| Photic induction of Fos in the suprachiasmatic nucleus of African mole-rats: responses to increasing irradiance. | |
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MedLine Citation:
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PMID: 20854133 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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African mole-rats (family Bathyergidae) are strictly subterranean rodent species that are rarely exposed to environmental light. Morphological and physiological adaptations to the underground environment include a severely reduced eye size and regressed visual system. Responses of the circadian system to light, however, appear to be intact, since mole-rats are able to entrain their circadian activity rhythms to the light-dark cycle and light induces Fos expression in the suprachiasmatic nucleus (SCN). Social organization varies from solitary species to highly elaborated eusocial structures, characterized by a distinct division of labor and in which one reproductive female regulates the behavior and reproductive physiology of other individuals in the colony. The authors studied light-induced Fos expression in the SCN to increasing light intensities in four mole-rat species, ranging from strictly solitary to highly social. In the solitary Cape mole-rat, light induces significant Fos expression in the SCN, and the number of Fos-immunopositive cells increases with increasing light intensity. In contrast, Fos induction in the SCN of social species was slightly greater than, but not statistically different from, the dark-control animals as is typical of most rodents. One species showed a trend for an increase in expression with increased light, whereas a second species showed no trend in expression. In the naked mole-rat, Fos expression appeared higher in the dark-controls than in the animals exposed to light, although the differences in Fos expression were not significant. These results suggest a gradient in the sensitivity of the circadian system to light in mole-rats, with a higher percentage of individuals that are unresponsive to light in correlation with the degree of sociality. In highly social species, such as the naked mole-rat that live in a relatively stable subterranean milieu in terms of food availability, temperature, constant darkness, and devoid of 24-h cyclic environmental cues, the temporal coordination of rest-wake activities may be dependent on social interactions and social status rather than on photic regulation of the circadian timing system. |
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Authors:
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Maria K Oosthuizen; Nigel C Bennett; Howard M Cooper |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Chronobiology international Volume: 27 ISSN: 1525-6073 ISO Abbreviation: Chronobiol. Int. Publication Date: 2010 Sep |
Date Detail:
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Created Date: 2010-09-21 Completed Date: 2011-01-06 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8501362 Medline TA: Chronobiol Int Country: England |
Other Details:
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Languages: eng Pagination: 1532-45 Citation Subset: IM |
Affiliation:
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Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa. moosthuizen@zoology.up.ac.za |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Circadian Clocks Circadian Rhythm / physiology Darkness Female Light* Mole Rats / metabolism* Photic Stimulation* Photoperiod Proto-Oncogene Proteins c-fos / metabolism* Rats Suprachiasmatic Nucleus / cytology, metabolism* |
| Chemical | |
Reg. No./Substance:
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0/Proto-Oncogene Proteins c-fos |
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