Silver nanoparticles (AgNPs) synthesized from Aspergillus niger IBCLP20 exhibit strong antimicrobial properties; however, strategies to mitigate their environmental risks remain insufficiently validated across contrasting aquatic systems. Here, we assessed calcium alginate encapsulation (AgNPsIBCLP20/CA) as a safe-by-design approach, integrating silver release dynamics with short-term ecotoxicity in freshwater and marine species. In this context, safe-by-design refers to the use of calcium alginate microcapsules to modulate the release of dissolved silver from mycogenic AgNPs intended for water disinfection, thereby reducing and delaying peak exposure without altering the intrinsic toxicity of silver. Silver concentrations were quantified using ICP-MS and energy-dispersive X-ray fluorescence spectroscopy. Leachate-based assays revealed higher sensitivity in marine taxa, with Paracentrotus lividus (LOEC = 1%) and Daphnia magna (LOEC = 0.781%) were the most responsive species, while freshwater Danio rerio embryos and Raphidocelis subcapitata were unaffected. Silver release strongly depended on medium ionic strength, decreasing from 19.3 μg⋅L−1 in ultrapure water to 0.83 μg⋅L−1 in hard water. Hazard assessment yielded lower predicted no-effect concentration (PNEC) values for AgNPsIBCLP20/CA in freshwater than in seawater, indicating ecosystem-specific mitigation performance. These findings demonstrate that the ionic composition governs nanoencapsulation efficiency and that risk reduction strategies for biogenic AgNPs cannot be generalized across aquatic environments. Our results provide quantitative support for integrating encapsulation performance into environmental risk assessment frameworks for antimicrobial nanomaterials. Because the degradation of the alginate matrix may remobilize additional silver over time, encapsulation should be viewed as a hazard mitigation and exposure modulation strategy rather than a permanent elimination of silver-related risks.
Grass carp reovirus (GCRV) is the primary etiological agent of viral hemorrhagic disease in grass carp (Ctenopharyngodon idella) and other cyprinids, causing devastating economic losses in freshwater aquaculture worldwide. The existence of multiple pathogenic genotypes (particularly GCRV-I and GCRV-II) and the lack of broadly effective, virus-specific therapeutics underscore an urgent need for host-directed antiviral strategies. However, whether targeting host chaperone systems can control aquatic viral diseases remains largely unknown. Herein, we evaluated the antiviral efficacy and mechanistic basis of AUY922, a specific inhibitor of heat shock protein 90 (HSP90), against GCRV infection using both in vitro (CIK cells) and in vivo (Gobiocypris rarus) models. AUY922 exhibited potent antiviral activity with low cytotoxicity, showing a half-maximal inhibitory concentration (IC50) of 5.96 nM. Prophylactic, therapeutic, and co-incubation treatments all significantly suppressed GCRV-I replication in vitro. In a highly susceptible GCRV-II challenge model, prophylactic administration of AUY922 (10 mg/kg) significantly increased survival rates from 18.18% to 59.09%, reduced tissue viral loads and markedly alleviated systemic hemorrhage as well as histopathological lesions in the gills, kidney, and brain. Mechanistically, AUY922 downregulated the transcription of putative host entry receptors and was accompanied by reduced inflammatory and apoptotic responses during GCRV infection. Collectively, these findings demonstrate that pharmacological inhibition of HSP90 effectively abrogates GCRV pathogenesis, accompanied by reduced expression of viral entry-associated factors, and weaker inflammatory and apoptotic responses. AUY922 therefore represents a promising host-directed antiviral candidate against GCRV and provides proof of concept that targeting host chaperone networks may be a broader strategy for controlling aquatic viral diseases.
