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Brown MP, Verma S, Palmer I, Guerrero Zuniga A, Mehta A, Rosensweig C, Keles MF, Wu MN. A subclass of evening cells promotes the switch from arousal to sleep at dusk. Curr Biol 2024; 34:2186-2199.e3. [PMID: 38723636 PMCID: PMC11111347 DOI: 10.1016/j.cub.2024.04.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 03/20/2024] [Accepted: 04/17/2024] [Indexed: 05/21/2024]
Abstract
Animals exhibit rhythmic patterns of behavior that are shaped by an internal circadian clock and the external environment. Although light intensity varies across the day, there are particularly robust differences at twilight (dawn/dusk). These periods are also associated with major changes in behavioral states, such as the transition from arousal to sleep. However, the neural mechanisms by which time and environmental conditions promote these behavioral transitions are poorly defined. Here, we show that the E1 subclass of Drosophila evening clock neurons promotes the transition from arousal to sleep at dusk. We first demonstrate that the cell-autonomous clocks of E2 neurons primarily drive and adjust the phase of evening anticipation, the canonical behavior associated with "evening" clock neurons. We next show that conditionally silencing E1 neurons causes a significant delay in sleep onset after dusk. However, rather than simply promoting sleep, activating E1 neurons produces time- and light-dependent effects on behavior. Activation of E1 neurons has no effect early in the day but then triggers arousal before dusk and induces sleep after dusk. Strikingly, these activation-induced phenotypes depend on the presence of light during the day. Despite their influence on behavior around dusk, in vivo voltage imaging of E1 neurons reveals that their spiking rate and pattern do not significantly change throughout the day. Moreover, E1-specific clock ablation has no effect on arousal or sleep. Thus, we suggest that, rather than specifying "evening" time, E1 neurons act, in concert with other rhythmic neurons, to promote behavioral transitions at dusk.
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Affiliation(s)
- Matthew P Brown
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Shubha Verma
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Isabelle Palmer
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, USA
| | | | - Anuradha Mehta
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Clark Rosensweig
- Department of Neurobiology, Northwestern University, Evanston, IL 60201, USA
| | - Mehmet F Keles
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Mark N Wu
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA; Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, USA.
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2
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Manoli G, Zandawala M, Yoshii T, Helfrich-Förster C. Characterization of clock-related proteins and neuropeptides in Drosophila littoralis and their putative role in diapause. J Comp Neurol 2023; 531:1525-1549. [PMID: 37493077 DOI: 10.1002/cne.25522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 05/25/2023] [Accepted: 06/26/2023] [Indexed: 07/27/2023]
Abstract
Insects from high latitudes spend the winter in a state of overwintering diapause, which is characterized by arrested reproduction, reduced food intake and metabolism, and increased life span. The main trigger to enter diapause is the decreasing day length in summer-autumn. It is thus assumed that the circadian clock acts as an internal sensor for measuring photoperiod and orchestrates appropriate seasonal changes in physiology and metabolism through various neurohormones. However, little is known about the neuronal organization of the circadian clock network and the neurosecretory system that controls diapause in high-latitude insects. We addressed this here by mapping the expression of clock proteins and neuropeptides/neurohormones in the high-latitude fly Drosophila littoralis. We found that the principal organization of both systems is similar to that in Drosophila melanogaster, but with some striking differences in neuropeptide expression levels and patterns. The small ventrolateral clock neurons that express pigment-dispersing factor (PDF) and short neuropeptide F (sNPF) and are most important for robust circadian rhythmicity in D. melanogaster virtually lack PDF and sNPF expression in D. littoralis. In contrast, dorsolateral clock neurons that express ion transport peptide in D. melanogaster additionally express allatostatin-C and appear suited to transfer day-length information to the neurosecretory system of D. littoralis. The lateral neurosecretory cells of D. littoralis contain more neuropeptides than D. melanogaster. Among them, the cells that coexpress corazonin, PDF, and diuretic hormone 44 appear most suited to control diapause. Our work sets the stage to investigate the roles of these diverse neuropeptides in regulating insect diapause.
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Affiliation(s)
- Giulia Manoli
- Neurobiology and Genetics, Biocenter, University of Würzburg, Würzburg, Germany
| | - Meet Zandawala
- Neurobiology and Genetics, Biocenter, University of Würzburg, Würzburg, Germany
| | - Taishi Yoshii
- Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan
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3
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Majcin Dorcikova M, Duret LC, Pottié E, Nagoshi E. Circadian clock disruption promotes the degeneration of dopaminergic neurons in male Drosophila. Nat Commun 2023; 14:5908. [PMID: 37737209 PMCID: PMC10516932 DOI: 10.1038/s41467-023-41540-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 09/08/2023] [Indexed: 09/23/2023] Open
Abstract
Sleep and circadian rhythm disruptions are frequent comorbidities of Parkinson's disease (PD), a disorder characterized by the progressive loss of dopaminergic (DA) neurons in the substantia nigra. However, the causal role of circadian clocks in the degenerative process remains uncertain. We demonstrated here that circadian clocks regulate the rhythmicity and magnitude of the vulnerability of DA neurons to oxidative stress in male Drosophila. Circadian pacemaker neurons are presynaptic to a subset of DA neurons and rhythmically modulate their susceptibility to degeneration. The arrhythmic period (per) gene null mutation exacerbates the age-dependent loss of DA neurons and, in combination with brief oxidative stress, causes premature animal death. These findings suggest that circadian clock disruption promotes dopaminergic neurodegeneration.
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Affiliation(s)
- Michaëla Majcin Dorcikova
- Department of Genetics and Evolution and Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, CH-1211, Geneva, Switzerland
| | - Lou C Duret
- Department of Genetics and Evolution and Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, CH-1211, Geneva, Switzerland
| | - Emma Pottié
- Department of Genetics and Evolution and Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, CH-1211, Geneva, Switzerland
| | - Emi Nagoshi
- Department of Genetics and Evolution and Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, CH-1211, Geneva, Switzerland.
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4
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Lee GG, Zeng K, Duffy CM, Sriharsha Y, Yoo S, Park JH. In vivo characterization of the maturation steps of a pigment dispersing factor neuropeptide precursor in the Drosophila circadian pacemaker neurons. Genetics 2023; 225:iyad118. [PMID: 37364299 PMCID: PMC10471210 DOI: 10.1093/genetics/iyad118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 05/19/2023] [Accepted: 06/13/2023] [Indexed: 06/28/2023] Open
Abstract
Pigment dispersing factor (PDF) is a key signaling molecule coordinating the neuronal network associated with the circadian rhythms in Drosophila. The precursor (proPDF) of the mature PDF (mPDF) consists of 2 motifs, a larger PDF-associated peptide (PAP) and PDF. Through cleavage and amidation, the proPDF is predicted to produce cleaved-PAP (cPAP) and mPDF. To delve into the in vivo mechanisms underlying proPDF maturation, we generated various mutations that eliminate putative processing sites and then analyzed the effect of each mutation on the production of cPAP and mPDF by 4 different antibodies in both ectopic and endogenous conditions. We also assessed the knockdown effects of processing enzymes on the proPDF maturation. At the functional level, circadian phenotypes were measured for all mutants and knockdown lines. As results, we confirm the roles of key enzymes and their target residues: Amontillado (Amon) for the cleavage at the consensus dibasic KR site, Silver (Svr) for the removal of C-terminal basic residues from the intermediates, PAP-KR and PDF-GK, derived from proPDF, and PHM (peptidylglycine-α-hydroxylating monooxygenase) for the amidation of PDF. Our results suggest that the C-terminal amidation occurs independently of proPDF cleavage. Moreover, the PAP domain is important for the proPDF trafficking into the secretory vesicles and a close association between cPAP and mPDF following cleavage seems required for their stability within the vesicles. These studies highlight the biological significance of individual processing steps and the roles of the PAP for the stability and function of mPDF which is essential for the circadian clockworks.
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Affiliation(s)
- Gyunghee G Lee
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Kevin Zeng
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Cole M Duffy
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Yadali Sriharsha
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Siuk Yoo
- Department of Life Sciences, Yeungnam University, Gyeongsan, Gyeongbuk 38541, Korea
| | - Jae H Park
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
- Genome Science and Technology Graduate Program, University of Tennessee, Knoxville, TN 37996, USA
- NeuroNET Research Center, University of Tennessee, Knoxville, TN 37996, USA
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5
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Brown MP, Verma S, Palmer I, Zuniga AG, Rosensweig C, Keles MF, Wu MN. A subclass of evening cells promotes the switch from arousal to sleep at dusk. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.28.555147. [PMID: 37693540 PMCID: PMC10491161 DOI: 10.1101/2023.08.28.555147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Animals exhibit rhythmic patterns of behavior that are shaped by an internal circadian clock and the external environment. While light intensity varies across the day, there are particularly robust differences at twilight (dawn/dusk). These periods are also associated with major changes in behavioral states, such as the transition from arousal to sleep. However, the neural mechanisms by which time and environmental conditions promote these behavioral transitions are poorly defined. Here, we show that the E1 subclass of Drosophila evening clock neurons promotes the transition from arousal to sleep at dusk. We first demonstrate that the cell-autonomous clocks of E2 neurons alone are required to drive and adjust the phase of evening anticipation, the canonical behavior associated with "evening" clock neurons. We next show that conditionally silencing E1 neurons causes a significant delay in sleep onset after dusk. However, rather than simply promoting sleep, activating E1 neurons produces time- and light- dependent effects on behavior. Activation of E1 neurons has no effect early in the day, but then triggers arousal before dusk and induces sleep after dusk. Strikingly, these phenotypes critically depend on the presence of light during the day. Despite their influence on behavior around dusk, in vivo voltage imaging of E1 neurons reveals that their spiking rate does not vary between dawn and dusk. Moreover, E1-specific clock ablation has no effect on arousal or sleep. Thus, we suggest that, rather than specifying "evening" time, E1 neurons act, in concert with other rhythmic neurons, to promote behavioral transitions at dusk.
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Affiliation(s)
- Matthew P. Brown
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, U.S.A
| | - Shubha Verma
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, U.S.A
| | - Isabelle Palmer
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, U.S.A
| | | | - Clark Rosensweig
- Department of Neurobiology, Northwestern University, Evanston, IL 60201, U.S.A
| | - Mehmet F. Keles
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, U.S.A
| | - Mark N. Wu
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, U.S.A
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, U.S.A
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6
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Kobayashi R, Nakane S, Tomita J, Funato H, Yanagisawa M, Kume K. A phosphorylation-deficient mutant of Sik3, a homolog of Sleepy, alters circadian sleep regulation by PDF neurons in Drosophila. Front Neurosci 2023; 17:1181555. [PMID: 37662102 PMCID: PMC10469759 DOI: 10.3389/fnins.2023.1181555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 07/25/2023] [Indexed: 09/05/2023] Open
Abstract
Sleep behavior has been observed from non-vertebrates to humans. Sleepy mutation in mice resulted in a notable increase in sleep and was identified as an exon-skipping mutation of the salt-inducible kinase 3 (Sik3) gene, conserved among animals. The skipped exon includes a serine residue that is phosphorylated by protein kinase A. Overexpression of a mutant gene with the conversion of this serine into alanine (Sik3-SA) increased sleep in both mice and the fruit fly Drosophila melanogaster. However, the mechanism by which Sik3-SA increases sleep remains unclear. Here, we found that Sik3-SA overexpression in all neurons increased sleep under both light-dark (LD) conditions and constant dark (DD) conditions in Drosophila. Additionally, overexpression of Sik3-SA only in PDF neurons, which are a cluster of clock neurons regulating the circadian rhythm, increased sleep during subjective daytime while decreasing the amplitude of circadian rhythm. Furthermore, suppressing Sik3-SA overexpression specifically in PDF neurons in flies overexpressing Sik3-SA in all neurons reversed the sleep increase during subjective daytime. These results indicate that Sik3-SA alters the circadian function of PDF neurons and leads to an increase in sleep during subjective daytime under constant dark conditions.
