The Circannual Clock in the European Hamster: How Is It Synchronized by Photoperiodic Changes?

摘要: In a seasonal environment, mammals time their reproductive phase so that the offspring are born in spring and summer. Two strategies have evolved to ensure accurate timing of reproduction, but both share common Zeitgeber, changes photoperiod. The axis might be directly controlled, as photoperiodic species, which require input show competence. contrast, circannual species act indirectly, namely, on an endogenous clock then times reproduction. This generates self-sustained rhythms with period length about 1 year, information is only needed synchronize these rhythms. Concerning mechanism imparts message internally, far no differences between been reported. Recent results however, strongly suggest European hamster (Cricetus cricetus) uses fundamentally different than species. latter, photoperiod induces change state via melatonin-dependent pathway, whereas hamsters can synchronized melatonin-independent pathway. Instead, circadian based specific organizational involved. Juvenile use probably pathways: pathway for short-term year birth long-term events next year.