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2.
Front Cell Dev Biol ; 9: 595754, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33763414

RESUMO

Endogenous clocks enable organisms to adapt cellular processes, physiology, and behavior to daily variation in environmental conditions. Metabolic processes in cyanobacteria to humans are under the influence of the circadian clock, and dysregulation of the circadian clock causes metabolic disorders. In mouse and Drosophila, the circadian clock influences translation of factors involved in ribosome biogenesis and synchronizes protein synthesis. Notably, nutrition signals are mediated by the insulin receptor/target of rapamycin (InR/TOR) pathways to regulate cellular metabolism and growth. However, the role of the circadian clock in Drosophila brain development and the potential impact of clock impairment on neural circuit formation and function is less understood. Here we demonstrate that changes in light stimuli or disruption of the molecular circadian clock cause a defect in neural stem cell growth and proliferation. Moreover, we show that disturbed cell growth and proliferation are accompanied by reduced nucleolar size indicative of impaired ribosomal biogenesis. Further, we define that light and clock independently affect the InR/TOR growth regulatory pathway due to the effect on regulators of protein biosynthesis. Altogether, these data suggest that alterations in InR/TOR signaling induced by changes in light conditions or disruption of the molecular clock have an impact on growth and proliferation properties of neural stem cells in the developing Drosophila brain.

3.
BMC Genomics ; 21(1): 596, 2020 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-32862827

RESUMO

BACKGROUND: Most animals restrict their activity to a specific part of the day, being diurnal, nocturnal or crepuscular. The genetic basis underlying diurnal preference is largely unknown. Under laboratory conditions, Drosophila melanogaster is crepuscular, showing a bi-modal activity profile. However, a survey of strains derived from wild populations indicated that high variability among individuals exists, including flies that are nocturnal. RESULTS: Using a highly diverse population, we performed an artificial selection experiment, selecting flies with extreme diurnal or nocturnal preference. After 10 generations, we obtained highly diurnal and nocturnal strains. We used whole-genome expression analysis to identify differentially expressed genes in diurnal, nocturnal and crepuscular (control) flies. Other than one circadian clock gene (pdp1), most differentially expressed genes were associated with either clock output (pdf, to) or input (Rh3, Rh2, msn). This finding was congruent with behavioural experiments indicating that both light masking and the circadian pacemaker are involved in driving nocturnality. CONCLUSIONS: Our study demonstrates that genetic variation segregating in wild populations contributes to substantial variation in diurnal preference. We identified candidate genes associated with diurnality/nocturnality, while data emerging from our expression analysis and behavioural experiments suggest that both clock and clock-independent pathways are involved in shaping diurnal preference. The diurnal and nocturnal selection strains provide us with a unique opportunity to understand the genetic architecture of diurnal preference.


Assuntos
Relógios Circadianos , Drosophila melanogaster , Animais , Relógios Circadianos/genética , Ritmo Circadiano/genética , Drosophila melanogaster/genética , Atividade Motora
4.
Front Physiol ; 11: 229, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32273848

RESUMO

A major challenge for all organisms that live in temperate and subpolar regions is to adapt physiology and activity to different photoperiods. A long-standing model assumes that there are morning (M) and evening (E) oscillators with different photoreceptive properties that couple to dawn and dusk, respectively, and by this way adjust activity to the different photoperiods. In the fruit fly Drosophila melanogaster, M and E oscillators have been localized to specific circadian clock neurons in the brain. Here, we investigate under different photoperiods the activity pattern of flies expressing the clock protein PERIOD (PER) only in subsets of M and E oscillators. We found that all fly lines that expressed PER only in subsets of the clock neurons had difficulties to track the morning and evening in a wild-type manner. The lack of the E oscillators advanced M activity under short days, whereas the lack of the M oscillators delayed E activity under the same conditions. In addition, we found that flies expressing PER only in subsets of clock neurons showed higher activity levels at certain times of day or night, suggesting that M and E clock neurons might inhibit activity at specific moments throughout the 24 h. Altogether, we show that the proper interaction between all clock cells is important for adapting the flies' activity to different photoperiods and discuss our findings in the light of the current literature.

