Birkenmeyer L, Sugisaki H, Ray D S
Nucleic Acids Res. 1985 Oct 11;13(19):7107-18. doi: 10.1093/nar/13.19.7107.
DNA minicircles found within the kinetoplast of the trypanosomatid Crithidia fasciculata, like those of most other kinetoplastid species, are heterogeneous in sequence. The pattern of minicircle DNA fragments generated by cleavage of kinetoplast DNA with various restriction enzymes has been used to demonstrate this heterogeneity. Here we describe a strain of Crithidia fasciculata in which more than 90% of the DNA minicircles exhibit a common pattern of restriction enzyme cleavage sites. A map of cleavage sites within this major minicircle DNA class is presented for seven restriction enzymes with hexanucleotide recognition sequences. Sequence homogeneity at an even finer level is reflected in minicircle DNA digestion patterns generated by restriction enzymes with tetranucleotide recognition sites. Partial DNA sequence analysis of multiple clones from the major minicircle class shows nearly complete homogeneity at the nucleotide level. The existence of a near homogeneous complement of DNA minicircles in Crithidia should facilitate the study of their replication in this organism.
在锥虫克氏锥虫动质体中发现的DNA小环，与大多数其他动质体物种的情况一样，其序列是异质的。用各种限制性内切酶切割动质体DNA所产生的小环DNA片段模式已被用于证明这种异质性。在此，我们描述了一种克氏锥虫菌株，其中超过90%的DNA小环表现出一种常见的限制性内切酶切割位点模式。针对七种具有六核苷酸识别序列的限制性内切酶，给出了该主要小环DNA类别的切割位点图谱。由具有四核苷酸识别位点的限制性内切酶产生的小环DNA消化模式反映了更精细水平上的序列同质性。对来自主要小环类别的多个克隆进行的部分DNA序列分析表明，在核苷酸水平上几乎完全同质。克氏锥虫中近乎同质的DNA小环互补体的存在应有助于研究它们在该生物体中的复制。
