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:Channel catfish, Ictalurus punctatus, are the primary cultured species of the catfish industry. Significant losses in production are attributed to bacterial diseases which are challenging to control and new interventions need to be developed. To gain insight into the in situ catfish immune system, we used single-nuclei RNAseq. We produced two single-nuclei atlases from three individual catfish using flow cytometry sorted IgM+ splenic cells. Libraries were prepared using the 10X Genomics system and sequenced on an Illumina sequencer. The reads were aligned to the reference genome (Ip Coco_2.0) using Cell Ranger (v8.0.0).
Project description:Channel catfish (Ictalurus punctatus) and tra catfish (Pangasianodon hypophthalmus) both belong to the order Siluriformes. Channel catfish does not possess an air-breathing organ (ABO), and thus cannot breathe in the air, while tra catfish is a facultative air-breather and use the swim bladder as its air-breathing organ, which provides for aerial breathing in low oxygen conditions. Tra and channel catfish serve as a great comparative model for studying the transition of life from water to terrestrial living, as well as for understanding genes that are crucial for development of the swim bladder and the function of air-breathing in tra catfish. We selected seven developmental stages in tra catfish for RNA-Seq analysis based on their transition to a stage that could live at 0 ppm oxygen. More than 587 million sequencing clean reads were generated in tra catfish, and a total of 21, 448 unique genes were detected. A comparative genomic analysis was conducted between channel catfish and tra catfish. Gene expression analysis was performed for these tra catfish specific genes. Hypoxia challenge and microtomy experiments collectively suggested that there are critical timepoints for the development of the air-breathing function and swim bladder development stages in tra catfish. Key genes were identified to be the best candidates of genes related to the air-breathing ability in tra catfish. This study provides a large data resource for functional genomic studies in air-breathing function in tra catfish, and sheds light on the adaption of aquatic organisms to the terrestrial environment.
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:Catfish farming is the largest aquaculture industry in the U.S., where hybrid catfish produced by channel catfish, Ictalurus punctatus ♀ × blue catfish, I. furcatus ♂, represent >50% of the harvest. Typically, older blue catfish (≥5 years) are selected for artificial fertilization. However, observations at our facilities and reports from hatcheries indicate a high degree of variation in reproductive performance among individuals. Thus, it is essential to establish links between paternal age and reproductive success, as it is apparent that advanced paternal age leads to changes in reproductive performance. Since there are no prior studies regarding the changes in testis transcriptome in blue catfish males during aging, we evaluated global gene expression of testis at age 2,4,7 and 9. Significant differential expressed genes and gene ontology of pairwise comparisons between age 2 and each test age are presented and discussed.
Project description:Catfish is the most important species in US aquaculture, accounting for 70% of freshwater production. The production of hybrids of female channel catfish (Ictalurus punctatus) and male blue catfish (I. furcatus) constitutes over 50% of the total harvest due to their superior production traits and enhanced disease resistance. However, hybrids cannot be produced naturally, and male must be euthanized for sperm collection. An appropriate storage condition is essential to preserve the sperm’s ability to fertilize eggs during the female spawning season. Cryopreservation is a widely used method for sperm storage. However, it has been shown to affect sperm gene expression in many vertebrate species. A high degree of individual variability among cryopreserved sperm was reported, resulting in huge variations in hatch rate. Since high-quality gametes are the prerequisites for hybrid catfish reproduction, in this study, we investigate the molecular mechanisms underlying male reproductive performance, which is critical for the accurate prediction of hatching rate and offspring performance in hatchery environments.
Project description:A high-density oligonucleotide microarray for channel catfish (Ictalurus punctatus) was designed and produced with Maskless Array Synthesizer technology (MAS). The microarray contained ~379,652 24-mer oligonucleotides covering ~18,999 catfish unique sequences. The global expression profiling of the catfish spleens stimulated by lipopolysaccharide (LPS) for 2h, 4h, 8h and 24h was investigated with the microarray. In the spleen samples, 409 genes were identified to be induced or repressed greater than 2-fold by LPS treatment. Self-organizing maps (SOM) clustering analysis was applied to interpret gene expression patterns, and 84 of these genes were clustered into six expression patterns. Real-time RT-PCR was used to verify the microarray results for 9 selected genes representing different expression levels. The results from real-time RT-PCR were positively correlated (R^2 = 0.87) with the results from the microarray. Keywords: time course
Project description:Walking catfish (Clarias macrocephalus) and channel catfish (Ictalurus punctatus) are freshwater fish species of the Siluriformes order. C. macrocephalus has both gills and modified gill structures serving as an air breathing organ (ABO) which allows them aerial breathing (AB), while I. punctatus does not possess an air-breathing organ (ABO), and thus cannot breathe in air. These two species provide an excellent model for studying the molecular basis of accessory air-breathing organ development in teleost fish. In this study, seven development stages in C. macrocephalus were selected for RNA-seq analysis to compare with channel catfish as the time when air breathing organ developed and became functional. Through comparative genetic contents analysis, 1,458 genes were identified to be present in C. macrocephalus, but absent from I. punctatus. Gene expression analysis and protein-protein intersection (PPI) analysis were performed, 26 genes were selected in C. macrocephalus, including mb, ngb, hbae genes, which are mainly associated with oxygen carrier activity, oxygen binding and heme binding activities. Our work provides a large data resource for exploring the genomic basis of air breathing function in C. macrocephalus and offers an insight into the adaption of aquatic organisms to hypoxia and high ammonia environment.