Rao V S, Brand J J, Myers J
Departments of Botany and Zoology, The University of Texas, Austin, Texas 78712.
Plant Physiol. 1977 May;59(5):965-9. doi: 10.1104/pp.59.5.965.
The phenomenon of cold shock in Anacystis nidulans has been explored further in terms of loss of viability and immediate and subsequent metabolic effects. Cold shock was observed also in two closely related strains in which unsaturated fatty acid contents are also known to be low and temperature-dependent. Loss of viability was maximum for cells grown at temperatures above 40 C (<10(-4) survivors after 5 min at 0 C) but became negligibly small for cells grown below 34 C. Development of the cold-sensitive condition after transfer 25 --> 39 C was slow and comparable to rate of growth; development of the insensitive condition after transfer 39 --> 25 C was rapid, implying rapid in situ alteration. An immediate metabolic effect, observed as a decrease in rate of photosynthetic O(2) evolution measured at growth temperature, was less severe than loss of viability. Continued light incubation under growth conditions led to slow decay in rate of O(2) evolution accompanied by loss of membrane chlorophyll. The multiple effects which comprise the cold shock syndrome appear to be membrane-related phenomena and thereby provide an experimental probe of normal membrane function.
已从活力丧失以及即时和后续代谢效应方面对集胞藻（Anacystis nidulans）中的冷休克现象进行了进一步探究。在另外两种密切相关的菌株中也观察到了冷休克现象，已知这两种菌株中不饱和脂肪酸含量也较低且与温度有关。对于在40℃以上温度生长的细胞，活力丧失最大（在0℃下5分钟后存活细胞<10⁻⁴），但对于在34℃以下温度生长的细胞，活力丧失可忽略不计。在25℃→39℃转移后冷敏感状态的发展缓慢，与生长速率相当；在39℃→25℃转移后不敏感状态的发展迅速，这意味着原位快速改变。在生长温度下测量的光合O₂释放速率下降这一即时代谢效应，不如活力丧失严重。在生长条件下持续光照培养导致O₂释放速率缓慢下降，并伴有膜叶绿素的丧失。构成冷休克综合征的多种效应似乎是与膜相关的现象，从而为正常膜功能提供了一个实验探针。
