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Phototransduction is based on opsins that drive distinct types of Gα cascades. Although nonvisual photosensitivity has long been known in marine bivalves, the underlying molecular basis and phototransduction mechanism are poorly understood. Here, we introduced the eyeless razor clam Sinonovacula constricta as a model to clarify this issue. First, we showed that S. constricta was highly diverse in opsin family members, with a significant expansion in xenopsins. Second, the expression of putative S. constricta opsins was highly temporal-spatio specific, indicating their potential roles in S. constricta development and its peripheral photosensitivity. Third, by cloning four S. constricta opsins with relatively higher expression (Sc_opsin1, 5, 7, and 12), we found that they exhibited different expression levels in response to different light environments. Moreover, we demonstrated that these opsins (excluding Sc_opsin7) couple with Gαq and Gαi cascades to mediate the light-dependent Ca2+ (Sc_opsin1 and 5) and cAMP (Sc_opsin12) signaling pathways. The results indicated that Sc_opsin1 and 5 belonged to Gq-opsins, Sc_opsin12 belonged to Gi-opsins, while Sc_opsin7 might act as a photo-isomerase. Furthermore, we found that the phototransduction function of S. constricta Gq-opsins was dependent on the lysine at the seventh transmembrane domain, and greatly influenced by the external light spectra in a complementary way. Thus, a synergistic photosensitive system mediated by opsins might exist in S. constricta to rapidly respond to the transient or subtle changes of the external light environment. Collectively, our findings provide valuable insights into the evolution of opsins in marine bivalves and their potential functions in nonvisual photosensitivity.
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Bivalves , Transdução de Sinal Luminoso , Opsinas , Animais , Bivalves/genética , Bivalves/fisiologia , Opsinas/genética , Opsinas/fisiologia , FilogeniaRESUMO
Reconstructing the tree of life and understanding the relationships of taxa are core questions in evolutionary and systematic biology. The main advances in this field in the last decades were derived from molecular phylogenetics; however, for most species, molecular data are not available. Here, we explore the applicability of two deep learning methods - supervised classification approaches and unsupervised similarity learning - to infer organism relationships from specimen images. As a basis, we assembled an image dataset covering 4144 bivalve species belonging to 74 families across all orders and subclasses of the extant Bivalvia, with molecular phylogenetic data being available for all families and a complete taxonomic hierarchy for all species. The suitability of this dataset for deep learning experiments was evidenced by an ablation study resulting in almost 80% accuracy for identifications on the species level. Three sets of experiments were performed using our dataset. First, we included taxonomic hierarchy and genetic distances in a supervised learning approach to obtain predictions on several taxonomic levels simultaneously. Here, we stimulated the model to consider features shared between closely related taxa to be more critical for their classification than features shared with distantly related taxa, imprinting phylogenetic and taxonomic affinities into the architecture and training procedure. Second, we used transfer learning and similarity learning approaches for zero-shot experiments to identify the higher-level taxonomic affinities of test species that the models had not been trained on. The models assigned the unknown species to their respective genera with approximately 48% and 67% accuracy. Lastly, we used unsupervised similarity learning to infer the relatedness of the images without prior knowledge of their taxonomic or phylogenetic affinities. The results clearly showed similarities between visual appearance and genetic relationships at the higher taxonomic levels. The correlation was 0.6 for the most species-rich subclass (Imparidentia), ranging from 0.5 to 0.7 for the orders with the most images. Overall, the correlation between visual similarity and genetic distances at the family level was 0.78. However, fine-grained reconstructions based on these observed correlations, such as sister-taxa relationships, require further work. Overall, our results broaden the applicability of automated taxon identification systems and provide a new avenue for estimating phylogenetic relationships from specimen images.