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Affiliation(s)
- Riho Kobayashi
- Department of Neuropharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Shin Nakane
- Department of Neuropharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Jun Tomita
- Department of Neuropharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Hiromasa Funato
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Japan
- School of Medicine, Toho University, Tokyo, Japan
| | - Masashi Yanagisawa
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Japan
| | - Kazuhiko Kume
- Department of Neuropharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
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7
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Richhariya S, Shin D, Le JQ, Rosbash M. Dissecting neuron-specific functions of circadian genes using modified cell-specific CRISPR approaches. Proc Natl Acad Sci U S A 2023; 120:e2303779120. [PMID: 37428902 PMCID: PMC10629539 DOI: 10.1073/pnas.2303779120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 06/07/2023] [Indexed: 07/12/2023] Open
Abstract
Circadian behavioral rhythms in Drosophila melanogaster are regulated by about 75 pairs of brain neurons. They all express the core clock genes but have distinct functions and gene expression profiles. To understand the importance of these distinct molecular programs, neuron-specific gene manipulations are essential. Although RNAi based methods are standard to manipulate gene expression in a cell-specific manner, they are often ineffective, especially in assays involving smaller numbers of neurons or weaker Gal4 drivers. We and others recently exploited a neuron-specific CRISPR-based method to mutagenize genes within circadian neurons. Here, we further explore this approach to mutagenize three well-studied clock genes: the transcription factor gene vrille, the photoreceptor gene Cryptochrome (cry), and the neuropeptide gene Pdf (pigment dispersing factor). The CRISPR-based strategy not only reproduced their known phenotypes but also assigned cry function for different light-mediated phenotypes to discrete, different subsets of clock neurons. We further tested two recently published methods for temporal regulation in adult neurons, inducible Cas9 and the auxin-inducible gene expression system. The results were not identical, but both approaches successfully showed that the adult-specific knockout of the neuropeptide Pdf reproduces the canonical loss-of-function mutant phenotypes. In summary, a CRISPR-based strategy is a highly effective, reliable, and general method to temporally manipulate gene function in specific adult neurons.
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8
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Liang X, Holy TE, Taghert PH. Polyphasic circadian neural circuits drive differential activities in multiple downstream rhythmic centers. Curr Biol 2023; 33:351-363.e3. [PMID: 36610393 PMCID: PMC9877191 DOI: 10.1016/j.cub.2022.12.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 12/05/2022] [Accepted: 12/09/2022] [Indexed: 01/08/2023]
Abstract
Circadian clocks align various behaviors such as locomotor activity, sleep/wake, feeding, and mating to times of day that are most adaptive. How rhythmic information in pacemaker circuits is translated to neuronal outputs is not well understood. Here, we used brain-wide, 24-h in vivo calcium imaging in the Drosophila brain and searched for circadian rhythmic activity among identified clusters of dopaminergic (DA) and peptidergic neurosecretory (NS) neurons. Such rhythms were widespread and imposed by the PERIOD-dependent clock activity within the ∼150-cell circadian pacemaker network. The rhythms displayed either a morning (M), evening (E), or mid-day (MD) phase. Different subgroups of circadian pacemakers imposed neural activity rhythms onto different downstream non-clock neurons. Outputs from the canonical M and E pacemakers converged to regulate DA-PPM3 and DA-PAL neurons. E pacemakers regulate the evening-active DA-PPL1 neurons. In addition to these canonical M and E oscillators, we present evidence for a third dedicated phase occurring at mid-day: the l-LNv pacemakers present the MD activity peak, and they regulate the MD-active DA-PPM1/2 neurons and three distinct NS cell types. Thus, the Drosophila circadian pacemaker network is a polyphasic rhythm generator. It presents dedicated M, E, and MD phases that are functionally transduced as neuronal outputs to organize diverse daily activity patterns in downstream circuits.
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Affiliation(s)
- Xitong Liang
- Department of Neuroscience, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Timothy E Holy
- Department of Neuroscience, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Paul H Taghert
- Department of Neuroscience, Washington University in St. Louis, St. Louis, MO 63110, USA.
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9
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Mishra S, Sharma N, Singh SK, Lone SR. Peculiar sleep features in sympatric species may contribute to the temporal segregation. J Comp Physiol B 2023; 193:57-70. [PMID: 36271924 DOI: 10.1007/s00360-022-01463-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 09/13/2022] [Accepted: 09/20/2022] [Indexed: 01/24/2023]
Abstract
Sleep is conserved in the animal kingdom and plays a pivotal role in the adaptation of species. Sleep in Drosophila melanogaster is defined as any continuous 5 min of quiescence, shows a prominent siesta, and consolidated nighttime sleep. Here, we analyzed the sleep of two other species D. malerkotliana (DMK) and D. ananassae (DA), and compared it with D. melanogaster (DM). The DMK males and females have siesta like DM. However, unlike DM, flies continue to sleep beyond siesta till the evening. DA has a less prominent siesta compared to DM and DMK. In the morning, DA took a longer time to respond to the lights ON and continued to sleep for at least half an hour. The nighttime sleep of the DA flies is higher than the other two species. Average length of sleep episode is three times more than that of DM and DMK with few wake episodes. Thus, the nighttime sleep of DA males and females is deep and needs exposure to more potent stimuli to wake up relative to the other two species. DA males and females show higher sleep rebound than the other two species, suggesting the robustness of sleep homeostasis. Although total sleep of DMK and DA is similar, DA is a day-active species with highly consolidated night sleep. DMK, like DM, is a crepuscular species with a midday siesta. Thus, our results suggest that temporal partitioning of sleep, in sympatric species may contribute to temporal segregation.
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Affiliation(s)
- Sukriti Mishra
- Department of Zoology, Central University of Punjab, Bathinda, Punjab, 151001, India
| | - Nisha Sharma
- Department of Zoology, Central University of Punjab, Bathinda, Punjab, 151001, India
| | - Sunil Kumar Singh
- Department of Zoology, Central University of Punjab, Bathinda, Punjab, 151001, India
| | - Shahnaz Rahman Lone
- Department of Zoology, Central University of Punjab, Bathinda, Punjab, 151001, India.
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10
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Lee H, Lim C. Circadian gating of light-induced arousal in Drosophila sleep. J Neurogenet 2022:1-11. [DOI: 10.1080/01677063.2022.2151596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Affiliation(s)
- Hoyeon Lee
- Department of Biological Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
| | - Chunghun Lim
- Department of Biological Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
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11
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Light triggers a network switch between circadian morning and evening oscillators controlling behaviour during daily temperature cycles. PLoS Genet 2022; 18:e1010487. [PMID: 36367867 PMCID: PMC9683589 DOI: 10.1371/journal.pgen.1010487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 11/23/2022] [Accepted: 10/20/2022] [Indexed: 11/13/2022] Open
Abstract
Proper timing of rhythmic locomotor behavior is the consequence of integrating environmental conditions and internal time dictated by the circadian clock. Rhythmic environmental input like daily light and temperature changes (called Zeitgeber) reset the molecular clock and entrain it to the environmental time zone the organism lives in. Furthermore, depending on the absolute temperature or light intensity, flies exhibit their main locomotor activity at different times of day, i.e., environmental input not only entrains the circadian clock but also determines the phase of a certain behavior. To understand how the brain clock can distinguish between (or integrate) an entraining Zeitgeber and environmental effects on activity phase, we attempted to entrain the clock with a Zeitgeber different from the environmental input used for phasing the behavior. 150 clock neurons in the Drosophila melanogaster brain control different aspects of the daily activity rhythms and are organized in various clusters. During regular 12 h light: 12 h dark cycles at constant mild temperature (LD 25°C, LD being the Zeitgeber), so called morning oscillator (MO) neurons control the increase of locomotor activity just before lights-on, while evening oscillator (EO) neurons regulate the activity increase at the end of the day, a few hours before lights-off. Here, using 12 h: 12 h 25°C:16°C temperature cycles as Zeitgeber, we attempted to look at the impact of light on phasing locomotor behavior. While in constant light and 25°C:16°C temperature cycles (LLTC), flies show an unimodal locomotor activity peak in the evening, during the same temperature cycle, but in the absence of light (DDTC), the phase of the activity peak is shifted to the morning. Here, we show that the EO is necessary for synchronized behavior in LLTC but not for entraining the molecular clock of the other clock neuronal groups, while the MO controls synchronized morning activity in DDTC. Interestingly, our data suggest that the influence of the EO on the synchronization increases depending on the length of the photoperiod (constant light vs 12 h of light). Hence, our results show that effects of different environmental cues on clock entrainment and activity phase can be separated, allowing to decipher their integration by the circadian clock. “If a clock is to provide information involved in controlling important functions, then clearly it must be reasonably reliable” said Colin Pittendrigh, one of the chronobiology pioneers in 1954. The circadian clock allows organisms to synchronize with their ecological niche. For this, the circadian clock uses rhythmic environmental parameters (Zeitgeber), the main ones being light and temperature. Hence, Colin Pittendrigh posted a still unresolved enigma in chronobiology. How can a clock be reliable when its resetting depends on environmental fluctuations that are not so reliable? Both, light and temperature vary a lot on a day-to-day basis, and animals respond to these variations depending on the time of day. Here, we propose a new model where the molecular clock resets to environmental cycles in a robust and independent manner, while the underlying neuronal oscillatory network switches its balance towards specific oscillators depending on the environmental condition thereby leading to distinct behavioral adaptation. To proof this proposed dogma in fruit flies, using temperature cycles as Zeitgeber, we demonstrate a light-induced switch of the network balance. Hence, we supply a foundation that in the future will help to understand how animals use their circadian clock to adapt their behavior to environmental changes.
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12
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Circuit analysis reveals a neural pathway for light avoidance in Drosophila larvae. Nat Commun 2022; 13:5274. [PMID: 36071059 PMCID: PMC9452580 DOI: 10.1038/s41467-022-33059-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 08/31/2022] [Indexed: 11/30/2022] Open
Abstract
Understanding how neural circuits underlie behaviour is challenging even in the connectome era because it requires a combination of anatomical and functional analyses. This is exemplified in the circuit underlying the light avoidance behaviour displayed by Drosophila melanogaster larvae. While this behaviour is robust and the nervous system relatively simple, the circuit is only partially delineated with some contradictions among studies. Here, we devise trans-Tango MkII, an offshoot of the transsynaptic circuit tracing tool trans-Tango, and implement it in anatomical tracing together with functional analysis. We use neuronal inhibition to test necessity of particular neuronal types in light avoidance and selective neuronal activation to examine sufficiency in rescuing light avoidance deficiencies exhibited by photoreceptor mutants. Our studies reveal a four-order circuit for light avoidance connecting the light-detecting photoreceptors with a pair of neuroendocrine cells via two types of clock neurons. This approach can be readily expanded to studying other circuits. Studying neural circuits requires a multipronged approach. Here, the authors present a transsynaptic tracing tool in fruit fly larvae and combine it with neuronal inhibition and activation to study the circuit underlying light avoidance behaviour.
