水稻HSPs诱导合成的研究

Study on HSPs of Rice Seedlings

水稻HSPs在37—40℃开始启动合成,在43℃合成量最大。43℃处理0—9.5小时,可诱导合成两组共18种HSPs。第一组8种HSPs在热激后立即启动合成,其分子量大于50kd;第二组10种HSPs在热激处理3.5小时才启动合成,所有低分子量HSPs都集中在这一组。我们认为,HSPs合成的多级调控主要受处理时间制约,而与高于热激诱导临界温度之上的温度变化无关或关系不大。mRNA体外翻译的结果表明水稻热激mRNA是在热激后新合成的。

Rice heat shock proteins (HSPs) start to synthesize at 37-40℃, and the temperature at which synthesis of maximum HSPs occurs is 43℃. Eighteen HSPs classified into two groups are induced respectively from 0 to 9.5 hours after heat shock at 43℃. The first 8 HSPs synthesize immediately after heat shock, and their size are larger than 50Kd; the second 10 HSPs begin to synthesize after 3.5 hr of heat shock. All of low molecular weight (lower than 50Kd) HSPs belong to this group. Multi-regulation of HSPs induction dependent on a gradual temperature increase is observed in maize (Baszcynski et al., 1932; Cooper et al., 1982) and sorghum (Li et al., 1985). Our resuhs are different from theirs. We suggest that multi-regulation of HSPs induction in rice, perhaps including maize and sorghum, depends on the time of heat shock, but not the change of temperatures over the induction threshold. Poly (A)+RNAs of rice seedlings are translated in vitro in a cell-free protein synthesis system from wheat germ. Six extra-proteins are detected in the translated products directed by the poly(A)+RNAs isolated from heat shocked (43℃, 2hr) rice seedlings, but absent in that of its control. This shows that some new mRNAs are synthesized in response to heat shock.