{\"a}nderungen beeinflussen k{\"o}nnen.},
  subject      = {Methylierung},
  language  = {de}
}
@phdthesis{Mildner2018,
  author    = {Mildner, Stephanie},
  title     = {Temporal organization in \(Camponotus\) \(ants\): endogenous clocks and zeitgebers responsible for synchronization of task-related circadian rhythms in foragers and nurses},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-149382},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2018},
  abstract  = {The rotation of the earth around its axis causes recurring and predictable changes in the environment. To anticipate those changes and adapt their physiology and behavior accordingly, most organisms possess an endogenous clock. The presence of such a clock has been demonstrated for several ant species including Camponotus ants, but its involvement in the scheduling of daily activities within and outside the ant nest is fairly unknown. Timing of individual behaviors and synchronization among individuals is needed to generate a coordinated collective response and to maintain colony function. The aim of this thesis was to investigate the presence of a circadian clock in different worker castes, and to determine the daily timing of their behavioral tasks within the colonies of two nectar-collecting Camponotus species. In chapter I, I describe the general temporal organization of work throughout the worker life in the species Camponotus rufipes. Continuous tracking of behavioral activity of individually- marked workers for up to 11 weeks in subcolonies revealed an age-dependent division of labor between interior and exterior workers. After eclosion, the fairly immobile young ants were frequently nurtured by older nurses, yet they started nursing the brood themselves within the first 48 hours of their life. Only 60\% of workers switched to foraging at an age range of one to two weeks, likely because of the reduced needs within the small scale of the subcolonies. Not only the transition rates varied between subcolonies, but also the time courses of the task sequences between workers did, emphasizing the timed allocation of workers to different tasks in response to colony needs. Most of the observed foragers were present outside the nest only during the night, indicating a distinct timing of this behavioral activity on a daily level as well. As food availability, humidity and temperature levels were kept constant throughout the day, the preference for nocturnal activity seems to be endogenous and characteristic for C. rufipes. The subsequent monitoring of locomotor activity of workers taken from the subcolonies revealed the presence of a functional endogenous clock already in one-day old ants. As some nurses displayed activity rhythms in phase with the foraging rhythm, a synchronization of these in-nest workers by social interactions with exterior workers can be hypothesized. Do both castes use their endogenous clock to schedule their daily activities within the colony? In chapter II, I analyzed behavioral activity of C. rufipes foragers and nurses within the social context continuously for 24 hours. As time-restricted access to food sources may be one factor affecting daily activities of ants under natural conditions, I confronted subcolonies with either daily pulses of food availability or ad libitum feeding. Under nighttime and ad libitum feeding, behavioral activity of foragers outside the nest was predominantly nocturnal, confirming the results from the simple counting of exterior workers done in chapter I. Foragers switched to diurnality during daytime feeding, demonstrating the flexible and adaptive timing of a daily behavior. Because they synchronized their activity with the short times of food availability, these workers showed high levels of inactivity. Nurses, in contrast, were active all around the clock independent of the feeding regime, spending their active time largely with feeding and licking the brood. After the feeding pulses, however, a short bout of activity was observed in nurses. During this time period, both castes increasingly interacted via trophallaxis within the nest. With this form of social zeitgeber, exterior workers were able to entrain in-nest workers, a phenomenon observed already in chapter I. Under the subsequent monitoring of locomotor activity under LD conditions the rhythmic workers of both castes were uniformly nocturnal independent of the feeding regime. This endogenous activity pattern displayed by both worker castes in isolation was modified in the social context in adaption to task demands. Chapter III focuses on the potential factors causing the observed plasticity of daily rhythms in the social context in the ant C. rufipes. As presence of brood and conspecifics are likely indicators of the social context, I tested the effect of these factors on the endogenous rhythms of otherwise isolated individuals. Even in foragers, the contact to brood triggered an arrhythmic activity pattern resembling the arrhythmic behavioral activity pattern seen in nurses within the social context. As indicated in chapter I and II, social interaction could be one crucial factor for the synchronization of in nest activities. When separate groups were entrained to phase-shifted light-dark-cycles and monitored afterwards under constant conditions in pairwise contact through a mesh partitioning, both individuals shifted parts of their activity towards the activity period of the conspecific. Both social cues modulated the endogenous rhythms of workers and contribute to the context dependent plasticity in ant colonies. Although most nursing activities are executed arrhythmically throughout the day (chapter II), previous studies reported rhythmic translocation events of the brood in Camponotus nurses. As this behavior favors brood development, the timing of the translocations within the dark nest seems to be crucial. In chapter IV, I tracked translocation activity of all nurses within subcolonies of C. mus. Under the confirmed synchronized conditions of a LD-cycle, the daily pattern of brood relocation was based on the rhythmic, alternating activity of subpopulations with preferred translocation direction either to the warm or to the cold part of the temperature gradient at certain times of the day. Although the social interaction