The interneship will take place in the Institute of Marine Sciences of Andalucía in Puerto Realn Cádiz. The objectives of our group are focused on determining the function of several factors in the regulation of the initial stages of male and female gametogenesis in fish, using the European sea bass as model. In fish culture still exist some important problems related to reproduction to be solved. One of these problems is precocious maturation when fish become sexually active before time of puberty, diverting energy to reproduction and reducing somatic growth. In aquaculture, also a high number of breeders has to be maintained in order to get enough quantity of eggs to obtain an optimal production of fish. The knowledge of the control of the first stages of gametogenesis is a key factor to face and try to solve these problems. In the first stages of gametogenesis is when fecundity is determined, and also controlling factors regulating these stages, precocious maturation could be avoid. Therefore, the final aim of the study is to develop hormonal therapies to stimulate or inhibit the reproductive cycle in order to improve egg production increasing fecundity or produce sterile fish to avoid precocious maturation according to the needs of the fish farmers. Potential factors involved in the control of early stages of gametogenesis are kit ligand (also known as stem cell factor), Gndf (glial cell line-derived neurotrophic factor) and some members of the TGF-beta (transforming growth factor beta) superfamily, Gdf9, Bmp15 and Bmp4. All these ligands interact with specific receptors to provoke changes in their target cells. The nucleotide sequences of these factors and receptors are already available for the European sea bass. Within this study, the student(s) will participate in one or different aspects of this research, including production of recombinant proteins of these factors in yeast, analysis of protein expression of these factors in ovary and testis during the reproductive cycle, and localization of their mRNA and protein by in situ hybridization and immunochemistry. Students will gain skills in techniques for working with nucleic acids and proteins such as PCR, electrophoresis, Western Blot, chromatography, and the use of databases and bioinformatic tools for gene and protein sequence analysis.