減數(shù)分裂是真核生物有性繁殖所必需的一個(gè)生命過(guò)程，其重組導(dǎo)致了父母本染色體之間DNA的交換,，從而增加后代的遺傳差異。減數(shù)分裂重組主要包括DNA雙鏈斷裂,、加工,、合成和連接，最終形成交換和非交換,。其中,，DNA合成是減數(shù)分裂重組中必不可少的一個(gè)環(huán)節(jié)。
當(dāng)前減數(shù)分裂的重組模型只包括了DNA前導(dǎo)鏈的合成,，而DNA合成相關(guān)基因在減數(shù)分裂中的作用還未有報(bào)道,。迄今為止，減數(shù)分裂重組是否需要DNA后隨鏈的合成更不清楚,。本研究主要通過(guò)分子遺傳學(xué)和細(xì)胞生物學(xué)等方法,，分析了擬南芥DNA后隨鏈合成的重要因子RFC1，發(fā)現(xiàn)該基因突變顯著降低了植物的育性,、減少了同源二價(jià)體形成的數(shù)目,、非同源染色體間有明顯的相互作用、形成大量多價(jià)體,，最終導(dǎo)致染色體的不正常分離,。將rfc1與重組不同通道的相關(guān)突變體雜交進(jìn)行遺傳分析，表明RFC1作用在交換的主要通道干涉敏感性途徑,。此外,，突變體中剩下的交換表現(xiàn)出干涉不敏感，且依賴(lài)于該途徑中起主要作用的MUS81的功能,。
由此提出,，減數(shù)分裂重組主要通道中間體dHJ的形成需要DNA后隨鏈的合成，同時(shí)糾正了近30年來(lái)科學(xué)家一直認(rèn)為,，減數(shù)分裂重組DNA合成環(huán)節(jié)環(huán)節(jié)只需要DNA前導(dǎo)鏈,。由于RFC1在多種生物中都有高度保守的單拷貝同源基因，暗示dHJ的形成需要DNA后隨鏈的合成是一個(gè)保守的環(huán)節(jié),。相關(guān)結(jié)果發(fā)表在PLoS Genetics上,。（生物谷Bioon.com）
doi: 10.1371/journal.pgen.1003039
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The DNA Replication Factor RFC1 Is Required for Interference-Sensitive Meiotic Crossovers in Arabidopsis thaliana
Wang Y, Cheng Z, Huang J, Shi Q, Hong Y, Copenhaver GP, Gong Z, Ma H.
During meiotic recombination, induced double-strand breaks (DSBs) are processed into crossovers (COs) and non-COs (NCO); the former are required for proper chromosome segregation and fertility. DNA synthesis is essential in current models of meiotic recombination pathways and includes only leading strand DNA synthesis, but few genes crucial for DNA synthesis have been tested genetically for their functions in meiosis. Furthermore, lagging strand synthesis has been assumed to be unnecessary. Here we show that the Arabidopsis thaliana DNA REPLICATION FACTOR C1 (RFC1) important for lagging strand synthesis is necessary for fertility, meiotic bivalent formation, and homolog segregation. Loss of meiotic RFC1 function caused abnormal meiotic chromosome association and other cytological defects; genetic analyses with other meiotic mutations indicate that RFC1 acts in the MSH4-dependent interference-sensitive pathway for CO formation. In a rfc1 mutant, residual pollen viability is MUS81-dependent and COs exhibit essentially no interference, indicating that these COs form via the MUS81-dependent interference-insensitive pathway. We hypothesize that lagging strand DNA synthesis is important for the formation of double Holliday junctions, but not alternative recombination intermediates. That RFC1 is found in divergent eukaryotes suggests a previously unrecognized and highly conserved role for DNA synthesis in discriminating between recombination pathways
