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| Expression and Cellular Localization of Dazl Gene in Testis of Sheep (Ovis aries) at Different Developmental Stages |
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Abstract Deleted in azoospermia-like gene (Dazl) is required for differentiation of male animal germ cells. However, the regulation mechanisms of Dazl gene are not exactly the same in broad variety of animals or in the same animal at different developmental stages. In order to investigate the expression patterns, cellular localization and regulatory mechanisms involving with spermatogenesis of the Dazl gene in sheep (Ovis aries)testes at different developmental stages, testis, heart, liver, spleen, lung, kidney and muscle tissues were collected from Small-tail Han sheep at 0, 2, 5, 12 and 24 months of age. The Dazl mRNA expression patterns in 0, 2, 5, 12, 24-month-old sheep testes and multiple somatic tissues, including heart, liver, spleen, lung, kidney and muscle of 12-month-old sheep were detected by quantitative real time PCR (qRT-PCR), and the Dazl protein expression and cellular localization in testes at different developmental stages were observed and measured by Western blot and immunohistochemistry, respectively. The qRT-PCR and western blot results revealed that Dazl genes were expressed in sheep testes throughout development at mRNA and protein levels, and their expression patterns were similar basically. The Dazl mRNA and protein were at a lower expression level in pre-pubertal sheep testes (0-, 2- and 5-month-old), and the expression of the Dazl mRNA and protein in 12-month-old were significantly higher than those in 0-, 2- and 5-month-old (P＜0.01), whereas their expression levels were decreased in 24-month-old sheep testis. The qRT-PCR results in various tissues at 12 months of age, including testis, heart, liver, spleen, lung, kidney and muscle tissues, showed that the Dazl mRNA was predominantly expressed in testis, and low-expressed in heart, whereas not expressed in other tissues. The immunohistochemical staining in testes at different developmental stages showed that the Dazl protein was localized to Leydig cells in pre-pubertal (0-,2 -and 5-month-old) sheep testes, while it was localized to Leydig cells, primary spermatocytes, secondary spermatocytes and sperm cells in 12- and 24-month-old sheep testes. These results suggested that the Dazl gene was highly expressed in testes, playing vital roles in the proliferation of Leydig cells in various age of sheep testes, spermatocytes and sperm cells in post-pubertal sheep testes. It is inferred that the Dazl gene is involved in the regulation of postnatal ovine spermatogenesis via direct effect (modulating the maturation and meiosis of spermatocytes) and indirect effect (modulating the proliferation of Leydig cells). The observation provides a scientific basis and reference for further research on the regulatory mechanism of Dazl gene during spermatogenesis.
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Received: 13 July 2017
Published: 14 February 2018
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