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首页> 外文期刊>Molecular and Cellular Biology >Inheritance of extrachromosomal ribosomal DNA during the asexual life cycle of Dictyostelium discoideum: examination by use of DNA polymorphisms.
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Inheritance of extrachromosomal ribosomal DNA during the asexual life cycle of Dictyostelium discoideum: examination by use of DNA polymorphisms.

机译：盘基网柄菌无性生活过程中染色体外核糖体DNA的遗传：利用DNA多态性进行检查。

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摘要

Wild-type isolates of Dictyostelium discoideum exhibited differences in the size of restriction fragments of the extrachromosomal 88-kilobase ribosomal DNA (rDNA) palindrome. Polymorphisms in rDNA also were found among strains derived solely from the NC4 wild-type isolate. These variations involved EcoRI fragments II, III, and V; they included loss of the EcoRI site separating fragments II and V and deletion and insertion of DNA. More than one rDNA form can coexist in the same diploid or haploid cell. However, one or another parental rDNA tended to predominate in diploids constructed, using the parasexual cycle, between haploid NC4-derived strains and haploid wild-type isolates. In some cases, most if not all of the rDNA of such diploids were of one form after ca. 50 generations of growth. Segregant haploids, derived from diploids that possessed predominantly a single rDNA allele, possessed the same allele as the diploid and did not recover the other form. This evidence implies that replication does not proceed from a single chromosomal or extrachromosomal copy of the rDNA during the asexual life cycle of D. discoideum.
机译：盘基网柄菌的野生型分离株显示出染色体外88碱基碱基核糖体DNA（rDNA）回文的限制性片段大小的差异。在仅来源于NC4野生型分离株的菌株中，也发现了rDNA的多态性。这些变异涉及EcoRI片段II，III和V。其中包括分离片段II和V的EcoRI位点丢失以及DNA的缺失和插入。相同的二倍体或单倍体细胞可以共存一种以上的rDNA形式。但是，在单倍体NC4衍生菌株和单倍体野生型分离株之间，使用无性生殖周期构建的二倍体中，一个或另一个亲本rDNA倾向于占主导地位。在某些情况下，此类二倍体的大多数（如果不是全部）rDNA大约是在大约10年后呈一种形式。 50代的成长。分离的单倍体衍生自主要具有单个rDNA等位基因的二倍体，其具有与二倍体相同的等位基因，并且没有回收其他形式。该证据表明，在迪斯科球菌的无性生活周期中，复制不是从rDNA的单个染色体或染色体外复制开始的。

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