DIMORPHIC EXPRESSION OF TRANSCRIPTION FACTOR AND STEROIDOGENIC ENZYME GENES DURING GONADAL DEVELOPMENT IN THE INDIAN SPINY LOACH, Lepidocephalus thermalis

Loading...
Thumbnail Image
Date
2017
Journal Title
Journal ISSN
Volume Title
Publisher
Fisheries College and Research Institute, Thoothukudi, Tamil Nadu Dr. J. Jayalalithaa Fisheries University
Abstract
In teleost, the gonads are the primary organs to show sexual dimorphism. The existence of two different forms of a species especially in same population or the difference in morphology between male and female members of same species refers to dimorphism. This differential expression of gene is known as dimorphic expression. Lepidocephalus thermalis also known as spotted loach or common spiny loach is a fresh water fish restricted to India and Srilanka. In the current study, the expression of 14 different transcription factors involved in sex differentiation in Indian spiny loach Lepidocephalus thermalis during different developmental stages was analyzed using real time PCR. Histology sectioning helped to differentiate both male and female gonadal structure of loaches. Oocytes, granulosa, primary follicle were present in female gonad section and spermatids, spermatogonia, spermatocytes were observed in male gonads. Total RNA was isolated from gonads of different age groups of loach by using TRI-reagent method and their concentration and purity was analysed with the help of Nanodrop spectrophotometer at 260 nanometer. cDNA extraction is done from the isolated RNA and the expression profile of these genes are compared to other fishes. Using SYBR Green real-time quantitative PCR was done to amplify the cDNA. Higher expression of sf1 was observed in MSG complex and immature testis, while mature testis showed higher expression of dmrt1. In immature ovary corresponding to 40-80 dph fishes, high expression of dmrt1, sox3, wnt4, sox9a, sf1 and vasa were observed. While in the mature ovary, expression of wt1, pax2, wnt4, sox9b and StAR were found to be high. Our study is the first of this kind revealing the expression patterns of several sex related genes in loach. Our findings may provide valuable information to understand sex difference and gonadal development in loaches. Expression of dmrt1 was found to be low in MSG and it remained low in two different stages of testis analyzed in this study. In contrast, the level to expression of dmrt1 was high in ovary in both stages. Incidentally, dmrt1 expression is testis-specific in many other teleost. It remains to be seen whether any domain-like gene is found in female loach and such has been proposed in few teleost. This has to be analyzed further.
Description
Keywords
null
Citation
Collections