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13
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The Effects of Artificial Night Lighting on Tail Regeneration and Prey Consumption in a Nocturnal Salamander (Plethodon cinereus) and on the Behavior of Fruit Fly Prey (Drosophila virilis). Animals (Basel) 2022; 12:ani12162105. [PMID: 36009695 PMCID: PMC9405242 DOI: 10.3390/ani12162105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 08/11/2022] [Accepted: 08/12/2022] [Indexed: 11/17/2022] Open
Abstract
Simple Summary Amphibians, including salamanders, are declining worldwide at an alarming rate due to a variety of factors that include habitat decline and destruction and environmental pollutants. Artificial light at night (ALAN) due to human activities is a nearly ubiquitous pollutant and can have serious consequences for amphibians. We examined the impact of ecologically-relevant levels of ALAN on tail regeneration in the eastern red-backed salamander, prey consumption by these salamanders and behavior of their fruit fly prey. We found that ALAN reduced the rate of salamander tail regeneration at some light levels above the naturally dark nocturnal illumination and increased the activity of their prey but not always in a simple, linear fashion. Thus, ALAN, even at very low levels, can influence the physiology and regeneration of a nocturnal salamander. Abstract As human development continues to encroach into natural habitats, artificial light at night (ALAN) has increasingly become a concern for wildlife. Nocturnal animals are especially vulnerable to ALAN, as the physiology and behavior of nocturnal species have evolved under conditions associated with predictably dark environments. Studies exposing amphibians to constant bright light provide evidence for changes to normal metabolism, growth, and behavior, but few of these studies have used treatments of dim ALAN comparable to that found in affected habitats. Eastern red-backed salamanders, Plethodon cinereus, use their tails for fat storage and communication, are capable of tail autotomy as an antipredator mechanism, and can regenerate the tail in its entirety. We examined the effect of different, ecologically-relevant intensities of ALAN on the rate of tail regeneration in adult P. cinereus. We hypothesized that ALAN would increase tail regeneration rates such that salamanders exposed to higher levels of light at night would regenerate tails faster than those exposed to lower light levels. In a controlled laboratory setting, we exposed salamanders (N = 76) in test chambers to nocturnal illuminations of 0.0001 lx (no ALAN, natural nocturnal illumination dark control), 0.01 lx (weak ALAN), 1 lx (moderate ALAN), or 100 lx (bright ALAN, equal to dim daytime and our day lighting treatment) for a period of 90 d immediately following tail autotomy. In addition, because these salamanders eat mostly live, moving prey, we investigated the impact of ALAN on the behavior of prey (Drosophila virilis) fed to the salamanders in our laboratory trials, which could alter feeding and regeneration rates in salamanders. We predicted that prey consumption would not be affected by ALAN and measured both prey consumption and prey behavior (activity) to examine the potential influence on regeneration. For tail regeneration, we found a non-monotonic response to ALAN, with salamanders exposed to nocturnal illuminations 0.1 lx and 100 lx regenerating tails significantly slower than salamanders in the 0.0001 lx or 1 lx treatments. Prey consumption did not differ among light treatments; however, fruit fly activity increased with increasing ALAN. These results suggest that ALAN influences regeneration rates, but the rate of regeneration is not dose-dependent and is not explained easily by prey consumption or movement of prey. We suggest that tail regeneration in these salamanders may involve a complex mechanism of altered gene expression and/or modulation of hormonal activity (corticosterone, melatonin, serotonin, and/or prolactin) at different intensities of nocturnal lighting.
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The regulation of circadian rhythm by insulin signaling in Drosophila. Neurosci Res 2022; 183:76-83. [PMID: 35872183 DOI: 10.1016/j.neures.2022.07.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 07/11/2022] [Accepted: 07/19/2022] [Indexed: 11/23/2022]
Abstract
Circadian rhythm is well conserved across species and relates to numerous biological functions. Circadian misalignment impairs metabolic function. Insulin signaling is a key modulator of metabolism in the fruit fly as well as mammals and its defects cause metabolic disease. Daily diet timing affects both circadian rhythmicities of behavior and metabolism. However, the relationship between the circadian clock and insulin signaling is still elusive. Here, we report that insulin signaling regulates circadian rhythm in Drosophila melanogaster. We found the insulin receptor substrate mutant, chico1, showed a shorter free-running circadian period. The knockdown of insulin receptor (InR), or another signaling molecule downstream of InR, dp110, or the expression of a dominant-negative form of InR resulted in the shortening of the circadian period and diminished its amplitude. The impairment of insulin signaling both in all neurons and restricted circadian clock neurons altered circadian period length, indicating that the insulin signaling plays a role in the regulation of circadian rhythm in clock cells. Among 3 insulin-like ligands expressed in the brain, dilp5 showed the largest effect on circadian phenotype when deleted. These results suggested that insulin signaling contributes to the robustness of the circadian oscillation and coordinates metabolism and behavior.
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15
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Meiselman MR, Alpert MH, Cui X, Shea J, Gregg I, Gallio M, Yapici N. Recovery from cold-induced reproductive dormancy is regulated by temperature-dependent AstC signaling. Curr Biol 2022; 32:1362-1375.e8. [PMID: 35176227 PMCID: PMC8969192 DOI: 10.1016/j.cub.2022.01.061] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 12/09/2021] [Accepted: 01/21/2022] [Indexed: 11/25/2022]
Abstract
Animals have evolved a variety of behaviors to cope with adverse environmental conditions. Similar to other insects, the fly, Drosophila melanogaster, responds to sustained cold by reducing its metabolic rate and arresting its reproduction. Here, we show that a subset of dorsal neurons (DN3s) that express the neuropeptide allatostatin C (AstC) facilitates recovery from cold-induced reproductive dormancy. The activity of AstC-expressing DN3s, as well as AstC peptide levels, are suppressed by cold. Cold temperature also impacts AstC levels in other Drosophila species and mosquitoes, Aedes aegypti, and Anopheles stephensi. The stimulatory effect of AstC on egg production is mediated by cholinergic AstC-R2 neurons. Our results demonstrate that DN3s coordinate female reproductive capacity with environmental temperature via AstC signaling. AstC/AstC-R2 is conserved across many insect species and their role in regulating female reproductive capacity makes them an ideal target for controlling the population of agricultural pests and human disease vectors.
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Affiliation(s)
- Matthew R Meiselman
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
| | - Michael H Alpert
- Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA
| | - Xinyue Cui
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
| | - Jamien Shea
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
| | - Ian Gregg
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
| | - Marco Gallio
- Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA
| | - Nilay Yapici
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA.
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16
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Eick AK, Ogueta M, Buhl E, Hodge JJL, Stanewsky R. The opposing chloride cotransporters KCC and NKCC control locomotor activity in constant light and during long days. Curr Biol 2022; 32:1420-1428.e4. [PMID: 35303416 DOI: 10.1016/j.cub.2022.01.056] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 12/06/2021] [Accepted: 01/20/2022] [Indexed: 01/08/2023]
Abstract
Cation chloride cotransporters (CCCs) regulate intracellular chloride ion concentration ([Cl-]i) within neurons, which can reverse the direction of the neuronal response to the neurotransmitter GABA.1 Na+ K+ Cl- (NKCC) and K+ Cl- (KCC) cotransporters transport Cl- into or out of the cell, respectively. When NKCC activity dominates, the resulting high [Cl-]i can lead to an excitatory and depolarizing response of the neuron upon GABAA receptor opening, while KCC dominance has the opposite effect.1 This inhibitory-to-excitatory GABA switch has been linked to seasonal adaption of circadian clock function to changing day length,2-4 and its dysregulation is associated with neurodevelopmental disorders such as epilepsy.5-8 In Drosophila melanogaster, constant light normally disrupts circadian clock function and leads to arrhythmic behavior.9 Here, we demonstrate a function for CCCs in regulating Drosophila locomotor activity and GABA responses in circadian clock neurons because alteration of CCC expression in circadian clock neurons elicits rhythmic behavior in constant light. We observed the same effects after downregulation of the Wnk and Fray kinases, which modulate CCC activity in a [Cl-]i-dependent manner. Patch-clamp recordings from the large LNv clock neurons show that downregulation of KCC results in a more positive GABA reversal potential, while KCC overexpression has the opposite effect. Finally, KCC and NKCC downregulation reduces or increases morning behavioral activity during long photoperiods, respectively. In summary, our results support a model in which the regulation of [Cl-]i by a KCC/NKCC/Wnk/Fray feedback loop determines the response of clock neurons to GABA, which is important for adjusting behavioral activity to constant light and long-day conditions.
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Affiliation(s)
- Anna Katharina Eick
- Institute of Neuro- and Behavioral Biology, Westfälische Wilhelms University, 48149 Münster, Germany
| | - Maite Ogueta
- Institute of Neuro- and Behavioral Biology, Westfälische Wilhelms University, 48149 Münster, Germany
| | - Edgar Buhl
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol BS8 1TD, UK
| | - James J L Hodge
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol BS8 1TD, UK
| | - Ralf Stanewsky
- Institute of Neuro- and Behavioral Biology, Westfälische Wilhelms University, 48149 Münster, Germany.
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17
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Deppisch P, Prutscher JM, Pegoraro M, Tauber E, Wegener C, Helfrich-Förster C. Adaptation of Drosophila melanogaster to Long Photoperiods of High-Latitude Summers Is Facilitated by the ls-Timeless Allele. J Biol Rhythms 2022; 37:185-201. [PMID: 35301885 PMCID: PMC9008550 DOI: 10.1177/07487304221082448] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Circadian clocks help animals to be active at the optimal time of the day whereby for most species the daily light-dark cycle is the most important zeitgeber for their circadian clock. In this respect, long arctic summer days are particularly challenging as light is present almost 24 h per day, and continuous light makes the circadian clocks of many animals arrhythmic. This is especially true for the fruit fly, Drosophila melanogaster, which possesses a very light-sensitive clock. The blue-light photoreceptor Cryptochrome (CRY) and the clock protein Timeless (TIM) are the light-sensitive components of the circadian clock and are responsible for constant light-induced arrhythmicity even at very low light intensities. Nevertheless, D. melanogaster was able to spread from its tropical origin and invade northern latitudes. Here, we tested whether a natural polymorphism at the timeless (tim) locus, s-tim and ls-tim, helped adaptation to very long photoperiods. The recently evolved natural allele, ls-tim, encodes a longer, less light sensitive form of TIM (L-TIM) in addition to the shorter (S-TIM) form, the only form encoded by the ancient s-tim allele. ls-tim has evolved in southeastern Italy and slowly spreads to higher latitudes. L-TIM is known to interact less efficiently with CRY as compared with S-TIM. Here, we studied the locomotor activity patterns of ~40 wild s-tim and ls-tim isofemale lines caught at different latitudes under simulated high-latitude summer light conditions (continuous light or long photoperiods with 20-h daily light). We found that the ls-tim lines were significantly more rhythmic under continuous light than the s-tim lines. Importantly, the ls-tim lines can delay their evening activity under long photoperiods, a behavioral adaptation that appears to be optimal under high-latitude conditions. Our observations suggest that the functional gain associated with ls-tim may drive the northern spread of this allele by directional selection.
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Affiliation(s)
- Peter Deppisch
- Neurobiology and Genetics, Theodor-Boveri Institute, Biocenter, Julius-Maximilians-University of Würzburg, Würzburg, Germany
| | - Johanna M Prutscher
- Neurobiology and Genetics, Theodor-Boveri Institute, Biocenter, Julius-Maximilians-University of Würzburg, Würzburg, Germany
| | - Mirko Pegoraro
- Faculty of Science, School of Biological and Environmental Science, Liverpool John Moores University, Liverpool, UK
| | - Eran Tauber
- Department of Evolutionary and Environmental Biology, Institute of Evolution, University of Haifa, Haifa, Israel
| | - Christian Wegener
- Neurobiology and Genetics, Theodor-Boveri Institute, Biocenter, Julius-Maximilians-University of Würzburg, Würzburg, Germany
| | - Charlotte Helfrich-Förster
- Neurobiology and Genetics, Theodor-Boveri Institute, Biocenter, Julius-Maximilians-University of Würzburg, Würzburg, Germany
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Hoikkala A, Poikela N. Adaptation and ecological speciation in seasonally varying environments at high latitudes: Drosophila virilis group. Fly (Austin) 2022; 16:85-104. [PMID: 35060806 PMCID: PMC8786326 DOI: 10.1080/19336934.2021.2016327] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Living in high latitudes and altitudes sets specific requirements on species’ ability to forecast seasonal changes and to respond to them in an appropriate way. Adaptation into diverse environmental conditions can also lead to ecological speciation through habitat isolation or by inducing changes in traits that influence assortative mating. In this review, we explain how the unique time-measuring systems of Drosophila virilis group species have enabled the species to occupy high latitudes and how the traits involved in species reproduction and survival exhibit strong linkage with latitudinally varying photoperiodic and climatic conditions. We also describe variation in reproductive barriers between the populations of two species with overlapping distributions and show how local adaptation and the reinforcement of prezygotic barriers have created partial reproductive isolation between conspecific populations. Finally, we consider the role of species-specific chromosomal inversions and the X chromosome in the development of reproductive barriers between diverging lineages.
