Fish Physiology and Biochemistry最新文献

This study investigated the prophylactic effects of dietary supplementation with Azadirachta indica (neem) and Moringa oleifera (drumstick) bark against aluminum toxicity in juvenile Labeo rohita. The 60-day experiment consisted of a 45-day pre-exposure supplementation period followed by a 15-day aluminum challenge. Fish (initial weight, 12.5 ± 1.8 g) were randomly distributed into five treatment groups: a control without aluminum exposure, a control with aluminum exposure, and three experimental groups exposed to aluminum while receiving diets supplemented with either neem bark powder (1% w/w), Moringa bark powder (1% w/w), or their combination (1:1 ratio, 1% w/w). Fish were sampled on days 0, 15, 30, and 45 during pre-exposure and on days 7 and 15 during aluminum exposure (8.56 mg/L). Combined bark supplementation demonstrated superior protective effects during aluminum exposure, maintaining significantly higher specific growth rate (2.15 ± 0.12%) compared to the aluminum-exposed control (1.12 ± 0.15%). The combined treatment also preserved hemoglobin levels (7.8 ± 0.4 g/dL vs. 5.2 ± 0.4 g/dL in the aluminum-exposed control) and antioxidant enzyme activities, with superoxide dismutase maintaining near-normal levels (38.6 ± 2.1 U/mg protein vs. 15.2 ± 1.8 U/mg protein in the aluminum-exposed control) at day 15 of exposure. Combined bark treatment significantly reduced aluminum accumulation in gill (118.4 ± 10.2 µg/g vs. 245.6 ± 18.4 µg/g), liver (75.6 ± 8.4 µg/g vs. 158.2 ± 12.6 µg/g), and muscle (20.4 ± 3.2 µg/g vs. 42.5 ± 4.8 µg/g) compared to the aluminum-exposed control. These findings demonstrate that prophylactic dietary supplementation with combined neem and Moringa bark effectively mitigates aluminum toxicity in Labeo rohita by reducing metal bioaccumulation, preserving antioxidant defenses, and maintaining growth performance, offering a practical and sustainable strategy for protecting cultured fish in aluminum-contaminated aquaculture systems .

This study evaluated the protective effects of fermented Chinese herbal on manganese (Mn)-induced oxidative stress and pathological damage in the intestines of largemouth bass (Micropterus salmoides). The experiment consisted of two treatments: the Mn exposure treatment and the manganese plus fermented Chinese herbal (Mn + FCHM) treatment. In the Mn exposure treatment, fish were exposed to Mn solutions at concentrations of 0, 0.750, 1.125, and 1.688 mg/L, while being fed a basal diet. In the Mn + FCHM treatment, fish were exposed to the same Mn concentrations but were fed a fermented Chinese herbal diet. Each group had three replicates, with 30 fish per replicate, for a duration of 60 days. The results showed that the growth performance of the largemouth bass in the Mn exposure treatment significantly decreased, with structural damage and oxidative stress observed in the intestines (P < 0.05). In the Mn + FCHM treatment, the WGR, SGR, and CF of largemouth bass significantly increased, while VSI and FCR significantly decreased (P < 0.05); The intestinal villi were relatively intact, the Mn deposition in the intestines decreased, and the intestinal damage was significantly improved; The expression levels of intestinal barrier genes Occludin-1, Claudin, and ZO-1 were significantly increased (P < 0.05); The activities of GSH-PX, T-AOC, CAT, and SOD enzymes were significantly enhanced, and the MDA content significantly decreased (P < 0.05); The gene expression levels of GSH-PX, CAT, and SOD were significantly increased (P < 0.05). This study demonstrates that fermented Chinese herbal is effective in mitigating oxidative stress and pathological injuries in the intestines of largemouth bass (Micropterus salmoides) caused by heavy metal manganese (Mn), thereby promoting intestinal health.