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BACKGROUND: In bivalves, the rate at which organisms grow is a major functional trait underlying many aspects of their commercial production. Growth is a highly polygenic trait, which is typically regulated by many genes with small to moderate effects. Due to its complexity, growth variability in such shellfish remains poorly understood. In this study, we aimed to investigate differential gene expression among spat of the pearl oyster Pinctada margaritifera with distinct growth phenotypes. RESULTS: We selected two groups of P. margaritifera spat belonging to the same F2 cohort based on their growth performance at 5.5 months old. Transcriptome profile analysis identified a total of 394 differentially expressed genes between these Fast-growing (F) and Slow-growing (S) phenotypes. According to functional enrichment analysis, S oysters overexpressed genes associated with stress-pathways and regulation of innate immune responses. In contrast, F oysters up-regulated genes associated with cytoskeleton activity, cell proliferation, and apoptosis. Analysis of genome polymorphism identified 16 single nucleotide polymorphisms (SNPs) significantly associated with the growth phenotypes. SNP effect categorization revealed one SNP identified for high effect and annotated for a stop codon gained mutation. Interestingly, this SNP is located within a gene annotated for scavenger receptor class F member 1 (SRF1), which is known to modulate apoptosis. Our analyses also revealed that all F oysters showed up-regulation for this gene and were homozygous for the stop-codon mutation. Conversely, S oysters had a heterozygous genotype and a reduced expression of this gene. CONCLUSIONS: Altogether, our findings suggest that differences in growth among the same oyster cohort may be explained by contrasted metabolic allocation between regulatory pathways for growth and the immune system. This study provides a valuable contribution towards our understanding of the molecular components associated with growth performance in the pearl oyster P. margaritifera and bivalves in general.
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Perfilação da Expressão Gênica , Pinctada , Polimorfismo de Nucleotídeo Único , Animais , Pinctada/genética , Pinctada/crescimento & desenvolvimento , Transcriptoma , FenótipoRESUMO
The phylum Ciliophora (ciliates) comprises about 2600 symbiotic and over 5500 free-living species. The inclusion of symbiotic ciliates in phylogenetic analyses often challenges traditional classification frameworks due to their morphological adaptions to the symbiotic lifestyle. Conchophthirus is such a controversial obligate endocommensal genus whose affinities to other symbiotic and free-living scuticociliates are still poorly understood. Using uni- and multivariate morphometrics as well as 2D-based molecular and phylogenetic analyses, we attempted to test for the monophyly of Conchophthirus, study the boundaries of Conchophthirus species isolated from various bivalves at mesoscale, and reveal the phylogenetic relationships of Conchophthirus to other scuticociliates. Multidimensional analyses of morphometric and cell geometric data generated the same homogenous clusters, as did phylogenetic analyses based on 144 new sequences of two mitochondrial and five nuclear molecular markers. Conchophthirus is not closely related to 'core' scuticociliates represented by the orders Pleuronematida and Philasterida, as assumed in the past using morphological data. Nuclear and mitochondrial markers consistently showed the free-living Dexiotricha and the mouthless endosymbiotic Haptophrya to be the nearest relatives of Conchophthirus. These three highly morphologically and ecologically dissimilar genera represent an orphan clade from the early radiation of scuticociliates in molecular phylogenies.
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Cilióforos , Oligoimenóforos , Filogenia , Análise de Sequência de DNA , Cilióforos/genética , MitocôndriasRESUMO
Bivalves are nutritious animal protein source for humans, rich in high quality proteins, lipids, and carbohydrates. Many studies have shown that ocean warming has detrimental effects on the nutritional quality of bivalves. Although a number of studies are available on the effect of ocean warming on the nutritional value of bivalves, this information is not well organized. In this context, the current study provides a critical review of the effects of ocean warming on the nutritional quality of commercially important edible marine bivalves. In general, ocean warming has caused a reduction in the total lipid and carbohydrate content of bivalves, especially those bivalves inhabiting temperate regions. As for protein, there is no general trend in the effects of ocean warming on the protein reserves of bivalves. In addition, the specific effects of elevated temperature on the macro-nutrients of bivalves highly depend on the tissues, sex and developmental stages of bivalves, as well as seasonal factors. This review not only fills in the knowledge gap regarding the effects of elevated temperature on the macro-nutrients of commercially important marine bivalves but also provides guidance for the establishment of bivalve aquaculture and fisheries management plans to mitigate the impact of climate change.
