Studies on prolactin in galliformes

对家禽生产者来说，一个具有相当经济重要性的问题是种鸡的孵化行为（“孵蛋”）的发生。这种行为的特点是筑巢频率增加，卵孵化，卵巢复归，厌食，脂肪和中间代谢的大变化。由于这一特性的表现，由于蛋品生产的损失和预防所需的更密集的劳动/管理程序，造成了巨大的成本。垂体激素，泌乳素（PRL）被认为在孵蛋中起着关键作用，因为血液水平在开始时增加6到10倍，并在整个行为表达过程中保持在高水平。在脊椎动物物种中，已经描述了超过300种PRL的生物作用，但PRL如何参与与生理行为相关的孵化仍是未知的。我们最近注意到，垂体分泌多达8种不同的翻译后修饰形式的PRL（糖基化，磷酸化），这些形式的比例在鸡和火鸡的生命周期中变化很大。值得注意的是，在孵化行为和胚胎发生后期，修饰形式占主导地位（bbb75 %）。这是一个出乎意料的结果，因为哺乳动物prl通常与受体的结合亲和力降低，并且更快地从血液中清除。禽PRL受体在生命周期的特定阶段可能在特定组织中被这些改变的PRL激活。为了研究PRL的作用，我们计划1)利用RNA干扰敲低PRL的表达2)纯化各种亚型并测试受体激活3)继续对该基因和其他候选基因进行遗传分析，这些候选基因可用于标记辅助选择以降低种鸡的孵蛋率。

A problem of considerable economic importance to the poultry producer is the occurrence of incubation behavior ("broodiness") in breeder hens. This behavior is characterized by increased nesting frequency, incubation of eggs, involution of the ovary, anorexia, adipsea and large changes in intermediary metabolism. As a result of the expression of this trait, substantial costs are incurred due to both the loss of egg production and to the more intensive labour/management procedures that are required for prevention. The pituitary hormone, prolactin (PRL) is thought to play a key role in broodiness since blood levels increase 6 to 10 fold at the onset and are maintained at high levels throughout the expression of the behavior. Among vertebrate species, greater than 300 biological actions of PRL have been described but how PRL is involved in the physio-behavioural repertoire associated incubation is unknown. We have recently noted that up to 8 different post-translationally modified forms of PRL (glycosylation, phosphorylation) are secreted by the pituitary and the ratio of these forms varies greatly during the life cycle of chickens and turkeys. Notably, the modified forms are dominant (>75 %) during incubation behavior and during the late stages of embryogenesis. This is an unexpected result since mammalian PRLs generally have reduced binding affinity to the receptor and are more rapidly cleared from the blood. The avian PRL receptor may be activated in specific tissues differently at specific stages of the life cycle by these altered PRLs. In order to study, the effects of PRL we plan 1) to knock down expression of PRL using RNA interference 2) to purify the various isoforms and test receptor activation 3) to continue genetic analysis of this and other candidate genes which can be used for marker assisted selection to reduce broodiness in breeder hens.