Jian-sheng Huang’s research while affiliated with Guangdong Ocean University and other places

In intensive aquaculture, ammonia nitrogen (NH₃-N) is a major pollutant, causing oxidative stress and immune damage to aquatic organisms. The liver is crucial in protecting against biotic and abiotic stresses, but the response mechanisms to ammonia stress in juvenile four-finger threadfin (Eleutheronema tetradactylum) are not well understood. This study investigated these mechanisms by examining liver tissue structure, enzyme activities, and metabolomic changes in response to ammonia stress. Juvenile four-finger threadfin (7.4 ± 0.6 g) were divided into control, NH₃-N stress (50% LC50 96 h, 10 ± 0.4 mg/L), and postexposure recovery groups. Stress durations of 12, 24, 48, and 96 h were evaluated, followed by 48 h recovery. Prolonged ammonia stress led to increased liver tissue damage, including disordered hepatocyte arrangement, swelling, necrosis, and the disappearance of nucleoli. After 48 h recovery, liver damage was alleviated but did not fully return to control levels, suggesting that the toxic effects of ammonia are recoverable yet persistent. Antioxidant enzyme activities (superoxide dismutase, catalase, and glutathione peroxidase) initially showed significant increases peaking at 24 h after stress, before declining by 96 h. Malondialdehyde levels rose initially and remained elevated compared with controls. After 48 h of recovery, antioxidant enzyme activity had not returned to control levels, indicating inadequate recovery from ROS-induced stress. Metabolomic analysis revealed 1219 significantly different metabolites in the 96 h stress group, with increases in L-histidine, L-threonine, and cholesterol. In the recovery group, 904 metabolites differed from controls, with notable reductions in urea and choline. The key affected pathways included amino acid, lipid, and nucleotide metabolism. This study elucidates the toxic effects of ammonia nitrogen on juvenile four-finger threadfin and their adaptive responses through physiological and metabolomic changes, providing insights for aquaculture practices and breeding ammonia-tolerant strains.

This study evaluated the effects of hypoxia on the heart of juvenile four-finger threadfin (Eleutheronema tetradactylum) through physiological and transcriptome analysis. Juveniles with an average weight of 122.82 g and length of 24.60 cm were used. Hypoxia significantly increased serum myocardial enzyme activities, including creatine kinase (CK), creatine kinase-MB isoenzyme, lactate dehydrogenase (LDH), and α-hydroxybutyrate dehydrogenase (HDBH). These indicators initially rose and then declined, reflecting cardiac stress and suggesting their potential as early hypoxia biomarkers for real-time aquaculture monitoring. Histological analysis revealed structural damage in myocardial fibers under hypoxia, with increasing severity over time. This underscores the need to minimize oxygen fluctuations to prevent cardiac tissue degeneration. Transcriptome analysis identified upregulated genes involved in cell communication, immune responses, and intracellular signaling, offering potential targets for breeding hypoxia-tolerant species. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis highlighted key pathways such as mitogen-activated protein kinase (MAPK), hypoxia-inducible factor-1 (HIF-1), endocytosis, and phagosome formation. The MAPK pathway plays a critical role in cellular stress responses, including survival, proliferation, and apoptosis. Hypoxia-induced activation of MAPKs like ERK, JNK, and p38 regulates stress-responsive genes. HIF-1 signaling regulates oxygen homeostasis, with HIF-1α stabilizing hypoxia-responsive genes such as VEGFA, which promotes vascular remodeling and enhances oxygen delivery. These findings collectively offer practical applications for enhancing aquaculture management, such as monitoring biochemical markers, adopting hypoxia-tolerant breeding, and adjusting environmental conditions to mitigate stress, ensuring better productivity and sustainability. This research provides a foundation for further studies on the molecular mechanisms of hypoxia stress in aquaculture species.

There has been a surge of research in the aquaculture industry investigating probiotic, prebiotic, and synbiotic interventions on the physiological mechanisms of fish, specifically digestive enzymes, oxidative stress, and antioxidant defense. In fish, probiotics have been shown to improve nutrient utilization and growth performance by stimulating digestive enzymes. Meanwhile, probiotics, prebiotics and synbiotics have also been studied for their ability to modulate oxidative stress and antioxidant defense mechanisms in fish, highlighting their multifaceted health benefits. This review identified current trends, research gaps, and future considerations in this evolving field. Although promising findings have been made, a significant research gap exists in understanding the specific role of probiotics prebiotics, and synbiotics in modulating digestive enzymes, oxidative stress, and antioxidant defense systems in a variety of fish species. As this study investigate into the existing body of literature, it becomes evident that while certain aspects of these interactions have been elucidated, a nuanced and comprehensive understanding still needs to be discovered. The variations in experimental design, species-specific responses, and the lack of standardized methodologies contribute to the complexity of the field. Digestive physiology and antioxidant defense mechanisms vary among different fish species, so future research should focus on species-specific responses to probiotic, prebiotic, and synbiotic formulations. It will also be possible to establish robust correlations between dietary interventions and observed effects through a systematic experimental design and methodology approach. Accordingly, further research is needed to understand the interactions between probiotics, prebiotics, and synbiotics in fish and digestive enzymes, oxidative stress, and antioxidant defense. Identifying research gaps and adopting standardized methodologies can help develop tailored strategies to optimize aquaculture fish health and growth performance.

