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Villegas G, Pereira MT, Love CR, Edery I. DAYWAKE implicates novel roles for circulating lipid-binding proteins as extracerebral regulators of daytime wake-sleep behavior. FEBS Lett 2024; 598:321-330. [PMID: 38112219 PMCID: PMC10922413 DOI: 10.1002/1873-3468.14789] [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: 11/07/2023] [Revised: 11/28/2023] [Accepted: 11/29/2023] [Indexed: 12/21/2023]
Abstract
Sleep during the midday, commonly referred to as siesta, is a common trait of animals that mainly sleep during the night. Work using Drosophila led to the identification of the daywake (dyw) gene, found to have anti-siesta activity. Herein, we show that the DYW protein undergoes signal peptide-dependent secretion, is present in the circulatory system, and accumulates in multiple organs, but, surprisingly, it is not detected in the brain where wake-sleep centers are located. The abundance of DYW in adult flies is regulated by age, sex, temperature, and the splicing efficiency of a nearby thermosensitive intron. We suggest that DYW regulates daytime wake-sleep balance in an indirect, extracerebral manner, via a multi-organ network that interfaces with the circulatory system.
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Affiliation(s)
- Gabriel Villegas
- Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, NJ, USA
- Department of Molecular Biology and Biochemistry, Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, NJ, USA
| | - Mathew T Pereira
- Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, NJ, USA
| | - Cameron R Love
- Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, NJ, USA
| | - Isaac Edery
- Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, NJ, USA
- Department of Molecular Biology and Biochemistry, Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, NJ, USA
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Mariano V, Kanellopoulos AK, Aiello G, Lo AC, Legius E, Achsel T, Bagni C. SREBP modulates the NADP +/NADPH cycle to control night sleep in Drosophila. Nat Commun 2023; 14:763. [PMID: 36808152 PMCID: PMC9941135 DOI: 10.1038/s41467-022-35577-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Accepted: 12/12/2022] [Indexed: 02/22/2023] Open
Abstract
Sleep behavior is conserved throughout evolution, and sleep disturbances are a frequent comorbidity of neuropsychiatric disorders. However, the molecular basis underlying sleep dysfunctions in neurological diseases remains elusive. Using a model for neurodevelopmental disorders (NDDs), the Drosophila Cytoplasmic FMR1 interacting protein haploinsufficiency (Cyfip85.1/+), we identify a mechanism modulating sleep homeostasis. We show that increased activity of the sterol regulatory element-binding protein (SREBP) in Cyfip85.1/+ flies induces an increase in the transcription of wakefulness-associated genes, such as the malic enzyme (Men), causing a disturbance in the daily NADP+/NADPH ratio oscillations and reducing sleep pressure at the night-time onset. Reduction in SREBP or Men activity in Cyfip85.1/+ flies enhances the NADP+/NADPH ratio and rescues the sleep deficits, indicating that SREBP and Men are causative for the sleep deficits in Cyfip heterozygous flies. This work suggests modulation of the SREBP metabolic axis as a new avenue worth exploring for its therapeutic potential in sleep disorders.
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Affiliation(s)
- Vittoria Mariano
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, 1005, Switzerland.,Department of Human Genetics, KU Leuven, Leuven, 3000, Belgium
| | | | - Giuseppe Aiello
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, 1005, Switzerland
| | - Adrian C Lo
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, 1005, Switzerland
| | - Eric Legius
- Department of Human Genetics, KU Leuven, Leuven, 3000, Belgium
| | - Tilmann Achsel
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, 1005, Switzerland
| | - Claudia Bagni
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, 1005, Switzerland. .,Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, 00133, Italy.
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Lee SH, Kim EY. Short-term maintenance on a high-sucrose diet alleviates aging-induced sleep fragmentation in drosophila. Anim Cells Syst (Seoul) 2021; 25:377-386. [PMID: 35059137 PMCID: PMC8765278 DOI: 10.1080/19768354.2021.1997801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Sleep is a fundamental behavior in an animal’s life influenced by many internal and external factors, such as aging and diet. Critically, poor sleep quality places people at risk of serious medical conditions. Because aging impairs quality of sleep, measures to improve sleep quality for elderly people are needed. Given that diet can influence many aspects of sleep, we investigated whether a high-sucrose diet (HSD) affected aging-induced sleep fragmentation using the fruit fly, Drosophila melanogaster. Drosophila is a valuable model for studying sleep due to its genetic tractability and many similarities with mammalian sleep. Total sleep duration, sleep bout numbers (SBN), and average sleep bout length (ABL) were compared between young and old flies on a normal sucrose diet (NSD) or HSD. On the NSD, old flies slept slightly more and showed increased SBN and reduced ABL, indicating increased sleep fragmentation. Short-term maintenance of flies in HSD (up to 8 days), but not long-term maintenance (up to 35 days), suppressed aging-induced sleep fragmentation. Our study provides meaningful strategies for preventing the deterioration of sleep quality in the elderly.
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Affiliation(s)
- Sang Hyuk Lee
- Department of Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon, Republic of Korea
- Department of Brain Science, Ajou University Medical Center, Suwon, Republic of Korea
| | - Eun Young Kim
- Department of Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon, Republic of Korea
- Department of Brain Science, Ajou University Medical Center, Suwon, Republic of Korea
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De Nobrega AK, Lyons LC. Aging and the clock: Perspective from flies to humans. Eur J Neurosci 2020; 51:454-481. [PMID: 30269400 PMCID: PMC6441388 DOI: 10.1111/ejn.14176] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Revised: 09/10/2018] [Accepted: 09/17/2018] [Indexed: 12/15/2022]
Abstract
Endogenous circadian oscillators regulate molecular, cellular and physiological rhythms, synchronizing tissues and organ function to coordinate activity and metabolism with environmental cycles. The technological nature of modern society with round-the-clock work schedules and heavy reliance on personal electronics has precipitated a striking increase in the incidence of circadian and sleep disorders. Circadian dysfunction contributes to an increased risk for many diseases and appears to have adverse effects on aging and longevity in animal models. From invertebrate organisms to humans, the function and synchronization of the circadian system weakens with age aggravating the age-related disorders and pathologies. In this review, we highlight the impacts of circadian dysfunction on aging and longevity and the reciprocal effects of aging on circadian function with examples from Drosophila to humans underscoring the highly conserved nature of these interactions. Additionally, we review the potential for using reinforcement of the circadian system to promote healthy aging and mitigate age-related pathologies. Advancements in medicine and public health have significantly increased human life span in the past century. With the demographics of countries worldwide shifting to an older population, there is a critical need to understand the factors that shape healthy aging. Drosophila melanogaster, as a model for aging and circadian interactions, has the capacity to facilitate the rapid advancement of research in this area and provide mechanistic insights for targeted investigations in mammals.
