@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}
}
@phdthesis{LuiblneeHermann2014,
  author    = {Luibl [n{\´e}e Hermann], Christiane},
  title     = {The role of the neuropeptides NPF, sNPF, ITP and PDF in the circadian clock of Drosophila melanogaster},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-93796},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2014},
  abstract  = {Organisms have evolved endogenous clocks which allow them to organize their behavior, metabolism and physiology according to the periodically changing environmental conditions on earth. Biological rhythms that are synchronized to daily changes in environment are governed by the so-called circadian clock. Since decades, chronobiologists have been investigating circadian clocks in various model organisms including the fruitfly Drosophila melanogaster, which was used in the present thesis. Anatomically, the circadian clock of the fruitfly consists of about 150 neurons in the lateral and dorsal protocerebrum, which are characterized by their position, morphology and neurochemistry. Some of these neurons had been previously shown to contain either one or several neuropeptides, which are thought to be the main signaling molecules used by the clock. The best investigated of these neuropeptides is the Pigment Dispersing Factor (PDF), which had been shown to constitute a synchronizing signal between clock neurons as well as an output factor of the clock. In collaboration with various coworkers, I investigated the roles of three other clock expressed neuropeptides for the generation of behavioral rhythms and the partly published, partly unpublished data are presented in this thesis. Thereby, I focused on the Neuropeptide F (NPF), short Neuropeptide F (sNPF) and the Ion Transport Peptide (ITP). We show that part of the neuropeptide composition within the clock network seems to be conserved among different Drosophila species. However, the PDF expression pattern in certain neurons varied in species deriving from lower latitudes compared to higher latitudes. Together with findings on the behavioral level provided by other people, these data suggest that different species may have altered certain properties of their clocks - like the neuropeptide expression in certain neurons - in order to adapt their behavior to different habitats. We then investigated locomotor rhythms in Drosophila melanogaster flies, in which neuropeptide circuits were genetically manipulated either by cell ablation or RNA interference (RNAi). We found that none of the investigated neuropeptides seems to be of equal importance for circadian locomotor rhythms as PDF. PDF had been previously shown to be necessary for rhythm maintenance in constant darkness (DD) as well as for the generation of morning (M) activity and for the right phasing of the evening (E) activity in entrained conditions. We now demonstrate that NPF and ITP seem to promote E activity in entrained conditions, but are clearly not the only factors doing so. In addition, ITP seems to reduce nighttime activity. Further, ITP and possibly also sNPF constitute weak period shortening components in DD, thereby opposing the effect of PDF. However, neither NPF or ITP, nor sNPF seem to be necessary in the clock neurons for maintaining rhythmicity in DD. It had been previously suggested that PDF is released rhythmically from the dorsal projection terminals. Now we discovered a rhythm in ITP immunostaining in the dorsal projection terminals of the ITP+ clock neurons in LD, suggesting a rhythm in peptide release also in the case of ITP. Rhythmic release of both ITP and PDF seems to be important to maintain rhythmic behavior in DD, since constantly high levels of PDF and ITP in the dorsal protocerebrum lead to behavioral arrhythmicity. Applying live-imaging techniques we further demonstrate that sNPF acts in an inhibitory way on few clock neurons, including some that are also activated by PDF, suggesting that it acts as signaling molecule within the clock network and has opposing effects to PDF. NPF did only evoke very little inhibitory responses in very few clock neurons, suggesting that it might rather be used as a clock output factor. We were not able to apply the same live-imaging approach for the investigation of the clock neuron responsiveness to ITP, but overexpression of ITP with various driver lines showed that the peptide most likely acts mainly in clock output pathways rather than inter-clock neuron communication. Taking together, I conclude that all investigated peptides contribute to the control of locomotor rhythms in the fruitfly Drosophila melanogaster. However, this control is in most aspects dominated by the actions of PDF and rather only fine-tuned or complemented by the other peptides. I assume that there is a high complexity in spatial and temporal action of the different neuropeptides in order to ensure correct signal processing within the clock network as well as clock output.},
