Salvianolic acid B (Sal B), as one of the main water-soluble components of Salvia miltiorrhizae, has significant pharmacological activities, including antioxidant, free radical elimination and biofilm protection actions. However, the protective effect of Sal B on Nile tilapia and the underlying mechanism are rarely reported. Therefore, the aim of this study was to evaluate the effects of Sal B on antioxidant stress, apoptosis and autophagy in Nile tilapia liver. In this experiment, Nile tilapia were fed diets containing sal B (0.25, 0.50 and 0.75 g·kg⁻¹) for 60 days, and then the oxidative hepatic injury of the tilapia was induced via intrapleural injection of 50 g·kg⁻¹ cyclophosphamide (CTX) three times. After the final exposure to CTX, the Nile tilapia were weighed and blood and liver samples were collected for the detection of growth and biochemical indicators, pathological observations and TUNEL detection, as well as the determination of mRNA expression levels. The results showed that after the CTX treatment, the liver was severely damaged, the antioxidant capacity of the Nile tilapia was significantly decreased and the hepatocyte autophagy and apoptosis levels were significantly increased. Meanwhile, dietary Sal B can not only significantly improve the growth performance of tilapia and effectively reduce CTX-induced liver morphological lesions, but can also alleviate CTX-induced hepatocyte autophagy and apoptosis. In addition, Sal B also significantly regulated the expression of genes related to antioxidative stress, autophagy and apoptosis pathways. This suggested that the hepatoprotective effect of Sal B may be achieved through various pathways, including scavenging free radicals and inhibiting hepatocyte apoptosis and autophagy.

Aquaculture environment plays important roles in regulating the growth, morphology, nutrition, and flavor of aquatic products. The present study investigated growth, morphology, nutrition, and flavor formation in largemouth bass (Micropterus salmoides) cultured in the ponds with (EM group) and without (M group) the submerged macrophytes (Elodea nuttallii). Fish in the EM group showed a significantly greater body length, higher growth rate, and lower hepatosomatic index than those in the M group (p< 0.05). Moreover, compared with fish in the M group, those in the EM group showed improved muscle quality with significantly elevated levels of crude protein, total free and hydrolysable amino acids, and polyunsaturated fatty acids (p < 0.05). Specifically, certain amino acids related to flavor (Glu, Asp, Ala, and Arg) and valuable fatty acids (C18:2, C18:3n3, C20:3n3, and C22:6) were more abundant in the EM group (p < 0.05). In addition, the levels of 19 volatile (p < 0.05) were significantly higher in the EM group than in the M group. Therefore, E. nuttallii significantly improved growth, morphological traits, nutritional components, and characteristic flavor in largemouth bass, indicating the superior nutritional value and palatability of fish cultured with submerged macrophytes.

The Chinese mitten crab, Eriocheir sinensis (H. Milne Edwards, 1853), is an economically important aquaculture species in China. It is a significantly desirable species by Chinese consumers that causes a high demand for environmentally friendly culture farming. In aiming to break through bottlenecks, i.e., “pond moss” and cyanobacteria, we investigated the microbial community and plankton composition of ponds with filamentous algae and cyanobacterial blooms. As results, we found Actinobacteria, Proteobacteria, and Bacteroidetes were dominant bacterial phyla, while Chlorophyta and Bacillariophyta were dominant phytoplankton phyla in E. sinensis ponds. Nitrospira sp., Flectobacillus sp. BAB-3569, Staphylococcus warneri, Fusarium oxysporum, Gromochytrium mamkaevae, and Rhizophydium sp. JEL317 were screened as bioindicators for harmful algal blooms. We found a close relationship between water quality parameters and the species composition of bacteria and zooplankton in the present study. Specifically, total nitrogen and total ammonia nitrogen significantly affected the bacterial community composition, while total phosphorus contributed to the phytoplankton community composition. We further indicated the potential competitive inhibition of Chlamydomonadales on the direct regulation of the control of harmful algal blooms. Finally, we suggested a combination of probiotics and microalgae, e.g., C. vulgaris, to prevent and control potential risks in the culture of E. sinensis. In conclusion, the present study deepened our understanding of harmful algal blooms in aquaculture ponds and suggested the baseline indications for the prevention and control of algal blooms.

