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The mouse RecA-like gene Dmc1 is required for homologous chromosome synapsis during meiosis
Abstract:
The mouse Dmc1 gene is an E. coli RecA homolog that is specifically expressed in meiosis. The DMC1 protein was detected in leptotene-to-zygotene spermatocytes, when homolog pairing likely initiates. Targeted gene disruption in the male mouse showed an arrest of meiosis of germ cells at the early zygotene stage, followed by apoptosis. In female mice lacking the Dmc1 gene, normal differentiation of oogenesis was aborted in embryos, and germ cells disappeared in the adult ovary. Meiotic chromosome analysis of Dmc1-deficient mouse spermatocytes revealed random spread of univalent axial elements without correct pairing between homologs. In rare cases, however, we observed complex pairing among nonhomologs. Thus, the mouse Dmc1 gene is required for homologous synapsis of chromosomes in meiosis.
Insights
The mouse Dmc1 gene is essential for homologous chromosome pairing during meiosis. Its absence causes meiotic arrest, germ cell loss, and failed synapsis in both male and female mice.
Area of Science:
- Genetics
- Molecular Biology
- Reproductive Biology
Background:
- The Dmc1 gene in mice is a homolog of E. coli RecA.
- It is specifically expressed during the meiotic process.
Purpose of the Study:
- To investigate the role of the mouse Dmc1 gene in meiosis.
- To understand its function in homologous chromosome synapsis.
Main Methods:
- Targeted gene disruption of the Dmc1 gene in male and female mice.
- Analysis of meiotic progression and germ cell development.
- Meiotic chromosome analysis in Dmc1-deficient spermatocytes.
Main Results:
- Dmc1 deficiency caused meiotic arrest at the zygotene stage and germ cell apoptosis in males.
- Oogenesis was aborted, and germ cells were lost in adult ovaries of female mice lacking Dmc1.
- Chromosome analysis revealed random axial element spread and failed homologous pairing in Dmc1-deficient spermatocytes.
Conclusions:
- The mouse Dmc1 gene is indispensable for homologous synapsis during male and female meiosis.
- Dmc1 plays a critical role in ensuring accurate chromosome pairing for successful gametogenesis.