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Rathore S, Stahl A, Benoit JB, Buschbeck EK. Exploring the molecular makeup of support cells in insect camera eyes. BMC Genomics 2023; 24:702. [PMID: 37993800 PMCID: PMC10664524 DOI: 10.1186/s12864-023-09804-5] [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: 07/20/2023] [Accepted: 11/13/2023] [Indexed: 11/24/2023] Open
Abstract
Animals typically have either compound eyes, or camera-type eyes, both of which have evolved repeatedly in the animal kingdom. Both eye types include two important kinds of cells: photoreceptor cells, which can be excited by light, and non-neuronal support cells (SupCs), which provide essential support to photoreceptors. At the molecular level deeply conserved genes that relate to the differentiation of photoreceptor cells have fueled a discussion on whether or not a shared evolutionary origin might be considered for this cell type. In contrast, only a handful of studies, primarily on the compound eyes of Drosophila melanogaster, have demonstrated molecular similarities in SupCs. D. melanogaster SupCs (Semper cells and primary pigment cells) are specialized eye glia that share several molecular similarities with certain vertebrate eye glia, including Müller glia. This led us to question if there could be conserved molecular signatures of SupCs, even in functionally different eyes such as the image-forming larval camera eyes of the sunburst diving beetle Thermonectus marmoratus. To investigate this possibility, we used an in-depth comparative whole-tissue transcriptomics approach. Specifically, we dissected the larval principal camera eyes into SupC- and retina-containing regions and generated the respective transcriptomes. Our analysis revealed several common features of SupCs including enrichment of genes that are important for glial function (e.g. gap junction proteins such as innexin 3), glycogen production (glycogenin), and energy metabolism (glutamine synthetase 1 and 2). To evaluate similarities, we compared our transcriptomes with those of fly (Semper cells) and vertebrate (Müller glia) eye glia as well as respective retinas. T. marmoratus SupCs were found to have distinct genetic overlap with both fly and vertebrate eye glia. These results suggest that T. marmoratus SupCs are a form of glia, and like photoreceptors, may be deeply conserved.
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Affiliation(s)
- Shubham Rathore
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, USA.
- Section on Light and Circadian Rhythms (SLCR), National Institute of Mental Health, NIH, Bethesda, MD, 20892, USA.
| | - Aaron Stahl
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, USA
- Department of Neuroscience and Pharmacology, University of Iowa Carver College of Medicine, Iowa City, IA, USA
| | - Joshua B Benoit
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, USA
| | - Elke K Buschbeck
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, USA.
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2
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Rathore S, Stahl A, Benoit JB, Buschbeck EK. Exploring the molecular makeup of support cells in insect camera eyes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.19.549729. [PMID: 37503285 PMCID: PMC10370194 DOI: 10.1101/2023.07.19.549729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Animals generally have either compound eyes, which have evolved repeatedly in different invertebrates, or camera eyes, which have evolved many times across the animal kingdom. Both eye types include two important kinds of cells: photoreceptor cells, which can be excited by light, and non-neuronal support cells (SupCs), which provide essential support to photoreceptors. Despite many examples of convergence in eye evolution, similarities in the gross developmental plan and molecular signatures have been discovered, even between phylogenetically distant and functionally different eye types. For this reason, a shared evolutionary origin has been considered for photoreceptors. In contrast, only a handful of studies, primarily on the compound eyes of Drosophila melanogaster , have demonstrated molecular similarities in SupCs. D. melanogaster SupCs (Semper cells and primary pigment cells) are specialized eye glia that share several molecular similarities with certain vertebrate eye glia, including Müller glia. This led us to speculate whether there are conserved molecular signatures of SupCs, even in functionally different eyes such as the image-forming larval camera eyes of the sunburst diving beetle Thermonectus marmoratus . To investigate this possibility, we used an in-depth comparative whole-tissue transcriptomics approach. Specifically, we dissected the larval principal camera eyes into SupC- and retina-containing regions and generated the respective transcriptomes. Our analysis revealed several conserved features of SupCs including enrichment of genes that are important for glial function (e.g. gap junction proteins such as innexin 3), glycogen production (glycogenin), and energy metabolism (glutamine synthetase 1 and 2). To evaluate the extent of conservation, we compared our transcriptomes with those of fly (Semper cells) and vertebrate (Müller glia) eye glia as well as respective retinas. T. marmoratus SupCs were found to have distinct genetic overlap with both fly and vertebrate eye glia. These results provide molecular evidence for the deep conservation of SupCs in addition to photoreceptor cells, raising essential questions about the evolutionary origin of eye-specific glia in animals.
