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Batra, T.; Malik, I.; Prabhat, A.; Bhardwaj, S.K.; Kumar, V. |
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Title |
Sleep in unnatural times: illuminated night negatively affects sleep and associated hypothalamic gene expressions in diurnal zebra finches |
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Journal Article |
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Year |
2020 |
Publication |
Proceedings. Biological Sciences |
Abbreviated Journal |
Proc Biol Sci |
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Volume |
287 |
Issue |
1928 |
Pages  |
20192952 |
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Keywords |
Animals; bird; dim light at night; gene expression; hypothalamus; sleep; zebra finch |
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Abstract |
We investigated the effects of exposure at ecologically relevant levels of dim light at night (dLAN) on sleep and the 24 h hypothalamic expression pattern of genes involved in the circadian timing (per2, bmal1, reverb-beta, cry1, ror-alpha, clock) and sleep regulatory pathways (cytokines: tlr4, tnf-alpha, il-1beta, nos; Ca(2+)-dependent pathway: camk2, sik3, nr3a; cholinergic receptor, achm3) in diurnal female zebra finches. Birds were exposed to 12 h light (150 lux) coupled with 12 h of absolute darkness or of 5 lux dim light for three weeks. dLAN fragmented the nocturnal sleep in reduced bouts, and caused sleep loss as evidenced by reduced plasma oxalate levels. Under dLAN, the 24 h rhythm of per2, but not bmal1 or reverb-beta, showed a reduced amplitude and altered peak expression time; however, clock, ror-alpha and cry1 expressions showed an abolition of the 24 h rhythm. Decreased tlr4, il-1beta and nos, and the lack of diurnal difference in achm3 messenger RNA levels suggested an attenuated inhibition of the arousal system (hence, awake state promotion) under dLAN. Similarly, changes in camk2, sik3 and nr3a expressions suggested dLAN-effects on Ca(2+)-dependent sleep-inducing pathways. These results demonstrate dLAN-induced negative effects on sleep and associated hypothalamic molecular pathways, and provide insights into health risks of illuminated night exposures to diurnal animals. |
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Department of Zoology, University of Delhi, Delhi 110 007, India |
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0962-8452 |
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PMID:32517617 |
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GFZ @ kyba @ |
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2995 |
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Author |
Elgert, C.; Hopkins, J.; Kaitala, A.; Candolin, U. |
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Title |
Reproduction under light pollution: maladaptive response to spatial variation in artificial light in a glow-worm |
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Journal Article |
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Year |
2020 |
Publication |
Proceedings of the Royal Society B: Biological Sciences |
Abbreviated Journal |
Proc. R. Soc. B. |
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Volume |
287 |
Issue |
1931 |
Pages |
20200806 |
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Keywords |
Animals; glow-worms; Lampyris noctiluca; insects; maladaptive response; reproduction |
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Abstract |
The amount of artificial light at night is growing worldwide, impacting the behaviour of nocturnal organisms. Yet, we know little about the consequences of these behavioural responses for individual fitness and population viability. We investigated if females of the common glow-worm Lampyris noctiluca—which glow in the night to attract males—mitigate negative effects of artificial light on mate attraction by adjusting the timing and location of glowing to spatial variation in light conditions. We found females do not move away from light when exposed to a gradient of artificial light, but delay or even refrain from glowing. Further, we demonstrate that this response is maladaptive, as our field study showed that staying still when exposed to artificial light from a simulated streetlight decreases mate attraction success, while moving only a short distance from the light source can markedly improve mate attraction. These results indicate that glow-worms are unable to respond to spatial variation in artificial light, which may be a factor in their global decline. Consequently, our results support the hypothesis that animals often lack adaptive behavioural responses to anthropogenic environmental changes and underlines the importance of considering behavioural responses when investigating the effects of human activities on wildlife. |
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Organismal and Evolutionary Biology, University of Helsinki, PO Box 65, 00014 Helsinki, Finland; christina.elgert(at)helsinki.fi |
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Royal Society |
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English |
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0962-8452 |
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IDA @ john @ |
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3049 |
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Richardson, M.E.S.; Parkins, S.; Kaneza, I.; Dauphin, A.-C. |
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Title |
Jet Lag Recovery and Memory Functions Are Correlated with Direct Light Effects on Locomotion |
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Journal Article |
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Year |
2020 |
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Journal of Biological Rhythms |
Abbreviated Journal |
J Biol Rhythms |
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in press |
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748730420947589 |
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Animals; activity; behavior; entrainment; jet lag; light therapy; masking; memory |
