Increased microgastropoda sampling give new insights into the phylogenetic relationships of Littorinoidea (Littorinimorpha).

Littorinoidea is one of the most diverse radiations and the most successful group that evolutionary transitions from marine to terrestrial within Littorinimorpha. With such an unmatched diversity, few phylogenetic investigations have attempted to understand their evolutionary relationships, and existing research has primarily focused on typical intertidal species. To address this gap, we conducted the first phylogenomic analysis of the Littorinoidea, leveraging 35 transcriptomes to investigate their internal relationships. Our analyses revealed significant revisions necessary within the Littorinoidea: 1) Pomatias appears distantly related to Littorinidae, suggesting a potential ancestral origin outside of Littorinoidea, challenging traditional classification. The homology of penial innervation within Littorinoidea warrants reevaluation. 2) Lacuna's placement indicates a close relationship with Naticidae, prompting consideration for its removal from Littorinidae. 3) Based on the current phylogenetic research, Peasiella may belong to a distinct family separate from Littorinidae. 4) Our findings support revising the placement of Pteropods within the Littorinimorpha, which is situated phylogenetically between the families Littorinoidea and Naticoidea. Additionally, we highlight the impact of site heterogeneity and evolutionary rate variation on phylogenetic inference. Our study provides a robust phylogenomic framework for the Littorinoidea, emphasizing the importance of including microgastropoda taxa in molecular phylogenetic reconstructions of gastropod subgroups.

Multi-omic insights into the formation and evolution of a novel shell microstructure in oysters.

BACKGROUND: Molluscan shell, composed of a diverse range of architectures and microstructures, is a classic model system to study the relationships between molecular evolution and biomineralized structure formation. The shells of oysters differ from those of other molluscs by possessing a novel microstructure, chalky calcite, which facilitates adaptation to the sessile lifestyle. However, the genetic basis and evolutionary origin of this adaptive innovation remain largely unexplored. RESULTS: We report the first whole-genome assembly and shell proteomes of the Iwagaki oyster Crassostrea nippona. Multi-omic integrative analyses revealed that independently expanded and co-opted tyrosinase, peroxidase, TIMP genes may contribute to the chalky layer formation in oysters. Comparisons with other molluscan shell proteomes imply that von Willebrand factor type A and chitin-binding domains are basic members of molluscan biomineralization toolkit. Genome-wide identification and analyses of these two domains in 19 metazoans enabled us to propose that the well-known Pif may share a common origin in the last common ancestor of Bilateria. Furthermore, Pif and LamG3 genes acquire new genetic function for shell mineralization in bivalves and the chalky calcite formation in oysters likely through a combination of gene duplication and domain reorganization. CONCLUSIONS: The spatial expression of SMP genes in the mantle and molecular evolution of Pif are potentially involved in regulation of the chalky calcite deposition, thereby shaping the high plasticity of the oyster shell to adapt to a sessile lifestyle. This study further highlights neo-functionalization as a crucial mechanism for the diversification of shell mineralization and microstructures in molluscs, which may be applied more widely for studies on the evolution of metazoan biomineralization.

A chromosome-level genome assembly of Ostrea denselamellosa provides initial insights into its evolution.

The oyster Ostrea denselamellosa is a live-bearing species with a sharp decline in the natural population. Despite recent breakthroughs in long-read sequencing, high quality genomic data are very limited in O. denselamellosa. Here, we carried out the first whole genome sequencing at the chromosome-level in O. denselamellosa. Our studies yielded a 636 Mb assembly with scaffold N50 around 71.80 Mb. 608.3 Mb (95.6% of the assembly) were anchored to 10 chromosomes. A total of 26,412 protein-coding genes were predicted, of which 22,636 (85.7%) were functionally annotated. By comparative genomics, we found that long interspersed nuclear element (LINE) and short interspersed nuclear element (SINE) made up a larger proportion in O. denselamellosa genome than in other oysters'. Moreover, gene family analysis showed some initial insight into its evolution. This high-quality genome of O. denselamellosa provides a valuable genomic resource for studies of evolution, adaption and conservation in oysters.

Parallel evolution in Crassostrea oysters along the latitudinal gradient is associated with variation in multiple genes involved in adipogenesis.

