TY - JOUR A1 - Hofstetter, Julia A1 - Ogunleye, Ayoola A1 - Kutschke, André A1 - Buchholz, Lisa Marie A1 - Wolf, Elmar A1 - Raabe, Thomas A1 - Gallant, Peter T1 - Spt5 interacts genetically with Myc and is limiting for brain tumor growth in Drosophila JF - Life Science Alliance N2 - The transcription factor SPT5 physically interacts with MYC oncoproteins and is essential for efficient transcriptional activation of MYC targets in cultured cells. Here, we use Drosophila to address the relevance of this interaction in a living organism. Spt5 displays moderate synergy with Myc in fast proliferating young imaginal disc cells. During later development, Spt5-knockdown has no detectable consequences on its own, but strongly enhances eye defects caused by Myc overexpression. Similarly, Spt5-knockdown in larval type 2 neuroblasts has only mild effects on brain development and survival of control flies, but dramatically shrinks the volumes of experimentally induced neuroblast tumors and significantly extends the lifespan of tumor-bearing animals. This beneficial effect is still observed when Spt5 is knocked down systemically and after tumor initiation, highlighting SPT5 as a potential drug target in human oncology. KW - Drosophila KW - transcription factor SPT5 KW - Myc KW - brain tumor KW - tumor growth Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-350197 SN - 2575-1077 VL - 7 IS - 1 ER - TY - JOUR A1 - Pütz, Stephanie M. A1 - Kram, Jette A1 - Rauh, Elisa A1 - Kaiser, Sophie A1 - Toews, Romy A1 - Lueningschroer-Wang, Yi A1 - Rieger, Dirk A1 - Raabe, Thomas T1 - Loss of p21-activated kinase Mbt/PAK4 causes Parkinson-like symptoms in Drosophila JF - Disease Models & Mechanisms N2 - Parkinson's disease (PD) provokes bradykinesia, resting tremor, rigidity and postural instability, and also non-motor symptoms such as depression, anxiety, sleep and cognitive impairments. Similar phenotypes can be induced in Drosophila melanogaster through modification of PD-relevant genes or the administration of PD inducing toxins. Recent studies correlated deregulation of human p21-activated kinase 4 (PAK4) with PD, leaving open the question of a causative relationship of mutations in this gene for manifestation of PD symptoms. To determine whether flies lacking the PAK4 homolog Mushroom bodies tiny (Mbt) show PD-like phenotypes, we tested for a variety of PD criteria. Here, we demonstrate that mbt mutant flies show PD-like phenotypes including age-dependent movement deficits, reduced life expectancy and fragmented sleep. They also react to a stressful situation with higher immobility, indicating an influence of Mbt on emotional behavior. Loss of Mbt function has a negative effect on the number of dopaminergic protocerebral anterior medial (PAM) neurons, most likely caused by a proliferation defect of neural progenitors. The age-dependent movement deficits are not accompanied by a corresponding further loss of PAM neurons. Previous studies highlighted the importance of a small PAM subgroup for age-dependent PD motor impairments. We show that impaired motor skills are caused by a lack of Mbt in this PAM subgroup. In addition, a broader re-expression of Mbt in PAM neurons improves life expectancy. Conversely, selective Mbt knockout in the same cells shortens lifespan. We conclude that mutations in Mbt/PAK4 can play a causative role in the development of PD phenotypes. KW - Sleep fragmentation KW - Life expectancy KW - Emotional behavior KW - Dopaminergic PAM cluster neurons KW - Drosophila KW - Parkinson's disease KW - Mbt KW - PAK4 KW - Negative geotaxis Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-259222 VL - 14 IS - 6 ER - TY - JOUR A1 - Senthilan, Pingkalai R. A1 - Helfrich-Förster, Charlotte T1 - Rhodopsin 7-The unusual Rhodopsin in Drosophila JF - PeerJ N2 - Rhodopsins are the major photopigments in the fruit fly Drosophila melanogaster. Drosophila express six well-characterized Rhodopsins (Rh1–Rh6) with distinct absorption maxima and expression pattern. In 2000, when the Drosophila genome was published, a novel Rhodopsin gene was discovered: Rhodopsin 7 (Rh7). Rh7 is highly conserved among