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Affiliation(s)
- Aliza K De Nobrega
- Program in Neuroscience, Department of Biological Science, Florida State University, Tallahassee, Florida
| | - Lisa C Lyons
- Program in Neuroscience, Department of Biological Science, Florida State University, Tallahassee, Florida
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Daywake, an Anti-siesta Gene Linked to a Splicing-Based Thermostat from an Adjoining Clock Gene. Curr Biol 2019; 29:1728-1734.e4. [PMID: 31080079 DOI: 10.1016/j.cub.2019.04.039] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 02/26/2019] [Accepted: 04/12/2019] [Indexed: 01/25/2023]
Abstract
Sleep is fundamental to animal survival but is a vulnerable state that also limits how much time can be devoted to critical wake-dependent activities [1]. Although many animals are day-active and sleep at night, they exhibit a midday nap, or "siesta," that can vary in intensity and is usually more prominent on warm days. In humans, the balance between maintaining the wake state or sleeping during the day has important health implications [2], but the mechanisms underlying this dynamic regulation are poorly understood. Using the well-established Drosophila melanogaster animal model to study sleep [3], we identify a new wake-sleep regulator that we term daywake (dyw). dyw encodes a juvenile hormone-binding protein [4] that functions in neurons as a day-specific anti-siesta gene, with little effect on sleep levels during the nighttime or in the absence of light. Remarkably, dyw expression is stimulated in trans via cold-enhanced splicing of the dmpi8 intron [5] from the reverse-oriented but slightly overlapping period (per) clock gene [6]. The functionally integrated dmpi8-dyw genetic unit operates as a "behavioral temperate acclimator" by increasingly counterbalancing siesta-promoting pathways as daily temperatures become cooler and carry reduced risks from daytime heat exposure. While daily patterns of when animals are awake and when they sleep are largely scheduled by the circadian timing system, dyw implicates a less recognized class of modulatory wake-sleep regulators that primarily function to enhance flexibility in wake-sleep preference, a behavioral plasticity that is commonly observed in animals during the midday, raising the possibility of shared mechanisms.
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6
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Yang Y, Edery I. Parallel clinal variation in the mid-day siesta of Drosophila melanogaster implicates continent-specific targets of natural selection. PLoS Genet 2018; 14:e1007612. [PMID: 30180162 PMCID: PMC6138418 DOI: 10.1371/journal.pgen.1007612] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 09/14/2018] [Accepted: 08/06/2018] [Indexed: 11/18/2022] Open
Abstract
Similar to many diurnal animals, Drosophila melanogaster exhibits a mid-day siesta that is more robust as ambient temperature rises, an adaptive response aimed at minimizing exposure to heat. Mid-day siesta levels are partly regulated by the thermosensitive splicing of a small intron (termed dmpi8) found in the 3’ untranslated region (UTR) of the circadian clock gene period (per). Using the well-studied D. melanogaster latitudinal cline along the eastern coast of Australia, we show that flies from temperate populations sleep less during the day compared to those from tropical regions. We identified combinations of four single nucleotide polymorphisms (SNPs) in the 3’ UTR of per that yield several different haplotypes. The two most abundant of these haplotypes exhibit a reciprocal tropical-temperate distribution in relative frequency. Intriguingly, transgenic flies with the major tropical isoform manifest increased daytime sleep and reduced dmpi8 splicing compared to those carrying the temperate variant. Our results strongly suggest that for a major portion of D. melanogaster in Australia, thermal adaptation of daily sleep behavior included spatially varying selection on ancestrally derived polymorphisms in the per 3’ UTR that differentially control dmpi8 splicing efficiency. Prior work showed that African flies from high altitudes manifest reduced mid-day siesta levels, indicative of parallel latitudinal and altitudinal adaptation across continents. However, geographical variation in per 3’ UTR haplotypes was not observed for African flies, providing a compelling case for inter-continental variation in factors targeted by natural selection in attaining a parallel adaptation. We propose that the ability to calibrate mid-day siesta levels to better match local temperature ranges is a key adaptation contributing to the successful colonization of D. melanogaster beyond its ancestral range in the lowlands of Sub-Saharan Africa. In warm climates many animals, including humans, exhibit a mid-day siesta, almost certainly a behavior meant to minimize the harm from prolonged exposure to the hot mid-day sun. But what about animals that adapted to cooler more temperate climates, might they have a less pronounced siesta? Indeed, we show that in the common fruit fly, Drosophila melanogaster, those from temperate regions in Australia exhibit less mid-day siesta compared to their tropical counterparts. Prior work showed that mid-day sleep levels are partially regulated by a ‘clock’ gene called period (per), which controls the timing of wake-sleep cycles in addition to other daily rhythms. We identified several DNA differences in the per gene that show geographical variation and contribute to the daytime sleep differences in flies from tropical and temperate regions via a mechanism that involves how well a temperature-sensitive intron in per is removed. A similar reduction in mid-day sleep was previously observed in African flies that adapted to the cooler temperatures found at high altitudes. Together, our findings provide a rare example where latitude and altitude lead to a similar behavioral adaptation to temperature. Moreover, the results suggest inter-continental differences in the evolutionary solutions used to attain the same thermal adaptation to cooler climates.
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Affiliation(s)
- Yong Yang
- Rutgers University, Center for Advanced Biotechnology and Medicine, New Jersey, United States of America
| | - Isaac Edery
- Rutgers University, Center for Advanced Biotechnology and Medicine, New Jersey, United States of America
- Department of Molecular Biology and Biochemistry, Rutgers University, Center for Advanced Biotechnology and Medicine, New Jersey, United States of America
- * E-mail:
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Zhang Z, Cao W, Edery I. The SR protein B52/SRp55 regulates splicing of the period thermosensitive intron and mid-day siesta in Drosophila. Sci Rep 2018; 8:1872. [PMID: 29382842 PMCID: PMC5789894 DOI: 10.1038/s41598-017-18167-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 12/06/2017] [Indexed: 11/24/2022] Open
Abstract
Similar to many diurnal animals, Drosophila melanogaster exhibits a mid-day siesta that is more robust as temperature increases, an adaptive response that aims to minimize the deleterious effects from exposure to heat. This temperature-dependent plasticity in mid-day sleep levels is partly based on the thermal sensitive splicing of an intron in the 3' untranslated region (UTR) of the circadian clock gene termed period (per). In this study, we evaluated a possible role for the serine/arginine-rich (SR) splicing factors in the regulation of dmpi8 splicing efficiency and mid-day siesta. Using a Drosophila cell culture assay we show that B52/SRp55 increases dmpi8 splicing efficiency, whereas other SR proteins have little to no effect. The magnitude of the stimulatory effect of B52 on dmpi8 splicing efficiency is modulated by natural variation in single nucleotide polymorphisms (SNPs) in the per 3' UTR that correlate with B52 binding levels. Down-regulating B52 expression in clock neurons increases mid-day siesta and reduces dmpi8 splicing efficiency. Our results establish a novel role for SR proteins in sleep and suggest that polymorphisms in the per 3' UTR contribute to natural variation in sleep behavior by modulating the binding efficiencies of SR proteins.