The intestine is an important immune organ of aquatic animals and it plays an essential role in maintaining body health and anti-oxidative stress. To investigate the toxic effects of deltamethrin in intestinal tissue of Chinese mitten crabs (Eriocheir sinensis), 120 healthy crabs were randomly divided into two experimental groups (blank control group and deltamethrin-treated group), with three replicates in each group. After being treated with deltamethrin for 24 h, 48 h, 72 h, and 96 h, intestinal tissues were collected aseptically to assess the effects of deltamethrin on oxidative stress, immunity, apoptosis-related genes, and the structure of microflora in intestinal tissues. Additionally, correlations between gut microbiota composition and intestinal tissue damage-associated genes were analyzed. The results demonstrated that prolonged exposure to deltamethrin induced oxidative stress damage in intestinal tissue. Compared with the blank control group, the expression of autophagy-related genes B-cell lymphoma/Leukemia-2 (bcl-2), c-Jun N-terminal kinase (jnk), Microtuble-associated protein light chain 3 (lc3c), Cysteine-dependent Aspartate-specific Protease 8 (caspase 8), BECN1(beclin1), oxidative stress damage-related genes MAS1 proto-oncogene (mas), Glutathione Peroxidase (gpx), kelch-like ECH-associated protein 1 (keap1), Sequestosome 1 (p62), Interleukin-6 (il-6), and immune-related genes Lipopolysaccharide-induced TNF-alpha Factor (litaf), Heat shock protein 90 (hsp90) and prophenoloxidase (propo) in the deltamethrin treatment group were significantly up-regulated at 96 h (p < 0.05 or p < 0.01). Additionally, 16S rRNA sequencing showed that the diversity of intestinal flora in the deltamethrin-treated group was significantly higher compared with the blank control group (p < 0.01). Analysis of the differences in the composition of intestinal flora at the genus level showed that the relative abundance of Candidatus Bacilloplasma in the deltamethrin treatment group was significantly lower than that in the blank control group (p < 0.01). In contrast, the relative abundances of Flavobacterium, Lachnospiraceae_NK4A136_group, Acinetobacter, Chryseobacterium, Lacihabitans, Taibaiella, Hydrogenophaga, Acidovorax, and Undibacterium were significantly higher than those in the blank control group (p < 0.05 or p < 0.01). Pearson correlation analysis revealed that Malaciobacter, Shewanella, and Prevotella exhibited significant positive correlations with gene indicators (jnk, gpx, lc3c, litaf, hsp90), while Dysgonomonas, Vibrio, and Flavobacterium demonstrated significant negative correlations with multiple gene indicators (caspase 8, p62, il-16, keap1, jnk, etc). These results demonstrate that deltamethrin significantly impacts the gut microbiota, immune function, and antioxidant capacity of E. sinensis. The changes in gut microbiota have correlations with the biomarkers of intestinal tissue injury genes, indicating that gut microbiota plays a crucial role in deltamethrin-induced intestinal tissue damage. These insights contribute to a better understanding of the ecological risks associated with deltamethrin exposure in aquatic organisms.

The American shad (Alosa sapidissima) is an important freshwater food fish, yet little is known about its postmortem quality. We sampled the meat of American shad and tracked the changes in color, pH, shear stress, cooking loss and total volatile basic nitrogen (TVB-N) over 48 h of storage at 24 °C (unrefrigerated) or 4 °C (refrigerated). Thereafter, the essential nutrients, fatty acids, hydrolyzed amino acids, free amino acids, and electronic tongue were evaluated. The results show that the L* and a* values decreased as storage progressed, while the b* value increased. The shear force decreased, but cooking losses in the American shad increased; the TVB-N value continuously increased over the duration of storage. The TVB-N content deviated from the freshness range at 48 h when stored at 24 °C. At 24 °C, the sweet amino acids reached a maximum at 6 h, and the bitter amino acids reached a maximum at 48 h. At 4 °C, there was a significant difference in bitter free amino acids at 48 h (p < 0.05). The nutrient composition showed that the contents of fat and protein decreased, whereas the water content increased. These results showed that American shad should be eaten within 6 h when stored at 24 °C, while American shad stored at 4 °C can maintain freshness for 24 h to obtain better product quality.

This study employed multi-omics analysis to systematically evaluate the toxic effects of intraperitoneal injection of MC-LR on GIFT tilapia. The results showed that 96 h post injection, serum levels of aspartate GOT, GPT, LYZ, T-AOC, and SOD significantly decreased (p < 0.05). In contrast, hepatic levels of CAT and MDA significantly increased. The 16S rDNA sequencing method revealed a significant reduction in the α diversity of the intestinal microbiota. At the phylum level, the relative abundances of Firmicutes and Bacteroidota significantly decreased; at the genus level, several genera, including Bacteroides and Pseudomonas, also exhibited significant changes. Functional prediction indicated that the affected pathways were primarily related to metabolism and disease. Additionally, targeted metabolomics analysis showed a significant decrease in the levels of several SCFAs, such as butyric acid. Correlation analysis further elucidated the complex interactions between the intestinal microbiota, biochemical indicators, and SCFA metabolism. Overall, the study demonstrated that MC-LR induced oxidative stress and liver damage and led to intestinal microbiota imbalance and metabolic dysfunction in GIFT tilapia.