The dmrt (doublesex and mab-3 related transcription factor) gene family is pivotal in sex determination, gonadal differentiation, and developmental patterning in vertebrates, including flatfish. To further understand the evolution and potential functions of dmrt in flatfish, we conducted a genome-wide characterization of dmrt genes in the Chinese tongue sole (Cynoglossus semilaevis). Six genes—dmrt1, dmrt2a, dmrt2b, dmrt3, dmrt4, and dmrt5—were identified in the species, all containing a conserved DM (doublesex and mab-3) DNA-binding domain. Phylogenetic and synteny analyses revealed a well-conserved dmrt1/2/3 genomic cluster, suggesting strong evolutionary constraints and functional interdependence within teleosts. Tissue-specific transcriptome profiling demonstrated distinct sex-biased expression patterns among dmrt genes. Strikingly, dmrt2a exhibited significant upregulation in pseudo-males compared to females, providing evidence of its potential involvement in pseudo-male testis formation. Proteomic and transcriptomic analyses further indicated that dmrt2a may act upstream of key signaling cascades, including transforming growth factor-beta (TGF-β), mitogen-activated protein kinase (MAPK), and Wnt pathways, while repressing ribosome and steroid biosynthesis. These results suggest that dmrt2a may contribute to testicular differentiation by coordinating chromatin remodeling and signaling integration. Overall, this study provides new insight into the evolution and potential functions of the dmrt gene family in C. semilaevis and identifies dmrt2a as a candidate regulator involved in pseudo-male differentiation and sex reversal in flatfish.
Chemodiversity of dissolved organic matter (DOM) is critical in greenhouse gas (GHG) dynamics in aquatic ecosystems, yet the mechanisms by which specific DOM components and biotic communities are associated with GHG flux variation in constructed wetlands (CWs) remain poorly understood. Here, we integrated ultrahigh-resolution DOM profiling, absolute bacterial quantification, vegetation surveys, and direct water-air GHG flux measurements across 39 field CWs spanning approximately 2700 km in China. We found that DOM chemodiversity was a stronger predictor of paired influent and effluent water-air GHG flux variation, expressed as FCO2-eq, than conventional environmental variables. Based on paired changes in FCO2-eq, CWs were classified into increased-flux CWs (ICWs) and decreased-flux CWs (DCWs), which showed distinct DOM transformation patterns. ICWs decomposed labile low-molecular-weight DOM stimulating higher GHG emissions, while DCWs were dominated by recalcitrant highly aromatic DOM associated with lower fluxes. Microbial diversity showed stronger associations with DOM chemistry and GHG flux patterns than plant diversity. Keystone bacteria such as Sphingomonas and Sphingopyxis dominated ICWs and promoted emissions, whereas Pseudarthrobacter and Micromonospora in DCWs favored carbon stabilization. Path analysis further verified that microbes exerted stronger effects than macrophytes (e.g., Canna indica or Phragmites australis) on DOM and GHG relationships. Our findings highlight the importance of DOM and bacterial community coupling in shaping water-air GHG flux variation in CWs, providing field scale evidence to support future CW design and management for water purification and climate mitigation.
Red tides pose a serious threat to ecological security and human health, making it critical to understand the proliferation mechanisms of toxic dinoflagellates such as Alexandrium pacificum. Given the limited transcriptional regulation in dinoflagellates, post-transcriptional mechanisms such as N6-methyladenosine (m6A) are likely key regulators. This study investigated the function of m6A in A. pacificum growth regulation. Treatment with the m6A inhibitor STM2457 significantly reduced overall m6A levels, which in turn suppressed algal cell growth and photosynthesis. To uncover the underlying molecular cascade, combined MeRIP-seq and RNA-seq analysis under different light intensities (200 vs 30 μmol photons/(m2·s)) was performed. Among 307 differentially m6A-modified genes, ApMETTL13 was identified as the top candidate, exhibiting the most pronounced increase in m6A modification and transcript expression; these results were validated by MeRIP-qPCR and RT-qPCR. Functional prediction and molecular docking suggested that ApMETTL13 may methylate lysine 55 of eukaryotic elongation factor 1A in A. pacificum (ApeEF1A), thereby regulating its activity. Further experiments indicated that, under high light, ApMETTL13-mediated m6A modification may promote K55me2 modification on ApeEF1A, potentially influencing the cell cycle and facilitating rapid algal growth. These findings reveal a potential epigenetic transcriptome-driven regulatory cascade, from RNA modification to protein expression, enzyme activity, and substrate modification, that may govern light-dependent growth in A. pacificum. The results provide precise data and potential targets for understanding dinoflagellate red tide dynamics and advance the functional knowledge of m6A modifications in marine algae.
