Giles R, Manne S, Mann S, Morse D E, Stucky G D, Hansma P K
Biol Bull. 1995 Feb;188(1):8-15. doi: 10.2307/1542062.
The nacre (mother-of-pearl) that forms the irridescent inner layers of mollusc shells is a highly ordered microlaminate composite of aragonite crystals and biopolymers with a strength and fracture resistance that far exceed those of the mineral crystals themselves. The processes governing the biofabrication of this material by the secretory cells of the mantle are complex and only partially understood. We have used the atomic force microscope (AFM) to investigate the aqueous solution conditions under which mineral growth can occur on the nacreous layer of the shell of the bivalve mollusc Atrina sp. In situ imaging of the mature nacre surface exposed to a pH-controlled environment of natural seawater with added carbonate ions reveals that inorganic overgrowth of aragonite can occur within the ranges of pH and inorganic ion concentrations found in the molluscan extrapallial fluid from which the mineral is produced during biological shell growth. Thus, we posit that once nucleation has occurred, nacreous tablets could grow inorganically in the extrapallial space; the role of proteins and other macromolecules may be limited to initiating growth or controlling morphology through selective adsorption and spatial constraint on the growing crystal.
构成软体动物贝壳内层彩虹色的珍珠质（珍珠母）是一种由文石晶体和生物聚合物组成的高度有序的微层状复合材料，其强度和抗断裂性远远超过矿物晶体本身。由外套膜分泌细胞对这种材料进行生物制造的过程很复杂，目前仅部分为人所知。我们使用原子力显微镜（AFM）来研究在何种水溶液条件下，双壳类软体动物Atrina sp.贝壳的珍珠质层上会发生矿物生长。对暴露于添加了碳酸根离子的天然海水的pH值受控环境中的成熟珍珠质表面进行原位成像显示，在生物贝壳生长过程中产生矿物的软体动物外套膜外液中的pH值和无机离子浓度范围内，文石的无机过度生长可能会发生。因此，我们假定一旦发生成核，珍珠质片层可能会在外套膜外空间中无机生长；蛋白质和其他大分子的作用可能仅限于通过对生长晶体的选择性吸附和空间限制来启动生长或控制形态。
