Genomic and Proteomic Analyses of Extracellular Products Reveal Major Virulence Factors Likely Accounting for Differences in Pathogenicity to Bivalves between Strains.

, a bacterial pathogen of bivalves, has exhibited strain-dependent virulence. The mechanisms behind the variations in bivalve pathogenicity between strains have remained unclear. However, a preliminary analysis of the extracellular product (ECP) proteomes has revealed differences in protein compositions between low- and high-virulence strains; in addition to 1265 shared proteins, 127 proteins have been identified to be specific to one low-virulence strain and 95 proteins to be specific to two high-virulence strains.

Acute Salinity Stress Disrupts Gut Microbiota Homeostasis and Reduces Network Connectivity and Cooperation in Razor Clam Sinonovacula constricta.

Accumulating evidence demonstrates that it is of great importance to maintain a stable and functional gut microbial community for host's growth and health. However, gut microenvironment is constantly affected by diverse environmental factors. Salinity can cause stress, including hypersaline or hyposaline stress to aquatic species, thereby affecting their growth conditions.

Genome-Wide Analysis of Family I84 Protease Inhibitor Genes in Three Bivalves Reveals Important Information About the Protein Family's Evolution.

Family I84 serine protease inhibitors are believed to be mollusk specific proteins involved in host defense. The molecular evolution of the family, however, remains to be understood. In this study, the genes of Family I84 protease inhibitors in 3 bivalves, Crassostrea gigas, Crassostrea virginica and Tegillarca granosa, were analyzed at the genomic level.

Characterization of Vibrio mediterranei Isolates as Causative Agents of Vibriosis in Marine Bivalves.

Marine bivalves include species important globally for aquaculture and estuary ecology. However, epizootics of variable etiologies often pose a threat to the marine fishery industry and ecosystem by causing significant mortalities in related species. One of such diseases is larval vibriosis caused by bacteria of the genus , which frequently occurs and causes mass mortalities in bivalve larvae and juveniles in hatcheries.

Transcriptomic identification of key genes in Pacific oysters Crassostrea gigas responding to major abiotic and biotic stressors.

Oysters are commercially important intertidal filter-feeding species. Mass mortality events of oysters often occur due to environmental stresses, such as exposure to fluctuating temperatures, salinity, and air, as well as to metal pollution and pathogen infection. Here, RNA-seq data were used to identify shared and specific responsive genes by differential gene expression analysis and weighted gene co-expression network analysis.

Changes in Bacterial Communities of Kumamoto Oyster Larvae During Their Early Development and Following Vibrio Infection Resulting in a Mass Mortality Event.

Vibrio and Ostreid herpesvirus 1 are responsible for mass mortalities of oyster larvae in hatcheries. Relevant works have focused on their relationships with the disease when larval mortality occurs. On the contrary, little is known about how the resident microbiota in oyster larvae responds to Vibrio-infected disease causing mortality as the disease progressed, whereas this knowledge is fundamental to unveil the etiology of the disease.

Bacterial Community Dynamics in Kumamoto Oyster Hatchery During Larval Development.

Increasing evidence indicates that microbes colonized in early life stages have a long-term effect on animal wellbeing in later life stages. Related research is still limited in aquatic animals, particularly in bivalve mollusks. In this study, we analyzed the dynamics of the bacterial composition of the pelagic larval stages (fertilized egg, trochophore, D-stage, veliger, and pediveliger) and the sessile postlarval stage (spat) of Kumamoto oyster () and their relationships with the rearing water bacterioplankton in a hatchery by using Illumina sequencing of bacterial 16S rRNA gene.

Genome Wide Identification and Expression Profiling Indicate Expansion of Family I84 Protease Inhibitor Gene Tandem Duplication and Divergence in Razor Clam .

Family I84 protease inhibitors represent a novel family in the MEROPS peptidase database and are likely unique for molluscan host defense. Two Family I84 members, and , were reported from the razor clam in a previous research. In the present study, 12 additional genes, named to , were identified genome wide sequence analyses.

Genome-wide identification and characterization of superoxide dismutases in four oyster species reveals functional differentiation in response to biotic and abiotic stress.

Background: Oysters inhabit in the intertidal zone and may be suffered from environmental stresses, which can increase the production of reactive oxygen species (ROS), resulting in mass mortality. Superoxide dismutases (SODs) protect oysters from ROS damage through different mechanisms compared with vertebrates. However, the molecular and functional differentiation in oyster SODs were rarely analyzed.

Molecular characterization of two CuZn-SOD family proteins in the Pacific oyster Crassostrea gigas.

Superoxide dismutases (SOD) are multifamily antioxidant enzymes, playing an important role in the defense against oxidative stress in all organisms. Genomic information indicated the presence of genetic diversification of the copper and zinc SOD (CuZn-SOD) family in oysters. In the present research, we characterized two CuZn-SOD family proteins, Cg-CuZn-SOD and Cg-dominin3, in the Pacific oyster Crassostrea gigas using comprehensive sequence analyses, recombinant proteins and site-directed mutagenesis, and observations of gene expression in larval and adult oysters.

The complete mitochondrial genome of Crassostrea hongkongensis from East China Sea indicates species' range may extend northward.

Background: Crassostrea hongkongensis is an important mariculture shellfish with a relatively narrow distribution range. Recently, larger wild oysters were identified as C. hongkongensis from Sanmen bay in East China Sea.

Molecular Basis of Taste and Micronutrient Content in Kumamoto Oysters () and Portuguese Oysters () From Xiangshan Bay.

Oysters are the most extensively cultivated bivalves globally. Kumamoto oysters, which are sympatric with Portuguese oysters in Xiangshan bay, China, are regarded as particularly tasty. However, the molecular basis of their characteristic taste has not been identified yet.

