Search Results (145)

Large yellow croaker (Larimichthys crocea) is an economically important marine fish species in China, yet regional variation in its gut microbial community structure and functional characteristics remains insufficiently understood. This study aimed to characterize and compare the gut microbiota of farmed large yellow croaker across five representative aquaculture regions. Intestinal microbial communities were characterized using 16S rRNA gene sequencing, followed by analyses of microbial diversity, taxonomic composition, predicted bacterial phenotypes, co-occurrence networks, and environmental associations. The five cultured populations shared a broadly similar microbial community structure dominated by Proteobacteria, Bacteroidota, and Firmicutes, whereas the relative abundance of several dominant taxa varied among regions. Alpha-diversity differences were mainly associated with community evenness and dominance rather than estimated richness. Although regional samples partially overlapped in ordination analyses, the aquaculture region explained 41.4% of the variation in gut microbial composition, indicating significant region-associated differentiation. Predicted microbial characteristics were comparatively similar among cultured populations, despite variation in taxonomic composition, while microbial network organization also differed across regions. Environmental variables showed clearer associations with water microbiota than with gut microbiota, and local aquaculture water represented a detectable but limited potential source of intestinal microorganisms. Overall, farmed large yellow croaker maintained a shared gut microbial community structure but exhibited region-associated variation in community composition and predicted bacterial phenotypes. These findings provide a regional baseline for understanding gut microbial variation in farmed large yellow croaker under different aquaculture conditions. Full article

Bigels combine the advantages of hydrogel and oleogel matrices, enabling simultaneous encapsulation of both hydrophilic and lipophilic compounds with good ductility and water retention. Bigels were prepared from large yellow croaker myofibrillar protein (MP)–soybean oil oleogels and κ-carrageenan hydrogels. All the bigels exhibited a milky white, solid-like self-supporting structure. Increasing the oleogel fraction enhanced droplet interactions and uniformity. Hardness peaked at 11.67 g at a 5:5 (w/w) oleogel-to-hydrogel ratio. The rheological tests revealed shear-thinning behavior across all samples, with apparent viscosity increasing progressively with oleogel content. The highest thixotropic recovery (71.07%) was observed at an oleogel-to-hydrogel ratio of 6:4 (w/w). All bigels underwent structural destabilization above 40 °C and complete liquefaction above 60 °C, indicating thermal reversibility. This study elucidates how varying the oleogel-to-hydrogel ratio modulates the physicochemical properties of bigels, providing a theoretical basis for developing high-value products from large yellow croaker. Full article

Large yellow croaker (Larimichthys crocea) is an economically important marine fish, yet rapid and non-destructive discrimination between sea-caught and farmed collection-source groups remains challenging. This study developed a fish-level analytical workflow integrating YOLO11n-seg instance segmentation with visible–near-infrared hyperspectral imaging to extract relative reflectance ratios from six anatomical regions. The analytical cohort comprised 258 unique fish, including 171 sea-caught and 87 farmed individuals. Source categories were assigned according to the original capture or cage-culture collection channels. Fish identity was used as the grouping unit in five-fold internal cross-validation, and classification performance was evaluated based on out-of-fold fish-level predictions. Logistic-regression models achieved AUC values ranging from 0.985 to 1.000 across the six individual anatomical regions. The combined six-region model achieved an accuracy of 0.996 (95% CI, 0.988–1.000) and an AUC of 1.000 (95% CI, 1.000–1.000) within the present cohort. For anatomical-region segmentation, the 20-image validation set contained 140 annotated instances. Bounding-box precision, recall, mAP@0.5, and mAP@0.5–0.95 were 0.976, 0.983, 0.981, and 0.700, respectively, while the corresponding mask metrics were 0.969, 0.976, 0.972, and 0.669. These results indicate that region-specific hyperspectral information can support highly accurate internal discrimination between the two collection-source groups and provide an interpretable basis for characterizing source-associated spectral differences. However, the source labels were not independently verified, potentially influential covariates were incompletely recorded, and no independent external cohort was available. Therefore, the present findings should be interpreted as internally validated collection-source discrimination rather than verified provenance authentication or evidence of external generalizability. Full article

