Cadmium (Cd) poses a great threat to the breeding of aquatic economic animals. The present study aimed to explain the antagonistic effects of selenium-enriched Lactobacillus plantarum (SL) on Cd toxicity through the expression of oxidative and inflammatory factors. A total of 225 Bulatmai barbel Luciobarbus capito (L. capito) were divided into 3 groups, namely, the control group, the Cd group (Cd, 0.05 mg·L⁻¹), and the SL + Cd group (Cd, 0.05 mg·L⁻¹; Nano Se, 5 mg·kg⁻¹; L. plantarum, 10⁵ CFU·g⁻¹). The experiment lasted for 28 d, Sampling at 14 and 28 d, respectively. The results showed that Cd exposure caused obvious pathological damage to the liver and kidney, and the serum parameter ALT increased significantly (p < 0.05). In the Cd group, the concentration of Cd in the kidney was significantly increased (p < 0.05), and the activities of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) in the kidney and gill were significantly decreased; malonaldehyde (MDA) increased significantly (p < 0.05) Then the mRNA expression levels in the kidney and liver were measured. Cd exposure significantly decreased the mRNA expressions of SOD, CAT, GSH-Px, HO-1, I-κBα, and Nrf2 (p < 0.05). The Cd-treated group showed significantly increased NF-kBp65, TGF-β, IL-8, IL-1, Keap1, and TNF-α expression levels. SL significantly alleviated the changes in the above indicators. The results of this study suggest that SL can trigger the Nrf2 signalling pathway and NF-kB signalling pathway to alleviate Cd toxicity. SL might be a potential drug for the treatment of Cd poisoning.

The morphology of sperm and early embryo development of shellfish can provide guidance for classification and biological reproduction. In this study, scanning electron microscopy and light microscopy were used to determine the shape of the sperm, characterize the embryonic development, and measured the size of the mature eggs and the D-shape larvae of four different clam species (Paphia schnelliana, Lutraria sieboldii, Antigona lamellaris, and Paphia textzle). The results showed that these four clam species differ in sperm morphology and the size of the mature eggs and the Dshape larvae (P<0.01). There were also differences in embryonic development time and morphology. This analysis of spermatozoa morphology, egg size, D-shaped larvae size, and embryo development in these four different clam species provides the basis for classification and future breeding efforts.

The aim of this study was to compare total carotenoid content (TCC) in tissues, and its correlation with shell color between four different shell color strains of Pinctada fucata. A total of 120 individuals (30 golden shells, 30 red shells, 30 black shell and 30 white shells) of P. fucata of similar size were evaluated. In this study, stomach, gill, adductor, and mantle were used for measuring the determination of TCC. The color measurements were taken from both the nacre shells and cuticle shells. The results showed that TCC varies significantly among four different tissues and the four different shell color strains (P < 0.05). A significant difference between the cuticle shell colors of the four different shell color strains of P. fucata was observed (P < 0.05), while the nacre shell colors of four shell strains were similar (P > 0.05). In the present study, results indicated that the TCC of P. fucata was significantly related to tissue and cuticle shell colors (P < 0.001), but not related to nacre shell colors (P > 0.05). TCC relating to the cuticle shell color suggested that increasing or decreasing TCC in P. fucata through selective breeding of cuticle shell color was feasible, and it could be significant both for food for humans, and the cultivation of high-quality pearls.

Cold stress is a key environmental constraint in aquaculture, but integrated host responses linking oxidative status, intestinal microbiota, and hepatic metabolism remain insufficiently characterized in Luciobarbus capito. This study aimed to evaluate the biochemical, microbial, and metabolic responses of L. capito to acute low-temperature exposure. Fish were exposed to 12 °C for 96 h, with fish maintained at 22 °C as controls; hepatic antioxidant indices, serum biochemical parameters, intestinal microbiota based on 16S rRNA gene sequencing, and liver metabolomic profiles were analyzed. Cold exposure reduced hepatic total superoxide dismutase (T-SOD) and catalase (CAT) activities and increased malondialdehyde (MDA) content, while serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities increased and acid phosphatase (ACP) activity decreased. The intestinal microbiota showed reduced richness and compositional shifts, including decreased Cetobacterium and increased Pseudomonas. Liver metabolomics identified 172 differential metabolites, with enriched pathways related to glycerophospholipid metabolism, α-linolenic acid metabolism, pantothenate and CoA biosynthesis, and ascorbate and aldarate metabolism. Correlation analysis indicated significant associations between altered bacterial genera and hepatic metabolites. These results suggest that acute cold stress disrupts oxidative balance, intestinal microbial composition, and hepatic metabolism in L. capito, providing an integrated view of associated physiological and metabolic responses to low-temperature stress.