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以基因组克隆Rim2 5 6 9为代表 ,分析了该家族中转座酶编码亚组的分子结构 ,同时对Rim2因子在染色体和不同水稻品种之间的差别分布情况进行了研究。序列分析表明 ,Rim2 5 6 9具有完整的 16 bp的末端颠倒重复序列 (TIRs)、若干正向和反向的 16 bp的亚末端重复 (STRs)以及插入位点 3 bp的同向重复。它的TIRs上具有保守序列CACTG ,有别于以往报告的CACTA转座子。该因子含有一个编码区 ,与已报告的Rim2cDNA的ORF基本一致 ,其预测编码蛋白与CAC TA转座子编码的转座酶TNP2和TNPD有低度的同源性。该亚组的其它因子的分子结构均与Rim2 5 6 9的相似 ,但这些因子预测ORF长度上存在着差异 ,反映了结构上的多样性。对检索到的Rim2因子的定位作图表明 ,它们在已测序拼接完成的第 1、4和 10号染色体上呈不均匀分布 ,以着丝点附近的分布频率为最高。PCR反应显示 ,Rim2编码因子在品种之间存在着编码序列多态性。
The genomic clone Rim2 5 6 9 was used as a representative to analyze the molecular structure of transposase coding subgroups in this family. At the same time, the distribution of Rim2 between chromosomes and different rice varieties was also studied. Sequence analysis showed that Rim2 5 6 9 has a complete 16 bp inverted terminal repeat (TIRs), a number of forward and reverse 16 bp sub-terminal repeats (STRs), and a 3 bp homologous repeat at the insertion site. It has conserved sequence CACTG on TIRs, which is different from the previously reported CACTA transposon. This factor contains a coding region that is essentially identical to the reported ORF of Rim2 cDNA, which predicts a low degree of homology to the transposase TNP2 and TNPD encoded by the CAC TA transposon. The molecular structures of the other factors in this subgroup are similar to those of Rim2 5 6 9, but these factors predict differences in ORF length and reflect structural diversity. Mapping of the retrieved Rim2 loci showed that they were unevenly distributed on chromosomes 1, 4 and 10 after the completion of the sequencing splicing, with the highest distribution frequency near the centromere. The PCR reaction showed that there was coding sequence polymorphism in the Rim2 coding factor between cultivars.