Fish Physiology and Biochemistry最新文献

Fish are particularly vulnerable to microplastics (MPs), especially polypropylene microplastics (PP-MPs), which are widely used and environmentally persistent. Despite their prevalence, little is known about their impact on fish immune systems. Thus, this study's goal was to look at the antioxidants, immunotoxicological, and histopathological impact of PP-MPs on African catfish Clarias gariepinus and the ameliorating role of Spirulina and recovery. A total of 108 fish, weighing 125 ± 3 g and 27 ± 2 cm, were acclimated and divided into six experimental groups (in triplicate): control, PP-MPs-treated groups (0.14 and 0.28 mg/L), PP-MPs + Spirulina (200 mg/L), and Spirulina alone. Fish were exposed to treatments for 15 days, followed by a 45-day recovery period. Antioxidant enzymes (SOD, CAT, GST, MAD), immune biomarkers, and histopathological changes in the spleen and head kidney were assessed. PP-MPs exposure led to a significant (p < .05) decline in antioxidant enzymes and immune biomarkers compared to controls, with increased melanomacrophage centers and tissue damage. Spirulina supplementation significantly improved immune and antioxidant responses, although some parameters, like MAD and histopathological alterations, showed incomplete recovery even after 45 days. PP-MPs have immunotoxic and oxidative effects on Clarias gariepinus, with partial recovery possible through Spirulina supplementation. However, full restoration of immune tissue morphology requires longer recovery periods. The observed immune alterations were closely associated with histopathological damage in key immune organs.

Exemestane is an aromatase inhibitor that is used for the treatment of breast cancer. The aim of this study was to evaluate the effects of exemestane on liver development of zebrafish embryos. In this study, zebrafish embryos at 72 h post-fertilization (hpf) were exposed to varying concentrations (1, 2, and 3 mg/L) of exemestane for 72 h (until 144 hpf). The results demonstrated that exemestane exposure significantly reduced liver area and expanded the yolk sac in a dose-dependent manner, accompanied by progressive lipid accumulation. At the highest concentration (3 mg/L), exemestane markedly downregulated the expression of key liver development markers, including fatty acid-binding protein (fabp10a) and ceruloplasmin (cp). The study further revealed that exemestane exposure at 2 mg/L and 3 mg/L significantly increased reactive oxygen species (ROS) levels while decreasing the activities of antioxidant enzymes, specifically catalase (CAT) and superoxide dismutase (SOD). Interestingly, higher concentrations of exemestane resulted in reduced levels of the lipid peroxidation product malondialdehyde (MDA) and decreased mitochondrial numbers. Additionally, exemestane treatment altered the expression of genes related to sugar and lipid metabolism and upregulated pro-apoptotic genes, including bax, p53, and caspase 3, in zebrafish embryos. A crucial finding was that p53 knockdown in zebrafish embryos effectively mitigated the hepatotoxic effects induced by exemestane. These collective results indicate that exemestane induces hepatotoxicity in zebrafish primarily through activation of the p53 signaling pathway. This study provides valuable insights into the potential hepatotoxic effects of exemestane, offering important references for its clinical safety evaluation.

This study investigated the effects of MS-222 on biochemical indices, antioxidant status, nonspecific immune responses, histomorphology (gill and liver), gut microbiota, and flesh quality in largemouth bass (Micropterus salmoides). The anesthetic effects of MS-222 at concentrations of 20, 40, 60, 80, and 100 mg/L were first evaluated in fish (~ 468.34 g). Deep sedation was achieved at 40 mg/L, which was identified as suitable for live transportation. Fish were then exposed to 40 mg/L MS-222 for 24 h and transferred to clean water for recovery. Serum, gill, liver, intestine, and dorsal muscle samples were collected at 6, 12, and 24 h during exposure and at the same intervals post-recovery. Serum cortisol, glucose, LDH, and AST levels did not change significantly during sedation or recovery, although BUN levels increased significantly. Antioxidant enzyme activities were not significantly affected, whereas malondialdehyde (MDA) decreased during sedation. MS-222 caused atrophy and hypertrophy of gill filaments, reduced nucleoli, and increased vacuolation in hepatopancreas cells; these changes were not fully reversed after 24 h of recovery. Gut microbial composition was altered, with a reduction in beneficial genera such as Cetobacterium. Flavor-related compounds, including sweet and umami amino acids, betaine, and nucleotides, increased during sedation and recovery. MS-222 also decreased the proportion of monounsaturated fatty acids (MUFAs) and increased polyunsaturated fatty acids (PUFAs). Electronic nose analysis showed distinct changes in muscle flavor during sedation, which diminished during recovery. Overall, MS-222 at 40 mg/L significantly influenced the physiology, biochemistry, and flesh quality of largemouth bass, providing a reference for its application in live transportation.

