Photoperiodic Regulation of a Circannual Rhythm

几乎所有的动物都会经历身体结构的显著变化， 功能和行为，使他们能够适应，并生存， 季节性变化的自然环境带来的艰辛 的 Karsch博士的研究目标是了解 季节的变化调节季节性繁殖， 可逆的生育和不育的过程。 他选择了 以家养母羊为模型系统。 在这个物种中， 季节性繁殖的过程是由一个 神经内分泌活动的自我维持的内源性节律。 白天长度的变化提供了时间线索， 这种内源性节律的阶段性变化与周期性变化， 环境 卡什博士将决定短暂的一天 在乏情期给予光周期提示是有效的， 长日照光周期提示是否无效， 在繁殖季节。 特定的光周期信息 将通过将褪黑激素输注到pinelectomized 羊 褪黑激素是一种只由松果体分泌的激素 在晚上，它使动物能够说出夜晚有多长 也就是一天的持续时间 这项研究的结果 应该会带来对一个巨大的基本问题的新见解 生物学意义和实际意义： 生育能力。 结果也将更广泛地适用于 各种各样的生理、代谢和行为节奏 其在许多情况下形成自适应机制的组成部分 动物 对这些过程的理解应该有深刻的 对濒危物种生殖生物学的影响， 是季节性繁殖 由于研究将在国内进行， 羊，调查结果将直接影响生产的 食品和纤维工业。

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 goal of Dr. Karsch's research is to understand the means by which the changing seasons regulate seasonal reproduction, a natural process of reversible fertility and infertility. He has selected domestic female sheep as the model system. In this species, the process of seasonal reproduction 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. Dr. Karsch will determine whether a short day photoperiodic cue is effective when given during anestrus, and whether a long day photoperiodic cue is ineffective when given during the breeding season. The specific photoperiodic messages will be restored by infusion of melatonin into pinelectomized sheep. Melatonin is a hormone secreted by the pineal gland only at night, and it enables the animal to tell how long the night is and thus the duration of the day. The outcome of this 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 reproductive biology of endangered species that are seasonal breeding. Since the studies will be done in domestic sheep, the findings will have a direct bearing on production in the food and fiber industries.