美國佐治亞大學(xué)的科學(xué)家發(fā)現(xiàn)了一種對細(xì)胞分裂中姐妹染色單體分離起重要作用的蛋白,。研究人員發(fā)現(xiàn),，使這種蛋白沉默會導(dǎo)致染色體非整倍性或數(shù)目異常。
Kelly Dawe及其同事的研究表明,，在減數(shù)分裂的第一個(gè)階段,，決定生殖細(xì)胞或配子形成的細(xì)胞分裂過程是由著絲?？刂频摹Ｖz粒是染色體中的一種蛋白結(jié)構(gòu),，紡錘絲在細(xì)胞分裂期間與之結(jié)合,，從而使染色體分離。研究人員進(jìn)一步說明了抑制著絲粒蛋白MIS12如何導(dǎo)致染色體分離失敗,，并最終使減數(shù)分裂的第一個(gè)階段終止的,。
這些發(fā)現(xiàn)可能會在醫(yī)藥和農(nóng)業(yè)方面具有重要意義。著絲粒非常容易退化和突變,。Dawe說這些發(fā)現(xiàn)或許能解釋“為什么年長的女性生育時(shí)要比較年輕女性更容易出現(xiàn)染色體異常的問題,。”這些發(fā)現(xiàn)還能為從事人工植物染色體研究的科學(xué)家提供幫助。Dawe還指出,，由于MIS12的原因,，早期的人造染色體均在減數(shù)分裂過程中以幾乎同樣的方式失敗。對諸如MIS12等蛋白進(jìn)行修復(fù)或許能修正這些作用,。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature Cell Biology 11, 1103 - 1108 (2009) 16 August 2009 | doi:10.1038/ncb1923
Fused sister kinetochores initiate the reductional division in meiosis I
Xuexian Li1 & R. Kelly Dawe1,2
During meiosis I the genome is reduced to the haploid content by a coordinated reductional division event. Homologous chromosomes align, recombine and segregate while the sister chromatids co-orient and move to the same pole1, 2. Several data suggest that sister kinetochores co-orient early in metaphase I and that sister chromatid cohesion (which requires Rec8 and Shugoshin) supports monopolar orientation. Nevertheless, it is unclear how the sister kinetochores function as single unit during this period. A gene (monopolin)3 with a co-orienting role was identified in Saccharomyces cerevisiae; however, it does not have the same function in fission yeast4 and no similar genes have been found in other species. Here we pursue this issue using knockdown mutants of the core kinetochore protein MIS12 (minichromosome instability 12). MIS12 binds to base of the NDC80 complex, which in turn binds directly to microtubules5, 6, 7. In maize plants with systemically reduced levels of MIS12, a visible MIS12–NDC80 bridge between sister kinetochores at meiosis I is broken. Kinetochores separate and orient randomly in metaphase I, causing chromosomes to stall in anaphase due to normal cohesion, marked by Shugoshin, between the chromatids. The data establish that sister kinetochores in meiosis I are fused by a shared microtubule-binding face and that this direct linkage is required for reductional division.
1 Department of Plant Biology, University of Georgia, Athens, GA 30602, USA.
2 Department of Genetics, University of Georgia, Athens, GA 30602, USA.