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Au DD, Liu JC, Park SJ, Nguyen TH, Dimalanta M, Foden AJ, Holmes TC. Drosophila photoreceptor systems converge in arousal neurons and confer light responsive robustness. Front Neurosci 2023; 17:1160353. [PMID: 37274190 PMCID: PMC10235467 DOI: 10.3389/fnins.2023.1160353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 05/05/2023] [Indexed: 06/06/2023] Open
Abstract
Lateral ventral neurons (LNvs) in the fly circadian neural circuit mediate behaviors other than clock resetting, including light-activated acute arousal. Converging sensory inputs often confer functional redundancy. The LNvs have three distinct light input pathways: (1) cell autonomously expressed cryptochrome (CRY), (2) rhodopsin 7 (Rh7), and (3) synaptic inputs from the eyes and other external photoreceptors that express opsins and CRY. We explored the relative photoelectrical and behavioral input contributions of these three photoreceptor systems to determine their functional impact in flies. Patch-clamp electrophysiology measuring light evoked firing frequency (FF) was performed on large LNvs (l-LNvs) in response to UV (365 nm), violet (405 nm), blue (450 nm), or red (635 nm) LED light stimulation, testing controls versus mutants that lack photoreceptor inputs gl60j, cry-null, rh7-null, and double mutant gl60j-cry-null flies. For UV, violet, and blue short wavelength light inputs, all photoreceptor mutants show significantly attenuated action potential FF responses measured in the l-LNv. In contrast, red light FF responses are only significantly attenuated in double mutant gl60j-cry-null flies. We used a light-pulse arousal assay to compare behavioral responses to UV, violet, blue and red light of control and light input mutants, measuring the awakening arousal response of flies during subjective nighttime at two different intensities to capture potential threshold differences (10 and 400 μW/cm2). The light arousal behavioral results are similar to the electrophysiological results, showing significant attenuation of behavioral light responses for mutants compared to control. These results show that the different LNv convergent photoreceptor systems are integrated and together confer functional redundancy for light evoked behavioral arousal.
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Affiliation(s)
- David D. Au
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, United States
| | - Jenny C. Liu
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, United States
| | - Soo Jee Park
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, United States
| | - Thanh H. Nguyen
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, United States
| | - Mia Dimalanta
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, United States
| | - Alexander J. Foden
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, United States
| | - Todd C. Holmes
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, United States
- Center for Neural Circuit Mapping, School of Medicine, University of California, Irvine, Irvine, CA, United States
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4
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Palmateer CM, Artikis C, Brovero SG, Friedman B, Gresham A, Arbeitman MN. Single-cell transcriptome profiles of Drosophila fruitless-expressing neurons from both sexes. eLife 2023; 12:e78511. [PMID: 36724009 PMCID: PMC9891730 DOI: 10.7554/elife.78511] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 01/08/2023] [Indexed: 02/02/2023] Open
Abstract
Drosophila melanogaster reproductive behaviors are orchestrated by fruitless neurons. We performed single-cell RNA-sequencing on pupal neurons that produce sex-specifically spliced fru transcripts, the fru P1-expressing neurons. Uniform Manifold Approximation and Projection (UMAP) with clustering generates an atlas containing 113 clusters. While the male and female neurons overlap in UMAP space, more than half the clusters have sex differences in neuron number, and nearly all clusters display sex-differential expression. Based on an examination of enriched marker genes, we annotate clusters as circadian clock neurons, mushroom body Kenyon cell neurons, neurotransmitter- and/or neuropeptide-producing, and those that express doublesex. Marker gene analyses also show that genes that encode members of the immunoglobulin superfamily of cell adhesion molecules, transcription factors, neuropeptides, neuropeptide receptors, and Wnts have unique patterns of enriched expression across the clusters. In vivo spatial gene expression links to the clusters are examined. A functional analysis of fru P1 circadian neurons shows they have dimorphic roles in activity and period length. Given that most clusters are comprised of male and female neurons indicates that the sexes have fru P1 neurons with common gene expression programs. Sex-specific expression is overlaid on this program, to build the potential for vastly different sex-specific behaviors.
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Affiliation(s)
- Colleen M Palmateer
- Department of Biomedical Sciences, Florida State University, College of MedicineTallahasseeUnited States
| | - Catherina Artikis
- Department of Biomedical Sciences, Florida State University, College of MedicineTallahasseeUnited States
| | - Savannah G Brovero
- Department of Biomedical Sciences, Florida State University, College of MedicineTallahasseeUnited States
| | - Benjamin Friedman
- Department of Biomedical Sciences, Florida State University, College of MedicineTallahasseeUnited States
| | - Alexis Gresham
- Department of Biomedical Sciences, Florida State University, College of MedicineTallahasseeUnited States
| | - Michelle N Arbeitman
- Department of Biomedical Sciences, Florida State University, College of MedicineTallahasseeUnited States
- Program of Neuroscience, Florida State UniversityTallahasseeUnited States
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Damulewicz M, Tyszka A, Pyza E. Light exposure during development affects physiology of adults in Drosophila melanogaster. Front Physiol 2022; 13:1008154. [PMID: 36505068 PMCID: PMC9732085 DOI: 10.3389/fphys.2022.1008154] [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: 07/31/2022] [Accepted: 11/14/2022] [Indexed: 11/27/2022] Open
Abstract
Light is one of most important factors synchronizing organisms to day/night cycles in the environment. In Drosophila it is received through compound eyes, Hofbauer-Buchner eyelet, ocelli, using phospholipase C-dependent phototransduction and by deep brain photoreceptors, like Cryptochrome. Even a single light pulse during early life induces larval-time memory, which synchronizes the circadian clock and maintains daily rhythms in adult flies. In this study we investigated several processes in adult flies after maintaining their embryos, larvae and pupae in constant darkness (DD) until eclosion. We found that the lack of external light during development affects sleep time, by reduction of night sleep, and in effect shift to the daytime. However, disruption of internal CRY- dependent photoreception annuls this effect. We also observed changes in the expression of genes encoding neurotransmitters and their receptors between flies kept in different light regime. In addition, the lack of light during development results in decreasing size of mushroom bodies, involved in sleep regulation. Taking together, our results show that presence of light during early life plays a key role in brain development and affects adult behavior.
