Finding the correct partner: the meiotic courtship.
Finding the correct partner: the meiotic courtship.
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作者：
Naranjo T
同源染色体通常在减数分裂入口处分离；它们如何配对是减数分裂过程的未解之谜之一。同源物之间间距的减少使得染色体相互作用的发生成为可能，从而导致同源性检测和二价体的形成。在许多生物体中，端粒引导的染色体运动将同源物聚集在一起。减数分裂早期染色质构象变化产生的额外运动也可能促进同源接触。用于减数分裂研究的生物体显示出令人惊讶的多种同源性检测策略。在双翅目动物中，同源染色体在大部分发育过程中保持配对。配对似乎是作为启动子和抑制配对基因之间的平衡而出现的。一些真菌、植物和动物使用基于重组相互作用的机制。导致同源搜索的其他机制与重组无关，并且需要专门的配对位点。在秀丽隐杆线虫中，每条染色体都携带一个由染色体特异性 DNA-蛋白质复合物组成的配对中心，而在裂殖酵母裂殖酵母中，sme2 位点编码介导同源识别的减数分裂特异性非编码 RNA。此外，错配校正也发挥着重要作用，特别是在多倍体中，多倍体进化出抑制非同源相关（同源）染色体之间配对的遗传系统。
Homologous chromosomes are usually separated at the entrance of meiosis; how they become paired is one of the outstanding mysteries of the meiotic process. Reduction of spacing between homologues makes possible the occurrence of chromosomal interactions leading to homology detection and the formation of bivalents. In many organisms, telomere-led chromosome movements are generated that bring homologues together. Additional movements produced by chromatin conformational changes at early meiosis may also facilitate homologous contacts. Organisms used in the study of meiosis show a surprising variety of strategies for homology detection. In dipterans, homologous chromosomes remain paired throughout most of development. Pairing seems to arise as a balance between promoter and suppressor pairing genes. Some fungi, plants and animals, use mechanisms based on recombinational interactions. Other mechanisms leading to homology search are recombination-independent and require specialized pairing sites. In the worm Caenorhabditis elegans, each chromosome carries a pairing center consisting of a chromosome-specific DNA-protein complex, and in the fission yeast Schizosaccharomyces pombe, the sme2 locus encodes a meiosis-specific non-coding RNA that mediates on homologous recognition. In addition, mismatch correction plays a relevant role, especially in polyploids, which evolved genetic systems that suppress pairing between non-homologous related (homoeologus) chromosomes.