The evolution of species-type specificity in the global DNA sequence organization of mitochondrial genomes
The evolution of species-type specificity in the global DNA sequence organization of mitochondrial genomes
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作者：
Hill, KA;Singh, SM
原核生物基因组和真核生物的核基因组具有物种类型特异性的全局DNA序列组织，主要由最近邻核苷酸关联决定，并且与基因功能和序列长度无关。这一全球结构的决定因素在很大程度上仍然没有确定。线粒体的单系和内共生起源允许研究进化时间和宿主物种类型的影响。原生动物和植物的球形结构不同。(ii)真菌，（iii）藻类，（iv）线虫，（v）棘皮动物。(vi)昆虫和（vii）脊椎动物物种，使用混乱表示和短序列表示措施检查25个完整的线粒体基因组后，线粒体基因组在单核苷酸和二核苷酸表示方面存在偏差，特别是A和T核苷酸以及CC/GG和AG/CT的过度表达。在除一个基因组外的所有基因组中，CG二核苷酸缺乏。二核苷酸的代表性是相似的（i）线粒体基因组更密切饲养的物种，（ii）线粒体基因组和山羊支原体基因组，线粒体基因组的建议祖先，和（iii）不同物种的线粒体基因组，比线粒体和核基因组之间的相同或密切相关的物种。据推测，足够的进化时间允许主机特定的限制，以影响核和线粒体基因组，不同的物种类型的特定限制影响核和线粒体侏儒的全球结构。
Prokaryote genomes and nuclear genomes of eukaryotes have a global DNA sequence organization that is species type specific, determined primarily by nearest-neighbor nucleotide associations, and independent of gene function and sequence length. The determinants of such a global structure have remained largely uncharacterized. The monophyletic and endosymbiotic origin of mitochondria permit examination of the influence of evolutionary time and host species type. Different global structures were seen among (i) protozoan and plant. (ii) fungal, (iii) algal (iv) nematode, (v) echinoderm. (vi) insect, and (vii) vertebrate species following examination of 25 complete mitochondrial genomes using chaos representation and measures of short-sequence representation, The mitochondrial genomes have biases in single-nucleotide and dinucleotide representation, specifically, an overrepresentation of A and T nucleotides and CC/GG and AG/CT dinucleotides and a deficiency of CG dinucleotides, in all but one genome. Dinucleotide representation is similar among (i) mitochondrial genomes of more closely reared species, (ii) mitochondrial genomes and the Mycoplasma capricolum genome, a proposed progenitor of mitochondrial genomes, and (iii) mitochondrial genomes of diverse species, more so than between the mitochondrial and the nuclear genome of the same or a closely related species. It is hypothesized that sufficient evolutionary time has permitted host-specific constraints to affect nuclear and mitochondrial genomes and that different species type specific constraints influence nuclear and mitochondrial gnome global structure.