the Drosophila genus and is also found in other arthropods. Phylogenetic trees based on protein sequences suggest that the seven Drosophila Rhodopsins cluster in three different groups. While Rh1, Rh2 and Rh6 form a “vertebrate-melanopsin-type”–cluster, and Rh3, Rh4 and Rh5 form an “insect-type”-Rhodopsin cluster, Rh7 seem to form its own cluster. Although Rh7 has nearly all important features of a functional Rhodopsin, it differs from other Rhodopsins in its genomic and structural properties, suggesting it might have an overall different role than other known Rhodopsins. KW - vision KW - Drosophila KW - Opsins KW - Rhodopsins KW - phototransduction Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-177998 VL - 4 ER - TY - THES A1 - Dannhäuser, Sven T1 - Function of the Drosophila adhesion-GPCR Latrophilin/CIRL in nociception and neuropathy T1 - Funktionelle Rolle des Drosophila aGPCR Latrophilin/CIRL in Nozizeption und Neuropathie N2 - Touch sensation is the ability to perceive mechanical cues which is required for essential behaviors. These encompass the avoidance of tissue damage, environmental perception, and social interaction but also proprioception and hearing. Therefore research on receptors that convert mechanical stimuli into electrical signals in sensory neurons remains a topical research focus. However, the underlying molecular mechanisms for mechano-metabotropic signal transduction are largely unknown, despite the vital role of mechanosensation in all corners of physiology. Being a large family with over 30 mammalian members, adhesion-type G protein-coupled receptors (aGPCRs) operate in a vast range of physiological processes. Correspondingly, diverse human diseases, such as developmental disorders, defects of the nervous system, allergies and cancer are associated with these receptor family. Several aGPCRs have recently been linked to mechanosensitive functions suggesting, that processing of mechanical stimuli may be a common feature of this receptor family – not only in classical mechanosensory structures. This project employed Drosophila melanogaster as the candidate to analyze the aGPCR Latrophilin/dCIRL function in mechanical nociception in vivo. To this end, we focused on larval sensory neurons and investigated molecular mechanisms of dCIRL activity using noxious mechanical stimuli in combination with optogenetic tools to manipulate second messenger pathways. In addition, we made use of a neuropathy model to test for an involvement of aGPCR signaling in the malfunctioning peripheral nervous system. To do so, this study investigated and characterized nocifensive behavior in dCirl null mutants (dCirlKO) and employed genetically targeted RNA-interference (RNAi) to cell-specifically manipulate nociceptive function. The results revealed that dCirl is transcribed in type II class IV peripheral sensory neurons – a cell type that is structurally similar to mammalian nociceptors and detects different nociceptive sensory modalities. Furthermore, dCirlKO larvae showed increased nocifensive behavior which can be rescued in cell specific reexpression experiments. Expression of bPAC (bacterial photoactivatable adenylate cyclase) in these nociceptive neurons enabled us to investigate an intracellular signaling cascade of dCIRL function provoked by light-induced elevation of cAMP. Here, the findings demonstrated that dCIRL operates as a down-regulator of nocifensive behavior by modulating nociceptive neurons. Given the clinical relevance of this results, dCirl function was tested in a chemically induced neuropathy model where it was shown that cell specific overexpression of dCirl rescued nocifensive behavior but not nociceptor morphology. N2 - Der Tastsinn ist die Fähigkeit, mechanische Reize wahrzunehmen, die für essentielle Verhaltensweisen notwendig sind. Dazu gehören die Vermeidung von Gewebsschädigungen, die Wahrnehmung der Umwelt und soziale Interaktion, aber auch die Propriozeption und das Hören. Daher bleibt die Forschung an Rezeptoren, die mechanische Reize in sensorischen Neuronen in elektrische Signale umwandeln, ein aktueller Forschungsschwerpunk. Die