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PubMed2026

Long-term heat exposure reshapes muscle molecular regulation and enhances thermal tolerance in Clarias fuscus.

Rapid fluctuations in water temperature driven by global warming have become a major abiotic stressor affecting muscle function in teleost fish. This study examined the effects of long-term thermal conditions on heat tolerance in Clarias fuscus. Fish were maintained for 90 days at either a normal temperature group (NT, 26 °C) or a high-temperature group (HT, 34 °C). Subsequently, muscle histology, and transcriptomic profiles were observed following acute high-temperature exposure (34 °C) and after temperature recovery (26 °C). Histological analysis showed that fish from the NT under acute high-temperature stress exhibited severe muscle damage (atrophy, myofilament disruption, and myolysis), whereas fish from the HT displayed markedly reduced lesions. RNA-seq profiling revealed 5769 differentially expressed genes (DEGs) in the NT and 3292 DEGs in the HT following acute temperature challenges. Functional enrichment indicated that, in the HT, modulation of key cell cycle regulators (e.g., ccna, ccnb, cdk1, cdk2) contributed to alleviating muscle damage caused by temperature fluctuations. In the NT, genes associated with ribosome biogenesis (e.g., nop56, riok2, riok1) were up-regulated and then down-regulated during temperature fluctuation, whereas p53 in the cell cycle pathway showed the opposite expression pattern. These findings demonstrate long-term heat exposure reshapes molecular expression and regulatory mechanisms in the muscle of C. fuscus, thereby enhancing thermal tolerance and adaptability, and providing a theoretical basis for breeding heat-resistant, high-quality aquaculture strains.

Animals↗

PubMed2026

Dynamic evolution of chaperone-mediated autophagy is associated with tumor microenvironment remodeling and prognostic stratification in lung adenocarcinoma: insights from single-cell transcriptomics, ensemble machine learning, and experimental validation.

BACKGROUND: Lung adenocarcinoma (LUAD) shows prognostic heterogeneity, and tumor-node-metastasis (TNM) staging is limited for individualized management. Chaperone-mediated autophagy (CMA) maintains proteostasis, but its role during adenocarcinoma in situ (AIS)-minimally invasive adenocarcinoma (MIA)-invasive adenocarcinoma (IAC) progression remains unclear. METHODS: Single-cell RNA sequencing (scRNA-seq) data from GSE189357 and bulk transcriptomes from The Cancer Genome Atlas (TCGA)-LUAD and Gene Expression Omnibus (GEO) cohorts were integrated. CMA activity, cell-cell communication, weighted gene co-expression network analysis (WGCNA), tumor-normal differential expression, machine-learning survival modeling, tumor microenvironment (TME) features, drug sensitivity, and EPC1 function were analyzed. RESULTS: CMA-high tumor epithelial cells increased from AIS (58.1%) to MIA (65.7%) but declined in IAC (44.4%; p < 0.001). CMA-low cells preferentially received fibroblast-derived extracellular matrix cues. A CMA-negatively correlated module identified 69 core genes. Random survival forest (RSF) performed best among 117 machine-learning combinations (mean concordance index > 0.873). High-risk patients had worse survival across cohorts, and the risk score was independently associated with overall survival (hazard ratio = 16.013, 95% confidence interval: 9.579-26.768, p < 0.001). High-risk tumors showed proliferative activation and M0 macrophage enrichment, whereas low-risk tumors showed stronger immune-related signaling. EPC1 overexpression suppressed malignant phenotypes in A549 cells. CONCLUSION: CMA dynamics are associated with stromal and immune remodeling during LUAD progression. A CMA-based model provides robust prognostic stratification and may offer a basis for future TME-guided studies.

Chaperone-mediated autophagy↗

PubMed2026

Comparative transcriptomic analysis of the gills and hepatopancreas of freshwater-cultured Litopenaeus vannamei under chronic nitrite stress.

