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首页> 外文期刊>Protoplasma: An International Journal of Cell Biology >POLYANION-MEDIATED MINERALIZATION-MINERALIZATION IN COCCOLITHOPHORE (PLEUROCHRYSIS CARTERAE) VARIANTS WHICH DO NOT EXPRESS PS2, THE MOST ABUNDANT AND ACIDIC MINERAL-ASSOCIATED POLYANION IN WILD-TYPE CELLS
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POLYANION-MEDIATED MINERALIZATION-MINERALIZATION IN COCCOLITHOPHORE (PLEUROCHRYSIS CARTERAE) VARIANTS WHICH DO NOT EXPRESS PS2, THE MOST ABUNDANT AND ACIDIC MINERAL-ASSOCIATED POLYANION IN WILD-TYPE CELLS

机译：虫卵菌（炭疽菌）中不表达PS2的矿物质中矿化作用的矿化作用-矿化作用在野生型细胞中不表达PS2，这是大多数矿物质和酸性矿物相关的矿化作用

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摘要

Highly acidic macromolecules are postulated intermediates in biomineralization because they sequester large numbers of calcium ions and occur in high concentrations at mineralizing foci in distantly related organisms. The mineral-associated polyanions in the coccolithophore Pleurochrysis carterae are acidic polysaccharides which surround calcite elements on mineralized scales called coccoliths. PS2 is the most abundant and acidic Pleurochrysis polyanion, containing four carboxyl groups per disaccharide repeat. This study examines the mineralizing function of PS2 by analysis of calcium carbonate deposition in PS2-deficient cells. Mineral-deficient Pleurochrysis variants were separated from wild-type cells by density gradient centrifugation and analyzed for PS2 expression. Three independent low-density variants (two spontaneous and one chemically-induced) not expressing PS2 (ps2(-)) were isolated. The mineral content of each ps2(-) variant was less than 5% of the wild-type level. Most ps2(-) coccoliths were unmineralized, but when crystals were present, they occurred on the coccolith rim as in wild-type cells. When ps2(-) rim elements were adequately large and numerous, they displayed the alternating A and B anvil shapes characteristic of wildtype rim elements. Although ps2(-) cells may have defects which affect the expression of cellular components in addition to PS2, correlation of PS2 nonexpression with mineral deficiency in three independent variants supports the hypothesis that PS2 is a functional intermediate in mineral deposition. PS2 may affect the level of Pleurochrysis mineralization by (a) controlling the amount of calcium ions available for mineralization, (b) accelerating the rate of calcite nucleation, or (c) both. However, PS2 does not influence crystal morphology, since the more mature crystals in ps2(-) cells exhibit the anvil-shaped morphology of wild-type crystals. [References: 19]
机译：高酸性大分子被认为是生物矿化中的中间体，因为它们螯合了大量的钙离子，并在远处相关生物的矿化灶中以高浓度存在。球石白屈菜软骨中与矿物相关的聚阴离子是酸性多糖，其围绕方解石元素处于矿化的方解石元素上，被称为石岩。 PS2是最丰富和酸性的Pleurochrysis聚阴离子，每个二糖重复序列包含四个羧基。这项研究通过分析PS2缺陷细胞中碳酸钙的沉积来检查PS2的矿化功能。通过密度梯度离心从野生型细胞中分离出缺乏矿物质的胸膜炎变体，并分析其PS2表​​达。分离了三个不表达PS2（ps2（-））的独立的低密度变体（两个自发的和一个化学诱导的）。每个ps2（-）变体的矿物质含量均低于野生型水平的5％。多数ps2（-）球藻未矿化，但是当存在晶体时，它们像野生型细胞一样出现在球藻的边缘。当ps2（-）轮缘元素足够大且数量众多时，它们会显示出野生型轮缘元素的交替A和B砧形状。尽管ps2（-）细胞可能具有影响PS2以外的细胞成分表达的缺陷，但在三个独立的变体中PS2非表达与矿物质缺乏的相关性支持了PS2是矿物质沉积中功能性中间产物的假设。 PS2可能会通过（a）控制可用于矿化的钙离子的量，（b）加速方解石成核速率或（c）两者来影响胸膜肺炎的矿化水平。但是，PS2不会影响晶体形态，因为ps2（-）细胞中更成熟的晶体表现出野生型晶体的铁砧形形态。 [参考：19]

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