منابع مشابه
Photoperiodic regulation
Adult male wild rabbits were exposed to artificial daylengths of 8L:16D, 13L:1 1D or 20L:4D after being taken from the wild during September, when testicular size was minimal. In all groups the testes grew and those in 20L:4D grew more quickly than did those in 8L:16D or 13L:11D. Rabbits kept in the 3 daylength treatments for the whole study maintained enlarged testes after the initial growth p...
متن کاملPhotoperiodic Programming of the SCN and Its Role in Photoperiodic Output
Though the seasonal response of organisms to changing day lengths is a phenomenon that has been scientifically reported for nearly a century, significant questions remain about how photoperiod is encoded and effected neurobiologically. In mammals, early work identified the master circadian clock, the suprachiasmatic nuclei (SCN), as a tentative encoder of photoperiodic information. Here, we pro...
متن کاملPhotoperiodic regulation of puberty in seasonal species.
Puberty occurs seasonally in the majority of mammals native to temperate or arctic latitudes, and in species with sufficiently long life spans puberty can be considered to reoccur on an annual basis. The precise timing of puberty and the annual reoccurrence of fertility reflects an interaction of changes in ambient daylength (photoperiod) and endogenous long-term timing processes, which in some...
متن کاملRegulation of photoperiodic flowering by Arabidopsis photoreceptors.
Photoperiodism is a day-length-dependent seasonal change of physiological or developmental activities that is widely found in plants and animals. Photoperiodic flowering in plants is regulated by photosensory receptors including the red/far-red light-receptor phytochromes and the blue/UV-A light-receptor cryptochromes. However, the molecular mechanisms underlying the specific roles of individua...
متن کاملPhotoperiodic effects on dairy cattle: a review.
Since the initial report in 1978 of galactopoietic effects of a photoperiod of 16 h of light:8 h of darkness, numerous studies have confirmed long-day stimulation of milk yield. The endocrine factor(s) responsible for increased milk yield, however, has eluded identification. Recent studies suggest that insulin-like growth factor-I (IGF-I) may mediate the galactopoietic response to long day phot...
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ژورنال
عنوان ژورنال: Nature
سال: 1960
ISSN: 0028-0836,1476-4687
DOI: 10.1038/187096a0