Fachbereich Biologie, Botanik, Johann-Wolfgang-Goethe-Universität, Siesmayerstraße 70, D-6000, Frankfurt/Main, Germany.
Planta. 1980 Jul;149(2):163-9. doi: 10.1007/BF00380878.
In the leaves of rye seedlings (Secale cereale L.) grown at an elevated temperature of 32°C the formation of plastidic 70S ribosomes is specifically prevented. The resulting plastid ribosome-deficient leaves, which are chlorotic in light, represent a system for the identification of translation products of the 80S ribosomes among the chloroplastic proteins. Searching for the primary heat-sensitive event causing the 70S ribosome-deficiency, the thermostability of the chloroplastic capacity for RNA synthesis was investigated. The RNA polymerase activity of isolated normal chloroplasts from 22°-grown rye leaves was not inactivated in vitro at temperatures between 30° and 40°C. The ribosome-deficient plastids purified from bleached 32°-grown leaf parts contained significant RNA polymerase activity which was, however, lower than in functional chloroplasts. After application of [(3)H]uridine to intact leaf tissues [(3)H]uridine incorporation was found in ribosome-deficient plastids of 32°C-grown leaves. The amount of incorporation was similar to that in the control chloroplasts from 22°C-grown leaves. According to these results, it is unlikely that the non-permissive temperature (32°C) causes a general inactivation of the chloroplastic RNA synthesis in rye leaves.
在 32°C 高温下生长的黑麦幼苗（Secale cereale L.）的叶片中，质体 70S 核糖体的形成被特异性阻止。由此产生的质体核糖体缺陷的叶片在光照下呈黄化，这是鉴定叶绿体蛋白中 80S 核糖体翻译产物的一种系统。为了寻找导致 70S 核糖体缺陷的主要热敏事件，研究了分离的正常叶绿体的 RNA 合成能力的耐热性。来自 22°C 生长的黑麦叶片的分离正常叶绿体的 RNA 聚合酶活性在 30°C 至 40°C 之间的体外不会失活。从白化的 32°C 生长叶片部分纯化的核糖体缺陷质体含有显著的 RNA 聚合酶活性，但低于功能叶绿体。将 [(3)H]尿嘧啶应用于完整的叶片组织后，在 32°C 生长叶片的核糖体缺陷质体中发现了 [(3)H]尿嘧啶掺入。掺入量与来自 22°C 生长叶片的对照叶绿体相似。根据这些结果，非许可温度（32°C）不太可能导致黑麦叶片中叶绿体 RNA 合成的普遍失活。
