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Are there any common effects in preclinical models of micro- and nanoplastic (MNP) exposure? A systematic review.

Micro- and nanoplastics (MNPs) are emerging contaminants detected in food sources and the marine food chain, raising concerns about human health. Although no causal relationship has been established between MNP exposure and specific diseases, growing evidence suggests adverse developmental, behavioral, cognitive and biochemical effects. This systematic review synthesized evidence from common preclinical neurotoxicology models, including C. elegans, D. rerio, D. melanogaster, in vitro systems and rodents, to identify convergent developmental, behavioral and biochemical outcomes. The protocol was preregistered in OSF, followed PRISMA-P guidelines, applied PICOS criteria, and assessed methodological quality using the European Commission's ToxRTool. Overall, 185 studies were included. Consistent findings showed impaired survival and disrupted development across all models. Behavioral alterations affecting anxiety, memory, learning, sociability and locomotor activity were also consistently reported. In addition, numerous studies identified disruptions in the serotonergic (5-HT) system, including changes in neurotransmitter levels, transporters and metabolic enzymes. Despite methodological heterogeneity, these findings indicate that MNP exposure produces reproducible neurodevelopmental and neurochemical alterations across experimental models. Future studies should improve methodological harmonization, strengthen cross-model comparability and identify robust biomarkers and key mechanisms underlying MNP-induced neurotoxicity, facilitating translation to human health risk assessment frameworks.

Animals

A case report of Xp21 contiguous gene deletion syndrome with adrenal crisis and sensorineural hearing loss: clinical highlights and management pitfalls.

OBJECTIVES: To report a rare association of Xp21 contiguous gene deletion syndrome (CGDS) featuring sensorineural hearing loss (SNHL), and to discuss the diagnostic and therapeutic challenges. CASE PRESENTATION: A male infant presented with a salt-wasting adrenal crisis consistent with X-linked adrenal hypoplasia congenita. His follow-up clinical course during childhood revealed global developmental delay and SNHL, the latter of which has been under-reported in the literature for this condition. At five years of age, the development of progressive proximal muscle weakness and markedly elevated creatine phosphokinase levels led to a diagnosis of Duchenne muscular dystrophy (DMD). The patient also exhibited pseudohypertriglyceridemia and elevated urinary glycerol, consistent with glycerol kinase deficiency. While initial exome sequencing failed to detect the genetic abnormality, subsequent chromosomal microarray analysis identified an Xp21 CGDS involving NR0B1, IL1RAPL1, DMD, and GK. Treatment of adrenal insufficiency with fludrocortisone and hydrocortisone was complicated by the higher steroid doses required for the management of DMD, resulting in exogenous Cushing syndrome and associated complications. CONCLUSIONS: This case highlights the necessity of evaluating for Xp21 CGDS in patients presenting with adrenal crisis and emphasizes the importance of multidisciplinary management to optimize outcomes in this complex pediatric endocrine disorder.

Humans

The spatial and temporal distribution of Staphylococcus aureus along a tropical Hawaiian watershed.

Staphylococcus aureus is a leading cause of community-acquired skin and soft-tissue infections worldwide. One major route of exposure is recreating in marine waters, but knowledge is limited regarding the drivers of S. aureus in surface waters that discharge into marine environments. This study explores spatial and temporal distributions of S. aureus, including antimicrobial-resistant and virulence genes, using both culture-dependent and molecular techniques across a tropical Hawaiian watershed with a gradient of human influence. Negative binomial generalized linear mixed models revealed that the interaction between spatial and temporal factors was the strongest predictor of S. aureus and associated genes. Cultured S. aureus was highest at mid-watershed sites in summer, which included a popular swimming hole, suggesting human shedding as a significant source. Molecular detection of S. aureus (femA gene) yielded concentrations two orders of magnitude higher than cultured concentrations and peaked at estuarine sites with the greatest nutrients and water residence times. In the winter at upstream sites with no public access, staphylococci antibiotic-resistant (mecA) and S. aureus virulence gene (etb) were elevated, indicating highly pathogenic S. aureus strains in surface waters may originate from zoonotic sources. Our findings indicate that human and zoonotic sources contribute antibiotic-resistant and virulent S. aureus to watersheds, with streams facilitating environmental transmission to marine waters. This watershed-scale assessment enables the prediction of spatial and temporal conditions associated with elevated S. aureus concentrations, thereby reducing exposure and infections.

