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:Guava Psidium guajava L (Pg) and bhumi amla Phyllanthus amarus Schum. et Thonn (Pa) are well-known plants in traditional medicine. However, the capacity of these plants for improving the immune system of aquatic species has received less attention so far. This study aimed to investigate the effects of single supply or mixture of Pg and Pa extracts on immune responses, disease resistance and liver proteome profiles in striped catfish Pangasianodon hypophthalmus. Fish were fed diets including basal diet 0% or one of three doses of each plant extract, either alone or in mixture, 0.08, 0.2 or 0.5% Pg, Pa or mixture (Pg:Pa, v/v) for 6 weeks. The immune parameters (respiratory burst activity (RBA); nitric oxide synthase (NOS), total immunoglobulin, lysozyme and complement activities) were examined at W3, W6 post-feeding, and after challenge test. The growth parameters and the challenge test with Edwardsiella ictaluri were done at W6. The liver proteome profiles were analysed in W6 at 0.08% and 0.5% of each extract. The results showed that extract-based diets significantly improved growth parameters in the Pg0.2 group compared to control. The cellular immune responses in spleen and the humoral immune responses in plasma were significantly improved in a dose and time-dependent manner. Diets supplemented with single Pg and Pa extracts, and to lesser extent to combined extracts, could significantly decrease the mortality of striped catfish following bacterial infection compared to control. The proteomic results indicated that some pathways related to immune responses, antioxidant and lipid metabolism were enriched in liver at W6. Several proteins (i.e., CD8B, HSP90AA1, HSP90AB1, PDIA3, CASP8, TUBA1C, CCKAR, GNAS, GRIN2D, PLCG1, PRKCA, SLC25A5, VDAC2, ACTN4, GNAI2, LCK, CARD9, NLRP12, and NLRP3) were synergistically upregulated in mixture of Pg and Pa-based diets compared to control and single dietary treatments. Taken together, the results revealed that single Pg and Pa extracts at 0.2 and 0.5% and their mixture at 0.08 and 0.5% have the potential to modulate the immune mechanisms and disease resistance of striped catfish. Moreover, the combination of Pg and Pa in diets suggested positive synergistic effects liver proteome profile related to immune system processes.