zugrundeliegenden molekularen Mechanismen für die mechanometabotrope Signalübertragung sind trotz der wesentlichen Rolle des Tastsinns in allen Bereichen der Physiologie weitgehend unbekannt. Adhäsions G-Protein gekoppelte Rezeptoren (aGPCRs), eine große Molekülfamilie mit über 30 Vertretern im Menschen, sind an einer Vielzahl von physiologischen Prozessen beteiligt. Demzufolge wird ein Zusammenhang zwischen diesen Rezeptoren und verschiedenen Erkrankungen des Menschen, wie z. B. Entwicklungsstörungen, Defekte des Nervensystems, Allergien und Krebs, angenommen. Mehrere aGPCRs wurden kürzlich mit mechanosensitiven Funktionen in Verbindung gebracht, was darauf hindeutet, dass die Verarbeitung mechanischer Reize ein gemeinsames Merkmal dieser Rezeptorfamilie ist – nicht nur in klassischen mechanosensorischen Strukturen. In diesem Projekt wurde Drosophila melanogaster verwendet, um die Funktion des aGPCR-Latrophilin/dCIRL in der mechanischen Nozizeption in vivo zu analysieren. Zu diesem Zweck konzentriert sich diese Arbeit auf mechano-sensorische Neurone (Typ II Klasse IV) der Fruchtfliegenlarve, um die molekularen Mechanismen der dCIRL-Aktivität zu untersuchen. Hierzu wurden noxische mechanische Reize in Kombination mit optogenetischen Werkzeugen, zur Manipulation der Second-Messenger-Signalübertragung, herangezogen. Zusätzlich wurde ein Neuropathie-Modell etabliert, um eine Beteiligung des aGPCRs dCIRL am beeinträchtigten peripheren Nervensystem zu testen. Zu diesem Zweck untersucht und charakterisiert diese Studie das nozizeptive Verhalten in dCirl-Nullmutanten (dCirlKO) und die RNA-Interferenz (RNAi) Methode, um zellspezifische Manipulationen auszuführen. Die Ergebnisse zeigen, dass dCirl in spezifischen peripheren sensorischen Neuronen (C4da) transkribiert wird - ein Zelltyp, der Nozizeptoren in Säugern strukturell ähnlich ist und verschiedene nozizeptive sensorische Modalitäten vermittelt. Darüber hinaus zeigen dCirlKO-Larven ein erhöhtes nozizeptives Verhalten, welches mittels zellspezifischer Reexpression gerettet werden kann. Die Expression von bPAC (bakterielle photoaktivierbare Adenylatcyclase) in diesen nozizeptiven Neuronen ermöglichte es, intrazelluläre Signalkaskaden von CIRL zu untersuchen, welche durch lichtinduzierte Erhöhung von cAMP angeregt werden. Dieser Versuch zeigt, dass dCIRL durch die Modulation nozizeptiver Neuronen eine Herabregulation des nozizeptiven Verhaltens bewirkt. Angesichts der klinischen Relevanz dieses Ergebnisses wurde die dCirl-Funktion in einem chemisch induzierten Neuropathie-Modell getestet. Dabei stellte sich heraus, dass zellspezifische Überexpression von dCirl eine ausgeprägte Hyperalgesie reduziert, morphologische Schädigungen hingegen nicht gerettet werden konnten. KW - Drosophila KW - Fluoreszenzmikroskopie KW - Nozizeption KW - Neuropathie KW - nociception KW - neuropathy KW - adhesion-GPCR KW - aGPCR KW - dCIRL KW - Latrophilin Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-201580 ER - TY - JOUR A1 - Cate, Marie-Sophie A1 - Gajendra, Sangeetha A1 - Alsbury, Samantha A1 - Raabe, Thomas A1 - Tear, Guy A1 - Mitchell, Kevin J. T1 - Mushroom body defect is required in parallel to Netrin for midline axon guidance in Drosophila JF - Development N2 - The outgrowth of many neurons within the central nervous system is initially directed towards or away from the cells lying at the midline. Recent genetic evidence suggests that a simple model of differential sensitivity to the conserved Netrin attractants and Slit repellents is insufficient to explain the guidance of all axons at the midline. In the Drosophila embryonic ventral nerve cord, many axons still cross the midline in the absence of the Netrin genes (NetA and NetB) or their receptor frazzled. Here we show that mutation of mushroom body defect (mud) dramatically enhances the phenotype of Netrin or frazzled mutants, resulting in many more axons failing to cross the midline, although mutations in mud alone have little effect. This suggests that mud, which encodes a microtubule-binding coiled-coil protein homologous to NuMA and LIN-5, is an essential component of a Netrin-independent