Post-Ecdysial Change in the Permeability of the Exoskeleton of the Blue Crab, Callinectes sapidus
Post-Ecdysial Change in the Permeability of the Exoskeleton of the Blue Crab, Callinectes sapidus
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蓝蟹 Callinectes sapidus 蜕皮后外骨骼渗透性的变化
DOI：
10.1651/08-3053.1
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
R. Dillaman
中科院分区：
文献类型：
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作者：
D. L. Williams;S. Modla;R. Roer;R. Dillaman
摘要甲壳类动物必须用新的、更大的外骨骼替换旧的外骨骼，以便生长和分化。在这个过程中，一个新的（前蜕皮）角质层沉积在旧角质层下面。由于旧角质层的分解产物已被报道从旧角质层中去除，并穿过新角质层和皮下组织进入血淋巴，因此推测前蜕皮角质层是可渗透的。然而，也有报道称，蜕皮间角质层是一种高度不可渗透的结构，可防止水分和离子从角质层流失到外部环境中。本研究的目的是确定任何变化的时间在角质层的蓝蟹，Callinectes sapidus，从蜕皮前的早期蜕皮期间。为了测试渗透性的任何变化进行了试点研究片的背鳃角质层从后期蜕皮前（D4）和早期蜕皮后的螃蟹（15分钟，2小时，12小时和18小时后蜕皮）使用3H2O和一个Ussing室。与蜕皮前角质层相比，使用更有限的蜕皮后时间过程（蜕皮后0、5、10、15和30分钟）进行额外的渗透性研究，监测对硝基苯酚（PNP）穿过角质层的运动。从这些研究的结果，以及洗出的研究，使用组织预装PNP和染色后蜕皮角质层与OsO4表明，上表皮经历了一个过渡或蜕皮后不久，使其不透水和小分子。虽然这种转变的确切机制尚不清楚，但很明显，蜕皮后早期上表皮渗透性的改变允许形成阻止渗透和离子交换的屏障，允许产生显著的静水压力，并为钙化提供合适的微环境。
Abstract Crustaceans must replace their old exoskeleton with a new, larger one in order to grow and differentiate. During that process a new (pre-exuvial) cuticle is deposited beneath the old cuticle. Since breakdown products from the old cuticle have been reported to be removed from the old cuticle and transported across the new cuticle and hypodermis into the hemolymph, the preexuvial cuticle is presumed to be permeable. However, it has also been reported that intermolt cuticle is a highly impermeable structure that prevents loss of water and ions from the cuticle to the external environment. This study was designed to determine the timing of any change in the permeability of the cuticle of the blue crab, Callinectes sapidus, from the period just preceding ecdysis through the early postmolt period. To test for any changes in permeability pilot studies were performed on pieces of dorsobranchial cuticle from late premolt (D4) and early postmolt crabs (15 min, 2 h, 12 h and 18 h post-ecdysis) using 3H2O and an Ussing chamber. Additional permeability studies were done monitoring the movement of p-nitrophenol (pNP) across the cuticle using a more restricted post-exuvial time course (0, 5, 10, 15 and 30 min. post-ecdysis) as compared to premolt cuticle. Results from these studies as well as wash-out studies using tissues pre-loaded with pNP and staining of 1 h post-molt cuticle with OsO4 suggest that the epicuticle undergoes a transition at or soon after ecdysis that renders it impermeable to water and small molecules. While the precise mechanism for this transition is unknown, it is clear that the resultant alteration in epicuticle permeability during early post-ecdysis allows for the formation of a barrier that prevents osmotic and ionic exchange, allows for the generation of significant hydrostatic pressure, and provides a suitable microenvironment for calcification.