Project description:Seven early developmental stages in channel catfish, Ictalurus punctatus, were selected for transcriptome sequencing and analysis, Differential expression analysis and WGCNA approach was applied. The genes that play vital roles in embryogenesis and regulation of early development in channel catfish were detected. Our work reveals new insights for exploring the underlying mechanisms of channel catfish early development.
Project description:The hybrid between female channel catfish (Ictalurus punctatus) and male blue catfish (Ictalurus furcatus) is superior in feed conversion, disease resistance, carcass yield, and harvestability compared to both parental species. However, heterosis and heterobeltiosis only occur in pond culture, and channel catfish grow much faster than the other genetic types in small culture units. This environment-dependent heterosis is intriguing, but the underlying genetic mechanisms are not well understood. In this study, phenotypic characterization and transcriptomic analyses were performed in the channel catfish, blue catfish, and their reciprocal F1s reared in tanks. The results showed that the channel catfish is superior in growth-related morphometrics, presumably due to significantly lower innate immune function, as investigated by reduced lysozyme activity and alternative complement activity. RNA-seq analysis revealed that genes involved in fatty acid metabolism/transport are significantly upregulated in channel catfish compared to blue catfish and hybrids, which also contributes to the growth phenotype. Interestingly, hybrids have a 40-80% elevation in blood glucose than the parental species, which can be explained by a phenomenon called transgressive expression (overexpression/underexpression in F1s than the parental species). A total of 1,140 transgressive genes were identified in F1 hybrids, indicating that 8.5% of the transcriptome displayed transgressive expression. Transgressive genes upregulated in F1s are enriched for glycan degradation function, directly related to the increase in blood glucose level. This study is the first to explore molecular mechanisms of environment-dependent hetero-sis/heterobeltiosis in a vertebrate species and sheds light on the regulation and evolution of heterosis vs. hybrid incompatibility.
Project description:Clonal channel catfish lymphoid cell lines and mixed lymphocyte cultures (MLC) have proven extremely useful in examining immune responses at the cellular and molecular levels. To date catfish cell cultures have been biologically and phenotypically characterized using a variety of techniques including reverse transcription PCR (RT-PCR), as well as Northern and Southern Blotting. To expand the molecular characterization of these cultures, microarray analysis was employed. Clonal B (3B11), macrophage (42TA), and cytotoxic T cell (TS32.15 and TS32.17) lines and MLC were examined using a cDNA array containing ~ 2500 probes derived from EST libraries prepared from the 42TA macrophage cell line, a MLC, and 5 - 14 day old catfish fry. Analysis showed that each cell line displayed a unique RNA expression profile that included a variety of immune-related genes. Pearson correlation analysis indicated that one cytotoxic T cell line clustered with MLC, whereas a second cytotoxic T cell line was more closely associated with B cells and macrophages