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Bivalves are a high-quality source of animal protein for human consumption. In recent years, the demand for bivalve proteins has increased dramatically, leading to a sharp increase in global production of marine bivalves. To date, although the amino acid profiles of many bivalves have been reported, such information has not been well organized. Therefore, there is an urgent need for a comprehensive scientific review of the protein quality of bivalves, especially commercially important edible bivalves. In this context, this study was conducted to evaluate the protein quality of commercially important edible bivalves. In general, most bivalves are rich in protein (> 50% of their dry weight) and amino acids (> 30 g/100g protein). Although most species of bivalves are rich in essential amino acids (EAA) (up to 50 g/100g protein), some species of edible bivalves have very low levels of EAA (< 5 g/100g protein). Based on the AA score, almost all bivalves have at least two limiting AAs. Most bivalve proteins provides delicious flavors with unami, sweetness and a hint of bitterness. The findings of this study not only serve as a a guide for selecting appropriate bivalves based on consumer preferences for specific AAs or AA scores, but also provide information on potential bivalve species for aquaculture to produce higher protein quality to meet the growing demand for high quality animal protein.
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Nitric oxide (NO) is a signaling molecule and immune effector produced by the nitric oxide synthases (NOS), which involved to various physiological processes of animals. In marine bivalves, hemocytes play important roles in antimicrobial innate immune response. Although hemocyte-derived NO has been detected in several bivalves, the immune function of hemocyte-derived NO is not well understood. Here, we investigated the antibacterial response of hemocyte-derived NO in the blood clam Tegillarca granosa. Two types of hemocytes including erythrocytes and granulocytes were isolated by Percoll density gradient centrifugation, their NO production and TgNOS expression level were analyzed. The results showed that NO was mainly produced in granulocytes and almost no detected in erythrocytes. The granulocytes showed significantly higher NO level and TgNOS expression level than the erythrocytes. And the TgNOS expression level was significantly increased in granulocytes after Vibro parahemolyticus challenge. In addition, the NO donor sodium nitroprusside (SNP) significantly increased the NO production of hemocytes to kill pathogenic bacteria. In summary, the results revealed that granulocytes-derived NO play vital roles in the antimicrobial immune response of the blood clam.
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Anti-Infecciosos , Arcidae , Bivalves , Animais , Óxido Nítrico , Imunidade Inata , Antibacterianos , Granulócitos , HemócitosRESUMO
Benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE) is the active intermediate metabolite of benzo[a]pyrene (B[a]P) and is considered the ultimate immunotoxicant. The neuroendocrine immunoregulatory network of bivalves is affected under pollutant stress. Besides, bivalves are frequently affected by pollutants in marine environments, yet the combined effects of neuroendocrine factors and detoxification metabolites on bivalves under pollutant stress and the signal pathways that mediate this immunoregulation are not well understood. Therefore, we incubated the hemocytes of Chlamys farreri with the neuroendocrine factor noradrenaline (NA) and the B[a]P detoxification metabolite BPDE, alone or in combination, to examine the immunotoxic effects of NA and BPDE on the hemocytes in C. farreri. Furthermore, the effects of NA and BPDE on the hemocyte signal transduction pathway were investigated by assessing potential downstream targets. The results revealed that NA and BPDE, alone or in combination, resulted in a significant decrease in phagocytic activity, bacteriolytic activity and the total hemocyte count. In addition, the immunotoxicity induced by BPDE was further exacerbated by co-treatment with NA, and the two showed synergistic effects. Analysis of signaling pathway factors showed that NA activated G proteins by binding to α-AR, which transmitted information to the Ca2+-NF-κB signaling pathway to regulate the expression of phagocytosis-associated proteins and regulated cytokinesis through the cAMP signaling pathway. BPDE could activate PTK and affect phagocytosis and cytotoxicity proteins through Ca2+-NF-κB signal pathway, also affect the regulation of phagocytosis and cytotoxicity by inhibiting the AC-cAMP-PKA pathway to down-regulate the expression of NF-κB and CREB. In addition, BPDE and NA may affect the immunity of hemocytes by down-regulating phagocytosis-related proteins through inhibition of the lectin pathway, while regulating the expression of cytotoxicity-related proteins through the C-type lectin. In summary, immune parameters were suppressed through Ca2+ and cAMP dependent pathways exposed to BPDE and the immunosuppressive effects were enhanced by the neuroendocrine factor NA.