Parallel diversification provides a proper framework for studying the role of natural selection in evolution. Yet, empirical studies from ecological 'non-model' species of invertebrates are limited at the whole genome level. Here, we presented a chromosome-scale genome assembly for Crassostrea angulata and investigated the parallel genomic evolution in oysters. Specifically, we used population genomics approaches to compare two southern-northern oyster species pairs (C. angulata-C. gigas and southern-northern C. ariakensis) along the coast of China. The estimated divergence time of C. angulata and C. gigas is earlier than that of southern and northern C. ariakensis, which aligns with the overall elevated genome-wide divergence. However, the southern-northern C. ariakensis FST profile represented more extremely divergent "islands". Combined with recent reciprocal hybridization studies, we proposed that they are currently at an early stage of speciation. These two southern-northern oyster species pairs exhibited significant repeatability in patterns of genome-wide differentiation, especially in genomic regions with extremely high and low divergence. This suggested that divergent and purifying selection has contributed to the genomic parallelism between southern and northern latitudes. Top differentiated genomic regions shared in these two oyster species pairs contained candidate genes enriched for functions in energy metabolism, especially adipogenesis, which are closely related to reproductive behaviours. These genes might be good candidates for further investigation in vivo. In conclusion, our results suggest that similar divergent selection and shared genomic features could predictably transform standing genetic variation within one species pair into differences in another.

A comparative analysis of mitochondrial ORFs provides new insights on expansion of mitochondrial genome size in Arcidae.

BACKGROUND: Arcidae, comprising about 260 species of ark shells, is an ecologically and economically important lineage of bivalve mollusks. Interestingly, mitochondrial genomes of several Arcidae species are 2-3 times larger than those of most bilaterians, and are among the largest bilaterian mitochondrial genomes reported to date. The large mitochondrial genome size is mainly due to expansion of unassigned regions (regions that are functionally unassigned). Previous work on unassigned regions of Arcidae mtDNA genomes has focused on nucleotide-level analyses to observe sequence characteristics, however the origin of expansion remains unclear. RESULTS: We assembled six new mitogenomes and sequenced six transcriptomes of Scapharca broughtonii to identify conserved functional ORFs that are transcribed in unassigned regions. Sixteen lineage-specific ORFs with different copy numbers were identified from seven Arcidae species, and 11 of 16 ORFs were expressed and likely biologically active. Unassigned regions of 32 Arcidae mitogenomes were compared to verify the presence of these novel mitochondrial ORFs and their distribution. Strikingly, multiple structural analyses and functional prediction suggested that these additional mtDNA-encoded proteins have potential functional significance. In addition, our results also revealed that the ORFs have a strong connection to the expansion of Arcidae mitochondrial genomes and their large-scale duplication play an important role in multiple expansion events. We discussed the possible origin of ORFs and hypothesized that these ORFs may originate from duplication of mitochondrial genes. CONCLUSIONS: The presence of lineage-specific mitochondrial ORFs with transcriptional activity and potential functional significance supports novel features for Arcidae mitochondrial genomes. Given our observation and analyses, these ORFs may be products of mitochondrial gene duplication. These findings shed light on the origin and function of novel mitochondrial genes in bivalves and provide new insights into evolution of mitochondrial genome size in metazoans.

Effects of low salinity on hemolymph osmolality and transcriptome of the Iwagaki oyster, Crassostrea nippona.

Crassostrea nippona is a kind of oysters with great development value as it can be edible in summer for its late reproductive period. Salinity is one of the important limiting abiotic factors to the survival and distribution of this stenohaline species. To better understand the physiological and immunological response of C. nippona to varying environmental salinities, the effects of low salinity on the hemolymph osmolality and gill transcriptome were investigated in this study. The osmolality of hemolymph in vivo and surrounding water were assessed regularly over one week at five test salinities ranging from 5 psµ to 30 psµ. They reached osmotic equilibrium within hours above 15 psµ but remained hyperosmotic at 10 and 5 psµ for the whole sampling period. Through comparative transcriptome analysis, there were less differentially expressed genes (DEGs) in pairwise comparison of S1 (10 psµ) vs S3 (30 psµ) than in S2 (20 psµ) vs S3. KEGG enrichment analysis identified ubiquitin-mediated proteolysis and mitochondrial apoptosis pathway specifically enriched at 10 psµ. This study gained comprehensive insights on the low salinity response of C. nippona at the molecular level, which provide a theoretical basis for understanding the immune mechanism under low salinity stress.

