@article{MrestaniLichterSirenetal.2023,
  author    = {Mrestani, Achmed and Lichter, Katharina and Sir{\´e}n, Anna-Leena and Heckmann, Manfred and Paul, Mila M. and Pauli, Martin},
  title     = {Single-molecule localization microscopy of presynaptic active zones in Drosophila melanogaster after rapid cryofixation},
  series = {International Journal of Molecular Sciences},
  volume    = {24},
  journal   = {International Journal of Molecular Sciences},
  number    = {3},
  issn      = {1422-0067},
  doi       = {10.3390/ijms24032128},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-304904},
  year      = {2023},
  abstract  = {Single-molecule localization microscopy (SMLM) greatly advances structural studies of diverse biological tissues. For example, presynaptic active zone (AZ) nanotopology is resolved in increasing detail. Immunofluorescence imaging of AZ proteins usually relies on epitope preservation using aldehyde-based immunocompetent fixation. Cryofixation techniques, such as high-pressure freezing (HPF) and freeze substitution (FS), are widely used for ultrastructural studies of presynaptic architecture in electron microscopy (EM). HPF/FS demonstrated nearer-to-native preservation of AZ ultrastructure, e.g., by facilitating single filamentous structures. Here, we present a protocol combining the advantages of HPF/FS and direct stochastic optical reconstruction microscopy (dSTORM) to quantify nanotopology of the AZ scaffold protein Bruchpilot (Brp) at neuromuscular junctions (NMJs) of Drosophila melanogaster. Using this standardized model, we tested for preservation of Brp clusters in different FS protocols compared to classical aldehyde fixation. In HPF/FS samples, presynaptic boutons were structurally well preserved with ~22\% smaller Brp clusters that allowed quantification of subcluster topology. In summary, we established a standardized near-to-native preparation and immunohistochemistry protocol for SMLM analyses of AZ protein clusters in a defined model synapse. Our protocol could be adapted to study protein arrangements at single-molecule resolution in other intact tissue preparations.},
  language  = {en}
}
@article{LamazeOeztuerkColakFischeretal.2017,
  author    = {Lamaze, Angelique and {\"O}zt{\"u}rk-{\c{C}}olak, Arzu and Fischer, Robin and Peschel, Nicolai and Koh, Kyunghee and Jepson, James E. C.},
  title     = {Regulation of sleep plasticity by a thermo-sensitive circuit in Drosophila},
  series = {Scientific Reports},
  volume    = {7},
  journal   = {Scientific Reports},
  doi       = {10.1038/srep40304},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-181146},
  pages     = {12},
  year      = {2017},
  abstract  = {Sleep is a highly conserved and essential behaviour in many species, including the fruit fly Drosophila melanogaster. In the wild, sensory signalling encoding environmental information must be integrated with sleep drive to ensure that sleep is not initiated during detrimental conditions. However, the molecular and circuit mechanisms by which sleep timing is modulated by the environment are unclear. Here we introduce a novel behavioural paradigm to study this issue. We show that in male fruit flies, onset of the daytime siesta is delayed by ambient temperatures above 29°C. We term this effect Prolonged Morning Wakefulness (PMW). We show that signalling through the TrpA1 thermo-sensor is required for PMW, and that TrpA1 specifically impacts siesta onset, but not night sleep onset, in response to elevated temperatures. We identify two critical TrpA1-expressing circuits and show that both contact DN1p clock neurons, the output of which is also required for PMW. Finally, we identify the circadian blue-light photoreceptor CRYPTOCHROME as a molecular regulator of PMW, and propose a model in which the Drosophila nervous system integrates information encoding temperature, light, and time to dynamically control when sleep is initiated. Our results provide a platform to investigate how environmental inputs co-ordinately regulate sleep plasticity.},
  language  = {en}
}
@article{ChenReiherHermannLuibletal.2016,
  author    = {Chen, Jiangtian and Reiher, Wencke and Hermann-Luibl, Christiane and Sellami, Azza and Cognigni, Paola and Kondo, Shu and Helfrich-F{\"o}rster, Charlotte and Veenstra, Jan A. and Wegener, Christian},
  title     = {Allatostatin A Signalling in Drosophila Regulates Feeding and Sleep and Is Modulated by PDF},
  series = {PLoS Genetics},
  volume    = {12},
  journal   = {PLoS Genetics},