Low temperatures pose a critical challenge to aquaculture operations, as they can significantly affect fish health and overall productivity. The study investigated the impact of low-temperature stress on juvenile golden pompano, focusing on serum indicators, intestinal microbiome, and intestinal transcriptome. With 180 fish divided into low-temperature (18 ± 0.5) ℃ and control (28 ± 0.5) ℃ groups, the gradual temperature decrease mimicked natural seasonal changes. Each group had 3 replicates, with 30 fish per replicate. Results indicated significant effects on serum indicators, including enzyme activity and ion concentrations. While intestinal flora richness was not drastically affected, the dominant flora composition changed. Transcriptome analysis revealed 1752 differentially expressed genes, with enrichment in pathways related to circadian rhythm, proteasome, metabolism, and signaling pathways. This research enhances understanding of cold stress responses in juvenile golden pompano, offering insights for tailored aquaculture management to promote robust and stress-resistant fish stocks. The findings contribute to sustainable aquaculture practices and lay the groundwork for future studies on temperature stress and fish health.

Feed is the main source of material and energy for farmed fish, and its nutritional value and balance are important factors affecting fish’s growth rate and physical health. In order to explore the effects of two different feed sources on the growth, serum biochemical indexes, liver antioxidant capacity, and lipid metabolism of young cobia fish, 300 young cobia fish with an initial body weight of 43.14 ± 1.25 g were selected for the experiment and randomly divided into two treatments. Each treatment had five replicates, and each replicate had 30 fish. They were fed with formulated feed and frozen fresh fish, respectively, for 12 weeks. The results showed that the weight gain rate, specific growth rate, and feed conversion rate of juvenile cobia fish fed with formulated diet were extremely significantly lower than those of the frozen fresh fish group ( P < 0.01 ), and condition factor was significantly lower than that of the frozen fresh fish group ( P < 0.05 ). However, protein efficiency rate, hepatosomatic index, and viscerosomatic index were significantly higher than those of frozen fresh fish group ( P < 0.05 ). The content of water, crude protein, and crude ash in the whole fish had no significant difference ( P > 0.05 ), while the content of crude lipid decreased significantly ( P < 0.05 ). The serum aspartate aminotransferase activity and sugar content of cobia in the formulated diet group were significantly higher than those in the frozen fresh fish group ( P < 0.05 ). In contrast, the total cholesterol, triglyceride content, alkaline phosphatase activity, and phosphorus content were significantly lower than those in the frozen fresh fish group ( P < 0.05 ). Compared with the frozen fresh fish group, the antioxidant enzyme activities in the liver of the formulated diet group were significantly decreased ( P < 0.05 ) except malondialdehyde (MDA) and the activity of fatty acid synthase, while there was no significant difference in the malate dehydrogenase. The study showed that under the experimental conditions, frozen fresh fish was more suitable for feeding juvenile cobia, and the formulated diet had adverse effects on the liver of juvenile cobia. Therefore, the nutritional composition of frozen fresh fish and the metabolic characteristics of cobia were used for reference to optimize and adjust the nutritional formula of juvenile cobia.

Nutrition, disease, and general wellbeing can be affected by the microbial communities associated with the digestive tracts of aquaculture species. Different sections of aquaculture species’ digestive tracts have distinctive surfaces and structures, which can change microbial communities. The present study examined the composition and distribution of bacterial species in the intestine of hybrid grouper (Epinephelus fuscoguttatus E. polyphekadion) and its aquaculture environment. Using high-throughput pyrosequencing, a 16S rRNA sequence analysis was performed on hybrid grouper foregut, midgut, and hindgut, as well as cultured water and feed. There were 610,452 sequences obtained from five components (foregut, midgut, hindgut, water, and feed). Among operational taxa (OTUs), 506 of them were detected in the foregut, 605 in the midgut, 510 in the hindgut, and 573 in aquaculture water and feed samples. A total of 113 were detected in 5 samples. A species annotation revealed that hybrid grouper intestinal tracts were dominated by Proteobacteria (67.3%–73.7%), Firmicutes (8.4%–14.0%), and Actinobacteria (6.9%–10.5%). In aquaculture culture water, Proteobacteria were predominant (36.3%), Actinobacteria (30.0%), and Planctomycetes (14.0%). Acinetobacter (1.4%–17.9%) and Photobacterium (32.0%–57.5%) dominated the intestine. Photobacterium (3.6%) and Mycobacterium (7.1%) dominated the water bacteria. The water and intestine contained five potentially pathogenic bacteria: Pseudomonas, Flavobacterium, Escherichia coli, Aeromonas bacteria, and Vibrio. The highest proportion of Vibrio was found in the water (1.7%), while Pseudomonas dominated the midgut (2.6%). Six potential probiotics were detected in the aquaculture water and intestine (Lactococcus, Streptococcus, Bdellovibrio, Lactobacillus, Bacillus, and Bacteroides). Aquaculture water and intestines contained Bacillus, Bacteroides, and Lactobacillus. According to the findings, the intestinal flora of hybrid grouper is closely correlated with its pond culture environment. Results from the study provide an experimental basis for the controlled breeding of hybrid groupers and the regulation of their microecological processes in the breeding environment deepen our understanding of the intestinal bacterial population of healthy hybrid groupers.

