The possibleprincipal function of neurohypophysial hormones

从海洋到稀释环境的适应构成了生命史上最引人注目的进化转变之一。这种适应已经在多个谱系中进化，但对其机制的研究仅限于那些进化先进的后口动物（脊索动物）和外生动物（甲壳类动物）。在这里，我们研究了高级光藻/软体动物（另一个未被探索的分类群）的体液稳态，以及已知与脊索动物和节肢动物的体液稳态有关的后叶加压素/催产素超家族肽可能对体液稳态的调节。高盐头足类动物（章鱼）从正常盐度（30毫帕）转移到低盐度（20毫帕）后的血淋巴渗透和离子状态表明，与甲壳类动物和硬骨鱼一样，高渗和高渗调节能力持续超过1周。通气频率降低1天后，Na+/K+- atp酶活性在1周后在8个后鳃中的2个中被诱导。Na+/K+- atp酶活性通常与离子运输有关。此外，给章鱼静脉注射1或100 ng/g的章鱼素或头足类加压素/催产素同源物。1天后，章鱼素降低了血淋巴渗透压、钙浓度和尿钠浓度，而不是头孢菌素。这些数据为超离子调控机制的趋同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.