To investigate the differences in molecular responses between the gills and hepatopancreas of freshwater-cultured Litopenaeus vannamei under chronic nitrite stress, a 30-day chronic stress experiment was conducted with a control group and a stress group. Transcriptomic analysis of the gills and hepatopancreas was performed using Illumina sequencing; differentially expressed genes (DEGs) were identified, and GO, KEGG, GSEA, PPI, and RT-qPCR validation were carried out. The results showed that 196 DEGs (161 up-regulated and 35 down-regulated) were identified in the gills, and 287 DEGs (199 up-regulated and 88 down-regulated) in the hepatopancreas, with only 18 DEGs shared between the two tissues. DEGs in the gills were enriched in oxidoreductase activity, glycerophospholipid metabolism, and tyrosine metabolism; DEGs in the hepatopancreas were enriched in lipid transporter activity, phagosome, ECM-receptor interaction, and riboflavin metabolism. GSEA revealed significant suppression of the mTOR pathway in the gills and the Polycomb complex pathway in the hepatopancreas. PPI network analysis identified hub genes P5CS and eEF2 in the gills, and PER, TUBB1, SHMT, and TUBB4B in the hepatopancreas. RT-qPCR validation was consistent with the RNA-seq results (R2 = 0.764). This study indicates that, under chronic nitrite stress, the gill response is centered on redox regulation and inhibition of growth metabolism, whereas the hepatopancreas response primarily involves lipid transport, cytoskeletal remodeling, and phagosome activation. The two tissues synergistically adapt through fundamental biosynthetic and motor protein pathways. This research provides molecular evidence for deciphering the nitrite tolerance mechanisms in freshwater-cultured shrimp.

Animals↗

PubMed2026

Evaluating the pathogenic significance of unique chromosomal variants in craniosynostosis using patient-derived induced pluripotent stem cells and mouse modelling.

PURPOSE: Unravelling causal links between unique structural/copy-number variants (SV/CNV) and associated phenotypes is essential for correct genetic counselling. We investigated two families in which patients with craniosynostosis had SV/CNV potentially dysregulating a fibroblast growth factor (FGF)-encoding gene; a 730 kb dup(4)(q21.21) including FGF5; and a complex 568 kb interspersed 13q12.11 duplication, located 841 kb from FGF9. METHODS: We combined bioinformatic predictions of altered topologically-associating domain (TAD) structure, with experimental analysis (RNA- and ATAC- [assay for transposase-accessible chromatin] sequencing) of patient induced pluripotent stem cell lines (iPSCs) differentiated to neural crest (NCC) and osteoprogenitor (OPC) identities. For the dup(4)(q21.21) we generated a mouse bearing an equivalent rearrangement using CRISPR-Cas9 targeting. RESULTS: TAD analysis suggested potential dysregulation of the FGF5/FGF9 gene by bringing it into a novel genomic milieu. The RNA- and ATAC-seq assays demonstrated FGF5/FGF9 upregulation (2.7-18x) and local opening of chromatin, in 3/4 cell lines. For the dup(4)(q21.21), a causal role was supported by the mouse model, whereas interpretation of the 13q12.11 SV is confounded by a co-existing FOXP2 pathogenic variant. CONCLUSION: Patient iPSC-differentiated NCC and OPC lines, combined with TAD-based modelling to generate testable functional hypotheses, provide valuable functional evidence when evaluating causation of unique SV/CNV in craniosynostosis.

copy-number variant↗

PubMed2026

ATF4-histone 2-hydroxyisobutyrylation feedback loop drives sepsis-induced inflammation.