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Dopamine and GPCR-mediated modulation of DN1 clock neurons gates the circadian timing of sleep. Proc Natl Acad Sci U S A 2022; 119:e2206066119. [PMID: 35969763 PMCID: PMC9407311 DOI: 10.1073/pnas.2206066119] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Neuromodulation is essential for adaptive animal behaviors among other physiological processes. It is essential to reliably manipulate neuromodulator pathways to understand their functions in animal physiology. In this study, we generated a CRISPR-Cas9-based guide library to target every G-Protein Coupled Receptor (GPCR) in the Drosophila genome and applied it to the well-studied clock neuron network. Notably, these GPCRs are highly enriched and differentially expressed in this small network, making it an ideal candidate to investigate their function. We cell-type specifically mutated GPCRs highly efficiently with no background gene editing detected. Applying this strategy to a specific node of the clock network revealed a role for dopamine in prolonging daytime sleep, suggesting network-specific functions of dopamine receptors in sleep-wake regulation. The metronome-like circadian regulation of sleep timing must still adapt to an uncertain environment. Recent studies in Drosophila indicate that neuromodulation not only plays a key role in clock neuron synchronization but also affects interactions between the clock network and brain sleep centers. We show here that the targets of neuromodulators, G Protein Coupled Receptors (GPCRs), are highly enriched in the fly brain circadian clock network. Single-cell sequencing indicates that they are not only enriched but also differentially expressed and contribute to clock neuron identity. We generated a comprehensive guide library to mutagenize individual GPCRs in specific neurons and verified the strategy by introducing a targeted sequencing approach. Combined with a behavioral screen, the mutagenesis strategy revealed a role of dopamine in sleep regulation by identifying two dopamine receptors and a clock neuron subpopulation that gate the timing of sleep.
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7
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Nave C, Roberts L, Hwu P, Estrella JD, Vo TC, Nguyen TH, Bui TT, Rindner DJ, Pervolarakis N, Shaw PJ, Leise TL, Holmes TC. Weekend Light Shifts Evoke Persistent Drosophila Circadian Neural Network Desynchrony. J Neurosci 2021; 41:5173-5189. [PMID: 33931552 PMCID: PMC8211545 DOI: 10.1523/jneurosci.3074-19.2021] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 04/13/2021] [Accepted: 04/15/2021] [Indexed: 11/21/2022] Open
Abstract
We developed a method for single-cell resolution longitudinal bioluminescence imaging of PERIOD (PER) protein and TIMELESS (TIM) oscillations in cultured male adult Drosophila brains that captures circadian circuit-wide cycling under simulated day/night cycles. Light input analysis confirms that CRYPTOCHROME (CRY) is the primary circadian photoreceptor and mediates clock disruption by constant light (LL), and that eye light input is redundant to CRY; 3-h light phase delays (Friday) followed by 3-h light phase advances (Monday morning) simulate the common practice of staying up later at night on weekends, sleeping in later on weekend days then returning to standard schedule Monday morning [weekend light shift (WLS)]. PER and TIM oscillations are highly synchronous across all major circadian neuronal subgroups in unshifted light schedules for 11 d. In contrast, WLS significantly dampens PER oscillator synchrony and rhythmicity in most circadian neurons during and after exposure. Lateral ventral neuron (LNv) oscillations are the first to desynchronize in WLS and the last to resynchronize in WLS. Surprisingly, the dorsal neuron group-3 (DN3s) increase their within-group synchrony in response to WLS. In vivo, WLS induces transient defects in sleep stability, learning, and memory that temporally coincide with circuit desynchrony. Our findings suggest that WLS schedules disrupt circuit-wide circadian neuronal oscillator synchrony for much of the week, thus leading to observed behavioral defects in sleep, learning, and memory.
