Search Results (826)

This study evaluated the impact of Bacillus subtilis supplementation on growth, antioxidant status, digestive enzyme activities, hematological parameters, blood biochemistry, and immune responses in Nile tilapia (Oreochromis niloticus) fingerlings. A total of 180 fingerlings (mean weight: 5 ± 0.5 g) were randomly assigned to four groups: a control group and three probiotic-supplemented groups with 10⁶ (S-1), 10⁸ (S-2), and 10¹⁰ (S-3) CFU g⁻¹ of B. subtilis, following a completely randomized design. Fish were fed twice daily for eight weeks. Results showed that the 10¹⁰ CFU g⁻¹ group exhibited significantly higher weight gain (43 g), specific growth rate (2.5%/day), and better feed conversion ratio (0.7) compared to the control (30 g, 2.2%/day, and 1.4, respectively). Hematological parameters (WBC, RBC, hemoglobin) and immune responses (phagocytic activity, lysozyme) were significantly improved. Blood biochemistry showed decreased ALT/AST levels and increased ALP activity. Digestive enzymes (protease, lipase, amylase) and antioxidant activity (GPx, CAT, SOD) were enhanced, with reduced MDA levels. No significant differences were observed in survival rates or stress responses. These findings suggest that B. subtilis supplementation at 10¹⁰ CFU g⁻¹ improves growth, immune function, and antioxidant status, making it a promising probiotic for Nile tilapia. Full article

The high-input production mode of rice monoculture (RM) has caused severe soil degradation and biodiversity loss, necessitating a transition toward more sustainable practices. The traditional rice-fish co-culture (RF) may provide valuable insights for this situation. However, it remains elusive how long-term RF system influences soil microbial community structure, enzyme activities, and carbon (C) sequestration. Here, a study was conducted at two representative RF areas in Lianshan Zhuang and Yao Autonomous County. At Shatian (P1), three treatments included rice monoculture (RM1) and 2-year and 5-year RF (RF2, RF5). At Gaoliao (P2), the experimental treatments included rice monoculture (RM2) and 15 and 30 years of RF (RF15, RF30). We collected the surface layer (0–20 cm) soils. Then, we analyzed the chemical properties, phospholipid fatty acids (PLFA), and enzyme activities to investigate the effects of their variation on soil C sequestration. The results showed that RF treatments significantly increased soil organic C (SOC) content. Specifically, RF2 and RF5 treatments promoted the SOC content by 4.82% and 13.60% compared with RM1 treatment at P1, respectively; RF15 and RF30 treatments increased the SOC content by 23.41% and 31.93% compared with RM2 treatment at P2, respectively. Additionally, RF5 treatment significantly increased the biomass of the soil microbial community in comparison with RM1 treatment, as did RF15 treatment and RF30 treatment compared with RM2 treatment, including the contents of total PLFA and the PLFA of gram-positive bacteria (G+), gram-negative bacteria (G−), actinomycetes, fungi, and bacteria. Activities of β-glucosidase, cellobiohydrolase, β-1,4-N-acetylglucosaminidase, and urease significantly increased in RF5 and RF30 treatments. The piecewise SEM results indicated that the changes of total PLFA content and the PLFA content ratio of fungi to bacteria were related to contents of dissolved organic C (DOC) and total N (TN) under different RF durations, which are key indicators affecting SOC content. Overall, SOC storage increases with the RF durations, and soil microbial community structure may drive soil C sequestration under long-term RF, which provides a scientific significance and practical value in promoting the sustainability of agricultural ecosystems, enhancing the potential of soil as a carbon sink, and addressing global climate change. Full article