A novel use of small ballons to reduce the risk of subintimal hematoma formation during recanalization of chronic total occlusion: two case reports.

BACKGROUND: Subintimal hematoma remains a major challenge associated with unnecessary technical complexity, failure of the antegrade approach or imperfection of revascularization in percutaneous coronary intervention (PCI) for chronic total occlusion (CTO). Some techniques and devices release the hematoma after its formation. Here, we describe a novel use of small ballons to prevent the hematoma formation during antegrade approach in two cases. CASE PRESENTATION: We report two cases of CTO-PCI in which balloon occlusion was successfully applied to prevent haematoma formation. The first case, a 72-year-old female with diabetes, was hospitalized because of unstable angina. Angiography showed right coronary artery (RCA) CTO, which initiated from the proximal part to the trifurcation at the distal part of the RCA. Considering the high likelihood and serious consequences of subintimal haematoma, a small balloon is employed to prevent subintimal hematoma formation. A balloon and microcatheter or double-lumen microcatheter are placed in the proximal coronary CTO lesion; then the balloon was dilated beside the catheter, most of the antegrade blood flow was sealed which reduced the likelihood of haematoma formation. The procedure was successfully completed without subintimal hematoma formation. The second case a 62-year-old male with unstable angina, was hospitalized for PCI. Angiography showed left anterior descending coronary artery CTO. Similar to case 1, we also used a small balloon to prevent hematoma formation. Both patients underwent PCI, which employed a small balloon to prevent hematoma formation and both procedures were successful without complications. CONCLUSION: In patients who underwent CTO-PCI, balloon occlusion offers an alternative for reducing the incidence of subintimal haematomas.

Porous Structure of ß-Cyclodextrin for CO2 Capture: Structural Remodeling by Thermal Activation.

With a purpose of extending the application of ß-cyclodextrin (ß-CD) for gas adsorption, this paper aims to reveal the pore formation mechanism of a promising adsorbent for CO2 capture which was derived from the structural remodeling of ß-CD by thermal activation. The pore structure and performance of the adsorbent were characterized by means of SEM, BET and CO2 adsorption. Then, the thermochemical characteristics during pore formation were systematically investigated by means of TG-DSC, in situ TG-FTIR/FTIR, in situ TG-MS/MS, EDS, XPS and DFT. The results show that the derived adsorbent exhibits an excellent porous structure for CO2 capture accompanied by an adsorption capacity of 4.2 mmol/g at 0 °C and 100 kPa. The porous structure is obtained by the structural remodeling such as dehydration polymerization with the prior locations such as hydroxyl bonded to C6 and ring-opening polymerization with the main locations (C4, C1, C5), accompanied by the release of those small molecules such as H2O, CO2 and C3H4. A large amount of new fine pores is formed at the third and fourth stage of the four-stage activation process. Particularly, more micropores are created at the fourth stage. This revealed that pore formation mechanism is beneficial to structural design of further thermal-treated graft/functionalization polymer derived from ß-CD, potentially applicable for gas adsorption such as CO2 capture.

Evolution of mitochondrial gene arrangements in Arcidae (Bivalvia: Arcida) and their phylogenetic implications.

