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Ribosomal protein L10a (RpL10A) has been previously established as a stimulator during the early stages of ovarian development in both the banana prawn and the fruit fly. In order to develop a greater understanding of the role of this protein in vertebrates, the present study aimed to characterize the expression profile of rpl10a during gonadal development in fish. It was determined that the expression of rpl10a within genital ridges increased during embryonic development. Although rpl10a expression was observed in both gonadal somatic cells and primordial germ cells, higher levels of both transcript and protein expression were detected in somatic cells. rpl10a transcripts were observed in all of the adult tissues examined. Cellular level expression of rpl10a was subsequently characterized across various maturational stages using in situ hybridization and immunohistochemistry of both testes and ovaries. Analysis of tissue derived from the testis showed high levels of rpl10a expression within spermatogonia and the Sertoli cells attached to them. In ovarian tissue, rpl10a was strongly expressed in chromatin-nucleolus-stage and peri-nucleolus-stage oocytes. The relationship between rpl10a expression and regulation of gonadal development was confirmed using real-time PCR, which was performed in order to analyze rpl10a expression in testicular and ovarian tissues subsequent to incubation with salmon pituitary extract and various sex steroids for 24 h. Among them, 11-ketotestosterone at 100 ng/mL effectively up-regulated expression of rpl10a in testicular tissues, while 17β-estradiol down-regulated rpl10a expression in ovarian tissues. These results suggested that rpl10a played a role in the regulation of gonadal development in fish.

The quality and quantity of DNA are crucial aspects for fish studies based on molecular techniques. The extraction method of genomic DNA is depended on tissue types and organism species. This research aimed to identify an appropriate extraction method for gDNA from the fin of three popular mackerel species in Thailand; short-bodied mackerel (Rastrelliger brachysoma), island mackerel (R. faughni) and Indian mackerel (R. kanagurta). Four different methods for gDNA extraction were compared based on time, quality and quantity of extractable gDNA for PCR technique. Method III showed the highest quantity of gDNA in R. brachysoma and R. kanagurta. Nevertheless, the highest purity of gDNA for both species was obtained by method II and IV, respectively. The gDNA from method IV was successful to amplify the intense band of β-actin fragment. The highest concentration and purity of gDNA from R. faughni were received using method II. However, β-actin gene fragment amplified from gDNA of method IV showed intense bands. These results indicated that method IV was suitable for gDNA extraction from the fin of three mackerel species because of the fastest, high quality and quantity for PCR amplification.