  number    = {9},
  doi       = {10.1371/journal.pgen.1006346},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-178170},
  year      = {2016},
  abstract  = {Feeding and sleep are fundamental behaviours with significant interconnections and cross-modulations. The circadian system and peptidergic signals are important components of this modulation, but still little is known about the mechanisms and networks by which they interact to regulate feeding and sleep. We show that specific thermogenetic activation of peptidergic Allatostatin A (AstA)-expressing PLP neurons and enteroendocrine cells reduces feeding and promotes sleep in the fruit fly Drosophila. The effects of AstA cell activation are mediated by AstA peptides with receptors homolog to galanin receptors subserving similar and apparently conserved functions in vertebrates. We further identify the PLP neurons as a downstream target of the neuropeptide pigment-dispersing factor (PDF), an output factor of the circadian clock. PLP neurons are contacted by PDF-expressing clock neurons, and express a functional PDF receptor demonstrated by cAMP imaging. Silencing of AstA signalling and continuous input to AstA cells by tethered PDF changes the sleep/activity ratio in opposite directions but does not affect rhythmicity. Taken together, our results suggest that pleiotropic AstA signalling by a distinct neuronal and enteroendocrine AstA cell subset adapts the fly to a digestive energy-saving state which can be modulated by PDF.},
  language  = {en}
}
@article{BeerHelfrichFoerster2020,
  author    = {Beer, Katharina and Helfrich-F{\"o}rster, Charlotte},
  title     = {Model and Non-model Insects in Chronobiology},
  series = {Frontiers in Behavioral Neuroscience},
  volume    = {14},
  journal   = {Frontiers in Behavioral Neuroscience},
  issn      = {1662-5153},
  doi       = {10.3389/fnbeh.2020.601676},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-218721},
  year      = {2020},
  abstract  = {The fruit fly Drosophila melanogaster is an established model organism in chronobiology, because genetic manipulation and breeding in the laboratory are easy. The circadian clock neuroanatomy in D. melanogaster is one of the best-known clock networks in insects and basic circadian behavior has been characterized in detail in this insect. Another model in chronobiology is the honey bee Apis mellifera, of which diurnal foraging behavior has been described already in the early twentieth century. A. mellifera hallmarks the research on the interplay between the clock and sociality and complex behaviors like sun compass navigation and time-place-learning. Nevertheless, there are aspects of clock structure and function, like for example the role of the clock in photoperiodism and diapause, which can be only insufficiently investigated in these two models. Unlike high-latitude flies such as Chymomyza costata or D. ezoana, cosmopolitan D. melanogaster flies do not display a photoperiodic diapause. Similarly, A. mellifera bees do not go into "real" diapause, but most solitary bee species exhibit an obligatory diapause. Furthermore, sociality evolved in different Hymenoptera independently, wherefore it might be misleading to study the social clock only in one social insect. Consequently, additional research on non-model insects is required to understand the circadian clock in Diptera and Hymenoptera. In this review, we introduce the two chronobiology model insects D. melanogaster and A. mellifera, compare them with other insects and show their advantages and limitations as general models for insect circadian clocks.},
  language  = {en}
}
@article{RuppertFranzSaratisetal.2017,
  author    = {Ruppert, Manuela and Franz, Mirjam and Saratis, Anastasios and Escarcena, Laura Velo and Hendrich, Oliver and Gooi, Li Ming and Schwenkert, Isabell and Klebes, Ansgar and Scholz, Henrike},
  title     = {Hangover links nuclear RNA signaling to cAMP regulation via the phosphodiesterase 4d ortholog dunce},
  series = {Cell Reports},
  volume    = {18},
  journal   = {Cell Reports},
  number    = {2},
  doi       = {10.1016/j.celrep.2016.12.048},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-171950},
  pages     = {533-544},
  year      = {2017},