5.
Eur J Neurosci ; 51(1): 166-181, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-30269385

RESUMO

Life on earth is assumed to have developed in tropical regions that are characterized by regular 24 hr cycles in irradiance and temperature that remain the same throughout the seasons. All organisms developed circadian clocks that predict these environmental cycles and prepare the organisms in advance for them. A central question in chronobiology is how endogenous clocks changed in order to anticipate very different cyclical environmental conditions such as extremely short and long photoperiods existing close to the poles. Flies of the family Drosophilidae can be found all over the world-from the tropics to subarctic regions-making them unprecedented models for studying the evolutionary processes that underlie the adaptation of circadian clocks to different latitudes. This review summarizes our current understanding of these processes. We discuss evolutionary changes in the clock genes and in the clock network in the brain of different Drosophilids that may have caused behavioural adaptations to high latitudes.


Assuntos
Relógios Circadianos , Dípteros , Proteínas de Drosophila , Adaptação Fisiológica , Animais , Ritmo Circadiano , Fotoperíodo
6.
Curr Biol ; 29(22): 3928-3936.e3, 2019 11 18.
Artigo em Inglês | MEDLINE | ID: mdl-31679928

RESUMO

Nearly all organisms evolved endogenous self-sustained timekeeping mechanisms to track and anticipate cyclic changes in the environment. Circadian clocks, with a periodicity of about 24 h, allow animals to adapt to day-night cycles. Biological clocks are highly adaptive, but strong behavioral rhythms might be a disadvantage for adaptation to weakly rhythmic environments such as polar areas [1, 2]. Several high-latitude species, including Drosophila species, were found to be highly arrhythmic under constant conditions [3-6]. Furthermore, Drosophila species from subarctic regions can extend evening activity until dusk under long days. These traits depend on the clock network neurochemistry, and we previously proposed that high-latitude Drosophila species evolved specific clock adaptations to colonize polar regions [5, 7, 8]. We broadened our analysis to 3 species of the Chymomyza genus, which diverged circa 5 million years before the Drosophila radiation [9] and colonized both low and high latitudes [10, 11]. C. costata, pararufithorax, and procnemis, independently of their latitude of origin, possess the clock neuronal network of low-latitude Drosophila species, and their locomotor activity does not track dusk under long photoperiods. Nevertheless, the high-latitude C. costata becomes arrhythmic under constant darkness (DD), whereas the two low-latitude species remain rhythmic. Different mechanisms are behind the arrhythmicity in DD of C. costata and the high-latitude Drosophila ezoana, suggesting that the ability to maintain behavioral rhythms has been lost more than once during drosophilids' evolution and that it might indeed be an evolutionary adaptation for life at high latitudes.


Assuntos
Relógios Circadianos/genética , Ritmo Circadiano/fisiologia , Drosophilidae/fisiologia , Adaptação Fisiológica/fisiologia , Altitude , Animais , Relógios Circadianos/fisiologia , Criptocromos/fisiologia , Escuridão , Drosophila/fisiologia , Proteínas de Drosophila/metabolismo , Drosophilidae/genética , Locomoção/fisiologia , Atividade Motora/fisiologia , Neurônios/fisiologia , Fenótipo , Fotoperíodo
7.
Curr Biol ; 29(19): 3266-3276.e3, 2019 10 07.
Artigo em Inglês | MEDLINE | ID: mdl-31564496

RESUMO

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.