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Affiliation(s)
- Anneli Hoikkala
- Department of Biological and Environmental Sciences, University of Jyväskylä, Jyväskylä, Finland
| | - Noora Poikela
- Department of Biological and Environmental Sciences, University of Jyväskylä, Jyväskylä, Finland
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19
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Yamaguchi ST, Tomita J, Kume K. Insulin signaling in clock neurons regulates sleep in Drosophila. Biochem Biophys Res Commun 2021; 591:44-49. [PMID: 34998032 DOI: 10.1016/j.bbrc.2021.12.100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 12/26/2021] [Indexed: 12/12/2022]
Abstract
Sleep relates to numerous biological functions, including metabolism. Both dietary conditions and genes related to metabolism are known to affect sleep behavior. Insulin signaling is well conserved across species including the fruit fly and relates to both metabolism and sleep. However, the neural mechanism of sleep regulation by insulin signaling is poorly understood. Here, we report that insulin signaling in specific neurons regulates sleep in Drosophila melanogaster. We analyzed the sleep behavior of flies with the mutation in insulin-like ligands expressed in the brain and found that three insulin-like ligands participate in sleep regulation with some redundancy. We next used 21 Gal4 drivers to express a dominant-negative form of the insulin receptor (InR DN) in various neurons including circadian clock neurons, which express the clock gene, and the pars intercerebralis (PI). Inhibition of insulin signaling in the anterior dorsal neuron group 1 (DN1a) decreased sleep. Additionally, the same manipulation in PI also decreased sleep. Pan-neuronal induced expression of InR DN also decreased sleep. These results suggested that insulin signaling in DN1a and PI regulates sleep.
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Affiliation(s)
- Sho T Yamaguchi
- Department of Neuropharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, 467-8603, Japan.
| | - Jun Tomita
- Department of Neuropharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, 467-8603, Japan.
| | - Kazuhiko Kume
- Department of Neuropharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, 467-8603, Japan.
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Ramakrishnan A, Sheeba V. Gap junction protein Innexin2 modulates the period of free-running rhythms in Drosophila melanogaster. iScience 2021; 24:103011. [PMID: 34522854 PMCID: PMC8426565 DOI: 10.1016/j.isci.2021.103011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/13/2021] [Accepted: 08/17/2021] [Indexed: 10/25/2022] Open
Abstract
A neuronal circuit of ∼150 neurons modulates rhythmic activity-rest behavior of Drosophila melanogaster. While it is known that coherent ∼24-hr rhythms in locomotion are brought about when 7 distinct neuronal clusters function as a network due to chemical communication amongst them, there are no reports of communication via electrical synapses made up of gap junctions. Here, we report that gap junction proteins, Innexins play crucial roles in determining the intrinsic period of activity-rest rhythms in flies. We show the presence of Innexin2 in the ventral lateral neurons, wherein RNAi-based knockdown of its expression slows down the speed of activity-rest rhythm along with alterations in the oscillation of a core-clock protein PERIOD and the output molecule pigment dispersing factor. Specifically disrupting the channel-forming ability of Innexin2 causes period lengthening, suggesting that Innexin2 may function as hemichannels or gap junctions in the clock circuit.
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Affiliation(s)
- Aishwarya Ramakrishnan
- Chronobiology and Behavioural Neurogenetics Laboratory, Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, Karnataka 560064, India
| | - Vasu Sheeba
- Chronobiology and Behavioural Neurogenetics Laboratory, Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, Karnataka 560064, India
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21
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Drosophila clock cells use multiple mechanisms to transmit time-of-day signals in the brain. Proc Natl Acad Sci U S A 2021; 118:2019826118. [PMID: 33658368 DOI: 10.1073/pnas.2019826118] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Regulation of circadian behavior and physiology by the Drosophila brain clock requires communication from central clock neurons to downstream output regions, but the mechanism by which clock cells regulate downstream targets is not known. We show here that the pars intercerebralis (PI), previously identified as a target of the morning cells in the clock network, also receives input from evening cells. We determined that morning and evening clock neurons have time-of-day-dependent connectivity to the PI, which is regulated by specific peptides as well as by fast neurotransmitters. Interestingly, PI cells that secrete the peptide DH44, and control rest:activity rhythms, are inhibited by clock inputs while insulin-producing cells (IPCs) are activated, indicating that the same clock cells can use different mechanisms to drive cycling in output neurons. Inputs of morning cells to IPCs are relevant for the circadian rhythm of feeding, reinforcing the role of the PI as a circadian relay that controls multiple behavioral outputs. Our findings provide mechanisms by which clock neurons signal to nonclock cells to drive rhythms of behavior.
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22
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Lankinen P, Kastally C, Hoikkala A. Nanda-Hamner Curves Show Huge Latitudinal Variation but No Circadian Components in Drosophila Montana Photoperiodism. J Biol Rhythms 2021; 36:226-238. [PMID: 33745359 PMCID: PMC8114436 DOI: 10.1177/0748730421997265] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Insect species with a wide distribution offer a great opportunity to trace latitudinal variation in the photoperiodic regulation of traits important in reproduction and stress tolerances. We measured this variation in the photoperiodic time-measuring system underlying reproductive diapause in Drosophila montana, using a Nanda-Hamner (NH) protocol. None of the study strains showed diel rhythmicity in female diapause proportions under a constant day length (12 h) and varying night lengths in photoperiods ranging from 16 to 84 h at 16°C. In the northernmost strains (above 55°N), nearly all females entered diapause under all photoperiods and about half of them even in continuous darkness, while the females of the southern strains showed high diapause proportions only in the circadian 24 h photoperiod. Significant correlation between the strains' mean diapause proportions in ≥ 24 h photoperiods and critical day length (CDL; half of the females enter diapause) suggests at least partial causal connection between the traits. Interestingly, females of the northern strains entered diapause even in ≤ 24 h photoperiods, where the night length was shorter than their critical night length (24 h - CDL), but where the females experienced a higher number of Light:Dark cycles than in 24 h photoperiods. NH experiments, performed on the control and selection lines in our previous selection experiment, and completed here, gave similar results and confirmed that selection for shorter, southern-type CDL decreases female diapausing rate in non-circadian photoperiods. Overall, our study shows that D. montana females measure night length quantitatively, that the photoperiodic counter may play a prominent but slightly different role in extra short and extra long photoperiods and that northern strains show high stability against perturbations in the photoperiod length and in the presence of LD cycles. These features are best explained by the quantitative versions of the damped external coincidence model.
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Affiliation(s)
- Pekka Lankinen
- Department of Ecology and Genetics, University of Oulu, Oulu, Finland
| | - Chedly Kastally
- Department of Ecology and Genetics, University of Oulu, Oulu, Finland
| | - Anneli Hoikkala
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
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Jaumouillé E, Koch R, Nagoshi E. Uncovering the Roles of Clocks and Neural Transmission in the Resilience of Drosophila Circadian Network. Front Physiol 2021; 12:663339. [PMID: 34122135 PMCID: PMC8188733 DOI: 10.3389/fphys.2021.663339] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 05/03/2021] [Indexed: 11/22/2022] Open
Abstract
Studies of circadian locomotor rhythms in Drosophila melanogaster gave evidence to the preceding theoretical predictions on circadian rhythms. The molecular oscillator in flies, as in virtually all organisms, operates using transcriptional-translational feedback loops together with intricate post-transcriptional processes. Approximately150 pacemaker neurons, each equipped with a molecular oscillator, form a circuit that functions as the central pacemaker for locomotor rhythms. Input and output pathways to and from the pacemaker circuit are dissected to the level of individual neurons. Pacemaker neurons consist of functionally diverse subclasses, including those designated as the Morning/Master (M)-oscillator essential for driving free-running locomotor rhythms in constant darkness and the Evening (E)-oscillator that drives evening activity. However, accumulating evidence challenges this dual-oscillator model for the circadian circuit organization and propose the view that multiple oscillators are coordinated through network interactions. Here we attempt to provide further evidence to the revised model of the circadian network. We demonstrate that the disruption of molecular clocks or neural output of the M-oscillator during adulthood dampens free-running behavior surprisingly slowly, whereas the disruption of both functions results in an immediate arrhythmia. Therefore, clocks and neural communication of the M-oscillator act additively to sustain rhythmic locomotor output. This phenomenon also suggests that M-oscillator can be a pacemaker or a downstream path that passively receives rhythmic inputs from another pacemaker and convey output signals. Our results support the distributed network model and highlight the remarkable resilience of the Drosophila circadian pacemaker circuit, which can alter its topology to maintain locomotor rhythms.
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Affiliation(s)
| | | | - Emi Nagoshi
- Department of Genetics and Evolution, Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva, Switzerland
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Beer K, Helfrich-Förster C. Model and Non-model Insects in Chronobiology. Front Behav Neurosci 2020; 14:601676. [PMID: 33328925 PMCID: PMC7732648 DOI: 10.3389/fnbeh.2020.601676] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 10/30/2020] [Indexed: 12/20/2022] Open
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.
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Affiliation(s)
- Katharina Beer
- Neurobiology and Genetics, Theodor-Boveri Institute, Biocentre, Am Hubland, University of Würzburg, Würzburg, Germany
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Cobb T, Sujkowski A, Morton C, Ramesh D, Wessells R. Variation in mobility and exercise adaptations between Drosophila species. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2020; 206:611-621. [PMID: 32335730 PMCID: PMC7314734 DOI: 10.1007/s00359-020-01421-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 04/08/2020] [Accepted: 04/15/2020] [Indexed: 12/30/2022]
Abstract
Locomotion and mobility have been studied extensively in Drosophila melanogaster but less is known about the locomotor capacity of other Drosophila species, while the response to chronic exercise in other species has yet to be examined. We have shown that adult male D. melanogaster adapt to exercise training with improved running endurance, climbing speed, and flight ability compared to unexercised flies. Here, we examine baseline mobility of D. sechellia, D. simulans, and D. virilis, and their response to chronic exercise training. We found significant interspecific differences in mobility and in the response to exercise. Although there is a significant sex difference in exercise adaptations in D. melanogaster, intraspecific analysis reveals few sex differences in other Drosophila species. As octopamine has been shown to be important for exercise adaptations in D. melanogaster, we also asked if any observed differences could be attributed to baseline octopamine levels. We find that octopamine and tyramine levels have the same rank order as baseline climbing speed and endurance in males, but do not predict the response to chronic exercise in males or females. Future research should focus on determining the mechanisms responsible for the inter- and intraspecific differences in mobility and the response to exercise.
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Affiliation(s)
- Tyler Cobb
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Alyson Sujkowski
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Courtney Morton
- Department of Kinesiology, Wayne State University, Detroit, MI, 48201, USA
| | - Divya Ramesh
- Department of Biology, University of Konstanz, 78464, Konstanz, Baden Württemberg, Germany
| | - Robert Wessells
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48201, USA.
