Fraser James A, Heitman Joseph
Department of Molecular Genetics and Microbiology, Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, USA.
Mol Microbiol. 2004 Jan;51(2):299-306. doi: 10.1046/j.1365-2958.2003.03874.x.
Sexual reproduction enables organisms to shuffle two parental genomes to produce recombinant progeny, and to purge the genome of deleterious mutations. Sex is conserved in virtually all organisms, from bacteria and fungi to plants and animals, and yet the mechanisms by which sexual identity are established share both conserved general features and are remarkably diverse. In animals, sexual identity is established by dimorphic sex chromosomes, whereas in fungi a specialized region of the genome, known as the mating-type locus, governs the establishment of cell type identity and differs in DNA sequence between cells of different mating-types. Recent studies on the mating-type loci of fungi and algae reveal features shared with the mammalian X and Y chromosomes, suggesting that these represent early steps in the evolution of sex chromosomes.
有性生殖使生物体能够混合两个亲本基因组以产生重组后代，并清除基因组中的有害突变。从细菌、真菌到植物和动物，性在几乎所有生物体中都是保守的，然而，性身份确立的机制既具有保守的一般特征，又显著多样。在动物中，性身份由二态性性染色体确立，而在真菌中，基因组的一个特殊区域，即交配型位点，控制细胞类型身份的确立，并且在不同交配型的细胞之间DNA序列不同。最近对真菌和藻类交配型位点的研究揭示了与哺乳动物X和Y染色体共有的特征，这表明这些代表了性染色体进化的早期步骤。