Visceral white-nodules disease (VWND), caused by Pseudomonas plecoglossicida, poses a severe threat to the large yellow croaker (Larimichthys crocea) aquaculture industry. Although breeding resistant strains is a promising strategy, the molecular basis of disease resistance in this host remains poorly understood. Here, 1500 fish were artificially infected, and extreme phenotypes (30 resistant, RL; 30 susceptible, SL) were selected based on survival time and liver pathogen load. Liver histopathology revealed that RL fish maintained intact architecture with only mild vacuolation, whereas SL fish exhibited widespread necrosis, inflammation, and hemosiderin deposition. Consistently, RL fish showed lower MDA levels and higher GSH-Px activity and TAC. Transcriptomic analysis identified 172 differentially expressed genes (DEGs): RL fish were characterized by upregulation of anti-inflammatory and tissue-protective genes (Epo, CAV3) and downregulation of pro-coagulant factors (PAI1, K1kb1). Proteomic analysis identified 111 differentially expressed proteins, with significantly enriched pathways including the peroxisome, pentose phosphate, and phagosome pathways. Integrated cross-omics analysis revealed eight co-enriched KEGG pathways; among them, arginine/proline metabolism, phagosome, oxidative phosphorylation, and focal adhesion were consistently upregulated in the RL group. These findings suggest that effective resistance to VWND in L. crocea may involve a coordinated, multi-layered defense program encompassing redox balance, regulated immune responses, metabolic reprogramming, and cellular homeostasis. Cross-omics-supported candidate factors (e.g., P4ha1, COX6B, RAB5A, CAV3) represent promising targets for functional validation via DNA-level experiments in independent sample sets, and the prominent enrichment of arginine-proline metabolism indicates a potential target for dietary intervention that merits further investigation. Full article

Shansha Bay, southeastern China, is a typical semi-enclosed bay facing intense anthropogenic pressure, with mariculture production reaching approximately 660,000 tons annually, predominantly driven by the large yellow croaker (Larimichthys crocea) industry. To assess how these pressures influence biodiversity detection, we employed eDNA metabarcoding targeting the 12S rRNA gene to survey fish diversity across 10 sites, integrating both surface water and sediment matrices. A total of 40 species belonging to 16 orders, 27 families and 32 genera, were identified. Among them, L. crocea, Bostrychus sinensis, Clupanodon thrissa and Siganus fuscescens are the dominate species, which comprised over half of all OTUs. Comparison with historical trawl surveys revealed 30 newly recorded species, including the Japanese eel (Anguilla japonica) and oarfish (Regalecus glesne). Alpha diversity was low (Shannon: 0.69–1.93), with significant spatial disparities driven by freshwater runoff and hydrodynamics. While eDNA effectively captured the dominance of cultured species like L. crocea, the extreme biomass signal poses challenges for detecting wild populations. Our findings underscore that a multi-matrix eDNA approach is crucial for accurate biodiversity assessments in aquaculture-dominated coastal ecosystems, although distinguishing wild stocks from aquaculture-derived DNA remains a critical methodological hurdle. Full article

Large yellow croaker (Larimichthys crocea) is an economically important mariculture species in China, but marked individual variation in body weight reduces production uniformity. To explore molecular features underlying this phenotypic divergence, liver tissues from high-weight and low-weight fish from the Naozhou population were subjected to integrated transcriptomic and untargeted metabolomic analyses. A total of 3390 DEGs were identified in the high-weight group (HWG) compared with the low-weight group (LWG), including 1576 upregulated and 1814 downregulated genes. Functional annotation indicated that the DEGs were predominantly associated with pathways governing cell-cycle progression, DNA synthesis and replication, lipid turnover, and amino acid-related metabolic processes. Untargeted metabolomic profiling identified 2263 annotated metabolites, of which 241 were differentially accumulated between the two groups. Pathway enrichment indicated that these altered metabolites were primarily associated with lipid-related processes, amino acid turnover, and cellular energy metabolism. Integrated analysis further revealed significant correlations between DEGs and differential metabolites and highlighted several co-enriched pathways, including linoleic acid metabolism, biosynthesis of amino acids, carbon metabolism, and fatty acid biosynthesis. These findings provide preliminary evidence that body-weight differences in large yellow croaker may reflect coordinated changes at both the transcriptomic and metabolomic levels, with lipid metabolism, amino acid metabolism, and energy-related pathways being particularly involved. As an exploratory study, these results should be regarded as candidate molecular associations that require further validation in larger populations before being applied to breeding or nutritional regulation. Full article