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Nair S, Bahn JH, Lee G, Yoo S, Park JH. A Homeobox Transcription Factor Scarecrow (SCRO) Negatively Regulates Pdf Neuropeptide Expression through Binding an Identified cis-Acting Element in Drosophila melanogaster. Mol Neurobiol 2020; 57:2115-2130. [DOI: 10.1007/s12035-020-01874-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2019] [Accepted: 01/09/2020] [Indexed: 12/17/2022]
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Helfrich‐Förster C, Bertolini E, Menegazzi P. Flies as models for circadian clock adaptation to environmental challenges. Eur J Neurosci 2020; 51:166-181. [PMID: 30269385 PMCID: PMC7027873 DOI: 10.1111/ejn.14180] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 08/14/2018] [Accepted: 08/17/2018] [Indexed: 01/02/2023]
Abstract
Life on earth is assumed to have developed in tropical regions that are characterized by regular 24 hr cycles in irradiance and temperature that remain the same throughout the seasons. All organisms developed circadian clocks that predict these environmental cycles and prepare the organisms in advance for them. A central question in chronobiology is how endogenous clocks changed in order to anticipate very different cyclical environmental conditions such as extremely short and long photoperiods existing close to the poles. Flies of the family Drosophilidae can be found all over the world-from the tropics to subarctic regions-making them unprecedented models for studying the evolutionary processes that underlie the adaptation of circadian clocks to different latitudes. This review summarizes our current understanding of these processes. We discuss evolutionary changes in the clock genes and in the clock network in the brain of different Drosophilids that may have caused behavioural adaptations to high latitudes.
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Affiliation(s)
| | - Enrico Bertolini
- Neurobiology and GeneticsTheodor‐Boveri InstituteBiocentre, University of WürzburgWürzburgGermany
| | - Pamela Menegazzi
- Neurobiology and GeneticsTheodor‐Boveri InstituteBiocentre, University of WürzburgWürzburgGermany
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Chen M, Talarovicova A, Zheng Y, Storey KB, Elphick MR. Neuropeptide precursors and neuropeptides in the sea cucumber Apostichopus japonicus: a genomic, transcriptomic and proteomic analysis. Sci Rep 2019; 9:8829. [PMID: 31222106 PMCID: PMC6586643 DOI: 10.1038/s41598-019-45271-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 06/04/2019] [Indexed: 02/07/2023] Open
Abstract
The sea cucumber Apostichopus japonicus is a foodstuff with very high economic value in China, Japan and other countries in south-east Asia. It is at the heart of a multibillion-dollar industry and to meet demand for this product, aquaculture methods and facilities have been established. However, there are challenges associated with optimization of reproduction, feeding and growth in non-natural environments. Therefore, we need to learn more about the biology of A. japonicus, including processes such as aestivation, evisceration, regeneration and albinism. One of the major classes of molecules that regulate physiology and behaviour in animals are neuropeptides, and a few bioactive peptides have already been identified in A. japonicus. To facilitate more comprehensive investigations of neuropeptide function in A. japonicus, here we have analysed genomic and transcriptomic sequence data and proteomic data to identify neuropeptide precursors and neuropeptides in this species. We identified 44 transcripts encoding neuropeptide precursors or putative neuropeptide precursors, and in some instances neuropeptides derived from these precursors were confirmed by mass spectrometry. Furthermore, analysis of genomic sequence data enabled identification of the location of neuropeptide precursor genes on genomic scaffolds and linkage groups (chromosomes) and determination of gene structure. Many of the precursors identified contain homologs of neuropeptides that have been identified in other bilaterian animals. Precursors of neuropeptides that have thus far only been identified in echinoderms were identified, including L- and F-type SALMFamides, AN peptides and others. Precursors of several peptides that act as modulators of neuromuscular activity in A. japonicus were also identified. The discovery of a large repertoire of neuropeptide precursors and neuropeptides provides a basis for experimental studies that investigate the physiological roles of neuropeptide signaling systems in A. japonicus. Looking ahead, some of these neuropeptides may have effects that could be harnessed to enable improvements in the aquaculture of this economically important species.
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Affiliation(s)
- Muyan Chen
- The Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, PR, China.
| | - Alzbeta Talarovicova
- School of Biological & Chemical Sciences, Queen Mary University of London, London, E1 4NS, UK
| | - Yingqiu Zheng
- The Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, PR, China
| | - Kenneth B Storey
- Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Maurice R Elphick
- School of Biological & Chemical Sciences, Queen Mary University of London, London, E1 4NS, UK.
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29
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Nagy D, Cusumano P, Andreatta G, Anduaga AM, Hermann-Luibl C, Reinhard N, Gesto J, Wegener C, Mazzotta G, Rosato E, Kyriacou CP, Helfrich-Förster C, Costa R. Peptidergic signaling from clock neurons regulates reproductive dormancy in Drosophila melanogaster. PLoS Genet 2019; 15:e1008158. [PMID: 31194738 PMCID: PMC6592559 DOI: 10.1371/journal.pgen.1008158] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Revised: 06/25/2019] [Accepted: 04/25/2019] [Indexed: 11/18/2022] Open
Abstract
With the approach of winter, many insects switch to an alternative protective developmental program called diapause. Drosophila melanogaster females overwinter as adults by inducing a reproductive arrest that is characterized by inhibition of ovarian development at previtellogenic stages. The insulin producing cells (IPCs) are key regulators of this process, since they produce and release insulin-like peptides that act as diapause-antagonizing hormones. Here we show that in D. melanogaster two neuropeptides, Pigment Dispersing Factor (PDF) and short Neuropeptide F (sNPF) inhibit reproductive arrest, likely through modulation of the IPCs. In particular, genetic manipulations of the PDF-expressing neurons, which include the sNPF-producing small ventral Lateral Neurons (s-LNvs), modulated the levels of reproductive dormancy, suggesting the involvement of both neuropeptides. We expressed a genetically encoded cAMP sensor in the IPCs and challenged brain explants with synthetic PDF and sNPF. Bath applications of both neuropeptides increased cAMP levels in the IPCs, even more so when they were applied together, suggesting a synergistic effect. Bath application of sNPF additionally increased Ca2+ levels in the IPCs. Our results indicate that PDF and sNPF inhibit reproductive dormancy by maintaining the IPCs in an active state.
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Affiliation(s)
- Dóra Nagy
- Department of Biology, University of Padova, Padova, Italy
| | - Paola Cusumano
- Department of Biology, University of Padova, Padova, Italy
| | | | - Ane Martin Anduaga
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Christiane Hermann-Luibl
- Neurobiology and Genetics, Theodor-Boveri-Institute, Biocenter, University of Würzburg, Würzburg, Germany
| | - Nils Reinhard
- Neurobiology and Genetics, Theodor-Boveri-Institute, Biocenter, University of Würzburg, Würzburg, Germany
| | - João Gesto
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Christian Wegener
- Neurobiology and Genetics, Theodor-Boveri-Institute, Biocenter, University of Würzburg, Würzburg, Germany
| | | | - Ezio Rosato
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Charalambos P. Kyriacou
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Charlotte Helfrich-Förster
- Neurobiology and Genetics, Theodor-Boveri-Institute, Biocenter, University of Würzburg, Würzburg, Germany
| | - Rodolfo Costa
- Department of Biology, University of Padova, Padova, Italy
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30
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Bulthuis N, Spontak KR, Kleeman B, Cavanaugh DJ. Neuronal Activity in Non-LNv Clock Cells Is Required to Produce Free-Running Rest:Activity Rhythms in Drosophila. J Biol Rhythms 2019; 34:249-271. [PMID: 30994046 DOI: 10.1177/0748730419841468] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Circadian rhythms in behavior and physiology are produced by central brain clock neurons that can be divided into subpopulations based on molecular and functional characteristics. It has become clear that coherent behavioral rhythms result from the coordinated action of these clock neuron populations, but many questions remain regarding the organizational logic of the clock network. Here we used targeted genetic tools in Drosophila to eliminate either molecular clock function or neuronal activity in discrete clock neuron subsets. We find that neuronal firing is necessary across multiple clock cell populations to produce free-running rhythms of rest and activity. In contrast, such rhythms are much more subtly affected by molecular clock suppression in the same cells. These findings demonstrate that network connectivity can compensate for a lack of molecular oscillations within subsets of clock cells. We further show that small ventrolateral (sLNv) clock neurons, which have been characterized as master pacemakers under free-running conditions, cannot drive rhythms independent of communication between other cells of the clock network. In particular, we pinpoint an essential contribution of the dorsolateral (LNd) clock neurons, and show that manipulations that affect LNd function reduce circadian rhythm strength without affecting molecular cycling in sLNv cells. These results suggest a hierarchical organization in which circadian information is first consolidated among one or more clock cell populations before accessing output pathways that control locomotor activity.
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31
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Díaz MM, Schlichting M, Abruzzi KC, Long X, Rosbash M. Allatostatin-C/AstC-R2 Is a Novel Pathway to Modulate the Circadian Activity Pattern in Drosophila. Curr Biol 2018; 29:13-22.e3. [PMID: 30554904 PMCID: PMC6325008 DOI: 10.1016/j.cub.2018.11.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 09/25/2018] [Accepted: 11/01/2018] [Indexed: 02/08/2023]
Abstract
Seven neuropeptides are expressed within the Drosophila brain circadian network. Our previous mRNA profiling suggested that Allatostatin-C (AstC) is an eighth neuropeptide and specifically expressed in dorsal clock neurons (DN1s). Our results here show that AstC is, indeed, expressed in DN1s, where it oscillates. AstC is also expressed in two less well-characterized circadian neuronal clusters, the DN3s and lateral-posterior neurons (LPNs). Behavioral experiments indicate that clock-neuron-derived AstC is required to mediate evening locomotor activity under short (winter-like) and long (summer-like) photoperiods. The AstC-Receptor 2 (AstC-R2) is expressed in LNds, the clock neurons that drive evening locomotor activity, and AstC-R2 is required in these neurons to modulate the same short photoperiod evening phenotype. Ex vivo calcium imaging indicates that AstC directly inhibits a single LNd. The results suggest that a novel AstC/AstC-R2 signaling pathway, from dorsal circadian neurons to an LNd, regulates the evening phase in Drosophila.
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Affiliation(s)
- Madelen M Díaz
- Howard Hughes Medical Institute and National Center for Behavioral Genomics, Brandeis University, Waltham, MA 02454, USA
| | - Matthias Schlichting
- Howard Hughes Medical Institute and National Center for Behavioral Genomics, Brandeis University, Waltham, MA 02454, USA
| | - Katharine C Abruzzi
- Howard Hughes Medical Institute and National Center for Behavioral Genomics, Brandeis University, Waltham, MA 02454, USA
| | - Xi Long
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA 20147, USA
| | - Michael Rosbash
- Howard Hughes Medical Institute and National Center for Behavioral Genomics, Brandeis University, Waltham, MA 02454, USA.
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32
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Beauchamp M, Bertolini E, Deppisch P, Steubing J, Menegazzi P, Helfrich-Förster C. Closely Related Fruit Fly Species Living at Different Latitudes Diverge in Their Circadian Clock Anatomy and Rhythmic Behavior. J Biol Rhythms 2018; 33:602-613. [PMID: 30203704 DOI: 10.1177/0748730418798096] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Recently, we reported differences in the expression pattern of the blue light-sensitive flavoprotein cryptochrome (CRY) and the neuropeptide pigment-dispersing factor (PDF) in the neuronal clock network of high-latitude Drosophila species, belonging to the Drosophila subgenus ( virilis-repleta radiation), compared with cosmopolitan D. melanogaster flies, belonging to the Sophophora subgenus. Alterations in rhythmic patterns of activity due to these differences might have adaptive significance for colonizing high-latitude habitats and, hence, adjusting to long photoperiods. Here, we show that these differing CRY/PDF expression patterns are only present in those species of the virilis-repleta radiation that colonized high latitudes. The cosmopolitan species D. mercatorum and D. hydei have a D. melanogaster-like clock network and behavior despite belonging to the virilis-repleta radiation. Similarly, 2 species of the holotropical Zaprionus genus, more closely related to the Drosophila subgenus than to the Sophophora subgenus, retain a D. melanogaster-like clock network and rhythmic behavior. We therefore suggest that the D. melanogaster-like clock network is the "ancestral fly clock phenotype" and that alterations in the CRY/PDF clock neurochemistry have allowed some species of the virilis-repleta radiation to colonize high-latitude environments.
