Jun Wang,Xuan Li,Peng Li,Lianxu Li,Lingchao Zhao,Shaoguo Ru,Dahai Zhang
Microplastics and polychlorinated biphenyls are ubiquitous in the marine environments. To illuminate their combined biological impacts, juvenile Japanese flounder ( Paralichthys olivaceus ) were exposed to 500 ng/L PCBs alone or 500 ng/L PCBs plus 2, 20, and 200 μg/L 10-μm porous MPs for 21 days. Compared to PCBs alone, co-exposure to PCBs and 20, 200 μg/L MPs reduced fish body length and body weight, and the concurrence of MPs aggravated PCBs-induced thyroid-disrupting effects, including significantly decreased L-thyroxine and L-triiodothyronine levels, more severe damage to the thyroid tissue and gill morphology, and disturbance on the expression of hypothalamus-pituitary-thyroid axis genes. The PCBs concentrations in the seawater were decreased dramatically with the increase of MPs concentrations, confirming that MPs absorbed PCBs from the seawater. Our results demonstrated that MPs enhanced the thyroid disruption of PCBs, suggesting that the risk of MPs and thyroid-disrupting chemicals on marine organisms should be paid more attention.
Ube3a is a member of the E3 ubiquitin ligase HECTc family, and its role has been established in neurodevelopmental disorders. However, studies on its role in Japanese flounder are scarce. Thus, in this study, the ube3a of Japanese flounder was cloned, and its role in conferring resistance against Chinook salmon bafnivirus (CSBV) was analyzed. Japanese flounder ube3a encoded a protein containing 834 amino acids. Interestingly, its homology with the Atlantic halibut was determined to be 94%. In addition, there were differential expressions of ube3a in different tissues of Japanese flounder, with the highest expression level observed in the fin, followed by the gills and skin ( P ≤ 0.05). Subcellular localization analysis revealed that Ube3a is a cytoplasmic protein. We established an in vitro CSBV infection model using Japanese flounder gill cell line (FG). After ube3a overexpression, the viral load was significantly lower than that of the control group ( P ≤ 0.05). Contrastingly, after incubation of FG cells with an E3 ubiquitin ligase inhibitor, the viral load was significantly higher than in the control group ( P ≤ 0.01). Then, the expression levels of nf-κb , traf3 , and tnf-α after incubation with an E3 ubiquitin ligase inhibitor were examined. The results demonstrated that ube3a may exerted a significant antiviral effect in Japanese flounder via the ubiquitination pathway.
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