Bannon G A, Calzone F J, Bowen J K, Allis C D, Gorovsky M A
Nucleic Acids Res. 1983 Jun 25;11(12):3903-17. doi: 10.1093/nar/11.12.3903.
Heterologous probes for yeast H4 and H3 histone genes have been used to study the corresponding histone mRNAs in growing and starved Tetrahymena. Histone mRNAs in both physiological states are polyadenylated. Two types of H4 protein and two types of H3 protein have previously identified in Tetrahymena. Two size classes of H4 messages and three classes of H3 messages have been detected by northern analyses. Southern blot analysis indicate that the number of different kinds of H3 and H4 genes is the same or slightly greater than the number of different messages, suggesting that each message is derived from a different gene. Growing cells have -30 times more histone mRNA than starved cells, even though their total mRNA content is only 4 times greater. The relative abundance of different H4 and H3 messages in growing and starved cells is different, demonstrating that the different messages for a particular type of histone are regulated non-coordinately. In starved cells the presence of a single size class of H3 messages correlates with the preferential synthesis of a previously described macronuclear-specific H3 variant. The fraction of histone messages loaded in growing and starved cells is the same as for bulk mRNAs, and the relative concentrations of the multiple messages for H4 and H3 are the same in polysomal and total RNAs of each cell type. These observations suggest that histone synthesis in Tetrahymena is controlled largely at the level of message abundance, and that very little, if any, control occurs at the translational level.
已使用酵母H4和H3组蛋白基因的异源探针来研究生长中的和饥饿的四膜虫中的相应组蛋白mRNA。处于两种生理状态下的组蛋白mRNA均被多聚腺苷酸化。先前已在四膜虫中鉴定出两种类型的H4蛋白和两种类型的H3蛋白。通过Northern分析检测到两种大小类别的H4信息和三类H3信息。Southern印迹分析表明，不同种类的H3和H4基因的数量与不同信息的数量相同或略多，这表明每条信息都来自不同的基因。生长中的细胞的组蛋白mRNA比饥饿细胞多约30倍，尽管它们的总mRNA含量仅高4倍。生长中的细胞和饥饿细胞中不同H4和H3信息的相对丰度不同，这表明特定类型组蛋白的不同信息受到非协调调节。在饥饿细胞中，单一大小类别的H3信息的存在与先前描述的大核特异性H3变体的优先合成相关。生长中的细胞和饥饿细胞中加载的组蛋白信息的比例与大量mRNA相同，并且每种细胞类型的多核糖体RNA和总RNA中H4和H3的多条信息的相对浓度相同。这些观察结果表明，四膜虫中的组蛋白合成主要在信息丰度水平上受到控制，并且在翻译水平上几乎没有控制（如果有控制的话）。
