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Author Gerrish, G.A.; Morin, J.G.; Rivers, T.J.; Patrawala, Z.
Title Darkness as an ecological resource: the role of light in partitioning the nocturnal niche Type Journal Article
Year 2009 Publication Oecologia Abbreviated Journal Oecologia
Volume 160 Issue 3 Pages 525-536
Keywords Age Factors; Animals; Belize; Crustacea/*physiology; *Darkness; *Ecosystem; Feeding Behavior/physiology; Linear Models; Motor Activity/*physiology; Photoperiod; Sexual Behavior, Animal/physiology; Water Movements
Abstract Nocturnal behaviors that vary as a function of light intensity, either from the setting sun or the moon, are typically labeled as circadian or circalunar. Both of these terms refer to endogenous time-dependent behaviors. In contrast, the nightly reproductive and feeding behaviors of Vargula annecohenae, a bioluminescent ostracod (Arthropoda: Crustacea) fluctuate in response to light intensity, an exogenous factor that is not strictly time-dependent. We measured adult and juvenile activity of V. annecohenae throughout lunar cycles in January/February and June 2003. Overnight and nightly measurements of foraging and reproductive behavior of adult V. annecohenae indicated that activity was greatest when a critical “dark threshold” was reached and that the dark threshold for adult V. annecohenae is met when less than a third of the moon is visible or at the intensity of light 2-3 min before the start of nautical twilight when no moon is illuminated. Juvenile V. annecohenae were also nocturnally active but demonstrated little or no response to lunar illumination, remaining active even during brightly moonlit periods. In addition to light level, water velocity also influenced the behaviors of V. annecohenae, with fewer juveniles and adults actively foraging on nights when water velocity was high (>25 cm/s). Our data demonstrate that the strongest environmental factor influencing adult feeding and reproductive behaviors of V. annecohenae is the availability of time when illumination is below the critical dark threshold. This dependence on darkness for successful growth and reproduction allows us to classify darkness as a resource, in the same way that the term has been applied to time, space and temperature.
Address (up) Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14850, USA. ggerrish@nd.edu
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0029-8549 ISBN Medium
Area Expedition Conference
Notes PMID:19330516 Approved no
Call Number IDA @ john @ Serial 16
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Author Fonken, L.K.; Aubrecht, T.G.; Melendez-Fernandez, O.H.; Weil, Z.M.; Nelson, R.J.
Title Dim light at night disrupts molecular circadian rhythms and increases body weight Type Journal Article
Year 2013 Publication Journal of Biological Rhythms Abbreviated Journal J Biol Rhythms
Volume 28 Issue 4 Pages 262-271
Keywords Animals; Blood Glucose/metabolism; Body Weight/*physiology; CLOCK Proteins/biosynthesis/genetics; Circadian Rhythm/*physiology; Corticosterone/metabolism; Feeding Behavior/physiology; Immunohistochemistry; Light; *Lighting; Male; Mice; Motor Activity; Polymerase Chain Reaction; Suprachiasmatic Nucleus/metabolism/physiology; clock genes; feeding rhythm; light pollution; obesity
Abstract With the exception of high latitudes, life has evolved under bright days and dark nights. Most organisms have developed endogenously driven circadian rhythms that are synchronized to this daily light/dark cycle. In recent years, humans have shifted away from the naturally occurring solar light cycle in favor of artificial and sometimes irregular light schedules produced by electric lighting. Exposure to unnatural light cycles is increasingly associated with obesity and metabolic syndrome; however, the means by which environmental lighting alters metabolism are poorly understood. Thus, we exposed mice to dim light at night and investigated changes in the circadian system and metabolism. Here we report that exposure to ecologically relevant levels of dim (5 lux) light at night altered core circadian clock rhythms in the hypothalamus at both the gene and protein level. Circadian rhythms in clock expression persisted during light at night; however, the amplitude of Per1 and Per2 rhythms was attenuated in the hypothalamus. Circadian oscillations were also altered in peripheral tissues critical for metabolic regulation. Exposure to dimly illuminated, as compared to dark, nights decreased the rhythmic expression in all but one of the core circadian clock genes assessed in the liver. Additionally, mice exposed to dim light at night attenuated Rev-Erb expression in the liver and adipose tissue. Changes in the circadian clock were associated with temporal alterations in feeding behavior and increased weight gain. These results are significant because they provide evidence that mild changes in environmental lighting can alter circadian and metabolic function. Detailed analysis of temporal changes induced by nighttime light exposure may provide insight into the onset and progression of obesity and metabolic syndrome, as well as other disorders involving sleep and circadian rhythm disruption.
