| Records |
| Author |
Prabhat, A.; Malik, I.; Jha, N.A.; Bhardwaj, S.K.; Kumar, V. |
| Title |
Developmental effects of constant light on circadian behaviour and gene expressions in zebra finches: Insights into mechanisms of metabolic adaptation to aperiodic environment in diurnal animals |
Type |
Journal Article |
| Year |
2020 |
Publication |
Journal of Photochemistry and Photobiology B: Biology |
Abbreviated Journal |
Journal of Photochemistry and Photobiology B: Biology |
| Volume |
in press |
Issue |
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Pages |
111995 |
| Keywords |
Animals |
| Abstract |
A most crucial feature of biological adaptation is the maintenance of a close temporal relationship of behaviour and physiology with prevailing 24-h light-dark environment, which is rapidly changing with increasing nighttime illumination. This study investigated developmental effects of the loss of night on circadian behaviour, metabolism and gene expressions in diurnal zebra finches born and raised under LL, with controls on 12 L:12D. Birds under LD were entrained, and showed normal body mass and a significant 24-h rhythm in both activity-rest pattern and mRNA expression of candidate genes that we measured. But, under LL, birds gained weight and accumulated lipid in the liver. Intriguingly, at the end of the experiment, the majority (4/5th) of birds under LL were rhythmic in activity despite arrhythmic expression in the hypothalamus of c-Fos (neuronal activity), Rhodopsin and Mel1-a genes (light perception), and clock genes (Bmal1, Per2 and Rev-erb β). In peripheral tissues, LL induced variable clock gene expressions. Whereas 24-h mRNA rhythm was abolished for Bmal1 in both liver and gut, it persisted for Per2 and Rev-erb β in liver, and for Per2 in gut. Further, we found under LL, the loss of 24-h rhythm in hepatic expression of Fasn and Cd36/Fat (biosynthesis and its uptake), and gut expression of Sglt1, Glut5, Cd36 and Pept1 (nutrient absorption) genes. As compared to LD, baseline mRNA levels of Fasn and Cd36 genes were attenuated under LL. Among major transporter genes, Sglt1 (glucose) and Cd36 (fat) genes were arrhythmic, while Glut5 (glucose) and Pept1 (protein) genes were rhythmic but with phase differences under LL, compared to LD. These results demonstrate dissociation of circadian behaviour from clock gene rhythms, and provide molecular insights into possible mechanisms at different levels (behaviour and physiology) that diurnal animals might employ in order to adapt to an emerging overly illuminated-night urban environment. |
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1011-1344 |
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GFZ @ kyba @ |
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3085 |
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Dickerson, A.L.; Hall, M.L.; Jones, T.M. |
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The effect of variation in moonlight on nocturnal song of a diurnal bird species |
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Journal Article |
| Year |
2020 |
Publication |
Behavioral Ecology and Sociobiology |
Abbreviated Journal |
Behav Ecol Sociobiol |
| Volume |
74 |
Issue |
9 |
Pages |
in press |
| Keywords |
Animals; Moonlight |
| Abstract |
The lunar cycle is known to affect the behaviour of strictly nocturnal species, but for diurnal species that are periodically active during the night, this has been less investigated. Nocturnal bird song is relatively common in diurnal species, yet research on this behaviour accounts for little of the research on avian vocalisations. This is surprising given that diurnal species are adapted for bright environments and therefore may be particularly sensitive to change in the lunar cycles. We used automated bioacoustic recorders and automatic song detection software to measure nocturnal song rate in a diurnal bird where both sexes sing, the willie wagtail (Rhipidura leucophrys). We deployed recorders at eight locations across four naturally dark sites resulting in 457 h of nocturnal audio. We confirmed anecdotal evidence suggesting that willie wagtails are prolific nocturnal singers during the breeding season and demonstrate that while both male and females sing during the day, nocturnal song is largely sung by males. Moreover, we show that nocturnal song increased with lunar illumination, contrasting with previous research on other diurnal species that sing at night. Our data allow us to hypothesise possible functions for nocturnal song in this species, such as territory defence or mate attraction. |
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0340-5443 |
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GFZ @ kyba @ |
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3084 |
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Matsumoto, S.-I.; Shirahashi, K. |
| Title |
Novel perspectives on the influence of the lunar cycle on the timing of full-term human births |
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Journal Article |
| Year |
2020 |
Publication |
Chronobiology International |
Abbreviated Journal |
Chronobiol Int |
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in press |
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Moonlight; Human birth; full moon; lunar cycle; new moon |
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It is claimed by some that the number of births occurring at the time of the full moon is greater than other phases of the lunar cycle; however, many publications fail to substantiate the claim leading to the conclusion it is myth. We tested using a novel approach the null hypotheses: (i) human birth is not lunar cycle-dependent and (ii) the number of births occurring at or around the time of the full moon is not different from the number occurring at the time of the other phases of the lunar cycle. We reviewed the birth records from 1 January 1996 to 16 March 2007 of the obstetric department of our hospital, which was then located in a relatively undeveloped area of Fukutsu city in Fukuoka Prefecture of southern Japan. A total of 1507 births satisfied all inclusion criteria, among others, being full-term and following spontaneously initiated labor. When the birth data were analyzed as done by other investigators, i.e. total number of births per lunar day, lunar phase was not found to be influential. However, more detailed analyses on the subset of babies born specifically during the nighttime hours (N = 362) revealed the number of births varied in relation specifically to the changing amount of moonlight during the nighttime at different stages of the lunar cycle, with highest number of births at or around the time of the full moon. In contrast, analyses on the subset of babies born specifically during the daytime hours (N = 377) revealed the number of births varied in relation specifically to the changing amount moonlight during the daytime at different stages of the lunar cycle, with the highest number of births at or around the time of the new moon. The initiation and culmination of human birth are typically a nocturnal process. The findings of this investigation are consistent with the hypothesis natural nighttime parturition is influenced by lunar phase, particularly the full moon, and, thus, they are consistent with the belief the moon exerts an affect upon the timing of human birth. We speculate the long-hold belief of the association between birth and lunar phase may be based on historical observations that in the absence of artificial light at night nocturnal births occurred in elevated number when the full moon brightly illuminated the nighttime sky. |