Staphylococcus aureus

Integrative multi-omics reveals a fibroblast-centered, ZFHX3-prioritized regulatory framework linking sick sinus syndrome and atrial fibrillation.

OBJECTIVE: To define shared genetic and multi-scale mechanisms underlying comorbidity between sick sinus syndrome (SSS) and atrial fibrillation (AF). METHODS: We integrated genome-wide association study (GWAS) summary statistics for SSS and AF with Genotype-Tissue Expression (GTEx) expression and splicing quantitative trait loci (eQTL/sQTL), atrial single-cell and spatial transcriptomics, and epigenomics. We identified trait-relevant tissues and pathways, prioritized shared cell types, quantified genome-wide and local genetic sharing, detected joint loci by cross-trait meta-analysis, and linked loci to regulatory programs via colocalization and cell-prioritized co-expression networks. RESULTS: Both traits showed strongest enrichment in cardiac tissue, especially Heart Atrial Appendage. Fibroblasts from the left atrial appendage were consistently prioritized as the key shared cell population. SSS and AF displayed significant positive genome-wide genetic correlation, with multiple locally shared regions, including six major loci. Cross-trait meta-analysis identified eight joint-phenotype SNPs implicating four susceptibility genes. ZFHX3 was the leading tissue-cell-gene candidate, acting as a hub in fibroblast co-expression modules and colocalizing with cardiac regulatory signals. CONCLUSION: Shared liability for SSS and AF is highly tissue- and cell-specific, converging on regulatory networks in atrial appendage fibroblasts, with ZFHX3 serving as a central mechanistic and biomarker node.

Humans

[Optical genome mapping analysis of a Chinese pedigree with a complex balanced translocation involving four chromosomes].

OBJECTIVE: To explore the genetic characteristics of a complex balanced translocation involving four non-homologous chromosomes in a Chinese pedigree using optical genomic mapping (OGM). METHODS: A woman with primary infertility and her family members who presented at the Prenatal Diagnosis Center of the Sixth Affiliated Hospital of Sun Yat-sen University in October 2021 were selected as study subjects. Comprehensive analysis and verification of chromosomal abnormalities were conducted through conventional G-band karyotyping analysis, single nucleotide polymorphism microarray (SNP array) and OGM. This study was approved by the Medical Ethics Committee of the hospital (Ethics No.: E2022210). RESULTS: G-band karyotyping analysis indicated that the proband, her father, and younger brother have all carried a complex translocation involving four chromosomes. SNP array analysis revealed a duplication of approximately 21.63 Mb in the 9p24.1-p21.1 region in the proband's younger brother, while no abnormality was detected in other family members. OGM confirmed that the complex balanced translocation has involved chromosomes 5, 8, 9, and 10. CONCLUSION: The proband has harbored a complex balanced translocation. OGM has demonstrated certain advantages in characterization of complex chromosomal structural abnormalities.

Humans

Influence of nicotine on protein expression around hydrophilic osseointegrated implants: A proteomic study in male rats.

OBJECTIVE: To ensure the success of dental implant treatment, various factors must be considered, including osseointegration and systemic conditions. There is evidence in the literature that smokers may exhibit alterations in tissue healing, which can compromise the success of implant rehabilitation. Therefore, this study aimed to investigate the influence of nicotine on the protein profile of bone tissue around hydrophilic implants during the osseointegration process in rats. DESIGN: Bone tissue samples from the control and nicotine groups (n = 3 per group) were subjected to protein extraction, mass spectrometry, and bioinformatic analyses. Protein identification was performed using Proteome Discoverer 2.1 software and the SEQUEST algorithm, and the protein data were compared with those of a protein database of Rattus norvegicus obtained from UniProt. RESULTS: A total of 740 proteins were detected in both the control group and the nicotine-exposed group. Among them, the proteins biglycan, periostin and histone H4 were highlighted because of their higher abundance in the healthy implant group, while they were reduced in the nicotine-exposed group. CONCLUSIONS: Nicotine has the potential to alter the protein profile of bone tissue around hydrophilic implants during osseointegration, which may impair tissue remodeling and healing.

Animals

Genetic Diversity Analysis of Red Fox Populations (Vulpes vulpes L., 1758) in Natural and Anthropogenic Isolation.

