Isolation of Aeromonas hydrophila from EUS Affected Shing Heteropneustes fossilis of a Fish Farm in Mymensingh

MiR-217 targets TBK1 to modulate inflammatory response in grass carp following infection with Aeromonas hydrophila

The current study demonstrated that miR-217 modulates inflammation in grass carp (Ctenopharyngodon Idella) infected with Aeromonas hydrophila. Bacterial infection in grass carp causes high levels septicemia, which arises with systemic inflammatory responses. As a result leading to the development of hyperinflammatory state which causes septic shocks and lethality. Based on the current data, TBK1 was confirmed to be the target gene of miR-217 after a successful gene expression profiling or luciferase experiment and miR-217 expression in CIK cells. Furthermore, TargetscanFish6.2 predicted TBK1 as the target gene of miR-217. Quantitative real-time PCR was performed to measure miR-217 expression levels for six immune-related genes and miR-217 regulation in grass carp after A. hydrophila infection in CIK cells. In grass carp CIK cells, the expression of TBK1 mRNA was up-regulated under poly (I: C) stimulation. The transcriptional analysis of the immune-related genes demonstrated that the expression levels of tumor necrosis factor-α (TNF-α), interferon (ifn), interleukin 6 (il-6), interleukin 8 (il-8), and interleukin 12 (il-12) were altered after a successful transfection into the CIK cells, proposing that miRNA regulates immune responses in grass carp. These results provided a theoretical basis and contribute to further studies on the pathogenesis and host defensive system during A. hydrophila infection.

Community Structure and Functional Annotations of the Skin Microbiome in Healthy and Diseased Catfish, Heteropneustes fossilis

The skin mucosa of fish serves as a primary barrier against pathogens. In lesion sites in diseased fish, the mucosal barrier is expected to be compromised, with a substantial presence of potential pathogens. An understanding of the skin microbiome and its functional repertoire would provide important insights into host-microbe interactions, which has important implications for prophylactic measures in aquaculture. This study revealed the skin microbiomes and their functional annotations from healthy and diseased stinging catfish (Heteropneustes fossilis) based on 16S rRNA metagenomics. The OTUs consisted of four major phyla, Proteobacteria, Bacteroidota, Actinobacteriota and Firmicutes. Among members of the predominant phyla, Proteobacteria were rich in healthy fishes, but Bacteroidota and Firmicutes were significantly differentiated in healthy and diseased fish. The diversified microbiome was high in the skin of healthy fishes and did not significantly differ from that of the diseased groups. At the genus level, Pseudomonas showed the highest abundance in healthy fish but was nearly absent in diseased fish, whereas Flavobacterium showed the highest abundance in diseased fish. Linear discriminant analysis identified two phyla (Bacteroidota, Firmicutes) and two genera (Flavobacterium, Allorhizobium) that were consistently identified in diseased fishes. Functional prediction analysis specified that the genes related to physiological functions such as metabolism, immune and digestive systems and environmental adaptations could be highly expressed in diseased fishes. The present study indicates that the compositions, richness and functions of the bacterial community could influence the health status of cultured stinging catfish. Aquaculture-associated pathogenic bacteria may be identified, and preventive measures can be taken for the surveillance of fish health.

Bentonite clay supplemented diet on immunity in stinging catfish, Heteropneustes fossilis against Aeromonas hydrophila

The effect of Sodium Bentonite (SB) enriched diet on growth performance, innate immune response, and disease resistance in stinging catfish, Heteropneustes fossilis against Aeromonas hydrophila is reported. The infected fish fed with 5% SB had the maximum weight gain diet (PWG %) and specific growth rate (SGR %) were 26% and 29% when compared to 14% and 17% with 10% diet. Similarly the phagocytic activity increased significantly when infected fish were fed with 5% or 10% SB diets during the experimental period; the complement, respiratory burst and lysozyme activities were also significantly enhanced on weeks 2 and 4. The lower cumulative mortality (10% and 15%) was observed when the infected fish were fed with 5% and 10% SB diets for 30 days. The results suggest that the infected H. fossilis after administration of 5% and 10% SB enriched diets for 30 days had significantly improved growth performance, innate immunity, and disease resistance against A. hydrophilla. Hence, sodium bentonite can be used as a feed additive to stimulate immunity and for disease resistance in the effective production of economically valuable freshwater catfish, H. fossilis.