Adaptation of the nematode Caenorhabditis elegans to extreme osmotic stress
Adaptation of the nematode Caenorhabditis elegans to extreme osmotic stress
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DOI：
10.1152/ajpcell.00381.2003
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发表时间：
2004-04-01
影响因子：
5.5
通讯作者：
Strange, K
中科院分区：
文献类型：
--
作者：
Lamitina, ST;Morrison, R;Strange, K
控制渗透平衡的能力对细胞生命是必不可少的。细胞内的渗透平衡是通过无机离子和有机渗透调节物质的积累和丢失来维持的。虽然在许多细胞类型中已经广泛研究了β-内酰胺酶的调节，但在我们对这一重要过程的分子理解中存在重大差距。由于其众多的实验优势，秀丽隐杆线虫提供了一个强大的模型系统来表征动物细胞增殖调控的遗传基础。因此，我们的特点是蠕虫的能力，以适应极端渗透压。蠕虫暴露于高盐生长琼脂会导致快速收缩。在含有高达200 mM NaCl的琼脂上存活正常。当在200 mM NaCl上生长2周时，蠕虫能够在含有高达500 mM NaCl的琼脂上存活良好。HPLC分析表明，在200 mM NaCl琼脂上生长的线虫中，有机渗透剂甘油的水平增加15至20倍。甘油在暴露于高渗应激后3 h开始蓄积，并在24 h达到峰值。甘油蓄积主要由代谢前体的合成介导。与这一发现一致，高渗增加甘油3-磷酸脱氢酶的转录表达，甘油3-磷酸脱氢酶是酵母中高渗诱导的甘油合成的限速酶。适应高盐的蠕虫膨胀，然后当暴露于低盐琼脂时恢复到它们的初始体积。在从高渗应激恢复期间，甘油水平迅速下降，甘油排泄增加约5倍。我们的研究首次描述了C. elegans，为动物细胞凋亡调控的遗传和功能基因组学分析提供了基础。
The ability to control osmotic balance is essential for cellular life. Cellular osmotic homeostasis is maintained by accumulation and loss of inorganic ions and organic osmolytes. Although osmoregulation has been studied extensively in many cell types, major gaps exist in our molecular understanding of this essential process. Because of its numerous experimental advantages, the nematode Caenorhabditis elegans provides a powerful model system to characterize the genetic basis of animal cell osmoregulation. We therefore characterized the ability of worms to adapt to extreme osmotic stress. Exposure of worms to high-salt growth agar causes rapid shrinkage. Survival is normal on agar containing up to 200 mM NaCl. When grown on 200 mM NaCl for 2 wk, worms are able to survive well on agar containing up to 500 mM NaCl. HPLC analysis demonstrated that levels of the organic osmolyte glycerol increase 15- to 20-fold in nematodes grown on 200 mM NaCl agar. Accumulation of glycerol begins 3 h after exposure to hypertonic stress and peaks by 24 h. Glycerol accumulation is mediated primarily by synthesis from metabolic precursors. Consistent with this finding, hypertonicity increases transcriptional expression of glycerol 3-phosphate dehydrogenase, an enzyme that is rate limiting for hypertonicity- induced glycerol synthesis in yeast. Worms adapted to high salt swell and then return to their initial body volume when exposed to low-salt agar. During recovery from hypertonic stress, glycerol levels fall rapidly and glycerol excretion increases approximately fivefold. Our studies provide the first description of osmotic adaptation in C. elegans and provide the foundation for genetic and functional genomic analysis of animal cell osmoregulation.