Males homozygous for this ENU-induced mutation in the Ccdc62 (coiled-coil domain containing 62) gene have disrupted spermiogenesis with failed acrosome formation that results in infertility, but homozygous females and heterozygous males have normal fertility.
Mary Ann Handel, The Jackson Laboratory
The ENU-induced repro29 mutation is a point mutation in the Ccdc62 (coiled-coil domain containing 62) gene that results in the formation truncated protein.
Homozygous males have normal testes size and weight and a normal number of sperm, but are sterile due to deformed sperm. The sperm head is bent and there are outer dense fibers with the head and middle piece enclosed in retained cytoplasm. Almost 100% of sperm are deformed and the number of motile sperm is less than 5% normal. Although a shortened protein of approximately 32 kDa instead of 72 kDa is found in developing spermatids of homozygotes, this truncated protein fails to correctly localize to the developing acrosome, as wild-type protein does, and instead shows a staining pattern of larger cytoplasmic aggregates. Although the morphology of the spermatid nuclei is relatively normal during the Golgi, cap and elongation phases, it becomes condensed in the maturation phase. Heterozygous males and homozygous females have normal fertility and litter size, and homozygous males do mount females resulting in a plug, but fail to impregnate females.
C57BL/6J males were exposed to ENU and subsequently bred to C3HeB/FeJ females. The male offspring were bred to C3HeB/FeJ females and their female offspring were backcrossed to their carrier male father to generate pups that could be homozygous for any ENU-induced mutation. After one further generation of sibling intercrossing sperm was frozen from heterozygous males. Cryo-recovery was done using C57BL/6J oocytes and heterozygous males identified by genotyping were then used for a new sperm freeze. The mutation has been identified as a C to T point mutation that converts an arginine to a stop codon (R284*) in exon 6 of the Ccdc62 (coiled-coil domain containing 62) gene. The repro29 mutation results in the formation of a premature stop codon and truncated protein.
|Allele Name||reproductive mutant 29, JAX Reproductive Mutagenisis Program|
|Allele Type||Chemically induced (ENU) (Not Specified)|
|Gene Symbol and Name||Ccdc62, coiled-coil domain containing 62|
|Strain of Origin||C57BL/6J|
|Molecular Note||ENU mutagenesis created a C>T point mutation in exon 6, changing arginine codon CGA to stop codon TGA (p.Arg284Stop or p.R284*) in the highly conserved second coiled-coil domain. Western blot analysis showed the expression of a truncated peptide from this allele and qRT-PCR showed a significant reduction of mRNA expression from the allele in testes.|
When maintaining a live colony, heterozygous male mice may be bred to homozygous females. Homozygous males are sterile.
When using the reproductive mutant 29, JAX Reproductive Mutagenisis Program mouse strain in a publication, please cite the originating article(s) and include MMRRC stock #43945 in your Materials and Methods section.