@article{SchaeblerAmatobiHornetal.2020, author = {Sch{\"a}bler, Stefan and Amatobi, Kelechi M. and Horn, Melanie and Rieger, Dirk and Helfrich‑F{\"o}rster, Charlotte and Mueller, Martin J. and Wegener, Christian and Fekete, Agnes}, title = {Loss of function in the Drosophila clock gene period results in altered intermediary lipid metabolism and increased susceptibility to starvation}, series = {Cellular and Molecular Life Sciences}, volume = {77}, journal = {Cellular and Molecular Life Sciences}, issn = {1420-682X}, doi = {10.1007/s00018-019-03441-6}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-232432}, pages = {4939-4956}, year = {2020}, abstract = {The fruit fly Drosophila is a prime model in circadian research, but still little is known about its circadian regulation of metabolism. Daily rhythmicity in levels of several metabolites has been found, but knowledge about hydrophobic metabolites is limited. We here compared metabolite levels including lipids between period\(^{01}\) (per\(^{01}\)) clock mutants and Canton-S wildtype (WT\(_{CS}\)) flies in an isogenic and non-isogenic background using LC-MS. In the non-isogenic background, metabo-lites with differing levels comprised essential amino acids, kynurenines, pterinates, glycero(phospho)lipids, and fatty acid esters. Notably, detectable diacylglycerols (DAG) and acylcarnitines (AC), involved in lipid metabolism, showed lower levels in per\(^{01}\) mutants. Most of these differences disappeared in the isogenic background, yet the level differences for AC as well as DAG were consistent for fly bodies. AC levels were dependent on the time of day in WTCS in phase with food consumption under LD conditions, while DAGs showed weak daily oscillations. Two short-chain ACs continued to cycle even in constant darkness. per\(^{01}\) mutants in LD showed no or very weak diel AC oscillations out of phase with feeding activity. The low levels of DAGs and ACs in per\(^{01}\) did not correlate with lower total food consumption, body mass or weight. Clock mutant flies showed higher sensitivity to starvation independent of their background-dependent activity level. Our results suggest that neither feeding, energy storage nor mobilisation is significantly affected in per\(^{01}\) mutants, but point towards impaired mitochondrial activity, supported by upregulation of the mitochondrial stress marker 4EBP in the clock mutants}, language = {en} } @article{MildnerRoces2016, author = {Mildner, Stephanie and Roces, Flavio}, title = {Plasticity of Daily Behavioral Rhythms in Foragers and Nurses of the Ant Camponotus rufipes: Influence of Social Context and Feeding Times}, series = {PLoS One}, volume = {12}, journal = {PLoS One}, number = {1}, doi = {10.1371/journal.pone.0169244}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-148010}, pages = {e0169244}, year = {2016}, abstract = {Daily activities within an ant colony need precise temporal organization, and an endogenous clock appears to be essential for such timing processes. A clock drives locomotor rhythms in isolated workers in a number of ant species, but its involvement in activities displayed in the social context is unknown. We compared locomotor rhythms in isolated individuals and behavioral rhythms in the social context of workers of the ant Camponotus rufipes. Both forager and nurse workers exhibited circadian rhythms in locomotor activity under constant conditions, indicating the involvement of an endogenous clock. Activity was mostly nocturnal and synchronized with the 12:12h light-dark-cycle. To evaluate whether rhythmicity was maintained in the social context and could be synchronized with non-photic zeitgebers such as feeding times, daily behavioral activities of single workers inside and outside the nest were quantified continuously over 24 hours in 1656 hours of video recordings. Food availability was limited to a short time window either at day or at night, thus mimicking natural conditions of temporally restricted food access. Most foragers showed circadian foraging behavior synchronized with food availability, either at day or nighttime. When isolated thereafter in single locomotor activity monitors, foragers mainly displayed arrhythmicity. Here, high mortality suggested potential stressful effects of the former restriction of food availability. In contrast, nurse workers showed high overall activity levels in the social context and performed their tasks all around the clock with no circadian pattern, likely to meet the needs of the brood. In isolation, the same individuals exhibited in turn strong rhythmic activity and nocturnality. Thus, endogenous activity rhythms were inhibited in the social context, and timing of daily behaviors was flexibly adapted to cope with task demands. As a similar socially-mediated plasticity in circadian rhythms was already shown in honey bees, the temporal organization in C. rufipes and honey bees appear to share similar basic features.}, language = {en} } @article{JoschinskiHovestadtKrauss2015, author = {Joschinski, Jens and Hovestadt, Thomas and Krauss, Jochen}, title = {Coping with shorter days: do phenology shifts constrain aphid fitness?}, series = {PeerJ}, volume = {3}, journal = {PeerJ}, number = {e1103}, doi = {10.7717/peerj.1103}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-148382}, year = {2015}, abstract = {Climate change can alter the phenology of organisms. It may thus lead seasonal organisms to face different day lengths than in the past, and the fitness consequences of these changes are as yet unclear. To study such effects, we used the pea aphid Acyrthosiphon pisum as a model organism, as it has obligately asexual clones which can be used to study day length effects without eliciting a seasonal response. We recorded life-history traits under short and long days, both with two realistic temperature cycles with means differing by 2 °C. In addition, we measured the population growth of aphids on their host plant Pisum sativum. We show that short days reduce fecundity and the length of the reproductive period of aphids. Nevertheless, this does not translate into differences at the population level because the observed fitness costs only become apparent late in the individual's life. As expected, warm temperature shortens the development time by 0.7 days/°C, leading to faster generation times. We found no interaction of temperature and day length. We conclude that day length changes cause only relatively mild costs, which may not decelerate the increase in pest status due to climate change.