Assuntos
Relógios Circadianos/genética , Proteínas de Drosophila/genética , Drosophila melanogaster/fisiologia , Neurônios/fisiologia , Neuropeptídeos/genética , Animais , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/genética , Neuropeptídeos/metabolismo , Interferência de RNA
8.
J Neurosci ; 39(9): 1621-1630, 2019 02 27.
Artigo em Inglês | MEDLINE | ID: mdl-30606757

RESUMO

To provide organisms with a fitness advantage, circadian clocks have to react appropriately to changes in their environment. High-intensity (HI) light plays an essential role in the adaptation to hot summer days, which especially endanger insects of desiccation or prey visibility. Here, we show that solely increasing light intensity leads to an increased midday siesta in Drosophila behavior. Interestingly, this change is independent of the fly's circadian photoreceptor cryptochrome and is solely caused by a small visual organ, the Hofbauer-Buchner eyelets. Using receptor knock-downs, immunostaining, and recently developed calcium tools, we show that the eyelets activate key core clock neurons, namely the s-LNvs, at HI. This activation delays the decrease of PERIOD (PER) in the middle of the day and propagates to downstream target clock neurons that prolong the siesta. We show a new pathway for integrating light-intensity information into the clock network, suggesting new network properties and surprising parallels between Drosophila and the mammalian system.SIGNIFICANCE STATEMENT The ability of animals to adapt to their ever-changing environment plays an important role in their fitness. A key player in this adaptation is the circadian clock. For animals to predict the changes of day and night, they must constantly monitor, detect and incorporate changes in the environment. The appropriate incorporation and reaction to high-intensity (HI) light is of special importance for insects because they might suffer from desiccation during hot summer days. We show here that different photoreceptors have specialized functions to integrate low-intensity, medium-intensity, or HI light into the circadian system in Drosophila These results show surprising parallels to mammalian mechanisms, which also use different photoreceptor subtypes to respond to different light intensities.


Assuntos
Adaptação Fisiológica , Relógios Circadianos , Vias Visuais/fisiologia , Animais , Criptocromos/genética , Criptocromos/metabolismo , Drosophila , Neurônios/metabolismo , Neurônios/fisiologia , Proteínas Circadianas Period/genética , Proteínas Circadianas Period/metabolismo , Vias Visuais/metabolismo
9.
J Biol Rhythms ; 33(6): 602-613, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30203704

RESUMO

Recently, we reported differences in the expression pattern of the blue light-sensitive flavoprotein cryptochrome (CRY) and the neuropeptide pigment-dispersing factor (PDF) in the neuronal clock network of high-latitude Drosophila species, belonging to the Drosophila subgenus ( virilis-repleta radiation), compared with cosmopolitan D. melanogaster flies, belonging to the Sophophora subgenus. Alterations in rhythmic patterns of activity due to these differences might have adaptive significance for colonizing high-latitude habitats and, hence, adjusting to long photoperiods. Here, we show that these differing CRY/PDF expression patterns are only present in those species of the virilis-repleta radiation that colonized high latitudes. The cosmopolitan species D. mercatorum and D. hydei have a D. melanogaster-like clock network and behavior despite belonging to the virilis-repleta radiation. Similarly, 2 species of the holotropical Zaprionus genus, more closely related to the Drosophila subgenus than to the Sophophora subgenus, retain a D. melanogaster-like clock network and rhythmic behavior. We therefore suggest that the D. melanogaster-like clock network is the "ancestral fly clock phenotype" and that alterations in the CRY/PDF clock neurochemistry have allowed some species of the virilis-repleta radiation to colonize high-latitude environments.


Assuntos
Relógios Circadianos/fisiologia , Drosophila/genética , Drosophila/fisiologia , Animais , Encéfalo/fisiologia , Relógios Circadianos/genética , Ritmo Circadiano , Criptocromos/genética , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/genética , Drosophila melanogaster/fisiologia , Evolução Molecular , Geografia , Masculino , Neuropeptídeos/metabolismo , Fotoperíodo , Receptores Acoplados a Proteínas G/genética
10.
Sci Rep ; 8(1): 7006, 2018 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-29712926