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Affiliation(s)
- Ceazar Nave
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697
| | - Logan Roberts
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697
| | - Patrick Hwu
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697
| | - Jerson D Estrella
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697
| | - Thanh C Vo
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697
| | - Thanh H Nguyen
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697
| | - Tony Thai Bui
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697
| | - Daniel J Rindner
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697
| | - Nicholas Pervolarakis
- Center for Complex Biological Systems, University of California, Irvine, Irvine, California 92697
| | - Paul J Shaw
- Department of Anatomy and Neurobiology, Washington University in St. Louis, St. Louis, Missouri 63110
| | - Tanya L Leise
- Department of Mathematics and Statistics, Amherst College, Amherst, Massachusetts 01002
| | - Todd C Holmes
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697
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Ma D, Przybylski D, Abruzzi KC, Schlichting M, Li Q, Long X, Rosbash M. A transcriptomic taxonomy of Drosophila circadian neurons around the clock. eLife 2021; 10:63056. [PMID: 33438579 PMCID: PMC7837698 DOI: 10.7554/elife.63056] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Accepted: 01/11/2021] [Indexed: 01/19/2023] Open
Abstract
Many different functions are regulated by circadian rhythms, including those orchestrated by discrete clock neurons within animal brains. To comprehensively characterize and assign cell identity to the 75 pairs of Drosophila circadian neurons, we optimized a single-cell RNA sequencing method and assayed clock neuron gene expression at different times of day. The data identify at least 17 clock neuron categories with striking spatial regulation of gene expression. Transcription factor regulation is prominent and likely contributes to the robust circadian oscillation of many transcripts, including those that encode cell-surface proteins previously shown to be important for cell recognition and synapse formation during development. The many other clock-regulated genes also constitute an important resource for future mechanistic and functional studies between clock neurons and/or for temporal signaling to circuits elsewhere in the fly brain.
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Affiliation(s)
- Dingbang Ma
- Howard Hughes Medical Institute, Brandeis University, Waltham, United States
| | - Dariusz Przybylski
- Howard Hughes Medical Institute, Brandeis University, Waltham, United States
| | - Katharine C Abruzzi
- Howard Hughes Medical Institute, Brandeis University, Waltham, United States
| | | | - Qunlong Li
- Howard Hughes Medical Institute, Brandeis University, Waltham, United States
| | - Xi Long
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, United States
| | - Michael Rosbash
- Howard Hughes Medical Institute, Brandeis University, Waltham, United States
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Mazzotta GM, Damulewicz M, Cusumano P. Better Sleep at Night: How Light Influences Sleep in Drosophila. Front Physiol 2020; 11:997. [PMID: 33013437 PMCID: PMC7498665 DOI: 10.3389/fphys.2020.00997] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 07/22/2020] [Indexed: 01/25/2023] Open
Abstract
Sleep-like states have been described in Drosophila and the mechanisms and factors that generate and define sleep-wake profiles in this model organism are being thoroughly investigated. Sleep is controlled by both circadian and homeostatic mechanisms, and environmental factors such as light, temperature, and social stimuli are fundamental in shaping and confining sleep episodes into the correct time of the day. Among environmental cues, light seems to have a prominent function in modulating the timing of sleep during the 24 h and, in this review, we will discuss the role of light inputs in modulating the distribution of the fly sleep-wake cycles. This phenomenon is of growing interest in the modern society, where artificial light exposure during the night is a common trait, opening the possibility to study Drosophila as a model organism for investigating shift-work disorders.
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Affiliation(s)
| | - Milena Damulewicz
- Department of Cell Biology and Imaging, Jagiellonian University, Kraków, Poland
| | - Paola Cusumano
- Department of Biology, University of Padova, Padua, Italy
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10
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Ogueta M, Hardie RC, Stanewsky R. Light Sampling via Throttled Visual Phototransduction Robustly Synchronizes the Drosophila Circadian Clock. Curr Biol 2020; 30:2551-2563.e3. [PMID: 32502413 DOI: 10.1016/j.cub.2020.04.067] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 04/07/2020] [Accepted: 04/24/2020] [Indexed: 01/19/2023]
Abstract
The daily changes of light and dark exemplify a prominent cue for the synchronization of circadian clocks with the environment. The match between external and internal time is crucial for the fitness of organisms, and desynchronization has been linked to numerous physical and mental health problems. Organisms therefore developed complex and not fully understood mechanisms to synchronize their circadian clock to light. In mammals and in Drosophila, both the visual system and non-image-forming photoreceptors contribute to circadian clock resetting. In Drosophila, light-dependent degradation of the clock protein TIMELESS by the blue light photoreceptor Cryptochrome is considered the main mechanism for clock synchronization, although the visual system also contributes. To better understand the visual system contribution, we generated a genetic variant exhibiting extremely slow phototransduction kinetics, yet normal sensitivity. In this variant, the visual system is able to contribute its full share to circadian clock entrainment, both with regard to behavioral and molecular light synchronization. This function depends on an alternative phospholipase C-β enzyme, encoded by PLC21C, presumably playing a dedicated role in clock resetting. We show that this pathway requires the ubiquitin ligase CULLIN-3, possibly mediating CRY-independent degradation of TIMELESS during light:dark cycles. Our results suggest that the PLC21C-mediated contribution to circadian clock entrainment operates on a drastically slower timescale compared with fast, norpA-dependent visual phototransduction. Our findings are therefore consistent with the general idea that the visual system samples light over prolonged periods of time (h) in order to reliably synchronize their internal clocks with the external time.
