Several haloarchaea are reported to be pleomorphic, while others exhibit remarkable shapes, such as squares. Recently, Haloferax volcanii was found to alter its morphology during growth. Cells are motile rods in early exponential phase, and immotile plates in stationary phase. It is unknown if this growth phase dependent cell shape alteration is a specific feature of Hfx. volcanii, or conserved amongst haloarchaea. Here, we studied the cell shape and motility of two haloarchaea species Haloarcula hispanica and Haloarcula californiae. With a combination of light and electron microscopy, we observed that both strains undergo a growth phase dependent morphological development, albeit in a slightly different fashion as Hfx. volcanii. For both Haloarcula strains, the cell size is changing throughout growth. Cell shape seems to be related with motility, as highly motile cells on semi-solid agar plates are predominantly rod-shaped. We conclude that the growth phase dependent cell morphology alteration might be a common feature amongst haloarchaea, and that cell shape is generally linked with a motile life style. The conservation of this phenomenon underscores the importance of studies of the molecular mechanisms regulating cell shape in archaea.

中文翻译：

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Haloarcula 的生长阶段依赖性细胞形状


据报道，一些盐古菌是多形的，而另一些则表现出显着的形状，例如正方形。最近发现， Haloferax volcanii在生长过程中会改变其形态。细胞在指数生长期是活动的杆，在静止期是不动的板。目前尚不清楚这种生长阶段依赖性细胞形状改变是否是Hfx 的一个特定特征。火山，或保存在盐古菌中。在这里，我们研究了两种盐古菌的细胞形状和运动性： Haloarcula hispanica和Haloarcula californiae。结合光学和电子显微镜，我们观察到两种菌株都经历了生长阶段依赖的形态发育，尽管与Hfx 的方式略有不同。火山。对于两种Haloarcula菌株，细胞大小在整个生长过程中都在变化。细胞形状似乎与运动性有关，因为半固体琼脂平板上的高运动性细胞主要是杆状的。我们得出的结论是，生长阶段依赖性细胞形态改变可能是盐古菌的共同特征，并且细胞形状通常与活动的生活方式有关。这种现象的保存强调了研究调节古细菌细胞形状的分子机制的重要性。