Global climate change presents a significant challenge to aquatic ecosystems, with ectothermic fish being particularly sensitive to temperature fluctuations. The brain plays a crucial role in perceiving, regulating, and adapting to thermal changes, and its response to heat stress is crucial for survival. However, the molecular mechanisms underlying heat stress and acclimation in fish brains remain poorly understood. This study aimed to investigate the adaptive mechanisms of Hong Kong catfish (Clarias fuscus) brains under heat acclimation and acute heat stress using transcriptome analysis. Fish were divided into two groups: a normal temperature group (NT, 26 °C for 90 days) and a heat-acclimated group (HT, 34 °C for 90 days), followed by acute heat stress (34 °C for 72 h) and recovery (26 °C for 72 h). Heat acclimation improved C. fuscus tolerance to acute heat stress, with faster gene responses and stronger neuroprotection. Key pathways enriched included cell adhesion and ECM-receptor interactions during recovery. Apoptosis regulation was balanced, with the HT group upregulating anti-apoptotic genes to mitigate neuronal cell death. Additionally, the lysosome–phagosome pathway was activated during recovery, facilitating the transport of lysosomal enzymes and the clearance of damaged cellular components, aiding neuronal repair. Ribosome biogenesis was suppressed under heat stress to conserve energy, but this suppression was less pronounced in the HT group. In summary, heat acclimation enhances neural protection in C. fuscus brains by promoting neuronal repair, suppressing apoptosis, and activating lysosomal pathways, thereby improving tolerance to acute heat stress. These findings offer a molecular basis for breeding heat-tolerant fish species in aquaculture, and deepen our understanding of thermal adaptation in aquatic animals amid global climate change. Full article

Plastic pollution in aquatic ecosystems has become a global concern, and nanoplastics, due to their small size and high penetration potential, pose significant risks to aquatic organisms. This study aimed to evaluate the effects of polystyrene nanoplastics (PS-NPs) on oxidative stress biomarkers, blood biochemical parameters, and digestive enzyme activities in Goldfish (Carassius auratus). The experiment was conducted over 21 days, exposing fish to four different dietary concentrations of PS-NPs (0, 1, 10, and 100 mg/Kg). The results showed that chronic exposure to 50 nm PS-NPs significantly increased the activity of antioxidant enzymes (CAT, SOD, and GPx) and MDA activity in the gill, kidney, and liver tissues, indicating the induction of oxidative stress. Furthermore, notable alterations were observed in blood biochemical enzymes (alkaline phosphatase [ALP], alanine aminotransferase [ALT], aspartate aminotransferase [AST], and lactate dehydrogenase [LDH]), suggesting cellular damage and physiological disturbances. Additionally, PS-NP exposure affected the activity of digestive enzymes (amylase, lipase, and protease), which may impact nutrient digestion and absorption. These findings highlight that PS-NPs can adversely affect aquatic animal health and may influence the nutritional quality of fish. Therefore, further research is necessary to assess the long-term ecological and toxicological impacts of nanoplastics in freshwater ecosystems. Full article

Background/Objectives: Burns are a prevalent health concern that manifest on the skin’s surface or within organs due to various traumas and necessitate prompt intervention. The healing process of the skin involves a sequence of time-dependent events, commencing with the activation of growth factors and culminating in the expression of various genes. To expedite the healing process of burn wounds, there is a need to develop biodegradable materials and new technologies that are compatible with the skin. Methods: In this study, the roles of tilapia (TL, Oreochromis niloticus) fish skin in burn wound treatment processes were investigated. TL or TL-alginate hydrogels (AGTL) were applied to a burn wound created in Sprague Dawley rats for 7 and 14 days. Following the administration of treatment, the levels of hydroxyproline, a critical element in tissue reorganization, along with the gene expression levels of COL1A1, COL3A1, MMP-2, and MMP-9, and the protein expression levels of MMP-2 and MMP-9 were evaluated. Results: Wound closure processes were faster in AGTL-groups compared to TL-groups, and hydroxyproline levels were found to be higher. While the increase in MMP-2 levels was less, the increase in MMP-9 gene and protein levels was greater in the AGTL-group. Concurrently, COL1A1 levels decreased over 14 days, while COL3A1 levels increased in the AGTL-group. Conclusions: Consequently, it was determined that the biological substances in the TL structure, in conjunction with alginate, were effective in the healing and reorganization of the wound tissue. This finding suggests that tilapia may provide a valuable source of insights for future studies aimed at developing effective wound dressings for wound tissues. Full article

