Nandabalan K, Padayatty J D
Center for Genetic Engineering, Indian Institute of Science, Bangalore.
Biochem Biophys Res Commun. 1989 May 15;160(3):1117-23. doi: 10.1016/s0006-291x(89)80119-6.
Three direct repeats of 320, 340 and 238 nucleotides were detected upstream to the 5' end of the 18S rRNA gene of an rDNA unit present on a 9.8 kb EcoRI fragment of the rice DNA. The primer extension analysis showed that the site of initiation of transcription is in the 1st repeat at an A, the 623rd nucleotide upstream to the 5' end of the 18S rRNA gene. Different stretches of the intergenic spacer DNA linked to the Chloramphenicol acetyl transferase gene were transcribed in the intact nuclei of rice embryos. The S1 nuclease protection analysis of the transcripts using [32P]-labelled Chloramphenicol acetyl transferase gene as the probe showed the presence of multiple promoters for rDNA transcription.
在水稻DNA的一个9.8 kb EcoRI片段上存在的一个rDNA单元的18S rRNA基因5'端上游，检测到320、340和238个核苷酸的三个直接重复序列。引物延伸分析表明，转录起始位点在第一个重复序列中的一个A处，位于18S rRNA基因5'端上游第623个核苷酸处。与氯霉素乙酰转移酶基因相连的不同片段的基因间隔区DNA在水稻胚完整细胞核中被转录。使用[32P]标记的氯霉素乙酰转移酶基因作为探针，对转录本进行S1核酸酶保护分析，结果表明存在多个rDNA转录启动子。
