Fish Physiology and Biochemistry最新文献

Dietary lipids serve as economical energy sources in aquaculture feeds. Elevating lipid content promotes protein conservation and mitigates nitrogen waste. Fish health, however, can be severely impacted by fatty liver resulting from prolonged high-fat diet (HFD) feeding. Adding lecithin to the feed might be a potential improvement solution. This study investigated how dietary lipid and phospholipid levels affect hepatic lipid homeostasis, endoplasmic reticulum (ER) stress, and redox balance in largemouth bass. Five diets were formulated: a control (10.67% lipid, no added lecithin), a normal-lipid diet with 1.0 g/kg lecithin, the HFD (18.65% lipid, no added lecithin), and the HFD supplemented with either 1.0 or 2.0 g/kg lecithin (HFD + lecithin 1, HFD + lecithin 2). Lecithin supplementation reversed HFD-induced intrahepatic fat deposition while mitigating the decline in hepatic polyunsaturated fatty acids content. Lecithin supplementation mitigated HFD-stimulated increases in hepatic triglyceride, total cholesterol, key lipogenic enzyme activities, and mRNA levels of lipogenic genes/transcription factors. Furthermore, lecithin lessened the impact of HFD on hepatic very low density lipoprotein (VLDL), preventing both a lessened VLDL content and diminished VLDL secretion. Regarding ER stress and antioxidant responses: dietary lecithin addition alleviated HFD-induced increment of mRNA levels of ER stress markers and MDA content, and mitigated HFD-induced reduction of hepatic total superoxide dismutase, catalase, and total antioxidant capacity. This demonstrates lecithin's protective role against HFD-induced hepatic injury by restoring lipid homeostasis, alleviating ER stress, and strengthening antioxidant capacity.

A 60-day feeding trial was conducted to evaluate the effects of iron-porphyrin (FePh) supplementation (0, 50, 100, 150, and 200 mg/kg Fe³⁺) compared with 50 mg/kg FeSO₄ in juvenile Epinephelus cyanopodus (16.12 ± 0.15 g). The results demonstrated that FePh at 100 mg/kg maximized the growth performance (P < 0.05), while 50 mg/kg FePh surpassed FeSO₄ in enhancing intestinal barrier integrity and growth. FePh improved systemic iron metabolism by elevating elevated transferrin and hepcidin levels (P < 0.05), with 50 mg/kg FePh significantly increasing hemoglobin and serum iron (P < 0.05). Antioxidant capacity was significantly enhanced (T-AOC and SOD in serum and gills), alongside the upregulation of immune markers (C3, C4, and IgM). FePh also improved intestinal morphology (GC, MP, VL) and intestinal microbiota (P < 0.05). Serum aminotransferase (ALT and AST) levels decreased with elevated activity of antioxidant enzymes. Transcriptomic analysis revealed that FePh suppressed ferroptosis-related genes acsl4 and fth1, while activating iron-regulation genes slc7a11, slc3a2, and hmox1. In conclusion, FePh effectively improved the growth of juvenile E. cyanopodus; enhanced antioxidant capacity, non-specific immunity, and iron metabolism; maintained the stability of the intestinal mucosal barrier to promote intestinal health; and regulated the expression of key genes in the ferroptosis pathway to protect liver health. The optimal FePh inclusion level was 50-100 mg/kg, demonstrating superior efficacy over inorganic iron for sustainable grouper aquaculture.

Nanotechnology has gained significant attention due to its diverse application history, particularly the silver nanoparticles (AgNPs), which are different from other nanomaterials due to their strong and broad-spectrum antimicrobial activity. Therefore, this study developed a sustainable approach for synthesizing AgNPs using vegetable waste extract, characterizing them using Uv-vis spectrometer and scanning electron microscopy (SEM) to confirm spherical, crystalline, and undersized nanoparticles (NPs). In a 30-day dietary exposure trial with Cyprinus carpio, fish fed AgNP-supplemented feed exhibited significant growth retardation, including reduced weight gain, alongside elevated oxidative stress marked by increased catalase (218.51 ± 6.87), superoxide dismutase (243.33 ± 5.82), (430.27 ± 5.39), and (157.68 ± 4.50) activities in gills and brain, respectively at the 6 mg/L. Histopathological analysis revealed severe gill histological alterations i.e., (lamellar fusion, epithelial lifting), muscular degeneration (fiber necrosis, degeneration), and intestinal damage (villus atrophy, lymphocytes infiltration), indicating systemic toxicity. These findings solve two major problems, i.e., environmental cleanness by shifting vegetable residue into fine particles and a potential aquatic toxicity.