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Affiliation(s)
- Zhichao Zhang
- Rutgers University, Center for Advanced Biotechnology and Medicine, Piscataway, NJ, 08854, USA
- Institute of Animal Genetics and Breeding, Sichuan Agriculture University, Huimin Road 211#, Chengdu, Sichuan Province, 611130, P. R. China
| | - Weihuan Cao
- Rutgers University, Center for Advanced Biotechnology and Medicine, Piscataway, NJ, 08854, USA
- Human Genetics Institute of New Jersey, Nelson Biology Laboratories, 604 Allison Road, Piscataway, NJ, 08854, USA
| | - Isaac Edery
- Department of Molecular Biology and Biochemistry, Rutgers University, Center for Advanced Biotechnology and Medicine, Piscataway, NJ, 08854, USA.
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Selection for long and short sleep duration in Drosophila melanogaster reveals the complex genetic network underlying natural variation in sleep. PLoS Genet 2017; 13:e1007098. [PMID: 29240764 PMCID: PMC5730107 DOI: 10.1371/journal.pgen.1007098] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 11/01/2017] [Indexed: 12/16/2022] Open
Abstract
Why do some individuals need more sleep than others? Forward mutagenesis screens in flies using engineered mutations have established a clear genetic component to sleep duration, revealing mutants that convey very long or short sleep. Whether such extreme long or short sleep could exist in natural populations was unknown. We applied artificial selection for high and low night sleep duration to an outbred population of Drosophila melanogaster for 13 generations. At the end of the selection procedure, night sleep duration diverged by 9.97 hours in the long and short sleeper populations, and 24-hour sleep was reduced to 3.3 hours in the short sleepers. Neither long nor short sleeper lifespan differed appreciably from controls, suggesting little physiological consequences to being an extreme long or short sleeper. Whole genome sequence data from seven generations of selection revealed several hundred thousand changes in allele frequencies at polymorphic loci across the genome. Combining the data from long and short sleeper populations across generations in a logistic regression implicated 126 polymorphisms in 80 candidate genes, and we confirmed three of these genes and a larger genomic region with mutant and chromosomal deficiency tests, respectively. Many of these genes could be connected in a single network based on previously known physical and genetic interactions. Candidate genes have known roles in several classic, highly conserved developmental and signaling pathways—EGFR, Wnt, Hippo, and MAPK. The involvement of highly pleiotropic pathway genes suggests that sleep duration in natural populations can be influenced by a wide variety of biological processes, which may be why the purpose of sleep has been so elusive. One of the biggest mysteries in biology is the need to sleep. Sleep duration has an underlying genetic basis, suggesting that very long and short sleep times could be bred for experimentally. How far can sleep duration be driven up or down? Here we achieved extremely long and short night sleep duration by subjecting a wild-derived population of Drosophila melanogaster to an experimental breeding program. At the end of the breeding program, long sleepers averaged 9.97 hours more nightly sleep than short sleepers. We analyzed whole-genome sequences from seven generations of the experimental breeding to identify allele frequencies that diverged between long and short sleepers, and verified genes and genomic regions with mutation and deficiency testing. These alleles map to classic developmental and signaling pathways, implicating many diverse processes that potentially affect sleep duration.
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Pharmacodynamic study on insomnia-curing effects of Shuangxia Decoction in Drosophila melanogaster. Chin J Nat Med 2017; 14:653-660. [PMID: 27667510 DOI: 10.1016/s1875-5364(16)30077-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Indexed: 12/25/2022]
Abstract
The present study aimed to establish a pharmacodynamic method using the pySolo software to explore the influence of freeze-dried powders of Shuangxia Decoction (SXD) on the sleep of normal Drosophila melanogaster and the Drosophila melanogaster whose sleep was divested by light. The dose-effect and the time-effect relationships of SXD on sleep were examined. The effect-onset concentration of SXD was 0.25%, the plateau appeared at the concentration of 2.5% and the total sleep time showed a downtrend when the concentration was greater than 2.5%. The sleep time was the longest on the fourth day after SXD was given. The fruit fly sleep deprivation model was repeated by light stimulation at night. The middle dosage group (2.5%) had the best insomnia-curing effect. In conclusion, using the pySolo software, an approach for the pharmacodynamics study was established with Drosophila melanogaster as a model organism to determine the insomnia-curing effects of the traditional Chinese medicine (TCM). Our results demonstrated the reliability of this method. The freeze-dried powders of SXD could effectively improve the sleep quality of Drosophila melanogaster.
