| Abstract | Many species from fruit flies to humans exhibit sexual dimorphism. Much of this phenotypic variation can be attributed to differential expression of genes between males and females, also known as sex-bias gene expression. The salmonid family, which includes salmon, trout, and charr, are known to exhibit a high degree of sexual dimorphism in many phenotypes. However, previous sex-bias gene expression studies have been limited to either gonadal tissues, or whole embryos at early stages of development. This project aims to expand our knowledge of sex-bias gene expression by identifying and quantifying gene expression within the brain tissue of two-year old brook trout (Salvelinius fontinalis). A special emphasis was placed on the sdY gene, a possible master sex-determining gene in salmonids. Expression of sdY has been characterized in the gonads of developing salmonids, but its involvement in processes other than sex determination is unknown. This project looked for similar patterns of expression between sdY and other genes to try and reveal the role of sdY in brain tissue. Using RNA-seq data and qRT-PCR validation, 12 genes were measured for sex-bias gene expression. Of these genes, only sdY showed a significant difference in expression between male and female brook trout (p =< 0.05). Two other genes (sox9, ar-alpha) were upregulated in male brook trout although this difference in expression was not significant (p>0.05). These results indicate that sdY is being expressed in the brains of mature male brook trout far past the point of sex determination and that the upregulation of sdY in males could be connected to androgen receptivity and chondrogenesis pathways. |
