Project description:Cryopreservation of blue catfish sperm can cause variable embryo hatch rates, which is the limiting factor for hybrid catfish breeding. In this study, we investigated gene expression changes caused by cryopreservation using transcriptome profiles of fresh sperm samples and cryopreserved sperm from the same set of blue catfish.
Project description:Channel catfish and blue catfish represent two economically important freshwater aquaculture species in the United States. Our study aims to investigate the gene expression differences between these two catfish species by high-throughput RNA sequencing to understand their associated phenotypic differences in growth and disease resistant. Our transcriptomic analyses provide some insights into gene function differences between the two species and the molecular basis of channel catfish growth advantage in the tank culture environment.
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:This study examined differentially expressed (DE) gene transcripts and regulated pathways of two geographically distinct channel catfish (Ictalurus punctatus) strains and one hybrid catfish (I. punctatus x [blue catfish] I. furcatus) strain to test whether one particular catfish type handled thermal stress better. Following a six-week growth experiment, where fish were subjected to daily cycling temperatures of either 27-31M-BM-0C or 32-36M-BM-0C, mimicking pond fluctuations. We sequenced 18 cDNA libraries of liver samples to obtain 61 million reads per library. There were 5,443 DE transcripts and 41,689 regulated pathways. Northern channel catfish had the highest amount of DE transcripts (48.6%), 5 times that of southern channel catfish, and the greatest amount of transcripts with fold changes M-bM-^IM-% 2. The overall amount of temperature-induced DE transcripts between southern hybrid and southern channel catfish was fairly comparable in relation to that of northern channel catfish, however, there were more transcripts up- or downregulated with M-bM-^IM-% 2 fold changes in channel catfish strains compared to the southern hybrid catfish. Results from this study strongly suggest genetic differences between geographic catfish types affect physiological responses to thermal stress. Furthermore, a number of genes were linked to thermal stress tolerance, which may be beneficial for understanding geographic differences in thermal stress tolerance in ectotherms and for strain development of catfish. Hepatic mRNA profiles of three fingerling catfish types following a six week growth experiment of daily cycling temperatures of either 27-31M-BM-0C or 32-36M-BM-0C, mimicking pond fluctuations.
Project description:We have utilized a high-density oligonucleotide microarray for catfish in order to study the transcriptomic responses of blue catfish following infection with E. ictaluri and to identify and develop important immune-related markers for future characterization and genetic mapping. Microarray analysis of the transcriptome profile of the blue catfish liver following infection with the Gram negative bacterium led to the identification of 103 differentially expressed transcripts. Results indicated the strong upregulation of several pathways likely involved in the inflammatory immune response. A multifaceted response to infection was observed, encompassing the complement cascade, iron regulation, inflammatory cell signaling, and antigen processing and presentation. The induction of several components of the MHC class I-related pathway following infection with an intracellular bacterium is reported here for the first time in fish. Taken together, the microarray results add to our understanding of the teleost immune responses and will provide a solid foundation for future functional characterization, genetic mapping, and QTL analysis of immunity-related genes from catfish. Keywords: Disease state analysis