Skin pigmentation is a critical determinant of quality and market value in farmed fish, while environmental stressors such as hypoxia can induce oxidative stress and metabolic disorders, thereby threatening fish health and aquaculture sustainability. The present study investigated the effects of dietary lutein and zeaxanthin on skin pigmentation, hepatic lipid metabolism, and oxidative stress responses in yellow catfish (Pelteobagrus fulvidraco) through a 50-day feeding trial followed by an acute hypoxia challenge. Fish (initial body weight: 25.98 ± 0.03 g) were randomly assigned to three experimental diets: a basal control diet (Con), or the basal diet supplemented with 0.2% lutein (Lut) or 0.2% zeaxanthin (Zea). Although no significant differences in growth performance were observed among dietary groups, skin yellowness and total carotenoid deposition in both skin and liver were significantly elevated in the Lut group (P < 0.05), followed by the Zea group. Lipidomic profiling revealed that both lutein and zeaxanthin supplementation modulated multiple lipid classes, including glycerophospholipids (GP), glycerolipids (GL), sphingolipids (SP), sterols (ST), and fatty acids (FA) in liver and skin tissues (P < 0.05). Skin lutein content exhibited strong positive correlations with phosphatidylcholine (PC) levels (R=0.978, P < 0.01) and the expression of lipid transport-related genes cd36 (R=0.978) and scarb1 (R=0.977, P < 0.01). Under acute hypoxic stress, fish fed Lut or Zea diets displayed significantly higher plasma SOD activity and lower levels of glucose, lactic acid, and MDA compared to the control group (P < 0.05). Moreover, lutein supplementation specifically upregulated the expression of antioxidant and anti-apoptotic genes (nrf2, sod, gpx, bcl2) while downregulating pro-apoptotic genes (p53, casp3) in the liver (P < 0.05). In conclusion, dietary lutein plays a more prominent role than zeaxanthin in enhancing skin pigmentation and antioxidant defense in yellow catfish, and its functional efficacy is closely associated with lipid metabolism and carotenoid transport mechanisms.

Temperature is a crucial environmental factor for poikilothermic aquatic species and can affect their protein utilization. This study examined the impacts of temperature (optimal 27 degrees C vs. high 33 degrees C) and protein blends (formulated at 1:1:8:2, 1:1:6:4, and 1:1:4:6 ratios using Chlorella meal, Tenebrio molitor meal, Clostridium autoethanogenum protein, and cottonseed protein concentrate as fishmeal substitutes) on growth performance, health status, and gut microbiota of gibel carp. Healthy fish (3.45 +/- 0.03 g) were randomly distributed among 24 tanks (30 fish/tank), with each temperature condition assigned four experimental diets and each treatment replicated in three tanks for an 8-week feeding trial. High temperature (33 degrees C) enhanced feed intake and final body weight, but reduced feed efficiency (FE) and the apparent digestibility coefficients of crude protein and total essential amino acid. It also decreased intestinal superoxide dismutase, glutathione, and glutathione peroxidase activities, increased malondialdehyde content and elevated heat shock protein 70 (HSP70) and HSP90 levels. Moreover, it down-regulated il10 and tgf beta transcription and reduced villus height with lymphocyte infiltration. Furthermore, there was an enrichment in phyla Proteobacteria and Actinobacteriota and genera Mycobacterium, while beneficial Cetobacterium abundance was decreased. Compared to fishmeal, the protein blend in a 1:1:6:4 ratio improved FE and protein retention efficiency at 33 degrees C. Concurrently, this blend augmented the abundance of phyla Firmicutes and genera Clostridium_sensu_stricto_12. In summary, although elevated temperature enhanced growth via hyperphagia, it substantially compromised intestinal health and nutrient utilization. This adverse effect was mitigated through nutritional intervention with the optimized 1:1:6:4 protein blend formulation.

