Search Results (165)

Fish are widely recognized as effective bioindicators in ecotoxicological studies due to their repeated exposure to aquatic pollutants that accumulate in metabolically active organs, often leading to histopathological changes. In aquaculture, cage-farmed fish experience continuous environmental and culture-related stress, which can affect renal integrity. The kidney, a central osmoregulatory organ, is particularly sensitive to such conditions. Renal tissues were collected from different growth stages of cage-farmed rainbow trout. Hematoxylin and eosin staining was performed to detect morphological alterations, while transmission electron microscopy was used to assess cellular damage at the ultrastructural level. The expression of fibronectin and caspase-3, markers of extracellular matrix remodeling and apoptosis, respectively, was also evaluated. TEM examination showed pronounced alterations in both the glomeruli and renal tubules, accompanied by increased expression of fibronectin and caspase-3, indicating ongoing tissue remodeling and cellular stress. This study demonstrates that cage-farmed rainbow trout exhibit progressive ultrastructural kidney alterations that appear to be associated with environmental confinement, nutritional practices, and prophylactic treatments. These conditions collectively contribute to renal stress and the onset of nephropathic changes in aquaculture settings. Further research should focus on molecular marker expression to better understand renal adaptation and injury progression under intensive farming conditions. Full article

Changes in food consumption are closely related to food production, loss, and waste. Few studies focused on people’s adaptation to climate warming through changes in food consumption quantity. This study examined how climate warming in the current year and the preceding year affects the per capita consumption quantity of 14 food items, identifying both passive and active adaptations. The study employed a dynamic panel data regression model based on annual average daily temperatures from 1985 to 2022 in 30 provinces of China. We found that Chinese residents actively adapted to climate warming by increasing their consumption of pork, mutton, eggs, and beef while decreasing their intake of dairy products, aquatic products, vegetable oil, beans and tubers, and animal fats. They passively adapted to climate warming by increasing their consumption of dried and fresh fruits, aquatic products, vegetable oil, animal fats, poultry, and beans and tubers while decreasing their consumption of grains, pork, dairy products, and beef. Moreover, climate warming drove region and income specific dietary shifts through active and passive adaptations that raise pork eggs grains and oils while cutting beef poultry beans and tubers across South/North and rich/poor areas. These findings will help policymakers achieve the goal of sustainable food consumption by aligning climate, nutrition, and equity targets for resilient food-system transitions. Full article

Salinity is a pivotal environmental factor that significantly influences the survival, growth, development, and reproduction of aquatic organisms. However, the characteristics of serum metabolites and their mechanistic roles in mediating the response of grass carp (Ctenopharyngodon idellus) to long-term salinity stress remain incompletely understood. Therefore, the present study exposed grass carp to different salinity levels (0, 4, and 8 g/L) for 60 days to evaluate the associated physiological alterations and metabolic responses. The results revealed that high salinity (8 g/L) significantly suppressed growth performance (p < 0.05), whereas low salinity (4 g/L) caused no significant reduction in growth or survival. Physiological analyses indicated that fish in the 8 g/L group exhibited markedly reduced levels of lactic acid and total protein, along with elevated concentrations of total cholesterol, triglycerides, glucose, and glutamic-oxaloacetic transaminase (p < 0.05). Serum ion homeostasis was also disrupted under high salinity, characterized by increased Ca²⁺, Na⁺, and Cl⁻ levels and decreased Mg²⁺ (p < 0.05). Furthermore, oxidative stress was evident in the high-salinity group through heightened activities of antioxidant enzymes (SOD, CAT, GPx), accumulation of oxidative damage markers (protein carbonyl, 8-OHdG) (p < 0.05). Metabolomic profiling identified 367 and 403 significantly altered metabolites in the 4 g/L and 8 g/L groups, respectively, primarily belonging to lipids and lipid-like molecules along with organic acids and derivatives. KEGG enrichment analysis revealed that these differential metabolites were chiefly involved in amino acid biosynthesis, glycerophospholipid metabolism, biosynthesis of unsaturated fatty acids, and glycine, serine, and threonine metabolism. Trend analysis further uncovered eight distinct expression patterns of metabolites across salinity gradients. These results provide novel insights into the metabolic adaptations of grass carp to salinity stress, demonstrating that high salinity induces oxidative stress, disrupts ion regulation, and drives extensive metabolic reprogramming. The study offers valuable theoretical support for improving salinity tolerance management in aquaculture and informs the selective breeding of salt-tolerant fish strains. Full article