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Poluentes Ambientais , Pectinidae , Animais , Benzo(a)pireno , 7,8-Di-Hidro-7,8-Di-Hidroxibenzo(a)pireno 9,10-óxido/metabolismo , 7,8-Di-Hidro-7,8-Di-Hidroxibenzo(a)pireno 9,10-óxido/farmacologia , Hemócitos/metabolismo , NF-kappa B , Norepinefrina , Pectinidae/metabolismoRESUMO
Microplastics (MPs) are ubiquitous pollutant causing severe threat to the biotic and abiotic components of the coastal ecosystem. Accumulation of MPs in the commercially important bivalves Viz. Perna viridis (green mussel) and Meretrix casta (clam) collected from four different locations of Beypore estuary, Southern India was studied. The study focused on the accumulation, characteristics, diversity indices, and human health risk assessment of MPs in the bivalves of Beypore estuary. A total of 120 bivalve samples were examined for the MPs contamination. Whole tissue digestion method using 10% KOH was employed to retrieve the MP content. The results indicate that the average abundance of MPs in Perna viridis is 2.38 ± 1.56 MPs/individual and 0.15 ± 0.09 MP/g/wet weight whereas, for Meretrix casta it is 1.35 ± 1.02 MPs/individual and 0.3 ± 0.27 MP/g/wet weight. Spearman's correlation reveals that there is no significant correlation observed between the abundance of MPs in the bivalves with their morphomertric parameters. The characteristics of MPs in the bivalves are dominated by translucent colored particles (88.95%) in the form of films (45.13%) and fibers (33.6%) having a size ranged between 300 and 1000 µm (51.13%) and composed of polyethylene (54.5%) and polypropylene (20%) polymers. The microplastic index in Meretrix casta ranged between 0.02 and 0.07 whereas for Perna viridis it ranged between 0.08 and 0.10 indicating minimal to moderate MPs contamination. The microplastics diversity integrated index ranged between 0.67 and 0.69 for Meretrix casta whereas, for Perna viridis the value ranged between 0.34 and 0.60 suggests moderate diversity of MPs derived from multiple sources. Based on polymer hazard index, the potential health risk was assessed with a hazard level ranged between II and IV suggesting significant health risk. Systematic monitoring of MPs at river basin scale along with stringent plastic waste management is required to minimize plastic pollution load into the river system.
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Animal and plant species exhibit an astonishing diversity of sexual systems, including environmental and genetic determinants of sex, with the latter including genetic material in the mitochondrial genome. In several hermaphroditic plants for example, sex is determined by an interaction between mitochondrial cytoplasmic male sterility (CMS) genes and nuclear restorer genes. Specifically, CMS involves aberrant mitochondrial genes that prevent pollen development and specific nuclear genes that restore it, leading to a mixture of female (male-sterile) and hermaphroditic individuals in the population (gynodioecy). Such a mitochondrial-nuclear sex determination system is thought to be rare outside plants. Here, we present one possible case of CMS in animals. We hypothesize that the only exception to the strict maternal mtDNA inheritance in animals, the doubly uniparental inheritance (DUI) system in bivalves, might have originated as a mitochondrial-nuclear sex-determination system. We document and explore similarities that exist between DUI and CMS, and we propose various ways to test our hypothesis.