This study investigated the effects of dietary leucine on growth, lipid metabolism, and reproductive performance in female yellow catfish (Pelteobagrus fulvidraco) broodstock. Leucine deficiency significantly compromised growth and feed utilization (P < 0.05). Plasma aspartate aminotransferase activity was lowest, whereas albumin concentration was highest, in fish fed the diet containing 3.80% leucine. Although hepatic lipid deposition increased, plasma triglycerides declined with the increasing dietary leucine levels. Notably, the mesenteric fat index exhibited a significant linear decrease with increasing dietary leucine (3.18%–4.22%), suggesting a tissue-specific lipid-lowering effect conducive to reproduction. Consequently, dietary leucine supplementation significantly enhanced fertilization rates, hatching rates, and larval viability. Mechanistically, these improvements were attributed to the upregulation of ovarian steroidogenic genes (ar, lhr, and 3β-hsd) and elevated plasma follicle stimulating hormone (FSH) and estradiol (E2) levels, implicating the FSH-E2 axis. Crucially, the optimal leucine requirement for yellow catfish exhibited a hierarchical increase: 3.60% for fertilization, 3.88% for growth, and 4.02% for larval viability. This suggests higher maternal reserves are critical for supporting late-stage embryogenesis and offspring morphogenesis. Therefore, a dietary leucine level of 4.02% is recommended to simultaneously minimize mesenteric fat deposition and ensure superior growth performance, reproductive success and offspring quality in female yellow catfish.

This study was designed to explore the underlying mechanisms of Asarum in treating oral ulcers (OU) by integrating network pharmacological analysis, the gene expression omnibus database, molecular docking, and dynamics simulation techniques. Network pharmacology was used to identify core targets of the active components of Asarum for OU treatment. Subsequently, single-cell genomic analysis was performed to investigate the distribution and expression of these core targets in oral mucosal tissue cells. Molecular docking was employed to assess the binding affinity between Asarum's active ingredients and the identified core targets. Transcriptomic data were used to validate the differential expression of these core targets in OU. Finally, molecular dynamics simulations were conducted on promising binding systems to evaluate the stability of their interactions. Eight active pharmacological ingredients of Asarum were identified, along with 135 corresponding gene targets. Intersection analysis of OU-related gene targets resulted in 92 drug-disease interaction genes. The CytoNCA plugin was used to select 14 core targets. Molecular docking simulations indicated moderate-to-strong binding affinities between these core targets and the active ingredients of Asarum. Differential expression analysis of OU data from the gene expression omnibus database revealed that CYP3A4 and AKT1 were differentially expressed in the disease group, providing an effective diagnostic model. Molecular dynamics simulations further demonstrated that the CYP3A4-kaempferol complex exhibited superior stability. Our study successfully predicted the potential targets of Asarum in the treatment of OU and provided a comprehensive exploration of their mechanisms of action. Among the active ingredients, kaempferol and the target gene CYP3A4 appear to hold the greatest promise for therapeutic applications in OU treatment. This study lays a strong foundation for future studies on the efficacy of Asarum in treating OU.

Stocking density and feed protein sources are critical in aquaculture. This study investigated their effects on growth, stress response, and protein utilization in gibel carp. Fishmeal served as the control diet (diet 1), while it was replaced by a blend of Tenebrio molitor meal, Chlorella meal, Clostridium autoethanogenum protein, and cottonseed protein concentrate in various ratios: 1:1:8:2 (diet 2), 1:1:6:4 (diet 3), and 1:1:4:6 (diet 4). Fish were raised at either a low stocking density (100 fish/cage, 20 fish/m3) or a high density (400 fish/cage, 80 fish/m3), with 6000 fish in total. The interaction of stocking density and diet affected growth and protein utilization. At a stocking density of 20 fish/m3, diet 2 effectively replaced fishmeal without compromising growth performance. At 80 fish/m3, only diet 3 achieved full fishmeal replacement without negative impacts on growth. High stocking density induced chronic stress, as seen by lower plasma glucose and higher muscle heat shock protein 70 and lactate levels. It also impaired intestinal function and muscle growth at the transcript level, reducing villus height and resulting in poorer growth performance. Diet 4 decreased trypsin and chymotrypsin activities, lowered villus height and the villus height/crypt depth ratio, and reduced plasma and muscle amino acid levels. It also downregulated genes involved in muscle protein synthesis, leading to reduced protein utilization. In conclusion, the optimal protein blend ratio was 1:1:8:2 ​at lower stocking densities and 1:1:6:4 ​at higher stocking densities, both of which achieved growth performance comparable to fishmeal. This density-specific protein blending strategy offers a scalable approach to formulating fishmeal-free feeds for intensive aquaculture systems without compromising productivity.