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Mid-day siesta in natural populations of D. melanogaster from Africa exhibits an altitudinal cline and is regulated by splicing of a thermosensitive intron in the period clock gene. BMC Evol Biol 2017; 17:32. [PMID: 28114910 PMCID: PMC5259850 DOI: 10.1186/s12862-017-0880-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 01/11/2017] [Indexed: 01/18/2023] Open
Abstract
Background Many diurnal animals exhibit a mid-day ‘siesta’, generally thought to be an adaptive response aimed at minimizing exposure to heat on warm days, suggesting that in regions with cooler climates mid-day siestas might be a less prominent feature of animal behavior. Drosophila melanogaster exhibits thermal plasticity in its mid-day siesta that is partly governed by the thermosensitive splicing of the 3’-terminal intron (termed dmpi8) from the key circadian clock gene period (per). For example, decreases in temperature lead to progressively more efficient splicing, which increasingly favors activity over sleep during the mid-day. In this study we sought to determine if the adaptation of D. melanogaster from its ancestral range in the lowlands of tropical Africa to the cooler temperatures found at high altitudes involved changes in mid-day sleep behavior and/or dmpi8 splicing efficiency. Results Using natural populations of Drosophila melanogaster from different altitudes in tropical Africa we show that flies from high elevations have a reduced mid-day siesta and less consolidated sleep. We identified a single nucleotide polymorphism (SNP) in the per 3’ untranslated region that has strong effects on dmpi8 splicing and mid-day sleep levels in both low and high altitude flies. Intriguingly, high altitude flies with a particular variant of this SNP exhibit increased dmpi8 splicing efficiency compared to their low altitude counterparts, consistent with reduced mid-day siesta. Thus, a boost in dmpi8 splicing efficiency appears to have played a prominent but not universal role in how African flies adapted to the cooler temperatures at high altitude. Conclusions Our findings point towards mid-day sleep behavior as a key evolutionary target in the thermal adaptation of animals, and provide a genetic framework for investigating daytime sleep in diurnal animals which appears to be driven by mechanisms distinct from those underlying nighttime sleep. Electronic supplementary material The online version of this article (doi:10.1186/s12862-017-0880-8) contains supplementary material, which is available to authorized users.
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Nystrand M, Cassidy EJ, Dowling DK. Transgenerational plasticity following a dual pathogen and stress challenge in fruit flies. BMC Evol Biol 2016; 16:171. [PMID: 27567640 PMCID: PMC5002108 DOI: 10.1186/s12862-016-0737-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 08/08/2016] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Phenotypic plasticity operates across generations, when the parental environment affects phenotypic expression in the offspring. Recent studies in invertebrates have reported transgenerational plasticity in phenotypic responses of offspring when the mothers had been previously exposed to either live or heat-killed pathogens. Understanding whether this plasticity is adaptive requires a factorial design in which both mothers and their offspring are subjected to either the pathogen challenge or a control, in experimentally matched and mismatched combinations. Most prior studies exploring the capacity for pathogen-mediated transgenerational plasticity have, however, failed to adopt such a design. Furthermore, it is currently poorly understood whether the magnitude or direction of pathogen-mediated transgenerational responses will be sensitive to environmental heterogeneity. Here, we explored the transgenerational consequences of a dual pathogen and stress challenge administered in the maternal generation in the fruit fly, Drosophila melanogaster. Prospective mothers were assigned to a non-infectious pathogen treatment consisting of an injection with heat-killed bacteria or a procedural control, and a stress treatment consisting of sleep deprivation or control. Their daughters and sons were similarly assigned to the same pathogen treatment, prior to measurement of their reproductive success. RESULTS We observed transgenerational interactions involving pathogen treatments of mothers and their offspring, on the reproductive success of daughters but not sons. These interactions were unaffected by sleep deprivation. CONCLUSIONS The direction of the transgenerational effects was not consistent with that predicted under a scenario of adaptive transgenerational plasticity. Instead, they were indicative of expectations based on terminal investment.
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Affiliation(s)
- M. Nystrand
- School of Biological Sciences, Monash University, Clayton, VIC 3800 Australia
| | - E. J. Cassidy
- School of Biological Sciences, Monash University, Clayton, VIC 3800 Australia
| | - D. K. Dowling
- School of Biological Sciences, Monash University, Clayton, VIC 3800 Australia
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12
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Sleep- and wake-dependent changes in neuronal activity and reactivity demonstrated in fly neurons using in vivo calcium imaging. Proc Natl Acad Sci U S A 2015; 112:4785-90. [PMID: 25825756 DOI: 10.1073/pnas.1419603112] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Sleep in Drosophila shares many features with mammalian sleep, but it remains unknown whether spontaneous and evoked activity of individual neurons change with the sleep/wake cycle in flies as they do in mammals. Here we used calcium imaging to assess how the Kenyon cells in the fly mushroom bodies change their activity and reactivity to stimuli during sleep, wake, and after short or long sleep deprivation. As before, sleep was defined as a period of immobility of >5 min associated with a reduced behavioral response to a stimulus. We found that calcium levels in Kenyon cells decline when flies fall asleep and increase when they wake up. Moreover, calcium transients in response to two different stimuli are larger in awake flies than in sleeping flies. The activity of Kenyon cells is also affected by sleep/wake history: in awake flies, more cells are spontaneously active and responding to stimuli if the last several hours (5-8 h) before imaging were spent awake rather than asleep. By contrast, long wake (≥29 h) reduces both baseline and evoked neural activity and decreases the ability of neurons to respond consistently to the same repeated stimulus. The latter finding may underlie some of the negative effects of sleep deprivation on cognitive performance and is consistent with the occurrence of local sleep during wake as described in behaving rats. Thus, calcium imaging uncovers new similarities between fly and mammalian sleep: fly neurons are more active and reactive in wake than in sleep, and their activity tracks sleep/wake history.
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13
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Cao W, Edery I. A novel pathway for sensory-mediated arousal involves splicing of an intron in the period clock gene. Sleep 2015; 38:41-51. [PMID: 25325457 DOI: 10.5665/sleep.4322] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 05/17/2014] [Indexed: 01/07/2023] Open
Abstract
STUDY OBJECTIVES D. melanogaster is an excellent animal model to study how the circadian (≅24-h) timing system and sleep regulate daily wake-sleep cycles. Splicing of a temperature-sensitive 3'-terminal intron (termed dmpi8) from the circadian clock gene period (per) regulates the distribution of daily activity in Drosophila. The role of dmpi8 splicing on daily behavior was further evaluated by analyzing sleep. DESIGN Transgenic flies of the same genetic background but expressing either a wild-type recombinant per gene or one where the efficiency of dmpi8 splicing was increased were exposed to different temperatures in daily light-dark cycles and sleep parameters measured. In addition, transgenic flies were briefly exposed to a variety of sensory-mediated stimuli to measure arousal responses. RESULTS Surprisingly, we show that the effect of dmpi8 splicing on daytime activity levels does not involve a circadian role for per but is linked to adjustments in sensory-dependent arousal and sleep behavior. Genetically altered flies with high dmpi8 splicing efficiency remain aroused longer following short treatments with light and non-photic cues such as mechanical stimulation. CONCLUSIONS We propose that the thermal regulation of dmpi8 splicing acts as a temperature-calibrated rheostat in a novel arousal mechanism, so that on warm days the inefficient splicing of the dmpi8 intron triggers an increase in quiescence by decreasing sensory-mediated arousal, thus ensuring flies minimize being active during the hot midday sun despite the presence of light in the environment, which is usually a strong arousal cue for diurnal animals.