RESUMO

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

11.
Front Mol Neurosci ; 11: 122, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29706866

RESUMO

Endogenous molecular circadian clocks drive daily rhythmic changes at the cellular, physiological, and behavioral level for adaptation to and anticipation of environmental signals. The core molecular system consists of autoregulatory feedback loops, where clock proteins inhibit their own transcription. A complex and not fully understood interplay of regulatory proteins influences activity, localization and stability of clock proteins to set the pace of the clock. This study focuses on the molecular function of Ribosomal S6 Kinase (RSK) in the Drosophila melanogaster circadian clock. Mutations in the human rsk2 gene cause Coffin-Lowry syndrome, which is associated with severe mental disabilities. Knock-out studies with Drosophila ortholog rsk uncovered functions in synaptic processes, axonal transport and adult behavior including associative learning and circadian activity. However, the molecular targets of RSK remain elusive. Our experiments provide evidence that RSK acts in the key pace maker neurons as a negative regulator of Shaggy (SGG) kinase activity, which in turn determines timely nuclear entry of the clock proteins Period and Timeless to close the negative feedback loop. Phosphorylation of serine 9 in SGG is mediated by the C-terminal kinase domain of RSK, which is in agreement with previous genetic studies of RSK in the circadian clock but argues against the prevailing view that only the N-terminal kinase domain of RSK proteins carries the effector function. Our data provide a mechanistic explanation how RSK influences the molecular clock and imply SGG S9 phosphorylation by RSK and other kinases as a convergence point for diverse cellular and external stimuli.

12.
J Biol Rhythms ; 33(3): 255-271, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29589522

RESUMO

The circadian clock of social insects has become a focal point of interest for research, as social insects show complex forms of timed behavior and organization within their colonies. These behaviors include brood care, nest maintenance, foraging, swarming, defense, and many other tasks, of which several require social synchronization and accurate timing. Ants of the genus Camponotus have been shown to display a variety of daily timed behaviors such as the emergence of males from the nest, foraging, and relocation of brood. Nevertheless, circadian rhythms of isolated individuals have been studied in few ant species, and the circadian clock network in the brain that governs such behaviors remains completely uncharacterized. Here we show that isolated minor workers of Camponotus floridanus exhibit temperature overcompensated free-running locomotor activity rhythms under constant darkness. Under light-dark cycles, most animals are active during day and night, with a slight preference for the night. On the neurobiological level, we show that distinct cell groups in the lateral and dorsal brain of minor workers of C. floridanus are immunostained with an antibody against the clock protein Period (PER) and a lateral group additionally with an antibody against the neuropeptide pigment-dispersing factor (PDF). PER abundance oscillates in a daily manner, and PDF-positive neurites invade most parts of the brain, suggesting that the PER/PDF-positive neurons are bona fide clock neurons that transfer rhythmic signals into the relevant brain areas controlling rhythmic behavior.


Assuntos
Formigas/fisiologia , Comportamento Animal , Relógios Circadianos , Neurônios/fisiologia , Fotoperíodo , Animais , Encéfalo/citologia , Encéfalo/fisiologia , Ritmo Circadiano/fisiologia , Locomoção , Masculino , Atividade Motora , Proteínas Circadianas Period/metabolismo
13.
Open Biol ; 8(1)2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29321240

RESUMO

Pigment-Dispersing Factor (PDF) is an important neuropeptide in the brain circadian network of Drosophila and other insects, but its role in bees in which the circadian clock influences complex behaviour is not well understood. We combined high-resolution neuroanatomical characterizations, quantification of PDF levels over the day and brain injections of synthetic PDF peptide to study the role of PDF in the honey bee Apis mellifera We show that PDF co-localizes with the clock protein Period (PER) in a cluster of laterally located neurons and that the widespread arborizations of these PER/PDF neurons are in close vicinity to other PER-positive cells (neurons and glia). PDF-immunostaining intensity oscillates in a diurnal and circadian manner with possible influences for age or worker task on synchrony of oscillations in different brain areas. Finally, PDF injection into the area between optic lobes and the central brain at the end of the subjective day produced a consistent trend of phase-delayed circadian rhythms in locomotor activity. Altogether, these results are consistent with the hypothesis that PDF is a neuromodulator that conveys circadian information from pacemaker cells to brain centres involved in diverse functions including locomotion, time memory and sun-compass orientation.