The rapid expansion of aquaculture breeding has increased the need to identify wild genetic resources for germplasm management and sustainable breeding. However, distinguishing wild from domesticated populations remains challenging in species with recent domestication histories and low genetic differentiation. In this study, we used the large yellow croaker (Larimichthys crocea) as a case study species to develop specific insertion/deletion (InDels)-based identification methods for wild and domesticated populations based on whole-genome resequencing data. Four large-fragment InDels with significant allelic frequency differences between populations were selected as one marker panel. In addition, four coding-region InDels predicted to alter amino acid sequences were selected as another marker panel based on allele-frequency differences, coding-region annotation, and supporting SNP-based Fst or nucleotide-diversity signals. Principal component analysis (PCA) based on these selected InDel loci showed partial separation with some overlap between wild and domesticated samples. Therefore, multi-locus scoring models were established by assigning scores to wild-predominant alleles. Receiver operating characteristic (ROC) analysis showed strong discriminatory performance for both panels, with area under the ROC curve (AUC) values of 0.9608 and 0.9771 and classification agreement rates with known sample status of 90.0% and 91.7%, respectively. These results indicate that targeted InDel markers can provide a practical PCR-based approach for distinguishing wild and domesticated large yellow croaker populations with limited genetic differentiation. This workflow may provide a reference for marker development in other recently domesticated species, although further validation in independent populations and target species is needed. Full article

Microbial communities associated with fish mucosal tissues play important roles in host health and environmental adaptation. However, the effects of contrasting aquaculture conditions on the microorganisms of the large yellow croaker (Larimichthys crocea, L. crocea) remain poorly understood. In this study, 16S rRNA gene sequencing was used to compare the gut and gill microbiota of L. crocea cultured in a marine system and a saline–alkaline system, together with the corresponding surrounding water samples. The results showed that both host tissue type and rearing environment significantly influenced microbial community structure. Water samples generally exhibited higher alpha diversity than host-associated samples, whereas the gut and gill communities were clearly separated from the surrounding water microbial community. The intestine showed stronger culture system differentiation than the gill, suggesting greater niche selectivity, while the gill retained a closer association with the rearing water. Across multiple taxonomic levels, microbial composition differed markedly among water, gut, and gill samples, and the divergence between the marine culture and saline–alkaline culture system became more pronounced at finer taxonomic resolution. Differentially enriched taxa further revealed clear tissue- and habitat-associated microbial patterns. In addition, several dominant taxa were significantly correlated with environmental variables, especially salinity and nutrient-related factors, indicating that physicochemical heterogeneity contributed substantially to microbial community assembly. Overall, this study shows that host mucosal niche and rearing environment are associated with distinct gut and gill microbiota patterns in L. crocea and provides preliminary ecological information for future microbiome-informed aquaculture management, functional validation of candidate taxa, and the development of land-based culture systems for marine fish. Full article

Background: The visual system plays critical roles in fish feeding, predator avoidance, and reproduction, with the phototransduction pathway serving as the core molecular mechanism of visual signal transduction. This study represents the first systematic analysis of phototransduction-related genes in large yellow croaker (Larimichthys crocea). Methods: Bioinformatics, transcriptomic analysis, and RT-qPCR were used to identify phototransduction-related genes in large yellow croaker and analyze their developmental expression patterns and responses to different light spectra. Results: Thirty phototransduction-related genes were identified, including genes involved in light perception, signal amplification, and signal termination and recovery. Structural analyses indicated that these genes were highly conserved in teleosts. Most genes showed low expression during 1–7 days post-hatching (dph), increased expression during 7–24 dph, and stable expression during 24–35 dph. Collectively, these results identify 15–24 dph as a critical developmental window for visual system maturation in large yellow croaker larvae. Under different spectral treatments at 15 dph, phototransduction-related genes exhibited wavelength-dependent expression patterns. Under the present experimental conditions, relatively higher expression levels of most phototransduction-related genes were observed under blue- and green-light treatments, whereas relatively lower expression levels were observed under the red-light treatment. Key downstream genes, including gucy2f, guca1d, calml4a, and rgs9b, were significantly affected by different light spectra. Conclusions: This study revealed the developmental dynamics and spectral response characteristics of phototransduction-related genes in the large yellow croaker. These findings provide new insights into teleost visual development and light adaptation and provide a molecular basis for future studies aimed at optimizing light conditions during larval rearing in large yellow croaker aquaculture. Full article

