Photoperiodic Regulation of Seasonal Reproduction

几乎所有动物的身体结构、功能和行为都发生了显著的变化，使它们能够适应并生存在随季节变化的自然环境的艰苦环境中。该项目的总体目标是了解家羊这一具有世界重要性的动物的季节性繁殖规则。最近的研究表明，绵羊的季节性繁殖过程是由自我维持的神经内分泌活动的内源性节律自发产生的。白天长度的变化提供了时间线索，允许这种内生节奏随着环境的周期性变化而适当调整。该研究计划的具体目标是确定日长的年度周期中提供导致适当时间安排的繁殖季节的时间信息的部分，并澄清传递这种信息的机制。这项研究的结果应该会导致对一个具有巨大生物学意义和实践重要性的基本问题的新见解：生育率的调节。这些结果也将更广泛地适用于各种生理、代谢和行为节律，这些节律构成了许多动物适应机制的组成部分。对这些过程的了解应该对食物生产和人类营养以及季节性繁殖的野生或濒危物种的生殖生物学产生深远的影响。

Virtually all animals undergo marked changes in body structure, function and behavior which enable them to adapt to, and survive, the hardships of a seasonally changing natural environment. The overall goal of the program is to understand the regulation of seasonal reproduction in an animal of world-wide importance, the domestic sheep. It has become clear through recent research that the process of seasonal reproduction in sheep is generated spontaneously by a self-sustained endogenous rhythm of neuroendocrine activity. Changes in day length provide time cues which permit appropriate phasing of this endogenous rhythm with cyclic changes in the environment. The specific goal of the research program is to define those portions of the annual cycle of day length which provide the temporal information leading to an appropriately timed breeding season, and to clarify the mechanisms by which this information is conveyed. The outcome of the research should lead to new insights into a fundamental problem of enormous biological significance and practical importance: the regulation of fertility. The results will also be more broadly applicable to a wide variety of physiological, metabolic and behavioral rhythms which form an integral part of the adaptive mechanisms in many animals. An understanding of these processes should have profound implications to the production of food and human nutrition as well as the reproductive biology of wild or endangered species that are seasonal breeders.