The possibleprincipal function of neurohypophysial hormones

从海洋环境到稀薄环境的适应构成了生命历史上最戏剧性的进化转变之一。这种适应已经在多个谱系中进化，但对这种机制的研究仅限于那些使用进化先进的后口动物(脊索动物)和蜕皮虫(甲壳类)的物种。在这里，我们研究了高级Lophotrochozoa/软体动物，其他未被探索的类群的体液动态平衡，以及已知与脊索动物和节肢动物的体液动态平衡有关的加压素/催产素超家族多肽对其可能的调节。从正常海水(30ppt)转移到低盐度(20ppt)后，常盐头足类(Octopus Ocellatus)的血淋巴渗透和离子状态表明，与甲壳类和硬骨鱼一样，高渗透压和高渗透压调节能力持续了一周以上。在换气次数减少1天的同时，8个后鳃中有2个在1周后诱导了Na/K-ATPase活性，该活性普遍与离子转运有关。此外，章鱼静脉注射1或100 ng/g的八叶加压素或头孢菌素、头足类加压素/催产素的直系物。治疗1d后，八叶加压素降低血淋巴渗透压，降低血淋巴钙浓度和尿钠浓度，而不是头孢妥英。这些数据为高离子调节机制的收敛进化和保守分子的协调提供了证据。

Acclimation from marine to dilute environments constitutes among the most dramatic evolutionary transitions in the history of life. Such adaptations have evolved in multiple lineages, but studies of the mechanisms are limited to those using evolutionarily advanced Deuterostome (chordates) and Ecdysozoa (crustaceans). Here we examined the body-fluid homeostasis in the advanced Lophotrochozoa/mollusc, the other unexplored taxa, and its possible regulations byvasopressin/oxytocin superfamily peptides known to be implicated in fluid homeostasis in Chordata and Arthropoda. The hemolymph osmotic and ionic status in the euryhaline cephalopod (Octopus ocellatus) following transfer from normal seawater (30 ppt) to low (20 ppt) salinity indicate the hyperosmo- and hyperiono-regulatory abilities for more than 1 week, as in crustaceans and teleost fish. While ventilation frequency decreased by 1 day, Na+/K+-ATPase activity, which has been implicated in ion transport generally, was induced in two of the eight posterior gills after 1 week. Furthermore, the octopuses were intravenously injected with 1 or 100 ng/g octopressin or cephalotocin, cephalopod vasopressin/oxytocin orthologs. After 1 day, octopressin, not cephalotocin, decreased the hemolymph osmolality and Ca concentrations as well as urinary Na concentrations. These data provide evidence for convergent evolution in the hyper-ionoregulatory mechanisms and the coordination by conserved molecules.