Visceral white spot disease caused by Pseudomonas plecoglossicida poses a severe threat to large yellow croaker (Larimichthys crocea) aquaculture. This study investigated the immunomodulatory effects and underlying mechanisms of Pseudostellaria heterophylla extract against P. plecoglossicida infection in L. crocea. Fish were fed a basal diet supplemented with 1% P. heterophylla extract for 30, 45, and 60 days, followed by intraperitoneal injection with 200 μL P. plecoglossicida (1 × 10⁴ CFU/mL). When the control group reached about 50% mortality, transcriptome sequencing of head kidney tissues was performed on the 45 and 60 days post-feeding of the treatment groups to analyze gene expression changes following bacterial infection. Survival rates of the treatment groups were 33.33%, 13.33%, and 20% higher than those of the control group at 30, 45, and 60 days post-feeding, respectively. Transcriptomic analysis revealed time-dependent transcriptional responses: in one group, 45 days post-feeding, 10 differentially expressed genes (DEGs) were identified (2 up-regulated and 8 down-regulated), whereas in another group, 60 days post-feeding, 893 DEGs were detected (417 up-regulated and 476 down-regulated). Functional enrichment analysis (GO, KEGG, and GSEA) demonstrated that DEGs were significantly enriched in immune-related pathways, including Toll-like receptor signaling, chemokine activity, Th1 and Th2 cell differentiation, hematopoietic cell lineage, and cytokine–cytokine receptor interaction. Key immune genes, including chemokines, Toll-like receptors, and T cell regulators, were significantly up-regulated. These findings indicate that P. heterophylla extract enhances both the specific and non-specific immune capabilities of L. crocea in a time-dependent manner, with prolonged supplementation eliciting more robust transcriptional activation of immune defense pathways. This study provides a scientific foundation for developing immunological prevention strategies against P. plecoglossicida infection in aquaculture. Full article

Various immunostimulants have been employed to enhance the efficacy of aquaculture. However, the mechanisms by which Eucommia ulmoides extracts affect the pathogen resistance of large yellow croakers remain to be elucidated. In this study, a multi-omics investigation was conducted to investigate the potential for enhancing pathogen resistance and to elucidate the underlying mechanisms of Eucommia ulmoides extracts on large yellow croaker juveniles. It revealed that the survival rate of the large yellow croaker juveniles was significantly enhanced (approximately doubled) by oral extracts of Eucommia ulmoides in the context of pathogen invasion. Examining the transcriptome of the liver revealed that Eucommia ulmoides extracts have the capacity to activate the class I MHC pathway for antigen processing, including genes for HSP70, HSP90, CALR, TAPBP, MHCI, and TCR. This, in turn, facilitates the phagocytosis of pathogens by the immune system. Furthermore, the alpha-diversity of the large yellow croaker juveniles’ gut microbiota was increased by the Eucommia ulmoides extracts, maintaining the stability of the gut microbiota and reducing the ratio of pathogens (Burkholderia cenocepacia and Streptococcus iniae) following a pathogen challenge. The application of correlation analyses indicated that a reduction in pathogens was closely associated with variations in whole gut microbiota. Full article

Dual-specificity phosphatase 5 (DUSP5) is a negative regulator of mitogen-activated protein kinase (MAPK) signaling and has been implicated in inflammation and immune regulation. However, its role in teleost fish remains incompletely understood. In this study, DUSP5 from large yellow croaker (Larimichthys crocea), designated as LcDUSP5, was characterized with respect to its molecular features, tissue distribution, subcellular localization, and transcriptomic associations following transient overexpression in macrophages. The full-length open reading frame (ORF) of LcDUSP5 is 1131 bp and encodes a 376-amino-acid protein containing a conserved rhodanese homology domain and a dual-specificity phosphatase catalytic domain. LcDUSP5, was broadly expressed in the examined tissues, with the highest expression in the liver. Subcellular localization analysis showed that LcDUSP5 was predominantly localized in the nucleus. A transient overexpression model was established in the large yellow croaker head kidney-derived macrophage cell line LM10, and samples collected at 24 h post-transfection were subjected to transcriptome sequencing. A total of 365 differentially expressed genes were identified, including 283 up-regulated and 82 down-regulated genes. GO and KEGG enrichment analyses suggested that these genes were associated with pathways related to endocytosis, chemokine signaling, phagosome function, calcium signaling, and lipid metabolism. These results provide the first characterization of DUSP5 in large yellow croaker combined with transcriptomic analysis of macrophage responses and suggest that LcDUSP5 may be associated with immune-related pathways in teleost macrophages. Full article