This research aimed to explore how different levels of dietary lipids and lecithin influenced the antioxidant capacity, inflammatory response, and fibrotic damage in the kidney tissues of blunt snout bream (Megalobrama amblycephala). The five experimental diets were formulated to include the control (5.49% lipid), lecithin diet (5.63% lipid, 0.10% lecithin), high-fat diet (HFD, 11.80% lipid without additional lecithin), HFD + 0.10% lecithin (11.69% lipid + 0.10% lecithin) and HFD + 0.20% lecithin (11.41% lipid + 0.20% lecithin). The blunt snout bream was reared on these diets for 12 weeks. Lecithin lessened kidney damage and weight loss caused by an HFD. Lecithin mitigated the reduction in the activities of antioxidant enzymes, including T-AOC, GSH-Px, T-SOD, and CAT. It also alleviated the decrease in the mRNA expression of antioxidant-related genes such as sod1, gpx1, cat, nrf2, and ho-1, as well as the protein expression of Nrf2. Moreover, it counteracted the up-regulation of MDA content, the mRNA expression of the antioxidant-related gene keap1, and the protein expression of Keap1 caused by HFD. Lecithin addition mitigated the up-regulation of mRNA expression of inflammatory-related genes (tnf-α, mcp-1, nlrp3, il-1β and caspase-3) and proteins (Nlrp3 and Il-1β), serum Il-1β content induced by HFD, and the down-regulation of mRNA expression of inflammatory-related gene il-10. Dietary lecithin addition mitigated the up-regulation of mRNA expression of fibrosis-related genes (tgf-β1, acta-2, actn-4, pdgf, fgfr-2, col1a2 and smad3), serum CRE and BUN content induced by HFD. These findings suggested that dietary lecithin supplementation could significantly improve the growth performance and antioxidant ability of blunt snout bream. It also mitigated inflammatory damage and alleviated kidney fibrosis. As a result, it lessened the adverse impacts of HFD on the functionality and well-being of the kidney tissue in blunt snout bream.

This study was aimed at examining the physiological and biochemical response of live Nile tilapia (NT) (Oreochromis niloticus Linn.) and Nile tilapia blood cells (NTBC) to abrupt ambient temperature reductions. NT was exposed to water temperatures between 24 °C and 14 °C during the experiment, while NTBC was subjected to temperatures between 24 °C and 12 °C, with a 2 °C temperature reduction at each stage. Physiological parameters of NT were assessed, including core body temperature, heart rate, ventilation rate, body coloration score, and oxygen saturation. In addition, biochemical parameters of NTBC were measured, i.e., total antioxidant capacity, hydrogen peroxide, malondialdehyde, nitric oxide, and mitochondrial activity. It was found that lowering the water temperature from 24 °C to 14 °C caused a drop in core body temperature and ventilation rates (P < 0.05), while heart rates rose at 18 °C (P < 0.05) before falling. Body coloration scores became higher at 20 °C and grew more intense as the water temperature fell further (P < 0.05). Mitochondrial activity peaked at 18 °C (P < 0.05), while malondialdehyde rose significantly between 16 °C and 12 °C (P < 0.05). Total antioxidant capacity decreased at 18 °C (P < 0.05) and remained low to 12 °C. Nitric oxide dropped at 20 °C and 12 °C (P < 0.05), while hydrogen peroxide peaked at 14 °C (P < 0.05). These findings indicate that NT is highly sensitive to temperatures below 20 °C, which increases oxidative stress and requires enhanced antioxidant defenses below 18 °C. Finally, the results align between in vivo and in vitro experiments.