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Affiliation(s)
- Marta Beauchamp
- Neurobiology and Genetics, Biocenter, University of Würzburg, Würzburg, Germany
| | - Enrico Bertolini
- Neurobiology and Genetics, Biocenter, University of Würzburg, Würzburg, Germany
| | - Peter Deppisch
- Neurobiology and Genetics, Biocenter, University of Würzburg, Würzburg, Germany
| | - Jonathan Steubing
- Neurobiology and Genetics, Biocenter, University of Würzburg, Würzburg, Germany
| | - Pamela Menegazzi
- Neurobiology and Genetics, Biocenter, University of Würzburg, Würzburg, Germany
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33
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NonA and CPX Link the Circadian Clockwork to Locomotor Activity in Drosophila. Neuron 2018; 99:768-780.e3. [PMID: 30057203 DOI: 10.1016/j.neuron.2018.07.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 04/27/2018] [Accepted: 07/01/2018] [Indexed: 11/20/2022]
Abstract
Drosophila NonA and its mammalian ortholog NONO are members of the Drosophila behavior and human splicing (DBHS) family. NONO also has a strong circadian connection: it associates with the circadian repressor protein PERIOD (PER) and contributes to circadian timekeeping. Here, we investigate NonA, which is required for proper levels of evening locomotor activity as well as a normal free-running period in Drosophila. NonA is associated with the positive transcription factor CLOCK/CYCLE (CLK/CYC), interacts directly with complexin (cpx) pre-mRNA, and upregulates gene expression, including the gene cpx. Downregulation of cpx expression in circadian neurons phenocopies NonA downregulation, whereas cpx overexpression rescues the nonA RNAi phenotypes, indicating that cpx is an important NonA target gene. As the cpx protein contributes to proper neurotransmitter and neuropeptide release in response to calcium, these results and others indicate that this control is important for the normal circadian regulation of locomotor activity.
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34
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Neural Network Interactions Modulate CRY-Dependent Photoresponses in Drosophila. J Neurosci 2018; 38:6161-6171. [PMID: 29875268 DOI: 10.1523/jneurosci.2259-17.2018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 04/17/2018] [Accepted: 05/02/2018] [Indexed: 12/21/2022] Open
Abstract
Light is one of the chief environmental cues that reset circadian clocks. In Drosophila, CRYPTOCHROME (CRY) mediates acute photic resetting of circadian clocks by promoting the degradation of TIMELESS in a cell-autonomous manner. Thus, even circadian oscillators in peripheral organs can independently perceive light in Drosophila However, there is substantial evidence for nonautonomous mechanisms of circadian photoreception in the brain. We have previously shown that the morning (M) and evening (E) oscillators are critical light-sensing neurons that cooperate to shift the phase of circadian behavior in response to light input. We show here that light can efficiently phase delay or phase advance circadian locomotor behavior in male Drosophila even when either the M- or the E-oscillators are ablated, suggesting that behavioral phase shifts and their directionality are largely a consequence of the cell-autonomous nature of CRY-dependent photoreception. Our observation that the phase response curves of brain and peripheral oscillators are remarkably similar further supports this idea. Nevertheless, the neural network modulates circadian photoresponses. We show that the M-oscillator neurotransmitter pigment dispersing factor plays a critical role in the coordination between M- and E-oscillators after light exposure, and we uncover a potential role for a subset of dorsal neurons in the control of phase advances. Thus, neural modulation of autonomous light detection might play an important role in the plasticity of circadian behavior.SIGNIFICANCE STATEMENT Input pathways provide circadian rhythms with the flexibility needed to harmonize their phase with environmental cycles. Light is the chief environmental cue that synchronizes circadian clocks. In Drosophila, the photoreceptor CRYPTOCHROME resets circadian clocks cell-autonomously. However, recent studies indicate that, in the brain, interactions between clock neurons are critical to reset circadian locomotor behavior. We present evidence supporting the idea that the ability of flies to advance or delay their rhythmic behavior in response to light input essentially results from cell-autonomous photoreception. However, because of their networked organization, we find that circadian neurons have to cooperate to reset the phase of circadian behavior in response to photic cues. Our work thus helps to reconcile cell-autonomous and non-cell-autonomous models of circadian entrainment.
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35
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Schubert FK, Hagedorn N, Yoshii T, Helfrich-Förster C, Rieger D. Neuroanatomical details of the lateral neurons of Drosophila melanogaster support their functional role in the circadian system. J Comp Neurol 2018; 526:1209-1231. [PMID: 29424420 PMCID: PMC5873451 DOI: 10.1002/cne.24406] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 01/30/2018] [Accepted: 01/30/2018] [Indexed: 12/29/2022]
Abstract
Drosophila melanogaster is a long‐standing model organism in the circadian clock research. A major advantage is the relative small number of about 150 neurons, which built the circadian clock in Drosophila. In our recent work, we focused on the neuroanatomical properties of the lateral neurons of the clock network. By applying the multicolor‐labeling technique Flybow we were able to identify the anatomical similarity of the previously described E2 subunit of the evening oscillator of the clock, which is built by the 5th small ventrolateral neuron (5th s‐LNv) and one ITP positive dorsolateral neuron (LNd). These two clock neurons share the same spatial and functional properties. We found both neurons innervating the same brain areas with similar pre‐ and postsynaptic sites in the brain. Here the anatomical findings support their shared function as a main evening oscillator in the clock network like also found in previous studies. A second quite surprising finding addresses the large lateral ventral PDF‐neurons (l‐LNvs). We could show that the four hardly distinguishable l‐LNvs consist of two subgroups with different innervation patterns. While three of the neurons reflect the well‐known branching pattern reproduced by PDF immunohistochemistry, one neuron per brain hemisphere has a distinguished innervation profile and is restricted only to the proximal part of the medulla‐surface. We named this neuron “extra” l‐LNv (l‐LNvx). We suggest the anatomical findings reflect different functional properties of the two l‐LNv subgroups.
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Affiliation(s)
- Frank K Schubert
- Neurobiology and Genetics, Theodor-Boveri Institute, Biocenter, University of Würzburg, Würzburg, 97074, Germany
| | - Nicolas Hagedorn
- Neurobiology and Genetics, Theodor-Boveri Institute, Biocenter, University of Würzburg, Würzburg, 97074, Germany
| | - Taishi Yoshii
- Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Charlotte Helfrich-Förster
- Neurobiology and Genetics, Theodor-Boveri Institute, Biocenter, University of Würzburg, Würzburg, 97074, Germany
| | - Dirk Rieger
- Neurobiology and Genetics, Theodor-Boveri Institute, Biocenter, University of Würzburg, Würzburg, 97074, Germany
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36
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Bertolini E, Kistenpfennig C, Menegazzi P, Keller A, Koukidou M, Helfrich-Förster C. The characterization of the circadian clock in the olive fly Bactrocera oleae (Diptera: Tephritidae) reveals a Drosophila-like organization. Sci Rep 2018; 8:816. [PMID: 29339768 PMCID: PMC5770390 DOI: 10.1038/s41598-018-19255-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 12/20/2017] [Indexed: 12/20/2022] Open
Abstract
The olive fruit fly, Bactrocera oleae, is the single most important pest for the majority of olive plantations. Oxitec's self-limiting olive fly technology (OX3097D-Bol) offers an alternative management approach to this insect pest. Because of previously reported asynchrony in the mating time of wild and laboratory strains, we have characterized the olive fly circadian clock applying molecular, evolutionary, anatomical and behavioural approaches. Here we demonstrate that the olive fly clock relies on a Drosophila melanogaster-like organization and that OX3097D-Bol carries a functional clock similar to wild-type strains, confirming its suitability for operational use.
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Affiliation(s)
- Enrico Bertolini
- Neurobiology and Genetics, Theodor Boveri Institute, Biocentre, University of Würzburg, 97074, Würzburg, Germany
| | | | - Pamela Menegazzi
- Neurobiology and Genetics, Theodor Boveri Institute, Biocentre, University of Würzburg, 97074, Würzburg, Germany
| | - Alexander Keller
- Center for Computation and Theoretical Biology and Department of Bioinformatics, Biocentre, University of Würzburg, 97074, Würzburg, Germany
| | | | - Charlotte Helfrich-Förster
- Neurobiology and Genetics, Theodor Boveri Institute, Biocentre, University of Würzburg, 97074, Würzburg, Germany.
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37
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Menegazzi P, Dalla Benetta E, Beauchamp M, Schlichting M, Steffan-Dewenter I, Helfrich-Förster C. Adaptation of Circadian Neuronal Network to Photoperiod in High-Latitude European Drosophilids. Curr Biol 2017; 27:833-839. [PMID: 28262491 DOI: 10.1016/j.cub.2017.01.036] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 12/14/2016] [Accepted: 01/19/2017] [Indexed: 10/20/2022]
Abstract
The genus Drosophila contains over 2,000 species that, stemming from a common ancestor in the Old World Tropics, populate today very different environments [1, 2] (reviewed in [3]). We found significant differences in the activity pattern of Drosophila species belonging to the holarctic virilis group, i.e., D. ezoana and D. littoralis, collected in Northern Europe, compared to that of the cosmopolitan D. melanogaster, collected close to the equator. These behavioral differences might have been of adaptive significance for colonizing high-latitude habitats and hence adjust to long photoperiods. Most interestingly, the flies' locomotor activity correlates with the neurochemistry of their circadian clock network, which differs between low and high latitude for the expression pattern of the blue light photopigment cryptochrome (CRY) and the neuropeptide Pigment-dispersing factor (PDF) [4-6]. In D. melanogaster, CRY and PDF are known to modulate the timing of activity and to maintain robust rhythmicity under constant conditions [7-11]. We could partly simulate the rhythmic behavior of the high-latitude virilis group species by mimicking their CRY/PDF expression patterns in a laboratory strain of D. melanogaster. We therefore suggest that these alterations in the CRY/PDF clock neurochemistry might have allowed the virilis group species to colonize high-latitude environments.
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Affiliation(s)
- Pamela Menegazzi
- Neurobiology and Genetics, Theodor Boveri Institute, Biocentre, University of Würzburg, 97074 Würzburg, Germany
| | - Elena Dalla Benetta
- Neurobiology and Genetics, Theodor Boveri Institute, Biocentre, University of Würzburg, 97074 Würzburg, Germany
| | - Marta Beauchamp
- Neurobiology and Genetics, Theodor Boveri Institute, Biocentre, University of Würzburg, 97074 Würzburg, Germany
| | - Matthias Schlichting
- Neurobiology and Genetics, Theodor Boveri Institute, Biocentre, University of Würzburg, 97074 Würzburg, Germany
| | - Ingolf Steffan-Dewenter
- Department of Animal Ecology and Tropical Biology, Biocentre, University of Würzburg, 97074 Würzburg, Germany
| | - Charlotte Helfrich-Förster
- Neurobiology and Genetics, Theodor Boveri Institute, Biocentre, University of Würzburg, 97074 Würzburg, Germany.
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38
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Yao Z, Bennett AJ, Clem JL, Shafer OT. The Drosophila Clock Neuron Network Features Diverse Coupling Modes and Requires Network-wide Coherence for Robust Circadian Rhythms. Cell Rep 2016; 17:2873-2881. [PMID: 27974202 PMCID: PMC5161247 DOI: 10.1016/j.celrep.2016.11.053] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 11/09/2016] [Accepted: 11/17/2016] [Indexed: 11/18/2022] Open
Abstract
In animals, networks of clock neurons containing molecular clocks orchestrate daily rhythms in physiology and behavior. However, how various types of clock neurons communicate and coordinate with one another to produce coherent circadian rhythms is not well understood. Here, we investigate clock neuron coupling in the brain of Drosophila and demonstrate that the fly's various groups of clock neurons display unique and complex coupling relationships to core pacemaker neurons. Furthermore, we find that coordinated free-running rhythms require molecular clock synchrony not only within the well-characterized lateral clock neuron classes but also between lateral clock neurons and dorsal clock neurons. These results uncover unexpected patterns of coupling in the clock neuron network and reveal that robust free-running behavioral rhythms require a coherence of molecular oscillations across most of the fly's clock neuron network.
