SEARCH · PubMed Health

Results for “Bivalvia”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

13 recordsLinked to original sources

PubMed2026

The composition of the periostracum in the razor clam Sinonovacula constricta and the mantle's response to sulfide.

The razor clam Sinonovacula constricta inhabits sulfide-rich intertidal sediments and exhibits remarkable tolerance to this toxicant, yet the role of its periostracum in sulfide adaptation remains poorly understood. In this study, we investigated the composition and structure of the periostracum proteins, and the response of the mantle to sulfide stress. Scanning electron microscopy and energy-dispersive X-ray spectroscopy revealed that the periostracum is approximately 10 μm thick and contains 1.43 wt% sulfur, and proteomic analysis further confirmed the presence of organic sulfur (Cys/Met-rich proteins), suggesting its involvement in sulfur deposition. Using LC-MS/MS, we identified 77 high-confidence proteins from the periostracum, which were classified into six functional categories: enzymes, framework proteins, immune-related proteins, calcium ion-related proteins, other proteins, and proteins with unknown functions. Phylogenetic analyses of representative proteins revealed bivalve-specific evolutionary patterns, with several proteins exclusively present in Bivalvia, such as Unknown protein 2 and 7, which possess signal peptides and low-complexity domains. For the sulfide exposure experiment, razor clams were subjected to three Na2S concentrations (0, 10, and 100 μM). qPCR analysis showed that, compared with the control group, Chitin-binding protein 3 and Tyrosinase were significantly upregulated in the mantle, peaking in the 100 μM group at 48 h (5677.84-fold and 157.20-fold, respectively), whereas Collagen and Cadherin 3 were generally suppressed. This study represents one of the most comprehensive proteomic profiles of the razor clam periostracum and highlights the mantle's potential role in sulfide tolerance, offering insights for sulfur-tolerant aquaculture breeding and bioremediation applications.

Animals↗

PubMed2026

Characterization and functional insights of histone deacetylases in bivalves: implications for temperature and immune response in Chlamys nobilis.

Histone deacetylases serve as pivotal epigenetic regulators that modulate chromatin remodeling and gene transcription, playing critical roles in immune defense and environmental stress responses in aquatic organisms. However, the evolutionary characteristics and functional roles of the HDAC family in bivalves remain poorly understood. In this study, genome-wide identification of the HDAC family across 30 bivalve species yielded 558 HDAC genes. Phylogenetic reconstruction categorized these genes into four conserved groups and revealed a unique, bivalve-specific SIRT8 clade. Using the noble scallop Chlamys nobilis as a representative model, expression profiling revealed distinct expression patterns among CnHDAC members. Class I and most Class III members were predominantly expressed in the gonads, while Class II members were enriched in immune-related tissues, implying their potential involvement in bivalve immunity. Upon temperature stress, CnHDAC1/2, CnHDAC11-1, CnHDAC11-2, CnSIRT2-1, CnSIRT4, CnSIRT6, and CnSIRT8-3 were significantly induced, highlighting their critical roles in temperature adaptation. Upon Vibrio exposure, CnHDAC1/2, CnHDAC8, CnSIRT4, and CnSIRT6 were upregulated, while CnHDAC4/5/7/9, CnHDAC6/10, CnSIRT2-2, CnSIRT5, CnSIRT7, and CnSIRT8-3 were downregulated, suggesting a coordinated epigenetic regulatory mechanism underlying host immune defense. In conclusion, this study systematically elucidates the evolutionary landscape of the HDAC family and underscores its potential involvement in environmental resilience and host immunity, providing a theoretical basis for the breeding of disease-resistant and stress-tolerant aquaculture bivalves.

Animals↗

PubMed2026

Epitranscriptomic erasers in bivalves: Evolutionary divergence and species-specific transcriptional plasticity of the ALKBH family under acute thermal stress.