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Affiliation(s)
- Weihuan Cao
- Rutgers University, Center for Advanced Biotechnology and Medicine, Piscataway, NJ
| | - Isaac Edery
- Department of Molecular Biology and Biochemistry, Rutgers University, Center for Advanced Biotechnology and Medicine, Piscataway, NJ
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14
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Abstract
Sleep is a complex behavior both in its manifestation and regulation, that is common to almost all animal species studied thus far. Sleep is not a unitary behavior and has many different aspects, each of which is tightly regulated and influenced by both genetic and environmental factors. Despite its essential role for performance, health, and well-being, genetic mechanisms underlying this complex behavior remain poorly understood. One important aspect of sleep concerns its homeostatic regulation, which ensures that levels of sleep need are kept within a range still allowing optimal functioning during wakefulness. Uncovering the genetic pathways underlying the homeostatic aspect of sleep is of particular importance because it could lead to insights concerning sleep's still elusive function and is therefore a main focus of current sleep research. In this chapter, we first give a definition of sleep homeostasis and describe the molecular genetics techniques that are used to examine it. We then provide a conceptual discussion on the problem of assessing a sleep homeostatic phenotype in various animal models. We finally highlight some of the studies with a focus on clock genes and adenosine signaling molecules.
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Affiliation(s)
- Géraldine M Mang
- Center for Integrative Genomics, University of Lausanne, Genopode Building, 1015, Lausanne-Dorigny, Switzerland,
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Chiu JC, Kaub K, Zou S, Liedo P, Altamirano-Robles L, Ingram D, Carey JR. Deleterious effect of suboptimal diet on rest-activity cycle in Anastrepha ludens manifests itself with age. Sci Rep 2014; 3:1773. [PMID: 23639915 PMCID: PMC3642661 DOI: 10.1038/srep01773] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2012] [Accepted: 04/15/2013] [Indexed: 12/26/2022] Open
Abstract
Activity patterns and sleep-wake cycles are among the physiological processes that change most prominently as animals age, and are often good indicators of healthspan. In this study, we used the video-based high-resolution Behavioral Monitoring System (BMS) to monitor the daily activity cycle of tephritid fruit flies Anastrepha ludens over their lifetime. Surprisingly, there was no dramatic change in activity profile with respect to age if flies were consistently fed with a nutritionally balanced diet. However, if flies were fed with sugar-only diet, their activity profile decreased in amplitude at old age, suggesting that suboptimal diet affected activity patterns, and its detrimental effect may not manifest itself until the animal ages. Moreover, by simulating different modes of behavior monitoring with a range of resolution and comparing the resulting conclusions, we confirmed the superior performance of video-based monitoring using high-resolution BMS in accurately representing activity patterns in an insect model.
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Affiliation(s)
- Joanna C Chiu
- Department of Entomology, College of Agricultural and Environmental Sciences, University of California, Davis, CA 95616, USA
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16
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Oh Y, Jang D, Sonn JY, Choe J. Histamine-HisCl1 receptor axis regulates wake-promoting signals in Drosophila melanogaster. PLoS One 2013; 8:e68269. [PMID: 23844178 PMCID: PMC3700972 DOI: 10.1371/journal.pone.0068269] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Accepted: 05/29/2013] [Indexed: 12/21/2022] Open
Abstract
Histamine and its two receptors, histamine-gated chloride channel subunit 1 (HisCl1) and ora transientless (Ort), are known to control photoreception and temperature sensing in Drosophila. However, histamine signaling in the context of neural circuitry for sleep-wake behaviors has not yet been examined in detail. Here, we obtained mutant flies with compromised or enhanced histamine signaling and tested their baseline sleep. Hypomorphic mutations in histidine decarboxylase (HDC), an enzyme catalyzing the conversion from histidine to histamine, caused an increase in sleep duration. Interestingly, hisCl1 mutants but not ort mutants showed long-sleep phenotypes similar to those in hdc mutants. Increased sleep duration in hisCl1 mutants was rescued by overexpressing hisCl1 in circadian pacemaker neurons expressing a neuropeptide pigment dispersing factor (PDF). Consistently, RNA interference (RNAi)-mediated depletion of hisCl1 in PDF neurons was sufficient to mimic hisCl1 mutant phenotypes, suggesting that PDF neurons are crucial for sleep regulation by the histamine-HisCl1 signaling. Finally, either hisCl1 mutation or genetic ablation of PDF neurons dampened wake-promoting effects of elevated histamine signaling via direct histamine administration. Taken together, these data clearly demonstrate that the histamine-HisCl1 receptor axis can activate and maintain the wake state in Drosophila and that wake-activating signals may travel via the PDF neurons.
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Affiliation(s)
- Yangkyun Oh
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Donghoon Jang
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Jun Young Sonn
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Joonho Choe
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
- * E-mail:
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17
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van Alphen B, van Swinderen B. Drosophila strategies to study psychiatric disorders. Brain Res Bull 2013; 92:1-11. [DOI: 10.1016/j.brainresbull.2011.09.007] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 09/08/2011] [Accepted: 09/09/2011] [Indexed: 01/03/2023]
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18
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Okray Z, Hassan BA. Genetic approaches in Drosophila for the study neurodevelopmental disorders. Neuropharmacology 2012; 68:150-6. [PMID: 23067575 DOI: 10.1016/j.neuropharm.2012.09.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Revised: 08/31/2012] [Accepted: 09/07/2012] [Indexed: 12/16/2022]
Abstract
The fruit fly Drosophila melanogaster is one of the premier genetic model organisms used in biomedical research today owing to the extraordinary power of its genetic tool-kit. Made famous by numerous seminal discoveries of basic developmental mechanisms and behavioral genetics, the power of fruit fly genetics is becoming increasingly applied to questions directly relevant to human health. In this review we discuss how Drosophila research is applied to address major questions in neurodevelopmental disorders. This article is part of the Special Issue entitled 'Neurodevelopmental Disorders'.