Ferritin serves as both a regulator of iron homeostasis and an active participant in the innate immune response, playing multiple functions in immune defense, inflammation regulation, antioxidation, and immune protection. In this study, ferritin heavy chain (Fth) and medium chain (Ftm) were identified from Nile tilapia (Oreochromis niloticus) and characterized at both the expression and antibacterial functional levels. Both OnFth and OnFtm were widely distributed, occurring in all examined tissues. Notably, the recombinant OnFth protein significantly reduced the proliferation of Streptococcus agalactiae and Aeromonas hydrophila, whereas OnFtm exhibited no comparable antibacterial activity. Further analysis revealed that OnFth expression was significantly increased in the head kidney, spleen, liver, and intestine following bacterial challenge. Additionally, OnFth dampened inflammation, reduced pathological tissue damage, and improved the survival rate of tilapia upon bacterial challenge. Following OnFth knockdown, both tissue iron homeostasis and intestinal microecological stability were severely compromised in tilapia, accompanied by reduced host resistance against pathogenic bacterial infection. Mechanistic investigations revealed that OnFth knockdown inhibits the TGF-β1/Smad2/3 signaling pathway, which in turn reduces host resistance to bacterial infection. Moreover, zebrafish (Danio rerio) DrFth, an ortholog of OnFth also confers immune protection. Collectively, these results suggest that ferritin not only contributes to maintaining host iron homeostasis but also executes functions analogous to those of antimicrobial peptides, while remaining highly conserved during evolution. These findings also expand our understanding of the regulatory mechanisms underlying ferritin function in fishes and provide valuable insights into the evolution of innate immunity.
Effective monitoring is crucial for assessing biodiversity loss and detecting the early introduction of alien species, especially in freshwater ecosystems that are facing degradation at an alarming rate. However, traditional monitoring methods in lotic environments are often invasive, require specific expertise, and involve specimen handling that can lead to organism mortality. Emerging techniques, such as environmental DNA (eDNA) metabarcoding, offer a non-invasive alternative by generating biodiversity checklists from genetic material naturally shed by organisms. In this study, we applied eDNA metabarcoding to sample five strategic areas within the Serchio River basin, an understudied river system in Tuscany, central Italy, characterized by heterogeneous environments. Water samples were filtered, and eDNA was extracted from rivers of different sizes within each area. A total of 62 taxa were identified, encompassing both protected and invasive alien species representing the major vertebrate classes present in these rivers. Observed distribution patterns aligned with ecological expectations (i.e., known habitat preferences and longitudinal river zonation). Vertebrate biodiversity data obtained through eDNA were compared to efforts using traditional monitoring methods, including transect surveys conducted between March 2021 and October 2023 and electrofishing sessions. Across all areas, eDNA detected a higher number of species, including taxa not strictly associated with the river system, although both approaches identified some unique taxa. Taxa counts were generally higher in the mainstem than in smaller tributaries, suggesting that eDNA accumulates in main river branches. This finding underscores the potential of focusing on mainstem river courses for more efficient biodiversity monitoring at the basin scale. Through eDNA metabarcoding, we effectively characterized the Serchio River basin's biodiversity in a relatively short time compared to traditional methods, obtaining qualitative insights into the occurrences of both aquatic and terrestrial vertebrates, and capturing the gamma diversity of the area.