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Affiliation(s)
- Zepeng Yao
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Amelia J Bennett
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jenna L Clem
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Orie T Shafer
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA.
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39
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Semmens DC, Mirabeau O, Moghul I, Pancholi MR, Wurm Y, Elphick MR. Transcriptomic identification of starfish neuropeptide precursors yields new insights into neuropeptide evolution. Open Biol 2016; 6:150224. [PMID: 26865025 PMCID: PMC4772807 DOI: 10.1098/rsob.150224] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Neuropeptides are evolutionarily ancient mediators of neuronal signalling in nervous systems. With recent advances in genomics/transcriptomics, an increasingly wide range of species has become accessible for molecular analysis. The deuterostomian invertebrates are of particular interest in this regard because they occupy an ‘intermediate' position in animal phylogeny, bridging the gap between the well-studied model protostomian invertebrates (e.g. Drosophila melanogaster, Caenorhabditis elegans) and the vertebrates. Here we have identified 40 neuropeptide precursors in the starfish Asterias rubens, a deuterostomian invertebrate from the phylum Echinodermata. Importantly, these include kisspeptin-type and melanin-concentrating hormone-type precursors, which are the first to be discovered in a non-chordate species. Starfish tachykinin-type, somatostatin-type, pigment-dispersing factor-type and corticotropin-releasing hormone-type precursors are the first to be discovered in the echinoderm/ambulacrarian clade of the animal kingdom. Other precursors identified include vasopressin/oxytocin-type, gonadotropin-releasing hormone-type, thyrotropin-releasing hormone-type, calcitonin-type, cholecystokinin/gastrin-type, orexin-type, luqin-type, pedal peptide/orcokinin-type, glycoprotein hormone-type, bursicon-type, relaxin-type and insulin-like growth factor-type precursors. This is the most comprehensive identification of neuropeptide precursor proteins in an echinoderm to date, yielding new insights into the evolution of neuropeptide signalling systems. Furthermore, these data provide a basis for experimental analysis of neuropeptide function in the unique context of the decentralized, pentaradial echinoderm bauplan.
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Affiliation(s)
- Dean C Semmens
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Olivier Mirabeau
- Institut Curie, Genetics and Biology of Cancers Unit, INSERM U830, PSL Research University, Paris 75005, France
| | - Ismail Moghul
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Mahesh R Pancholi
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Yannick Wurm
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Maurice R Elphick
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
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Kauranen H, Ala-Honkola O, Kankare M, Hoikkala A. Circadian clock of Drosophila montana is adapted to high variation in summer day lengths and temperatures prevailing at high latitudes. JOURNAL OF INSECT PHYSIOLOGY 2016; 89:9-18. [PMID: 26993661 DOI: 10.1016/j.jinsphys.2016.03.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 03/09/2016] [Accepted: 03/11/2016] [Indexed: 06/05/2023]
Abstract
Photoperiodic regulation of the circadian rhythms in insect locomotor activity has been studied in several species, but seasonal entrainment of these rhythms is still poorly understood. We have traced the entrainment of activity rhythm of northern Drosophila montana flies in a climate chamber mimicking the photoperiods and day and night temperatures that the flies encounter in northern Finland during the summer. The experiment was started by transferring freshly emerged females into the chamber in early and late summer conditions to obtain both non-diapausing and diapausing females for the studies. The locomotor activity of the females and daily changes in the expression levels of two core circadian clock genes, timeless and period, in their heads were measured at different times of summer. The study revealed several features in fly rhythmicity that are likely to help the flies to cope with high variation in the day length and temperature typical to northern summers. First, both the non-diapausing and the diapausing females showed evening activity, which decreased towards the short day length as observed in the autumn in nature. Second, timeless and period genes showed concordant daily oscillations and seasonal shifts in their expression level in both types of females. Contrary to Drosophila melanogaster, oscillation profiles of these genes were similar to each other in all conditions, including the extremely long days in early summer and the cool temperatures in late summer, and their peak expression levels were not locked to lights-off transition in any photoperiod. Third, the diapausing females were less active than the non-diapausing ones, in spite of their younger age. Overall, the study showed that D. montana clock functions well under long day conditions, and that both the photoperiod and the daily temperature cycles are important zeitgebers for seasonal changes in the circadian rhythm of this species.
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Affiliation(s)
- Hannele Kauranen
- University of Jyväskylä, Department of Biological and Environmental Science, P.O. Box 35, Jyväskylä, Finland.
| | - Outi Ala-Honkola
- University of Jyväskylä, Department of Biological and Environmental Science, P.O. Box 35, Jyväskylä, Finland
| | - Maaria Kankare
- University of Jyväskylä, Department of Biological and Environmental Science, P.O. Box 35, Jyväskylä, Finland
| | - Anneli Hoikkala
- University of Jyväskylä, Department of Biological and Environmental Science, P.O. Box 35, Jyväskylä, Finland
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Frolov RV. Current advances in invertebrate vision: insights from patch-clamp studies of photoreceptors in apposition eyes. J Neurophysiol 2016; 116:709-23. [PMID: 27250910 DOI: 10.1152/jn.00288.2016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 05/24/2016] [Indexed: 11/22/2022] Open
Abstract
Traditional electrophysiological research on invertebrate photoreceptors has been conducted in vivo, using intracellular recordings from intact compound eyes. The only exception used to be Drosophila melanogaster, which was exhaustively studied by both intracellular recording and patch-clamp methods. Recently, several patch-clamp studies have provided new information on the biophysical properties of photoreceptors of diverse insect species, having both apposition and neural superposition eyes, in the contexts of visual ecology, behavior, and ontogenesis. Here, I discuss these and other relevant results, emphasizing differences between fruit flies and other species, between photoreceptors of diurnal and nocturnal insects, properties of distinct functional types of photoreceptors, postembryonic developmental changes, and relationships between voltage-gated potassium channels and visual ecology.
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Affiliation(s)
- Roman V Frolov
- Department of Physics, Division of Biophysics, University of Oulu, Oulun Yliopisto, Finland
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Frolov R, Immonen EV, Weckström M. Visual ecology and potassium conductances of insect photoreceptors. J Neurophysiol 2016; 115:2147-57. [PMID: 26864762 DOI: 10.1152/jn.00795.2015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 02/06/2016] [Indexed: 01/22/2023] Open
Abstract
Voltage-activated potassium channels (Kv channels) in the microvillar photoreceptors of arthropods are responsible for repolarization and regulation of photoreceptor signaling bandwidth. On the basis of analyzing Kv channels in dipteran flies, it was suggested that diurnal, rapidly flying insects predominantly express sustained K(+) conductances, whereas crepuscular and nocturnally active animals exhibit strongly inactivating Kv conductances. The latter was suggested to function for minimizing cellular energy consumption. In this study we further explore the evolutionary adaptations of the photoreceptor channelome to visual ecology and behavior by comparing K(+) conductances in 15 phylogenetically diverse insects, using patch-clamp recordings from dissociated ommatidia. We show that rapid diurnal flyers such as the blowfly (Calliphora vicina) and the honeybee (Apis mellifera) express relatively large noninactivating Kv conductances, conforming to the earlier hypothesis in Diptera. Nocturnal and/or slow-moving species do not in general exhibit stronger Kv conductance inactivation in the physiological membrane voltage range, but the photoreceptors in species that are known to rely more on vision behaviorally had higher densities of sustained Kv conductances than photoreceptors of less visually guided species. No statistically significant trends related to visual performance could be identified for the rapidly inactivating Kv conductances. Counterintuitively, strong negative correlations were observed between photoreceptor capacitance and specific membrane conductance for both sustained and inactivating fractions of Kv conductance, suggesting insignificant evolutionary pressure to offset negative effects of high capacitance on membrane filtering with increased conductance.
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Affiliation(s)
- Roman Frolov
- Department of Physics, Division of Biophysics, University of Oulu, Oulun Yliopisto, Finland
| | - Esa-Ville Immonen
- Department of Physics, Division of Biophysics, University of Oulu, Oulun Yliopisto, Finland
| | - Matti Weckström
- Department of Physics, Division of Biophysics, University of Oulu, Oulun Yliopisto, Finland
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Prabhakaran PM, Sheeba V. Simulating natural light and temperature cycles in the laboratory reveals differential effects on activity/rest rhythm of four Drosophilids. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2014; 200:849-62. [PMID: 25048564 DOI: 10.1007/s00359-014-0927-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 05/21/2014] [Accepted: 07/03/2014] [Indexed: 11/28/2022]
Abstract
Recent studies under semi-natural conditions have revealed various unique features of activity/rest rhythms in Drosophilids that differ from those under standard laboratory conditions. An additional afternoon peak (A-peak) has been reported for Drosophila melanogaster and another species D. malerkotliana while D. ananassae exhibited mostly unimodal diurnal activity. To tease apart the role of light and temperature in mediating these species-specific behaviours of four Drosophilid species D. melanogaster, D. malerkotliana, D. ananassae, and Zaprionus indianus we simulated gradual natural light and/or temperature cycles conditions in laboratory. The pattern observed under semi-natural conditions could be reproduced in the laboratory for all the species under a variety of simulated conditions. D. melanogaster and D. malerkotliana showed similar patterns where as D. ananassae consistently exhibited predominant morning activity under almost all regimes. Z. indianus showed clearly rhythmic activity mostly when temperature cycles were provided. We find that gradually changing light intensities reaching a sufficiently high peak value can elicit A-peak in D. melanogaster, D. malerkotliana, and D. ananassae even at mild ambient temperature. Furthermore, we show that high mid-day temperature could induce A-peak in all species even under constant light conditions suggesting that this A-peak is likely to be a stress response.
