Heterochromatin and genetic conflict
Heterochromatin and genetic conflict
复制标题
异染色质和遗传冲突
DOI：
--
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发表时间：
2016
影响因子：
11.1
通讯作者：
C. Meiklejohn
中科院分区：
文献类型：
--
作者：
C. Meiklejohn
减数分裂是件危险的事。二倍体生物体中的两个等位基因在其宿主个体的生存和繁殖方面具有共同的进化兴趣;然而，一旦它们分离成单倍体配子，这些等位基因就会发现自己竞争传递给下一代（1）。在雄性中，所有四种减数分裂产物发育成功能性配子促进等位基因的进化，从而破坏携带替代等位基因的配子的发育或生存力。扭曲孟德尔分离的系统（因此，分离扭曲因子）通常包含至少两个基因座：一个反式作用驱动基因座（例如编码毒物的基因），其靶向对第二个连锁基因座上的毒物敏感的等位基因（2）。分离扭曲进化的一个主要障碍是要求有毒等位基因与靶基因座上的抗性等位基因紧密连锁;否则，当与敏感等位基因配对时，扭曲基因会自杀（3）。因此，常染色体上的分离畸变体总是与抑制畸变体和靶基因座之间重组的倒位相关。相比之下，Y染色体高度退化的异型性染色体可以促进分离扭曲因子的进化，因为X和Y经常共享很少的同源序列，并且不会沿着它们的沿着大部分或全部长度重组。因此，性染色体分离扭曲，扭曲的性别比例的后代的男性携带他们（因此，性别比例扭曲）预计将经常演变（4）。人群中存在性别比例扭曲因子，选择抗性Y染色体和常染色体抑制因子，恢复男性生育力和平衡的性别比例，并可能导致平衡的多态性或男性生殖系中功能基因座之间的开放式军备竞赛（5）。PNAS最近的一项研究已经确定了果蝇性别比例扭曲所需的基因（6），为这些自私元素使用的遗传和分子机制及其对基因组进化和物种形成的影响提供了新的见解。
Meiosis is a dangerous business. The two alleles in diploid organisms share an evolutionary interest in the survival and reproduction of their host individual; however, as soon as they segregate into haploid gametes, these alleles find themselves competing for transmission to the next generation (1). In males, the development of all four meiotic products into functional gametes fosters the evolution of alleles that disrupt the development or viability of gametes carrying the alternate allele. Systems that distort Mendelian segregation (hence, segregation distorters) typically comprise at least two loci: a trans-acting drive locus (such as a gene that encodes a poison) that targets alleles that are sensitive to the poison at a second, linked locus (2). A major impediment to the evolution of segregation distorters is the requirement that the poisonous allele be tightly linked to resistant alleles at the target locus; otherwise, distorters will commit suicide when paired with a sensitive allele (3). As a result, segregation distorters on autosomes are invariably associated with inversions that suppress recombination between the distorter and target loci. In contrast, heteromorphic sex chromosomes, where the Y chromosome is highly degenerated, can facilitate the evolution of segregation distorters because the X and Y frequently share little homologous sequence and do not recombine along most or all of their length. Thus, sex-chromosome segregation distorters that distort the sex ratio of the progeny of males that carry them (hence, sex-ratio distorters) are predicted to evolve frequently (4). The presence of sex-ratio distorters in populations selects for resistant Y chromosomes and autosomal suppressors that restore male fertility and a balanced sex ratio, and may lead to either balanced polymorphisms or open-ended arms races between loci that function in the male germ line (5). A recent study in PNAS has identified a gene required for sex-ratio distortion in Drosophila simulans (6), providing novel insight into the genetic and molecular mechanisms used by these selfish elements and their effects on genome evolution and species formation.
DOI：
10.1073/pnas.0509809103
发表时间：
2006-06-27
影响因子：
11.1
作者：
Levine, Mia T.;Jones, Corbin D.;Begun, David J.
通讯作者：
Begun, David J.