Hypoxic stress is an important environmental challenge for aquatic organisms, which is detrimental to fish survival and growth. Specifically, the NOD-like receptor thermal protein domain associated protein 3 (NLRP3) has emerged as a pivotal regulator, with accumulating evidence underscoring its central role in inflammatory processes. However, the regulatory functions of NLRP3 during hypoxic stress in fat greenling (Hexagrammos otakii) remain elusive. In this study, we systematically analyzed the molecular features of HoNLRP3 and elucidated its biphasic regulatory mechanism under hypoxic stress in H. otakii using phylogenetic analysis, qRT-PCR, Western blot, and immunofluorescence. Its phylogeny is significantly different from that of mammals and carries FISNA and related motifs specific to bony fishes. Hypoxia induced predominant nlrp3 expression in the brain, peaking at 12–24 h, with strong positive correlation to hif-1α activation. NLRP3-ASC-Caspase1 inflammasomes assembly drove IL-1β maturation, while prolonged hypoxia (48 h) activated Caspase3/GSDME-mediated pyroptosis, accompanied by elevated LDH activity. Reoxygenation partially reversed inflammatory and pyroptosis markers, indicating that NLRP3 balances defense and injury through a biphasic regulatory mechanism. This study provides new insights into the hypoxic adaptation mechanisms in bony fish. Full article

Rapid urbanization and increased anthropogenic activities have led to the release of an increasing number of pollutants, including metals, into freshwater ecosystems, posing a significant threat to aquatic life. In this study, the bioaccumulation of metals and hepatic enzyme activities in northern pike (Esox lucius) from two contrasting freshwater ecosystems in Serbia, the lotic Tisza River and the lentic Bela Crkva Reservoirs, were investigated. A total of 22 specimens (11 per site) were sampled in autumn 2024. The liver tissue was analyzed for the concentrations of 11 metals (As, Cd, Cr, Co, Cu, Pb, Li, Fe, Zn, Mn, Ni) and the activities of the liver enzymes (ALT, AST, AP, GGT). The results showed ecosystem-specific patterns of metal accumulation, with the northern pike in the rivers showing significantly higher Cu and Fe levels, while the fish in the reservoirs showed increased Zn concentrations. Enzymatic biomarkers showed different responses between ecosystems, with river fish showing increased ALT and AST activities, indicating hepatocellular stress, while reservoir fish showed increased GGT, indicating enhanced detoxification processes. The body condition factor was negatively correlated with liver Mn and Zn concentrations, emphasizing its utility as an integrative bioindicator of metal-induced stress. No significant sex-specific differences in metal or enzyme levels were found. These results suggest the suitability of northern pike as a sentinel species for environmental monitoring in freshwaters and highlight the different physiological adaptations to local metal stress in lentic and lotic habitats. Full article

The widespread presence of bisphenol A (BPA), a persistent endocrine-disrupting pollutant, in aquatic environments poses significant ecological and health risks, necessitating its effective removal. However, conventional remediation technologies are often hampered by catalysts with narrow pH adaptability and poor stability. In this study, a novel catalyst, Zeolite-supported Cu₃Mn-layered double hydroxide (LDH), was fabricated using the co-precipitation method. The synthesized catalyst was applied to activate peroxymonosulfate (PMS), effectively enabling decomposition of BPA by advanced oxidation processes. The composite material was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM), which confirmed the successful synthesis of the zeolite-supported Cu₃Mn-LDH. The catalyst exhibited high activity in both neutral and strongly alkaline environments, achieving complete degradation of 10 mg⋅L⁻¹ bisphenol A (BPA) within 40 min and a 98% total organic carbon (TOC) removal rate when both the PMS and catalyst were dosed at 0.15 g⋅L⁻¹. Singlet oxygen was detected as the primary reactive species responsible for BPA degradation, as verified by quenching experiments and EPR analysis, which also identified the presence of sulfate (SO₄^•−), hydroxyl (•OH), and superoxide (•O₂⁻) radicals. The catalyst exhibited excellent reusability, maintaining high catalytic efficiency over two consecutive cycles with minimal performance loss. Gas chromatography-mass spectrometry (GC-MS) analysis revealed five intermediate products, enabling the proposal of potential BPA degradation pathways. This work not only presents a novel synthetic approach for zeolite-supported LDH composites, but also offers a promising strategy for the efficient removal of BPA from aqueous systems through AOPs. Full article