Family I84 protease inhibitors likely constitute a Mollusca-specific protein family functioning in host defense.

Protease inhibitors are proteins or small polypeptides functioning in numerous biological processes in all organisms. The I84 family of protease inhibitors in the MEROPS database represents a novel protease inhibitor family that has been reported in 2 bivalves, Crassostrea virginica and Sinonovacula constricta, and is believed to play a role in host defense. In the present study, 7 new members of Family I84 were identified in 2 bivalves, Meretrix meretrix and Mytilus galloprovincialis, and 1 gastropod, Haliotis discus hannai, at the mRNA level via cDNA cloning.

Genomic Insights into the Origin and Evolution of Molluscan Red-Bloodedness in the Blood Clam Tegillarca granosa.

Blood clams differ from their molluscan kins by exhibiting a unique red-blood (RB) phenotype; however, the genetic basis and biochemical machinery subserving this evolutionary innovation remain unclear. As a fundamental step toward resolving this mystery, we presented the first chromosome-level genome and comprehensive transcriptomes of the blood clam Tegillarca granosa for an integrated genomic, evolutionary, and functional analyses of clam RB phenotype. We identified blood clam-specific and expanded gene families, as well as gene pathways that are of RB relevant.

Pathogen proteases and host protease inhibitors in molluscan infectious diseases.

The development of infectious diseases represents an outcome of dynamic interactions between the disease-producing agent's pathogenicity and the host's self-defense mechanism. Proteases secreted by pathogenic microorganisms and protease inhibitors produced by host species play an important role in the process. This review aimed at summarizing major findings in research on pathogen proteases and host protease inhibitors that had been proposed to be related to the development of mollusk diseases.

Dominin and Segon Form Multiprotein Particles in the Plasma of Eastern Oysters () and Are Likely Involved in Shell Formation.

Dominin and segon are two proteins purified and characterized from the plasma of eastern oysters , making up about 70% of the total plasma proteins. Their proposed functions are in host defense based on their pathogen binding properties and in metal metabolism based on their metal binding abilities. In the present study, the two proteins were further studied for their native states in circulation and extrapallial fluid and their possible involvement in shell formation.

Testing plasma subtilisin inhibitory activity as a selective marker for dermo resistance in eastern oysters.

Recent findings have suggested that eastern oyster plasma possesses inhibitors of the protease subtilisin, which play a role in the host defense against Perkinsus marinus, a protist parasite causing dermo. A study was conducted to determine whether plasma subtilisin inhibitory activity (PSIA) could be used as a selective marker in breeding programs for dermo resistance. Eastern oysters Crassostrea virginica from 2 wild Louisiana populations shown to differ in dermo resistance were collected and their PSIA was measured.

Two I84 family protease inhibitors from Chinese razor clams Sinonovacula constricta expressed in response to environmental challenges.

Protease inhibitors play critical roles in numerous biological processes including host defense in all multicellular organisms. Eighty three evolutionary families of protease inhibitors are currently accommodated in the MEROPS database and the I84 family currently consists of 3 novel serine protease inhibitors from the eastern oyster Crassostrea virginica. In this study, we identified 2 new I84 family members from the Chinese razor clam Sinonovacula constricta, scSI-1 and scSI-2, using cDNA cloning and sequencing.

Hemoglobins Likely Function as Peroxidase in Blood Clam Hemocytes.

Hemoglobins are a group of respiratory proteins principally functioning in transport of oxygen and carbon dioxide in red blood cells of all vertebrates and some invertebrates. The blood clam is one of the few invertebrates that have hemoglobin-containing red hemocytes. In the present research, the peroxidase activity of hemoglobins (Tg-Hbs) was characterized and the associated mechanism of action was deciphered via structural comparison with other known peroxidases.

Identification of cvSI-3 and evidence for the wide distribution and active evolution of the I84 family of protease inhibitors in mollusks.

Protease inhibitors are an extremely diverse group of proteins that control the proteolytic activities of proteases and play a crucial role in biological processes including host defenses. The I84 family of protease inhibitors in the MEROPS database currently consists of cvSI-1 and cvSI-2, two novel serine protease inhibitors purified and characterized from the eastern oyster Crassostrea virginica plasma and believed to play a role in host defense and disease resistance. In the present study, a third member of I84 family, named cvSI-3, was identified from C.

Astakine LvAST binds to the β subunit of F1-ATP synthase and likely plays a role in white shrimp Litopeneaus vannamei defense against white spot syndrome virus.

Cytokines play a critical role in innate and adaptive immunity. Astakines represent a group of invertebrate cytokines that are related to vertebrate prokineticin and function in promoting hematopoiesis in crustaceans. We have identified an astakine from the white shrimp Litopeneaus vannamei and named it LvAST in a previous research.

Three in one: Identification, expression and enzymatic activity of lysozymes in amphioxus.

The lysozymes identified so far in animals belong to the g-type, c-type, and i-type. Vertebrate animals possess only the former two types, i.e.

Identification of a novel metal binding protein, segon, in plasma of the eastern oyster, Crassostrea virginica.

The second most abundant protein of eastern oyster plasma was purified, characterized and named segon. The 39 kDa protein as determined by SDS-PAGE under reducing conditions made up about 17% of plasma proteins and was found in extrapallial fluid. RACE reactions with primers designed from an EST sequence identified by BLAST search in GenBank using the N-terminal amino acid sequence obtained by Edman degradation of the purified protein, predicted a 997 bp complete cDNA that encoded 277 amino acids including a 16-residue signal peptide at the N-terminus.