Assuntos
Encéfalo/metabolismo , Relógios Circadianos , Proteínas de Insetos/metabolismo , Neurônios/metabolismo , Neuropeptídeos/metabolismo , Animais , Abelhas , Encéfalo/citologia , Encéfalo/fisiologia , Locomoção , Neurônios/fisiologia , Proteínas Circadianas Period/metabolismo
14.
Sci Rep ; 8(1): 816, 2018 01 16.
Artigo em Inglês | MEDLINE | ID: mdl-29339768

RESUMO

The olive fruit fly, Bactrocera oleae, is the single most important pest for the majority of olive plantations. Oxitec's self-limiting olive fly technology (OX3097D-Bol) offers an alternative management approach to this insect pest. Because of previously reported asynchrony in the mating time of wild and laboratory strains, we have characterized the olive fly circadian clock applying molecular, evolutionary, anatomical and behavioural approaches. Here we demonstrate that the olive fly clock relies on a Drosophila melanogaster-like organization and that OX3097D-Bol carries a functional clock similar to wild-type strains, confirming its suitability for operational use.


Assuntos
Relógios Circadianos/genética , Redes Reguladoras de Genes , Tephritidae/genética , Tephritidae/fisiologia , Animais , Drosophila melanogaster/genética , Drosophila melanogaster/fisiologia , Olea/parasitologia
15.
Curr Biol ; 27(6): 833-839, 2017 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-28262491

RESUMO

The genus Drosophila contains over 2,000 species that, stemming from a common ancestor in the Old World Tropics, populate today very different environments [1, 2] (reviewed in [3]). We found significant differences in the activity pattern of Drosophila species belonging to the holarctic virilis group, i.e., D. ezoana and D. littoralis, collected in Northern Europe, compared to that of the cosmopolitan D. melanogaster, collected close to the equator. These behavioral differences might have been of adaptive significance for colonizing high-latitude habitats and hence adjust to long photoperiods. Most interestingly, the flies' locomotor activity correlates with the neurochemistry of their circadian clock network, which differs between low and high latitude for the expression pattern of the blue light photopigment cryptochrome (CRY) and the neuropeptide Pigment-dispersing factor (PDF) [4-6]. In D. melanogaster, CRY and PDF are known to modulate the timing of activity and to maintain robust rhythmicity under constant conditions [7-11]. We could partly simulate the rhythmic behavior of the high-latitude virilis group species by mimicking their CRY/PDF expression patterns in a laboratory strain of D. melanogaster. We therefore suggest that these alterations in the CRY/PDF clock neurochemistry might have allowed the virilis group species to colonize high-latitude environments.


Assuntos
Relógios Circadianos/genética , Drosophila/fisiologia , Locomoção , Rede Nervosa/fisiologia , Fotoperíodo , Animais , Drosophila/genética , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Finlândia , Masculino , Especificidade da Espécie , Tanzânia
16.
J Neurosci ; 36(35): 9084-96, 2016 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-27581451