BACKGROUND AND PURPOSE: The role and mechanisms of lysine 2-hydroxyisobutyrylation (Khib) in the acute inflammatory phase of sepsis remain unclear. We investigated the function and underlying mechanisms of histone H4 lysine 5 2-hydroxyisobutyrylation (H4K5-hib) in sepsis-induced inflammation in vivo and in vitro. EXPERIMENTAL APPROACH: Acute sepsis was induced by caecal ligation and puncture (CLP) in mice, and inflammatory responses were modelled in lipopolysaccharide (LPS)-stimulated macrophages. CUT&Tag-seq was used to identify genomic targets associated with H4K5-hib and activating transcription factor 4 (ATF4). Immunofluorescence, Western blotting, qPCR, dual-luciferase assays, and ELISA were performed to investigate the underlying mechanisms. KEY RESULTS: H4K5-hib levels were increased in macrophages during the acute inflammatory phase of sepsis. LPS stimulation enhanced H4K5-hib enrichment at the ATF4 promoter, thereby promoting ATF4 transcription. Inhibition of EP300-mediated 2-hydroxyisobutyrylation or mutation of H4K5 abolished ATF4 activation. Increased H4K5-hib activated the ATF4/NLRP3 signalling axis, promoting inflammasome assembly and amplifying inflammatory responses. ATF4 directly bound to the EP300 promoter and enhanced its transcription, forming a positive feedback loop that further increased H4K5-hib levels. In CLP-induced sepsis, pharmacological inhibition of EP300 or ATF4 reduced H4K5-hib levels and suppressed NLRP3 inflammasome activation. CONCLUSION AND IMPLICATIONS: These findings reveal a previously unrecognized epigenetic mechanism underlying sepsis-induced inflammation and identify the EP300/ATF4/H4K5-hib positive feedback loop as a potential therapeutic target for sepsis.

Animals↗

PubMed2026

Ribosome stalling position, spacing, and A-site occupancy impact translation and cotranslational mRNA decay in plants.

Ribosomes can pause during mRNA translation, but what causes pausing, how pauses affect protein production, and whether they trigger cotranslational mRNA decay are poorly understood in plants. Here, we investigate the causes and consequences of ribosome pausing in Arabidopsis and maize. This is accomplished by sizing, mapping, and quantifying footprints of individual ribosomes (monosomes) and closely spaced ribosome pairs (disomes) at single-codon resolution on open reading frames (ORFs). Ribosome footprinting was combined with 5'P-degradome-seq to examine the coincidence of pausing with cotranslational decay under control conditions and brief hypoxia in Arabidopsis. The data resolve two monosome conformations and three disome configurations. These include monosomes with a vacant or occupied A-site and disomes that have collided or are separated by one or two codons. Pausing is prevalent at initiation, termination, and di-Proline codons. Di-Proline pauses do not trigger cotranslational decay but appear important in cotranslational protein processing. Brief hypoxia induces stalling of A-site vacant ribosomes at Aspartate codons, often coinciding with 5'P peaks, indicating that rate-limiting decoding can trigger cotranslational mRNA decay. Notably, actively transcribed and translated hypoxia-response mRNAs accumulate 1- to 2-codon-separated disomes and are actively degraded. Comparative analysis of footprints in the two species reveals ribosome conformations and codon-specific pausing can be conserved or lineage-specific, as exemplified by pausing at di-Prolines and on Conserved Peptide upstream ORFs. In sum, the stalling of ribosomes at specific codons, coupled with ribosome A-site occupancy and disome spacing, modulates protein production and cotranslational mRNA decay in plants.

Ribosomes↗

PubMed2026

Distinct molecular responses to acute cold exposure revealed by comparative transcriptomic and metabolomic profiling in the bay scallop Argopecten irradians.

Acute cold stress can elicit distinct molecular responses even when bay scallop populations show similar phenotypic outcomes. We compared a seventh-generation fast-growing bay scallop line (BS) with a commercial control population (CC) during a 72-h acute cold exposure at -1 ± 0.3 °C. RNA-seq was used as the discovery layer, representative BS cold-responsive genes were evaluated by qRT-PCR, and paired LC-MS profiles provided a comparative metabolic layer. At baseline, 138 genes differed between BS and CC; after cold exposure, 134 of these baseline differences disappeared and 61 of 65 cold-state differences newly emerged. BS showed a larger transcriptomic response magnitude than CC, with 1129 cold-responsive genes compared with 28 genes in CC, and this ordering remained robust across multiple sensitivity analyses. Survival after 72 h was identical in BS and CC (83/90, 92.2% in each population). Biochemical responses were time-dependent and marker-specific: CAT, LZM, T-SOD and T-AOC showed population-by-time interactions, whereas GSH-Px and MDA did not, and the 72-h differences were not consistently favourable to BS. Metabolomic cold effects were strongly concordant between populations, and no feature showed a significant population-by-cold interaction. Features putatively assigned to arachidonic acid metabolism were enriched, but this provider-annotated pathway signal remains exploratory because authentic-standard confirmation was not performed. These findings indicate population-specific differences in molecular responsiveness but do not establish superior cold tolerance in BS.