High-fat diets have been widely used in aquaculture because of their protein-sparing effect. However, high-fat diets have some negative effects on flesh quality in farmed fishes. This study investigated the potential of exercise to ameliorate the negative effects of a high-fat diet on the flesh quality of channel catfish (Ictarulus punctatus). A total of 120 channel catfish (54.58 ± 0.32 g) were randomly allocated to four treatments with triplicate tanks (10 fish per tank). Channel catfish were fed either a control diet (crude lipid = 6 %) or high-fat (HF) diet (crude lipid = 11 %) under two conditions: voluntary swimming (water velocity = 0.84 cm/s, 0 BL/s) and exercise (water velocity = 20.84 cm/s, 1 BL/s) for 58 days. We found that long-term intake of a HF diet adversely altered muscle composition and texture regardless of exercise, while impairing nutritional value and antioxidant capacity of voluntarily swum fish. However, the adverse effects observed with the HF diet on protein synthesis signaling (s6k1), essential amino acids, and total amino acids were attenuated with exercise. The HF diet promoted fasn expression and inhibited lipid catabolism (lpl and cpt1b) in the voluntarily swum fish only. Exercise reduced lipid accumulation in the muscle by inhibiting lipid synthesis-related gene expression (acaca and srebp1). Notably, exercise also inhibited fasn expression under the HF diet. These modulations were related to the activation of the AMPK/SIRT1/PGC-1α pathway. Moreover, exercise increased the levels of ARA, EPA, DHA, and n-3 PUFAs in muscle under the HF diet, thereby enhancing its nutritional value. Additionally, exercise increased muscle collagen content and improved muscle cellularity by upregulating the expression of genes related to myofiber development (myod1 and myhc). Under the HF diet, exercise also suppressed the expression of mstna and mstnb. These modulations ultimately enhanced flesh hardness and improved overall texture. Furthermore, exercise increased taste-active free amino acids and decreased off-flavors in fillets regardless of diet, while increasing aromatic flavor substances under the HF diet, thereby improving sensory qualities. Exercise also elevated muscle catalase levels and improved muscle antioxidant capacity under the HF diet. Our study suggests that exercise effectively alleviates the adverse effects induced by a HF diet on the flesh quality of channel catfish.

The fish intestine acts as a barrier in response to stress from the external environment. Largemouth bass (Micropterus salmoides) is a widely farmed economically important fish species. Juvenile largemouth bass are highly sensitive to temperature changes. Still, little is known about the effects of temperature stress on the immune function and the response of the intestinal microbiota in juvenile largemouth bass. To evaluate the effects of temperature stress on intestinal histology, immune response, microbiota, and inflammation of juvenile largemouth bass, this study comprised four treatment groups: 24 degrees C (the light cold-stress group), 27 degrees C (the optimal temperature group), 30 degrees C (the light heat-stress group), and 33 degrees C (the severe heat-stress group). The results indicated that the intestinal tissues of juvenile largemouth bass were damaged by temperature stress. The temperature-stress groups showed a significant decrease in the protein levels of MUC2, ZO-1, and Occludin, indicating that temperature stress damages the intestinal mucosal layer and tight junction structures. Heat stress increased the activities of immune-related enzymes, and the temperature-stress groups exhibited significantly higher levels of CD4, MPO, and immune-related genes, indicating damage to the intestinal immune barrier. Besides, the temperature-stress groups demonstrated elevated expression levels of inflammatory and apoptotic genes, and the corresponding protein levels were also significantly increased. The relative abundance of beneficial bacteria in the intestinal microbiota increased, while the presence of opportunistic pathogens decreased under temperature stress. The changes in the relative abundance of intestinal microbiota were significantly correlated with immune-related enzymes, inflammatory genes, and apoptotic genes. These findings indicate that temperature stress can damage the intestinal physical barrier of juvenile largemouth bass, disrupt the structure and species composition of the intestinal microbiota, and potentially impair the functioning of the intestinal immune barrier. The results of this study will increase our understanding of the underlying mechanisms of the intestinal immune response to ambient temperature stress in temperature-sensitive juvenile fish.