  abstract  = {The hangover gene defines a cellular stress pathway that is required for rapid ethanol tolerance in Drosophila melanogaster. To understand how cellular stress changes neuronal function, we analyzed Hangover function on a cellular and neuronal level. We provide evidence that Hangover acts as a nuclear RNA binding protein and we identified the phosphodiesterase 4d ortholog dunce as a target RNA. We generated a transcript-specific dunce mutant that is impaired not only in ethanol tolerance but also in the cellular stress response. At the neuronal level, Dunce and Hangover are required in the same neuron pair to regulate experience-dependent motor output. Within these neurons, two cyclic AMP (cAMP)-dependent mechanisms balance the degree of tolerance. The balance is achieved by feedback regulation of Hangover and dunce transcript levels. This study provides insight into how nuclear Hangover/RNA signaling is linked to the cytoplasmic regulation of cAMP levels and results in neuronal adaptation and behavioral changes.},
  language  = {en}
}
@article{FischerHelfrichFoersterPeschel2016,
  author    = {Fischer, Robin and Helfrich-F{\"o}rster, Charlotte and Peschel, Nicolai},
  title     = {GSK-3 Beta Does Not Stabilize Cryptochrome in the Circadian Clock of Drosophila},
  series = {PLoS ONE},
  volume    = {11},
  journal   = {PLoS ONE},
  number    = {1},
  doi       = {10.1371/journal.pone.0146571},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-180370},
  year      = {2016},
  abstract  = {Cryptochrome (CRY) is the primary photoreceptor of Drosophila's circadian clock. It resets the circadian clock by promoting light-induced degradation of the clock protein Timeless (TIM) in the proteasome. Under constant light, the clock stops because TIM is absent, and the flies become arrhythmic. In addition to TIM degradation, light also induces CRY degradation. This depends on the interaction of CRY with several proteins such as the E3 ubiquitin ligases Jetlag (JET) and Ramshackle (BRWD3). However, CRY can seemingly also be stabilized by interaction with the kinase Shaggy (SGG), the GSK-3 beta fly orthologue. Consequently, flies with SGG overexpression in certain dorsal clock neurons are reported to remain rhythmic under constant light. We were interested in the interaction between CRY, Ramshackle and SGG and started to perform protein interaction studies in S2 cells. To our surprise, we were not able to replicate the results, that SGG overexpression does stabilize CRY, neither in S2 cells nor in the relevant clock neurons. SGG rather does the contrary. Furthermore, flies with SGG overexpression in the dorsal clock neurons became arrhythmic as did wild-type flies. Nevertheless, we could reproduce the published interaction of SGG with TIM, since flies with SGG overexpression in the lateral clock neurons shortened their free-running period. We conclude that SGG does not directly interact with CRY but rather with TIM. Furthermore we could demonstrate, that an unspecific antibody explains the observed stabilization effects on CRY.},
  language  = {en}
}
@article{KoenigWolfHeisenberg2016,
  author    = {Koenig, Sebastian and Wolf, Reinhard and Heisenberg, Martin},
  title     = {Vision in Flies: Measuring the Attention Span},
  series = {PLoS ONE},
  volume    = {11},
  journal   = {PLoS ONE},
  number    = {2},
  doi       = {10.1371/journal.pone.0148208},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-179947},
  year      = {2016},
  abstract  = {A visual stimulus at a particular location of the visual field may elicit a behavior while at the same time equally salient stimuli in other parts do not. This property of visual systems is known as selective visual attention (SVA). The animal is said to have a focus of attention (FoA) which it has shifted to a particular location. Visual attention normally involves an attention span at the location to which the FoA has been shifted. Here the attention span is measured in Drosophila. The fly is tethered and hence has its eyes fixed in space. It can shift its FoA internally. This shift is revealed using two simultaneous test stimuli with characteristic responses at their particular locations. In tethered flight a wild type fly keeps its FoA at a certain location for up to 4s. Flies with a mutation in the radish gene, that has been suggested to be involved in attention-like mechanisms, display a reduced attention span of only 1s.},
  language  = {en}
}
@article{KoenigWolfHeisenberg2016,
  author    = {Koenig, Sebastian and Wolf, Reinhard and Heisenberg, Martin},
  title     = {Visual Attention in Flies-Dopamine in the Mushroom Bodies Mediates the After-Effect of Cueing},
  series = {PLoS ONE},
  volume    = {11},
