Rikin A
Department of Botany, Oklahoma State University, Stillwater 74078-0293.
Eur J Cell Biol. 1992 Oct;59(1):160-5.
Cotton (Gossypium hirsutum L. cv. Deltapine 50) seedlings grown under light-dark cycles of 12:12 h at 33 degrees C showed rhythmic changes in their resistance to heat shock of 53 degrees C for 40 min. The resistance was maximal at the middle of the light period and declined toward the end of the light period. One more peak of resistance developed in the middle of the dark period and declined toward the end of the dark period. Rhythmic changes in heat resistance persisted under continuous light for 3 cycles, indicating a circadian control. Under continuous light only one phase of resistance developed, lasting from the middle of the subjective night to the middle of the subjective day. The major heat shock proteins (HSPs) synthesized upon 30-min exposure to 40 degrees C, 49 degrees C or 53 degrees C were of 115, 89, 73, and 19 kDa. Their rate of synthesis depended on the inducing temperature, on previous exposure to high temperature and on the time in the light-dark cycle. The time dependency of the induction of certain HSPs persisted under continuous light, indicating a circadian control. No positive correlations was found between the rhythmic changes in heat resistance and the rhythmic changes in the synthesis of any HSP.
在33摄氏度、12小时光照与12小时黑暗循环条件下生长的棉花（陆地棉品种Deltapine 50）幼苗，对53摄氏度热激40分钟的抗性呈现出节律性变化。抗性在光照期中期达到最大值，并在光照期结束时下降。在黑暗期中期又出现一个抗性峰值，并在黑暗期结束时下降。在持续光照下，耐热性的节律性变化持续了3个周期，表明存在昼夜节律调控。在持续光照下，仅出现一个抗性阶段，从主观夜间中期持续到主观白天中期。在暴露于40摄氏度、49摄氏度或53摄氏度30分钟时合成的主要热激蛋白（HSP）为115、89、73和19千道尔顿。它们的合成速率取决于诱导温度、先前的高温暴露以及在光暗循环中的时间。某些热激蛋白诱导的时间依赖性在持续光照下依然存在，表明存在昼夜节律调控。在耐热性的节律性变化与任何热激蛋白合成的节律性变化之间未发现正相关。