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Affiliation(s)
- Zeynep Okray
- Laboratory of Neurogenetics, VIB Center for the Biology of Disease, VIB, Herestraat 49, Leuven, Belgium
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19
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Venken KJ, Simpson JH, Bellen HJ. Genetic manipulation of genes and cells in the nervous system of the fruit fly. Neuron 2011; 72:202-30. [PMID: 22017985 PMCID: PMC3232021 DOI: 10.1016/j.neuron.2011.09.021] [Citation(s) in RCA: 301] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/26/2011] [Indexed: 12/26/2022]
Abstract
Research in the fruit fly Drosophila melanogaster has led to insights in neural development, axon guidance, ion channel function, synaptic transmission, learning and memory, diurnal rhythmicity, and neural disease that have had broad implications for neuroscience. Drosophila is currently the eukaryotic model organism that permits the most sophisticated in vivo manipulations to address the function of neurons and neuronally expressed genes. Here, we summarize many of the techniques that help assess the role of specific neurons by labeling, removing, or altering their activity. We also survey genetic manipulations to identify and characterize neural genes by mutation, overexpression, and protein labeling. Here, we attempt to acquaint the reader with available options and contexts to apply these methods.
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Affiliation(s)
- Koen J.T. Venken
- Department of Molecular and Human Genetics, Neurological Research Institute, Baylor College of Medicine, Houston, Texas, 77030
| | - Julie H. Simpson
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia, 20147
| | - Hugo J. Bellen
- Department of Molecular and Human Genetics, Neurological Research Institute, Baylor College of Medicine, Houston, Texas, 77030
- Program in Developmental Biology, Department of Neuroscience, Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas, 77030
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21
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Bushey D, Cirelli C. From genetics to structure to function: exploring sleep in Drosophila. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2011; 99:213-44. [PMID: 21906542 DOI: 10.1016/b978-0-12-387003-2.00009-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Sleep consists of quiescent periods with reduced responsiveness to external stimuli. Despite being maladaptive in that when asleep, animals are less able to respond to dangerous stimuli; sleep behavior is conserved in all animal species studied to date. Thus, sleep must be performing at least one fundamental, conserved function that is necessary, and/or whose benefits outweigh its maladaptive consequences. Currently, there is no consensus on what that function might be. Over the last 10 years, multiple groups have started to characterize the molecular mechanisms and brain structures necessary for normal sleep in Drosophila melanogaster. These researchers are exploiting genetic tools developed in Drosophila over the past century to identify and manipulate gene expression. Forward genetic screens can identify molecular components in complex biological systems and once identified, these genes can be manipulated within specific brain areas to determine which neuronal groups are important to initiate and maintain sleep. Screening for mutations and brain regions necessary for normal sleep has revealed that several genes that affect sleep are involved in synaptic plasticity and have preferential expression in the mushroom bodies (MBs). Moreover, altering MB neuronal activity alters sleep. Previous genetic screens found that the same genes enriched in MB are necessary for learning and memory. Increasing evidence in mammals, including humans, points to a beneficial role for sleep in synaptic plasticity, learning and memory. Thus, results from both flies and mammals suggest a strong link between sleep need and wake plasticity.
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Affiliation(s)
- Daniel Bushey
- Department of Psychiatry, University of Wisconsin, 6001 Research Park Blvd.Madison, WI 53719, USA
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22
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Affiliation(s)
- Chiara Cirelli
- Department of Psychiatry, University of Wisconsin, Madison, WI 53719, USA.
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23
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Abstract
Normal aging can be defined as the natural physiological changes that occur in an organism over time in the absence of any disease. Among the many age-related changes that can be observed are those that result in the progressive decline of a variety of behavioral responses, including locomotor activity and cognitive function. During the past decade, model organisms, such as the fruit fly Drosophila melanogaster, have been used extensively to study aging. These simpler model systems have been particularly useful for genetic studies of aging because of their small genome size, short generation time, and mean life span compared to either mice or humans. Drosophila also exhibits complex behaviors, many of which undergo age-related decline. Here, we describe the age-related changes in behavior that have been observed in Drosophila and discuss how these are affected in long- and short-lived strains of flies.
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Affiliation(s)
- Konstantin G Iliadi
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
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Bushey D, Hughes KA, Tononi G, Cirelli C. Sleep, aging, and lifespan in Drosophila. BMC Neurosci 2010; 11:56. [PMID: 20429945 PMCID: PMC2871268 DOI: 10.1186/1471-2202-11-56] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2009] [Accepted: 04/29/2010] [Indexed: 11/30/2022] Open
Abstract
Background Epidemiological studies in humans suggest that a decrease in daily sleep duration is associated with reduced lifespan, but this issue remains controversial. Other studies in humans also show that both sleep quantity and sleep quality decrease with age. Drosophila melanogaster is a useful model to study aging and sleep, and inheriting mutations affecting the potassium current Shaker results in flies that sleep less and have a shorter lifespan. However, whether the link between short sleep and reduced longevity exists also in wild-type flies is unknown. Similarly, it is unknown whether such a link depends on sleep amount per se, rather than on other factors such as waking activity. Also, sleep quality has been shown to decrease in old flies, but it remains unclear whether aging-related sleep fragmentation is a generalized phenomenon. Results We compared 3 short sleeping mutant lines (Hk1, HkY and Hk2) carrying a mutation in Hyperkinetic, which codes for the beta subunit of the Shaker channel, to wild-type siblings throughout their entire lifespan (all flies kept at 20°C). Hk1 and HkY mutants were short sleeping relative to wild-type controls from day 3 after eclosure, and Hk2 flies became short sleepers about two weeks later. All 3 Hk mutant lines had reduced lifespan relative to wild-type flies. Total sleep time showed a trend to increase in all lines with age, but the effect was most pronounced in Hk1 and HkY flies. In both mutant and wild-type lines sleep quality did not decay with age, but the strong preference for sleep at night declined starting in "middle age". Using Cox regression analysis we found that in Hk1 and HkY mutants and their control lines there was a negative relationship between total sleep amount during the first 2 and 4 weeks of age and hazard (individual risk of death), while no association was found in Hk2 flies and their wild-type controls. Hk1 and HkY mutants and their control lines also showed an association between total daily wake activity over the first 2 and 4 weeks of age and hazard. However, when both sleep duration and wake activity were used in the same regression, the effects of activity were much reduced, while most of the sleep effects remained significant. Finally, Hk1 flies and wild-type siblings were also tested at 25°C, and results were similar to those at 20°C. Namely, Hk1 mutants were short sleeping, hyperactive, and short lived relative to controls, and sleep quality in both groups did not decrease with age. Conclusions Different Hk mutations affect the sleep phenotype, and do so in an age-dependent manner. In 4 of the 6 lines tested sleep associates significantly with lifespan variation even after any effect of activity is removed, but activity does not associate significantly with lifespan after the effects of sleep are removed. Thus, in addition to environmental factors and genetic background, sleep may also affect longevity. Sleep quality does not necessarily decay as flies age, suggesting that aging-related sleep fragmentation may also depend on many factors, including genetic background and rearing conditions.