Blooms of Alexandrium catenella have affected coastal activities of the Northwestern Patagonia in the last 30-years, more particularly shellfish aquaculture, benthic fisheries and public health. These blooms have been associated with large-scale climatic anomalies such as positive phases of the El Niño Southern Oscillation (ENSO) and Southern Annular Mode (SAM). Nevertheless, their association with large-scale oceanographic anomalous conditions has been little studied. Here, we carried out for the first time a retrospective co-occurrence analysis of A. catenella blooms and Marine Heatwaves (MHWs), defined as anomalously warm temperature events observed in the ocean, over the 20 years period 2003–2023 in the Northwestern Patagonia. Our results reveal the important role of positive temperature anomalies and therefore MHWs in facilitating A. catenella blooms. Summers 2009, 2016, and 2018 stand out in terms of bloom intensities and MHWs, registering cell densities above 50 × 103 cells L−1 and the highest values were found in March 2009 with 3.4 × 105 cells L−1. These strong blooms were accompanied by strong temperature anomalies and MHWs, with events classified as Category III in 2009 and Category II in 2016. In contrast, low cell densities of A. catenella were detected in summer 2019 and 2020, attributed to unfavourable thermal conditions (either unstable or not strong enough), limiting the bloom proliferation. Overall, our results indicate that positive thermal anomalies and MHWs create favourable conditions for the initiation and intensification of A. catenella blooms in Northwestern Patagonia, although thermal forcing alone is not always sufficient to trigger bloom development.
The Paraopeba River, a major tributary of the upper São Francisco River in southeastern Brazil, has historically experienced intense anthropogenic pressure, including mining, urban sewage, and agricultural runoff. In January 2019, the collapse of the B1 tailings dam at the Córrego do Feijão mine released approximately 10 million m3 of mine waste, with an estimated 1.6 million m3 reaching the Paraopeba River, exacerbating existing environmental degradation. This study aimed to evaluate how the longitudinal gradients of water and sediment quality in the Paraopeba River have changed over five years (2019–2023) following the disaster. We measured physical and chemical parameters of water and sediment across 19 sites, encompassing the mainstem and tributaries. Using generalized additive models (GAMs), we evaluated the relative influence of space, seasonality, and time since impact on water and sediment quality, and how longitudinal patterns varied over the years of study. Our findings indicate that the sharp longitudinal gradients observed in 2019, especially for metals such as aluminium, iron and manganese, as well as turbidity, attenuated rapidly, becoming largely indistinguishable after 2021. Seasonal components progressively became the dominant drivers of variability, with rainfall-driven pulses governing the mobilization of sediments, nutrients, and residual contaminants. Meanwhile, tributaries with high urban and industrial influence, particularly the Betim River, emerged as persistent contributors to local degradation. In contrast, constituents such as magnesium and phosphorus exhibited more stable longitudinal structure, reflecting watershed-scale processes rather than disaster-related inputs. Sediment indicators (silt and sediment-bound arsenic) preserved a clearer imprint of the tailings through 2020 but also revealed diffuse and historical contamination upstream of the impacted reach. Overall, five years after the failure, the Paraopeba River exhibited a hybrid condition in which acute tailings impacts have largely dissipated from the water column, while chronic anthropogenic pressures and seasonal hydrology shape present-day spatial variability. These findings highlight the need for basin-wide management strategies that address ongoing pollution sources rather than focusing solely on post-disaster remediation.
Improving feed conversion efficiency (FCE) is critical for reducing the production costs and faecal waste in the aquaculture sector. However, the mechanisms that regulate FCE remain poorly understood. In this study, phylogenetic tree analysis revealed that the Rbmx protein encoded by the rbmx gene was highly conserved across different species and throughout evolutionary processes. The rbmx mRNA was widely expressed in various tissues of yellow catfish, with the highest expression levels in the liver and gonads. To further investigate the function of rbmx, we successfully established a stable rbmx knockout line in yellow catfish using CRISPR/Cas9 technology. Notably, we found that rbmx knockout significantly enhanced growth and FCE. Specifically, the body weight of rbmx+11 yellow catfish increased by 17.3% and 10.6%, while FCE improved by 20.2% and 17.8%, in males and females, respectively. Transcriptomic analysis further revealed that rbmx deficiency resulted in many differentially expressed genes (DEGs) that were enriched in growth and metabolism pathways. RT-qPCR analysis confirmed the upregulation of key genes involved in growth and metabolism pathways, such as ghra, pparg, and pygl. Taken together, our results demonstrate that rbmx is a negative regulator of growth and FCE in yellow catfish, further providing a theoretical foundation for precision molecular breeding (i.e., genome editing) for improving both growth and FCE in fish.
