THE MOUSE RECA-LIKE GENE DMC1 IS REQUIRED FOR HOMOLOGOUS CHROMOSOME SYNAPSIS DURING MEIOSIS

The mouse Dmc1 gene is an E. coli RecA homolog that is specifically ex pressed in meiosis. The DMC1 protein was detected in leptotene-to-zygo tene spermatocytes, when homolog pairing likely initiates. Targeted ge ne disruption in the male mouse showed an arrest of meiosis of germ ce lls at the early zygotene stage, followed by apoptosis. In female mice lacking the Dmc1 gene, normal differentiation of oogenesis was aborte d in embryos, and germ cells disappeared in the adult ovary. Meiotic c hromosome analysis of Dmc1-deficient mouse spermatocytes revealed rand om spread of univalent axial elements without correct pairing between homologs. In rare cases, however, we observed complex pairing among no nhomologs. Thus, the mouse Dmc1 gene is required for homologous synaps is of chromosomes in meiosis.