This study is to explore the alleviating effects of glutamate on intestinal damage in cultured little yellow croaker. A total of 900 juvenile fish at a weight of 30.68 ± 0.12 g were randomly separated into six groups with three replicates each, and were fed a basic diet (protein at 44.42% and lipid at 12.48%) with additional glutamate at 0.00%, 0.40%, 0.80%, 1.2%, 1.60%, and 2.00%. Each replica group consisted of 50 fish in a breeding barrel (radius 1.0 m, height 1.5 m), and the experiment lasted for 54 days. The results showed that supplementation with 0.4–1.2% glutamate significantly improved the survival rate, which increased from 75.56% to 91.11%, reduced the feed conversion rate from 1.75 to 1.57, and increased the protein efficiency ratio from 1.55 to 1.85 (p < 0.05). In the intestines, the addition of 0.40–1.2% glutamate increased muscle thickness and villus height (p < 0.05), as well as the activities of pepsin, trypsin, α-amylase, and lipase (p < 0.05). Enzyme activity analysis indicated that the addition of 0.4–1.2% glutamate in the feed significantly enhanced the activities of serum Total Superoxide Dismutase (T-SOD), catalase (CAT), and glutathione peroxidase (GPx) antioxidant enzymes (p < 0.05). Transcriptome analysis of the 1.2% and 0% groups revealed that differentially expressed genes were enriched in glutathione synthesis, nutrient absorption and metabolism, and viral protein interaction with cytokine and cytokine receptor pathways. qPCR experiments verified that the addition of 1.2% glutamate significantly up-regulated the expression of antioxidant-related genes, including glutathione synthetase and Nrf2. In conclusion, the addition of glutamate can enhance growth performance, increase intestinal digestive capacity, activate intestinal glutathione synthesis to alleviate intestinal damage, and maintain intestinal health. Full article

Vitamin K₃ (VK₃) is an essential micronutrient for fish growth and metabolism. To determine the optimal required dietary concentration of VK, a 12-week-long trial was planned to investigate the impact of VK₃ on growth performance, muscle composition, liver menaquinone-4 (MK-4), whole-body MK-4 concentration, and antioxidant capacity (T-AOC) in coho salmon alevins. A total of 2100 coho salmon alevins were divided into twenty-one tanks, with 100 alevins in each tank, and three tanks represented one group. Each of the seven groups were randomly assigned to one of the experimental diets formulated with varying levels of menadione nicotinamide bisulphite (VK₃), i.e., 0.16 (control), 5.25, 10.22, 14.93, 20.51, 40.09, and 59.87 mg/kg, respectively. The results revealed that the inclusion of VK₃ from 5.25 to 40.09 mg/kg improved (p < 0.05) the survival rate (SR), weight gain (WG), specific growth rate (SGR), and feed conversion ratio (FCR), while no effect (p > 0.05) was observed on the hepatosomatic index (HSI), viscerosomatic index (VSI), Fulton’s condition factor (K), and muscle composition. The whole-body MK-4, liver MK-4, liver T-AOC, total superoxide dismutase (T-SOD), and catalase (CAT) enzymes were also increased (p < 0.05). Malondialdehyde (MDA) contents were reduced (p < 0.05) in all supplemented groups with a decreasing trend. The predicted optimal required dietary concentrations of VK₃ were found to be 34.0, 43.5, 38.54, and 31.97 mg/kg based on WG, SGR, liver MK-4 concentration, and T-AOC, respectively, by quadratic regression analysis. It is concluded that the dietary VK₃ has improved the growth performance and antioxidant status in alevins during early development in the range of 31.97 to 43.5 mg/kg diet. Full article