Water temperature plays a crucial role in the growth, survival, and reproduction of fish species, as they make up the majority of aquatic fauna. In this study, the effects of low temperature were studied on the functional state of juvenile golden pompano (Trachinotus ovatus) under low-temperature stress. The study was conducted at 28°C in the control group and 18°C in the cold group for 14 d to determine the intestinal tissue, digestive and antioxidant enzyme activities, and metabolites of juvenile fish. The results showed that: (1) the swelling degree of the muscle layer deepened and was congested with a longer low-temperature stress period. The folds were sparse, from slight swelling to shedding and deformation. The intestinal mucosa was necrotic and had vacuoles, and the number gradually increased. Serious erosion of the villi occurred. (2) The specific activities of digestive enzymes showed a downward trend. (3) The intestinal superoxide dismutase (SOD) activity, malondialdehyde (MDA) content, and glutathione peroxidase (GSH-Px) activity showed an upward trend. The intestinal catalase (CAT) activity showed a downward trend. (4) Compared with the control group, there were 28 metabolites in the cold group showing significant differences, among which Z, 11Z, 14Z-eicosatrienoic acid, stearic acid, and adrenic acid showed an upward trend. In contrast, spermidine and uracil showed a downward trend. Among the enriched metabolic pathways, the main differential pathways were unsaturated fatty acid biosynthesis, fatty acid biosynthesis, linoleic acid metabolism, pyrimidine metabolism, and β-alanine metabolism. According to metabolomic analysis, under low-temperature stress, the fish body improved the synthesis of unsaturated fatty acids and saturated fatty acids to adapt to a low-temperature environment and consumed spermidine to improve its immune ability to clear the peroxide generated by the synthesis of unsaturated fatty acids in the body so that the cells were protected from oxidative damage. After 14 days, low-temperature stress affected metabolites and enzyme activity indices in juvenile golden pompano. Low-temperature stress causes changes in intestinal antioxidants and digestive enzymes and damage intestinal tissues. As a result of this exploration of how low temperatures affect the juvenile golden pompano, the foundation is laid for future studies, such as the molecular mechanisms of low-temperature adaptation in fish species.

The current study was performed to assess the effects of dietary administration of ferulic acid (FA) on digestive enzyme activities, antioxidant capacity, morphology, immunity, and microbiota in the gut of hybrid grouper (Epinephelus fuscoguttatus♀ × Epinephelus polyphekadion♂). A total of 630 fish (9.51 ± 0.01 g) were allocated randomly to seven dietary treatments, each with three replicates. Experiment diets supplemented with FA at the levels of 0, 40, 80, 160, 320, 640, and 1280 mg kg−1 (FA0 (control), FA40, FA80, FA160, FA320, FA640, and FA1280), were fed to fish for 70 days. The results showed that dietary 80–160 mg kg−1 FA intake considerably augmented the enzymes activities of digestion (lipase, trypsin, amylase, and pepsin) and antioxidation (superoxide dismutase, glutathione peroxidase, and catalase) and the values of immune parameters (Immunoglobulin, C3 and lysozyme), as well as reduced malondialdehyde content, with respect to the control group (P

Cobia is an important cultured marine fish species in southern China. It is characterised by fast growth. Due to the effects of climate change on water oxygen levels and seawater temperatures, understanding the influence of environmental challenges on cobia culture has become very important. In this study, to explore the stress and adaptability of cobia (Rachycentron canadum) during hypoxia-reoxygenation conditions, the fish were exposed to an oxygen-deficient environment with dissolved oxygen (DO) level of 2.64 ± 0.25 mg/L. Liver tissue transcriptome sequencing was detected in the fish at acute hypoxia stress, after which fish were returned to normal DO levels (6.34 mg/L) for 8, 24, and 48 h. Comparative analysis of liver transcriptomes revealed that there were 1689, 651, 236, and 1150 differential genes in the hypoxia stress group (SC), reoxygenation-8h group (R8), reoxygenation-24h group (R24), and reoxygenation-48h group (R48), respectively. The differentially expressed genes were compared with the GO database. The main aggregated genes were related to gene ontology functional elements such as ribosome structural components, matrix-dependent cell migration, hormone activity, and oxidoreductase activity. The differentially expressed genes were compared with the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, and a total of 43,054 differentially expressed genes were found to be enriched in 212 cases. For the first time, gene expression patterns in the liver of a juvenile’s cobia were examined in response to hypoxia. The results of this study contribute to further clarifying hypoxia’s effects on the liver of marine fish.