Animals↗

PubMed2026

Mineral-driven molecular signatures of energy metabolism underpin sperm motility in buffalo.

The success of spermatogenesis depends on the interplay of various biomolecules that ultimately determine sperm quality. In this study, RNA-seq analysis of frozen-thawed buffalo sperm (n = 8) revealed the presence of 263 mineral-associated genes (>1 FPKM) in high (n = 4) and 181 in low motile (n = 4) sperm groups. Among these, 177 mineral-associated genes were commonly expressed between them, and the majority were upregulated (>1 fold), LOC102391588 (ncRNA; 37-fold), ZNF699 (26.5-fold), MYZAP (13-fold), etc., in the high motile group. The expression of selected mineral-associated genes was validated. The top enriched functions in commonly expressed genes were regulation of transcription by RNA polymerase II (FDR: 4.7 × 10⁻2; ZNF331, ZNF692, ZNF180, etc.), followed by spermatogenesis (FDR: 2.9 × 10⁻2; CALR3, ADAM18, ADAM29, etc.), proton transmembrane transport (FDR: 4.0 × 10⁻2; ATP6V0E1, ATP1A4, ATP6V1B2, etc.) and flagellated sperm motility (FDR: 2.3 × 10⁻1; CATSPERD, EFCAB6, CABS1, etc.). Additionally, the chromatin remodeling pathway (FDR: 3 × 10⁻2; PTP4A1, PPM1A, DUSP1, etc.) emerged as the most significant and may suggest that these minerals influence genome packaging and sperm functionality. Mineral-associated genes were predominantly associated with zinc (49%), followed by calcium (20%), phosphorus (10%), iron (5%), sodium (2%), potassium (2%), copper (1%) and other trace elements (11%). Although the current study uses frozen-thawed sperm, the findings indicate that mineral-associated genes are crucial for promoting membrane stability, energy production, motility and chromatin integrity, which may contribute to the superior fertilizing ability of sperm.

Animals↗

PubMed2026

Integrative machine learning and transcriptomic analysis reveals molecular mechanisms underlying low survival rate in larval Chinese Bahaba (Bahaba taipingensis).

Chinese Bahaba (Bahaba taipingensis) is a Class I protected marine fish endemic to China. Low larvae survival during artificial breeding severely hinder population recovery. To investigate the molecular mechanism of high mortality in larval fish, this study performed RNA-seq on liver from naturally deceased (ND) and mass-dead (MD) individuals, combined with least absolute shrinkage and selection operator (LASSO) regression and random forest (RF) algorithms to screen for core signature genes. A total of 873 differentially expressed genes (DEGs) were identified, including 112 upregulated and 761 downregulated genes. GO and KEGG enrichment analyses revealed significant enrichment in amino acid metabolism disorders, one‑carbon folate pool impairment, PPAR signaling abnormalities, ECM-receptor interaction, focal adhesion pathway, indicating widespread metabolic suppression accompanied by extracellular matrix remodeling and signaling disturbances in the livers of MD fish. MAD pre-filtering combined with dual machine learning algorithms yielded 18 robust core signature genes, among which SLC38A4, MMP1, FADD, FKBP5, and APOB were consistently identified as high-frequency core genes by both algorithms. SLC38A4 exhibited the highest importance score in the RF model and was significantly downregulated, making it the primary molecule distinguishing ND from MD phenotypes. ROC curve analysis showed that both models achieved an AUC of 1.000 (95% CI lower bound: 0.610), confirming the precise discriminatory ability of the core genes. GSEA further demonstrated significant enrichment of this core gene set in ND samples. This study provides the first systematic elucidation of the molecular mechanisms underlying liver dysfunction in low survival rate B. taipingensis, characterized by amino acid transport impairment, metabolic reprogramming, and structural remodeling, offering theoretical foundations for health assessment, early mortality risk warning, and artificial breeding conservation of this species.

