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: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:Channel catfish, Ictalurus punctatus, is an important model U.S. aquaculutre species. Given its role in food production, the catfish immune response to industry-relevant pathogens has been extensively studied and has provided crucial information on innate and adaptive immune function during disease progression. To further examine the channel catfish immune system, single-nuclei RNA sequencing on whole spleens from three adult individuals was performed. Spleen cell suspensions were prepared by passing tissues through cell sieves. Single-cell RNAseq libraries were then prepared using the 10X Genomics Chromium X with the Next GEM Single Cell 3’ Reagents and sequenced 2x150bp on an Illumina sequencer. Each demultiplexed library was aligned to the CoCo_2.0 channel catfish reference assembly, filtered, and counted to generate feature-barcode matrices. Cluster analysis allowed for the identification of multiple cell types including erythrocytes, hematopoietic stem cells, B cells, T/NK cells, myeloid lineage derivatives, plasma cells and endothelial cells. The majority of cells detected were erythrocytes, which are nucleated in teleost fish.
Project description:Bacterial 16S rRNA V4 amplicons representing intestinal microbiota of channel catfish across developmental ontogeny (3, 65, 125, 193 dph), dietary changes (FM control and three alternative formulations), and/or host-genetics (three strains of blue and channel catfish). Raw sequence reads