Expression of Protamine mRNA in Relation to Spermatogenic Activity in Japanese Quail

Abstract

This study was conducted to elucidate relationship between testicular protamine mRNA expression and spermatogenic activity in the quail as the following experiments. (1) Quail were raised under continuous light condition after hatching and body weights, testis weights, spermatogenic activity and protamine mRNA levels were determined weekly between 3 and 8 weeks. (2) The other group of quail raised under continuous light condition up to 6 weeks after hatching were kept in either continuous light or reduced light-length (8-hour light, 16-hour darkness) conditions for 3 weeks. At 6 and 9 weeks old, the same parameters were measured as in the foregoing experiment. Spermatogenic activity was evaluated by Bartholomew’s classification after histological examination of the testis and mRNA expression of testis protamine was analyzed by Northern blot. Between 3 and 5 weeks old, body weights, testis weights, and cloacal gland protrusion areas significantly increased and thereafter they stayed at plateau levels. Spermatogenic activity markedly increased from stage II to VI between 3 and 5 weeks old and stayed at stage VI up to 8 weeks old. Spermatids and immature sperm were firstly observed at 4 weeks old. Protamine mRNA levels were also first detected at 4 weeks old and increased at 5 weeks old. A marked expression were maintained after 6 weeks old. In contrast, short daylengths treatment after 6 weeks old significantly reduced testis weights, cloacal gland protrusion areas, spermatogenic activity, and protamine mRNA levels at 9 weeks old (P<0.05) when compared to those raised under continuous light condition. Spermatogenic activity dropped from the full activity of stage VI to elongated spermatid (IV) or spermatocyte (II-III) stage after the treatment. Protamine mRNA levels also significantly decreased in response to short daylengths. These results suggest that protamine mRNA expression is highly related to spermatogenic activity in the quail.

Keywords

• protamine mrna
• spermatogenesis
• quail
• short day treatment
• testis