Animals↗

PubMed2026

Prioritizing Parkinson's disease risk-associated mitochondrial candidate genes via multi-omics integrative analysis.

BACKGROUND: Mitochondrial dysfunction has been implicated in Parkinson's disease (PD), but the genetically regulated mitochondrial genes associated with PD risk remain incompletely defined. METHODS: We conducted a summary-data-based genetic epidemiology study integrating summary-based Mendelian randomization (SMR), Heterogeneity in dependent instruments (HEIDI) filtering, and Bayesian colocalization to prioritize mitochondrial-related molecular features associated with PD risk. Mitochondrial-related genes were defined using MitoCarta3.0. Genetically predicted gene expression and plasma protein abundance were evaluated using expression quantitative trait loci (eQTL) data from eQTLGen and GTEx v8, and protein quantitative trait loci (pQTL) data was assessed using International Parkinson's Disease Genomics Consortium (IPDGC) as the discovery genome-wide association study (GWAS) and FinnGen as the replication dataset. Prespecified QTL analyses were interpreted using FDR correction, HEIDI filtering, and colocalization support. DNA methylation QTL analysis, mitochondrial phenotype MR, and single-nucleus RNA-seq analysis were performed as complementary analyses. RESULTS: In the primary eQTL analysis, higher genetically predicted TTC19 expression was associated with lower PD risk (OR = 0.80, 95% CI: 0.74-0.87, PPH4 = 0.80), whereas higher MALSU1 expression was associated with increased PD risk (OR = 2.21, 95% CI: 1.59-3.06, PPH4 = 0.96). Both associations survived FDR correction, passed HEIDI filtering, and showed colocalization support. GTEx whole-blood data supported the direction of the TTC19 association. No mitochondrial protein reached significance after FDR correction and colocalization filtering in the primary pQTL analysis. Complementary methylation analysis highlighted cg06270993 as an exploratory regulatory signal for MALSU1. CONCLUSIONS: This MR-colocalization study prioritizes TTC19 and MALSU1 as genetically supported mitochondrial-related candidate genes associated with PD risk. Further validation is required to define their functional roles in PD pathogenesis.

Humans↗

PubMed2026

Comparative phylogenomics and transcriptional regulatory networks of AQPs, HSPs, and LEA proteins in salt-stressed Portulaca oleracea.

Soil salinization severely threatens global food security, necessitating systematic investigations of halophytes like Portulaca oleracea to decode the molecular mechanisms of environmental resilience. Utilizing an integrated framework of deep learning-based genome annotation (58,817 predicted genes; 96.5% BUSCO completeness), multi-tissue RNA-Seq, phylogenomics, and gene regulatory network (GRN) inference, the synergistic orchestration of 78 aquaporins (AQPs), 525 heat shock proteins (HSPs), and 119 late embryogenesis abundant (LEA) proteins was elucidated. The active transcriptome, encompassing 39,065 expressed loci, revealed a systemic growth-defense trade-off. Tissues displayed distinct adaptive mechanisms: leaves modulated intracellular water balance via specialized AQPs, whereas adult roots maintained proteostasis through robust HSP20/HSP70 induction. Phylogenomic clustering across 154 species demonstrated that salinity tolerance constitutes an evolutionary mosaic, identifying 81 halophyte-exclusive orthogroups and 1129 species-specific clusters. Comparative topology across six independent GRNs (4.2M-5.3 M edges) unmasked a highly modular transcriptional reprogramming strategy governed by a core apparatus of 22 stress-exclusive regulators, with functional enrichment heavily prioritizing protein dimerization and chromatin remodeling. Theoretically, the distinct convergence of Trihelix transcription factors with guard cell differentiation pathways offers a candidate transcriptomic framework to explain the plant's characteristic C4-CAM photosynthetic plasticity under severe osmotic pressure. Practically, these evolutionary blueprints and specific master switches transcend single-gene transgenic limitations. Utilizing these root-sustained and stress-inducible targets under localized promoters provides a naturally optimized, network-level precision engineering roadmap to transfer robust, compartmentalized halotolerance to sensitive glycophytic crops.

