Serrano Laetitia, Grousset Evelyse, Charmantier Guy, Spanings-Pierrot Céline
Laboratoire Génome, Populations, Interactions, Adaptation, UMR 5171, Equipe Adaptation Ecophysiologique et Ontogenèse, Université Montpellier II, Place E. Bataillon, CP 092, 34095 Montpellier Cédex 05, France.
J Histochem Cytochem. 2004 Sep;52(9):1129-40. doi: 10.1369/jhc.4A6292.2004.
We studied the ontogeny of the eyestalk structure and of the L-CHH and d-Phe3-CHH synthesis in the X-organ/sinus gland (XO/SG) complex by light microscopy and immunocytochemistry in the freshwater crustacean Astacus leptodactylus. The optic ganglia start to differentiate in embryos at EI 190 microm (EI: eye index; close to 410 microm at hatching). At EI 270 microm, the three medullae (externa, interna, and terminalis) and the lamina ganglionaris are present and are organized as in the adult eyestalk. The L-CHH was localized in perikarya of neuroendocrine cells, in their tracts, and in SG from the metanauplius stage to the adult. The d-Phe3-CHH was visualized in XO perikarya, in their tracts and in SG of embryos from EI 350 microm and in all later studied stages. Co-localization of both CHH stereoisomers always occurred in the d-Phe3-CHH-producing cells. These results show that the synthesis of CHH enantiomers starts during the embryonic life in A. leptodactylus, and that the d-isomer is synthesized later than its L-counterpart. We discuss the post-translational isomerization as a way to generate hormonal diversity and the putative relation between d-Phe3-CHH synthesis and the ability to osmoregulate, occurring late during the embryonic life of Astacus leptodactylus.
我们通过光学显微镜和免疫细胞化学技术，研究了淡水甲壳类动物细指螯虾X器官/窦腺（XO/SG）复合体中眼柄结构以及L型CHH和d-Phe3-CHH合成的个体发育过程。在胚胎期，当眼指数（EI）达到190微米时（EI：眼指数；孵化时接近410微米），视神经节开始分化。当EI达到270微米时，三个髓质（外髓、内髓和终髓）和神经节层已经存在，并且其组织形式与成年眼柄相同。从无节幼体阶段到成年阶段，L型CHH定位于神经内分泌细胞的胞体、其神经纤维束以及窦腺中。在眼指数达到350微米的胚胎的XO胞体、其神经纤维束以及窦腺中，以及在所有后续研究阶段中，均观察到了d-Phe3-CHH。两种CHH立体异构体的共定位总是发生在产生d-Phe3-CHH的细胞中。这些结果表明，在细指螯虾胚胎期就开始合成CHH对映体，并且d型异构体的合成晚于其L型对应物。我们讨论了翻译后异构化作为产生激素多样性的一种方式，以及d-Phe3-CHH合成与渗透调节能力之间的假定关系，这种关系发生在细指螯虾胚胎发育后期。