Temperature is a critical environmental factor that influences the growth, development, metabolism, and overall physiological performance of fish. Eleutheronema tetradactylum is an economically significant fish species; however, its molecular mechanism’s response to long-term cold stress is still unclear. In this study, we investigated the physiological responses of the liver in E. tetradactylum exposed to a constant temperature of 18 °C for durations of both 7 and 14 days, utilizing liquid chromatography–mass spectrometry (LC-MS), metabolomics, and conventional biochemical assays. The antioxidant status, liver histology, and metabolite profiles were examined at different time points. Our results revealed that, following sustained cold exposure, the activities of key antioxidant enzymes—superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx)—initially increased and then decreased. Additionally, levels of malondialdehyde (MDA), a marker of oxidative damage, significantly elevated after 7 and 14 days of cold stress. Histopathological examination of liver tissues showed varying degrees of vacuolation and nuclear atrophy in hepatocytes, indicating oxidative damage. Metabolomic profiling identified 87 and 116 differentially expressed metabolites in the liver on days 7 and 14, respectively. Pathway enrichment analysis revealed significant alterations in pathways related to carbohydrate digestion and absorption, glutathione metabolism, and glycerolipid metabolism. These findings suggest that mechanisms regulating cell membrane fluidity, energy metabolism, autophagy, and antioxidant defense are crucial for the adaptation of E. tetradactylum to cold stress. Overall, this study provides valuable insights into the molecular and physiological adaptations of E. tetradactylum to low temperature, highlighting the activation of protective antioxidant responses and modifications of metabolic pathways in the liver. Full article

The distribution of saline-alkali water is extensive and is increasing globally each year. Fully utilizing saline-alkali water for aquaculture can help alleviate the scarcity of freshwater resources in global fisheries. As a major economic fish species, the largemouth bass (Micropterus salmoides) holds significant potential for aquaculture in saline-alkali water. In the present study, we evaluated its tolerance to different salinities (0 ppt, 6 ppt, 9 ppt, 12 ppt, 15 ppt, and 18 ppt) and investigated tissue pathology, serum biochemical indicators, enzyme activities of osmolality and antioxidant, and the relative expression of Na-K-2Cl 1a cotransporter (NKCC1a) under different saline stress (0 ppt, 6 ppt, 9 ppt, and 12 ppt). The largemouth bass 96 h mortality rate increased with increasing salinity, and the LC₅₀ for 96 h was 14.28 ppt based on the mortality results. High salinity group (12 ppt) caused gill and intestinal damage, including necrosis and cell shedding, while 6 ppt had no adverse effects, and the 9 ppt between the two salinities showed an adaptive change histologically. Serum osmolality, Na⁺, Cl⁻, and cortisol levels of the high salinity group were significantly higher than of the low salinities (p < 0.05). Similarly, Na⁺/K⁺-ATPase (NKA), Ca²⁺-Mg²⁺-ATPase (CMA), and superoxide dismutase (SOD) activities of 12 ppt peaked at 24 h (15.7 U/mgprot, 11.5 U/mgprot, and 243 U/mgprot), which is significantly different compared to the other three groups (p < 0.05). The expression of NKCC1a was significantly upregulated at 9 ppt and 12 ppt, suggesting its role in osmoregulation. Furthermore, the expression of NKCC1a in the gill is 2–4 times higher than that in the intestine. These results suggested that largemouth bass can be cultured at 6 ppt and selectively bred for tolerance at 9 ppt. NKA activity, cortisol levels, and NKCC1a expression can be used as a marker of salinity suitability. These findings provide insight into the adaptive mechanisms underlying the physiological responses to acute salinity stress and will contribute to improving aquaculture in saline waters. Full article

This study investigated the effects of dietary supplementation with Mentha piperita (MP) on growth, immune enhancement, and disease resistance in Nile tilapia (Oreochromis niloticus) over a 90-day period, particularly against Aeromonas hydrophila. MP was incorporated into the diets at concentrations of 0.0%, 0.2%, 0.4%, and 0.6%. Analysis of the essential oil composition of MP identified menthol derivatives as the primary components, along with other bioactive compounds. The results revealed that MP supplementation significantly enhanced growth performance, with fish receiving the 0.6% MP diet achieving the highest weight gain, growth rate, and feed efficiency. Additionally, MP significantly enhanced the fish’s resistance to A. hydrophila infection, with the highest survival rate observed in the 0.6% MP group. Further analyses revealed that MP positively influenced blood parameters, improving RBC and WBC counts, hemoglobin levels, as well as serum immunoglobulin M and phagocytic activity. MP also mitigated oxidative stress by increasing antioxidant enzyme activity and reducing malondialdehyde levels. Moreover, MP supplementation at the concentration of 0.6% maintained intestinal integrity against bacterial damage. Gene expression analysis showed that MP upregulated insulin-like growth factor 1, suggesting a potential mechanism for improved growth. Interestingly, MP downregulated the expression of the inflammatory gene nuclear factor kappa B before the bacterial challenge, while its expression remained more downregulated post-challenge compared to control. These findings highlight the potential of MP as an effective feed additive that enhances growth rates in Nile tilapia, boosts immunity against diseases, and improves their overall health. Full article