Arcidae is a diverse group of ark shells with over 260 described species. The phylogenetic relationships and the evolution of the mitochondrial genomes in this family were poorly understood. Comparisons of mitogenomes have been widely used to explore the phylogenetic relationship among animal taxa. We described the complete mitogenomes of Arca navicularis, Scapharca gubernaculum and one nearly complete mitogenome of Anadara consociata. The mitogenome of A. navicularis (18,103 bp) is currently the smallest known Arcidae mitogenome, while the mitogenomes of S. gubernaculum (45,697 bp) and A. consociata (44,034 bp) are relatively large. The mitochondrial gene orders of the three taxa were substantially different from each other, as well as the patterns found in other ark shells. The relationships among Arcidae species recovered from different mitochondrial characters (nucleotide sequence versus gene order) were in disagreement. The phylogeny based on nucleotide sequences did not support the monophyly of Arcidae, as Cucullaea labiata (Cucullaeidae) appeared as a subgroup within Arcinae, rather than sister group to the family Arcidae. In addition, we presented the first time-calibrated evolutionary tree of Arcidae based on mitochondrial DNA (mtDNA) sequences, which placed the deepest divergence within Arcidae at 342.36 million years ago (Mya), around the Carboniferous (360-300 Mya).

Mitogenomics reveals phylogenetic relationships of Arcoida (Mollusca, Bivalvia) and multiple independent expansions and contractions in mitochondrial genome size.

Arcoida, comprising about 570 species of blood cockles, is an ecologically and economically important lineage of bivalve molluscs. Current classification of arcoids is largely based on morphology, which shows widespread homoplasy. Despite two recent studies employing multi-locus analyses with broad sampling of Arcoida, evolutionary relationships among major lineages remain controversial. Interestingly, mitochondrial genomes of several ark shell species are 2-3 times larger than those found in most bilaterians, and are among the largest bilaterian mitochondrial genomes reported to date. These results highlight the need of detailed phylogenetic study to explore evolutionary relationships within Arcoida so that the evolution of mitochondrial genome size can be understood. To this end, we sequenced 17 mitochondrial genomes and compared them with publicly available data, including those from other lineages of Arcoida with emphasis on the subclade Arcoidea species. Our phylogenetic analyses indicate that Noetiidae, Cucullaeidae and Glycymerididae are nested within a polyphyletic Arcidae. Moreover, we find multiple independent expansions and potential contractions of mitochondrial genome size, suggesting that the large mitochondrial genome is not a shared ancestral feature in Arcoida. We also examined tandem repeats and inverted repeats in non-coding regions and investigated the presence of such repeats with relation to genome size variation. Our results suggest that tandem repeats might facilitate intraspecific mitochondrial genome size variation, and that inverted repeats, which could be derived from transposons, might be responsible for mitochondrial genome expansions and contractions. We show that mitochondrial genome size in Arcoida is more dynamic than previously understood and provide insights into evolution of mitochondrial genome size variation in metazoans.

Molecular Species Delimitation of the Genus Reishia (Mollusca: Gastropoda) along the Coasts of China and Korea.

Species of the predatory gastropod genus Reishia Kuroda and Habe, 1971 (Muricidae) inhabit intertidal rocky shores in East Asia. Due to their highly variable external shell morphology, the taxonomy of this genus at species-level is still in need of re-evaluation. Using DNA-based delimitation methods, we aimed to ascertain the number of species of Reishia along the coasts of China and adjacent Asian areas. Also, we looked for diagnostic traits using morphology-based statistical approaches. Our genetic data suggest that the studied individuals comprised two separate species of a Reishia complex in this region, in contrast to the previously proposed four or more taxa. This conclusion is further supported by statistical analyses of shell morphological characteristics. The morphospecies R. bronni (Dunker, 1860), R. jubilaea (Tan and Sigurdsson, 1990), and R. luteostoma (Holten, 1803) were assigned to a single taxon, indicating that they might be synonyms of the same species. The morphospecies R. clavigera (Küster, 1860) singly formed one group, suggesting that it is likely a valid name. The estimated divergence time of the two identified taxa indicates that speciation might have been associated with the sea level and temperature fluctuations during the Plio-Pleistocene period. Our study on Reishia species provides crucial information for further research on the ecology, evolutionary biology, and conservation of this genus.

Complete Mitochondrial Genomes of Two Toxin-Accumulated Nassariids (Neogastropoda: Nassariidae: Nassarius) and Their Implication for Phylogeny.