Ocean acidification (OA) and nanoplastics (NPs) increasingly co-occur in coastal ecosystems, yet their combined mechanistic impacts on calcifying invertebrates remain poorly resolved. Here, the mussel Mytilus coruscus was exposed for 30 days to factorial combinations of OA (pH 7.7 vs 8.1), surface-modified polystyrene NPs at a concentration of 100 μg/L (positively and negatively charged), and experimental shell damage to assess effects on shell repair, ion homeostasis, and energy metabolism. OA reduced shell repair quality by thinning repair layers, increasing porosity, and lowering calcium content, effects that were further enhanced by co-exposure to NPs, particularly negatively charged particles. OA and NPs jointly altered Ca2+ and Mg2+ levels, alkaline phosphatase activity, Ca2+Mg2+-ATPase activity, and key indicators of energy metabolism, including ATP content and cellular energy allocation. Transcriptomic and proteomic analyses revealed enrichment of ion transport, extracellular matrix, TGF-β signaling and other pathways, with divergent patterns linked to NPs surface charge. Together, these results suggest that nanoplastic surface charge under OA may impair mussel shell repair through associated alterations in ion homeostasis and energy metabolism. These findings highlight that particle surface properties shape how organisms respond to combined environmental stressors in acidifying marine environments.
Nitrite is a prevalent pollutant in global aquaculture systems that causes mass mortality in crustaceans through multisystem dysfunction. This study evaluated hepatopancreatic responses of Eriocheir sinensis to nitrite exposure (0, 2.5, 5, 10, and 20 mg/L) for 48 h, integrating histopathological, immunological, metabolic, and neuroendocrine analyses. Nitrite triggered dose-dependent biphasic regulation: haemolymph dopamine (DA) and crustacean hyperglycemic hormone (CHH) increased at low nitrite concentrations (2.5–5 mg/L) but decreased significantly at 20 mg/L, perturbing cAMP/cGMP/DAG second messengers and PKA/PKG/PKC kinases. The AMPK/CREB axis was activated at 5–10 mg/L but inhibited at 20 mg/L nitrite. Immune-antioxidant responses included reduced haemolymph hemocyanin, elevated hepatopancreatic malondialdehyde (MDA) (10–20 mg/L), suppressed SOD, CAT, PO, and LZM (20 mg/L), and transient ACP/AKP (peaking at 2.5–5 mg/L). Transcriptional-level analysis revealed that hsp90, lzm, alf3, and crustin were upregulated at 5 mg/L but downregulated at 20 mg/L. Metabolically, glycolysis enzymes (HK, PK) and genes (glut1, hk, g6p) were upregulated at 5–10 mg/L but suppressed at 20 mg/L, while lipid metabolism markers (FAS, CACT, pparγ, elovl6, fabp1, dgat1) revealed suppressed lipogenesis and enhanced fatty acid β-oxidation. These changes correlated with hyperglycemia-lactic acidosis, hypolipidemia, and decreased glycogen/ATP reserves. Partial least squares path modeling (PLS-PM) identified DA as the dominant regulator bridging neuroendocrine disruption to metabolic collapse. Our findings elucidate the integrated toxic mechanisms of nitrite in E. sinensis, providing critical insights for targeted health management in crab aquaculture.
Over the past two decades, hydrological connectivity in river systems has experienced rapid degradation globally. The loss of this connectivity has had adverse effects on aquatic environments. Consequently, biodiversity and food web structure are likely to be strongly associated with hydrological connectivity. Here, we investigated fish, benthic macroinvertebrates, benthic algae, and environmental data (e.g., river width, total phosphorus, and water temperature) were conducted in a river ecosystem in China, with food webs reconstructed using a meta-web approach to identify trophic interactions and assess the ecological cascades resulting from alterations in hydrological connectivity. Our results revealed that enhanced connectivity improved water conditions, such as higher flow rates and better aquatic habitat quality, along with lower water temperature and total phosphorus levels. These changes enhanced biodiversity metrics, including the species richness of fish, macroinvertebrates, and benthic algae communities. As a result, both the diversity (node count and number of intermediate species) and complexity (link number, linkage density, and connectivity) of aquatic food webs increased. Nonetheless, greater complexity in food web structure did not correspond to higher ecosystem functioning, such as improved resource utilization efficiency within the benthic algae community. Our findings suggest intrinsic correlations between hydrological connectivity and food web structures in aquatic ecosystems, thereby enhancing our understanding of ecological cascades in river ecosystems experiencing hydrological connectivity loss.