The AlkB homolog (ALKBH) family of Fe(II)/α-ketoglutarate-dependent dioxygenases mediates nucleic acid demethylation, thereby governing RNA metabolism and genomic stability. Despite their pivotal roles in epitranscriptomic regulation across vertebrates, the evolutionary dynamics and functional significance of ALKBH proteins in bivalve mollusks remain largely unexplored. Here, we present a comprehensive phylogenomic analysis of 210 ALKBH genes identified across 35 bivalve species. Our analyses reveal a distinct evolutionary trajectory characterized by the lineage-specific loss of ALKBH4 and the restricted distribution of ALKBH5 to the Mytilidae family, contrasting sharply with vertebrate repertoires. Using the noble scallop (Chlamys nobilis) and Pacific oyster (Crassostrea gigas) as model systems, we demonstrate that ALKBH genes exhibit conserved spatiotemporal expression patterns, with pronounced enrichment in gonadal tissues and during metamorphic transitions, implicating these enzymes in gametogenesis and larval development. Furthermore, comparative thermal stress experiments reveal divergent transcriptional plasticity: the subtropical scallop C. nobilis mounts rapid, transient induction of ALKBH1/2/6 under heat shock, whereas the eurythermal oyster C. gigas maintains sustained ALKBH3 expression, potentially underpinning its superior thermal tolerance. Conversely, cold stress elicits bimodal regulation in C. nobilis, with ALKBH1/2 upregulation contrasting with ALKBH6/7/8 suppression. These findings illuminate the functional diversification of bivalve ALKBH genes and their potential utility as molecular biomarkers for assessing developmental competence and thermal resilience in shellfish aquaculture.

Animals↗

PubMed2026

Comprehensive identification and evolutionary analysis of the Wnt gene family in bivalves: Insights into the larval development of the noble scallop Chlamys nobilis.

The Wnt gene family regulates fundamental developmental processes in metazoans, but its evolutionary composition and developmental deployment in bivalves remain largely unresolved. Here, we performed a comparative genomic analysis of Wnt genes in 19 bivalve species and examined developmental expression profiles in the noble scallop Chlamys nobilis, with Crassostrea gigas and Chlamys farreri used for cross-species comparison. A total of 235 Wnt genes were identified and assigned to 12 subfamilies. No reliable Wnt3 ortholog was detected in any analyzed bivalve, supporting the view that Wnt3 loss occurred early during lophotrochozoan evolution rather than representing a lineage-specific absence. Most Wnt proteins retained the conserved WNT domain, indicating strong structural conservation, whereas lineage-specific copy-number variation and gene loss were observed among species. C. farreri and C. gigas each retained 12 Wnt genes and lacked Wnt3, whereas C. nobilis lacked Wnt3, Wnt7, and Wnt16. Developmental transcriptome analysis and RT-qPCR revealed clear stage-specific expression patterns. In C. gigas, Wnt2/10/A were highly expressed during earlydevelopment and peaked around the D-shaped larval stage, while Wnt8 and Wnt11 showed distinct stage-specific peaks. By contrast, Wnt1/5/6/9 were more active during later larval development or juvenile formation. These results provide a comparative framework for bivalve Wnt evolution and identify candidate Wnt genes potentially involved in larval development and aquaculture-relevant developmental transitions.

Animals↗

PubMed2026

Evolutionary architecture and lineage-specific diversification of Forkhead box transcription factors in Perna viridis.

The Forkhead box (Fox) transcription factors are evolutionarily conserved regulators of development, cell cycle, and apoptosis across metazoans. This study provides the first comprehensive genome-wide analysis of the Fox gene family in the Asian green mussel (Perna viridis). We identified 28 Fox genes distributed across 10 chromosomes. Comparative analysis reveals the absence of the FoxI, FoxQ1, FoxR and FoxS subfamily, consistent with other bivalves and indicative of lineage-specific gene loss during molluscan evolution. Notably, gene duplications in the FoxAB, FoxD, FoxH, FoxN1-4, FoxQ2 and FoxQD subfamilies may reflect functional diversification associated with environmental adaptation. Exon-intron structural variability, including intron loss in several paralogues, suggests structural diversification and potential regulatory variation. Phylogenetic reconstruction confirmed the monophyly of core Fox classes while highlighting divergent expansion patterns in lophotrochozoans. Selection analyses showed strong purifying selection across duplicated Fox paralogs, supporting functional conservation after lineage-specific expansion. Gene Ontology enrichment linked Fox genes to stress response, apoptosis, and transcriptional regulation. By integrating phylogenetic, structural, and transcriptomic analyses, this study provides a genomic framework for understanding Fox gene organisation, evolution, and tissue-associated expression patterns in Perna viridis and establishes a comparative resource for future functional studies in bivalves.