As polychaete meal (PM) from Hediste diversicolor has been reported to be a promising alternative to fish meal (FM) and fish oil (FO) in aquafeeds, we hypothesized that replacing FM with PM would support growth performance, feed utilization, and flesh fatty acid profile of European seabass (Dicentrarchus labrax). Therefore, this study was planned to investigate graded PM inclusion levels (0% [control], 5% [PM5], 10% [PM10], 15% [PM15] and 20% [PM20]), selected based on feasible incorporation limits for juvenile European seabass, as a partial substitute for FM (reduced from 29.45% in the control to 14.55 in PM20) in isonitrogenous (48% protein) and isolipidic (14% lipid) diets. A seven-week trial with a total of 150 fish (initial average weight of 14.56 ± 0.01 g) in triplicate tanks assessed growth performance, feed utilization, nutrient digestibility, body composition, fatty acid profiles, and fish-in-fish-out (FIFO) ratio. Growth performance, feed utilization, and organo-somatic indices of experimental fish remained unaffected by dietary PM levels (P > 0.05). A significant linear increase in apparent digestibility coefficients (ADCs) of protein, energy, and organic matter was observed with increasing PM inclusion (P < 0.05), while lipid ADCs remained unaffected P > 0.05). Whole-body protein and lipid content increased, with a corresponding decrease in moisture as dietary PM levels increased (P < 0.05). Fatty acid profiles and lipid quality indices of the liver and fillet were variably affected, liver PUFA levels declined with higher PM, whereas fillet long-chain PUFAs (Lc-PUFAs) such as arachidonic acid (ARA) and eicosapentaenoic acid (EPA) linearly increased. The FIFO ratio fell below 1 at a 20% PM inclusion. The findings suggest that PM can replace up to 50% of dietary FM and partly FO in seabass diets without compromising growth, nutrient utilization, or fillet quality while enhancing sustainability metrics.

The weatherfish Misgurnus fossilis is a freshwater species that adapts to hypoxic conditions during its developmental stage through the presence of external filamentous gills, which serve as primary respiratory organs. Our experimental study aimed to investigate biochemical changes occurring in weatherfish during its development, from ovulated oocytes to larvae with external gills. The concentrations of thyroid hormones were low and relatively stable up to the larval stage at hatching, provided by maternal reserves. However, levels of free triiodothyronine and total thyroxine increased during the larval stage when external gills were present, likely reflecting preparation for their reduction. This indicates that the function of the endogenous self-synthesis thyroid axis begins in weatherfish at a developmental stage preceding larval metamorphosis. Our results indicate that the free fraction of triiodothyronine is more important during fish metamorphosis than its total content, which generally exhibits limited biological activity within the organism. The increase of thyroid levels coincides with an increase in lipid levels; the rise in cholesterol and triglycerides suggests an elevated energy demand essential for metamorphosis. Consequently, thyroid hormone synthesis coupled with lipid mobilization is likely a key predictor of imminent metamorphosis in fish.

Progranulin (PGRN) is a cysteine-rich secreted protein that is expressed in epithelial cells, immune cells, neurons, and adipocytes. It was first identified for its growth factor-like properties and is involved in early embryogenesis and tissue remodelling, acting as an anti-inflammatory molecule. Recently, PGRN was recognized as an adipokine related to obesity and insulin resistance, revealing its metabolic function. In zebrafish, the homologous gene most similar to the human PGRN gene is grna (granulin a). In this study, we used previously obtained grna knockout (KO) zebrafish to investigate the role of grna in obesity resistance and liver development. To explore the role of grna in obesity, grna^-/- zebrafish and wild-type (WT) zebrafish were fed a high-fat diet (HFD) for 2 months. These results indicated that grna^-/- zebrafish were more resistant to HFD-induced obesity than were WT zebrafish. Compared with WT zebrafish, grna^-/- zebrafish presented less visceral fat, abdominal fat, and hepatic fat. In addition, grna^-/- HFD-fed zebrafish presented more severe hepatic vascular fibrosis than WT HFD-fed zebrafish did. During the development of juvenile zebrafish, grna^-/- zebrafish have smaller livers than WT zebrafish do. In conclusion, our findings suggest that grna plays an important role in regulating obesity susceptibility and liver development in zebrafish.