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DNA Mitocondrial , Genoma Mitocondrial , Animais , DNA Mitocondrial/genética , Feminino , Genes Mitocondriais/genética , Genoma Mitocondrial/genética , Padrões de Herança/genética , Infertilidade das PlantasRESUMO
Due to increasing anthropogenic perturbation and water eutrophication, cyanobacterial blooms (CYBs) have become a global ecological and environmental problem. Toxic CYBs and elevated pH are considered to be the two key stressors associated with eutrophication in natural waters, particularly in the event of CO2 depletion induced by dense blooms. However, previous research has been focused on investigating the impacts of toxic CYBs or pH changes in isolation, whereas the interactive effects of such stressors on edible bivalves that inhabit CYB waters still lack information. In this study, the combined effects of toxic Microcystis aeruginosa and pH shifts on the antioxidant responses, immune responses, and apoptosis of the edible freshwater bivalve Corbicula fluminea were explored. The results showed that the activity of antioxidant enzymes was significantly impacted by the interactive effects between toxic M. aeruginosa exposure and time course, yet pH shifts showed no significant effects on the activities of these antioxidant enzymes, implying that the antioxidant response in C. fluminea was mainly triggered by toxic M. aeruginosa exposure. Toxic M. aeruginosa also induced an increased production of reactive oxygen species and malondialdehyde in treated clams, particularly under high pH settings. The elevated lysosomal enzyme activity helped C. fluminea defend against toxic M. aeruginosa exposure under high pH conditions. The principal component analysis (PCA) and the integrated biomarker response (IBR) results suggested that the treated clams were subjected to the elevated toxicity of toxic M. aeruginosa in conditions of high pH. The heat shock proteins-related genes might be triggered to resist the oxidative damage in treated clams. Moreover, the upregulation of TNF and casp8 genes indicated the potential activation of the caspase8-mediated apoptotic pathway through TNF receptor interaction, potentially resulting in apoptosis. The TUNEL assay results further confirmed that apoptosis appeared in treated clams. These findings improve our understanding of the combined toxicological effects of harmful algae and pH shifts on bivalves, which will provide insights into a comprehensive ecological risk assessment of toxic CYBs to edible bivalve species.
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Antioxidantes , Apoptose , Corbicula , Microcystis , Animais , Concentração de Íons de Hidrogênio , Corbicula/efeitos dos fármacos , Apoptose/efeitos dos fármacos , Antioxidantes/metabolismo , Água Doce , Espécies Reativas de Oxigênio/metabolismo , Eutrofização , Estresse Oxidativo/efeitos dos fármacos , Malondialdeído/metabolismoRESUMO
Sessile intertidal organisms live in a harsh environment with challenging environmental conditions and increasing anthropogenic pressure such as microplastic (MP) pollution. This study focused on effects of environmentally relevant MP concentrations on the metabolism of intertidal Pacific oyster Crassostrea gigas, and its potential MP-induced vulnerability to warming during midday low tide. Oysters experienced a simulated semidiurnal tidal cycle based on their natural habitat, and were exposed to a mixture of polystyrene microbeads (4, 7.5 and 10⯵m) at two environmentally relevant concentrations (0.025⯵gâ¯L-1 and 25⯵gâ¯L-1) for 16 days, with tissue samplings after 3 and 12 days to address dose-dependent effects over time. On the last day of exposure, the remaining oysters were additionally exposed to low tide warming (3 °C h-1) to investigate possible MP-induced susceptibility to aerial warming. Metabolites of digestive gland and gill tissues were analysed by using untargeted 1H nuclear magnetic resonance (NMR) based metabolomics. For the digestive gland metabolite profiles were comparable to each other independent of MP concentration, exposure time, or warming. In contrast, gill metabolites were significantly affected by high MP exposure and warming irrespective of MP, initiating the same cellular stress response to counteract induced oxidative stress. The activated cascade of antioxidant defence mechanisms required energy on top of the general energy turnover to keep up homeostasis, which in turn may lead to subtle, and likely sub-lethal, effects within intertidal oyster populations. Present results underline the importance of examining the effects of environmentally relevant MP concentrations not only alone but in combination with other environmental stressors.