The domestication of common carp in rice paddies (5–20 cm depth) is challenging, as the fish must withstand drastic fluctuations in temperature and dissolved oxygen, restricted movement, and bird predation without the option of diving. The effects of stress responses in different species of carp in shallow-water environments remain poorly understood, particularly with fluctuating water levels where real-time monitoring is challenging. This study employed a glucose biosensor system enabling real-time monitoring, together with biochemical analysis techniques capable of evaluating multiple physiological indicators, to investigate shallow-water adaptation in Qingtian paddy field carp and Xingguo red carp. Our results quantitatively reveal, for the first time, the differing physiological stress thresholds of the two carp strains under shallow water. The Qingtian paddy field carp exhibited a higher tolerance to shallow water and showed faster recovery from prolonged stress. Furthermore, the total cholesterol and triglyceride contents of Qingtian paddy field carp gradually increased with prolonged shallow-water stress, reflecting the activation of lipid metabolic pathways. These findings highlight the advantages of biosensor technology in aquatic stress research and a strong support of the core element of paddy domesticated carp in the Globally Important Agricultural Heritage Systems. Full article

Hydrogen peroxide (H₂O₂), a ubiquitous reactive oxygen species in aquatic ecosystems, has been shown to induce toxicological effects in aquatic animals. However, the molecular mechanisms underlying H₂O₂-mediated alterations in muscle quality and metabolic homeostasis remain largely unexplored. In this study, we performed integrated metabolomic and transcriptomic analyses to characterize the molecular mechanisms underlying H₂O₂-induced oxidative stress in fish muscle tissue. Common carp (Cyprinus carpio) were randomized into two groups: a control group (0.0 mM H₂O₂) and an H₂O₂-treated group (1.0 mM H₂O₂) for a 14-day exposure. Following the exposure, comprehensive analyses, including fatty acid composition, amino acid profiles, and multi-omics sequencing, were conducted to elucidate the metabolic responses to oxidative stress. The results showed neither the amino acid nor the fatty acid composition exhibited significant modifications following H₂O₂ exposure. Metabolomic profiling identified 83 upregulated and 89 downregulated metabolites, predominantly comprising organic acids and derivatives, lipids and lipid-like molecules. These differential metabolites were associated with histidine and purine-derived alkaloid biosynthesis, glyoxylate and dicarboxylate metabolism pathways. Transcriptomic analysis identified 470 upregulated and 451 downregulated differentially expressed genes (DEGs). GO enrichment analysis revealed that these DEGs were significantly enriched in muscle tissue development and transcriptional regulatory activity. KEGG analysis revealed significant enrichment in oxidative phosphorylation, adipocytokine signaling, and PPAR signaling pathways. The elevated oxidative phosphorylation activity and upregulated adipocytokine/PPAR signaling pathways collectively indicate H₂O₂-induced metabolic dysregulation in carp muscle. Through the integration of metabolomics and transcriptomics, this study offers novel insights into the toxicity of H₂O₂ in aquatic environments, elucidates adaptive mechanisms of farmed fish to oxidative stress, and provides a theoretical basis for developing antioxidant strategies. Full article

Thermal algae are extremophilic organisms that live in one of the harshest environments in the world and thrive in waters with temperatures of up to 90 °C. They have gained attention due to their special ecological adaptations, their great biotechnological potential and their recently recognised role in combating global climate change and achieving sustainable development. However, the biodiversity of these algae is far from being fully explored. The article presents the first finding of the prokaryotic genus Asterocapsa (Chroococcales, Cyanophyceae, Cyanoprokaryota/Cyanobacteria) in thermal waters and describes a new species from the fountain basins in the thermal system of the only continental European geyser (101 °C) in the town of Sapareva Banya (south-west Bulgaria). This species is not only one of the few aquatic representatives of this generally aeroterrestrial genus, but is also characterised by its extremophilic lifestyle and differs clearly from the type species and other aquatic species of the genus due to its morphological characteristics. These include the smaller dimensions of the cells and colonies, as well as the colourless, transparent, but always lamellar and regularly verrucous mucilage envelopes. The unique locality of this alga is highly endangered and was included in the first Red List of Bulgarian wetlands. Due to human activities and changes in the geyser system, we have detected some unfavourable changes in the algal habitat and therefore propose to add the newly described species to the Red List of Bulgarian Microalgae with the status Critically Endangered. Full article

