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首页> 外文期刊>Journal of bacteriology >Unit Cell Hypothesis for Streptococcus faecalis
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Unit Cell Hypothesis for Streptococcus faecalis

机译：粪链球菌的单位细胞假说

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The mass doubling times of exponential-phase cultures of Streptococcus faecalis were varied from 30 to 110 min by omitting glutamine from a defined growth medium and providing different concentrations of glutamate (ranging from 300 to 14 μg/ml). After Formalin fixation, cells were dried by the critical point method, and carbon-platinum replicas were prepared. The surface area and volume of cell poles seen in these replicas were estimated by a computer-assisted, three-dimensional reconstruction technique. It was found that the amount of surface area and volume of poles seen in these replicas were independent of the growth rate of culture from which the samples were taken. These observations were consistent with the unit cell model hypothesis of Donachie and Begg, in which a small number of surface sites would produce a constant amount of new cell surface regardless of the mass doubling time of the culture. However, measurements of the thickness of the cell wall taken from thin sections of the same cells showed that the cell wall increased in thickness as a function of the increase in cellular peptidoglycan content which occurs when the growth rate of this organism is slowed down by a decrease in glutamate concentration. Thus, it would seem that although the size of polar shells made by S. faecalis is invariant with growth rate, the amount of wall precursors used to construct these shells is not.
机译：通过从特定的生长培养基中省略谷氨酰胺并提供不同浓度的谷氨酸盐（范围从300到14μg/ ml），粪链球菌（Stremococcus faecalis）的指数相培养物的质量倍增时间在30到110分钟之间变化。 。福尔马林固定后，通过临界点法干燥细胞，并制备碳-铂复制品。在这些复制品中看到的细胞极的表面积和体积是通过计算机辅助的三维重建技术估算的。发现在这些复制品中看到的表面积和极的数量与取样品的培养物的生长速率无关。这些观察结果与Donachie和Begg的单位细胞模型假说是一致的，在该假说中，无论培养物的质量倍增时间如何，少量表面位点都会产生恒定数量的新细胞表面。然而，从同一细胞的薄切片中获取的细胞壁厚度的测量结果表明，细胞壁的厚度随细胞肽聚糖含量的增加而增加，而细胞肽聚糖含量的增加是由于该生物体的生长速度因细胞生长速度减慢而发生的。降低谷氨酸浓度。因此，看起来尽管 S制成的极壳的大小。粪便的生长速率不变，而用于构建这些壳的壁前体的数量则没有变化。

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