pathway that acts in parallel to promote midline crossing. We demonstrate that this novel role of Mud in axon guidance is independent of its previously described role in neural precursor development. These studies identify a parallel pathway controlling midline guidance in Drosophila and highlight a novel role for Mud potentially acting downstream of Frizzled to aid axon guidance. KW - Drosophila KW - Axon guidance KW - Midline KW - Mud KW - NuMA KW - LIN-5 KW - Netrin Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-189770 VL - 143 IS - 6 ER - TY - THES A1 - Horn [née Bunz], Melanie T1 - The impact of Drosophila melanogaster`s endogenous clock on fitness: Influence of day length, humidity and food composition T1 - Auswirkungen von Drosophila melanogaster`s Innerer Uhr auf die Fitness: Einfluss von Tageslänge, Luftfeuchtigkeit und Ernährung N2 - We are living in a system that underlies permanent environmental changes due to the rotation of our planet. These changes are rhythmic with the most prominent one having a period of about 24 hours, but also shorter and longer rhythms characterize our environment. To cope with the ever-changing environmental conditions, it is thought to be beneficial if an organism can track and anticipate these changes. The so called endogenous clocks enable this and might provide a fitness advantage. To investigate and unravel the mechanism of endogenous clocks Chronobiologists have used different model organisms. In this thesis Drosophila melanogaster was used as model organism with its about 150 clock neurons representing the main endogenous clock of the fly in the central brain. The molecular mechanisms and the interlocked feedback loops with the main circadian key players like period, timeless, clock or cycle are under investigation since the 1970s and are characterized quite well so far. But the impact of a functional endogenous clock in combination with diverse factors and the resulting fitness advantages were analysed in only a few studies and remains for the most part unknown. Therefore the aim of this thesis was to unravel the impact of Drosophila melanogaster`s endogenous clock on the fitness of the fly. To achieve this goal different factors – like day length, humidity and food composition – were analyzed in wild type CS and three different period mutants, namely perL, perS and per01, that carry a point mutation altering or abolishing the free-running period of the fruit fly as well as a second arrhythmic strain, clkAR. In competition assay experiments wild type and clock mutant flies competed for up to 63 generations under a normal 24 hour rhythm with 12 hours light/day and 12 hours darkness/night (LD12:12) or T-cycles with 19 or 29 hours, according to the mutants free-running period, or constant light (LL) in case of the arrhythmic mutant as well as under natural-like outdoor conditions in two consecutive years. Overall the wild type CS strain was outcompeting the clock mutant strains independent of the environmental conditions. As the perL fly strain elongated their free-running period, the competition experiments were repeated with naturally cantonized new fly strains. With these experiments it could be shown that the genetic background of the fly strains – which are kept for decades in the lab, with backcrosses every few years – is very important and influences the fitness of flies. But also the day length impacts the fitness of the flies, enabling them to persist in higher percentage in a population under competition. Further factors that might influence the survival in a competing population were investigated, like e.g. mating preferences and locomotor activity of homo- and heterozygous females or sperm number of males transferred per mating. But these factors can still not explain the results in total and play no or only minor roles and show the complexity of the whole system with still unknown characteristics. Furthermore populations of flies were recorded to see if the flies exhibit a common locomotor activity pattern or not and indeed a population activity pattern could be recorded for the first time and social contact as a