The global gold extraction industry has been reported to use cyanide-based recovery processes, which pose environmental effects on water resources. The study examined Coptodon zillii liver rhodanese from a gold mining-impacted reservoir with a specific focus on the enzyme’s critical function in cyanide detoxification. Rhodanese was purified using successive chromatographic techniques with 5.4 U/mg specific activity and 3.1-fold purification. The molecular weight of the native enzyme was 36 kDa, and the subunits were 17 kDa, indicative of a dimeric structure. Optimal enzymatic activity was recorded at pH 8.0 and 50 °C. The effect of metal ions was significantly varied: the activity was inhibited by BaCl₂, CaCl₂, NaCl, and MgCl₂, and KCl enhanced performance. The kinetic determinations showed Michaelis-Menten kinetics with a Km of 20.0 mM for sodium thiosulfate and 25.0 mM for potassium cyanide. The enzyme’s minimal activity was identified toward 2-mercaptoethanol, ammonium persulfate, and ammonium sulfate, but with evidence of preference for thiosulfate utilization under the substrate specificity tests. The major interactions between the enzyme and the substrate were revealed by the molecular docking experiments. These showed Glu159, Gln161, and Arg173 formed important hydrogen bonds with thiosulfate, while Arg156 and Val172 were also involved. Other substrates are bound to Gln121 and Trp139 residues with much lower binding energy than thiosulfate. The findings increase our understanding of biochemical adaptation process knowledge in anthropogenically stressed environments, showing strategies of ecological resilience. The characterized enzymatic features showed potent cyanide detoxification potential, and the possible applications are in bioremediation strategies for mining-impacted aquatic ecosystems. Full article

Surface subsidence caused by coal mining activities generates diverse wetland ecosystems. These newly formed wetlands exhibit distinct environmental characteristics due to variations in subsidence age, resulting in divergent biological communities. While species adapt to environmental changes through specific functional trait combinations, the response of aquatic community functional diversity to environmental gradients across chronosequences of mining subsidence wetlands remains unclear. This study investigated 13 coal mining subsidence wetlands (1–18 years) of macrozoobenthos in Jining, China. Through seasonal monitoring, we analyzed functional traits along with taxonomic and functional diversity patterns. Initial-stage wetlands were dominated by medium-sized (63.9%) and tegument-respiring taxa, whereas late-stage wetlands exhibited a shift toward large-sized (43.9%) and gill-respiring groups. Both species richness and functional richness declined over time, with taxonomic diversity demonstrating greater sensitivity to subsidence age. Seasonal community variability was more pronounced in initial-stage wetlands (1–4 years post-subsidence). Despite increasing habitat heterogeneity with subsidence age, functional redundancy maintains ecosystem stability. The shared origin and developmental trajectory of these wetlands may constrain functional divergence. Current research predominantly relies on traditional taxonomic metrics, whereas our findings emphasize functional trait analysis’s importance for ecosystem assessment, which provides a theoretical framework for ecological restoration and biodiversity conservation in post-subsidence wetlands. Full article

Ammonia is a common toxic pollutant in aquaculture environments that poses significant threats to the health, growth, and survival of aquatic organisms. This study investigates the physiological and molecular responses of triploid Crassostrea gigas to ammonia exposure, focusing on the activation and regulation of oxidative stress and immune-related pathways. By integrating histological observations, biochemical assays, and transcriptomic analysis, we systematically revealed the oxidative stress and immune regulatory mechanisms in the hepatopancreas of triploid C. gigas under ammonia exposure. Results showed significant tissue damage in the hepatopancreas, disrupted activities of key antioxidant enzymes including SOD, CAT, and GSH-Px, along with elevated MDA levels, indicating oxidative damage to cellular membrane lipids. Transcriptomic data further indicated significant activation of the glutathione metabolism pathway, with antioxidant genes such as GPX5 and GPX7 displaying a dynamic pattern of initial upregulation followed by downregulation, suggesting their critical roles in modulating oxidative stress responses and maintaining cellular homeostasis. Immunologically, ammonia exposure significantly activated lysosomal and phagosomal pathways, as well as multiple signaling cascades including FOXO, mTOR, and PI3K-Akt. Several key immune regulatory genes exhibited dynamic expression changes, reflecting coordinated regulation of apoptosis, autophagy, and energy metabolism to maintain immune defense and cellular homeostasis. Notably, dynamic expression of the GADD45 gene family in the FOXO signaling pathway underscores the important role of triploid C. gigas in mounting stress responses and adaptive immune regulation under ammonia toxicity. This study provides in-depth molecular insights into the integrated response mechanisms of triploid oysters to ammonia exposure, offering a molecular foundation for understanding bivalve adaptation to ammonia and revealing novel perspectives on molluscan ammonia tolerance. Full article