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Affiliation(s)
- Daniel Bushey
- Dept of Psychiatry, University of Wisconsin/Madison, Madison, Wisconsin 53719, USA
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25
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Ho KS, Sehgal A. Drosophila melanogaster: an insect model for fundamental studies of sleep. Methods Enzymol 2008; 393:772-93. [PMID: 15817324 DOI: 10.1016/s0076-6879(05)93041-3] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
In 2000, Drosophila melanogaster joined the ranks of vertebrates and invertebrates with a defined behavioral sleep state. The characterization of this sleep state revealed striking similarities to sleep in humans: sleep in flies has both circadian and homeostatic components, it is influenced by sex and age, and it is affected by pharmacological agents such as caffeine and antihistamines. As in mammals, arousal thresholds in flies increase with sleep deprivation. Furthermore, changes in brain electrical activity accompany the change from wake to sleep states. Not only do flies and vertebrates share these behavioral and physiological traits of sleep, but they are likely to share at least some genetic mechanisms underlying the regulation of sleep as well. This article reviews the methods currently used to identify and characterize the Drosophila sleep state. As these methods become more refined and our understanding of Drosophila sleep more detailed, the powerful techniques afforded by this organism are likely to unveil deep insights into the function(s) and regulatory mechanisms of sleep.
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Affiliation(s)
- Karen S Ho
- Department of Neuroscience, Howard Hughes Medical Institute, University of Pennsylvania Medical School, Philadelphia, Pennsylvania 19104, USA
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26
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Abstract
No current hypothesis can explain why animals need to sleep. Yet, sleep is universal, tightly regulated, and cannot be deprived without deleterious consequences. This suggests that searching for a core function of sleep, particularly at the cellular level, is still a worthwhile exercise.
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Affiliation(s)
- Chiara Cirelli
- Department of Psychiatry, University of Wisconsin, Madison, Wisconsin, United States of America.
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27
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Wu MN, Koh K, Yue Z, Joiner WJ, Sehgal A. A genetic screen for sleep and circadian mutants reveals mechanisms underlying regulation of sleep in Drosophila. Sleep 2008; 31:465-72. [PMID: 18457233 DOI: 10.1093/sleep/31.4.465] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
STUDY OBJECTIVES In order to characterize the genetic mechanisms underlying sleep, we have carried out a large-scale screen in Drosophila to identify short-sleeping mutants. The objectives of this study were as follows: (1) characterize the phenotypes of the shortest-sleeping mutants; (2) examine whether changes in arousal threshold or sleep homeostasis underlie short-sleeping phenotypes; (3) clone a gene affected in one of the shortest sleepers; and (4) investigate whether circadian mutants can be identified using light:dark (L:D) locomotor data obtained for studying sleep behavior. DESIGN Locomotor activity was measured using the Drosophila Activity Monitoring System in a 12:12 L:D cycle. SETTING Drosophila research laboratory. PARTICIPANTS Adult flies from the 2nd chromosome Zuker collection, which contain mutations in most of the nonessential genes on the Drosophila 2nd chromosome. MEASUREMENTS AND RESULTS Our analysis of sleep characteristics suggests that daily activity (but not waking activity) correlates with daily sleep time and that defects in sleep maintenance are more common than defects in sleep initiation. Our shortest sleepers have intact or increased sleep rebound following sleep deprivation but show reduced thresholds for arousal. Molecular analysis of one of the short-sleeping lines indicates that it is a novel allele of a dopamine transporter (DAT). Finally, we describe a novel approach for identifying circadian mutants using L:D data. CONCLUSIONS Our data suggest that most short-sleeping mutant phenotypes in Drosophila are characterized by an inability to stay asleep, most likely because of a reduced arousal threshold.
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Affiliation(s)
- Mark N Wu
- Division of Sleep Medicine, Department of Neurology, University of Pennsylvania, Philadelphia, PA 19104, USA
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28
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Abstract
Sleep is present and tightly regulated in every vertebrate species in which it has been carefully investigated, but what sleep is for remains a mystery. Sleep is also present in invertebrates, and an extensive analysis in Drosophila melanogaster has shown that sleep in fruit flies shows most of the fundamental features that characterize sleep in mammals. In Drosophila, sleep consists of sustained periods of quiescence associated with an increased arousal threshold. Fly sleep is modulated by several of the same stimulants and hypnotics that affect mammalian sleep. Moreover, like in mammals, fly sleep shows remarkable interindividual variability. The expression of several genes involved in energy metabolism, synaptic plasticity, and the response to cellular stress varies in Drosophila between sleep and wakefulness, and the same occurs in rodents. Brain activity also changes in flies as a function of behavioral state. Furthermore, Drosophila sleep is tightly regulated in a circadian and homeostatic manner, and the homeostatic regulation is largely independent of the circadian regulation. After sleep deprivation, recovery sleep in flies is longer in duration and more consolidated, indicated by an increase in arousal threshold and fewer brief awakenings. Finally, sleep deprivation in flies impairs vigilance and performance. Because of the extensive similarities between flies and mammals, Drosophila is now being used as a promising model system for the genetic dissection of sleep. Over the last few years, mutagenesis screens have isolated several short sleeping mutants, a demonstration that single genes can have a powerful effect on a complex trait like sleep.
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Affiliation(s)
- Chaira Cirelli
- Department of Psychiatry, University of Wisconsin/Madison, 6001 Research Park Blvd., Madison, WI 53719, USA.
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29
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Abstract
Understanding the genetic and environmental factors affecting human complex genetic traits and diseases is a major challenge because of many interacting genes with individually small effects, whose expression is sensitive to the environment. Dissection of complex traits using the powerful genetic approaches available with Drosophila melanogaster has provided important lessons that should be considered when studying human complex traits. In Drosophila, large numbers of pleiotropic genes affect complex traits; quantitative trait locus alleles often have sex-, environment-, and genetic background-specific effects, and variants associated with different phenotypic are in noncoding as well as coding regions of candidate genes. Such insights, in conjunction with the strong evolutionary conservation of key genes and pathways between flies and humans, make Drosophila an excellent model system for elucidating the genetic mechanisms that affect clinically relevant human complex traits, such as alcohol dependence, sleep, and neurodegenerative diseases.
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Affiliation(s)
- Trudy F C Mackay
- Department of Genetics, North Carolina State University, Raleigh, North Carolina, 27695, USA.
