Double-stranded DNA breaks and gene functions in recombination and meiosis

Meiotic prophase Ⅰ is a long and complex phase.Homologous recombination is an important process that occursbetween homologous chromosomes during meiotic prophase Ⅰ.Formation of chiasmata,which hold homologous chro-mosomes together until the metaphase Ⅰ to anaphase Ⅰ transition,is critical for proper chromosome segregation.Recentstudies have suggested that the SPO 11 proteins have conserved functions in a number of organisms in generating sites ofdouble-stranded DNA breaks (DSBs) that are thought to be the starting points of homologous recombination.Processingof these sites of DSBs requires the function of RecA homologs,such as RAD51,DMC 1,and others,as suggested bymutant studies;thus the.failure to repair these meiotic DSBs results in abnormal chromosomal alternations,leading todisrupted meiosis.Recent discoveries on the functions of these RecA homologs have improved the understanding of themechanisms underlying meiotic homologous recombination.