The Indo-Pacific nassariids (genus Nassarius) possesses the highest diversity within the family Nassariidae. However, the previous shell or radula-based classification of Nassarius is quite confusing due to the homoplasy of certain morphological characteristics. The toxin accumulators Nassarius glans and Nassarius siquijorensis are widely distributed in the subtidal regions of the Indo-Pacific Ocean. In spite of their biological significance, the phylogenetic positions of N. glans and N. siquijorensis are still undetermined. In the present study, the complete mitochondrial genomes of N. glans and N. siquijorensis were sequenced. The present mitochondrial genomes were 15,296 and 15,337 bp in length, respectively, showing negative AT skews and positive GC skews as well as a bias of AT rich on the heavy strand. They contained 13 protein coding genes, 22 transfer RNA genes, two ribosomal RNA genes, and several noncoding regions, and their gene order was identical to most caenogastropods. Based on the nucleotide sequences combining 13 protein coding genes and two rRNA genes, a well-supported phylogeny of Nassarius was reconstructed, and several morphological synapomorphies were observed corresponding to the phylogenetic framework. In addition, the sister group relationship between N. variciferus and the remaining toxin-accumulated nassariids was determined, suggesting that the phylogeny might be related to their diet. The divergence time estimation analysis revealed a correlation between speciation events of nassariids and glacial cycles during the Pliocene-Pleistocene epoch.

Multiple reversals of strand asymmetry in molluscs mitochondrial genomes, and consequences for phylogenetic inferences.

Strand asymmetry in nucleotide composition is a remarkable feature of animal mitochondrial genomes. The strand-specific bias in the nucleotide composition of the mtDNA has been known to be highly problematic for phylogenetic analyses. Here, the strand asymmetry was compared across 140 mollusc species and analyzed for a mtDNA fragment including twelve protein-coding genes. The analyses show that almost all species in Gastropoda (except Heterobranchia) and all species in Bivalvia present reversals of strand bias. The skew values on individual genes for all codon positions (P123), third codon positions (P3), and fourfold redundant third codon positions (P4FD) indicated that CG skews are the best indicators of strand asymmetry. The differences in the patterns of strand asymmetry significantly influenced the amino acid composition of the encoded proteins. These biases are most striking for the amino acids Valine, Cysteine, Asparagine and Threonines, which appear to have evolved asymmetrical exchanges in response to shifts in nucleotide composition. Molluscs with strong variability of genome architectures (ARs) are usually characterized by a reversal of the usual strand bias. Phylogenetic analyses show that reversals of asymmetric mutational constraints have consequences on the phylogenetic inferences, as taxa characterized by reverse strand bias (Heterobranchia and Bivalvia) tend to group together due to long-branch attraction (LBA) artifacts. Neutral Transitions Excluded (NTE) model did not overcome the problem of heterogeneous biases present in molluscs mt genomes, suggested it may not be appropriate for molluscs mt genome data. Further refinement phylogenetic models may help us better understand internal relationships among these diverse organisms.

Atorvastatin blocks increased l-type Ca2+ current and cell injury elicited by angiotensin II via inhibiting oxide stress.

Thel-type Ca(2+)current (ICa,l) plays a crucial role in shaping action potential and is involved in cardiac arrhythmia. Statins have been demonstrated to contribute to anti-apoptotic and anti-arrhythmic effects in the heart. Here, we examined whether atorvastatin regulates theICa,land cell injury induced by angiotensin II (AngII) as well as the putative intracellular cascade responsible for the effects. Cultured neonatal rat ventricular myocytes were incubated with AngII for 24 h, and then cell injury and expression levels of Nox2/gp91(phox), p47(phox) ,and Cav1.2 were analyzed. In addition,ICa,lwas recorded using the whole-cell patch-clamp technique, and mechanisms of atorvastatin actions were also investigated. It was found that the number of apoptotic cardiomyocytes was increased and cell viability was significantly decreased after AngII administration. AngII also augmented the expressions of Nox2/gp91(phox)and p47(phox)compared with control cardiomyocytes. Exposure to AngII evokedICa,lin a voltage-dependent manner without affecting theI-Vrelationship. In addition, AngII enhanced membrane Cav1.2 expression. These effects were abolished in the presence of the reactive oxygen species (ROS) scavenger, manganese (III)-tetrakis 4-benzoic acid porphyrin [Mn(III)TBAP], or the 3-hydroxy-3-methylglutaryl-CoA reductase inhibitor, atorvastatin. These results suggested that atorvastatin mediates cardioprotection against arrhythmias and cell injury by controlling the AngII-ROS cascade.

