Establishment and identification of the head kidney cell line of yellowfin seabream (Acanthopagrus latus) and its application in a virus susceptibility study.

The yellowfin seabream (Acanthopagrus latus) is a crucial marine resource owing to its economic significance. Acanthopagrus latus aquaculture faces numerous challenges from viral diseases, but a robust in-vitro research model to understand and address these threats is lacking. Therefore, we developed a novel A. latus cell line from head kidney cells called ALHK1. This study details the development, characterisation, and viral susceptibility properties of ALHK cells. This cell line primarily comprises fibroblast-like cells and has robust proliferative capacity when cultured at 28 °C in Leibovitz's L-15 medium supplemented with 10-20% foetal bovine serum. It exhibited remarkable stability after more than 60 consecutive passages and validation through cryopreservation techniques. The specificity of the ALHK cell line's origin from A. latus was confirmed via polymerase chain reaction (PCR) amplification of the cytochrome B gene, and a chromosomal karyotype analysis revealed a diploid count of 48 (2n = 48). Furthermore, the lipofection-mediated transfection efficiency using the pEGFP-N3 plasmid was high, at nearly 40%, suggesting that ALHK cells could be used for studies involving exogenous gene manipulation. In addition, ALHK cells displayed heightened sensitivity to the large mouth bass virus (LMBV), substantiated through observations of cytopathic effects, quantitative real-time PCR, and viral titration assays. Finally, the response of ALHK cells to LMBV infection resulted in differentially expressed antiviral genes associated with innate immunity. In conclusion, the ALHK cell line is a dependable in-vitro platform for elucidating the mechanisms of viral diseases in yellowfin seabream. Moreover, this cell line could be valuable for immunology, vaccine development, and host-pathogen interaction studies.

Characteristics of microplastic pollution in golden pompano (Trachinotus ovatus) aquaculture areas and the relationship between colonized-microbiota on microplastics and intestinal microflora.

Microplastic (MPs) pollution is a global marine environmental problem. The effects of MPs on the gut microbiota of aquatic organisms have received considerable attention. For example, microbes colonizing MPs in pond cultures alter the structure and function of the intestinal microbes of shrimp and fish. It was hypothesized that bacteria on MPs in natural mariculture areas also interact with the intestinal flora of golden pompano (Trachinotus ovatus) because biofilms can form on the surface of MPs during long-term floating in seawater. To our knowledge, this study is the first to investigate MPs pollution in T. ovatus aquaculture. DNA sequencing and bioinformatics analysis confirmed the effect of microbial colonization of MPs on the intestinal flora of T. ovatus. The MPs detected in the gut wet weight (w.w.) of golden pompano (546 ± 52 items/g) were mainly pellets and fragments of blue or green, whereas the sediment MPs dry weight (d.w.) (4765 ± 116 items/kg) were mainly black fibers. The MPs richness in the sediment gradually increased from the open-sea aquaculture area to the estuarine aquaculture area and was positively correlated with the MPs richness in the intestinal tract of golden pompano. MPs 20-200 µm were the most common in the gut and sediment. The intake of MPs increased the abundance of Proteobacteria and decreased that of Firmicutes in the intestinal flora. The functional compositions of MP-colonizing microbes and gut microbiota were similar, suggesting that the two communities influence each other. Network analysis further confirmed this and revealed that Vibrio plays a key role in the intestinal flora and surface microorganisms of MPs. Overall, the intake of MPs by aquatic animals not only affects the intestinal flora and intestinal microbial function, but also poses potential risks to aquaculture.