Fennoy Sheila L, Nong Thoa, Bailey-Serres Julia
Department of Botany and Plant Sciences, University of California, Riverside, CA 92521 0124, USA.
Plant J. 1998 Sep;15(6):727-735. doi: 10.1046/j.1365-313X.1998.00249.x.
To investigate the regulation of gene expression in maize ( Zea mays L.) in response to oxygen deprivation (flooding), we quantitated run-on transcription in isolated nuclei, steady-state mRNA accumulation and mRNA loading with ribosomes for seven genes that encode proteins synthesized predominantly in oxygen-deprived roots (anaerobic polypeptides) and seven genes that encode proteins synthesized in aerobic roots (aerobic polypeptides). Run-on transcription of anaerobic polypeptide genes was induced in response to oxygen deprivation and run-on transcription of the aerobic polypeptide genes continued during the stress treatment. The increased accumulation of mRNAs that encode anaerobic polypeptides occurred concomitant with the induction of gene transcription and efficient association of these mRNAs with large polysomes. The steady-state accumulation of aerobic polypeptide mRNAs was within twofold of aerobic levels and in a number of cases fewer ribosomes were loaded per transcript. These results demonstrate that selected synthesis of anaerobic polypeptides involves transcriptional as well as significant post-transcriptional regulation of gene expression. The repression of synthesis of many aerobic polypeptides occurs without interruption of gene transcription and is due to translational regulation and possibly the sequestration of mRNAs on mRNPs. Ribosome loading patterns indicated that this translational control occurs at both initiation and post-initiation phases in a message-specific manner.
为了研究玉米（Zea mays L.）中基因表达对缺氧（水淹）的调控，我们对七个编码主要在缺氧根中合成的蛋白质的基因（厌氧多肽）和七个编码在有氧根中合成的蛋白质的基因（有氧多肽），在分离的细胞核中进行了连续转录定量分析、稳态mRNA积累分析以及mRNA与核糖体的结合分析。厌氧多肽基因的连续转录在缺氧条件下被诱导，而有氧多肽基因的连续转录在胁迫处理期间持续进行。编码厌氧多肽的mRNA积累增加与基因转录的诱导以及这些mRNA与大核糖体的有效结合同时发生。有氧多肽mRNA的稳态积累在有氧水平的两倍以内，并且在许多情况下每个转录本上结合的核糖体较少。这些结果表明，厌氧多肽的选择性合成涉及基因表达的转录以及显著的转录后调控。许多有氧多肽合成的抑制在基因转录未中断的情况下发生，这是由于翻译调控以及可能是mRNA在mRNA结合蛋白上的隔离。核糖体结合模式表明，这种翻译控制以信息特异性的方式发生在起始阶段和起始后阶段。
