Evolution of Ureotely in Batrachoidid Fishes

小沃尔什9507239 动物如何排泄氮废物的进化的大致轮廓是相当好理解的。 完全水生动物通常排泄氨作为其主要的含氮废物，因为它们周围的水会 稀释有毒的氨水。 陆生和半陆生动物，为了节约用水，排出含氮废物，如尿素和尿酸， 毒性较低，可安全储存于 更高的浓度。 生产这些 少 然而，有毒化合物是昂贵的，因为它们的能量含量较高。 尽管如此，一种鱼，海湾蟾鱼，最近被证明可以合成和排泄尿素。 这 研究旨在 理解 鱼用来制造尿素的生化途径，它们与陆地生物的相似性，以及它们的遗传特征。 这种能力的基础。 实地研究 将决定这种能力在水生环境中的优势。 初步 结果 指示 环境压力促使鱼产生尿素。 将在实验室和鱼类的自然环境中使用各种生物化学，生理学，分子和现场技术，以确定尿素排泄的合成途径，控制机制和功能意义。 这项研究应该为遗传机制提供独特的见解， 脊椎动物重要生理特征的生理意义和进化。 最终，它可能会导致遗传进步，使鱼类养殖能够产生尿素而不是氨，从而通过减少高密度水产养殖， 的 需要 控制 氨 程度. 如果环境压力是启动尿素生产的触发器，那么丰富的鱼类可能使其成为一种有用的生物测定方法，用于沿海水环境中的生物重要变化。

9507239 Walsh The broad outlines of the evolution of how animals excrete their waste nitrogen are reasonably well understood. Fully aquatic animals typically excrete ammonia as their main nitrogenous waste product because the water surrounding them will dilute the toxic ammonia. Terrestrial and semi- terrestrial animals, in order to conserve water, excrete nitrogenous waste products like as urea and uric acid that are less toxic and can be stored safely at higher concentrations. The production of these less toxic compounds is costly, however, because of their higher energy content. In spite of this expense, one fish, the gulf toadfish, has recently been shown to synthesize and excrete urea. This research is aimed at understanding the biochemical pathways the fish uses to make urea, their similarity to those of terrestrial organisms, and the genetic basis for this ability. Field studies will determine what advantage this ability provides in an aquatic environment. Preliminary results indicate that environmental stress induces the fish to make urea. A variety of biochemical, physiological, molecular and field techniques will be used both in the laboratory and in the fish's natural setting to identify synthetic pathways, control mechanisms, and the functional significance of urea excretion. This research should provide unique insight into the genetic mechanisms, physiological significance and evolution of an important physiological trait in vertebrate animals. Ultimately, it may lead to genetic advances that would enable culture of fish that make urea instead of ammonia that could simplify high-density aquaculture by reducing the need to control ammonia levels. If environmental stress is the trigger that initiates urea production, the abundance of the fish may make it a useful bioassay for biologically im portant changes in coastal water environments.