  journal   = {PLoS ONE},
  number    = {8},
  doi       = {10.1371/journal.pone.0161412},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-179564},
  year      = {2016},
  abstract  = {Visual environments may simultaneously comprise stimuli of different significance. Often such stimuli require incompatible responses. Selective visual attention allows an animal to respond exclusively to the stimuli at a certain location in the visual field. In the process of establishing its focus of attention the animal can be influenced by external cues. Here we characterize the behavioral properties and neural mechanism of cueing in the fly Drosophila melanogaster. A cue can be attractive, repulsive or ineffective depending upon (e.g.) its visual properties and location in the visual field. Dopamine signaling in the brain is required to maintain the effect of cueing once the cue has disappeared. Raising or lowering dopamine at the synapse abolishes this after-effect. Specifically, dopamine is necessary and sufficient in the αβ-lobes of the mushroom bodies. Evidence is provided for an involvement of the αβ\(_{posterior}\) Kenyon cells.},
  language  = {en}
}
@article{AppelScholzKocabeyetal.2016,
  author    = {Appel, Mirjam and Scholz, Claus-J{\"u}rgen and Kocabey, Samet and Savage, Sinead and K{\"o}nig, Christian and Yarali, Ayse},
  title     = {Independent natural genetic variation of punishment- versus relief-memory},
  series = {Biology Letters},
  volume    = {12},
  journal   = {Biology Letters},
  number    = {12},
  doi       = {10.1098/rsbl.2016.0657},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-186554},
  pages     = {20160657},
  year      = {2016},
  abstract  = {A painful event establishes two opponent memories: cues that are associated with pain onset are remembered negatively, whereas cues that coincide with the relief at pain offset acquire positive valence. Such punishment-versus relief-memories are conserved across species, including humans, and the balance between them is critical for adaptive behaviour with respect to pain and trauma. In the fruit fly, Drosophila melanogaster as a study case, we found that both punishment-and relief-memories display natural variation across wild-derived inbred strains, but they do not covary, suggesting a considerable level of dissociation in their genetic effectors. This provokes the question whether there may be heritable inter-individual differences in the balance between these opponent memories in man, with potential psycho-clinical implications.},
  language  = {en}
}
@article{RufFraunholzOechsneretal.2017,
  author    = {Ruf, Franziska and Fraunholz, Martin and {\"O}chsner, Konrad and Kaderschabeck, Johann and Wegener, Christian},
  title     = {WEclMon - A simple and robust camera-based system to monitor Drosophila eclosion under optogenetic manipulation and natural conditions},
  series = {PLoS ONE},
  volume    = {12},
  journal   = {PLoS ONE},
  number    = {6},
  doi       = {10.1371/journal.pone.0180238},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170755},
  pages     = {e0180238},
  year      = {2017},
  abstract  = {Eclosion in flies and other insects is a circadian-gated behaviour under control of a central and a peripheral clock. It is not influenced by the motivational state of an animal, and thus presents an ideal paradigm to study the relation and signalling pathways between central and peripheral clocks, and downstream peptidergic regulatory systems. Little is known, however, about eclosion rhythmicity under natural conditions, and research into this direction is hampered by the physically closed design of current eclosion monitoring systems. We describe a novel open eclosion monitoring system (WEclMon) that allows the puparia to come into direct contact with light, temperature and humidity. We demonstrate that the system can be used both in the laboratory and outdoors, and shows a performance similar to commercial closed funnel-type monitors. Data analysis is semi-automated based on a macro toolset for the open imaging software Fiji. Due to its open design, the WEclMon is also well suited for optogenetic experiments. A small screen to identify putative neuroendocrine signals mediating time from the central clock to initiate eclosion showed that optogenetic activation of ETH-, EH and myosuppressin neurons can induce precocious eclosion. Genetic ablation of myosuppressin-expressing neurons did, however, not affect eclosion rhythmicity.},
  language  = {en}
}