Gene Regulatory Networks↗

PubMed2026

METTL14-mediated m6A modification of CCNE1 accelerates progression of myelodysplastic syndromes via MAPK-ERK and PI3K-AKT signaling pathways.

BACKGROUND: N6-methyladenosine (m6A) is the most common RNA modification and plays a key role in the initiation, progression, and relapse of multiple cancers, including hematologic malignancies. However, the role of m6A and m6A regulatory genes in myelodysplastic syndromes (MDS) remains unclear. This study aims to elucidate the function and molecular mechanism of methyltransferase METTL14 in MDS. METHODS: RT-qPCR was used to assess the expression of multiple m6A regulators, focusing on METTL14 in MDS patients and cell lines. METTL14 overexpressing and knockdown cell lines were established, and CCK-8, EdU, and flow cytometry assays were performed to explore the biological functions of METTL14.Dot blot, MeRIP-Seq, MeRIP-qPCR, RT-qPCR, and Western blot were employed to investigate the underlying molecular mechanism. RESULTS: Dysregulation of multiple m6A regulators was observed in MDS, among which METTL14 was upregulated. Elevated METTL14 expression increases MDS risk and adverse prognosis, emerging as a biomarker for poor prognosis. METTL14 promoted proliferation and cell-cycle progression of MDS cells while inhibiting apoptosis; corresponding changes were observed in cell cycle and apoptosis markers. METTL14 regulated cellular m6A levels. Downstream targets of METTL14 were enriched in cell cycle-related pathways, with CCNE1 identified as a critical target. Knockdown of METTL14, actinomycin D, or S-adenosylhomocysteine treatment reduced CCNE1 mRNA and protein levels. Furthermore, METTL14 activated MAPK-ERK and PI3K-AKT signaling via CCNE1 in an m6A-dependent manner, thereby promoting proliferative MDS cells' capacity. CONCLUSIONS: This study delineates a METTL14/m6A/CCNE1 signaling axis in MDS progression and suggests that METTL14-mediated m6A modification may be a potential therapeutic target for MDS.

Humans↗

PubMed2026

Transcriptomic responses of gill and intestinal tissues in Nile tilapia (Oreochromis niloticus) to bacterial infection following sequential nanoimmersion and hydrogel-based multivalent vaccination.