Sulfamethoxazole (SMZ), a sulfonamide antibiotic widely used in aquaculture, and its metabolites are released into the environment, becoming a potential threat to the health of hydrobionts. Lycopene (LYC), a potent antioxidant, was studied and found to possess anti-inflammatory and anti-oxidative stress pharmacological activities. This study aims to explore the potential protective effect of LYC on SMZ-induced gill injury in grass carp and its mechanism. The grass carp were exposed to 0.3 μg/L SMZ and 10 mg/kg body weight of LYC for 30 days. Fish gills were collected for examination of microstructure, oxidative stress indicators, and expression of related proteins. Our study found that SMZ exposure caused oxidative stress in fish gill tissues, with microstructural alterations. Meanwhile, relevant indicators of inflammation, such as IL-1β and NF-κB, were significantly up-regulated compared with the Con group, creating an inflammatory environment in vivo. In addition, SMZ also activated ER stress-related proteins and autophagy marker proteins. The above toxic effects were significantly alleviated after LYC intervention, and the mechanism involved LYC activating the Nrf2 pathway by binding to Keap1, upregulating HO-1 and NQO1 to enhance antioxidant capacity, and inhibiting NF-κB-induced inflammatory response. In conclusion, our study demonstrated that LYC as a dietary supplement could alleviate SMZ-induced damage in fish gills, and this natural antioxidant is expected to be developed into an effective drug to reduce the harm caused by SMZ in aquaculture.

Teleost species display a diverse range of reproductive strategies, consisting mainly of gonochorism and hermaphroditism, either sequentially or simultaneously. This leads to species-specific sex determination processes. Owing to the vast range of teleost species, sex determination and differentiation mechanisms vary in their sexual patterns; therefore, sexual plasticity in gonadal development is inevitable. Under certain environmental conditions, such as fluctuations in temperature, pH, density, social interaction, and hypoxia, gonadal fate is liable to change through a phenomenon referred to as gonadal transdifferentiation. This is a reprogrammable mechanism that can occur either naturally or be induced artificially in certain species at various life stages. Transdifferentiation results from the differential expression of steroidogenic enzyme genes or transcription factors that confer phenotypic, molecular, or morphological changes, such as sexual dimorphism. In addition, many endocrine disruptors manipulate the endocrine system of various fish species by interfering with their genetic pathways or with the profiles of endogenous steroid hormones, causing a shift in the sex ratio of a given population. In the current modern chemical environment that includes endocrine disrupting chemicals, fish can undergo gonadal transdifferentiation, which can lead to functional sex reversal. This review summarizes gonadal transdifferentiation and provides evidence of diverse strategies found in teleosts, from molecular-level changes to feminization or masculinization of gonads to sex reversal, induced either naturally or unnaturally. We end with a discussion of the adverse effects of endocrine disruptors and summarize areas for future research.

The green guapote Mayaheros beani is a fish of northwestern Mexico with importance as an edible and ornamental fish; however, there are still information gaps related to the physiological response of these fish under different environmental conditions. Therefore, the present study focused on studying the productive performance, proximal composition, blood biochemistry, and digestive capacity of juvenile M. beani (initial body weight: 2.56 ± 0.31 g) cultured at 0, 10, 20, and 30 practical salt units (PSU) (S0, S10, S20, and S30, respectively). After 8 weeks of testing, the weight gain (3.89 ± 0.35 g) and specific growth rate (1.68 ± 0.05 g/day) of the fish who received treatment S10 were significantly greater than those who received the other treatments. The best responses for feed conversion ratio and protein efficiency ratio were observed in those fish grown in salinities ≤ 10 PSU. Proximate analysis of the whole body revealed significant differences in dry matter content and total lipids between treatment S20 and S0, being higher in S0. Then, the highest levels of total protein (3.20 g/dL), globulin (1.77 g/dL), and cholesterol (348 mg/dL) in blood serum were recorded in fish grown in freshwater. Organisms subjected to the highest salinity (S30) had the highest values of proteases (243.7 U/mg), lipases (0.80 U/mg), and α-amylases (26.49 mU/mg) compared with levels of these enzymes recorded in fish at S0. These findings suggest culturing juvenile M. beani at salinities ≤ 10 PSU to avoid negatively affecting the growth, food use, or health of these organisms.

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.