  subject      = {Taufliege},
  language  = {en}
}
@phdthesis{Dusik2015,
  author    = {Dusik, Verena},
  title     = {Immunhistochemische und funktionelle Charakterisierung der Mitogen-aktivierten Proteinkinase p38 in der inneren Uhr von Drosophila melanogaster},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-124636},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2015},
  abstract  = {Circadianes und Stress-System sind zwei physiologische Systeme, die dem Organismus helfen sich an Ver{\"a}nderungen ihrer Umwelt anzupassen. W{\"a}hrend letzteres spontane und schnelle Antworten auf akute, unvorhersehbare Umweltreize liefert, sagt das circadiane System t{\"a}glich wiederkehrende Ereignisse vorher and bereitet den Organismus so vorzeitig auf diese nahende Umweltver{\"a}nderung vor. Dennoch, trotz dieser unterschiedlichen Reaktionsmechanismen agieren beide Systeme nicht komplett autonom. Studien der vergangen Jahre belegen vielmehr eine Interaktion beider Systeme. So postulieren sie zum einem Unterschiede in der Stressantwort in Abh{\"a}ngigkeit von der Tageszeit zu der der Reiz auftritt und weisen zugleich auf eine Zunahme von gest{\"o}rten biologischen Tagesrhythmen, wie zum Beispiel Schlafst{\"o}rungen, in Folge von unkontrollierten oder exzessiven Stress hin. Ebenso liefern k{\"u}rzlich durchgef{\"u}hrte Studien an Vertebraten und Pilzen Hinweise, dass mit p38, eine Stress-aktivierte Kinase, an der Signalweiterleitung zur inneren Uhr beteiligt ist (Hayashi et al., 2003), sogar durch dieses endogene Zeitmesssystem reguliert wird (Vitalini et al., 2007; Lamb et al., 2011) und deuten damit erstmals eine m{\"o}gliche Verbindung zwischen Stress-induzierten und regul{\"a}ren rhythmischen Anpassungen des Organismus an Umweltver{\"a}nderungen an. Molekulare und zellul{\"a}re Mechanismen dieser Verkn{\"u}pfung sind bisher noch nicht bekannt. W{\"a}hrend die Rolle von p38 MAPK bei der Stress- und Immunantwort in Drosophila melanogaster gut charakterisiert ist, wurden Expression und Funktion von p38 in der inneren Uhr hingegen bislang nicht untersucht. Die hier vorliegende Arbeit hatte daher zum Ziel mittels immunhistochemischer, verhaltensphysiologischer und molekularer Methoden eine m{\"o}gliche Rolle der Stress-aktivierten Kinase im circadianen System der Fliege aufzudecken. Antik{\"o}rperf{\"a}rbungen sowie Studien mit Reporterlinien zeigen deutliche F{\"a}rbesignale in den s-LNv, l-LNv und DN1a und erbringen erstmals einen Nachweis f{\"u}r p38 Expression in den Uhrneuronen der Fliege. Ebenso scheint die Aktivit{\"a}t von p38 MAPK in den DN1a uhrgesteuert zu sein. So liegt p38 vermehrt in seiner aktiven Form in der Dunkelphase vor und zeigt, neben seiner circadian regulierten Aktivierung, zus{\"a}tzlich auch eine Inaktivierung durch Licht. 15-Minuten-Lichtpulse in der subjektiven Nacht f{\"u}hren zu einer signifikanten Reduktion von aktivierter, phosphorylierter p38 MAPK in den DN1a von Canton S Wildtypfliegen im Vergleich zu Fliegen ohne Lichtpuls-Behandlung. Aufzeichnungen der Lokomotoraktivit{\"a}t offenbaren zus{\"a}tzlich die Notwendigkeit von p38 MAPK f{\"u}r wildtypisches Timing der Abendaktivit{\"a}t sowie zum Erhalt von 24-Stunden-Verhaltensrhythmen unter konstanten Dauerdunkel-Bedindungen. So zeigen Fliegen mit reduzierten p38 Level in Uhrneuronen einen verz{\"o}gerten Beginn der Abendaktivit{\"a}t und stark verl{\"a}ngerte Freilaufperioden. In {\"U}bereinstimmung mit Effekten auf das Laufverhalten scheint dar{\"u}ber hinaus die Expression einer dominant-negativen Form von p38b in Drosophila's wichtigsten Uhrneuronen eine versp{\"a}tete nukle{\"a}re Translokation von Period zur Folge zu haben. Westernblots legen zus{\"a}tzlich einen Einfluss von p38 auf den Phosphorylierungsgrad von Period nahe und liefern damit einen m{\"o}gliche Erkl{\"a}rung f{\"u}r den versp{\"a}teten Kerneintritt des Uhrproteins. Abschließende St{\"u}tzung der Westernblotergebnisse bringen in vitro Kinasenassays und deuten auf p38 als eine potentielle „Uhrkinase" hin, welche auch in vivo Period an Serin 661 sowie weiteren potentiellen Phosphorylierungsstellen phosphorylieren k{\"o}nnte. Zusammengenommen deuten die Ergebnisse der hier vorliegenden Arbeit eindeutig auf eine bedeutende Rolle von p38, neben dessen Funkion im Stress-System, auch im circadianen System der Fliege hin und offenbaren damit die M{\"o}glichkeit, dass p38 als Schnittstelle zwischen beider Systeme fungiert.},
  subject      = {Taufliege},
  language  = {de}
}