Pseudohomothallism and evolution of the mating-type chromosome in Neurospora tetrasperma.
Pseudohomothallism and evolution of the mating-type chromosome in Neurospora tetrasperma.
复制标题
四子脉脉孢菌的拟同位性和交配型染色体的进化。
DOI：
10.1093/genetics/143.2.789
复制
发表时间：
1996
期刊：
影响因子：
3.3
通讯作者：
Natvig,DO
中科院分区：
文献类型：
--
作者：
Merino,ST;Nelson,MA;Jacobson,DJ;Natvig,DO
脉孢子囊菌的子囊孢子通常含有交配型自形核(A型和A型)，导致自育异核体(一种称为假同源生殖的有性繁殖)。偶尔的同核自不育品系(无论是大动脉A)表现为异源，原则上是提供。具有兼性异交手段的四种植物。这项研究被认为是对中华按蚊种群生物学的一项调查。四种类型以评估品系内异核体水平(杂合度)。意想不到的结果是，交配型染色体和常染色体表现出非常不同的进化模式，显然是因为交配型染色体之间的重组受到抑制。对野生自育品系交配型染色体的序列分析表明，兄弟姐妹间存在高度的遗传变异。相比之下，兄弟姐妹DNA的常染色体上的序列显示出几乎完全的同质性。来自不同地点的菌株在Aandamating型染色体上的不同单倍型组合的保守性进一步表明，在相当长的进化时期内没有重组。然后对重组的抑制。四乳突型染色体是一种能确保高频率自我繁殖的染色体，它为研究哺乳动物性染色体的进化提供了一个有趣的平行和可能的模型。
Ascospores ofNeurospora tetraspermanormally contain nuclei of both mating-type idiomorphs (aandA), resulting in self-fertile heterokaryons (a type of sexual reproduction termed pseudohomothallism). Occasional homokaryotic self-sterile strains (eitheraorA) behave as heterothallics and, in principle, provideN. tetraspermawith a means for facultative outcrossing. This studywas conceived as an investigation of the population biology ofN. tetraspermato assess levels of intrastrain heterokaryosis (heterozygosity). The unexpected result was that the mating-type chromosome and autosomes exhibited very different patterns of evolution, apparently because of suppressed recombination between mating-type chromosomes. Analysis of sequences on the mating-type chromosomes of wild-collected self-fertile strains revealed high levels of genetic variability between siblingAandanuclei. In contrast, sequences on autosomes of siblingAandanuclei exhibited nearly complete homogeneity. Conservation of distinct haplotype combinations onAandamating-type chromosomes in strains from diverse locations further suggested an absence of recombination over substantial periods of evolutionary time. The suppression of recombination on theN. tetraspermamating-type chromosome, expected to ensure a high frequency of self fertility, presents an interesting parallel with, and possible model for studying aspects of, the evolution of mammalian sex chromosomes.