Zeitgeber could be verified for Drosophila melanogaster. In addition humidity and its impact on the flies´ fitness as well as a potential Zeitgeber was examined in this thesis. The flies experienced different relative humidities for eclosion and wing expansion and humidity cycle phase shifting experiments were performed to address these two different questions of fitness impact and potential Zeitgeber. The fruit fly usually ecloses in the morning hours when the relative humidity is quite high and the general assumption was that they do so to prevent desiccation. The results of this thesis were quite clear and demonstrate that the relative humidity has no great effect on the fitness of the flies according to successful eclosion or wing expansion and that temperature might be the more important factor. In the humidity cycle phase shifting experiments it could be revealed that relative humidity cannot act as a Zeitgeber for Drosophila melanogaster, but it influences and therefore masks the activity of flies by allowing or surpressing activity at specific relative humidity values. As final experiments the lifespan of wild type and clock mutant flies was investigated under different day length and with different food qualities to unravel the impact of these factors on the fitness and therefore survival of the flies on the long run. As expected the flies with nutrient-poor minimum medium died earlier than on the nutrient-rich maximum medium, but a small effect of day length could also be seen with flies living slightly longer when they experience environmental day length conditions resembling their free-running period. The experiments also showed a fitness advantage of the wild type fly strain against the clock mutant strains for long term, but not short term (about the first 2-3 weeks). As a conclusion it can be said that genetic variation is important to be able to adapt to changing environmental conditions and to optimize fitness and therefore survival. Having a functional endogenous clock with a free-running period of about 24 hours provides fitness advantages for the fruit fly, at least under competition. The whole system is very complex and many factors – known and unknown ones – play a role in this system by interacting on different levels, e.g. physiology, metabolism and/or behavior. N2 - Wir leben in einem System, welches durch die Erdrotation permanenten Veränderungen der Umwelt unterliegt. Diese Veränderungen sind rhythmischer Natur, wobei die wichtigste Veränderung einen Rhythmus von circa 24 Stunden aufweist. Aber auch kürzere und längere Rhythmen charakterisieren unsere Umwelt. Um mit den permanenten Veränderungen klar zu kommen geht man davon aus, dass es von Vorteil ist wenn ein Organismus die Veränderungen wahrnehmen und vorausahnen kann. Die sogenannten Inneren Uhren ermöglichen dies und stellen möglicherweise einen Fitness Vorteil dar. Um den Mechanismus von Inneren Uhren zu untersuchen und aufzudecken benutzen Chronobiologen verschiedene Modellorganismen. In dieser Arbeit wurde Drosophila melanogaster, mit ihren etwa 150 Uhrneuronen welche die Innere Uhr im Zentralen Nervensystem darstellen, als Modellorganismus verwendet. Der molekulare Mechanismus und die ineinandergreifenden Rückkopplungsschleifen mit den Hauptakteuren period, timeless, clock und cycle werden seit den 1970ern erforscht und wurden bisher recht gut charakterisiert. Aber der Einfluss einer funktionellen Inneren Uhr in Kombination mit diversen Faktoren und die daraus resultierenden Fitness Vorteile wurden in nur wenigen Studien untersucht und bleiben zu großen Teilen unbekannt. Deshalb war es das Ziel dieser Arbeit den Einfluss von Drosophilas Innere Uhr auf die Fitness der Taufliege aufzudecken. Um dieses Ziel zu erreichen wurden verschiedene Faktoren – wie z.B. Tageslänge, Luftfeuchtigkeit und Futterqualität – in Wildtyp CS und drei verschiedenen period Mutanten – namentlich perL, perS und per01, welche alle eine Punktmutation tragen, welche die Freilauf-Periodenlänge verändert oder zu Arrhythmizität führt – sowie einem weiteren arrhythmischen Fliegenstamm, clkAR, untersucht. In Konkurrenzversuchen