Proper chromosome segregation in meiosis I relies on the formation of connections between homologous chromosomes. Crossovers between homologs provide a connection that allows them to attach correctly to the meiosis I spindle. Tension is transmitted across the crossover when the partners attach to microtubules from opposing poles of the spindle. Tension stabilizes microtubule attachments that will pull the partners toward opposite poles at anaphase. Paradoxically, in many organisms, non-crossover partners segregate correctly. The mechanism by which non-crossover partners become bioriented on the meiotic spindle is unknown. Both crossover and non-crossover partners pair their centromeres early in meiosis (prophase). In budding yeast, centromere pairing is correlated with subsequent correct segregation of the partners. The mechanism by which centromere pairing, in prophase, promotes later correct attachment of the partners to the metaphase spindle is unknown. We used live cell imaging to track the biorientation process of non-crossover chromosomes. We find that centromere pairing allows the establishment of connections between the partners that allows their later interdependent attachment to the meiotic spindle using tension-sensing biorientation machinery. Because all chromosome pairs experience centromere pairing, our findings suggest that crossover chromosomes also utilize this mechanism to achieve maximal segregation fidelity.

减数分裂 I 中正确的染色体分离依赖于同源染色体之间连接的形成。同源物之间的交叉提供了一种连接，使它们能够正确附着到减数分裂 I 纺锤体上。当伴侣从纺锤体的相对两极附着到微管上时，张力就会通过交叉传递。张力稳定了微管附着，将伴侣在后期拉向相反的两极。矛盾的是，在许多生物体中，非交叉伙伴正确分离。非交叉伴侣在减数分裂纺锤体上变成双向的机制尚不清楚。交叉和非交叉伙伴都在减数分裂早期（前期）配对它们的着丝粒。在芽殖酵母中，着丝粒配对与随后伴侣的正确分离相关。前期着丝粒配对促进随后伴侣正确附着到中期纺锤体的机制尚不清楚。我们使用活细胞成像来追踪非交叉染色体的生物定向过程。我们发现着丝粒配对允许在伙伴之间建立连接，从而允许它们随后使用张力感应生物取向机制相互依赖地附着到减数分裂纺锤体上。由于所有染色体对都经历着丝粒配对，因此我们的研究结果表明交叉染色体也利用这种机制来实现最大的分离保真度。