RESUMO

UNLABELLED: A sensitivity of the circadian clock to light/dark cycles ensures that biological rhythms maintain optimal phase relationships with the external day. In animals, the circadian clock neuron network (CCNN) driving sleep/activity rhythms receives light input from multiple photoreceptors, but how these photoreceptors modulate CCNN components is not well understood. Here we show that the Hofbauer-Buchner eyelets differentially modulate two classes of ventral lateral neurons (LNvs) within the Drosophila CCNN. The eyelets antagonize Cryptochrome (CRY)- and compound-eye-based photoreception in the large LNvs while synergizing CRY-mediated photoreception in the small LNvs. Furthermore, we show that the large LNvs interact with subsets of "evening cells" to adjust the timing of the evening peak of activity in a day length-dependent manner. Our work identifies a peptidergic connection between the large LNvs and a group of evening cells that is critical for the seasonal adjustment of circadian rhythms. SIGNIFICANCE STATEMENT: In animals, circadian clocks have evolved to orchestrate the timing of behavior and metabolism. Consistent timing requires the entrainment these clocks to the solar day, a process that is critical for an organism's health. Light cycles are the most important external cue for the entrainment of circadian clocks, and the circadian system uses multiple photoreceptors to link timekeeping to the light/dark cycle. How light information from these photorecptors is integrated into the circadian clock neuron network to support entrainment is not understood. Our results establish that input from the HB eyelets differentially impacts the physiology of neuronal subgroups. This input pathway, together with input from the compound eyes, precisely times the activity of flies under long summer days. Our results provide a mechanistic model of light transduction and integration into the circadian system, identifying new and unexpected network motifs within the circadian clock neuron network.


Assuntos
Ritmo Circadiano/fisiologia , Atividade Motora/fisiologia , Neurônios/fisiologia , Fotoperíodo , Células Fotorreceptoras de Invertebrados/fisiologia , Sono/fisiologia , Animais , Animais Geneticamente Modificados , Antígenos CD4/genética , Antígenos CD4/metabolismo , Cálcio/metabolismo , Ritmo Circadiano/genética , Criptocromos , AMP Cíclico/metabolismo , Drosophila , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Histamina/farmacologia , Luz , Atividade Motora/genética , Rede Nervosa/fisiologia , Neuropeptídeos/genética , Neuropeptídeos/metabolismo , Interferência de RNA/fisiologia , Receptores Purinérgicos P2X2/genética , Receptores Purinérgicos P2X2/metabolismo , Rodopsina/genética , Rodopsina/metabolismo , Sono/genética , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Vias Visuais/fisiologia
17.
Nat Commun ; 7: 10165, 2016 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-26836814

RESUMO

The bed bug, Cimex lectularius, has re-established itself as a ubiquitous human ectoparasite throughout much of the world during the past two decades. This global resurgence is likely linked to increased international travel and commerce in addition to widespread insecticide resistance. Analyses of the C. lectularius sequenced genome (650 Mb) and 14,220 predicted protein-coding genes provide a comprehensive representation of genes that are linked to traumatic insemination, a reduced chemosensory repertoire of genes related to obligate hematophagy, host-symbiont interactions, and several mechanisms of insecticide resistance. In addition, we document the presence of multiple putative lateral gene transfer events. Genome sequencing and annotation establish a solid foundation for future research on mechanisms of insecticide resistance, human-bed bug and symbiont-bed bug associations, and unique features of bed bug biology that contribute to the unprecedented success of C. lectularius as a human ectoparasite.


Assuntos
Percevejos-de-Cama/genética , Ectoparasitoses , Comportamento Alimentar , Transferência Genética Horizontal/genética , Interações Hospedeiro-Parasita/genética , Resistência a Inseticidas/genética , Inseticidas , Animais , Genoma , Humanos , Análise de Sequência de DNA
18.
Proc Biol Sci ; 282(1815)2015 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-26378222

RESUMO

Circadian clocks are thought to be essential for timing the daily activity of animals, and consequently increase fitness. This view was recently challenged for clock-less fruit flies and mice that exhibited astonishingly normal activity rhythms under outdoor conditions. Compensatory mechanisms appear to enable even clock mutants to live a normal life in nature. Here, we show that gradual daily increases/decreases of light in the laboratory suffice to provoke normally timed sharp morning (M) and evening (E) activity peaks in clock-less flies. We also show that the compound eyes, but not Cryptochrome (CRY), mediate the precise timing of M and E peaks under natural-like conditions, as CRY-less flies do and eyeless flies do not show these sharp peaks independently of a functional clock. Nevertheless, the circadian clock appears critical for anticipating dusk, as well as for inhibiting sharp activity peaks during midnight. Clock-less flies only increase E activity after dusk and not before the beginning of dusk, and respond strongly to twilight exposure in the middle of the night. Furthermore, the circadian clock responds to natural-like light cycles, by slightly broadening Timeless (TIM) abundance in the clock neurons, and this effect is mediated by CRY.