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Affiliation(s)
- Maite Ogueta
- Institute of Neuro and Behavioral Biology, Westfälische Wilhelms University, 48149 Münster, Germany
| | - Roger C Hardie
- Department of Physiology, Development, and Neuroscience, Cambridge University, Cambridge CB2 3EG, UK
| | - Ralf Stanewsky
- Institute of Neuro and Behavioral Biology, Westfälische Wilhelms University, 48149 Münster, Germany.
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11
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de Azevedo RVDM, Hansen C, Chen KF, Rosato E, Kyriacou CP. Disrupted Glutamate Signaling in Drosophila Generates Locomotor Rhythms in Constant Light. Front Physiol 2020; 11:145. [PMID: 32210832 PMCID: PMC7069353 DOI: 10.3389/fphys.2020.00145] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 02/11/2020] [Indexed: 01/23/2023] Open
Abstract
We have used the Cambridge Protein Trap resource (CPTI) to screen for flies whose locomotor rhythms are rhythmic in constant light (LL) as a means of identifying circadian photoreception genes. From the screen of ∼150 CPTI lines, we obtained seven hits, two of which targeted the glutamate pathway, Got1 (Glutamate oxaloacetate transaminase 1) and Gs2 (Glutamine synthetase 2). We focused on these by employing available mutants and observed that variants of these genes also showed high levels of LL rhythmicity compared with controls. It was also clear that the genetic background was important with a strong interaction observed with the common and naturally occurring timeless (tim) polymorphisms, ls-tim and s-tim. The less circadian photosensitive ls-tim allele generated high levels of LL rhythmicity in combination with Got1 or Gs2, even though ls-tim and s-tim alleles do not, by themselves, generate the LL phenotype. The use of dsRNAi for both genes as well as for Gad (Glutamic acid decarboxylase) and the metabotropic glutamate receptor DmGluRA driven by clock gene promoters also revealed high levels of LL rhythmicity compared to controls. It is clear that the glutamate pathway is heavily implicated in circadian photoreception. TIM levels in Got1 and Gs2 mutants cycled and were more abundant than in controls under LL. Got1 but not Gs2 mutants showed diminished phase shifts to 10 min light pulses. Neurogenetic dissection of the LL rhythmic phenotype using the gal4/gal80 UAS bipartite system suggested that the more dorsal CRY-negative clock neurons, DNs and LNds were responsible for the LL phenotype. Immunocytochemistry using the CPTI YFP tagged insertions for the two genes revealed that the DN1s but not the DN2 and DN3s expressed Got1 and Gs2, but expression was also observed in the lateral neurons, the LNds and s-LNvs. Expression of both genes was also found in neuroglia. However, downregulation of glial Gs2 and Got1 using repo-gal4 did not generate high levels of LL rhythmicity, so it is unlikely that this phenotype is mediated by glial expression. Our results suggest a model whereby the DN1s and possibly CRY-negative LNds use glutamate signaling to supress the pacemaker s-LNvs in LL.
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Affiliation(s)
| | - Celia Hansen
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Ko-Fan Chen
- School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - 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
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12
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Helfrich-Förster C. Light input pathways to the circadian clock of insects with an emphasis on the fruit fly Drosophila melanogaster. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2019; 206:259-272. [PMID: 31691095 PMCID: PMC7069913 DOI: 10.1007/s00359-019-01379-5] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 10/19/2019] [Accepted: 10/26/2019] [Indexed: 12/26/2022]
Abstract
Light is the most important Zeitgeber for entraining animal activity rhythms to the 24-h day. In all animals, the eyes are the main visual organs that are not only responsible for motion and colour (image) vision, but also transfer light information to the circadian clock in the brain. The way in which light entrains the circadian clock appears, however, variable in different species. As do vertebrates, insects possess extraretinal photoreceptors in addition to their eyes (and ocelli) that are sometimes located close to (underneath) the eyes, but sometimes even in the central brain. These extraretinal photoreceptors contribute to entrainment of their circadian clocks to different degrees. The fruit fly Drosophila melanogaster is special, because it expresses the blue light-sensitive cryptochrome (CRY) directly in its circadian clock neurons, and CRY is usually regarded as the fly’s main circadian photoreceptor. Nevertheless, recent studies show that the retinal and extraretinal eyes transfer light information to almost every clock neuron and that the eyes are similarly important for entraining the fly’s activity rhythm as in other insects, or more generally spoken in other animals. Here, I compare the light input pathways between selected insect species with a focus on Drosophila’s special case.
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13
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Abstract
CRYPTOCHROMES (CRYs) are structurally related to ultraviolet (UV)/blue-sensitive DNA repair enzymes called photolyases but lack the ability to repair pyrimidine dimers generated by UV exposure. First identified in plants, CRYs have proven to be involved in light detection and various light-dependent processes in a broad range of organisms. In Drosophila, CRY's best understood role is the cell-autonomous synchronization of circadian clocks. However, CRY also contributes to the amplitude of circadian oscillations in a light-independent manner, controls arousal and UV avoidance, influences visual photoreception, and plays a key role in magnetic field detection. Here, we review our current understanding of the mechanisms underlying CRY's various circadian and noncircadian functions in fruit flies.
