Université Montpellier 2, Equipe Adaptation Ecophysiologique et Ontogénèse, UMR5119 EcoSyM, UM1-2-CNRS-IRD-Ifremer, cc 092, Place E. Bataillon, 34095, Montpellier cedex 05, France.
Cell Tissue Res. 2013 Jul;353(1):87-98. doi: 10.1007/s00441-013-1622-x. Epub 2013 Apr 25.
The ontogeny of osmoregulatory organs was studied in two geographically isolated populations of the palaemonid shrimp Macrobrachium amazonicum, one originating from the Amazon estuary (A) and the other from inland waters of the Pantanal (P) in northeastern and southwestern Brazil, respectively. A previous investigation had shown that the estuarine population is able to hypo-osmoregulate in seawater, whereas the hololimnetic inland population has lost this physiological function. In the present study, the structural development of the branchial chamber and excretory glands and the presence of Na(+)/K(+)-ATPase (NKA) were compared between populations and between larval and juvenile stages after exposure to two salinities representing hypo- and hypertonic environments. In the newly hatched zoea I stage of both populations, gills were absent and NKA was localized along the inner epithelium of the branchiostegite. In intermediate (zoea V) and late larval stages (decapodids), significant differences between the two populations were observed in gill development and NKA expression. In juveniles, NKA was detected in the gills and branchiostegite, with no differences between populations. At all developmental stages and in both populations, NKA was present in the antennal glands upon hatching. The strong hypo-osmoregulatory capacity of the early developmental stages in population A could be linked to ion transport along the inner side of the branchiostegite; this seemed to be absent or weak in population P. The presence of fully functional gills expressing NKA appears to be essential for efficient hyper-osmoregulation in late developmental stages during successful freshwater adaptation and colonization.
我们研究了两个地理隔离的美姑对虾（Macrobrachium amazonicum）种群的渗透压调节器官的个体发生，一个种群来自亚马逊河口（A），另一个来自巴西北部潘塔纳尔（P）的内陆水域。先前的研究表明，河口种群能够在海水中进行低渗调节，而全淡水内陆种群已经失去了这种生理功能。在本研究中，我们比较了两个种群以及暴露在两种盐度（代表低渗和高渗环境）后的幼虫和幼体阶段之间的鳃腔和排泄腺的结构发育以及钠离子/钾离子-ATP 酶（NKA）的存在。在两个种群的刚孵化的幼体 I 期，都没有出现鳃，NKA 定位于鳃弓的内上皮。在中间（幼体 V）和晚期幼虫（十足幼体）阶段，两个种群的鳃发育和 NKA 表达存在显著差异。在幼体阶段，NKA 存在于鳃和鳃弓中，两个种群之间没有差异。在所有发育阶段和两个种群中，NKA 都存在于触角腺中。A 种群早期发育阶段的强烈低渗调节能力可能与沿鳃弓内侧面的离子转运有关；而在 P 种群中，这种转运似乎不存在或很弱。在成功适应淡水并定居的晚期发育阶段，具有表达 NKA 的完全功能的鳃的存在对于高效的高渗调节似乎是必不可少的。