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30
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Abstract
The genetic, molecular and anatomical dissection of the circadian clock in Drosophila and other higher organisms relies on the quantification of rhythmic phenotypes. Here, we introduce the methods currently in use in our laboratories for the analysis of fly locomotor activity rhythms. This phenotype provides a relatively simple, automated, efficient, reliable and robust output for the circadian clock. Thus it is not surprising that it is the preferred readout for measuring rhythmicity under a variety of conditions for most fly clock laboratories. The procedure requires at least 10 days of data collection and several days for analysis. In this protocol we advise on fly maintenance and on experimental design when studying the genetics of behavioral traits. We describe the setup for studying locomotor activity rhythms in the fruit fly and we introduce the statistical methods in use in our laboratories for the analysis of periodic data.
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Affiliation(s)
- Ezio Rosato
- Department of Genetics, University of Leicester, University Road, Leicester, LE1 7RH, UK
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31
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Pitman JL, McGill JJ, Keegan KP, Allada R. A dynamic role for the mushroom bodies in promoting sleep in Drosophila. Nature 2006; 441:753-6. [PMID: 16760979 DOI: 10.1038/nature04739] [Citation(s) in RCA: 243] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2006] [Accepted: 03/21/2006] [Indexed: 11/08/2022]
Abstract
The fruitfly, Drosophila melanogaster, exhibits many of the cardinal features of sleep, yet little is known about the neural circuits governing its sleep. Here we have performed a screen of GAL4 lines expressing a temperature-sensitive synaptic blocker shibire(ts1) (ref. 2) in a range of discrete neural circuits, and assayed the amount of sleep at different temperatures. We identified three short-sleep lines at the restrictive temperature with shared expression in the mushroom bodies, a neural locus central to learning and memory. Chemical ablation of the mushroom bodies also resulted in reduced sleep. These studies highlight a central role for the mushroom bodies in sleep regulation.
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Affiliation(s)
- Jena L Pitman
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Ilinois 60208, USA
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32
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Cirelli C, Bushey D, Hill S, Huber R, Kreber R, Ganetzky B, Tononi G. Reduced sleep in Drosophila Shaker mutants. Nature 2005; 434:1087-92. [PMID: 15858564 DOI: 10.1038/nature03486] [Citation(s) in RCA: 331] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2005] [Accepted: 02/23/2005] [Indexed: 11/08/2022]
Abstract
Most of us sleep 7-8 h per night, and if we are deprived of sleep our performance suffers greatly; however, a few do well with just 3-4 h of sleep-a trait that seems to run in families. Determining which genes underlie this phenotype could shed light on the mechanisms and functions of sleep. To do so, we performed mutagenesis in Drosophila melanogaster, because flies also sleep for many hours and, when sleep deprived, show sleep rebound and performance impairments. By screening 9,000 mutant lines, we found minisleep (mns), a line that sleeps for one-third of the wild-type amount. We show that mns flies perform normally in a number of tasks, have preserved sleep homeostasis, but are not impaired by sleep deprivation. We then show that mns flies carry a point mutation in a conserved domain of the Shaker gene. Moreover, after crossing out genetic modifiers accumulated over many generations, other Shaker alleles also become short sleepers and fail to complement the mns phenotype. Finally, we show that short-sleeping Shaker flies have a reduced lifespan. Shaker, which encodes a voltage-dependent potassium channel controlling membrane repolarization and transmitter release, may thus regulate sleep need or efficiency.
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Affiliation(s)
- Chiara Cirelli
- Department of Psychiatry, 6001 Research Park Blvd, University of Wisconsin Madison, Madison, Wisconsin 53719, USA
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33
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Abstract
A mechanistic study of consciousness need not be confined to human complexity. Other animals also display key behaviors and responses that have long been intimately tied to the measure of consciousness in humans. Among them are some very well-defined and measurable endpoints: selective attention, sleep and general anesthesia. That these three variables associated with changes in consciousness might exist even in a fruit-fly does not necessarily imply that a fly is "conscious", but it does suggest that some of the problems central to the field of consciousness studies could be investigated in a model organism such as Drosophila melanogaster. Demonstrating suppression of unattended stimuli, which is central to attention studies in humans, is now possible in Drosophila by measuring neural correlates of visual selection. By combining such studies with an eventual understanding of suppression in other arousal states in the fly, such as sleep and general anesthesia, we might be unraveling mechanisms relevant to consciousness as well.
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Affiliation(s)
- Bruno van Swinderen
- The Neurosciences Institute, 10640 John Jay Hopkins Dr, San Diego, CA 92121, USA.
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34
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Anholt RRH, Mackay TFC. Quantitative genetic analyses of complex behaviours in Drosophila. Nat Rev Genet 2004; 5:838-49. [PMID: 15520793 DOI: 10.1038/nrg1472] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Behaviours are exceptionally complex quantitative traits. Sensitivity to environmental variation and genetic background, the presence of sexual dimorphism, and the widespread functional pleiotropy that is inherent in behavioural phenotypes pose daunting challenges for unravelling their underlying genetics. Drosophila melanogaster provides an attractive system for elucidating the unifying principles of the genetic architectures that drive behaviours, as genetically identical individuals can be reared rapidly in controlled environments and extensive publicly accessible genetic resources are available. Recent advances in quantitative genetic and functional genomic approaches now enable the extensive characterization of complex genetic networks that mediate behaviours in this important model organism.
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Affiliation(s)
- Robert R H Anholt
- Department of Zoology, W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, North Carolina 27695-7617, USA.
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35
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Abstract
Behaviors are quantitative traits determined through actions of multiple genes and subject to genome-environment interactions. Early studies concentrated on analyzing the effects of single genes on behaviors, often generating views of simplified linear genetic pathways. The genome era has generated a profound paradigm shift enabling us to identify all the genes that contribute to expression of a behavioral phenotype, to investigate how they are organized as functional ensembles and to begin to identify polymorphisms that contribute to phenotypic variation and are targets for natural selection. Recent studies show that the genetic architecture of behavior is determined by dynamic and plastic modular networks of pleiotropic genes and that the behavioral phenotype manifests itself as an emergent property of such networks. Such networks are exquisitely sensitive to genetic background and sex effects. This review describes how Drosophila can serve as a model for uncovering fundamental principles of the genetic architecture of behavior.
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Affiliation(s)
- Robert R H Anholt
- WM Keck Center for Behavioral Biology and Departments of Zoology and Genetics, North Carolina State University, Raleigh, NC 27695-7617, USA.
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