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Affiliation(s)
- Lauren E Foley
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Patrick Emery
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts
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Schlichting M, Weidner P, Diaz M, Menegazzi P, Dalla Benetta E, Helfrich-Förster C, Rosbash M. Light-Mediated Circuit Switching in the Drosophila Neuronal Clock Network. Curr Biol 2019; 29:3266-3276.e3. [PMID: 31564496 DOI: 10.1016/j.cub.2019.08.033] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 06/28/2019] [Accepted: 08/13/2019] [Indexed: 12/16/2022]
Abstract
The circadian clock is a timekeeper but also helps adapt physiology to the outside world. This is because an essential feature of clocks is their ability to adjust (entrain) to the environment, with light being the most important signal. Whereas cryptochrome-mediated entrainment is well understood in Drosophila, integration of light information via the visual system lacks a neuronal or molecular mechanism. Here, we show that a single photoreceptor subtype is essential for long-day adaptation. These cells activate key circadian neurons, namely the large ventral-lateral neurons (lLNvs), which release the neuropeptide pigment-dispersing factor (PDF). RNAi and rescue experiments show that PDF from these cells is necessary and sufficient for delaying the timing of the evening (E) activity in long-day conditions. This contrasts to PDF that derives from the small ventral-lateral neurons (sLNvs), which are essential for constant darkness (DD) rhythmicity. Using a cell-specific CRISPR/Cas9 assay, we show that lLNv-derived PDF directly interacts with neurons important for E activity timing. Interestingly, this pathway is specific for long-day adaptation and appears to be dispensable in equinox or DD conditions. The results therefore indicate that external cues cause a rearrangement of neuronal hierarchy, which contributes to behavioral plasticity.
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Affiliation(s)
- Matthias Schlichting
- Howard Hughes Medical Institute and Department of Biology, Brandeis University, Waltham, MA 02454, USA.
| | - Patrick Weidner
- Howard Hughes Medical Institute and Department of Biology, Brandeis University, Waltham, MA 02454, USA; Department for Neurobiology and Genetics, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Madelen Diaz
- Howard Hughes Medical Institute and Department of Biology, Brandeis University, Waltham, MA 02454, USA
| | - Pamela Menegazzi
- Department for Neurobiology and Genetics, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Elena Dalla Benetta
- Department for Neurobiology and Genetics, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | | | - Michael Rosbash
- Howard Hughes Medical Institute and Department of Biology, Brandeis University, Waltham, MA 02454, USA
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15
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Daytime colour preference in Drosophila depends on the circadian clock and TRP channels. Nature 2019; 574:108-111. [DOI: 10.1038/s41586-019-1571-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2017] [Accepted: 08/28/2019] [Indexed: 11/08/2022]
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16
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Alejevski F, Saint-Charles A, Michard-Vanhée C, Martin B, Galant S, Vasiliauskas D, Rouyer F. The HisCl1 histamine receptor acts in photoreceptors to synchronize Drosophila behavioral rhythms with light-dark cycles. Nat Commun 2019; 10:252. [PMID: 30651542 PMCID: PMC6335465 DOI: 10.1038/s41467-018-08116-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 12/19/2018] [Indexed: 01/09/2023] Open
Abstract
In Drosophila, the clock that controls rest-activity rhythms synchronizes with light-dark cycles through either the blue-light sensitive cryptochrome (Cry) located in most clock neurons, or rhodopsin-expressing histaminergic photoreceptors. Here we show that, in the absence of Cry, each of the two histamine receptors Ort and HisCl1 contribute to entrain the clock whereas no entrainment occurs in the absence of the two receptors. In contrast to Ort, HisCl1 does not restore entrainment when expressed in the optic lobe interneurons. Indeed, HisCl1 is expressed in wild-type photoreceptors and entrainment is strongly impaired in flies with photoreceptors mutant for HisCl1. Rescuing HisCl1 expression in the Rh6-expressing photoreceptors restores entrainment but it does not in other photoreceptors, which send histaminergic inputs to Rh6-expressing photoreceptors. Our results thus show that Rh6-expressing neurons contribute to circadian entrainment as both photoreceptors and interneurons, recalling the dual function of melanopsin-expressing ganglion cells in the mammalian retina.
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Affiliation(s)
- Faredin Alejevski
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190, Gif-sur-Yvette, France
| | - Alexandra Saint-Charles
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190, Gif-sur-Yvette, France
- Institut de la Vision, Univ. P. & M. Curie, INSERM, CNRS, Sorbonne Université, Paris, 75012, France
| | - Christine Michard-Vanhée
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190, Gif-sur-Yvette, France
| | - Béatrice Martin
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190, Gif-sur-Yvette, France
| | - Sonya Galant
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190, Gif-sur-Yvette, France
| | - Daniel Vasiliauskas
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190, Gif-sur-Yvette, France
| | - François Rouyer
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190, Gif-sur-Yvette, France.