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Affiliation(s)
- Priya M Prabhakaran
- Behavioural Neurogenetics Laboratory, Evolutionary and Organismal Biology Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, PB # 6436, Jakkur Post, Bangalore, 560064, India
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Guo F, Cerullo I, Chen X, Rosbash M. PDF neuron firing phase-shifts key circadian activity neurons in Drosophila. eLife 2014; 3. [PMID: 24939987 PMCID: PMC4092873 DOI: 10.7554/elife.02780] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 06/16/2014] [Indexed: 01/06/2023] Open
Abstract
Our experiments address two long-standing models for the function of the Drosophila brain circadian network: a dual oscillator model, which emphasizes the primacy of PDF-containing neurons, and a cell-autonomous model for circadian phase adjustment. We identify five different circadian (E) neurons that are a major source of rhythmicity and locomotor activity. Brief firing of PDF cells at different times of day generates a phase response curve (PRC), which mimics a light-mediated PRC and requires PDF receptor expression in the five E neurons. Firing also resembles light by causing TIM degradation in downstream neurons. Unlike light however, firing-mediated phase-shifting is CRY-independent and exploits the E3 ligase component CUL-3 in the early night to degrade TIM. Our results suggest that PDF neurons integrate light information and then modulate the phase of E cell oscillations and behavioral rhythms. The results also explain how fly brain rhythms persist in constant darkness and without CRY. DOI:http://dx.doi.org/10.7554/eLife.02780.001 Most animals have daily rhythms of activity: some are awake during the day and asleep at night, whilst others are more active at night, or during the twilight hours around dawn and dusk. These cycles of activity are driven by an internal body clock, which is reset in response to external cues, like light and temperature, and which keeps the animal in sync with the day–night cycle. The fruit fly Drosophila has daily—or circadian—rhythms of behavior, which are controlled by a network of genes that are switched ‘on’ or ‘off’ at different times in every 24-hr period. These circadian genes encode various proteins, including PERIOD and TIMELESS. The levels of these two proteins increase during the day and into the night, until they reach a point at which they cause their own genes to be switched off. PERIOD and TIMELESS are then destroyed each morning, and the cycle begins anew. Most of these same proteins perform similar functions in mammals. In the fly brain, two groups of neurons express these key proteins and control the timings of activity or movement. One group, called M cells, regulates activity in the morning and also produces a small molecule called PDF. Another group, called E cells, controls evening activity, but is less well-defined. Since M cells can maintain circadian rhythms even in total darkness, these cells were also considered key ‘pacemaker neurons’. However, Guo et al. now challenge this view by identifying five E cells that are the major source of circadian activity. Blocking the release of signaling molecules from these neurons severely disrupted movement in both the morning and the evening. The E cells are also critical for timekeeping under a normal day–night cycle. Guo et al. found that the rhythm of the E cells is reset when the M cell neurons fire, which causes a release of PDF molecules. Further, PDF molecules reset the E cells by causing the degradation of the TIMELESS protein—which is similar to the effect of light, although light cause TIMELESS to be degraded via a different biochemical pathway. Guo et al. suggest that under normal light–dark conditions the E cells are important for driving the flies' activity as well as for overall timekeeping. The M cells, instead, appear to function primarily to integrate information about light and reset the E cell clock. Challenges moving forward will include understanding other ways in which the firing of neurons can affect timekeeping, as well as looking if there any differences between the five E cells. DOI:http://dx.doi.org/10.7554/eLife.02780.002
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Affiliation(s)
- Fang Guo
- Department of Biology, Brandeis University, Waltham, United States
| | - Isadora Cerullo
- Howard Hughes Medical Institute, Brandeis University, Waltham, United States
| | - Xiao Chen
- Department of Biology, Brandeis University, Waltham, United States
| | - Michael Rosbash
- Department of Biology, Brandeis University, Waltham, United States
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Morning and evening oscillators cooperate to reset circadian behavior in response to light input. Cell Rep 2014; 7:601-8. [PMID: 24746814 DOI: 10.1016/j.celrep.2014.03.044] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 02/12/2014] [Accepted: 03/17/2014] [Indexed: 12/11/2022] Open
Abstract
Light is a crucial input for circadian clocks. In Drosophila, short light exposure can robustly shift the phase of circadian behavior. The model for this resetting posits that circadian photoreception is cell autonomous: CRYPTOCHROME senses light, binds to TIMELESS (TIM), and promotes its degradation, which is mediated by JETLAG (JET). However, it was recently proposed that interactions between circadian neurons are also required for phase resetting. We identify two groups of neurons critical for circadian photoreception: the morning (M) and the evening (E) oscillators. These neurons work synergistically to reset rhythmic behavior. JET promotes acute TIM degradation cell autonomously in M and E oscillators but also nonautonomously in E oscillators when expressed in M oscillators. Thus, upon light exposure, the M oscillators communicate with the E oscillators. Because the M oscillators drive circadian behavior, they must also receive inputs from the E oscillators. Hence, although photic TIM degradation is largely cell autonomous, neural cooperation between M and E oscillators is critical for circadian behavioral photoresponses.
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Prabhakaran PM, De J, Sheeba V. Natural conditions override differences in emergence rhythm among closely related drosophilids. PLoS One 2013; 8:e83048. [PMID: 24349430 PMCID: PMC3859640 DOI: 10.1371/journal.pone.0083048] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2013] [Accepted: 11/07/2013] [Indexed: 11/19/2022] Open
Abstract
Previous studies on adult emergence rhythm of Drosophila melanogaster (DM) done under semi-natural conditions have shown that emergence is correlated to daily changes in temperature, humidity and light at dawn. Recently we showed that under laboratory conditions D. ananassae (DA), a closely related species of DM exhibits patterns in its activity/rest rhythm distinct from the latter. Here, we report the results of a study aimed at examining whether this difference in activity/rest rhythm among species extends to other circadian behaviours such as the adult emergence rhythm under a more natural environment with multiple cyclic time cues. We monitored the adult emergence rhythm of recently wild-caught DM and DA populations in parallel with those of a related species D. malerkotliana (DK), both in the laboratory and under semi-natural conditions. We find that although DM, DK and DA showed marked difference from one another under laboratory conditions, such differences were not detectable in the emergence behaviour of these three species under semi-natural conditions, and that they respond very similarly to seasonal changes in the environment. The results suggest that seasonal changes in temperature and humidity contribute largely to the variation in adult emergence waveform in terms of gate width, phase and amplitude of the peak and day-to-day variance in the timing of the emergence peak. In all three species, seasons with cooler and wetter conditions make the rhythm less tightly gated, with low amplitude peak and high day-to-day variation in timing of the peak of emergence. We show that in nature the emergence rhythm of DM, DK and DA is strongly influenced by environmental factors such that in a given season all of them exhibit similar time course and waveform and that with the changing season, they all modify their emergence patterns in a similar manner.
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Affiliation(s)
- Priya M. Prabhakaran
- Behavioural Neurogenetics Laboratory, Evolutionary and Organismal Biology Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, Karnataka, India
| | - Joydeep De
- Behavioural Neurogenetics Laboratory, Evolutionary and Organismal Biology Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, Karnataka, India
| | - Vasu Sheeba
- Behavioural Neurogenetics Laboratory, Evolutionary and Organismal Biology Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, Karnataka, India
- * E-mail:
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47
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Prabhakaran PM, Sheeba V. Insights into differential activity patterns of drosophilids under semi-natural conditions. ACTA ACUST UNITED AC 2013; 216:4691-702. [PMID: 24143027 DOI: 10.1242/jeb.092270] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
We showed recently that Drosophila ananassae, a closely related and sympatric species of the commonly studied fruitfly D. melanogaster, shows distinctly deviant patterns in circadian activity/rest rhythm from the latter under a variety of laboratory conditions. To examine whether such differences extend to more natural conditions where a variety of time cues and similar environmental pressures might force different species to adopt similar temporal patterns, we examined these two species under semi-natural conditions over a span of 1.5 years. Furthermore, we asked to what extent features of activity/rest rhythm of flies are conserved across species under changing environmental conditions encountered across seasons, and to do so, we studied two more drosophilid species. We found that while each species exhibits seasonality in activity patterns, this seasonality is marked by interesting inter-specific differences. Similar to laboratory studies, D. ananassae showed activity mostly during the day, while D. melanogaster and D. malerkotliana exhibited almost similar activity patterns across seasons, with predominantly two peaks of activity, one in the morning and another in the evening. Throughout the year, Zaprionus indianus displayed very low levels of activity compared with D. melanogaster, yet, compared with those seen in standard laboratory assays, this species exhibited more robust rhythms under semi-natural conditions. We hypothesise that different ecological factors may have influenced these species to adopt different temporal niches.
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Affiliation(s)
- Priya M Prabhakaran
- Behavioural Neurogenetics Laboratory, Evolutionary and Organismal Biology Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore-560064, India
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Hermann C, Saccon R, Senthilan PR, Domnik L, Dircksen H, Yoshii T, Helfrich-Förster C. The circadian clock network in the brain of different Drosophila species. J Comp Neurol 2013; 521:367-88. [PMID: 22736465 DOI: 10.1002/cne.23178] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Revised: 05/22/2012] [Accepted: 06/21/2012] [Indexed: 12/16/2022]
Abstract
Comparative studies on cellular and molecular clock mechanisms have revealed striking similarities in the organization of the clocks among different animal groups. To gain evolutionary insight into the properties of the clock network within the Drosophila genus, we analyzed sequence identities and similarities of clock protein homologues and immunostained brains of 10 different Drosophila species using antibodies against vrille (VRI), PAR-protein domain1 (PDP1), and cryptochrome (CRY). We found that the clock network of both subgenera Sophophora and Drosophila consists of all lateral and dorsal clock neuron clusters that were previously described in Drosophila melanogaster. Immunostaining against CRY and the neuropeptide pigment-dispersing factor (PDF), however, revealed species-specific differences. All species of the Drosophila subgenus and D. pseudoobscura of the Sophophora subgenus completely lacked CRY in the large ventrolateral clock neurons (lLN(v) s) and showed reduced PDF immunostaining in the small ventrolateral clock neurons (sLN(v) s). In contrast, we found the expression of the ion transport peptide (ITP) to be consistent within the fifth sLN(v) and one dorsolateral clock neuron (LN(d) ) in all investigated species, suggesting a conserved putative function of this neuropeptide in the clock. We conclude that the general anatomy of the clock network is highly conserved throughout the Drosophila genus, although there is variation in PDF and CRY expression. Our comparative study is a first step toward understanding the organization of the circadian clock in Drosophila species adapted to different habitats.
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Affiliation(s)
- Christiane Hermann
- Neurobiology and Genetics, Theodor-Boveri Institute, Biocenter, University of Würzburg, Würzburg, Germany
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Kauranen H, Menegazzi P, Costa R, Helfrich-Förster C, Kankainen A, Hoikkala A. Flies in the north: locomotor behavior and clock neuron organization of Drosophila montana. J Biol Rhythms 2013; 27:377-87. [PMID: 23010660 DOI: 10.1177/0748730412455916] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The circadian clock plays an important role in adaptation in time and space by synchronizing changes in physiological, developmental, and behavioral traits of organisms with daily and seasonal changes in their environment. We have studied some features of the circadian activity and clock organization in a northern Drosophila species, Drosophila montana, at both the phenotypic and the neuronal levels. In the first part of the study, we monitored the entrained and free-running locomotor activity rhythms of females in different light-dark and temperature regimes. These studies showed that D. montana flies completely lack the morning activity component typical to more southern Drosophila species in an entrained environment and that they are able to maintain their free-running locomotor activity rhythm better in constant light than in constant darkness. In the second part of the study, we traced the expression of the PDF neuropeptide and the CRY protein in the neurons of the brain in D. montana adults and found differences in the number and location of PDF- and CRY-expressing neurons compared with those described in Drosophila melanogaster. These differences could account, at least in part, for the lack of morning activity and the reduced circadian rhythmicity of D. montana flies in constant darkness, both of which are likely to be adaptive features during the long and dark winters occurring in nature.
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Affiliation(s)
- Hannele Kauranen
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland.
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Luo W, Li Y, Tang CHA, Abruzzi KC, Rodriguez J, Pescatore S, Rosbash M. CLOCK deubiquitylation by USP8 inhibits CLK/CYC transcription in Drosophila. Genes Dev 2013; 26:2536-49. [PMID: 23154984 DOI: 10.1101/gad.200584.112] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
A conserved transcriptional feedback loop underlies animal circadian rhythms. In Drosophila, the transcription factors CLOCK (CLK) and CYCLE (CYC) activate the transcription of direct target genes like period (per) and timeless (tim). They encode the proteins PER and TIM, respectively, which repress CLK/CYC activity. Previous work indicates that repression is due to a direct PER-CLK/CYC interaction as well as CLK/CYC phosphorylation. We describe here the role of ubiquitin-specific protease 8 (USP8) in circadian transcriptional repression as well as the importance of CLK ubiquitylation in CLK/CYC transcription activity. usp8 loss of function (RNAi) or expression of a dominant-negative form of the protein (USP8-DN) enhances CLK/CYC transcriptional activity and alters fly locomotor activity rhythms. Clock protein and mRNA molecular oscillations are virtually absent within circadian neurons of USP8-DN flies. Furthermore, CLK ubiquitylation cycles robustly in wild-type flies and peaks coincident with maximal CLK/CYC transcription. As USP8 interacts with CLK and expression of USP8-DN increases CLK ubiquitylation, the data indicate that USP8 deubiquitylates CLK, which down-regulates CLK/CYC transcriptional activity. Taken together with the facts that usp8 mRNA cycles and that its transcription is activated directly by CLK/CYC, USP8, like PER and TIM, contributes to the transcriptional feedback loop cycle that underlies circadian rhythms.
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