The cationic composition and pH in the moulting fluid of Porcellio scaber (Crustacea, Isopoda) during calcium carbonate deposit formation and resorption
The cationic composition and pH in the moulting fluid of Porcellio scaber (Crustacea, Isopoda) during calcium carbonate deposit formation and resorption
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DOI：
10.1007/s00360-007-0200-5
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
A. Ziegler
中科院分区：
文献类型：
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作者：
A. Ziegler
在蜕皮之前，陆地等足目动物从后角质层吸收碳酸钙(CaCO3)，并将其储存在胸骨沉积物中。这些小球主要由无定形碳酸钙(ACC)小球组成，这些小球在胸骨前上皮和旧角质层之间的蜕皮间隙中发育。蜕皮液中的离子，包括矿物质沉积所需的离子，由胸骨前上皮细胞从血淋巴输送到蜕皮间隙。蜕皮液的阳离子成分可能会影响矿物沉积，并可能提供有关胸骨上皮细胞离子转运活性的信息。这项研究介绍了在羽化后期和蜕皮内，胸骨前部蜕皮液中无机阳离子的浓度。阳离子含量最丰富的是Na+，其次是镁、钙、钾。这些离子的浓度在各阶段之间没有明显的变化，而从初生期的矿物沉积到蜕皮内的再吸收之间的平均pH分别在8.2到6.9个单位之间变化。跨上皮电位的测量表明，钙在胸骨前上皮中被动移动的驱动力很小。结果表明，镁离子可能在ACC的形成中起作用，pH变化对CaCO3的沉淀和溶解有贡献。
Before moulting, terrestrial isopods resorb calcium carbonate (CaCO3) from the posterior cuticle and store it in sternal deposits. These consist mainly of amorphous calcium carbonate (ACC) spherules that develop within the ecdysial space between the anterior sternal epithelium and the old cuticle. Ions that occur in the moulting fluid, including those required for mineral deposition, are transported from the hemolymph into the ecdysial space by the anterior sternal epithelial cells. The cationic composition of the moulting fluid probably affects mineral deposition and may provide information on the ion-transport activity of the sternal epithelial cells. This study presents the concentrations of inorganic cations within the moulting fluid of the anterior sternites during the late premoult and intramoult stages. The most abundant cation is Na+followed by Mg2+, Ca2+and K+. The concentrations of these ions do not change significantly between the stages whereas the mean pH changed from 8.2 to 6.9 units between mineral deposition in late premoult, and resorption in intramoult, respectively. Measurements of the transepithelial potential show that there is little driving force for passive movements of calcium across the anterior sternal epithelium. The results suggest a possible role of magnesium ions in ACC formation, and a contribution of pH changes to CaCO3precipitation and dissolution.