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17
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Senthilan PR, Grebler R, Reinhard N, Rieger D, Helfrich-Förster C. Role of Rhodopsins as Circadian Photoreceptors in the Drosophila melanogaster. BIOLOGY 2019; 8:biology8010006. [PMID: 30634679 PMCID: PMC6466219 DOI: 10.3390/biology8010006] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 12/14/2018] [Accepted: 01/04/2019] [Indexed: 12/19/2022]
Abstract
Light profoundly affects the circadian clock and the activity levels of animals. Along with the systematic changes in intensity and spectral composition, over the 24-h day, light shows considerable irregular fluctuations (noise). Using light as the Zeitgeber for the circadian clock is, therefore, a complex task and this might explain why animals utilize multiple photoreceptors to entrain their circadian clock. The fruit fly Drosophila melanogaster possesses light-sensitive Cryptochrome and seven Rhodopsins that all contribute to light detection. We review the role of Rhodopsins in circadian entrainment, and of direct light-effects on the activity, with a special emphasis on the newly discovered Rhodopsin 7 (Rh7). We present evidence that Rhodopsin 6 in receptor cells 8 of the compound eyes, as well as in the extra retinal Hofbauer-Buchner eyelets, plays a major role in entraining the fly’s circadian clock with an appropriate phase-to-light–dark cycles. We discuss recent contradictory findings regarding Rhodopsin 7 and report original data that support its role in the compound eyes and in the brain. While Rhodopsin 7 in the brain appears to have a minor role in entrainment, in the compound eyes it seems crucial for fine-tuning light sensitivity to prevent overshooting responses to bright light.
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Affiliation(s)
- Pingkalai R Senthilan
- Neurobiology & Genetics, Theodor-Boveri Institute, Biocenter, Julius-Maximilians University Würzburg, Am Hubland, 97074 Würzburg, Germany.
| | - Rudi Grebler
- Neurobiology & Genetics, Theodor-Boveri Institute, Biocenter, Julius-Maximilians University Würzburg, Am Hubland, 97074 Würzburg, Germany.
| | - Nils Reinhard
- Neurobiology & Genetics, Theodor-Boveri Institute, Biocenter, Julius-Maximilians University Würzburg, Am Hubland, 97074 Würzburg, Germany.
| | - Dirk Rieger
- Neurobiology & Genetics, Theodor-Boveri Institute, Biocenter, Julius-Maximilians University Würzburg, Am Hubland, 97074 Würzburg, Germany.
| | - Charlotte Helfrich-Förster
- Neurobiology & Genetics, Theodor-Boveri Institute, Biocenter, Julius-Maximilians University Würzburg, Am Hubland, 97074 Würzburg, Germany.
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18
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Responses to Intermittent Light Stimulation Late in the Night Phase Before Dawn. Clocks Sleep 2018; 1:26-41. [PMID: 33089153 PMCID: PMC7509681 DOI: 10.3390/clockssleep1010004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 09/26/2018] [Indexed: 12/04/2022] Open
Abstract
The circadian clock is comprised of two oscillators that independently track sunset (evening) and sunrise (morning), though little is known about how light responses differ in each. Here, we quantified the morning oscillator’s responses to 19 separate pulse trains, collecting observations from over 1300 Drosophila at ZT23. Our results show that the advances in activity onset produced by these protocols depended on the tempo of light administration even when total exposure was conserved across a 15-min window. Moreover, patterns of stimulation previously shown to optimize the evening oscillator’s delay resetting at ZT13 (an hour after dusk) were equally effective for the M oscillator at ZT23 (an hour before dawn), though the morning oscillator was by comparison more photosensitive and could benefit from a greater number of fractionation strategies that better converted light into phase-shifting drive. These data continue to build the case that the reading frames for the pacemaker’s time-of-day estimates at dusk and dawn are not uniform and suggest that the “photologic” for the evening versus morning oscillator’s resetting might be dissociable.
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19
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Ogueta M, Hardie RC, Stanewsky R. Non-canonical Phototransduction Mediates Synchronization of the Drosophila melanogaster Circadian Clock and Retinal Light Responses. Curr Biol 2018; 28:1725-1735.e3. [PMID: 29779871 PMCID: PMC5988559 DOI: 10.1016/j.cub.2018.04.016] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 03/23/2018] [Accepted: 04/04/2018] [Indexed: 12/28/2022]
Abstract
The daily light-dark cycles represent a key signal for synchronizing circadian clocks. Both insects and mammals possess dedicated "circadian" photoreceptors but also utilize the visual system for clock resetting. In Drosophila, circadian clock resetting is achieved by the blue-light photoreceptor cryptochrome (CRY), which is expressed within subsets of the brain clock neurons. In addition, rhodopsin-expressing photoreceptor cells contribute to light synchronization. Light resets the molecular clock by CRY-dependent degradation of the clock protein Timeless (TIM), although in specific subsets of key circadian pacemaker neurons, including the small ventral lateral neurons (s-LNvs), TIM and Period (PER) oscillations can be synchronized by light independent of CRY and canonical visual Rhodopsin phototransduction. Here, we show that at least three of the seven Drosophila rhodopsins can utilize an alternative transduction mechanism involving the same α-subunit of the heterotrimeric G protein operating in canonical visual phototransduction (Gq). Surprisingly, in mutants lacking the canonical phospholipase C-β (PLC-β) encoded by the no receptor potential A (norpA) gene, we uncovered a novel transduction pathway using a different PLC-β encoded by the Plc21C gene. This novel pathway is important for behavioral clock resetting to semi-natural light-dark cycles and mediates light-dependent molecular synchronization within the s-LNv clock neurons. The same pathway appears to be responsible for norpA-independent light responses in the compound eye. We show that Rhodopsin 5 (Rh5) and Rh6, present in the R8 subset of retinal photoreceptor cells, drive both the long-term circadian and rapid light responses in the eye.