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The pregnane X receptor (PXR) is a nuclear hormone receptor that plays a pivotal role in regulating gene expression in response to various ligands, particularly xenobiotics. In this context, the aim of this study was to shed light on the ligand affinity and functions of four NR1J1 paralogs identified in the marine mussel Mytilus galloprovincialis, employing a dual-luciferase reporter assay. To achieve this, the activation patterns of these paralogs in response to various toxins, including freshwater cyanotoxins (Anatoxin-a, Cylindrospermopsin, and Microcystin-LR, -RR, and -YR) and marine algal toxins (Nodularin, Saxitoxin, and Tetrodotoxin), alongside natural compounds (Saint John's Wort, Ursolic Acid, and 8-Methoxypsoralene) and microalgal extracts (Tetraselmis, Isochrysis, LEGE 95046, and LEGE 91351 extracts), were studied. The investigation revealed nuanced differences in paralog response patterns, highlighting the remarkable sensitivity of MgaNR1J1γ and MgaNR1J1δ paralogs to several toxins. In conclusion, this study sheds light on the intricate mechanisms of xenobiotic metabolism and detoxification, particularly focusing on the role of marine mussel NR1J1 in responding to a diverse array of compounds. Furthermore, comparative analysis with human PXR revealed potential species-specific adaptations in detoxification mechanisms, suggesting evolutionary implications. These findings deepen our understanding of PXR-mediated metabolism mechanisms, offering insights into environmental monitoring and evolutionary biology research.
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Toxinas Marinhas , Mytilus , Receptor de Pregnano X , Animais , Receptor de Pregnano X/metabolismo , Receptor de Pregnano X/genética , Mytilus/metabolismo , Mytilus/genética , Humanos , Microcistinas/metabolismo , Microalgas/metabolismo , Microalgas/genética , Xenobióticos/metabolismo , Toxinas Bacterianas/metabolismo , Toxinas de CianobactériasRESUMO
The mobile genetic elements IS630/Tc 1/mariner (ITm) are widespread DNA transposons that make a significant contribution to the evolution of eukaryotic genomes. With the start of large-scale application of next-generation sequencing (NGS) technologies and the emergence of many new whole genome sequences of organisms in nucleotide sequence collections, the ITm elements have been identified in most taxa of the eukaryotic tree of life. Although ITm diversity has been studied in detail, new elements are still found, thus expanding the respective DNA transposon group and calling for review of its classification. Bivalve L31 elements were for the first time analyzed in detail to describe their structures, diversity, distribution, and phylogenetic position among the ITm elements. The L31 transposons were found to form an independent superfamily of an ancient origin within the ITm group. Rather high diversity was observed within the L31 clade; i.e., five phylogenetic clusters were identified. In mollusks, the L31 transposons have been detected only in the subclass Autobranchia and predominate in diversity and number in the infraclass Pteriomorphia. A protein encoded by open reading frame 2 (ORF2) was shown to be an integral structural component of almost all full-length L31 elements. The results provide for a better understanding of the evolution of particular ITm transposons. Further study of the L31 transposons in other taxa (cnidarians) and functional investigation of the ORF2 protein product will help to better understand the evolution of DNa transposons, the mechanisms of their horizontal transfer, and their contribution to eukaryotic biodiversity.