konkurrierten Wildtyp und Uhrmutanten über bis zu 63 Generationen unter normalen 24 Stunden Rhythmen mit jeweils 12 Stunden Licht/Tag und 12 Stunden Dunkelheit/Nacht oder unter T-Zyklen mit 19 oder 29 Stunden, entsprechend der Freilauf-Periodenlänge der Mutanten, oder Dauerlicht (LL) im Falle der arrhythmischen Mutante, sowie unter naturähnlichen Bedingungen im Feldversuch in zwei aufeinanderfolgenden Jahren. Im Gesamten war der Wildtyp den Uhrmutanten überlegen, unabhängig von den Umweltbedingungen. Da die perL Mutanten Ihre Freilauf-Periodenlänge deutlich verlängerten, wurden die Konkurrenzexperimente mit auf natürlicher Weise mit dem Wildtyp CS rückgekreuzten Fliegenstämmen wiederholt. Mit diesen Experimenten konnte gezeigt werden, dass der genetische Hintergrund der Fliegenstämme – welche teils für Jahrzehnte im Labor gehalten und nur wenige Male rückgekreuzt werden – sehr wichtig ist und die Fitness der Fliegen beeinflusst. Aber auch die Länge der Tage (19 h, 24 h oder 29 h) beeinflusst die Fitness der Fliegen und ermöglicht es Ihnen in höherem Anteil in einer Population unter Konkurrenz zu bestehen. Weitere Faktoren, welche das Überleben unter Konkurrenz möglicherweise beeinflussen können, wie z.B. eine Paarungspräferenz und Laufaktivität von homo- und heterozygoten Weibchen oder die Anzahl an Spermien, die pro Paarung übertragen werden, wurden untersucht. Diese Faktoren allein konnten jedoch die Ergebnisse der Konkurrenzversuche nicht erklären und spielen dabei keine oder nur geringfügige Rollen und stellen ein Beispiel für die Komplexität des ganzen Systems mit noch weiteren unbekannten Faktoren dar. Im Weiteren wurde das Laufverhalten von ganzen Fliegenpopulationen aufgezeichnet, um zu erforschen, ob eine Fliegenpopulation einen gemeinsamen Freilauf an Laufaktivität aufweist oder nicht. Und tatsächlich konnte zum ersten Mal das Laufverhalten von ganzen Populationen aufgezeichnet werden und Sozialer Kontakt als Zeitgeber für Drosophila melanogaster bestätigt werden. Zusätzlich wurde in dieser Arbeit relative Luftfeuchtigkeit und deren Auswirkung auf die Fitness der Fliegen, als auch als potentieller Zeitgeber untersucht. Die Fliegen wurden zum Schlupf und zur Entfaltung der Flügel unterschiedlichen Luftfeuchtigkeiten ausgesetzt und es wurden Phasenverschiebungsversuche mit Luftfeuchtigkeitszyklen durchgeführt, um diese zwei verschiedenen Fragen nach Fitness und potentiellem Zeitgeber zu beantworten. Die Fruchtfliege schlüpft normalerweise in den Morgenstunden, wenn die Luftfeuchtigkeit relativ hoch ist, weshalb im Allgemeinen angenommen wird, dass dies zu diesem Zeitpunkt des Tages geschieht, um eine Austrocknung zu verhindern. Die Ergebnisse dieser Arbeit waren sehr eindeutig und demonstrierten, dass die relative Luftfeuchtigkeit keinen großen Einfluss auf die Fitness der Fliegen in Bezug auf den Schlupferfolg und korrektes Entfalten der Flügel hat und dass die Temperatur wohl eher der ausschlaggebende Faktor sein könnte. In den Phasenverschiebungsversuchen mit Luftfeuchtigkeitszyklen konnte aufgedeckt werden, dass relative Luftfeuchtigkeit keinen Zeitgeber für Drosophila melanogaster darstellt, aber die Laufaktivität der Fliegen beeinflusst und maskiert, indem das Laufverhalten bei bestimmten relativen Luftfeuchtigkeiten zugelassen oder unterdrückt wird. Außerdem wurde die Lebenserwartung der Wildtyp und Uhrmutanten Fliegenstämme unter verschiedenen Tageslängen und mit unterschiedlicher Futterqualität untersucht, um den Einfluss dieser Faktoren auf die Fitness und somit das Überleben der Fliegen auf Dauer zu charakterisieren. Wie erwartet starben die Fliegen auf dem nährstoffarmen Minimalmedium früher als auf dem nährstoffreichen Maximalmedium, aber es konnte auch ein kleiner Effekt der Tageslänge gezeigt werden. Hierbei lebten die Fliegen etwas länger, wenn die Tageslänge die Freilauf-Periodenlänge der Fliegen widerspiegelte. Diese Versuche zeigten auch einen Fitness Vorteil der Wildtyp Fliegen gegenüber der Uhrmutanten auf lange Sicht, jedoch nicht zu Beginn (in den ersten ca. 2-3 Wochen). Abschließend kann zusammengefasst werden, dass genetische Variation wichtig