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首页> 外文期刊>Journal of bacteriology >Conservation and variation of nucleotide sequences within related bacterial genomes: Escherichia coli strains.
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Conservation and variation of nucleotide sequences within related bacterial genomes: Escherichia coli strains.

机译：相关细菌基因组内核苷酸序列的保守和变异：大肠杆菌菌株。

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摘要

Changes in the patterns produced by annealing restriction endonuclease digests of bacterial genomes with probe deoxyribonucleic acids (DNAs) containing small portions of a bacterial genome provide sensitive indicator of the degree of nucleotide sequence relatedness that exists in localized regions of the genomes of closely related bacteria. We have used five probe DNAs to explore the relatedness of parts of the genomes of six laboratory Escherichi coli strains. A range in in the amount of variability in the positions of restriction enzyme cleavage sites in the selected portions of the genomes was found. Portions of the genome that are believed to be inacative were more variable than portions that contained functional genes: the sites in and near regions of homology to phage lambda DNA in the genome showed the greatest variability. These regions probably represent remnants of cryptic prophages. Variability was assessed pairwise among four of the E. coli strains and ranged from 5 to > 25% base pair substitutions in the lambda-related regions. In contrast, the endonuclease cleavage sites in the trp, tna, lac, thy regions, and one other as-yet-unidentified segment of the genome were more highly conserved. It seems likely that these sites lie in genetic locations that are subject to functional constraints.
机译：通过用细菌基因组的一小部分探针脱氧核糖核酸（DNA）退火细菌基因组的限制性核酸内切酶消化而产生的模式变化，提供了紧密相关细菌基因组局部区域中核苷酸序列相关程度的敏感指标。我们使用了五个探针DNA来探索六个实验室大肠杆菌菌株的基因组各部分的相关性。发现在基因组的选定部分中限制酶切割位点的位置的可变性的量的范围。被认为是非活性的基因组部分比包含功能基因的部分更具可变性：基因组中与噬菌体λDNA同源的区域内和附近的位点显示出最大的变异性。这些区域可能代表着隐秘的预言。在四个大肠杆​​菌菌株中成对评估变异性，在λ相关区域中碱基对取代的范围为5％至> 25％。相反，在trp，tna，lac，thy区域和基因组的另一个尚未鉴定的区段中的核酸内切酶切割位点更加保守。这些位点似乎位于受功能限制的遗传位置。

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