ECE1 is involved in the development of the lamprey embryonic heart. Endothelin converting enzyme 1 (ECE1) is a key enzyme for the production of endothelin, which, as a potent vasoconstrictor, plays a central role in regulating the growth and differentiation of cardiomyocytes and smooth muscle cells. The enzyme is widely expressed in human tissues and is significantly upregulated in a variety of cancers, with a key impact on the development and invasiveness of cancer. In addition, ECE1 is also involved in the development of neural crest cell-derived organs such as the heart. In vertebrates, jawed animals (such as mammals) mainly express ECE1, ECE1L, and ECE2 genes, but the function of ECE genes in jawless animals (such as the lamprey) has not yet been clarified. In this study, the ECE1 gene was cloned from the Lethenteron reissneri, and bioinformatics analysis showed that it had a high degree of similarity with the ECE1 of jawed vertebrates. This discovery provides important clues for exploring the role of ECE1 in lamprey biology, especially its potential functions in signal transduction, nervous system, cardiovascular system, digestive system, and immune diseases.

Degeneration of dopaminergic neurons is associated with several neurological and psychiatric disorders, including Parkinson's disease, schizophrenia, and Huntington's disease. To find new therapies for these conditions, animal models based on exposure to toxins, such as paraquat (Pq) or 6-hydroxydopamine (6-OHDA), have been developed. Purinergic signaling has emerged as a key factor in motor illness. This study evaluated the influence of Pq and 6-OHDA on ATP metabolism and gene expression of nucleotide- and nucleoside-metabolizing enzymes in zebrafish brain. Adult zebrafish were injected i.p. with saline or Pq (10 or 20 mg/kg) at two-day intervals for a total of six doses. For 6-OHDA treatment, zebrafish received one i.p. injection of saline or 6-OHDA (25 or 50 mg/kg). Six days after the 6-OHDA treatment or 6 i.p injections of Pq, ATP metabolism and gene expression assays were evaluated in zebrafish brain. A decrease in extracellular adenosine (ADO) catabolism was observed in Pq-treated animals compared to the controls. In 6-OHDA-treated fish, there were no changes in ATP levels; however, ADP levels were altered and AMP levels decreased at both doses tested. Meanwhile, ADO levels increased compared to the control. Both treatments led to increased extracellular inosine (INO) levels. Changes in adenosine deaminase gene expression were observed following 6-OHDA exposure. Given the observed alterations in ATP and adenosine catabolism, purinergic signaling emerges as a regulatory mechanism that could be targeted in the development of therapeutic strategies aimed at mitigating neurotoxic damage and preserving neuronal function.

