日本科學(xué)家２５日?qǐng)?bào)告說(shuō)，他們?cè)诿姘湍阁w內(nèi)發(fā)現(xiàn)了８種與染色體數(shù)目異常相關(guān)的基因,。由于人體內(nèi)也存在類(lèi)似基因,，這項(xiàng)成果可能有助于研究染色體數(shù)目異常引起的流產(chǎn)和唐氏綜合征等疾病。
人類(lèi)染色體共有２３對(duì),，４６條,。４６條染色體經(jīng)過(guò)減數(shù)分裂平均分配到形成的精子或卵子中，受精后,，染色體數(shù)目便恢復(fù)到４６條,。約９５％的唐氏綜合征患者由“２１三體”導(dǎo)致，即在卵細(xì)胞減數(shù)分裂過(guò)程中,，一條２１號(hào)染色體不分離,，使受精卵的２１號(hào)染色體增至３條，而不是正常情況下的兩條,。而流產(chǎn)很多情況下也是因?yàn)槿旧w數(shù)目出現(xiàn)異常,。
減數(shù)分裂中會(huì)發(fā)生同源染色體配對(duì)和基因重組，以往的研究發(fā)現(xiàn),，如果不經(jīng)過(guò)基因重組,，染色體就不能正常分離，最終造成精子和卵子染色體數(shù)目異常,。
日本大阪大學(xué)蛋白質(zhì)研究所教授篠原彰等研究人員在２５日的《自然·遺傳學(xué)》雜志網(wǎng)絡(luò)版上發(fā)表文章說(shuō),，他們以染色體數(shù)目異常而不能正常產(chǎn)生孢子（相當(dāng)于精子或卵子）的面包酵母為對(duì)象，研究它們體內(nèi)的基因情況,。
研究人員發(fā)現(xiàn),，這些面包酵母體內(nèi)有８?jìng)€(gè)與染色體異常相關(guān)的基因，其中任何一個(gè)基因出現(xiàn)問(wèn)題,，酵母染色體基因不能重組的概率都會(huì)提高,。他們還發(fā)現(xiàn)，這８?jìng)€(gè)基因合成的蛋白質(zhì)會(huì)結(jié)合成一個(gè)復(fù)合體,，不能形成復(fù)合體的酵母染色體數(shù)目也會(huì)發(fā)生偏差,。
研究人員推測(cè),，這種蛋白質(zhì)復(fù)合體保證染色體基因重組順利進(jìn)行，如果能證實(shí)人類(lèi)的流產(chǎn)等是由這一復(fù)合體功能下降引起的,，將有助于診斷和治療相關(guān)疾病。
生物谷推薦原文提要:
Crossover assurance and crossover interference are distinctly regulated by the ZMM proteins during yeast meiosis
Miki Shinohara, Steve D Oh, Neil Hunter & Akira Shinohara,
Abstract:Meiotic crossing-over is highly regulated such that each homolog pair typically receives at least one crossover (assurance) and adjacent crossovers are widely spaced (interference). Here we provide evidence that interference and assurance are mechanistically distinct processes that are separated by mutations in a new ZMM (Zip, Msh, Mer) protein from Saccharomyces cerevisiae, Spo16. Like other zmm mutants, spo16 cells have defects in both crossing-over and synaptonemal complex formation. Unlike in previously characterized zmm mutants, the residual crossovers in spo16 cells show interference comparable to that in the wild type. Spo16 interacts with a second ZMM protein, Spo22 (also known as Zip4), and spo22 mutants also show normal interference. Notably, assembly of the MutS homologs Msh4 and Msh5 on chromosomes occurs in both spo16 and spo22, but not in other zmm mutants. We suggest that crossover interference requires the normal assembly of recombination complexes containing Msh4 and Msh5 but does not require Spo16- and Spo22-dependent extension of synaptonemal complexes. In contrast, crossover assurance requires all ZMM proteins and full-length synaptonemal complexes.