Proteins for elongation of very long-chain fatty acids (ELOVLs) are critical for the synthesis of long-chain polyunsaturated fatty acids (LC-PUFAs), and they are one group of the rate-limiting enzymes responsible for the initial condensation reaction within the fatty acid elongation. Elovl8 is a newly identified member of the ELOVL protein family, and its evolutionary and functional characterizations are still rarely reported. Here, we identified two elovl8 paralogues (named Scelovl8 and Scelovl8b) from Chinese perch (Siniperca chuatsi), and then their molecular and evolutionary characteristics, as well as potential roles involved in LC-PUFA biosynthesis, were examined. The ORFs of both Scelovl8a and Scelovl8b genes were 810 bp and 789 bp in length, encoding proteins of 270 and 263 amino acids, respectively. Multiple protein sequence comparisons indicated that elovl8 genes were highly conserved in teleosts, showing similar structural function domains. Meanwhile, phylogenetic analysis showed that the elovl8 gene family was clustered into two subclades of elovl8a and elovl8b, and Scelovl8a and Scelovl8b shared close relationships with banded archerfish elovl8a and striped bass elovl8b, respectively. Genetic synteny and gene structure analyses further confirmed that elovl8b is more conserved in comparison to elovl8a in teleosts. In addition, Scelovl8a was found to be highly expressed in the liver, while Scelovl8b was most abundant in the gills. Long-term food deprivation and refeeding are verified to regulate the transcription of Scelovl8a and Scelovl8b, and intraperitoneal injection of fish oil (FO) and vegetable oil (VO) significantly modified their gene expression as well. In summary, our results in this study indicate that elovl8 genes were conservatively unique to teleosts, and both elovl8 genes might be involved in the endogenous biosynthesis of LC-PUFAs in Chinese perch. These findings not only expand our knowledge on the evolutionary and functional characteristics of both elovl8 genes but also lay a solid basis for investigating regulatory mechanisms of LC-PUFA biosynthesis in various teleosts. Full article

The expansion of fisheries and aquaculture in recent decades has led to a substantial increase in fish by-products. This study investigates the extraction and characterization of calcium phosphates from the by-products of representative species in these industries, aiming to identify potential sources for biotechnological and pharmaceutical applications. Clean bones obtained by enzyme hydrolysis from the heads, central skeletons, and/or tails of Atlantic horse mackerel, blue whiting, hake, mackerel, and farmed turbot were subjected to calcination to obtain calcium phosphates. The clean bone content in terms of nitrogen, lipids, organic matter, total protein, and amino acids was evaluated together with the chemical bonds, structures, and elemental composition of calcium phosphates. Results indicated a significantly higher yield of wet bone recovery (23%, p < 0.05) for the central skeleton of Atlantic horse mackerel and the highest mineral fraction for the heads of Atlantic horse mackerel (73.2%), followed by that of blue whiting (72.6%). Hake and turbot presented the lowest mineral fractions and, therefore, the highest protein content (27–31%, p < 0.05), with significant levels of collagen-related amino acids (p < 0.05). X-ray diffraction (XRD) and Fourier-transform Raman spectroscopy (FT-Raman) confirmed the biphasic calcium phosphate composition for most samples based on hydroxyapatite with contributions of whitlockite/β-tricalcium phosphate. The highest contribution to the non-apatite phase was made by the central skeletons of both mackerel and Atlantic horse mackerel. Full article