ist, um sich an Veränderungen in der Umwelt anzupassen und die eigene Fitness und somit Überleben zu steigern. Eine funktionelle Innere Uhr mit einer Periodenlänge von etwa 24 Stunden zu besitzen stellt einen Fitness Vorteil für die Fliegen dar, zumindest unter Konkurrenzbedingungen. Das ganze System ist sehr komplex und viele Faktoren – bekannte und noch unbekannte – spielen eine Rolle in diesem System, welches auf verschiedenen Ebenen interagiert, wie z.B. auf physiologischer, metabolistischer oder auf der Verhaltensebene. KW - Taufliege KW - Drosophila KW - Biologische Uhr KW - Tageslänge KW - Luftfeuchtigkeit KW - Drosophila melanogaster KW - Fitness Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-211415 ER - TY - JOUR A1 - Vaze, Koustubh M. A1 - Helfrich-Förster, Charlotte T1 - Drosophila ezoana uses an hour-glass or highly damped circadian clock for measuring night length and inducing diapause JF - Physiological Entomology N2 - Insects inhabiting the temperate zones measure seasonal changes in day or night length to enter the overwintering diapause. Diapause induction occurs after the duration of the night exceeds a critical night length (CNL). Our understanding of the time measurement mechanisms is continuously evolving subsequent to Bünning’s proposal that circadian systems play the clock role in photoperiodic time measurement (Bünning, 1936). Initially, the photoperiodic clocks were considered to be either based on circadian oscillators or on simple hour-glasses, depending on ‘positive’ or ‘negative’ responses in Nanda–Hamner and Bünsow experiments (Nanda & Hammer, 1958; Bünsow, 1960). However, there are also species whose responses can be regarded as neither ‘positive’, nor as ‘negative’, such as the Northern Drosophila species Drosophila ezoana, which is investigated in the present study. In addition, modelling efforts show that the ‘positive’ and ‘negative’ Nanda–Hamner responses can also be provoked by circadian oscillators that are damped to different degrees: animals with highly sustained circadian clocks will respond ‘positive’ and those with heavily damped circadian clocks will respond ‘negative’. In the present study, an experimental assay is proposed that characterizes the photoperiodic oscillators by determining the effects of non-24-h light/dark cycles (T-cycles) on critical night length. It is predicted that there is (i) a change in the critical night length as a function of T-cycle period in sustained-oscillator-based clocks and (ii) a fxed night-length measurement (i.e. no change in critical night length) in damped-oscillator-based clocks. Drosophila ezoana flies show a critical night length of approximately 7 h irrespective of T-cycle period, suggesting a damped-oscillator-based photoperiodic clock. The conclusion is strengthened by activity recordings revealing that the activity rhythm of D. ezoana flies also dampens in constant darkness. KW - photoperiodic time mesurement KW - wyeomyia smithii KW - protophormia terraenovae KW - immunoreactive neurons KW - geographical variation KW - reproductive diapause KW - rhythmic components KW - locomotor activity KW - circadian clock KW - damped-oscillator-model of photoperiodic clock KW - diapause KW - Drosophila KW - hour-glass KW - pitcher-plant mosquito KW - bug riptortus-pedestris KW - Nanda-Hamner KW - photoperiodism Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-204278 VL - 41 IS - 4 ER - TY - JOUR A1 - Pütz, Stephanie M. T1 - Mbt/PAK4 together with SRC modulates N-Cadherin adherens junctions in the developing Drosophila eye JF - Biology Open N2 - Tissue morphogenesis is accompanied by changes of adherens junctions (AJ). During Drosophila eye development, AJ reorganization includes the formation of isolated N-Cadherin AJ between photoreceptors R3/R4. Little is known about how these N-Cadherin AJ are established and maintained. This study focuses on the kinases Mbt/PAK4 and SRC, both known to alter E-Cadherin AJ across phyla. Drosophila p21-activated kinase Mbt and the non-receptor tyrosine kinases Src64 and Src42 regulate proper N-Cadherin AJ. N-Cadherin AJ elongation depends on SRC kinase