Address (up) Department of Neuroscience and Institute for Behavioral Medicine Research, Wexner Medical Center, The Ohio State University, Columbus, OH 43210, USA. fonken.1@osu.edu
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0748-7304 ISBN Medium
Area Expedition Conference
Notes PMID:23929553; PMCID:PMC4033305 Approved no
Call Number IDA @ john @ Serial 28
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Author Bedrosian, T.A.; Vaughn, C.A.; Galan, A.; Daye, G.; Weil, Z.M.; Nelson, R.J.
Title Nocturnal light exposure impairs affective responses in a wavelength-dependent manner Type Journal Article
Year 2013 Publication The Journal of Neuroscience : the Official Journal of the Society for Neuroscience Abbreviated Journal J Neurosci
Volume 33 Issue 32 Pages 13081-13087
Keywords Analysis of Variance; Animals; Circadian Rhythm/*physiology; Cricetinae; Dose-Response Relationship, Radiation; Female; Food Deprivation/physiology; Food Preferences/physiology/radiation effects; Fourier Analysis; Gene Expression Regulation/radiation effects; Hippocampus/pathology/radiation effects; Immobility Response, Tonic/radiation effects; Light/*adverse effects; Mood Disorders/*etiology/pathology; Motor Activity/physiology/radiation effects; Phodopus; Proto-Oncogene Proteins c-fos/metabolism; Social Behavior; Suprachiasmatic Nucleus/metabolism; Time Factors
Abstract Life on earth is entrained to a 24 h solar cycle that synchronizes circadian rhythms in physiology and behavior; light is the most potent entraining cue. In mammals, light is detected by (1) rods and cones, which mediate visual function, and (2) intrinsically photosensitive retinal ganglion cells (ipRGCs), which primarily project to the suprachiasmatic nucleus (SCN) in the hypothalamus to regulate circadian rhythms. Recent evidence, however, demonstrates that ipRGCs also project to limbic brain regions, suggesting that, through this pathway, light may have a role in cognition and mood. Therefore, it follows that unnatural exposure to light may have negative consequences for mood or behavior. Modern environmental lighting conditions have led to excessive exposure to light at night (LAN), and particularly to blue wavelength lights. We hypothesized that nocturnal light exposure (i.e., dim LAN) would induce depressive responses and alter neuronal structure in hamsters (Phodopus sungorus). If this effect is mediated by ipRGCs, which have reduced sensitivity to red wavelength light, then we predicted that red LAN would have limited effects on brain and behavior compared with shorter wavelengths. Additionally, red LAN would not induce c-Fos activation in the SCN. Our results demonstrate that exposure to LAN influences behavior and neuronal plasticity and that this effect is likely mediated by ipRGCs. Modern sources of LAN that contain blue wavelengths may be particularly disruptive to the circadian system, potentially contributing to altered mood regulation.
Address (up) Department of Neuroscience, Ohio State University Wexner Medical Center, Columbus, Ohio 43210, USA. Bedrosian.2@osu.edu
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0270-6474 ISBN Medium
Area Expedition Conference
Notes PMID:23926261 Approved no
Call Number IDA @ john @ Serial 27
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Author Fonken, L.K.; Workman, J.L.; Walton, J.C.; Weil, Z.M.; Morris, J.S.; Haim, A.; Nelson, R.J.
