Document Detail

The evolutionary physiology of photoperiodism in vertebrates.
MedLine Citation:
PMID:  22877678     Owner:  NLM     Status:  In-Data-Review    
The capacity to measure day length (photoperiod) is a trait subject to intense evolutionary pressure, and the circadian system has become an important part of the photoperiodic machinery. With the exception of mammals, vertebrates possess multiple sites of photosensitivity within the central nervous system through which light responses may be coordinated. Of these, deep brain photoreceptors play a special role in photoperiodism in nonmammalian vertebrates, independent of either retinal or pineal pathways. In mammals, the pineal hormone, melatonin has assumed a function orthologous to that of deep brain photoreceptors in other vertebrates. Contrasting with this dichotomy in photoperiodic input pathways, downstream signal processing to produce switch-like seasonal responses is largely conserved and appears to center on photoperiodic control of thyroid hormone bioavailability within the hypothalamus. Recent studies implicate the clock-controlled gene eyes absent 3 in linking the circadian clock to photoperiodic responses, dictating the seasonal level of expression of thyroid-stimulating hormone by a specialized population of photoperiodically sensitive cells in the pituitary stalk which in turn govern thyroid hormone metabolism in the basal hypothalamus. This ancestral control pathway appears to have originated prior to the divergence of the mammalian and avian vertebrate lineages.
David Hazlerigg
Related Documents :
18602178 - Stimulus frequency dependence of blood oxygenation level-dependent functional magnetic ...
1225438 - Stimulus generalization and anxiety in schizophrenic and normal subjects.
8865638 - Effects of stimulus duration on the amplitude difference limen for vibrotaction.
7899018 - Timing of anticipatory responses following an isometric contraction.
20362898 - Morphologic, functional, and occlusal characterization of mandibular lateral displaceme...
525308 - Contrast sensitivity in macular disease using a small-field and a large-field tv-system.
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Progress in brain research     Volume:  199     ISSN:  1875-7855     ISO Abbreviation:  Prog. Brain Res.     Publication Date:  2012  
Date Detail:
Created Date:  2012-08-10     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0376441     Medline TA:  Prog Brain Res     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  413-22     Citation Subset:  IM    
Copyright Information:
Copyright © 2012 Elsevier B.V. All rights reserved.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms

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

Previous Document:  Noisy and individual, but doable: Shift-work research in humans.
Next Document:  A kiss for daily and seasonal reproduction.