This study presents a comparative analysis of the genetic structure and diversity of three red fox (Vulpes vulpes L.) populations representing different microevolutionary scenarios: panmixia (free-ranging Belarusian foxes), geographic isolation (free-ranging Scottish foxes), and anthropogenic selection (farm-bred foxes). Using a validated set of STR markers, multivariate statistical analysis was conducted to assess the genetic structure and the degree of genetic erosion across the studied groups. The wild red fox population in Belarus has been shown to maintain a state close to panmixia (PHWE = 0.090), characterized by a high effective population size (Ne = 694) and high allelic diversity. The island population from Scotland exhibits moderate gene pool depletion (Ne = 75.9) and a pronounced heterozygote deficiency (FIS = 0.18). Critical genetic erosion, which was characterized by a minimal effective population size (Ne = 60.2) and allelic fixation, was detected in the farm-bred group. The genetic distance between farm-bred and wild foxes (FST = 0.279; p = 0.001) reflects both the phylogeographic divergence between the Nearctic ancestors of farmed lineages and Palearctic wild populations, and the consequences of prolonged anthropogenic isolation, genetic drift, and selective breeding. These data indicate that artificial isolation and the impacts of genetic drift and targeted selection lead to a substantial depletion of the species' adaptive potential.

Animals

Analyzing salinity tolerance in grass carp (Ctenopharyngodon idella): Insights from genome-wide association study and genomic selection.

Grass carp (Ctenopharyngodon idella) is one of the most widely cultured freshwater fish species globally. However, the expansion of its farming scale faces severe limitation owing to freshwater scarcity; therefore, the development of strains with greater salinity tolerance is key for expanding production using brackish water resources. To investigate the genetic basis of salinity tolerance in grass carp, a genome-wide association study (GWAS) was conducted using 200 individuals representing extreme phenotypes, namely salinity-tolerant and salinity-sensitive groups. In total, 17 single nucleotide polymorphisms (SNPs) related to salinity tolerance were detected, which were distributed across 11 chromosomes. Through gene annotation, 38 candidate genes were obtained from these loci. Enrichment analysis revealed these candidate genes are primarily implicated in key biological processes, including osmotic regulation, energy metabolism, and stress responses. Analyses of different SNP densities revealed that the 5 K SNP density panel can balance prediction accuracy and computational efficiency. The BayesA model achieved the highest prediction accuracy under the GWAS_Evenly selection strategy, with substantial reductions in mean absolute error and mean square error. This study reveals the genetic mechanisms of salinity tolerance in grass carp, which might be optimized through genomic selection, and provides insights for selectively breeding new varieties with greater salinity tolerance.

Animals

Sleep stage-dependent distribution of interictal epileptiform discharges in epilepsy: A systematic review.

BACKGROUND: Sleep and epilepsy interact through complex bidirectional mechanisms. Although NREM sleep facilitates interictal epileptiform discharges (IED), the diagnostic contribution of individual sleep stages remains uncertain. In particular, it is unclear whether deeper sleep stages such as N3 provide an advantage over N2 for spike detection or localization in clinical (electroencephalography) EEG practice. METHODS: This systematic review followed PRISMA 2020 guidelines. PubMed and Web of Science were searched for studies reporting quantitative IED measures across sleep stages in patients with epilepsy. Eligible studies included scalp EEG, video-EEG, polysomnography, or intracranial recordings. Mean IED rates per minute were derived when possible. Comparisons between NREM and REM sleep and between N2 and N3 stages were performed using study level non-parametric tests. Risk of bias was assessed with the ROBINS-I tool. RESULTS: Ten observational studies including 266 patients (mean age 30.1 years) were analyzed. IED rates were significantly higher during NREM than REM sleep (Wilcoxon signed-rank test, W = 0, p = 0.0019, r = 0.87). No significant difference was observed between N2 and N3 sleep, although median spike rates were slightly higher during N3 than N2 (0.99 vs 0.86 IED/min). REM showed the lowest activity. CONCLUSIONS: NREM sleep consistently exhibited higher IED rates than REM sleep, reinforcing the neurophysiological association between sleep stage and epileptiform activity without establishing diagnostic superiority.

Humans

BIOCARD framework: integrating fecal bile acids, lipids, and metabolites to assess response to a cardiovascular health intervention.

