Nickells R W, Browder L W, Wang T I
Department of Biological Sciences, University of Calgary, Alta., Canada.
Biochem Cell Biol. 1989 Oct;67(10):687-95. doi: 10.1139/o89-103.
We have further characterized the heat shock response of Xenopus laevis embryos. Xenopus embryos respond to heat shock by consistently synthesizing four major heat shock proteins (hsps) of 62, 70, 76, and 87 kilodaltons. In addition to these hsps, heat-shocked embryos also exhibit the synthesis of several minor hsps. The synthesis of these hsps is often variable. We have monitored the effects of different temperatures and lengths of heat shock on the pattern and intensity of hsp synthesis. In general, the four major hsps are induced more strongly at higher temperatures and during increasing intervals of heat shock. The temperature and duration of heat shock can affect the synthesis of the minor hsps, however. Some hsps are synthesized at lower temperatures only (i.e., below 37 degrees C), whereas others are synthesized only at higher temperatures (i.e., above 37 degrees C). We have extensively examined the characteristics of hsp 35 synthesis, one of the most variably synthesized hsps. This hsp is characteristically synthesized at temperatures above 35 degrees C and usually during the first 40 min of heat shock, after which it becomes undetectable. In some experiments, its synthesis is restimulated during later intervals of heat shock. Hsp 35 is also under developmental regulation. It is not synthesized by heat-shocked embryos until the late blastula to early gastrula stage. After this brief period of inducibility, its synthesis is dramatically reduced in mid- to late gastrulae, but reappears in heat-shocked neurulae. We have previously demonstrated that hsp 35 is related to the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The induction of hsp 35 synthesis is inversely correlated with the constitutive levels of GAPDH specific activity. In this paper we document further correlations between the synthesis of hsp 35 and GAPDH specific activity during early Xenopus development.
我们进一步研究了非洲爪蟾胚胎的热休克反应。非洲爪蟾胚胎对热休克的反应是持续合成四种主要的热休克蛋白（hsps），分子量分别为62、70、76和87千道尔顿。除了这些热休克蛋白外，热休克胚胎还会合成几种次要的热休克蛋白。这些热休克蛋白的合成通常是可变的。我们监测了不同温度和热休克时长对热休克蛋白合成模式和强度的影响。一般来说，在较高温度和热休克时间增加的过程中，四种主要热休克蛋白的诱导作用更强。然而，热休克的温度和持续时间会影响次要热休克蛋白的合成。一些热休克蛋白仅在较低温度下（即低于37摄氏度）合成，而其他热休克蛋白仅在较高温度下（即高于37摄氏度）合成。我们广泛研究了热休克蛋白35合成的特性，它是合成变化最大的热休克蛋白之一。这种热休克蛋白的特征是在高于35摄氏度的温度下合成，通常在热休克的前40分钟内合成，之后就检测不到了。在一些实验中，在热休克的后期阶段其合成会再次被刺激。热休克蛋白35也受发育调控。直到囊胚晚期到原肠胚早期，热休克胚胎才会合成它。在这段短暂的可诱导期之后，在原肠胚中期到晚期其合成会显著减少，但在热休克的神经胚中又会重新出现。我们之前已经证明热休克蛋白35与糖酵解酶甘油醛-3-磷酸脱氢酶（GAPDH）有关。热休克蛋白35合成的诱导与GAPDH比活性的组成水平呈负相关。在本文中，我们进一步记录了非洲爪蟾早期发育过程中热休克蛋白3�合成与GAPDH比活性之间的相关性。
