Calcification rate influence on trace element concentrations in aragonitic bivalve shells: Evidences and mechanisms
Calcification rate influence on trace element concentrations in aragonitic bivalve shells: Evidences and mechanisms
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DOI：
10.1016/j.gca.2006.07.019
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发表时间：
2006-10-01
影响因子：
5
通讯作者：
Fontugne, Michel
中科院分区：
文献类型：
--
作者：
Carre, Matthieu;Bentaleb, Ilhem;Fontugne, Michel
钙质生物中的微量元素在古气候研究中有着广泛的应用。然而，控制它们进入软体动物壳的因素仍不清楚。本文研究了秘鲁沿岸文石型海洋双壳类（Mesodesma donacium和Chione subrugosa）贝壳中Sr、Mg、Ba和Mn的系列记录。元素浓度进行了比较，当地的温度和盐度记录。与晶体生长速率G的关系进行了研究，由于良好定义的周期性生长结构提供了一个精确的壳年表。我们的研究结果表明，对于这两个物种，环境参数只有很小的影响，而晶体生长速率强烈影响微量元素的浓度，特别是Sr（解释高达74%的方差）。G和Sr/Ca之间的关系表现出壳之间以及壳内的变化。对于相同的生长速率值，Sr/Ca值在更弯曲的壳段中更高，并且生长速率的影响也更强。我们发现，细胞间和Ca（2+）泵途径不能支持钙化Ca（2+）流量，导致我们提出了一种替代机制，通过钙化外套膜的离子运输，这意味着外套上皮细胞膜上的钙通道的主要作用。在这个新的钙化模型中，Sr/Ca壳比由Ca通道对Sr的选择性决定，这取决于（i）结晶过程施加的电化学电势和（ii）外套膜上皮细胞上每个表面单位的Ca（2+）通道密度。(c)2006年爱思唯尔公司All rights reserved.
Trace elements in calcareous organisms have been widely used for paleoclimatic studies. However, the factors controlling their incorporation into mollusc shells are still unclear. We studied here the Sr, Mg, Ba and Mn serial records in the shells of two aragonitic marine bivalve species: Mesodesma donacium and Chione subrugosa from the Peruvian Coast. The elemental concentrations were compared to local temperature and salinity records. The relationships with crystal growth rate G were investigated thanks to well defined periodic growth structures providing a precise shell chronology. Our results show that for both species, environmental parameters only have minor influence, whereas crystal growth rate strongly influences trace elements concentrations, especially for Sr (explaining up to 74% of the variance). The relationship between G and Sr/Ca exhibits variability among the shells as well as inside the shells. For a same growth rate value, Sr/Ca values are higher in more curved shell sections, and the growth rate influence is stronger as well. We show that intercellular and Ca(2+)-pump pathways cannot support the calcification Ca(2+) flux, leading us to propose an alternative mechanism for ionic transport through the calcifying mantle, implying a major role for calcium channels on mantle epithelial cell membranes. In this new calcification model, Sr/Ca shell ratios is determined by Ca channel selectivity against Sr, which depends (i) on the electrochemical potential imposed by the crystallisation process and (ii) on the Ca(2+)-channel density per surface unit on mantle epithelia. (c) 2006 Elsevier Inc. All rights reserved.