Neurohypophysial hormones of dogfish, Triakis scyllium:: structures and salinity-dependent secretion
Neurohypophysial hormones of dogfish, Triakis scyllium:: structures and salinity-dependent secretion
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DOI：
10.1016/j.ygcen.2004.05.009
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发表时间：
2004-09-01
影响因子：
2.7
通讯作者：
Takei, Y
中科院分区：
文献类型：
--
作者：
Hyodo, S;Tsukada, T;Takei, Y
鲨鱼和鳐利用一种独特的策略来适应高渗海洋环境，通过尿素的积累来维持它们的血浆对周围海水（SW）的轻微高渗。由于神经垂体激素（NHs）是合理的候选人的调节效应，NHs的合成和释放后，鱼类转移到不同的环境盐度进行了研究。分子克隆揭示了三种来自角鲨下丘脑的NH：vasotocin（VT）、asvatocin和一种新的催产素家族肽phasitocin（[Phe（3），Asn（4），Ile（8）]vasotocin）。VT前体由信号肽VT、神经垂体素和和肽素部分组成。相比之下，由于缺乏和肽素部分，asvatocin和phasitocin前体更短，如四足动物和肺鱼中的催产素和中催产素前体的情况，但不同于具有和肽素部分的硬骨鱼异催产素前体。在下丘脑，VTmRNA水平在转移到浓缩（130%）SW 2天后显著增加，而asvatocin和phasitocin的mRNA水平在转移到130%或稀释（60%）SW后没有观察到变化。用高灵敏度和特异性的放射免疫测定法测定的血浆VT浓度随环境盐度的升高而升高。这些结果表明，VT是一个调节效应的角鲨，特别是当角鲨暴露于高渗环境。(C)2004年爱思唯尔公司All rights reserved.
Sharks and rays utilize a unique strategy for adaptation to the hyperosmotic marine environment by maintaining their plasma slightly hyperosmotic to surrounding seawater (SW) through the accumulation of urea. Since neurohypophysial hormones (NHs) are plausible candidates for osmoregulatory effectors, the synthesis and release of NHs were investigated after transfer of fish to different environmental salinities. Molecular cloning revealed three NHs from the hypothalamus of a dogfish, Triakis scyllium: vasotocin (VT), asvatocin, and a novel oxytocin-family peptide, phasitocin ([Phe(3), Asn(4), Ile(8)]vasotocin). The VT precursor consists of a signal peptide, VT, a neurophysin and a copeptin moiety. In contrast, the asvatocin and phasitocin precursors are shorter due to the lack of a copeptin moiety as is the case in oxytocin and mesotocin precursors in tetrapods and lungfish, but different from teleost isotocin precursors that have the copeptin moiety. In the hypothalamus, VT mRNA levels significantly increased after transfer to concentrated (130%) SW for 2 days, while no change was observed in mRNA levels of asvatocin and phasitocin following transfer to either 130% or diluted (60%) SW. The increase in VT mRNA was reflected in the plasma level of peptide; plasma VT concentration measured by highly sensitive and specific radioimmunoassay increased according to elevated environmental salinities. These results suggest that VT is an osmoregulatory effector in dogfish, especially when the dogfish is exposed to a hyperosmotic environment. (C) 2004 Elsevier Inc. All rights reserved.