This study aimed to elucidate the molecular mechanisms underlying hepatic adaptation in mandarin fish during early domestication by integrating transcriptomic and lipidomic analyses. Fish were fed either live prey (C) or artificial diets (F), and liver samples were collected on days 7 and 20 of the feeding trial to assess dynamic transcriptional and metabolic responses. No significant differences in body weight were observed between groups. Transcriptomic analysis revealed 861 differentially expressed genes on day 7 and 2922 on day 20, while lipidomic profiling identified 218 and 421 differentially abundant metabolites, respectively. Integrated multi-omics analysis revealed that steroid biosynthesis (particularly cholesterol synthesis), glycerophospholipid metabolism and sphingolipid signaling pathway were central to hepatic adaptation during domestication. Moreover, immune-related pathways, particularly the IL-17 signaling pathway and its downstream effectors (nfκb, tnfα, il-1β), were increasingly activated over time. In general, this study reveals continuous transcriptional and metabolic reprogramming in the liver during early domestication, providing insights into the molecular basis of dietary adaptation in mandarin fish. These findings lay a foundation for developing nutritionally optimized formulated feeds that support sustainable commercial production of mandarin fish.

The viability of fish during their early developmental stages is pivotal for population recruitment, a period during which individuals are frequently confronted with significant risks of starvation. There is limited knowledge regarding Odontobutis potamophila food selectivity before its transition to feeding on fish. Thus, this study aimed to elucidate its prey composition and diet shift from 0 to 22 days after hatching. We also examined early allometric growth patterns to confirm whether there was a correlation between the rapid onset of exogenous feeding in juvenile carnivorous fish and the earlier appearance of inflection points in various morphological traits. Cluster analysis showed a gradual shift in prey composition from nauplii to predominantly cladocerans and copepods as individuals grew. This adaptive shift in diet revealed a mechanism whereby the larger the individual, the larger the size of the bait ingested, and the faster the growth rate. The results of the allometric growth study demonstrated that O. potamophila emerged from the membrane with a total length of 6.53 +/- 0.51 mm and a body weight of 1.93 +/- 0.56 mg. The positive allometric growth of body weight relative to total length provides the required energy for organ development and onset of the juvenile stage. Feeding commences at one day posthatching, with the yolk sac fully depleted by day 6, thereby facilitating the transition into the exogenous nutritional phase as early as possible. The initial manifestation of certain morphological growth inflection points occurred predominantly around 10 days of age, concomitant with the advent of a shift in feeding habits. The prey composition, diet shifts, and growth patterns of early individuals with equilibrium strategy, represented by O. potamophila, have important implications for improving the survival of early life stages, thereby providing new strategies for population replenishment.

This study aimed to investigate the effects of dietary protein source (DPS) and extrusion temperature (ET) on the physical qualities of extruded grass carp feed and the growth performance, tissue composition, and gut microbiota of these animals. We used a 2 × 2 factorial experimental design, with DPSs consisting of mostly plant or fishmeal proteins extruded at 120 °C (DP1 and DA1 diets) or 140 °C (DP2 and DA2 diets) for grass carp. The growth trial was performed for 9 weeks, and the gut microbiota trial lasted 4 weeks. Compared with the fishmeal-based diets, the plant protein-based diets produced higher expansion ratios (P < 0.001). A high ET also improved the expansion ratio (P < 0.001) and significantly decreased the feed pellet bulk density (P < 0.001). The DP2 diet had the highest hardness and water solubility index and the lowest water absorption index. The DP1 diet exhibited the lowest protein and phosphorus apparent digestibility coefficients (ADCs). The ET significantly affected the ADCs for the plant protein-based diets, but not for the fishmeal-based diets. Grass carp fed the DP1 diet presented the lowest weight gain and specific growth ratio. The interactions between DPS and ET affected the final body weight (P = 0.030), protein efficiency ratio (P = 0.011), and feed efficiency (P = 0.016), and these indices were significantly greater in grass carp fed the DP2 diet than in those fed the DP1 diet. However, DPS and ET did not affect the concentrations of crude protein or amino acids in the dorsal muscle. Compared with grass carp fed plant-based diets, those fed fishmeal-based diets presented greater fat contents in the muscle (P = 0.011) and liver P = 0.037), and a greater hepatosomatic index (P = 0.003). The interaction of DPS and ET influenced the viscerosomatic index (VSI, P = 0.001), with the highest VSI found after feeding the DA2 diet. DPS (P = 0.001) but not ET (P = 0.172) significantly affected the gut microbial communities, although the plant protein-based diets with increased ET resulted in more differential taxa and greater differences in the abundances of the core microbiota in grass carp compared to the fishmeal-based diets. These results indicate that improving the ET of plant protein-based diets can alter the physical qualities of the diets, further affecting the gut microbiota, and enhancing the growth performance of grass carp. These findings reveal that higher ETs are needed for plant protein-based diets than for fishmeal-based diets, which is a valuable guideline for feed production.