activity. Cell culture experiments demonstrate binding of both Drosophila SRC isoforms to N-Cadherin and its subsequent tyrosine phosphorylation. In contrast, Mbt stabilizes but does not bind N-Cadherin in vitro. Mbt is required in R3/R4 for zipping the N-Cadherin AJ between these cells, independent of its kinase activity and Cdc42-binding. The mbt phenotype can be reverted by mutations in Src64 and Src42. Because Mbt neither directly binds to SRC proteins nor has a reproducible influence on their kinase activity, the conclusion is that Mbt and SRC signaling converge on N-Cadherin. N-Cadherin AJ formation during eye development requires a proper balance between the promoting effects of Mbt and the inhibiting influences of SRC kinases. KW - Drosophila KW - Eye development KW - p21-activated kinase Mbt/PAK4 KW - Adherens junction Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-200898 VL - 8 ER - TY - JOUR A1 - Selcho, Mareike A1 - Millán, Carola A1 - Palacios-Muñoz, Angelina A1 - Ruf, Franziska A1 - Ubillo, Lilian A1 - Chen, Jiangtian A1 - Bergmann, Gregor A1 - Ito, Chihiro A1 - Silva, Valeria A1 - Wegener, Christian A1 - Ewer, John T1 - Central and peripheral clocks are coupled by a neuropeptide pathway in Drosophila JF - Nature Communications N2 - Animal circadian clocks consist of central and peripheral pacemakers, which are coordinated to produce daily rhythms in physiology and behaviour. Despite its importance for optimal performance and health, the mechanism of clock coordination is poorly understood. Here we dissect the pathway through which the circadian clock of Drosophila imposes daily rhythmicity to the pattern of adult emergence. Rhythmicity depends on the coupling between the brain clock and a peripheral clock in the prothoracic gland (PG), which produces the steroid hormone, ecdysone. Time information from the central clock is transmitted via the neuropeptide, sNPF, to non-clock neurons that produce the neuropeptide, PTTH. These secretory neurons then forward time information to the PG clock. We also show that the central clock exerts a dominant role on the peripheral clock. This use of two coupled clocks could serve as a paradigm to understand how daily steroid hormone rhythms are generated in animals. KW - circadian clock KW - Drosophila KW - neuropeptide pathway KW - peripheral clocks KW - central clocks Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-170831 VL - 8 IS - 15563 ER - TY - JOUR A1 - Chen, Yi-chun A1 - Mishra, Dushyant A1 - Gläß, Sebastian A1 - Gerber, Bertram T1 - Behavioral Evidence for Enhanced Processing of the Minor Component of Binary Odor Mixtures in Larval Drosophila JF - Frontiers in Psychology N2 - A fundamental problem in deciding between mutually exclusive options is that the decision needs to be categorical although the properties of the options often differ but in grade. We developed an experimental handle to study this aspect of behavior organization. Larval Drosophila were trained such that in one set of animals odor A was rewarded, but odor B was not (A+/B), whereas a second set of animals was trained reciprocally (A/B+). We then measured the preference of the larvae either for A, or for B, or for “morphed” mixtures of A and B, that is for mixtures differing in the ratio of the two components. As expected, the larvae showed higher preference when only the previously rewarded odor was presented than when only the previously unrewarded odor was presented. For mixtures of A and B that differed in the ratio of the two components, the major component dominated preference behavior—but it dominated less than expected from a linear relationship between mixture ratio and preference behavior. This suggests that a minor component can have an enhanced impact in a mixture, relative to such a linear expectation. The current paradigm may prove useful in understanding how nervous systems generate discrete outputs in the face of inputs that differ only gradually. KW - learning KW - memory KW - perception KW - compound conditioning KW - decision-making KW - Drosophila Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-170011 VL - 8 IS - 1923 ER -