Document Detail


Melatonin rhythms in the Australian freshwater crocodile (Crocodylus johnstoni): a reptile lacking a pineal complex?
MedLine Citation:
PMID:  19585125     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The vertebrate pineal gland is the primary source of melatonin, the rhythmic secretion of which is influenced by environmental light and temperature, thereby providing animals with information about seasonally changing photoperiod and thermoperiod. Although pineal glands are present in the majority of vertebrate species, a discrete organ is reported to be absent in the Crocodilia. However, if the melatonin rhythm is crucial to the survival of the organism, it would be expected that the rhythm would be present in crocodiles. In the present study, we measured blood plasma melatonin over a 30-h period in aestivating Australian freshwater crocodiles (Crocodylus johnstoni) in their natural habitat at the end of the dry season (November) and found no discernible melatonin rhythm. However, another group of captive-reared C. johnstoni, maintained under natural light and temperature cycles and sampled in the early dry season (June) showed a clear melatonin rhythm. These results suggest that there is either an extrapineal source of melatonin in this crocodile species or that there is melatonin producing tissue elsewhere which heretofore has not been discovered. Further studies are needed to determine why the melatonin rhythm is intermittently expressed and whether this may be related to seasonal changes in the expression of the rhythm linked to tropical environments.
Authors:
Bruce T Firth; Keith A Christian; Ingrid Belan; David J Kennaway
Related Documents :
18534755 - Effects of short wavelength control in polychromatic light sources on nocturnal melaton...
24634985 - Detection of gunshot residue on dark-colored clothing prior to chemical analysis.
3045925 - How does melatonin control seasonal reproductive cycles?
12622835 - Photic and circadian regulation of retinal melatonin in mammals.
24220775 - Phototropism of maize coleoptiles influences of light gradients.
6806815 - Light-dependent effects of a hydrolysis-resistant analog of gtp on rod photoresponses i...
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-07-08
Journal Detail:
Title:  Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology     Volume:  180     ISSN:  1432-136X     ISO Abbreviation:  J. Comp. Physiol. B, Biochem. Syst. Environ. Physiol.     Publication Date:  2010 Jan 
Date Detail:
Created Date:  2009-12-30     Completed Date:  2010-03-15     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8413200     Medline TA:  J Comp Physiol B     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  67-72     Citation Subset:  IM    
Affiliation:
Discipline of Anatomical Sciences, Faculty of Health Sciences, School of Medical Sciences, University of Adelaide, Adelaide, SA, 5005, Australia. bruce.firth@adelaide.edu.au
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Descriptor/Qualifier:
Adaptation, Biological
Alligators and Crocodiles / blood,  physiology*
Animals
Animals, Wild / blood,  physiology
Circadian Rhythm*
Fresh Water
Melatonin / blood*,  metabolism
Northern Territory
Photoperiod
Seasons
Temperature
Chemical
Reg. No./Substance:
73-31-4/Melatonin

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


Previous Document:  Unclear deterioration of vison after renal transplant.
Next Document:  Infantile encephalopathy due to vitamin deficiency in industrial countries.