Structural and Biological Characterization of Elasmobranch Urotensins

术语“神经分泌”是指某些神经纤维将生物活性物质释放到血流中，然后这些物质能够影响远处靶器官的活动。鱼的脊髓下部含有这样的神经分泌系统。神经合成两种肽(小蛋白)，即尾加压素I和尾加压素II。尾加压素最初是从硬骨鱼中分离出来的，但尽管进行了深入的研究，但人们并不了解它们在这些鱼的生理学中的重要性。康伦博士和哈森博士的实验室正在提出一种新的动物模型，在该模型中研究尿紧张素的生理作用。我们将从一种软骨鱼的脊髓提取液中提纯尾加压素I和II，并确定它们的化学结构。然后，我们将合成几毫克的多肽，以确定它们在角鱼体内的生物学作用。利用在动脉中安装了插管的自由游动的鱼，我们将研究角鱼尾加压素对血压和类固醇产生的影响。角鱼的血液，像鲨鱼家族的其他成员一样，含有非常高浓度的尿素，这对维持鱼的体液和周围海水之间的平衡非常重要。我们将研究尾血管紧张素对角鱼体内尿素和其他血液成分水平的影响。我们将从角鱼的不同器官和血管中制备平滑肌条，并研究尾张力蛋白放松或收缩这些肌肉的能力。最后，我们希望通过用放射性标记标记分子，并确定角鱼体内哪些器官识别和结合多肽，来洞察尾部紧张素的作用部位。通过这种方式，我们希望建立一个关于尾加压蛋白在调节软骨鱼生理过程中的作用的整体图景。这些知识在未来的研究中将是有价值的，这些研究将评估尾肌肽在其他类别脊椎动物中的作用。

The term "neurosecretion" refers to the fact that certain nerve fibers release biologically active substances into the blood stream which are then able to influence the activities of distant target organs. The lower portion of the spinal cord of fishes contains such a neurosecretory system. The nerves synthesize two peptides (small proteins) known as urotensin I and urotensin II. The urotensins were first isolated from bony fishes (teleosts) but despite intensive study, their importance in the physiology of these fish is not understood. The laboratories of Dr. Conlon and Hazon are proposing a new animal model in which to investigate the physiological roles of the urotensins. We will purify urotensin I and II from an extract of the spinal cord of a cartilaginous fish, the European common dogfish and determine their chemical structures. We will then synthesize several milligrams of the peptides in order to determine their biological actions in the dogfish. Using free swimming fish that have been fitted with a cannula in an artery, we will investigate the effects of the dogfish urotensins on blood pressure and on the production of steroids. The blood of the dogfish, like other members of the shark family, contains a very high concentration of urea which is important in maintaining an equilibrium between the fish's body fluids and the surrounding sea water. We will investigate the effects of the urotensins upon the levels of urea and other blood constituents in the dogfish. We will prepare strips of smooth muscle from the various organs and blood vessels of the dogfish and study the abilities of the urotensins either to relax or contract these muscles. Finally, we hope to gain insight into the sites of action of the urotensins by tagging the molecules with a radioactive label and determining which organs in the dogfish recognize and bind the peptides. In this way, we hope to build up an overall picture of the roles of the urotensins in regulating the physiology of a cartilaginous fish. This knowledge will be valuable in future investigations that will assess the roles of the urotensins in other classes of vertebrate.