Photoperiodic Regulation of Seasonal Reproduction

事实上，所有动物的身体结构、功能和行为都会发生显著的变化，以适应和生存季节性变化的自然环境。该计划的总体目标是了解一种具有世界重要性的动物——家养羊的季节性繁殖规律。通过最近的研究已经清楚地表明，绵羊的季节性繁殖过程是由自我维持的内源性神经内分泌活动节律自发产生的。白天长度的变化提供了时间线索，使这种内源性节律与环境的周期性变化相适应。该研究计划的具体目标是确定每年白昼长度周期中提供时间信息的部分，这些信息导致适当的繁殖季节，并阐明这些信息传达的机制。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际重要性的基本问题的新见解：生育调节。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。对这些过程的了解将对粮食生产和人类营养以及作为季节性繁殖者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.