Mature sperms play a crucial role in fish reproduction, directly affecting offspring survival and quality. Cilia- and flagella-associated protein 58 (cfap58), localized to motile cilia, is essential for sperm flagellar assembly and male fertility. Defects of CFAP58 lead to severe multiple morphological abnormalities of the flagella (MMAF), exhibiting sperm flagellar malformations and motility impairments in mammals. However, current studies have mostly focused on mammals, with little known about fish. Here, we used zebrafish as a model organism to study the effect of cfap58 on fish fertility. Sperm carrying cfap58 mutations generated via CRISPR/Cas9 technology exhibited significantly reduced fertilization rate and embryo viability. Mutant sperm had abnormal flagella morphology, with the conserved “9 + 2” microtubule structure disrupted, abnormal mitochondrial morphology, and significantly reduced sperm motility. We also observed a significant increase in the proportion of undifferentiated germ cells in cfap58−/− testis. Single cell transcriptome sequencing of testis revealed that cfap58−/− showed extensive dysregulation of genes involved in multiple cilia and microtubule related pathways. Our data suggest that cfap58 plays an important role in sperm maturation and fertility maintenance in zebrafish. Additionally, we propose that cfap58 may participate in the composition of radial spokes and contribute to maintaining the normal function of intraflagellar transport (IFT) within the sperm flagellum.
In teleost fishes, TLRs are widely expressed in mucosal tissues and play crucial roles in host defense against pathogenic microbes, although the specific function of TLR1 in fish intestinal immunity remains poorly understood. In the present study, we generated TLR1 mutant Ctenopharyngodon idella (grass carp) using CRISPR/Cas9 technology and investigated the role of CiTLR1 in maintaining intestinal immune homeostasis and microbiota balance following Aeromonas hydrophila infection. We successfully generated F0 CiTLR1 mutant grass carp (CiTLR1-deficient) using CRISPR/Cas9. Following infection with A. hydrophila, CiTLR1-deficient fish exhibited exacerbated intestinal damage, reduced goblet cell abundance, and decreased IgT distribution and content in the intestinal mucosa compared to wild-type and negative control fish. qRT-PCR revealed that CiTLR1-deficient fish significantly downregulated key immune genes, including MyD88, IKKα, NF-κB1, TNF-α, IL6, IL22, MUC2, and Lysozyme, at 72 hpi. 16S rRNA sequencing revealed that CiTLR1 deficiency altered gut microbiota diversity, reduced beneficial bacteria (Cetobacterium and Barnesiellaceae), and enriched opportunistic pathogens (Vibrio, Pseudomonas and Crenobacter), with a marked increase in A. hydrophila abundance. These results indicate that CiTLR1 plays a critical role in maintaining intestinal immune homeostasis and microbiota balance, and its mutation compromises host defense against bacterial infection.
