Document Detail

Circadian organization and photoreception in an Australian dasyurid marsupial (Sminthopsis macroura).
MedLine Citation:
PMID:  2979665     Owner:  NLM     Status:  MEDLINE    
Much is known about the formal properties of circadian rhythm regulation and the physiological substrates underlying rhythmicity in nocturnal rodents, but relatively few studies have addressed circadian rhythm regulation in other mammalian taxonomic groups. In this study, some formal and functional aspects of circadian organization in a nocturnal dasyurid marsupial, the stripe-faced dunnart (Sminthopsis macroura), were analyzed. To determine phasic responses to discrete pulses of light, dunnarts were placed in constant darkness (DD) and were periodically administered pulses of bright light at different times of the animals' circadian day. Analysis of phase shifts in response to light indicated a phase response curve that was similar to responses observed in nocturnal rodents. To determine the possibility of extraretinal photoreception mediating photic entrainment, dunnarts were anesthetized and orbitally enucleated while maintained in a light-dark regimen (LD 14:10). All blinded dunnarts free-ran with periods (tau) that were similar to those observed in DD, indicating that entrainment is mediated through ocular photoreception. However, the data also indicated a decrease in activity in blind dunnarts during the last 3-5 hr of the dark phase, raising the possibility of some retention of photoreceptive capacities.
V M Cassone
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of biological rhythms     Volume:  2     ISSN:  0748-7304     ISO Abbreviation:  J. Biol. Rhythms     Publication Date:  1987  
Date Detail:
Created Date:  1992-02-19     Completed Date:  1992-02-19     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  8700115     Medline TA:  J Biol Rhythms     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  261-8     Citation Subset:  IM    
Department of Neurology, State University of New York, Stony Brook 11794.
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MeSH Terms
Circadian Rhythm / physiology*
Marsupialia / physiology*
Photoreceptor Cells / physiology*

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