Functional feeds designed to enhance the host's immune response and improve disease resistance are among the most popular strategies to mitigate the impact of infectious diseases and abiotic stressors in aquaculture. While reviewing the current scientific literature on this issue, we have detected that there is a need to standardize the evaluation criteria for feed additives with immunostimulant properties in terms of the duration of the trial and selection of key end-points related to the expected effect of the dietary intervention. The evaluation of the disease protective role of a feed additive should not be based only on end-points from cellular and immune biomarkers, but it should also be complemented with end-points based on survival data of specimens exposed to an in vivo infective challenge. We also recommend giving special consideration to the basal diet used in these studies since the inclusion of certain ingredients may have confounding results with those expected from the additive or functional ingredient of interest. Regardless of the in vivo challenge model selected (balneation, cohabitation, intraperitoneal injection, or oral/anal intubation), abiotic factors such as temperature, water flow, light, and water quality strongly influence the development of disease and must be also taken into consideration when designing experimental challenge models. Thus, it is of paramount importance to standardize the studies testing the efficacy of functional diets designed to protect the host from infectious agents and to assist in harmonizing the interpretation of their results.

Optimization of larval feed is a prerequisite for the successful ontogeny of fish larvae. A feeding trial of 35 days was conducted in a replica of five (500 larvae per tank/2500 per group), to determine the dietary protein requirements of rohu Labeo rohita larvae. Four experimental nano-particulate diets (P45, P50, P55, P60) having 45, 50, 55, and 60% CP were prepared and fed to L. rohita larvae from 3 to 35 DAH (days after hatching). Sampling for growth assessment, digestive enzymes, and gene expression study was done on 3, 10, 15, 20, 25, 30, and 35 DAH. Among all the diets, P55 followed by P60 showed the most significant positive effect on growth (NWG, SGR) and survival of fish larvae. Amylase did not show any significant change among the experimental groups; however, total protease, trypsin, and chymotrypsin showed significantly high activity in P55, followed by P60, and the least activity in P45. Moreover, a positive correlation was observed between age DAH and GH and IGF-1 in all groups, while a negative correlation was observed with myogenic-regulating factors MRFs, i.e., MyoD and MYF-5. The significantly higher expression of GH and IGF-1, and a sustained higher expression of MRFs in P55 among all the studied groups, indicate 55%CP as the optimum dietary protein requirement for L. rohita larvae.

Aeromonas hydrophila is a highly virulent pathogen that causes substantial mortality in Labeo rohita fingerlings. In our present study, phytochemical analysis of curry leaf (Murraya koenigii) confirmed the presence of bioactive compounds such as alkaloids, phenolics, flavonoids, and terpenoids, known for their potent antimicrobial and immunomodulatory properties. This study evaluates the immunomodulatory and haemato-protective effects of curry leaf (Murraya koenigii) ethanolic extract (CLEE) against Aeromonas hydrophila infection in Labeo rohita, focusing on haematological, biochemical, and immunological parameters. In infection trials, survival rates were higher for feeds treated with 1 g, 2 g, and 3 g of CLEE were 46.67%, 68.89%, and 66.67%, respectively, compared to 36.67% in the bacterial control group. Haematological results showed a significant dose-dependent increase in red blood cell (RBC) count, haemoglobin, and white blood cell (WBC) count. The CLEE 2 g and CLEE 3 g groups had significantly (P < 0.05) higher RBC counts of 1.08 ± 0.01^a × 10¹²/L and 0.99 ± 0.07^a × 10¹²/L, compared to 0.49 ± 0.09^c × 10¹²/L in the bacterial control. Biochemical analysis revealed significant (P < 0.05) reductions in serum glucose, total protein, and liver enzymes (SGOT, SGPT, ALP). Specifically, serum glucose levels significantly (P < 0.05) decreased from 99.93 ± 3.04^a mg/dL in the bacterial control to 75.52 ± 1.68^d mg/dL in the CLEE 2 g and 79.89 ± 1.86^c mg/dL in the CLEE 3 g. Antioxidant enzyme activities, including superoxide dismutase (SOD), catalase, and myeloperoxidase activity (MPO), were significantly (P < 0.05) higher in CLEE-treated groups. Histopathological analysis showed partial regeneration of liver and kidney tissues, especially in the CLEE 2 g and CLEE 3 g groups. These findings suggest that CLEE effectively mitigates A. hydrophila infection, improves immune function, reduces oxidative stress, and promotes tissue recovery in L. rohita fingerlings. This study addresses a significant research gap, offering insights into CLEE's potential applications in aquaculture and its therapeutic efficacy in combating bacterial infections.