Cholesterol metabolism plays a significant role in regulating innate antiviral immunity during viral infection. However, the molecular mechanisms by which enzymes regulate the interferon signaling pathway are not well elucidated. Here, we investigated the potential function of the key enzyme in cholesterol synthesis, 3β-hydroxysteroid-Δ24 reductase (DHCR24), from grouper (EcDHCR24) during Singapore grouper iridovirus (SGIV) infection. Upon incubation with SGIV, the expression level of EcDHCR24 was significantly up-regulated in grouper spleen (GS) cells. Interestingly, EcDHCR24 overexpression significantly enhanced SGIV replication in GS cells, and inhibited the mRNA level of IFN-stimulated genes (ISGs) in vitro. Consistently, EcDHCR24 silencing exerted the opposite effects. EcDHCR24 overexpression also reduced the expression levels of these ISGs expression induced by sting, tbk1, irf3, and irf7. Furthermore, as an endoplasmic reticulum-localized protein, EcDHCR24 was found to interact with STING and TBK1. Mechanistically, EcDHCR24 enhanced the degradation of STING and TBK1 through the autophagy-lysosome pathway in a dose-dependent manner. Furthermore, it was worth noting that EcDHCR24 also interacted with toll-interacting protein (Tollip), and overexpression of EcTollip promoted EcDHCR24-medated degradation of STING and TBK1. Collectively, our findings revealed for the first time that fish DHCR24 negatively regulated interferon activation through Tollip-mediated autophagic degradation of the STING-TBK1 axis, and provided new insights into the mechanism by which DHCR24 regulates viral infection in fish.
The shortage of male broodstock is a major bottleneck that hinders the sustainable development of giant grouper (Epinephelus lanceolatus) industry, making effective male induction techniques a priority. However, developing effective male induction techniques remains elusive because the molecular basis of sex determination and gonadal development in this species is poorly understood. Here, we systematically characterize the molecular basis underlying gonadal differentiation of E. lanceolatus. We present a comprehensive atlas detailing the developmental trajectory of both primary males and females, showing that the species exhibits typical diandric protogynous hermaphroditism. Specifically, a critical window of primary sex reversal occurs at approximately two years of age, during which around 38.9% of individuals develop into primary males without reaching functional female maturation. RNA-seq analysis identified a key regulatory network composed of dmrt1, amh, gsdf, inha, and igf3, that is involved in male development. Additionally, the G protein-adenylyl cyclase signaling pathway was identified to play a crucial role in primary male differentiation. Using single-molecule fluorescence in situ hybridization, we revealed the co-localization of zbtb26 and dmrt1 mRNAs in both germline stem cells and gonadal somatic cells. Dual-luciferase reporter assay demonstrated that Zbtb26 directly activates the dmrt1 promoter in a dose-dependent manner. ChIP assay further supported that Zbtb26 can bind to the predicted motif-containing region of the dmrt1 promoter. These results indicate that Zbtb26 may directly promote dmrt1 transcription, thereby contributing to primary male sex determination. In summary, this study advances the understanding of diandric protogynous hermaphroditism in E. lanceolatus and provides a foundation for the development of male induction techniques for this species.
Carbonate alkalinity represents a primary constraint restricting the growth performance and nutrient utilization of aquaculture species in saline-alkaline waters. However, the specific physiological interplay by which this external chemical stressor disrupts metabolic homeostasis and uncouples the liver-gut axis remains poorly understood. This study combined physiological and histopathological assessments with integrated multi-omics analysis to elucidate the molecular drivers of growth retardation in Carassius auratus, a staple aquaculture species, under carbonate alkalinity stress. Chronic exposure to carbonate alkalinity resulted in significant growth inhibition in both the 1680 and 3360 mg/L NaHCO3 groups, while the 3360 mg/L NaHCO3 group exhibited more severe digestive impairment, as reflected by reduced lipase and amylase activities. Histopathological analysis revealed overt tissue damage, characterized by hepatic vacuolization with visible bile thrombi and gut mucosal atrophy. Physiologically, this was accompanied by a systemic collapse of serum lipid profiles (decreased triglycerides and total cholesterol) and a paradoxical increase in LDL-C. Integrated multi-omics analyses showed that carbonate alkalinity exposure was accompanied by a marked reduction in hepatic AE2 protein abundance, together with bile acid (BA) redistribution along the liver-gut axis. These changes were consistent with impaired bicarbonate-associated bile secretion and altered enterohepatic BA homeostasis. This secretory failure led to a depletion of luminal BAs, which consequently failed to trigger the negative feedback loop in the gut. This altered feedback pattern was associated with the paradoxical upregulation of hepatic BA biosynthesis-related enzymes (CYP8B1 and CYP27A1), driving a 15.7-fold (relative to the control group) intrahepatic accumulation of glycocholic acid. In the gut, reduced luminal BA availability was associated with lower abundance of lipid transport-related proteins (FATP4 and APOA1/4) and increased expression of the inflammatory mediator COX-2. Furthermore, the altered BA profile was associated with gut microbiota dysbiosis, characterized by Proteobacteria enrichment and Paenibacillus depletion. These findings suggest that AE2-associated BA transport dysfunction may represent an important mechanistic link connecting carbonate alkalinity stress with hepaticBA retention, gut BA depletion, and impaired lipid utilization. Collectively, these findings support a proposed model in which impaired enterohepatic BA homeostasis contributes to hepatic BA retention and gut lipid absorption dysfunction. Consequently, future nutritional intervention studies using exogenous BAs are warranted to test whether restoring BA homeostasis can improve metabolic resilience and production performance in saline-alkaline aquaculture.