Cardiovascular disease (CVD) remains a leading cause of morbidity and mortality, particularly in under-resourced populations. Although nutritional interventions are important for CVD prevention, their outcomes are commonly evaluated using conventional clinical and behavioral indicators, which may not fully capture early molecular responses. In this study, we developed the BIOCARD framework, an exploratory fecal multi-omics platform integrating bile acids, lipids, and metabolites to evaluate intervention outcomes related to cardiovascular health. Fecal samples were collected from caregiver-child participants enrolled in a 10-week randomized controlled trial comparing a multicomponent garden-based intervention (SHA) with an education-only control group (MSP). Fecal polar metabolites, lipids, and bile acids were analyzed by UHPLC-HRMS-based approaches and integrated with conventional health indicators. Traditional clinical indicators in the present study showed limited sensitivity for detecting intervention-related differences. In contrast, fecal multi-omics analyzes revealed intervention-associated differences in metabolites, lipids, and bile acids, with children showing more apparent molecular variation than parents. Network analysis further revealed associations between selected molecular features and cardiovascular-related indicators, including blood pressure, body fat, skin carotenoids, and Healthy Eating Index scores. Together, these findings suggest that the BIOCARD framework may serve as an exploratory molecular approach to complement traditional outcome measures and improve the evaluation of nutritional interventions for cardiovascular health.

Humans

Clinical predictors of severe and fatal respiratory syncytial virus infection in adults and the elderly: A retrospective cohort study.

BACKGROUND: Respiratory syncytial virus (RSV) is increasingly recognized as a cause of severe respiratory illness in adults, especially the elderly and those with comorbidities. However, data on outcomes and risk factors for severe disease in this population remain limited. METHODS: We retrospectively analyzed 123 adult patients diagnosed with RSV infection at a tertiary center in Taiwan from 2015 to 2023. Clinical characteristics, laboratory data, detection of other pathogens, clinical course and outcome were reviewed. Multivariable logistic regression identified risk factors for severe RSV infection, including ICU admission and 30-day mortality. RESULTS: The mean age was 55.7 years; 50% were aged &#x2265;60 years and 13% were &#x2265;75 years. ICU admission occurred in 17%, with significant associations to viral coinfection and elevated C-reactive protein (CRP). Thirty-day mortality was 13%, and overall in-hospital mortality was 18%, all among patients with comorbidities. Independent predictors of 30-day mortality included late elderly (aOR 24.2, p&#x202f;=&#x202f;0.03), high CRP > 11.5&#x202f;mg/dL (aOR 16.4, p&#x202f;=&#x202f;0.005) and thrombocytopenia < 34,103/&#x3bc;L (aOR 11.4, p&#x202f;=&#x202f;0.01). CONCLUSION: Advanced age (&#x2265;75 years), high CRP, and severe thrombocytopenia are key predictors of mortality in adults RSV patients. These findings highlight the need for targeted prevention strategies, including vaccination, in high-risk populations.

Co-infection

Forensic taphonomy in fluvial water: A systematic review.

Human remains are frequently recovered from fluvial (lotic) water environments. Rivers, streams, canals and other flowing water bodies pose distinct challenges in forensic practice, particularly due to their current. Compared to other aquatic contexts, fluviatile taphonomy is underrepresented in the forensic literature and the last comprehensive summary was written over a decade ago. Therefore, a systematic review was performed to collect and summarise the current knowledge in forensics about fluvial taphonomy, including decomposition of remains, transport characteristics, search, postmortem submersion interval (PMSI) estimation, taphonomic alterations, and differences to other water bodies. 92 reports met the inclusion criteria for this review, most of them showed a moderate risk of bias. Their main findings were summarised and two major challenges identified. First, predictions about fluvial transport of human bodies pose a tremendous issue in forensic practice, leading to later detection and lower recovery rate of remains, complicating various subsequent analyses. Second, PMSI estimations are difficult particularly due to variable environmental conditions in fluviatile systems. Recommendations for future research in the area of fluvial forensic taphonomy include that case-related data such as the detailed decomposition state and river characteristics need to be made available. More standardised research protocols are required for a facilitated comparison between studies, environments and regions. This review provides forensic practitioners with a comprehensive, updated resource for the investigation of fluvial remains. It also guides future research towards a more efficient practice to build the basis for a broader, more robust and comprehensive synthesis, subsequently supporting analyses in forensic casework.

Humans

Integrative analysis of transcriptome and DNA methylome dynamics during caudal fin regeneration in silver pomfret (Pampus argenteus).