Assuntos
Criptocromos/genética , Drosophila melanogaster/fisiologia , Luz , Animais , Relógios Circadianos , Olho Composto de Artrópodes/fisiologia , Criptocromos/fisiologia , Drosophila melanogaster/genética , Locomoção , Masculino , Fotoperíodo
19.
J Biol Rhythms ; 30(2): 117-28, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25838418

RESUMO

Light is the most important zeitgeber for the synchronization of the Drosophila melanogaster circadian clock. In nature, there is twilight, and the nights are rarely completely dark, a fact that is usually disregarded in lab experiments. Recent studies showed contrary effects of simulated twilight and moonlight on fly locomotor activity, with twilight shifting morning and evening activity into the day and moonlight shifting it into the night. A currently unanswered question is, what may happen to locomotor activity when flies are exposed to more natural conditions in which both moonlight and twilight are simulated? Our data demonstrate that flies are able to integrate twilight and moonlight. However, twilight seems to dominate over moonlight as both, morning and evening activity peaks, take place at dawn or at dusk, respectively, and not during the night. Furthermore, nocturnal activity decreases in the presence of twilight. The compound eyes are essential for this behavior, and by investigating different photoreceptor mutants, we unraveled the importance of photoreceptor cells 7 and 8 for wild-type phases of the activity peaks. To adjust nocturnal activity levels to a wild-type manner, all photoreceptor cells work together in a complex way, with rhodopsin 6 having a prominent role.


Assuntos
Ritmo Circadiano/fisiologia , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/fisiologia , Atividade Motora/fisiologia , Fotoperíodo , Células Fotorreceptoras de Invertebrados/fisiologia , Rodopsina/metabolismo , Animais , Relógios Biológicos , Escuridão , Luz , Mutação
20.
J Biol Rhythms ; 28(1): 3-14, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23382587

RESUMO

The circadian clock modulates the adaptive daily patterns of physiology and behavior and adjusts these rhythms to seasonal changes. Recent studies of seasonal locomotor activity patterns of wild-type and clock mutant fruit flies in quasi-natural conditions have revealed that these behavioral patterns differ considerably from those observed under standard laboratory conditions. To unravel the molecular features accompanying seasonal adaptation of the clock, we investigated Drosophila's neuronal expression of the canonical clock proteins PERIOD (PER) and TIMELESS (TIM) in nature. We find that the profile of PER dramatically changes in different seasons, whereas that of TIM remains more constant. Unexpectedly, we find that PER and TIM oscillations are decoupled in summer conditions. Moreover, irrespective of season, PER and TIM always peak earlier in the dorsal neurons than in the lateral neurons, suggesting a more rapid molecular oscillation in these cells. We successfully reproduced most of our results under simulated natural conditions in the laboratory and show that although photoperiod is the most important zeitgeber for the molecular clock, the flies' activity pattern is more strongly affected by temperature. Our results are among the first to systematically compare laboratory and natural studies of Drosophila rhythms.


Assuntos
Relógios Circadianos/fisiologia , Ritmo Circadiano/fisiologia , Proteínas de Drosophila/fisiologia , Drosophila/fisiologia , Neurônios/fisiologia , Proteínas Circadianas Period/fisiologia , Animais , Drosophila/metabolismo , Proteínas de Drosophila/metabolismo , Atividade Motora/fisiologia , Neurônios/metabolismo , Proteínas Nucleares/metabolismo , Proteínas Circadianas Period/metabolismo , Fotoperíodo , Estações do Ano
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