Using a three-factor orthogonal design, we investigated the transcriptomic and histological responses of triploid rainbow trout (Oncorhynchus mykiss) gills across three salinities (10, 20, and 30 ppt) over 60 days, with temperature and body size as background conditions. Results showed that 20 ppt was associated with extensive transcriptional reprogramming, with 3333 differentially expressed transcripts (DETs), whereas 30 ppt induced only 120 DETs; WGCNA further identified salinity-correlated modules involved in ion transport and ribosome biogenesis. Histological alterations remained within physiological ranges with no salinity-dependent severity gradient, as confirmed by semi-quantitative scoring. These findings demonstrate that triploid rainbow trout gills employ distinct molecular strategies at medium versus high salinity. Within the 10–30 ppt range examined, 20 ppt was the salinity at which transcriptional reprogramming was most active, suggesting that this intermediate salinity warrants further investigation as a potential acclimation stage.

The hard clam Meretrix meretrix is a commercially important bivalve species in China, yet its aquaculture industry is increasingly threatened by germplasm degradation and recurrent mass summer mortality events associated with elevated temperatures and Vibrio infections. To characterize candidate germplasm resources with potential value for heat-tolerance breeding and to elucidate the genetic basis of adaptive differentiation, we integrated genotyping-by-sequencing (GBS) and gill transcriptome sequencing across five wild populations spanning the entire latitudinal range of China: Dandong (LD), Weihai (SW), and Rudong (JR) in the north, and Beihai (GB) and Qinzhou (GQ) in the south. Phylogenetic and population structure analyses resolved the five populations into two distinct genetic lineages corresponding to northern and southern clusters, with the Beihai population exhibiting the highest genetic diversity and the Weihai population showing signs of inbreeding that were elevated relative to the other populations. Comparative transcriptomic analysis revealed that differentially expressed genes between northern and southern populations were significantly enriched in immune-related pathways (including NOD-like receptor and IL-17 signaling pathways) and lipid metabolic pathways (including cholesterol and steroid biosynthesis). Notably, populations with similar genomic backgrounds still displayed pronounced transcriptional divergence, indicating that transcriptional divergence can arise even in the absence of strong genomic differentiation; because this conclusion is based on observational data, it cannot fully separate long-term genetic adaptation from environmentally induced transcriptional plasticity. These findings provide fundamental data for germplasm conservation and for future selective breeding programs targeting stress resistance in M. meretrix.

Marine biofouling by sessile invertebrates such as Diadumene lineata poses a persistent threat to marine infrastructure, and antifouling agents are critical for mitigating this issue, yet their molecular mechanisms of action on fouling cnidarians remain poorly understood. In this study, acute toxicity tests and 24 h attachment inhibition assays were conducted, followed by transcriptomic sequencing of pedal disc tissue from D. lineata exposed to N-oleyl-1,3-propanediamine. The 96 h-LC₅₀ of the agent was determined to be 38.66 mg/L, and exposure to 70 mg/L agent achieved complete 24 h attachment inhibition. Transcriptomic analysis identified extensive transcriptional perturbations across four core physiological systems: metabolic reprogramming via activated PPAR signaling, immune dysregulation characterized by impaired antigen processing and DAMP-mediated inflammation, disrupted post-transcriptional regulation and proteostasis, and compromised axon regeneration with decoupled damage sensing and repair. Collectively, these interconnected disruptions synergistically impaired the structural integrity, energy supply, and stress adaptation capacity of pedal disc cells, ultimately leading to adhesion inhibition in D. lineata. This study clarifies the multi-pathway toxic mechanism of antifouling agents in fouling sea anemones, providing a foundational molecular framework for future research.

