Search for the genes responsible for adaptation to marine environments: osmoregulatory hormone genes

海洋是生命的发源地，一般来说是生物生存的舒适环境。然而，海水的高渗透压对等离子体渗透压仅为海水的三分之一的海洋硬骨鱼造成了沉重的负担。在这种高渗环境下，激素在体液调节中起核心作用。尽管加压素/缩后叶催产素被认为是适应陆地环境的必要激素，但迄今为止，在海水适应中起关键作用的主要激素尚未被确定。因此，我们在河豚和medaka的基因组数据库中寻找na -挤出激素，它们在硬骨鱼中非常多样化。例如，钠肽（NPs）在硬骨鱼中有7个类似物，在哺乳动物中有3个，其中一种NPs，心房NP (ANP)，被发现是硬骨鱼中主要的海水适应激素。ANP通过抑制饮用及随后肠道对Na和Cl的吸收来降低海鳗血浆钠浓度，从而促进海水适应。肾上腺髓质素在哺乳动物中是一种向水和na分泌的激素，但在硬骨鱼中形成一个独立的5个亚科（AM1、2、3、4和5）。此外，我们在哺乳动物中发现了AM2和AM5。AM2对哺乳动物的体液调节有重要的中枢作用，如抑制饮酒和催产素分泌，而AM5可能与免疫系统的调节有关。AM2和AM5具有较强的致冷和抗利尿作用，可能促进硬骨鱼对海水的适应。观阴林是一种肠道激素，通过将氯离子分泌到肠腔中，使水与肠腔平行流动，从而导致哺乳动物腹泻。在硬骨鱼中，观音林还能刺激肠道中Cl的分泌。然而，分泌的Cl离子被Na和K通过Na-K- 2cl共转运体吸收，另外两个渗透细胞从管腔进入体内，导致水的吸收。因此，观音林可能通过获取更多的水分来应对脱水，从而促进海水适应。综上所述，通过JSPS支持的为期三年的项目，我们可以确定促进海水适应的主要激素。少

The sea, from which the life originates, is generally a comfortable environment for living organism. However, high osmotic pressure of seawater poses a heavy burden to marine teleosts that have plasma osmotic pressure only one third of seawater. Hormones play central roles in body fluid regulation in such hyperosmotic environmental. However, major hormones that play key roles in seawater adaptation have not been identified thus far, although vasopressin/vasotocin is identified as an essential hormone to adapt to the terrestrial environment. Therefore, we search for Na-extruding hormones in the genome database of pufferfish and medaka, and they are much diversified in teleost fish. For instance, natriuretic peptides (NPs) have 7 paralogs in teleost, much more than 3 in mammals, and one of the NPs, atrial NP (ANP), is found to be a major seawater-adapting hormone in teleost fish. ANP decreases plasma Na concentration in seawater eels by inhibiting drinking and subsequent absorption of Na … More Cl by the intestine, thereby promoting seawater adaptation. Adrenomedullin is a water and Na-extruding hormone in mammals, but it forms an independent subfamily of 5 paralogs (AM1, 2, 3, 4 and 5) in teleost fish. Further, we discovered AM2 and AM5 in mammals. AM2 has potent central actions for body fluid regulation such as inhibition of drinking and oxytocin secretion in mammals, while AM5 may be related to regulation of immune system. AM2 and AM5 have a potent dipsogenic and antidiuretic effects, so that these hormones may promoter seawater adaptation in teleost fish. Guanylin, an intestinal hormone, causes diarrhea in mammals by secreting Cl ions into the lumen of the intestine, with which water moves in parallel. In teleost fish, guanylin also stimulates Cl secretion in the intestine. However, the secreted Cl ions are absorbed with Na and K through Na-K-2Cl co-transporter, two more osmolytes moves from the lumen into the body, resulting in absorption of water. Therefore, guanylin may promote seawater adaptation by acquiring more water to cope with dehydration. In summary, we could identify major hormones that promote seawater adaptation through the three-year project supported by JSPS. Less