Although mass-spawning pooling systems are widely used for small yellow croaker (Larimichthys polyactis) aquaculture, they often induce severe genetic bottlenecks driven by reproductive skew. This study evaluated cross-generational genetic diversity and spawning patterns to propose an optimal genetic management strategy. We analyzed 1049 adult broodstock and 950 juvenile offspring using nine microsatellite markers. To mitigate reproductive skew, fertilized eggs were collected via multi-time sampling (19 times) over a two-month spawning season and reared to the juvenile stage. Genetic diversity was highly conserved across generations, with expected heterozygosity maintained at 0.860 in the offspring. Parentage assignment succeeded for 96.2% of the offspring (914 individuals), revealing 802 unique families, of which 89.9% (721 families) were singletons. Also, 60.9% of the broodstock contributed to reproduction, exhibiting a right-skewed participation distribution. Importantly, comparisons with a short-term single-event collection control group demonstrated that our multi-time strategy effectively prevented drastic reductions in effective population size (N_e). These patterns highlight the species asynchronous spawning physiology and confirm that the strategy approximates random mating with minimal genetic drift. We suggest this long-term, multi-time egg collection method as an effective protocol for the sustainable genetic management of multiple-spawning marine fish. Full article

Accurate measurement of antigen-specific antibody responses is essential for evaluating antibody avidity and quantification. Traditional. Enzyme-Linked Immunosorbent Assay (ELISA), while widely used, is limited by lengthy procedures, dependence on secondary antibodies, and inconsistent reproducibility. In this study, biolayer interferometry (BLI) was established and validated for simultaneous quantification and avidity assessment of specific IgM in serum of Larimichthys crocea (Large yellow croaker) using Pseudomonas plecoglossicida outer membrane protein Omp-H as antigen. Sera from immunized and control fish were analyzed by both BLI and ELISA, with systematic comparison between platforms. Optimal serum dilutions were 1:128 for BLI and 1:1024 for ELISA. Validation with another outer membrane protein, Omp-W, confirmed the method’s broad applicability. BLI association signals and avidity indices correlated strongly with ELISA values, yielding consistent results for both antigens. BLI successfully captured specific antibody responses in infected sera and demonstrated superior inter-plate reproducibility compared to ELISA, which exhibited significant inter-plate variation. However, BLI required lower serum dilutions (hence larger volumes) to achieve comparable sensitivity. These findings establish BLI as a rapid, single-step method providing reliable quantitative and avidity data for teleost IgM, offering a reproducible alternative to ELISA with potential applications in vaccine evaluation and aquaculture infection detection. Full article

The excessive accumulation of biogenic amines (BAs) in aquatic products poses serious health risks, necessitating the development of rapid and sensitive detection methods. This study reports the synthesis of a novel fluorescent nanocomposite, carbon-dot-embedded covalent organic frameworks (CDs@COFs). Comprehensive characterization (TEM, XPS, FTIR, UV–Vis, and fluorescence spectroscopy) confirmed the successful fabrication of the nanocomposites, which exhibited excellent thermal and optical stability. A significantly enhanced quantum yield of 36.22% (compared with 12.92% for pure carbon dots) was obtained. As a fluorescent probe, the composite enabled the detection of nine BAs based on a fluorescence quenching mechanism. The proposed method demonstrated good linearity (1~100 ng/mL) and low detection limits of 0.58~0.98 ng/mL. The method was successfully applied to analyze tyramine in large yellow croaker, showing accurate spike recoveries ranging from 91.93% to 101.43% and excellent reproducibility (RSD < 3%). These results highlight the great potential of the developed method as a powerful tool for the rapid screening of BAs in aquatic products. Full article