Research Projects

The model organism Clarias magur (also known as C. batrachus) belongs to a diverse group of ray-finned catfish (order siluriformes) that are mostly benthic freshwater fishes (Ng and Kottelat, 2008; 2013; Kushwaha et al., 2021). Catfishes (annual spawners) undergo a seasonal reproductive cycle which is controlled by a the actions of gonadotropin-releasing hormone, growth hormone, follicular stimulating hormone, luteinizing hormone and sex steroid hormones (Goos et al., 1999; Trudeau et al., 2000). Additionally, catfishes can reverse their sex according to various environmental/social/hormonal cues during early development. Concepts and mechanisms involving sexual plasticity and gametogenesis in fishes including catfish has been covered extensively in the book, "sexual Plasticity and Gametogenesis in Fishes" by PI, senthilkumaran (2013) and co-authors. However, distinct information about gonadal transdifferentiation in sex-changing fishes still remains limited. Furthermore, functional feminization could be achieved through estrogen diet in channel catfish. On the contrary, potential androgens produced female dominant populations suggesting that hormone treatment could not regulate male sex development in catfishes (Davis et al., 1990, 1992). Additionally, MT treatment resulted in intersex in catfish wherein distinction between male and female gonad was possible from 50 dph onwards morphologically (Raghuveer and senthilkumaran, 2009). some of the above mentioned studies have been conducted in PI's laboratory, yet details on gonadal transdifferentiation are highly limited. Fishes are excellent animal models to study transdifferentiation during the process of sex reversal as they can change sex in both directions at different time points among vertebrates. Till date studies on gonadal transdifferentiation have not been studied in Indian habitat food fishes. Hence, studies on this line are absolutely essential to get new information on gonadal transdifferentiation and sex reversal. To execute the project, following research objectives will be implemented. (i) Identification of genes/factors during sex steroid-induced gonadal transdifferentiation in catfish after suitable experimentation for sex reversal followed by transcriptome analysis. (ii) Tissue distribution and localization of identified genes/factors involved in gonadal transdifferentiation for molecular characterization using in situ hybridization and immunohistochemical analysis. (iii) Transient gene silencing of the putative factors to identify their functional role with reference to induced sex reversal.