Title Light at night increases body mass by shifting the time of food intake Type Journal Article
Year 2010 Publication Proceedings of the National Academy of Sciences of the United States of America Abbreviated Journal Proc Natl Acad Sci U S A
Volume 107 Issue 43 Pages 18664-18669
Keywords Animals; Body Mass Index; *Circadian Rhythm; Disease Models, Animal; Eating/*physiology/psychology/*radiation effects; Energy Intake; Feeding Behavior/physiology/psychology/radiation effects; Glucose Tolerance Test; Humans; Male; Metabolic Syndrome X/etiology; Mice; Motor Activity; Obesity/*etiology/pathology/physiopathology/psychology; *Photoperiod
Abstract The global increase in the prevalence of obesity and metabolic disorders coincides with the increase of exposure to light at night (LAN) and shift work. Circadian regulation of energy homeostasis is controlled by an endogenous biological clock that is synchronized by light information. To promote optimal adaptive functioning, the circadian clock prepares individuals for predictable events such as food availability and sleep, and disruption of clock function causes circadian and metabolic disturbances. To determine whether a causal relationship exists between nighttime light exposure and obesity, we examined the effects of LAN on body mass in male mice. Mice housed in either bright (LL) or dim (DM) LAN have significantly increased body mass and reduced glucose tolerance compared with mice in a standard (LD) light/dark cycle, despite equivalent levels of caloric intake and total daily activity output. Furthermore, the timing of food consumption by DM and LL mice differs from that in LD mice. Nocturnal rodents typically eat substantially more food at night; however, DM mice consume 55.5% of their food during the light phase, as compared with 36.5% in LD mice. Restricting food consumption to the active phase in DM mice prevents body mass gain. These results suggest that low levels of light at night disrupt the timing of food intake and other metabolic signals, leading to excess weight gain. These data are relevant to the coincidence between increasing use of light at night and obesity in humans.
Address (up) Department of Neuroscience, Ohio State University, Columbus, OH 43210, USA. fonken.1@osu.edu
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0027-8424 ISBN Medium
Area Expedition Conference
Notes PMID:20937863; PMCID:PMC2972983 Approved no
Call Number IDA @ john @ Serial 169
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Author Bedrosian, T.A.; Fonken, L.K.; Walton, J.C.; Nelson, R.J.
Title Chronic exposure to dim light at night suppresses immune responses in Siberian hamsters Type Journal Article
Year 2011 Publication Biology Letters Abbreviated Journal Biol Lett
Volume 7 Issue 3 Pages 468-471
Keywords Animals; Blood Bactericidal Activity/immunology; Circadian Rhythm; Cricetinae; Fever/immunology; Hypersensitivity, Delayed/immunology; *Immunity; Light/*adverse effects; Lipopolysaccharides; Locomotion; Phodopus/*immunology
Abstract Species have been adapted to specific niches optimizing survival and reproduction; however, urbanization by humans has dramatically altered natural habitats. Artificial light at night (LAN), termed 'light pollution', is an often overlooked, yet increasing disruptor of habitats, which perturbs physiological processes that rely on precise light information. For example, LAN alters the timing of reproduction and activity in some species, which decreases the odds of successful breeding and increases the threat of predation for these individuals, leading to reduced fitness. LAN also suppresses immune function, an important proxy for survival. To investigate the impact of LAN in a species naive to light pollution in its native habitat, immune function was examined in Siberian hamsters derived from wild-caught stock. After four weeks exposure to dim LAN, immune responses to three different challenges were assessed: (i) delayed-type hypersensitivity (DTH), (ii) lipopolysaccharide-induced fever, and (iii) bactericide activity of blood. LAN suppressed DTH response and reduced bactericide activity of blood after lipopolysaccharide treatment, in addition to altering daily patterns of locomotor activity, suggesting that human encroachment on habitats via night-time lighting may inadvertently compromise immune function and ultimately fitness.
Address (up) Department of Neuroscience, The Ohio State University Medical Center, Columbus, OH 43210, USA. tracy.bedrosian@osumc.edu
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1744-9561 ISBN Medium
Area Expedition Conference
Notes PMID:21270021; PMCID:PMC3097873 Approved no
Call Number IDA @ john @ Serial 90
Permanent link to this record