Aluminium (Al) is a widespread environmental contaminant known to induce oxidative stress and genotoxic effects in aquatic organisms. While its neurotoxic properties are well documented, the molecular impact of Al on the visual system remains poorly understood. In this study, adult zebrafish (Danio rerio) were exposed to 11 mg/L Al for 10, 15, and 20 days to investigate the oxidative and genotoxic responses in ocular tissue. Activities of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) were measured in eye supernatants to detect oxidative stress. Additionally, the activities of poly (ADP-ribose) polymerase (PARP) and poly (ADP-ribose) glycohydrolase (PARG) were assessed in tissue homogenates to evaluate oxidative DNA damage and repair processes. The results indicate that these enzymes respond to counteract the increased reactive oxygen species (ROS) induced by aluminium exposure. However, their activity may not sufficiently reduce ROS levels to fully prevent oxidative DNA damage, as evidenced by a significant rise in PARP activity during short exposure times. Over longer exposures, PARP activity returned to baseline, suggesting ocular cells may adapt to aluminium toxicity. We propose that this reduction in PARP activity is a cellular survival mechanism, as sustained activation can deplete energy reserves and trigger cell death. Finally, thin-layer chromatography confirmed that PARG facilitates the breakdown of poly (ADP-ribose) (PAR) into ADP-ribose, demonstrating the dynamic regulation of the PAR cycle, which is crucial to preventing parthanatos. Full article

Macrobrachium nipponense represents a commercial decapod species that predominantly inhabits freshwater ecosystems or environments with low salinity. However, the species exhibits normal survival and reproductive capacity in natural aquatic habitats with salinity levels up to 10 parts per thousand (ppt). The present study aimed to elucidate the molecular mechanisms underlying salinity acclimation in M. nipponense by investigating alterations in oxidative stress, morphological adaptations, and hepatopancreatic gene expression profiles following exposure to a salinity level of 10 ppt. The present study demonstrates that glutathione peroxidase and Na⁺/K⁺-ATPase play critical roles in mitigating oxidative stress induced by elevated salinity in M. nipponense. Furthermore, histological analysis revealed distinct pathological alterations in the hepatopancreas of M. nipponense following 7-day salinity exposure, including basement-membrane disruption, luminal expansion, vacuolization, and a marked reduction in storage cells. Transcriptomic profiling of M. nipponense hepatopancreas suggested coordinated activation of both immune (lysosome and protein processing in endoplasmic reticulum pathways) and energy (pyruvate metabolism, glycolysis/gluconeogenesis, and citrate cycle) metabolic processes during salinity acclimation in M. nipponense. Quantitative real-time PCR validation confirmed the reliability of RNA-seq data. This study provides molecular insights into the salinity adaptation mechanisms in M. nipponense, offering potential applications for improving cultivation practices in brackish water environments. Full article

Elodea nuttallii is a significant submerged macrophyte utilized in shrimp and crab aquaculture, yet it exhibits low thermotolerance. This study investigated the physiological responses and transcriptomic characteristics of E. nuttallii under high-temperature stress (HTS). The results indicated that HTS significantly reduced the absolute growth rate (AGR) and photosynthetic efficiency of E. nuttallii while concurrently elevating antioxidant enzyme activities, malondialdehyde (MDA) content, and concentrations of osmotic adjustment compounds. Furthermore, the apical segments of E. nuttallii demonstrated greater sensitivity to HTS compared to the middle segments. Under exposure to 35 °C and 40 °C, antioxidant enzyme activities, MDA content, and osmotic adjustment compound levels were significantly higher in the apical segments than in the middle segments. Transcriptomic analysis revealed 7526 differentially expressed genes (DEGs) in the apical segments at 35 °C, a number substantially exceeding that observed in the middle segments. Enrichment analysis of DEGs revealed significant upregulation of key metabolic regulators under HTS, including carbohydrate metabolism genes (HXK, FRK) and phenylpropanoid biosynthesis enzymes (4CL, COMT). This transcriptional reprogramming demonstrates E. nuttallii’s adaptive strategy of modulating carbon allocation and phenolic compound synthesis to mitigate thermal damage. Our findings not only elucidate novel thermotolerance mechanisms in aquatic plants but also provide candidate genetic targets (HXK, 4CL) for molecular breeding of heat-resilient cultivars through transcriptomic screening. Full article