Animals↗

PubMed2026

Evolutionary expansion of the NF-Y gene family in bivalves and divergent subunit responses to thermal and pathogenic stress in the noble scallop.

Nuclear factor Y (NF-Y) is a conserved eukaryotic transcription factor complex that specifically interacts with the CCAAT motif. Prior research has demonstrated that this gene family participates in various biological processes, encompassing growth, development, and stress responses, across a broad spectrum of organisms. However, research on the role of the NF-Y family in bivalves remains limited. In this study, we comprehensively identified the NF-Y family in 34 bivalve species, and further investigated its expression in the noble scallop Chlamys nobilis. A total of 296 NF-Y genes were identified and classified into three subfamilies, NF-YA, NF-YB, and NF-YC. Phylogenetic analysis revealed that NF-YA and NF-YC have remained relatively conserved, whereas NF-YB has undergone significant expansion. Additionally, while substantial disparities in gene copy numbers exist across species, the motif composition and exon-intron structures within each subfamily demonstrate notable conservation. Tissue expression profiling revealed distinct expression patterns among CnNF-Y genes, with several members exhibiting relatively high transcript abundance in gonadal tissues. Furthermore, qRT-PCR results demonstrated that CnNF-YA2, CnNF-YB6, and CnNF-YC were significantly and continuously upregulated under heat stress. Conversely, several genes, particularly CnNF-YA2, CnNF-YB3, and CnNF-YB4, exhibited dynamic transcriptional responses to Vibrio parahaemolyticus exposure. These findings enhance our understanding of the evolutionary trajectory and functional diversification of the NF-Y gene family in bivalves, laying a theoretical foundation for future research on thermal adaptation, immune regulation, and molecular breeding in scallops.

Animals↗

PubMed2026

Genome-wide identification and expression analysis of the CREB/ATF family and its potential role in melanogenesis in the Manila clam (Ruditapes philippinarum).

Ruditapes philippinarum is an economically important bivalve species in China, and shell color is a trait of ecological and commercial significance. Melanin is a key determinant of shell color, and members of the CREB/ATF family have been reported to participate in melanogenesis in other organisms. In this study, members of the CREB/ATF family were systematically identified at the whole-genome level based on genomic and transcriptomic datasets, followed by analyses of their phylogenetic relationships, gene structures, and expression patterns. A total of six CREB/ATF family members were identified and classified into five subfamilies. Expression profiling and RT-qPCR validation revealed that most CREB/ATF genes were highly expressed in the mantle and displayed clear differences among shell-color phenotypes. Except for RpATF4 and RpCREBZF, most members exhibited relatively high expression levels in dark-colored shell strains, particularly in black and zebra-striped clams. Moreover, most genes showed low expression during early embryonic and larval stages but increased expression at the single-siphon spat and juvenile stages. These results suggest that the CREB/ATF family may be involved in melanin-associated shell-color regulation in R. philippinarum, providing important candidate genes and a theoretical basis for further elucidating the molecular mechanisms of shell-color formation in mollusks.

Animals↗

PubMed2026

Transcriptomic insights into the coordinated regulation of signaling, apoptosis, immunity, and metabolism during Sinonovacula constricta larval metamorphosis.