}, 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{DusikSenthilanMentzeletal.2014, author = {Dusik, Verena and Senthilan, Pingkalai R. and Mentzel, Benjamin and Hartlieb, Heiko and W{\"u}lbeck, Corina and Yoshii, Taishi and Raabe, Thomas and Helfrich-F{\"o}rster, Charlotte}, title = {The MAP Kinase p38 Is Part of Drosophila melanogaster's Circadian Clock}, series = {PLoS Genetics}, volume = {10}, journal = {PLoS Genetics}, number = {8}, issn = {1553-7404}, doi = {10.1371/journal.pgen.1004565}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-119433}, pages = {e1004565}, year = {2014}, abstract = {All organisms have to adapt to acute as well as to regularly occurring changes in the environment. To deal with these major challenges organisms evolved two fundamental mechanisms: the p38 mitogen-activated protein kinase (MAPK) pathway, a major stress pathway for signaling stressful events, and circadian clocks to prepare for the daily environmental changes. Both systems respond sensitively to light. Recent studies in vertebrates and fungi indicate that p38 is involved in light-signaling to the circadian clock providing an interesting link between stress-induced and regularly rhythmic adaptations of animals to the environment, but the molecular and cellular mechanisms remained largely unknown. Here, we demonstrate by immunocytochemical means that p38 is expressed in Drosophila melanogaster's clock neurons and that it is activated in a clock-dependent manner. Surprisingly, we found that p38 is most active under darkness and, besides its circadian activation, additionally gets inactivated by light. Moreover, locomotor activity recordings revealed that p38 is essential for a wild-type timing of evening activity and for maintaining ∼ 24 h behavioral rhythms under constant darkness: flies with reduced p38 activity in clock neurons, delayed evening activity and lengthened the period of their free-running rhythms. Furthermore, nuclear translocation of the clock protein Period was significantly delayed on the expression of a dominant-negative form of p38b in Drosophila's most important clock neurons. Western Blots revealed that p38 affects the phosphorylation degree of Period, what is likely the reason for its effects on nuclear entry of Period. In vitro kinase assays confirmed our Western Blot results and point to p38 as a potential "clock kinase" phosphorylating Period. Taken together, our findings indicate that the p38 MAP Kinase is an integral component of the core circadian clock of Drosophila in addition to playing a role in stress-input pathways.}, 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{BarreaVetraniAltierietal.2021, author = {Barrea, Luigi and Vetrani, Claudia and Altieri, Barbara and Verde, Ludovica and Savastano, Silvia and Colao, Annamaria and Muscogiuri, Giovanna}, title = {The importance of being a 'lark' in post-menopausal women with obesity: a ploy to prevent type 2 diabetes mellitus?}, series = {Nutrients}, volume = {13}, journal = {Nutrients}, number = {11}, issn = {2072-6643}, doi = {10.3390/nu13113762}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-248572}, year = {2021}, abstract = {Chronotype is defined as the behavioral manifestation of circadian rhythms related to the external light-dark cycle. Evening chronotype has been associated with an increased risk of developing cardiometabolic diseases in obesity. Menopause is a lifestage associated with an increased risk of developing cardiometabolic diseases and a change in circadian rhythmicity compared to pre-menopause. However, the prevalence of chronotype categories in menopause and their role in determining menopause-related cardiometabolic risk, mostly in obesity, have not been investigated. Thus, we aimed to investigate the prevalence of chronotype categories in post-menopausal women with obesity and their role in menopause-related cardiometabolic risk. In this cross-sectional study we enrolled 49 pre-menopausal and 74 post-menopausal women with obesity. Anthropometric parameters, lifestyle habits, adherence to the Mediterranean Diet (MD), sleep quality, chronotype and the presence of type 2 diabetes mellitus (T2DM) and cardiovascular diseases (CVD) were studied. No significance differences were detected in terms of lifestyle and adherence to the MD between pre- and post-menopausal women. Chronotype was classified as morning in 66 (53.6\%), evening in 20 (16.3\%) and intermediate in 37 (30.1\%) women. In addition, pre-menopausal women with obesity showed a significantly higher chance to have an intermediate chronotype (OR = 2.21, 95\% CI 1.28-3.83; p = 0.004), whereas post-menopausal women with obesity showed a trend to have a higher morning chronotype (OR = 1.42, 95\% CI 0.98-2.06; p = 0.051), although this did not reach statistical significance. No significant differences were detected in terms of prevalence of evening chronotype between the two groups. However, the evening chronotype had a significantly higher risk to have T2DM compared to the morning (OR = 17.29, 95\% CI 2.40-124.27; p = 0.005) and intermediate chronotypes (OR = 30.86, 95\% CI 2.05-464.32; p = 0.013) in both pre- and post-menopausal women with obesity. In conclusion, the intermediate chronotype was significantly more prevalent in pre-menopausal women with obesity compared to post-menopausal women. Evening chronotype was associated to T2DM in both pre- and post-menopause. These results support the importance of including the assessment of chronotype in the management of women with obesity in post-menopause.}, language = {en} }