Graphene oxide (GO), a carbon-based nanomaterial, has seen widespread application across various fields in recent years, resulting in its inevitable release into marine environments. However, the effects of GO on marine microbial communities remain poorly understood. This study utilized microcosm experiments and multi-omics approaches to assess the impact of GO on microbial communities in marine environments, focusing on community composition, diversity, co-occurrence network stability, and metabolic functions. The primary objective of this study was to evaluate the ecological risks posed by GO in marine ecosystems. The results indicate that GO exposure significantly altered the composition and diversity of marine microbial communities in a concentration- and time-dependent manner. A 7-day exposure to GO at concentrations of 1 mg/L and 5 mg/L led to a moderate increase in microbial diversity, whereas a 28-day exposure resulted in a reduction in diversity, particularly at concentrations ranging from 1 to 10 mg/L. Additionally, 28-day exposure decreased the complexity and stability of co-occurrence networks, with network stability becoming more reliant on keystone taxa under high-concentration conditions (5 and 10 mg/L). GO exposure also shifted microbial community composition, enriching taxa such as Roseobacter, Roseivivax, Lentimonas, and Phaeobacter under 28-day exposure conditions. Metagenomic analysis revealed that prolonged exposure to GO significantly altered the abundance of key functional genes (e.g., frmA, cooS, metF, ppdk, mdh, nrtA, narG, nirS, norC, dsyB, and dmdA), enhancing metabolic pathways related to carbon, nitrogen, sulfur, and methane cycling. Notably, GO exposure promoted denitrification processes, suggesting an increased risk of N2O production. In contrast, metabolic pathways associated with the cell cycle, photosynthesis, and membrane transport were downregulated at higher GO concentrations. Overall, these findings demonstrate that the introduction of GO into marine environments poses ecological risks by altering microbial community structure and function, with potential implications for biogeochemical cycles. They highlight the necessity for stricter regulation and monitoring of GO discharge into marine ecosystems.
Plastic debris in marine and freshwater ecosystems has become a growing global concern, negatively impacting aquatic life and human health. The worldwide challenge of persistent macro-litter, which originates from various origins and is conveyed by rivers to the oceans, has significant biological, chemical, and ecological impacts on oceanic environments. Plastic contamination is a critical ecological issue that can cause a variety of adverse effects on ecosystems. Its presence affects organisms in both water and soil, significantly threatening the stability of these natural systems. This work aims to advance unmanned aerial vehicles (UAVs), remote sensing (RS), and machine learning (ML) methods for litter tracking and cleanup support, promoting ecological protection and waste reduction. AI-powered tools, such as camera- and sensor-equipped UAVs (drones), enable real-time monitoring of microplastics (MPs) contamination across ecosystems. AI approaches (e.g., ML) have greatly improved the performance and accuracy of observing MP sources and forecasting contamination levels. These solutions reduce the requirement for human engagement and simplify the decision-making procedure. Significantly, more advanced algorithms (e.g., YOLOv12) are needed to assess the migration trends of plastics into the ecosystem. This advancement indicates promoting AI's ability to control current pollution and mitigate additional environmental degradation. The protocol facilitates large-scale comparative studies, promoting integrated coastal management efforts at both international and national levels.