Molecular phylogeny of Arcoidea with emphasis on Arcidae species (Bivalvia: Pteriomorphia) along the coast of China: challenges to current classification of arcoids.

The current classifications of arcoids are based on phenetic similarity, which display considerable convergence in several shell and anatomical characters, challenging phylogenetic analysis. Independent molecular analysis of DNA sequences is often necessary for accurate taxonomic assignments of arcoids, especially when morphological characters are equivocal. Here we present molecular evidence of the phylogenetic relationships among arcoid species based on Bayesian inference and Maximum Likelihood analyses of three nuclear genes (18SrRNA, 28SrRNA, and histone H3) and two mitochondrial genes (COI and 12S). Tree topologies are discussed by considering traditional arrangements of taxonomic units and previous molecular studies. The results confirm the monophyly of the order Arcoida, the family Noetiidae, and the subfamilies Anadarinae and Striarcinae, with support for the inclusion of the Glycymerididae in the Arcoidea. The subfamily Arcinae and the genera Arca, Barbatia, Scapharca, Anadara, and Glycymeris are non-monophyletic, suggesting that taxonomic issues still remain. The families Noetiidae, Cucullaeidae, and Glycymerididae appear as subgroups within, rather than sister groups to, the Arcidae. This study strongly suggests the need to carry out a taxonomic revision of the Arcoidea, especially the Arcidae, through combined analysis of morphological, paleontological, and molecular data.

Apolipoprotein-J prevents angiotensin II-induced apoptosis in neonatal rat ventricular cells.

BACKGROUND: Up-regulation of angiotensin II (AngII) occurs in cardiac diseases, such as congestive heart failure, cardiac hypertrophy, myocardial ischemia and atrial fibrillation, which represent major health problems. Evidence from in vivo studies suggests that the level of Apolipoprotein-J (ApoJ) is also elevated but plays a protective role in cardiovascular disease. This study aimed to evaluate the protective effects of ApoJ against cytotoxicity of AngII in neonatal rat ventricular cells (NRVCs). METHODS AND RESULTS: In culture, NRVCs were damaged by exposure to AngII, and ApoJ overexpression using an adenovirus vector significantly reduced the AngII-induced cell injury. ApoJ also prevented AngII from augmenting Nox2/gp91(phox) expression. The reactive oxygen species (ROS) scavenger, Mn(III)TBAP, showed similar results of attenuating AngII-induced cell damage. Furthermore, ApoJ overexpression increased phosphorylation of Akt, and the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 diminished the antioxidant effects of ApoJ, and prevented the protective effect of ApoJ against the cytotoxicity of AngII. Moreover, upregulation of nuclear factor κB (NF-κB) p65 expression and phosphorylation of p38 mitogen-activated protein kinase (MAPK) mediated by AngII in cultured NRVCs were significantly inhibited by overexpression of ApoJ. The p38 MAPK inhibitor SB203580 and the NF-κB inhibitor PDTC protected NRVCs from injury caused by AngII. CONCLUSIONS: ApoJ serves as a cytoprotective protein in NRVCs against cytotoxicity of AngII through the PI3K-Akt-ROS and MAPK/ NF-κB pathways.

Comparative phylogeography in marginal seas of the northwestern Pacific.

The maturation of marine phylogeography depends on integration of comparative information across different regions globally. The northwestern Pacific, characterized by unique tectonic setting, however, is still underrepresented. This study seeks to highlight its phylogeographical history based on the available population data, focusing on three seas: the East China Sea (ECS), the South China Sea (SCS) and the Sea of Japan (SOJ). We first conducted a literature survey to evaluate current research efforts and then reanalysed the population structure, historical demography and genealogy for two selections of studies (namely 'the ECS category' and 'the multiple-sea category') to elucidate the evolutionary processes within and across the seas, respectively. For the ECS category, the meta-analyses revealed most studies displayed a shallow phylogeny, indicating a single origin from the sea. Significant population structure was commonplace, particularly in molluck and crustacean studies, with proportions of 89% and 80%, respectively. Nearly all studies selected showed signals of population expansion: the times estimated were closely linked to a period of ~120-140 Kya rather than the last glacial maximum. For the latter category, divergent intraspecific lineages appeared among seas and overlapped in the adjacent regions, a pattern implying each sea had served as an independent refugium during glaciations. The genetic splits, however, were estimated to arise from separate events dating from late Miocene to middle Pleistocene. As phylogeography is still in its infancy in the region, more effort is needed to test and complement the general rules abstracted here. Finally, challenges and prospects were discussed to accelerate further research.