Caudal fin regeneration in teleost fish is a complex, multi-stage process involving coordinated molecular and cellular changes. While the role of epigenetic regulation particularly DNA methylation has been studied in model freshwater species such as zebrafish, its contribution to regeneration in marine teleosts remains largely unexplored. In this study, we integrated transcriptomic and DNA methylomic data to characterize the temporal dynamics of gene expression and methylation during caudal fin regeneration in the silver pomfret (Pampus argenteus). Using RNA-sequencing and reduced representation bisulfite sequencing (RRBS) at three biologically critical time points 1, 3, and 7&#xa0;days post-amputation (dpa), we characterized the spatiotemporal molecular landscape of caudal fin regeneration. These time points capture the key transitional phases of wound healing and inflammation (1 dpa), blastema formation and progenitor proliferation (3 dpa), and regenerative outgrowth with tissue remodeling (7 dpa), enabling robust detection of the major molecular programs underlying epimorphic regeneration. Concurrently, CG-methylome analysis identified thousands of dynamically changing differentially methylated regions (DMRs). A strong global inverse correlation was observed between promoter methylation and gene expression. Integrative analysis pinpointed key regeneration genes (fgf20a, msxb, sox9b) whose expression was associated with dynamic methylation changes in their promoters or gene bodies. We conclude that DNA methylation is a dynamic and key regulatory layer that acts in concert with transcriptional reprogramming to coordinate tissue regeneration, providing new insights into the epigenetic mechanisms underlying complex regenerative processes in teleosts.

Animals

Tracking GAD-specific T-cell expansions in Type 1 diabetes by intradermal GAD-Alum challenge.

Identifying and monitoring autoreactive T cells that drive beta cell destruction remains a major obstacle to developing effective immunotherapies for type 1 diabetes (T1D). These cells are extremely rare in peripheral blood and cannot be accessed directly from the pancreas. We used intradermal injection of Glutamic Acid Decarboxylase (GAD)-Alum to recruit GAD-specific T cells to accessible sites in the skin and skin-draining lymph nodes (LNs), sampled by skin suction blisters and ultrasound-guided LN aspiration. Peripheral blood samples obtained before GAD injection were restimulated with GAD in vitro to detect reactive CD4+ T cells. Single-cell RNA sequencing (scRNAseq) followed by re-expression of selected T cell receptors (TCRs) confirmed antigen specificity. Up to 70% of T cells at the skin injection site were clonally-expanded and 4 of 14 (28%) re-expressed TCRs were GAD-reactive. In LNs 1 of 14 (4%) clonally-expanded TCRs was GAD-reactive, representing ~0.08% of all T-cells. GAD-reactive cells across compartments displayed Th1 and Th17-associated transcription signatures. These results demonstrate the intradermal autoantigen challenge and scRNAseq, enable direct identification and molecular profiling of autoreactive T cells in vivo. This minimally invasive approach provides a powerful platform for tracking antigen-specific T cells to monitor disease activity and evaluate immune interventions in T1D.

Autoimmunity

Uncovering parental exposure risks of TCPP: Impaired development and metabolic homeostasis in zebrafish offspring.

As brominated flame retardants are phased out, tris (1&#x2011;chloro-2-propyl) phosphate (TCPP), a phosphorus-based flame retardant, has emerged as a prominent detectable flame retardant in the environment. However, TCPP has been found to exhibit endocrine-disrupting effects on organisms, raising significant safety concerns. In our study, we utilized the zebrafish model to explore the toxic effects of parental TCPP exposure on offspring and uncover its regulatory mechanisms through metabolomics analysis. Moreover, the impact on the nervous system and lipid metabolism was examined through behavioral analysis and specific staining. Our findings demonstrated that both embryonic and parental TCPP exposure induced developmental disorders in larvae, along with decreased locomotor activity and disordered lipid metabolism homeostasis. Parental exposure to TCPP, exhibiting stronger developmental toxicity than direct embryonic exposure, notably led to reductions in crucial energy substrates such as amino acids and carbohydrates. Meanwhile, embryonic TCPP exposure primarily affected the endogenous lipid-related metabolites including phospholipids, lipid-soluble vitamins, steroids and fatty acids, promoting lipid accumulation in larval liver and subcutaneous tissue. What's more, continuously parental and embryonic exposure showed the most pronounced effects on zebrafish development and metabolic regulation. Our study highlights the risk posed by parental exposure to TCPP on offspring zebrafish, underscoring the need for comprehensive consideration of the impact from parental exposure in pollutants regulation.

Animals

Genome-guided stage- and tissue-resolved transcriptome analysis of Serrodes campana identifies sex-biased antennal expression and candidate chemosensory-related genes.