High-plant protein diets can present certain limitations for the growth and health of aquaculture species. By incorporating essential amino acids into grass carp feed based on amino acid balance, this study investigated their role in alleviating the previously mentioned challenges. The control diet consisted of soybean meal, rapeseed meal, and cottonseed meal as the major protein sources. In contrast, the experimental diet was fortified with 0.21 % lysine, 0.32 % methionine, and 0.23 % threonine. A total of 300 grass carp (61.3 g) were randomly allocated into six net cages and fed with either the control or experimental diet for eight weeks. The results demonstrated that dietary amino acid supplementation improved weight gain rate, specific growth rate, and feed efficiency (P < 0.05). Moreover, it downregulated the mRNA expression of the TLR/MyD88/NF kappa B signaling pathway and pro-inflammatory cytokines (P < 0.05), mitigating intestinal inflammation. Regarding the intestinal microbiota, this treatment increased ACE and Chao indices, accompanied by an elevation in the abundance of Firmicutes and a concomitant reduction in Spirochaetota and Brevinema (P < 0.05). Furthermore, the diet with amino acid supplementation increased hepatic sm transcript levels and cholesterol contents (P < 0.05). It also stimulated the mRNA expression of the cyp7a1, leading to elevated levels of hepatic cholic acid, taurocholic acid, taurochenodeoxycholic acid, and glycochenodeoxycholic acid 3 sulfate disodium salt and increased intestinal bile acid concentrations (P < 0.05). In summary, the essential amino acid supplementation reshaped the bile acid cycle of the host by promoting hepatic cholesterol and bile acid synthesis and influencing the composition of the gut microbiota, alleviated intestinal inflammation, and improved the growth of grass carp. The findings revealed that optimizing the amino acid balance in feed formulations can improve fish growth performance and health while lowering production costs, thereby supporting the sustainable advancement of the aquaculture sector.

Fish are susceptible to small changes in the aquatic environment, particularly fluctuations in water temperature and dissolved oxygen (DO) levels. The optimum water temperature for yellow catfish (Pelteobagrus fulvidraco) growth is 26-29 degrees C. However, the culturing process frequently exposes yellow catfish to extreme temperature fluctuations and an insufficient oxygen supply, representing significant challenges to their survival and growth. Therefore, the present study was conducted to investigate the effects of low-oxygen stress on liver metabolism, oxidative stress, and immunity of yellow catfish at various water temperatures by simulating actual aquaculture conditions. The results showed that anaerobic metabolism in liver tissues was increased in yellow catfish from the 26 degrees C-hypoxia grou after prolonged hypoxic exposure compared to the normoxic group (26 degrees C-normoxia group). The activities of hexokinase (HK) and pyruvate kinase (PK) were significantly increased (p < 0.05), suggesting that yellow catfish adapted to the low-oxygen environment by producing metabolites such as lactate for energy. Glycolytic enzyme activities (hexokinase (HK) and phosphofructokinase (PFK)) were altered in the 15 degrees C and 32 degrees C groups under low oxygen conditions. Enrichment analysis showed that differential genes in the liver of yellow catfish were significantly enriched in the nucleotide metabolism, lipid metabolism, and carbohydrate metabolism pathways (p < 0.05), implying that the interactions between temperature and the level of DO may have a significant effect on these pathways. The present study found that the combined stress of water temperature and dissolved oxygen significantly increased the activity of catalase, an antioxidant enzyme, in the liver (p < 0.05). Gene ontology (GO) enrichment analysis revealed that the differentially expressed genes in the livers of all treatment groups were significantly enriched in redox reaction pathways (p < 0.05), suggesting that the oxidative-antioxidative balance of yellow catfish may have been disturbed. Histological results revealed variable degrees of structural damage in both temperature- and low-oxygen-exposed liver tissues. In low oxygen conditions, fluctuations in water temperature significantly increased alkaline phosphatase (AKP) activity in the liver of yellow catfish (p < 0.05). Additionally, differential genes in the ECM-receptor interaction and PPAR signaling or immune-related pathway (p < 0.05) were significantly enriched in the liver, suggesting that the combined temperature and dissolved oxygen effect may weaken or alter the immune system. We hope that this study will provide new insights and data support for research on the culture management and environmental adaptation of yellow catfish, thereby promoting the sustainable development of aquaculture.