Metamorphosis is a critical ontogenetic transition for marine bivalves, marking the shift from planktonic to benthic lifestyles, where successful transformation dictates survival. The razor clam Sinonovacula constricta is economically important; however, low larval metamorphosis rates remain a major bottleneck in seedling production. To elucidate the mechanisms governing this process, we performed a comparative transcriptome analysis of S. constricta larvae at pre- and post-metamorphosis stages using Illumina sequencing. A total of 3701 differentially expressed genes (DEGs) were identified, including 3254 up-regulated and 447 down-regulated genes. Functional annotation of the respective top 20 significantly up-regulated and down-regulated DEGs indicated their potential pivotal roles in signal transduction (e.g., up-regulated: CAV1, CHRNA2; down-regulated: APP, NOTCH1), cellular proliferation and differentiation (e.g., up-regulated: TUBA, EGF1; down-regulated: KIF23, TTC25), transcriptional and epigenetic regulation (e.g., up-regulated: NFIL3; down-regulated: OVO, HMX1), substance transport (e.g., up-regulated: LRP2, LRP1B; down-regulated: SLC51A, Slc33a1), substance metabolism (e.g., up-regulated: CPK3, CYP26A1; down-regulated: RDMT1, ADAC), immunomodulation (e.g., up-regulated: CPN2, CRISP2), and protein homeostasis (e.g., up-regulated: HSP27, NAS-27). Functional enrichment analysis further revealed that DEGs were significantly enriched in pathways related to signal transduction and developmental regulation (e.g., Ras, TNF), cell death and homeostasis (e.g., apoptosis), immune responses (e.g., Toll-like receptor), energy metabolism (e.g., lipid), cardiovascular related (e.g., Fluid shear stress), cell junction and architecture (e.g., Tight junction), and infectious disease (e.g., measles). These results suggest a synergistic interplay between signaling, apoptosis, immunity, and metabolism during S. constricta metamorphosis. This study advances our understanding of marine bivalve metamorphosis and offers candidate genes for further mechanistic studies.

Animals↗

PubMed2025

High-quality chromosome-level genome of three Meretrix species using Nanopore and Hi-C technologies.

Meretrix is a commercially valuable bivalve genus in Asia, but only one reference genome has hindered comprehensive genetic studies and germplasm resource evaluation. In this study, we present three reference genomes of Meretrix species: Meretrix sp. MF1, Meretrix sp. MT1, and Meretrix lamarckii JML1. Meretrix sp. MF1 was assembled at the chromosome level using Nanopore sequencing and Hi-C technologies, whereas Meretrix sp. MT1 and Meretrix lamarckii were assembled as scaffold-level assemblies. The chromosome-level genome of Meretrix sp. MF1 consists of 36 contigs, including 19 chromosomes and 17 scaffolds, with a total length of 883.3 Mb and a scaffold N50 of 46.87 Mb. Notably, the genome of Meretrix sp. MF1, a putative novel species, exhibits an Average Nucleotide Identity (ANI) of 94.33% with its closest relative, Meretrix lamarckii. These genomic resources not only provide a crucial foundation for genetic research on Meretrix but also contribute to the development of effective conservation strategies for its sustainable management.

Animals↗

PubMed2025

Chromosome-level genome assembly of bivalve mollusk, Xishishe Coelomactra antiquata.

Coelomactra antiquata, a significant marine economic shellfish in China, is experiencing a natural population decline due to habitat destruction and overfishing, making the restoration and conservation of its natural resources an urgent priority. This study provides a high - quality chromosome - level genome assembly for C. antiquata, created by PacBio and Hi - C sequencing and resulting in a 19 - chromosome map. The assembly encompasses a genome size of 807.31 Mb, with a contig N50 of 17.35 Mb and a scaffold N50 of 42.90 Mb. A total of 28,070 protein - coding genes were identified, 25,959 of which were functionally annotated. Overall, this study offers a chromosome - level genome for C. antiquata that is highly continuous and complete, providing an indispensable resource for subsequent molecular and genetic studies of this species.

Animals↗

PubMed2026

Target Capture of Ancient Shell DNA Enables Phylogenetic Reconstruction of Deep-Sea Molluscs.