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Department of Obstetrics and Gynecology, Munakata Suikokai General Hospital , Fukutsu, Fukuoka Prefecture, Japan |
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English |
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0742-0528 |
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| Notes |
PMID:32703035 |
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no |
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GFZ @ kyba @ |
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3083 |
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Foster, R.G.; Hughes, S.; Peirson, S.N. |
| Title |
Circadian Photoentrainment in Mice and Humans |
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Journal Article |
| Year |
2020 |
Publication |
Biology |
Abbreviated Journal |
Biology (Basel) |
| Volume |
9 |
Issue |
7 |
Pages |
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Review; Animals; Human Health; circadian; entrainment; human; melanopsin (OPN4); mouse; photoreceptor |
| Abstract |
Light around twilight provides the primary entrainment signal for circadian rhythms. Here we review the mechanisms and responses of the mouse and human circadian systems to light. Both utilize a network of photosensitive retinal ganglion cells (pRGCs) expressing the photopigment melanopsin (OPN4). In both species action spectra and functional expression of OPN4 in vitro show that melanopsin has a lambdamax close to 480 nm. Anatomical findings demonstrate that there are multiple pRGC sub-types, with some evidence in mice, but little in humans, regarding their roles in regulating physiology and behavior. Studies in mice, non-human primates and humans, show that rods and cones project to and can modulate the light responses of pRGCs. Such an integration of signals enables the rods to detect dim light, the cones to detect higher light intensities and the integration of intermittent light exposure, whilst melanopsin measures bright light over extended periods of time. Although photoreceptor mechanisms are similar, sensitivity thresholds differ markedly between mice and humans. Mice can entrain to light at approximately 1 lux for a few minutes, whilst humans require light at high irradiance (>100's lux) and of a long duration (>30 min). The basis for this difference remains unclear. As our retinal light exposure is highly dynamic, and because photoreceptor interactions are complex and difficult to model, attempts to develop evidence-based lighting to enhance human circadian entrainment are very challenging. A way forward will be to define human circadian responses to artificial and natural light in the “real world” where light intensity, duration, spectral quality, time of day, light history and age can each be assessed. |
| Address |
Sleep & Circadian Neuroscience Institute (SCNi), Nuffield Department of Clinical Neurosciences, Sir William Dunn School of Pathology, Oxford Molecular Pathology Institute, South Parks Road, University of Oxford, Oxford OX1 3RF, UK |
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English |
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2079-7737 |
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PMID:32708259; PMCID:PMC7408241 |
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no |
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GFZ @ kyba @ |
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3082 |
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Masis-Vargas, A.; Ritsema, W.I.G.R.; Mendoza, J.; Kalsbeek, A. |
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Metabolic Effects of Light at Night are Time- and Wavelength-Dependent in Rats |
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Journal Article |
| Year |
2020 |
Publication |
Obesity (Silver Spring, Md.) |
Abbreviated Journal |
Obesity (Silver Spring) |
| Volume |
28 Suppl 1 |
Issue |
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S114-S125 |
| Keywords |
Animals |
| Abstract |
OBJECTIVE: Intrinsically photosensitive retinal ganglion cells are most sensitive to short wavelengths and reach brain regions that modulate biological rhythms and energy metabolism. The increased exposure nowadays to artificial light at night (ALAN), especially short wavelengths, perturbs our synchronization with the 24-hour solar cycle. Here, the time- and wavelength dependence of the metabolic effects of ALAN are investigated. METHODS: Male Wistar rats were exposed to white, blue, or green light at different time points during the dark phase. Locomotor activity, energy expenditure, respiratory exchange ratio (RER), and food intake were recorded. Brains, livers, and blood were collected. RESULTS: All wavelengths decreased locomotor activity regardless of time of exposure, but changes in energy expenditure were dependent on the time of exposure. Blue and green light reduced RER at Zeitgeber time 16-18 without changing food intake. Blue light increased period 1 (Per1) gene expression in the liver, while green and white light increased Per2. Blue light decreased plasma glucose and phosphoenolpyruvate carboxykinase (Pepck) expression in the liver. All wavelengths increased c-Fos activity in the suprachiasmatic nucleus, but blue and green light decreased c-Fos activity in the paraventricular nucleus. CONCLUSIONS: ALAN affects locomotor activity, energy expenditure, RER, hypothalamic c-Fos expression, and expression of clock and metabolic genes in the liver depending on the time of day and wavelength. |
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Hypothalamic Integration Mechanisms, Netherlands Institute for Neuroscience (NIN), Amsterdam, The Netherlands |
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English |
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1930-7381 |
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| Notes |
PMID:32700824 |
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no |
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GFZ @ kyba @ |
Serial |
3081 |
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