Project description:Commercial production of tilapia relies on monosex cultures of males, which so far proved difficult to maintain in large scale production facilities. Thus, a better understanding of the genetic architecture of the complex trait of sex determination in tilapia is needed.We aimed to detect genes that were differentially expressed by gender at early embryonic development. Artificial fertilization of O. niloticus females with either sex-reversed males (ΔXX) or genetically-modified YY 'supermales' resulted in all-female and all-male embryos, respectively. Pools of all-female and all-male embryos at 2, 5 and 9 days post fertilization were used for custom Agilent eArray. 56 pool samples of Nile tilapia full siblings groups (female or male) at day 2, 5 or 9 post fertilization were subjected to total RNA extraction from whole embryo tissues and hybridized to the custom Agilent array. Each sample was yielded from different cross of artificial fertilization: six dams X five sires. The resulting gender were known based on the sire, sex-reversed males (ΔXX) or genetically-modified YY 'supermales' resulted in all-female and all-male embryos, respectively.
Project description:Cichlids fishes exhibit extensive phenotypic diversification and speciation. In this study we integrate transcriptomic and proteomic signatures from two cichlids species, identify novel open reading frames (nORFs) and perform evolutionary analysis on these nORF regions. We embark comparative transrcriptomics and proteogenomic analysis of two metabolically active tissues, the testes and liver, of two cichlid species Oreochromis niloticus (Nile tilapia, ON) and Pundamilia nyererei (Makobe Island, PN). Our results suggest that the time scale of speciation of the two species can be better explained by the evolutionary divergence of these nORF genomic regions.
Project description:In fish, the sex determining mechanisms can broadly be classified as genotypic (GSD), temperature-dependent (TSD), or genotypic plus temperature effects (GSD+TE). For the fish species with TSD or GSD+TE, extremely high or low temperature can affect its sex determination and differentiation. For long time, the underlying changes in DNA methylation that occur during high or low temperature induced sex reversal have not been fully clarified. In this study, we used Nile tilapia as a model to perform a genome-wide survey of differences in DNA methylation in female and male gonads between control and high temperature induced groups using methylated DNA immunoprecipitation (MeDIP). We identified the high temperature induction-related differentially methylated regions (DMRs), and performed functional enrichment analysis for genes exhibiting DMR. These identified differentially methylated genes were potentially involved in the connection between environmental temperature and sex reversal in Nile tilapia. In this study, four samples (control females, CF; control males, CM; induced females, IF; induced males, IM) were analyzed.