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Affiliation(s)
- Maite Ogueta
- Institute of Neuro- and Behavioral Biology, Westfälische Wilhelms University, 48149 Münster, Germany
| | - Roger C Hardie
- Department of Physiology, Development, and Neuroscience, Cambridge University, Cambridge CB2 3DY, UK
| | - Ralf Stanewsky
- Institute of Neuro- and Behavioral Biology, Westfälische Wilhelms University, 48149 Münster, Germany.
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20
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Reflections on contributing to "big discoveries" about the fly clock: Our fortunate paths as post-docs with 2017 Nobel laureates Jeff Hall, Michael Rosbash, and Mike Young. Neurobiol Sleep Circadian Rhythms 2018; 5:58-67. [PMID: 31236512 PMCID: PMC6584674 DOI: 10.1016/j.nbscr.2018.02.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 02/23/2018] [Accepted: 02/23/2018] [Indexed: 11/20/2022] Open
Abstract
In the early 1980s Jeff Hall and Michael Rosbash at Brandeis University and Mike Young at Rockefeller University set out to isolate the period (per) gene, which was recovered in a revolutionary genetic screen by Ron Konopka and Seymour Benzer for mutants that altered circadian behavioral rhythms. Over the next 15 years the Hall, Rosbash and Young labs made a series of groundbreaking discoveries that defined the molecular timekeeping mechanism and formed the basis for them being awarded the 2017 Nobel Prize in Physiology or Medicine. Here the authors recount their experiences as post-docs in the Hall, Rosbash and Young labs from the mid-1980s to the mid-1990s, and provide a perspective of how basic research conducted on a simple model system during that era profoundly influenced the direction of the clocks field and established novel approaches that are now standard operating procedure for studying complex behavior. 2017 Nobel Prize awarded to Hall, Rosbash and Young for circadian clock mechanisms. Work on fruit flies in the 1980s and 1990s were key to deciphering clock mechanisms. Authors recount their experiences as postdocs in the Hall, Rosbash and Young labs. The broad impacts of basic research on fruit fly clock genes.
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21
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Grebler R, Kistenpfennig C, Rieger D, Bentrop J, Schneuwly S, Senthilan PR, Helfrich-Förster C. Drosophila Rhodopsin 7 can partially replace the structural role of Rhodopsin 1, but not its physiological function. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2017; 203:649-659. [PMID: 28500442 PMCID: PMC5537319 DOI: 10.1007/s00359-017-1182-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 05/03/2017] [Accepted: 05/05/2017] [Indexed: 11/25/2022]
Abstract
Rhodopsin 7 (Rh7), a new invertebrate Rhodopsin gene, was discovered in the genome of Drosophila melanogaster in 2000 and thought to encode for a functional Rhodopsin protein. Indeed, Rh7 exhibits most hallmarks of the known Rhodopsins, except for the G-protein-activating QAKK motif in the third cytoplasmic loop that is absent in Rh7. Here, we show that Rh7 can partially substitute Rh1 in the outer receptor cells (R1–6) for rhabdomere maintenance, but that it cannot activate the phototransduction cascade in these cells. This speaks against a role of Rh7 as photopigment in R1–6, but does not exclude that it works in the inner photoreceptor cells.
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Affiliation(s)
- Rudi Grebler
- Neurobiology and Genetics, Biocenter, Theodor Boveri Institute, University of Würzburg, 97074, Würzburg, Germany
| | - Christa Kistenpfennig
- Neurobiology and Genetics, Biocenter, Theodor Boveri Institute, University of Würzburg, 97074, Würzburg, Germany
- Oxitec Ltd, 71 Innovation Drive, Milton Park, Oxford, OX14 4RQ, UK
| | - Dirk Rieger
- Neurobiology and Genetics, Biocenter, Theodor Boveri Institute, University of Würzburg, 97074, Würzburg, Germany
| | - Joachim Bentrop
- Cell- and Neurobiology, Zoological Institute, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Stephan Schneuwly
- Developmental Biology, Institute of Zoology, University of Regensburg, Regensburg, Germany
| | - Pingkalai R Senthilan
- Neurobiology and Genetics, Biocenter, Theodor Boveri Institute, University of Würzburg, 97074, Würzburg, Germany
| | - Charlotte Helfrich-Förster
- Neurobiology and Genetics, Biocenter, Theodor Boveri Institute, University of Würzburg, 97074, Würzburg, Germany.
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