Bacterial pathogens, including Flavobacterium oreochromis, Aeromonas veronii, Streptococcus agalactiae, and Edwardsiella tarda, represent major infectious threats to Nile tilapia (Oreochromis niloticus). A multivalent vaccination strategy integrating cationic nanoemulsion immersion with oral hydrogel boosters was developed to investigate tissue-specific immune responses at the transcriptomic level. Gill tissues were collected following immersion challenge and intestinal tissues following intraperitoneal injection challenge, reflecting the physiologically relevant infection biology of each pathogen and the mechanistic rationale of each delivery platform. RNA sequencing (RNA-seq) generated high-quality datasets (mapping rate > 81.64%) with strong concordance to quantitative real-time PCR (qRT-PCR) validation (r = 0.83). Comparative transcriptomic analysis revealed distinct yet complementary immune signatures between tissues. Gill transcriptomes were enriched in phagosome, focal adhesion, extracellular matrix-receptor interaction (ECM-receptor interaction), and cytokine-cytokine receptor interaction pathways, accompanied by increased expression of major histocompatibility complex class I/II (MHC class I/II), mannose receptor, αVβ3 integrin, and calnexin, indicating innate activation, enhanced phagocytic capacity, epithelial barrier reinforcement, and adaptive immune coordination. Intestinal transcriptomes showed predominant enrichment of adaptive immune pathways, including the intestinal immune network for immunoglobulin (Ig) production, Forkhead box O (FoxO) signaling, and mitogen-activated protein kinase (MAPK) signaling, with increased expression of T-cell receptor (TCR), inducible T-cell co-stimulator ligand (ICOS-L), C-X-C chemokine receptor type 4 (CXCR4), and polymeric immunoglobulin receptor (pIgR), reflecting T and B cell coordination, lymphocyte trafficking, and mucosal immunoglobulin transport, alongside innate engagement through phagosome pathway enrichment. Shared upregulation of MHC class II, B-cell receptor (BCR) signaling, integrin alpha M (ITGAM), and immunoglobulin-associated components across both tissues suggests coordinated mucosal immune activation through a conserved immune module, warranting direct experimental validation. Collectively, these findings provide transcriptomic evidence that this vaccination strategy elicits an integrated, tissue-specialized immune response, advancing mechanistic understanding of gill and intestinal immunity in vaccine-induced protection of teleost fish.

Animals↗

PubMed2026

Multi-omics integrative analysis provides insight into potential molecular responses to sustained high water flow in common carp (Cyprinus carpio) cultured in recirculating aquaculture.

To investigate the potential molecular responses by which water flow intensity affects the growth of common carp (Cyprinus carpio) in a recirculating aquaculture system (RAS), a control group (CG, actual water velocity 0.3 cm/s) and three sustained flow treatment groups were established, including a low-flow group (LF, 1 body length per second, bl/s), a medium-flow group (MF, 2 bl/s), and a high-flow group (HF, 3 bl/s). After 12 weeks of culture in the RAS, growth performance was compared among groups under different flow intensities. The best-performing group and the control group were then selected for the determination of intestinal digestive enzyme activities, as well as transcriptomic and whole-genome bisulfite sequencing analyses of muscle tissue. The results showed that the specific growth rate and feed intake of the HF group were significantly higher than those of the other groups (P < 0.05), whereas no significant difference in feed conversion ratio was observed among groups. Compared with the CG group, lipase activity was significantly higher in the HF group (P < 0.05), while α-amylase and trypsin activities showed increasing trends without significant differences. RNA-seq identified a total of 273 differentially expressed genes, including 72 upregulated genes and 201 downregulated genes in the HF group relative to the CG group. These genes were mainly enriched in glycolysis, pyruvate metabolism, ATP metabolism, the pentose phosphate pathway, the insulin signaling pathway, the PPAR signaling pathway, and the adipocytokine signaling pathway, indicating that sustained high water flow induced a muscle transcriptional response characterized by remodeling of energy metabolism and substrate utilization. Whole-genome bisulfite sequencing analysis showed that DNA methylation in common carp muscle occurred predominantly in the CpG context. Differentially methylated regions between the HF and CG groups were mainly distributed in transcription-related regulatory regions, including promoters, CpG islands, and CpG island shores. In promoter regions, the number of hypermethylated regions in the HF group relative to the CG group was markedly higher than that of hypomethylated regions. Integrated analysis further identified two candidate genes showing both promoter differential methylation and differential expression, namely LOC109094644 and bcorl1, suggesting that adaptation to high water flow may involve IGF-related growth regulation and remodeling of upstream transcriptional programs. The qPCR results were consistent with the transcriptomic data. Taken together, within the tested range, a sustained water flow of 3 bl/s was more conducive to the growth of common carp in the RAS, which may be associated with enhanced lipid digestion and utilization, remodeling of the muscle energy metabolic network, changes in promoter methylation, and the coordinated regulation of key candidate genes. This study provides a theoretical basis for clarifying the exercise adaptation mechanism of common carp in recirculating aquaculture and for optimizing flow velocity parameters.

Animals↗