Target capture is widely used to enrich endogenous DNA from calcium phosphate skeletal material in vertebrates, but its performance on calcium carbonate hard parts widely produced by invertebrates remains poorly understood. Here, we compared DNA recovery from four fresh and 12 ancient (eight radiocarbon-dated to 1671-1135 years old before present) deep-sea vesicomyid clam shells, including species Archivesica marissinica, A. nanshaensis and A. okutanii, using whole-genome sequencing (WGS) or target capture of ultraconserved elements (UCEs). WGS achieved 16.65% on-target read recovery of UCEs from fresh soft tissue, but < 1% from shell specimens. By contrast, UCE capture in the same specimen increased on-target reads by up to 155-fold, reaching 29.84% in fresh shells and up to 72-fold, reaching 19.89% in ancient shells. Target capture of UCEs recovered 142-1001 loci per sample compared to 0-230 with WGS alone. Ancient shells of A. marissinica and A. okutanii, based on reads mapped with bwa-mem2 and bbmap, exhibited characteristic post-mortem DNA damage signals, with average 5'-end C-to-T misincorporation rates of 3.46% and 15.97%, respectively, exceeding the levels observed in fresh A. marissinica shells (maximum 1.24%). UCE-based phylogenetic reconstructions incorporating shell ancient DNA recovered two major clades within Pliocardiinae, consistent with published phylogenomic trees. Together, these findings demonstrate that target-capture enrichment enables effective recovery of highly degraded DNA from ancient mollusc shells and supports robust phylogenetic inference at the intrageneric scale, expanding the utility of shells-one of the most abundant invertebrate remains-for evolutionary, biogeographic and conservation studies.

Animals↗

PubMed2025

Comparative Genomics of Sex-Determination-Related Genes Reveals Shared Evolutionary Patterns Between Bivalves and Mammals, but Not Fruit Flies.

The molecular basis of sex determination (SD), while being extensively studied in model organisms, remains poorly understood in many animal groups. Bivalves, a diverse class of molluscs with a variety of reproductive modes, represent an ideal yet challenging clade for investigating SD and the evolution of sexual systems. However, the absence of a comprehensive framework has limited progress in this field, particularly regarding the study of sex-determination-related genes (SRGs). In this study, we performed a genome-wide sequence evolutionary analysis of the Dmrt, Sox and Fox gene families in more than 40 bivalve species. For the first time, we provide an extensive and phylogenetically aware dataset of these SRGs, and we find support for the hypothesis that Dmrt-1L and Sox-H may act as primary sex-determining genes by showing their high levels of sequence diversity within the bivalve genomic context. To validate our findings, we studied the same gene families in two well-characterised systems, mammals and fruit flies (genus Drosophila). In the former, we found that the male sex-determining gene Sry exhibits a pattern of amino acid sequence diversity similar to that of Dmrt-1L and Sox-H in bivalves, consistent with its role as master SD regulator. In contrast, no such pattern was observed among genes of the fruit fly SD cascade, which is controlled by a chromosomic mechanism. Overall, our findings highlight similarities in the sequence evolution of some mammal and bivalve SRGs, possibly driven by a comparable architecture of SD cascades. This work underscores once again the importance of employing a comparative approach when investigating understudied and non-model systems.

Animals↗

PubMed2024

Oceanic islands act as drivers for the genetic diversity of marine species: Cardita calyculata (Linnaeus, 1758) in the NE Atlantic as a case-study.

Geographic distribution, as well as evolutionary and biogeographic processes and patterns of marine invertebrate benthic species are strongly shaped by dispersal ability during the life cycle. Remote oceanic islands lie at the brink of complex biotic and abiotic interactions which have significantly influenced the biodiversity patterns we see today. The interaction between geological environmental change and taxon-specific dispersal modes can influence species evolutionary patterns, eventually delimiting species-specific biogeographic regions. In this study, we compare the population genetic patterns of the marine bivalve Cardita calyculata in the northeast Atlantic, discussing the role of Macaronesian islands during past climatic cycles. The genetic structure and diversity patterns were outlined based on SSR-GBAS loci of 165 individuals and on the mitochondrial COI marker of 22 individuals from the Canary Islands, Madeira, Azores and the Mediterranean. The highly structured genetic pattern found among regions and within archipelagos suggests the central role of oceanic islands in promoting the divergence of the species in both the NE Atlantic and the Mediterranean. The high degree of divergence in the COI dataset (> 7%) suggests the existence of potential cryptic speciation that needs to be further explored with a more comprehensive sampling. Such patterns are only congruent with a scenario where C. calyculata populations were maintained during glacial/interglacial cycles, supporting the role of the studied archipelagos as drivers of diversity for marine biota. We stress the importance of developing studies for species with various life history and dispersal modes. In such a way, a more profound understanding of the biogeographic and evolutionary significance of oceanic islands can catalyse directed conservation efforts, especially in the context of the ongoing climate crisis.

Animals↗