Collaborative Research: The Evolution of Endocrine Function; Discovering the Hormonal Control of Osmoregulation in Basal Vertebrates

所有生物体都必须调节其内部的盐和水含量，以正常运作和生存。 在更复杂的动物中，如脊椎动物，激素及其结合的受体是参与调节盐和水运输的关键信号分子。 鱼类与水直接接触，它们必须积极地从淡水中吸收盐，并积极地将其分泌到海水中，以便能够调节内部的盐浓度。 迄今为止，对盐调节激素控制的研究仅限于对高级鱼类的研究。 本计画将研究七鳃鳗与鲟鱼两种基本脊椎动物体内盐分调节的荷尔蒙控制。 研究人员将研究生长激素和催乳素，这两种由脑垂体分泌的激素，以及它们的受体是如何被外部盐度改变的。这项研究将确定这些激素对七鳃鳗和鲟鱼耐受外部盐度变化能力的影响。 这些研究的结果将产生关于这些激素的功能进化的见解，这反过来又可用于提高鱼类的农业生产和入侵七鳃鳗的管理。 研究结果将很快被转移到比较内分泌学和生理学的教科书中，发表在同行评议的期刊上，并在科学会议上分享。由该奖项支持的研究将调查水生脊椎动物中调节激素的功能进化。我们目前对水生脊椎动物中垂体调节的激素控制的理解几乎完全来自高级硬骨鱼（硬骨鱼），并且没有关于垂体激素如何控制基底脊椎动物中垂体调节的信息。目前已经确定，催乳素（PRL）是大多数硬骨鱼在淡水（FW）中生存的关键，生长激素（GH），至少在某些谱系中，促进海水（SW）中的生长调节。七鳃鳗，作为基础脊椎动物，和chondrosteans（包括鲟鱼），作为基础硬骨鱼，具有相同的神经调节策略硬骨鱼（即，保持几乎恒定的水平的血浆离子，而不管外部盐度），但目前还没有任何信息是否PRL或GH发挥神经调节的七鳃鳗或chondrosteans的作用。有强有力的证据表明，七鳃鳗只有一个成员的PRL/GH家族的垂体激素（GH），使他们特别重要的这些研究。我们的具体目标是：1）研究七鳃鳗生长激素及其受体对盐度变化的反应，2）研究七鳃鳗生长激素对盐度的调节作用，3）研究鲟鱼生长激素和泌乳素对盐度的调节作用。对于每一个物种，我们将研究FW和SW之间的相互转移的生理和内分泌反应的时间过程。我们将利用重组技术，使七鳃鳗生长激素，以开发同源的放射免疫和放射受体测定，并确定其在体内和体外的调节作用。

All living organisms must regulate their internal salt and water content to function routinely and survive. In more complex animals, such as vertebrates, hormones and the receptors to which they bind are critical signaling molecules involved in regulation of salt and water transport. Fish are in direct contact with water, and they must actively take up salts from freshwater and actively secrete them in seawater to be able to regulate internal salt concentrations. To date research on the hormonal control of salt regulation has been limited to studies on advanced fish species. This project will examine the hormonal control of salt regulation in two basal vertebrates, lamprey eel and sturgeon. The researchers will examine how growth hormone and prolactin, two hormones secreted by the pituitary gland, and their receptors are altered by external salinity. This research will determine the effect of these hormones on the ability of lamprey and sturgeon to tolerate changes in external salinity. The results of these studies will yield insights about the functional evolution of these hormones, which in turn could be applied to enhancing agricultural production of fish and management of invasive lamprey. The results will be rapidly transferred to textbooks in comparative endocrinology and physiology, published in peer-reviewed journals, and shared at scientific meetings. Studies supported by this award will investigate the functional evolution of osmoregulatory hormones in aquatic vertebrates. Our current understanding of the hormonal control of osmoregulation in aquatic vertebrates comes almost entirely from advanced bony fish (teleosts), and there is no information on how pituitary hormones control osmoregulation in basal vertebrates. It is now well-established that prolactin (PRL) is critical for survival of most teleosts in freshwater (FW) and that growth hormone (GH), at least in some lineages, promotes osmoregulation in seawater (SW). Lamprey, as basal vertebrates, and chondrosteans (including sturgeon), as basal bony fish, have the same osmoregulatory strategy as teleosts (namely, maintaining nearly constant levels of plasma ions irrespective of external salinity), yet there is currently no information on whether PRL or GH play a role in osmoregulation of either lamprey or chondrosteans. There is strong evidence that lamprey possess only one member of the PRL/GH family of pituitary hormones (GH), making them especially critical for these studies. Our specific aims are: 1) to determine the response of GH and GH receptor to salinity change in lamprey; 2) to determine the osmoregulatory actions of GH in lamprey; and 3) to determine the osmoregulatory roles of GH and PRL in sturgeon. For each species we will examine the time course of physiological and endocrine responses to reciprocal transfers between FW and SW. We will utilize recombinant technology to make lamprey GH in order to develop homologous radioimmuno- and radioreceptor- assays, and determine its osmoregulatory actions in vivo and in vitro.