Serrodes campana is an erebid moth of ecological and forestry relevance; its larvae are mainly associated with the soapberry tree, Sapindus mukorossi, whereas adults exhibit fruit-piercing behavior. However, stage- and tissue-resolved transcriptomic resources for this species remain limited. Here, using a chromosome-level reference genome, we performed a genome-guided transcriptome analysis of S. campana based on 12 RNA-seq libraries representing major developmental stages and key adult tissues. Global transcriptomic analyses revealed pronounced transcriptional differentiation across developmental stages and tissue types. Tissue-enriched gene sets and functional enrichment analyses identified distinct molecular signatures associated with developmental, sensory, and pheromone-associated tissues. Comparative analysis of female and male antennae further revealed sex-biased expression of several candidate chemosensory-related genes. Among 153 curated chemosensory-related candidate genes, most odorant receptor genes showed strong antennal enrichment, whereas other major chemosensory gene families displayed broader but still tissue-preferential expression patterns. In addition, an exploratory comparison of female terminal abdominal gland tissue and male terminal abdominal coremata revealed divergent expression profiles and highlighted candidate genes potentially associated with pheromone-related physiology, reproduction, and tissue-specific signaling. Together, this study provides the first genome-guided stage- and tissue-resolved transcriptomic resource for S. campana and offers a useful foundation for future studies of chemosensory detection, sex-biased gene expression, and pheromone-associated biology in this species.

Animals

CRISPR-Cas and Infectious Diseases: A Decade of Translational Advances in Molecular Biotechnology.

CRISPR-Cas systems have emerged as a versatile tool for diagnosing, treating, and preventing infectious diseases. This review highlights translational advancements in CRISPR-Cas-based applications, concentrating on the past decades in diagnostics, therapeutic genome editing, and vaccine development. The article highlights key platforms like DETECTR and SHERLOCK, which enable rapid, sensitive pathogen detection, and explores CRISPR-Cas9 systems in therapeutic strategies for directly targeting viral genomes and combating antimicrobial resistance. It also examines the role of CRISPR-Cas9 in engineering live-attenuated and personalized neoantigen vaccines. Principal findings demonstrate a clear progression from experimental proof-of-concept to preclinical applications primarily in CRISPR-based diagnostics and the engineering of live-attenuated vaccine candidates, whereas translation in CRISPR-based therapeutics and personalized neoantigen vaccines for infectious diseases remains at earlier, more exploratory stages. CRISPR-based diagnostics have progressed further toward clinical evaluation than therapeutics due to delivery and safety constraints, while personalized neoantigen vaccines are included mainly as an emerging, comparative concept for infectious diseases rather than a mature application. This review uniquely integrates CRISPR-based diagnostics, therapeutics, and vaccine development within a single infectious disease framework, critically assesses their current maturity, and systematically highlights technical, regulatory, and ethical barriers alongside realistic future priorities. The review concludes that while CRISPR-Cas holds transformative potential for infectious disease management, significant challenges in delivery efficiency, off-target effects, and ethical regulation must be addressed to ensure safe and equitable clinical translation.

Humans

Transcriptome analysis of the pectoral fin degeneration in half-smooth tongue sole (Cynoglossus semilaevis).

Appendage degeneration is a notable morphological feature of some teleosts with specialized benthic lifestyles. The half-smooth tongue sole (Cynoglossus semilaevis) undergoes severe pectoral fin regression during metamorphosis. However, the molecular basis underlying rapid pectoral fin degeneration remains unclear. Here, we performed time-series transcriptome sequencing on pectoral fins at pre-metamorphosis, metamorphosis peak and post-metamorphosis to characterize the molecular changes associated with pectoral fin degeneration. Transcriptional dynamics and functional enrichment showed that no significant enrichment of classical apoptosis-related transcriptional pathways was detected during pectoral fin degeneration. Instead, sustained downregulation of twist1b, identified as a transcriptomic candidate, together with significant upregulation of ssh1, coupled with enrichment of lysosome and ubiquitin-proteasome system (UPS) pathways, suggested enhanced tissue remodeling during pectoral fin degeneration. Temporal expression clustering revealed heterochronic misalignment in the developmental gene expression: upstream initiator tbx5 was upregulated at early metamorphosis, while downstream maintenance signal fgf10 decreased synchronously. Distal patterning gene hoxd12a exhibited premature expression and rapid decay, losing sustained late-phase expression. Moreover, transient elevation of gli3 during metamorphosis may contribute to restricted distal fin growth. We conclude that pectoral fin degeneration in C. semilaevis is associated with heterochronic disruption of developmental signaling and extensive tissue remodeling. This study provides transcriptomic insights into pectoral fin degeneration in tongue soles and establishes a basis for future functional studies of appendage reduction in teleosts.

Animals