The role of calcium and magnesium in the concrete tubes of the sandcastle worm
The role of calcium and magnesium in the concrete tubes of the sandcastle worm
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DOI：
10.1242/jeb.02759
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发表时间：
2007-04-15
影响因子：
2.8
通讯作者：
Waite, J. Herbert
中科院分区：
文献类型：
--
作者：
Sun, ChengJun;Fantner, Georg E.;Waite, J. Herbert
沙堡蠕虫Phragmatopoma californica通过将大量的沙粒与建筑器官分泌的水泥粘在一起来建造丘状珊瑚礁。水泥由蛋白质加上大量的钙和镁组成，不以任何矿物质形式投入。本研究检查了钙和镁的消耗对骨水泥的结构和机械性能的影响。通过EDTA螯合去除二价离子导致骨水泥结构部分塌陷，骨水泥从二氧化硅表面脱落。力学性能测试包括砂粒抗拔力、管材抗压强度和水泥粘结力。EDTA处理减少了60%的砂粒拉拔力和管抗压强度的50%，相对于控制。EDTA降低最大粘附力和能量耗散的水泥高达一个数量级。钙和镁耗尽的骨水泥不能通过再次暴露于离子来恢复。结果表明，二价离子在维持Phragmatopoma水泥的结构和粘性方面起着复杂和多功能的作用。
Sandcastle worms Phragmatopoma californica build mound-like reefs by sticking together large numbers of sand grains with cement secreted from the building organ. The cement consists of protein plus substantial amounts of calcium and magnesium, which are not invested in any mineral form. This study examined the effect of calcium and magnesium depletion on the structural and mechanical properties of the cement. Divalent ion removal by chelating with EDTA led to a partial collapse of cement architecture and cement dislodgement from silica surfaces. Mechanical properties examined were sand grain pull-out force, tube resistance to compression and cement adhesive force. EDTA treatment reduced sand grain pull-out forces by 60% and tube compressive strength by 50% relative to controls. EDTA lowered both the maximal adhesive force and energy dissipation of cement by up to an order of magnitude. The adhesiveness of calcium- and magnesium-depleted cement could not be restored by re-exposure to the ions. The results suggest that divalent ions play a complex and multifunctional role in maintaining the structure and stickiness of Phragmatopoma cement.