The present study evaluated the pathophysiological and tissue alterations induced by dietary oxytetracycline (OTC) in rainbow trout (Oncorhynchus mykiss). Fish were exposed to three different doses (T₁ = 40 mg OTC/kg body weight, T₂ = 80 mg OTC/kg body weight, T₃ = 120 mg OTC/kg body weight) alongside a control group (T₀) for a period of 30 days. Hematological, immunological, and biochemical parameters were monitored on days 0, 15, and 30 days of OTC exposure. Higher OTC doses caused a significant reduction in total erythrocyte count (TEC), total leucocyte count (TLC), hemoglobin, packed cell volume (PCV), and mean corpuscular hemoglobin concentration (MCHC) while mean corpuscular volume (MCV) levels increased. Dose-dependent reduction was also observed in immune and biochemical markers such as phagocytic activity, NBT, total Ig, protein, albumin, and globulin, but an increase was noticed in the glucose levels in OTC-fed groups. Histological examination revealed liver alterations including sinusoidal dilation, hepatocyte hypertrophy, pyknosis, and congestion, whereas gills showed lamellar fusion, epithelial lifting, and necrosis, with the most severe changes in the T₃ group. SEM analysis confirmed mucus cell proliferation, secondary lamellar thickening, fusion and degeneration. In liver, micro- and macro-steatosis were also evident in OTC-fed groups. Overall, prolonged exposure to high OTC doses markedly compromised physiological integrity, tissue architecture, and immune function, highlighting potential risks to fish health and welfare.

Recent advances in molecular phenotyping have driven the rapid growth of untargeted, multi-dimensional approaches such as epigenomics, transcriptomics, proteomics, and metabolomics. When applied to ecology, these high-throughput omics tools offer powerful new molecular trait descriptors for investigating biological and environmental processes. Using UHPLC-HRMS/MS, we analyzed metabolome variations in gut, liver, and muscle tissues of chubs and gudgeons collected in summer 2019 from French rivers affected by benthic cyanobacterial blooms. Tissue-specific metabolomic profiles were evident, with muscle metabolomes showing the most distinct species differentiation. The different tissue metabolomes of both fish species also varied by sampling location, indicating local environmental influences. Notably, fish from the Vienne site exhibited molecular signatures of metabolic stress, including elevated oxidized glutathione and bile acids, and decreased purines, amino acids, peptides, and lipids-potentially linked to anatoxin-a-producing cyanobacterial mats. These findings underscore the potential of environmental metabolomics as a sensitive tool for assessing ecological stress and support its integration into routine environmental bio-indicator programs.

This study aimed to explore the effect of paeonol (PAE) on growth performance and liver health in largemouth bass (Micropterus salmoides) exposed to cadmium (Cd). Five experimental groups were designed: one control group reared in clean water and fed a basal diet (CONT), alongside four cadmium-exposed groups maintained in 2.75 mg/kg Cd-containing water and fed the basal diet supplemented with 0 mg/kg (Cd), 100 mg/kg (PAE100-Cd), 200 mg/kg (PAE200-Cd), and 400 mg/kg PAE (PAE400-Cd), respectively. The experiment lasted for 56 days. The results showed that Cd exposure significantly inhibited the growth performance of largemouth bass, caused liver dysfunction and pathological tissue damage, led to oxidative stress, inflammatory response, and apoptosis, and induced the expression of the epidermal growth factor receptor (ErbB1)-extracellular signal-regulated kinase (ERK) pathway genes. However, PAE supplementation (200-400 mg/kg) significantly improved the growth performance of largemouth bass. In addition, 200-400 mg/kg PAE reduced the serum levels of hepatic injury biomarkers (AKP, ALT, LDH, and AST) and alleviated histopathological lesions. Furthermore, PAE200-Cd increased the activities of superoxide dismutase (SOD) and catalase (CAT) and reduced malondialdehyde (MDA) levels in the liver. Moreover, PAE200-Cd and PAE400-Cd down-regulated the expression of interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), nuclear factor kappa-B p65 (NF-κB p65), ErbB1, and cellular FBJ osteosarcoma oncogene (C-fos) in the liver. PAE200-Cd significantly increased the expression of cytochrome P450 family 1 subfamily A (CYP1A1) and downregulated the expression of metallothionein (MT) and cysteine-aspartic proteases-9 (Caspase-9). The optimal PAE dose for counteracting waterborne Cd-induced growth impairment and hepatic oxidative stress was 173.37-173.90 mg/kg for largemouth bass.