Abstract:
:Endogenous circadian rhythms are involved in various photoperiodic responses of birds. Investigations involving the mechanisms of photoperiodic time measurement in birds have been confined mainly to temperate zone species using males exclusively. Due to the paucity of experimental evidence on subtropical birds that have very wide distribution, the present study was performed using subtropical female house sparrows. Photoperiodic sparrows were subjected to various T cycles for 60 days in which a fixed 3-h photophase was combined with scotophase in cycles of 20-30 h duration. Simultaneously, two groups of birds were also exposed to short days (light:dark = 8L:16D) or long days (15L:9D) as controls. Significant ovarian growth was found only in cycles of 3L:17D, 3L:23D, 3L:25D, and 3L:27D as well as in 15L:9D, whereas no positive response was detected in 3L:19D, 3L:21D, and 8L:16D. Plasma levels of estradiol showed a close relation to ovarian growth. The results indicate that photoperiodic time measurement in house sparrows involves an endogenous circadian rhythm.
journal_name
J Biol Rhythmsjournal_title
Journal of biological rhythmsauthors
Ravikumar G,Senthilkumaran B,Tewary PD,Goel AKdoi
10.1177/074873049501000405subject
Has Abstractpub_date
1995-12-01 00:00:00pages
319-23issue
4eissn
0748-7304issn
1552-4531journal_volume
10pub_type
杂志文章abstract::Individuals of the shore crab Carcinus maenas were exposed to artificial cycles, applied in tidal antiphase, of pairs of the three major environmental variables that entrain circatidal rhythmicity in this species: salinity, temperature, and hydrostatic pressure. During entrainment, the observed locomotor activity patt...
journal_title:Journal of biological rhythms
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