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Bivalves , Elementos de DNA Transponíveis , Evolução Molecular , Filogenia , Animais , Elementos de DNA Transponíveis/genética , Bivalves/genética , Bivalves/classificação , Fases de Leitura AbertaRESUMO
Proteins of the gelsolin family are Ca2+-dependent, multifunctional, actin-binding proteins containing three (S1-S3, about 40 kDa) or six (S1-S6, about 80 kDa) highly conserved repeats in the amino acid sequence. The pattern of interaction of these proteins with actin is complex: they can sever actin filaments; promote polymer nucleation after binding to two actin monomers; and cap the growing barbed end of actin filaments. In the present study, an actin polymerizing factor (46 kDa) from the adductor muscle of a bivalve mollusc has been discovered and identified for the first time. This protein has turned out to belong to the gelsolin family of actin regulatory proteins. The expression of gelsolin-like proteins in the tissues of bivalves was predicted after analyzing their proteome, but this is the first study where an actually expressed protein has been found. A primary determination of its physicochemical properties such as molecular weight, charge, resistance to urea, influence on actin polymerization by viscosity, and light scattering is carried out and the molecular structure analyzed.
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Actinas , Gelsolina , Gelsolina/metabolismo , Actinas/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Proteínas dos Microfilamentos/metabolismo , Músculo Esquelético/metabolismo , Cálcio/metabolismoRESUMO
BACKGROUND: The clam Chamelea gallina is an ecologically and economically important marine species in the Northwestern Adriatic Sea, which currently suffers from occasional, and still unexplained, widespread mortality events. In order to provide some glimpses in this direction, this study explores the connections between microbiome variations at the clam-sediment interface and the nutritional status of clams collected at four Italian production sites along the Emilia Romagna coast, with different mortality incidence, higher in the Northern sites and lower in the Southern sites. RESULTS: According to our findings, each production site showed a peculiar microbiome arrangement at the clam-sediment interface, with features that clearly differentiate the Northern and Southern sites, with the latter also being associated with a better nutritional status of the animal. Interestingly, the C. gallina digestive gland microbiome from the Southern sites was enriched in some health-promoting microbiome components, capable of supplying the host with essential nutrients and defensive molecules. Furthermore, in experiments conducted under controlled conditions in aquaria, we provided preliminary evidence of the prebiotic action of sediments from the Southern sites, allowing to boost the acquisition of previously identified health-promoting components of the digestive gland microbiome by clams from the Northern sites. CONCLUSIONS: Taken together, our findings may help define innovative microbiome-based management strategies for the preservation of the productivity of C. gallina clams in the Adriatic Sea, through the identification and maintenance of a probiotic niche at the animal-sediment interface.
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Bivalves , Animais , Alimentos MarinhosRESUMO
Omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) have many health benefits to human. Increasing evidence have shown that climate change reduces the availability of plankton n-3 LC-PUFA to primary consumers which potentially reduces the availability of n-3 LC-PUFA to human. Since marine bivalves are an important source of n-3 LC-PUFA for human beings, and bivalve aquaculture completely depends on phytoplankton in ambient water as food, it is important to understand the impact of climate change on the lipid nutritional quality of bivalves. In this study, fatty acid profile of different bivalves (mussels, oysters, clams, scallops and cockles) from different regions (tropical, subtropical and temperate) and time (before 1990, 1991-1995, 1996-2000, 2001-2005, 2006-2010, 2011-2015, 2016-2020) were extracted from published literature to calculate various lipid nutritional quality indicators. The results of this study revealed that the effects of global warming and declines in aragonite saturation state on the lipid content and lipid indices of bivalves are highly dependent on the geographical region and bivalves. In general, global warming has the largest negative impact on the lipid content and indices of temperate bivalves, including decreasing the PUFA/SFA, EPA + DHA and n-3/n-6. However, global warming has a much smaller negative impact on lipid content and lipid indices in other regions. The declines of aragonite saturation state in seawater promotes the accumulation of lipid content in tropical and subtropical bivalves, but it compromised the PUFA/SFA, EPA + DHA and n-3/n-6 of bivalves in all regions. The findings of this study not only fill the knowledge gap of the impact of climate change on the lipid nutritional quality of bivalves, but also provide guidance for the establishment of bivalve aquaculture and fisheries management plans to mitigate the impact of climate change.