Molecular cloning and differential expression in tissues of a tyrosinase gene in the Pacific oyster Crassostrea gigas.

Tyrosinases are a group of type-3 copper proteins that catalyze the first two reactions in the melanin biosynthesis in organisms ranging from bacteria, fungi, plants to animals. Tyrosinases are not only involved in pigmentation, but also play an important role in the innate immunity in invertebrates. Additionally, tyrosinases are also known to be involved in the biogenesis and pigmentation of shells. The recently published Crassostrea gigas genome sequences revealed that the Pacific oyster possesses at least 26 tyrosinase isoforms. However, their molecular features are largely understudied. In fact, the full-length mRNA sequence was determined for one of the tyrosinase genes (i.e., CgTry1; aka cgi-tyr1). Here we report the full-length transcript of a second C. gigas tyrosinase (CgTyr2) sequence and the determination of its sequence features characteristic to the tyrosinase family proteins. We also showed that CgTyr2 gene was differentially expressed with the highest level of expression in mantle edges, suggesting its potential role in the formation of periostracum/pigmentation. Our comprehensive phylogenetic reconstructions supported that hemocyanins possibly evolved from a tyrosinase by an ancient gene duplication followed by functional differentiation, and the current large number of tyrosinase isoforms in C. gigas and other mollusks were originated from multiple gene duplication events that took places before and after mollusk species were established.

[Phylogenetic analysis of tyrosinase gene family in the Pacific oyster (Crassostrea gigas Thunberg)].

The deduced amino acid sequence characteristics, classification and phylogeny of tyrosinase gene family in the Pacific oyster (Crassostrea gigas Thunberg) were analyzed using bioinformatics methods. The results showed that gene duplication was the major cause of tyrosinase gene expansion in the Pacific oyster. The tyrosinase gene family in the Pacific oyster can be further classified into three types: secreted form (Type A), cytosolic form (Type B) and membrane-bound form (Type C). Based on the topology of the phylogenetic tree of the Pacific oyster tyrosinases, among Type A isoforms, tyr18 seemed divergent from other Type A tyrosinases early, while tyr2 and tyr9 appeared divergent early in Type B. In Type C tyrosinses, tyr8 was divergent early. The cluster of the Pacific oyster tyrosinasesis determined by their classifications and positions in the scaffolds. Further analysis suggested that Type A tyrosinases of C. gigas clustered with those from cephalopods and then with nematodes and cnidarians. Type B tyrosinases were generally clustered with the same type of tyrosinases from molluscas and nematodes, and then with those from platyhelminths, cnidarians and chordates. Type A tyrosinases in the Pacific oyster and the Pearl oyster expanded independently and were divergent from membrane-bound form of tyrosinases in chordata, platyhelminthes and annelida. These observations suggested that Type C tyrosinases in the bivalve had a distinct evolution direction.

First record of the genus Conotalopia Iredale, 1929 (Vetigastropoda, Trochidae) in China.

Background: The genus Conotalopia Iredale, 1929 consisting of marine trochids, primarily inhabits the intertidal zone. Globally, eight recent species have been documented, all of which occur in the Pacific Region. The genus has not previously been recorded from Chinese seas. New information: This study fills a knowledge gap by reporting, for the first time, the presence of the trochid genus Conotalopia Iredale, 1929 in China. Specifically, Conotalopiasematensis (Oyama, 1942) was detailed using morphological characteristics derived from the shell (Fig. 1A-F and H-I), operculum (Fig. 1G) and radula (Fig. 1J-L). Additionally, this study introduces comprehensive scanning electron microscope illustrations and molecular data, contributing valuable taxonomic information for the first time.