The marine environment, covering over 70% of the Earth’s surface, serves as a reservoir of bioactive molecules, including peptides and proteins. Due to the unique and often extreme marine conditions, these molecules exhibit distinctive structural features and diverse functional properties, making them promising candidates for therapeutic applications. Marine-derived bioactive peptides, typically consisting of 3 to 40 amino acid residues—though most commonly, 2 to 20—are obtained from parent proteins through chemical or enzymatic hydrolysis, microbial fermentation, or gastrointestinal digestion. Like peptides, protein hydrolysates from collagen, a dominant protein of such materials, play an important role. Peptide bioactivities include antioxidant, antihypertensive, antidiabetic, antimicrobial, anti-inflammatory, anticoagulant, and anti-cancer effects as well as immunoregulatory and wound-healing activities. These peptides exert their effects through mechanisms such as enzyme inhibition, receptor modulation, and free radical scavenging, among others. Fish, algae, mollusks, crustaceans, microbes, invertebrates, and marine by-products such as skin, bones, and viscera are some of the key marine sources of bioactive proteins and peptides. The advancements in the extraction and purification processes, e.g., enzymatic hydrolysis, ultrafiltration, ion-exchange chromatography, high-performance liquid chromatography (HPLC), and molecular docking, facilitate easy identification and purification of such bioactive peptides in greater purity and activity. Despite their colossal potential, their production, scale-up, stability, and bioavailability are yet to be enhanced for industrial applications. Additional work needs to be carried out for optimal extraction processes, to unravel the mechanisms of action, and to discover novel marine sources. This review emphasizes the enormous scope of marine-derived peptides and proteins in the pharmaceutical, nutraceutical, cosmeceutical, and functional food industries, emphasizing their role in health promotion and risk reduction of chronic diseases. Full article

The mercury (Hg) present in ocean fish has caused concern regarding the effects of maternal consumption on child outcomes but it is now recognized that mothers that eat more ocean fish during pregnancy have children with higher social, scholastic, and IQ scores. These findings coincide with the current understanding of the mechanism of Hg toxicity which indicates ocean fish consumption will prevent rather than cause harm. High-Hg exposures sequester selenium (Se) and inhibit Se-dependent enzymes that prevent and reverse oxidative damage in the brain and support fetal brain development. However, aside from certain types of shark and other apex marine predators, seafood contains more Se than Hg and thus counteracts instead of contributing to Hg toxicity. This study evaluates the Hg and Se present in bigeye tuna, yellowfin tuna, albacore tuna, skipjack, swordfish, striped marlin, blue marlin, spearfish, mahimahi, wahoo, monchong, escolar, mako shark, and thresher shark to establish their health benefit values (HBVs). Positive HBVs (0.3–19.6), indicating a molar excess of Se over Hg, were found in 14 of the 15 species studied. Only mako shark uniformly contained Hg in excess of Se to produce a negative HBV (−16.4), indicating its consumption should be minimized during pregnancy. Full article

Variations in salinity levels in aquaculture significantly influence fish physiology, impacting population dynamics and industry viability. This study aimed to examine the physiological response of the freshwater drum (Aplodinotus grunniens) to differing salinity conditions, assessing its potential for cultivation in brackish water environments. Fish averaging 45 ± 0.1 g were subjected to acute salinity tests across three groups: a control group at 0‰ and experimental groups at 7.5‰ and 15‰ over four days. The initial findings indicated that A. grunniens could tolerate salinity levels up to 15‰ without adverse effects. Key biochemical markers, such as aspartate aminotransferase and alanine aminotransferase, exhibited significant fluctuations but decreased over time. Antioxidant enzyme activity increased relative to the control, while malondialdehyde levels declined, indicating effective oxidative stress management. Additionally, digestive enzymes like amylase and lipase demonstrated adaptability to changing salinity. The expression of heat shock proteins 70 and 90 in the gills and livers varied initially but showed no sustained changes. Overall, the results suggest that A. grunniens possesses notable resilience to salinity variations, indicating its suitability for brackish water aquaculture and highlighting the optimal salinity ranges for promoting growth. Full article