This study evaluated the effects of dietary synthetic astaxanthin (SA), Haematococcus pluvialis (HP) and Phaffia rhodozyma (PR) on the growth performance, antioxidant activity, innate immunity, morphology, and pigmentation of juvenile Litopenaeus vannamei. Shrimp (1.15 ± 0.01 g) were fed with the control diet and astaxanthin diets containing 20 mg/kg of astaxanthin from three sources (SA, HP, and PR) for 56 days. The results indicated that, compared with the control group, growth performance was observably elevated in the HP and PR groups (p<0.05). The astaxanthin (SA, HP, and PR) supplemented diets markedly elevated the activities of glutathione peroxidase (GPx) and GST in the intestine and hepatopancreas (p<0.05), while observably reduced the MDA content (p<0.05). The apoptosis rates in three astaxanthin groups were noticeably reduced in comparison with the control group (p<0.05). Dietary astaxanthin (SA, HP, and PR) observably elevated the expression of the Toll, IMD, and CAT genes in the hepatopancreas (p<0.05). Besides, dietary astaxanthin (SA, HP, and PR) noticeably improved the astaxanthin accumulation and pigmentation of shrimp (p<0.05). The survival rates of shrimp challenged with Aeromonas hydrophila were markedly higher in the astaxanthin groups than in the control group (p<0.05), and no significant difference was detected among three astaxanthin groups (p>0.05). Moreover, our results suggested that natural astaxanthin (HP and PR) was more effective for enhancing growth and antioxidant capacity of shrimp. Nevertheless, no marked difference was detected between natural astaxanthin and SA in coloration performance and disease resistance.

This study evaluated the effects of dietary carbohydrate levels on glycolipid metabolism and liver health of channel catfish. Six isonitrogenous and isolipidic diets with corn starch contents of 10 % (C10), 15 % (C15), 20 % (C20), 25 % (C25), 30 % (C30) and 35 % (C35) were set up. After 8-week feeding trial, there was no significant difference in the growth performance of all groups (P > 0.05). The study showed that C30 and C35 groups significantly increased plasma glucose levels, activated the expression of glycolysis-related genes (gk, hk, pklr, pfk) and mitochondrial oxidative phosphorylation related genes (ndufa1, sdhb, sdha, cytb-c1, cox, atp5fa1, atp5f1b), and repressed the expression of gluconeogenesis-related genes (pc, fbp, pepck, g6p) in the channel catfish (P < 0.05). The upregulation of glycogen synthesis-related genes (ppp1r3g, ppp1r3c, ppp1r3b, gys, gnl, ugp2a, ugp2b) contributed to a significant increase in hepatic glycogen content. In addition, C30 and C35 groups significantly increased the expression of pentose phosphate pathway related genes (g6pd, 6gpd), while C10 to C25 groups glucose metabolism-related pathways did not exhibit significant differences. Hepatic triglyceride and cholesterol results showed that C30 and C35 groups induced excessive lipogenesis, activated the expression of lipogenesis-related genes (acc, acly, vldlr) and cholesterol synthesis-related genes (srebf2, hmgcr, sqle). In C30 and C35 groups also increased the hepatic ALT, AST and MDA levels, activated the expression of injury-related genes (a-sma, tgf-β), inflammation-related genes (tnf-α, il-1β, il-6) and apoptosis-related genes (baxb, caspase-3, caspase −10) (P < 0.05). C35 group significantly further increased the expression levels of stress genes such as hamp, hsp70 and hsp90 (P < 0.05), while there were no significant differences in the levels of lactate and cortisol in all groups (P > 0.05). In conclusion, our results suggest that dietary carbohydrate levels less than 30 % will not impair the health and growth performance of the channel catfish.

