Project description:Impact of feed additives on surface mucosal health and columnaris susceptibility in channel catfish fingerlings (ictalurus punctatus)
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: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 mucosal surfaces of fish serve as the first-line of defense against the myriad of aquatic pathogens present in the aquatic environment. The immune repertoire functioning at these interfaces is still poorly understood. The skin, in particular, must process signals from several fronts, sensing and integrating environmental, nutritional, social, and health cues. Pathogen invasion can disrupt this delicate homeostasis with profound impacts on signaling throughout the organism. Here, we investigated the transcriptional effects of virulent A. hydrophila infection in channel catfish skin, Ictalurus punctatus. We utilized an 8X60K Agilent microarray to examine gene expression profiles at critical early timepoints following challenge—2 h, 8 h, and 12 h. Expression of a total of 2,168 unique genes was significantly perturbed during at least one timepoint. We observed dysregulation of a number of genes involved in antioxidant, cytoskeletal, immune, junctional, and nervous system pathways. In particular, A. hydrophila infection rapidly altered a number potentially critical lectins, chemokines, interleukins, and other mucosal factors in a manner predicted to enhance its ability to adhere and invade the catfish host.
Project description:Fish skin is a critical regulatory organ, serving not only as a physical barrier to pathogen entry, but also as a sophisticated integrator of aquatic environmental, social and nutritional cues through roles in immunity, osmoregulation, and endocrine signaling. Integral to the complexity of teleost skin is the mucus layer secreted by epidermal goblet cells. Pathogen invasion can disrupt this delicate homeostasis with profound impacts on signaling throughout the organism. Here, we investigated the transcriptional effects of virulent A. hydrophila infection in blue catfish skin, Ictalurus furcatus. We utilized an 8X60K Agilent microarray to examine gene expression profiles at critical early timepoints following challenge—2 h, 12 h, and 24 h. Expression of a total of 1,155 unique genes was significantly perturbed during at least one timepoint. We observed dysregulation of a number of genes involved in including antioxidant/apoptosis, cytoskeletal rearrangement, immune response, junctional/adhesion, and proteases. In particular, A. hydrophila infection rapidly altered a number potentially critical lectins, chemokines, interleukins, and other mucosal factors in a manner predicted to enhance its ability to adhere and invade the catfish host. Two-condition experiment, control vs. infected skin. Biological replicates: 3 control replicates, 3 infected replicates.3 timepoints
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: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 27-31°C or 32-36°C, 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 ≥ 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 ≥ 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.