Aquaculture is a crucial sector in the global food system, significantly contributing to the supply of nutritious food and creating economic opportunities. This review article examines the essential role of vitamins in fish farming, highlighting their contributions to growth performance, immune function, antioxidant activity, digestive efficiency, disease resistance, and overall body composition. Vitamins are not only vital nutrients for the growth and metabolic functions of aquatic organisms but also serve as essential cofactors in numerous biochemical reactions, thereby promoting fish health and development. Recent innovations in aquafeed formulations and vitamin nutrition have led to a reassessment of the dietary vitamin needs for various farmed fish species. This review synthesizes contemporary research in fish nutrition, demonstrating the substantial effects of vitamins on growth rates (up to 20%), immune response enhancement (up to 40%), optimization of digestive and hepatic enzyme activities, and improvement of biochemical and hematological parameters. The magnitude of these benefits is influenced by factors such as vitamin type, fish species, age, and environmental conditions. Additionally, the review highlights the significance of vitamins in enhancing disease resistance and improving body composition in aquaculture species. The insights provided aim to guide aquaculture professionals and researchers in recognizing the critical role of vitamins in fostering sustainable fish farming practices. Future research in fish nutrition should prioritize the development of sustainable vitamin supplementation strategies, including the exploration of plant-based and microbial vitamin sources, the optimization of nutrient delivery methods, and the reduction of environmental impacts. By focusing on these areas, we can enhance fish health, improve feed efficiency, and promote more environmentally sustainable aquaculture practices.

The olive flounder (Paralichthys olivaceus) is an economically important species in South Korea. However, the specific dietary requirement for tryptophan (Trp) has not been determined for this species at any growth stage. Thus, this study aimed to determine the dietary Trp requirement for juvenile olive flounder under low water temperature conditions. Two consecutive feeding trials were conducted, each using diets with different concentrations of dietary Trp: Exp-Ⅰ (0.39-14.46 g kg^-1) and Exp-Ⅱ (0.93-6.96 g kg^-1). The initial mean body weights of the olive flounder were 4.38 ± 0.03 g (Exp-Ⅰ) and 18.4 ± 0.1 g (Exp-Ⅱ). In Exp-Ⅰ and Exp-Ⅱ, fish were randomly distributed into 18 tanks (120 L), corresponding to six dietary groups with three replicates per group (30 fish per tank). Fish were fed the experimental diets for 13 weeks (Exp-Ⅰ) and 8 weeks (Exp-Ⅱ). The water temperatures during the trials were 18.2 ± 2.4 ℃ in Exp-Ⅰ and 17.5 ± 2.8 ℃ in Exp-Ⅱ, representing suboptimal thermal conditions. The results indicate dietary Trp concentration significantly affected the growth and survival of the fish. In particular, the lowest growth and survival were observed in fish fed the diet with the lowest concentration of Trp in both feeding trials. Additionally, the fish fed the Trp-deficient diet (0.39 g kg^-1) exhibited lower levels of hematological parameters, immunity, antioxidant capacity and whole-body crude protein compared to Trp supplemented groups (2.33-14.46 g kg^-1). In fish fed a Trp-deficient diet (0.39 g kg^-1), expression of tight junction proteins was down-regulated, abnormal development of mucosal folds was observed, and intestinal inflammatory cytokines were upregulated compared to Trp supplemented groups (2.33-14.46 g kg^-1). Fish fed Trp-supplemented diets showed significantly higher plasma levels of Trp, serotonin, melatonin and cortisol compared to those fed the Trp-deficient diet. The dietary Trp concentration required for fish growth was estimated to be 3.08 g kg^-1 (6.06 g kg^-1 of protein) in the juvenile stage (Exp-Ⅰ) and 2.17 g kg^-1 (4.27 g kg^-1 of protein) in the post-juvenile stage (Exp-Ⅱ), respectively, as determined by broken-line regression based on final body weight.