Light quality plays a crucial role in biomass production, biochemical composition, and nutrient removal efficiency in microalgae-based wastewater treatment systems. However, its effects in organic aquaculture wastewater systems remain underexplored. This study investigated the responses of Chlorella sorokiniana CMBB276 to six light qualities (red, blue, white, mixed, red-to-blue, and red-to-mixed) in a system where dissolved organic nitrogen (DON) and phosphorus (DOP) accounted for 83.50 % of total nitrogen and 88.30 % of total phosphorus, respectively. Among the treatments, red light produced the highest biomass (1.54 g L-1), significantly exceeding the biomass achieved under blue light, which yielded the lowest value (0.61 g L-1) on day 16-only 40 % of the yield observed under red light. Additionally, organic matter removal efficiency followed the hierarchy: red light/red-to-mixed/red-to-blue > mixed light > blue light > white light. Across all light treatments, dissolved organic matter (DOM) transformation involved reduced tyrosine-like substances (C1) and increased humic-like substances (C2, C4), with variations in organic matter degradation and growth dynamics. In terms of biochemical composition, protein accumulation was highest under blue light at 30.10 % dry weight (DW), while carbohydrate content peaked under red-inclusive lights, reaching 52.41 % DW under red-to-blue light. These findings demonstrate the potential of C. sorokiniana for nutrient removal and biomass production in aquaculture wastewater, providing insights for optimizing sustainable aquaculture practices.

High carbohydrate diet (HCD) has been shown to disrupt hepatic glycolipid metabolism and contribute to the development of metabolic dysfunction-associated steatotic liver disease (MASLD). However, effective therapeutic strategies targeting the underlying pathological mechanisms remain limited. Here, we designed a series of feeding experiments to evaluate the effects of dietary c-SRC inhibitor (UM-164) on glycolipid metabolism and liver health in channel catfish (Ictalurus punctatus) fed HCD. The experimental design consisted of three isonitrogenous and isolipidic diets: CON (18 % corn starch), HCD (36 % corn starch), and HCS (36 % corn starch; 20 mg/kg UM-164). Juvenile channel catfish (7.63 +/- 0.02 g) were fed with these diets for 8 weeks. Our results revealed that the HCS treatment mitigated the HCD-induced increases in hyperglycemia, hyperlipidemia and glycosylated hemoglobin (GHb). HCS reduced the HCD-induced upregulation of pentose phosphate pathway (PPP)-related genes (c-src, g6pd and 6pgd), NADPH levels and glycolytic genes (hk1, gk, pfkla, pfklb and pk). HCS reduced liver glycogen content by inhibiting the expression of PPP1R3G. HCS attenuated the HCD-induced activation of mTOR, leading to reduced expression of key lipid synthesis factors (SREBPs), as confirmed in vivo and vitro experiments. HCD resulted in a significant elevation of liver health indicators (ALT and AST), and UM-164 alleviated the HCD-induced liver damage. In conclusion, UM-164 reduced HCD-induced hepatic lipid accumulation by inhibiting PPP and mTOR-SREBPs signaling, thereby improving liver health. These findings suggest that UM-164 is a promising therapeutic agent for protecting liver health and may provide a viable basis for the treatment of MASLD.

In order to investigate the effect of sodium bicarbonate(NaHCO3)on intestinal damage in largemouth bass(Micropterus salmoides)under chronic high-temperature stress,juvenile largemouth bass(20.26±0.08)g were fed diets with or without sodium bicarbonate(NaHCO3,5 g/kg)for 8 weeks.The results showed that there was no significant difference in the specific growth rate in the NaHCO3 group compared to the control group at chronic high temperatures.However,the NaHCO3 group exhibited significantly improved feed efficiency,protein deposition rate,and protein effi-ciency,along with a marked increase in intestinal amylase and trypsin activities.The addition of NaHCO3 also signifi-cantly enhanced the intestinal total antioxidant capacity(T-AOC),catalase(CAT),superoxide dismutase(SOD),and glutathione peroxidase(GPx)activities.Furthermore,NaHCO3 up-regulated the expression of cat and gpx1a genes and down-regulated the gene expression of keap1.Meanwhile,the expressions of pro-inflammatory cytokines(il-1β,tnfα,and il15)were significantly down-regulated in the group,while the expression of anti-inflammatory cytokine il10 was up-regulated.In addition,the expression of hsp90,hsp70,and hsp60 genes in the intestines of largemouth bass in the NaHCO3 group was significantly lower than that in the control group.Histologic analysis of the intestinal tract showed that high-temperature stress induced intestinal damage in largemouth bass,and the addition of NaHCO3 significantly improved the intestinal tissue morphology and up-regulated the expression of intestinal zo1,jam,occludin,and muc2.In conclusion,the addition of 5 g/kg NaHCO3 to the feed effectively alleviated chronic high-temperature stress-induced intestinal damage in largemouth bass by improving intestinal antioxidant capacity,intestinal inflammation,and intesti-nal barrier function.These findings may provide a new perspective to improve the intestinal health of fish under high-temperature stress.