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Jet lag is a circadian disruption that affects millions of people, resulting, among other things, in extreme sleepiness and memory loss. The hazardous implications of such effects are evident in situations in which focus and attention are required. Remarkably, there is a limited understanding of how jet lag recovery and associated memory loss vary year round under different photoperiods. Here we show, using different cycles representing winter, summer, and equinox in male mice, that jet lag recovery and memory vary significantly with photoperiod changes. We uncover a positive correlation of acute light effects on circadian-driven locomotion (known as negative masking) with photoentrainment speed and memory enhancement during jet lag. Specifically, we show that enhancing or reducing negative masking is correlated with better or worse memory performance, respectively. This study indicates that in addition to timed-light exposure for phase shifting, the negative masking response could also be biologically relevant when designing effective treatments of jet lag. |
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Department of Biological Sciences, Oakwood University, Huntsville, Alabama |
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0748-7304 |
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PMID:32877295 |
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no |
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GFZ @ kyba @ |
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3130 |
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Author |
Hozer, C.; Pifferi, F. |
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Title |
Physiological and cognitive consequences of a daily 26 h photoperiod in a primate: exploring the underlying mechanisms of the circadian resonance theory |
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Journal Article |
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Year |
2020 |
Publication |
Proceedings. Biological Sciences |
Abbreviated Journal |
Proc Biol Sci |
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Volume |
287 |
Issue |
1931 |
Pages |
20201079 |
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Keywords |
Animals; Body Temperature; Cheirogaleidae/*physiology; Circadian Clocks; *Circadian Rhythm; Cognition; Male; Motor Activity; Photoperiod; Vibration; *circadian clock resonance; *cognition; *physiological costs; *synchronization |
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The biological clock expresses circadian rhythms, whose endogenous period (tau) is close to 24 h. Daily resetting of the circadian clock to the 24 h natural photoperiod might induce marginal costs that would accumulate over time and forward affect fitness. It was proposed as the circadian resonance theory. For the first time, we aimed to evaluate these physiological and cognitive costs that would partially explain the mechanisms of the circadian resonance hypothesis. We evaluated the potential costs of imposing a 26 h photoperiodic regimen compared to the classical 24 h entrainment measuring several physiological and cognitive parameters (body temperature, energetic expenditure, oxidative stress, cognitive performances) in males of a non-human primate (Microcebus murinus), a nocturnal species whose endogenous period is about 23.5 h. We found significant higher resting body temperature and energy expenditure and lower cognitive performances when the photoperiodic cycle length was 26 h. Together these results suggest that a great deviation of external cycles from tau leads to daily greater energetic expenditure, and lower cognitive capacities. To our knowledge, this study is the first to highlight potential mechanisms of circadian resonance theory. |
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UMR CNRS MNHN 7179 MECADEV, 1 Avenue du Petit Chateau 91800 Brunoy, France |
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0962-8452 |
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PMID:32693726; PMCID:PMC7423648 |
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GFZ @ kyba @ |
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3243 |
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Author |
Shima, J.S.; Osenberg, C.W.; Noonburg, E.G.; Alonzo, S.H.; Swearer, S.E. |
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Title |
Lunar rhythms in growth of larval fish |
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Journal Article |
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Year |
2021 |
Publication |
Proceedings. Biological Sciences |
Abbreviated Journal |
Proc Biol Sci |
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Volume |
288 |
Issue |
1942 |
Pages |
20202609 |
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Keywords |
Moonlight; Animals; developmental history; larval growth; lunar periodicity; reef fish; trophic connectivity |
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Growth and survival of larval fishes is highly variable and unpredictable. Our limited understanding of this variation constrains our ability to forecast population dynamics and effectively manage fisheries. Here we show that daily growth rates of a coral reef fish (the sixbar wrasse, Thalassoma hardwicke) are strongly lunar-periodic and predicted by the timing of nocturnal brightness: growth was maximized when the first half of the night was dark and the second half of the night was bright. Cloud cover that obscured moonlight facilitated a 'natural experiment', and confirmed the effect of moonlight on growth. We suggest that lunar-periodic growth may be attributable to light-mediated suppression of diel vertical migrations of predators and prey. Accounting for such effects will improve our capacity to predict the future dynamics of marine populations, especially in response to climate-driven changes in nocturnal cloud cover and intensification of artificial light, which could lead to population declines by reducing larval survival and growth. |
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School of BioSciences, University of Melbourne, Parkville, Victoria, Australia |
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0962-8452 |
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PMID:33434460 |
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GFZ @ kyba @ |
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3249 |
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