This study combined acute toxicity assays, phenotypic quantification, and transcriptomic profiling to systematically investigate the inhibitory effects and molecular regulatory mechanisms of a novel alkylamine-based antifouling agent on survival, byssus secretion, and attachment behavior of juvenile Mytilus edulis. The 96 h-LC50 of the agent to juvenile M. edulis was 8.84 mg/L, and 10 mg/L of the agent completely inhibited mussel attachment within 24 h, significantly reducing byssal thread number, length, and diameter while increasing detachment frequency, resulting in irreversible attachment failure. Transcriptomic analysis identified 2746 differentially expressed genes, which were mainly enriched in pathways including signal transduction, immune defense, stress response, cytoskeleton organization, and protein binding. KEGG and GSEA enrichment revealed that the antifouling agent activated the MAPK stress signaling pathway, disturbed transcriptional regulation, and impaired intracellular homeostasis and cytoskeletal stability, thereby synergistically suppressing the expression of key byssal protein genes including mfp-1 and mfp-3 and ultimately blocking byssus synthesis and adhesion. This study clarifies the multi-pathway molecular mechanism underlying antifouling agent-induced attachment inhibition in M. edulis, and provides core molecular targets and theoretical support for developing efficient, low-toxicity, and eco-friendly marine antifouling technologies.

Marine biofouling by sessile invertebrates such as Diadumene lineata poses a persistent threat to marine infrastructure, yet the molecular mechanisms by which industrial chemicals affect fouling cnidarians remain poorly understood. In this study, we combined acute toxicity and attachment inhibition assays with transcriptomic sequencing of the pedal disc—the primary adhesive organ—of D. lineata following exposure to the industrial corrosion inhibitor N-oleyl-1,3-propanediamine. The 96 h-LC50 was determined to be 38.66 mg/L, and 70 mg/L exposure achieved complete attachment inhibition within 24 h. Transcriptomic analysis identified 2,913 differentially expressed genes (DEGs), predominantly upregulated (62.0%), which were enriched in PPAR signaling, antigen processing and presentation, systemic lupus erythematosus, microRNAs in cancer, and axon regeneration pathways. Gene set enrichment analysis (GSEA) revealed coordinated downregulation of ribosome and translation-related gene sets alongside upregulation of cilium and axoneme-associated terms. Transcription factor analysis showed predominant upregulation of HSF, bZIP, and zinc finger C2H2 families, with mixed regulation of Homeobox and bHLH families. SNP and SSR analyses revealed no substantial genomic alterations between groups. Integration of phenotypic and transcriptomic data supports a multi-pronged mechanism whereby the compound disrupts cytoskeletal adhesion machinery, impairs protein quality control and clearance, and induces a metabolically costly stress response, collectively rendering the pedal disc incapable of maintaining firm substrate attachment. These findings establish a foundational transcriptomic framework for understanding cnidarian responses to industrial corrosion inhibitors and provide insights relevant to ecological risk assessment in marine environments.

Rainbow trout (Oncorhynchus mykiss) is a globally important cold-water aquaculture species, yet the molecular events underlying the transition from embryo to free-living larva remain poorly resolved. In this study, eukaryotic reference-based transcriptome sequencing was used to compare genome-wide gene expression profiles between eggs (eyed-egg stage) and newly hatched larvae of O. mykiss. A total of 618 differentially expressed genes (DEGs) were identified, of which 297 were upregulated and 321 downregulated. Gene Ontology (GO) enrichment analysis showed that DEGs were significantly enriched in immune system process, response to stimulus, and biological regulation. Within the immune system process category, 4 DEGs were upregulated and 11 were downregulated in larvae, indicating a more complex remodelling of immune-related gene expression than simple activation. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis identified only Glycolysis/Gluconeogenesis (map00010) as significantly enriched (padj < 0.05). Nitrogen metabolism (map00910) and tryptophan metabolism (map00380) showed enrichment trends but were not statistically significant after multiple-testing correction. Because these pathways contained only a small number of DEGs and displayed mixed regulation, no overall pathway-level up- or down-regulation was inferred. These results suggest a possible metabolic remodelling during the transition from yolk-dependent anabolism to catabolic utilization in larvae. Transcript assembly further identified 134,770 potential novel isoforms and 2902 intergenic transcripts classified as putative novel transcripts, enriching the genome annotation of O. mykiss. Trend clustering indicated coordinated regulation of immune and stress-response genes together with downregulation of amino acid and energy metabolism genes, revealing programmed temporal regulation during this developmental transition. These findings provide foundational data for understanding early development in rainbow trout and candidate molecular targets for health-oriented aquaculture management.