Infertility Associated with Meiotic Failure in the <i>tremor</i> Rat (<i>tm/tm</i>) is Caused by the Deletion of <i>Spermatogenesis Associated 22</i>
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The <i>tremor</i> rat is an autosomal recessive mutant exhibiting sterility with gonadal hypoplasia in both sexes. The causative mutation <i>tremor</i> (<i>tm</i>) is known as a genomic deletion spanning >200 kb in Chr 10q24. <i>Spermatogenesis associated 22</i> (<i>Spata22</i>) has been shown to be a vertebrate-specific gene essential for the progression of meiosis through prophase I and completion of chromosome synapsis and meiotic recombination using a mouse <i>repro42</i> mutant carrying an <i>N</i>-ethyl-<i>N</i>-nitrosourea (ENU)-induced nonsense mutation in <i>Spata22</i>. In this study, we show that <i>Spata22</i> was identified as the gene responsible for the failure of gametogenesis to progress beyond meiosis I in <i>tm</i> homozygous rats by a transgenic rescue experiment. Meiosis was arrested during prophase I in the mutant testis. Precise mapping of the breakage point revealed that the deleted genomic region spanned approximately 240 kb and comprised at least 13 genes, including <i>Spata22</i>. Rat <i>Spata22</i> was predominantly expressed in the testis, and its transcription increased with the first wave of spermatogenesis, as seen in the mouse ortholog. These results suggest that <i>Spata22</i> may play an important role in meiotic prophase I in rats, as seen in mice, and that the <i>tm</i> homozygous rat may be useful for investigating the physiological function of <i>Spata22</i>, as an experimental system for clarifying the effect of a null mutation, and may be an animal model for studying the pathogenesis and treatment of infertility caused by impaired meiosis.
- Experimental Animals
Experimental Animals 62(3), 219-227, 2013
Japanese Association for Laboratory Animal Science