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Mussels are constantly exposed to various pollutants in the environment, which can impair their immune defences against microbes and thus threaten their survival. In this study, we expand the insight into a key parameter of immune response in two mussel species by exploring the impact of exposure to pollutants or bacteria or simultaneous chemical and biological exposure on haemocyte motility. Basal haemocyte velocity in primary culture was high and increasing over time in Mytilus edulis (mean cell speed of 2.32 µm/min ± 1.57) whereas Dreissena polymorpha showed a constant and rather low cell motility with time (mean cell speed of 0.59 µm/min ± 0.1). In the presence of bacteria, the motility of haemocytes was instantly enhanced and slowed down after 90 min for M. edulis. In contrast, in vitro exposure of haemocytes to chemicals, either Bisphenol A, oestradiol, copper, or caffeine, induced an inhibition of cell motility in both mussel species. Finally, the cellular activation observed during bacterial challenges was inhibited by simultaneous exposure to bacteria and pollutants. Overall, our results indicate that chemical contaminants can alter haemocyte migration in mussels which can weaken their response to pathogens and therefore increase their susceptibility to infectious diseases.
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Dreissena , Mytilus edulis , Mytilus , Poluentes Químicos da Água , Animais , Cobre , Estresse Fisiológico , Poluentes Químicos da Água/toxicidadeRESUMO
As filter-feeding bivalves, mussels have been traditionally studied as possible vectors of different bacterial or viral pathogens. The absence of a known viral pathogen in these bivalves makes it particularly interesting to study the interaction of the mussel innate immune system with a virus of interest. In the present work, mussels were challenged with viral haemorrhagic septicaemia virus (VHSV), which is a pathogen in several fish species. The viral load was eliminated after 24 h and mussels evidenced antiviral activity towards VHSV, demonstrating that the virus was recognized and eliminated by the immune system of the host and confirming that mussels are not VHSV vectors in the marine environment. The transcriptome activating the antiviral response was studied, revealing the involvement of cytoplasmic viral sensors with the subsequent activation of the JAK-STAT pathway and several downstream antiviral effectors. The inflammatory response was inhibited with the profound downregulation of MyD88, shifting the immune balance towards antiviral functions. High modulation of retrotransposon activity was observed, revealing a mechanism that facilitates the antiviral response and that had not been previously observed in these species. The expression of several inhibitors of apoptosis and apoptosis-promoting genes was modulated, although clear inhibition of apoptosis in bivalves after severe viral infection and subsequent disease was not observed in this study. Finally, the modulated expression of several long noncoding RNAs that were correlated with genes involved in the immune response was detected.
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Doenças dos Peixes , Septicemia Hemorrágica Viral , Novirhabdovirus , Animais , Transcriptoma , Janus Quinases , Fatores de Transcrição STAT , Transdução de Sinais , Novirhabdovirus/fisiologia , Antivirais/farmacologiaRESUMO
Radiological contamination of coastal habitats poses potential risk for native fauna, but the bioavailability of aqueous radium (Ra) and other dissolved metals to marine bivalves remains unclear. This study was the first to examine the tissue-specific disposition of aqueous 226Ra in a coastal mussel, specifically the Atlantic ribbed mussel Geukensia demissa. Most organ groups reached steady-state concentrations within 7 days during experimental exposure, with an average uptake rate constant of 0.0013 mL g-1 d-1. When moved to Ra-free synthetic seawater, mussels rapidly eliminated aqueous 226Ra (average elimination rate constant 1.56 d-1). The biological half-life for aqueous 226Ra ranged from 8.9 h for the gills and labial palps to 15.4 h for the muscle. Although previous field studies have demonstrated notable 226Ra accumulation in the soft tissues of marine mussels and that, for freshwater mussels, tissue-incorporated 226Ra derives primarily from the aqueous phase, our tissue-specific bioconcentration factors (BCFs) were on the order of (8.3 ± 1.5) × 10-4 indicating low accumulation potential of aqueous 226Ra in estuarine mussels. This suggests marine and estuarine mussels obtain 226Ra from an alternate route, such as particulate-sorbed Ra ingested during filter-feeding or from a contaminated food source.