after pulse feeding had noticeable effects on the in-nest activity in C. rufipes (chapter I and II), it was not sufficient to synchronize the brood translocation rhythm of C. mus under constant darkness (e.g. when other zeitgebers were absent). The free-running translocation activity in some nurses demonstrated nevertheless the involvement of an endogenous clock in this behavior, which could be entrained under natural conditions by other potential non-photic zeitgebers like temperature and humidity cycles. Daily cycling of temperature and humidity could not only be relevant for in-nest activities, but also for the foraging activity outside the nest. Chapter V focuses on the monitoring of field foraging rhythms in the sympatric species C. mus and C. rufipes in relation to abiotic factors. Although both species had comparable critical thermal limits in the laboratory, foragers in C. mus were strictly diurnal and therefore foraged under higher temperatures than the predominant nocturnal foragers in C. rufipes. Marking experiments in C. rufipes colonies with higher levels of diurnal activity revealed the presence of temporally specialized forager subpopulations. These results suggest the presence of temporal niches not only between the two Camponotus species, but as well between workers within colonies of the same species. In conclusion, the temporal organization in colonies of Camponotus ants involves not only the scheduling of tasks performed throughout the worker life, but also the precise timing of daily activities. The necessary endogenous clock is already functioning in all workers after eclosion. Whereas the light-dark cycle and food availability seem to be the prominent zeitgebers for foragers, nurses may rely more on non-photic zeitgeber like social interaction, temperature and humidity cycles.},
  subject      = {circadian clocks},
  language  = {en}
}
@phdthesis{Kay2018,
  author    = {Kay, Janina},
  title     = {The circadian clock of the carpenter ant \(Camponotus\) \(floridanus\)},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-158061},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2018},
  abstract  = {Due to the earth´s rotation around itself and the sun, rhythmic daily and seasonal changes in illumination, temperature and many other environmental factors occur. Adaptation to these environmental rhythms presents a considerable advantage to survival. Thus, almost all living beings have developed a mechanism to time their behavior in accordance. This mechanism is the endogenous clock. If it fulfills the criteria of (1) entraining to zeitgebers (2) free-running behavior with a period of ~ 24 hours (3) temperature compensation, it is also referred to as "circadian clock". Well-timed behavior is crucial for eusocial insects, which divide their tasks among different behavioral castes and need to respond to changes in the environment quickly and in an orchestrated fashion. Circadian rhythms have thus been studied and observed in many eusocial species, from ants to bees. The underlying mechanism of this clock is a molecular feedback loop that generates rhythmic changes in gene expression and protein levels with a phase length of approximately 24 hours. The properties of this feedback loop are well characterized in many insects, from the fruit fly Drosophila melanogaster, to the honeybee Apis mellifera. Though the basic principles and components of this loop are seem similar at first glance, there are important differences between the Drosophila feedback loop and that of hymenopteran insects, whose loop resembles the mammalian clock loop. The protein PERIOD (PER) is thought to be a part of the negative limb of the hymenopteran clock, partnering with CRYPTOCHROME (CRY). The anatomical location of the clock-related neurons and the PDF-network (a putative in- and output mediator of the clock) is also well characterized in Drosophila, the eusocial honeybee as well as the nocturnal cockroach Leucophea maderae. The circadian behavior, anatomy of the clock and its molecular underpinnings were studied in the carpenter ant Camponotus floridanus, a eusocial insect Locomotor activity recordings in social isolation proved that the majority of ants could entrain to different LD cycles, free-ran in constant darkness and had a temperature-compensated clock with a period slightly shorter than 24 hours. Most individuals proved to be nocturnal, but different types of activity like diurnality, crepuscularity, rhythmic activity during both phases of the LD, or arrhythmicity were also observed. The LD cycle had a slight influence on the distribution of these activities among individuals, with more diurnal ants at shorter light phases. The PDF-network of C. floridanus was revealed with the anti-PDH antibody, and partly resembled that of other eusocial or nocturnal insects. A comparison of minor and major worker brains, only revealed slight differences in the number of somata and fibers crossing the posterior midline. All in all, most PDF-structures that are conserved in other insects where found, with numerous fibers in the optic lobes, a putative accessory medulla, somata located near the proximal medulla and many fibers in the protocerebrum. A putative connection between the mushroom bodies, the optic lobes and the antennal lobes was found, indicating an influence of the clock on olfactory learning. Lastly, the location and intensity of PER-positive cell bodies at different times of a 24 hour day was established with an antibody raised against Apis mellifera PER. Four distinct clusters, which resemble those found in A. mellifera, were detected. The clusters could be grouped in dorsal and lateral neurons, and the PER-levels cycled in all examined clusters with peaks around lights on and lowest levels after lights off. In summary, first data on circadian behavior and the anatomy and workings of the clock of C. floridanus was obtained. Firstly, it´s behavior fulfills all criteria for the presence of a circadian clock. Secondly, the PDF-network is very similar to those of other insects. Lastly, the location of the PER cell bodies seems conserved among hymenoptera. Cycling of PER levels within 24 hours confirms the suspicion of its role in the circadian feedback loop.},
  subject      = {Chronobiologie},
  language  = {en}
}