This study aimed to evaluate the effects of dietary carbohydrate and protein levels on growth performance, nutrient metabolism, liver function and flesh quality of channel catfish (Ictarulus punctatus). Four experimental diets were designed containing 20 % or 32 % carbohydrate with 32 % or 36 % protein, respectively (C20P32, C20P36, C32P32 and C32P36) and fed to triplicated groups of channel catfish (initial body weight: 60.88 +/- 0.42 g) for 8 weeks. A two-way ANOVA revealed significant interactions between dietary carbohydrate and protein levels, influencing growth performance, VSI, LRE, body composition (lipid, moisture and ash), plasma metabolites (T-CHO, TG, HDL-C and LDL-C), liver T-CHO level and g6pase mRNA expression. Higher dietary carbohydrate increased FE, IPF, CF and PER, whereas higher protein level reduced PRE and PER. High carbohydrate intake promoted hepatic glucose transport (glut2), glycolysis (gk, pfkl, pkl), glycogenesis (gys2), glycogenolysis (pygl) and lipogenesis (TG content, Oil Red O area, expression of acaca, srebp1, fasn and scd). Concurrently, it suppressed lipolysis (lpl, perilipin, cpt-1a, aco and ppar alpha), resulting in increased glycogen and lipid accumulation in the liver. Moreover, high carbohydrate decreased AST activities and up-regulated the expression of protein synthesis genes (mtor, s6k1 and s6) in liver. Notably, there were no significant differences in plasma ALT, AST and AKP levels, liver ROS and MDA contents as well as the expressions levels of liver inflammatory cytokines (tgf beta, tnf alpha, il6 and il1 beta) among the groups. In terms of white muscle, dietary carbohydrate and protein levels interacted to affect lipid content, the expression levels of genes involved in lipid and glycogen metabolism, mrf4 expression level, fatty acid profiles (EPA, DHA, n-3 PUFA and PUFA) and texture properties (flexibility, adhesiveness and stringiness). Furthermore, high carbohydrate increased muscle glycogen, lactate and LDH contents, while decreased water holding capacity and myf5 expression level in muscle. Higher protein level enhanced the ratio of n-3/n-6 PUFA, myog expression level and fracturability, but reduced toughness in muscle. In conclusion, the addition of carbohydrates to the diet of channel catfish had a protein-sparing effect. Dietary carbohydrate and protein levels didn't affect liver function, while induced several modifications on flesh quality in channel catfish.

This study was carried out to search for the protein requirement of a new strain of preponderant amphitriploid Carassius clone, which integrated genomes partly from white crucian carp (C. auratus cuvieri). Seven groups of fish (body weight: 9.73 ± 0.03 g) were fed with seven isolipidic and isocarbohydrate diets containing 21.38%, 25.82%, 27.94%, 31.36%, 34.23%, 37.87%, and 40.70% crude protein (P21, P24, P27, P30, P33, P36, and P39), respectively. After 8-week feeding, weight gain rate (WGR) and specific growth rate (SGR) were lower in the P30 group than those in the P39 group, but no difference was found in final body weight (FBW), survival, condition factor (CF), or hepatosomatic index (HSI) between different groups. Increased dietary protein decreased feeding rate (FR) and viscerosomatic index (VSI) while improved feed efficiency (FE). Decreased protein retention efficiency (PRE) and improved activity of liver alanine aminotransferase (ALT) and content of plasma ammonia suggested intensified fish amino acid catabolism in high dietary protein groups. The dietary protein requirement of the new Carassius clone was as low as 21.38% for growth. The optimal dietary protein for high FE was 39.62% and should be less than 30.56% to maintain the maximum protein retention. High dietary protein might be harmful to the fish due to the increased contents of liver malondialdehyde (MDA) and plasma cortisol. Dietary protein level altered fish body and muscle flavor substance composition. Low dietary protein could obtain high muscle fatty acid, free amino acid, and lipid accumulation, including whole body and muscle crude lipid, plasma total triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-c), and low-density lipoprotein cholesterol (LDL-c). Therefore, the recommended dietary protein for this new Carassius clone juvenile should be 21.38%-30.56%.