Yesso Scallop Mizuhopecten Yessoensis Research Articles

Genomic diversity of wild and cultured Yesso scallop Mizuhopecten yessoensis from Japan and Canada.

The Yesso scallop Mizuhopecten yessoensis is an important aquaculture species that was introduced to Western Canada from Japan to establish an economically viable scallop farming industry. This highly fecund species has been propagated in Canadian aquaculture hatcheries for the past 40 years, raising questions about genetic diversity and genetic differences among hatchery stocks. In this study, we compare cultured Canadian and wild Japanese populations of Yesso scallop using double-digest restriction site-associated DNA (ddRAD) sequencing to genotype 21,048 variants in 71 wild-caught scallops from Japan, 65 scallops from the Vancouver Island University breeding population, and 37 scallops obtained from a commercial farm off Vancouver Island, British Columbia. The wild scallops are largely comprised of equally unrelated individuals, whereas cultured scallops are comprised of multiple families of related individuals. The polymorphism rate estimated in wild scallops was 1.7%, whereas in the cultured strains, it ranged between 1.35 and 1.07%. Interestingly, heterozygosity rates were highest in the cultured populations, which is likely due to shellfish hatchery practices of crossing divergent strains to gain benefits of heterosis and to avoid inbreeding. Evidence of founder effects and drift was observed in the cultured strains, including high genetic differentiation between cultured populations and between cultured populations and the wild population. Cultured populations had effective population sizes ranging from 9 to 26 individuals whereas the wild population was estimated at 25,048-56,291 individuals. Further, a depletion of low-frequency variants was observed in the cultured populations. These results indicate significant genetic diversity losses in cultured scallops in Canadian breeding programs.

The Disease of the Scallop <i>Mizuhopecten yessoensis</i> (Jay, 1857) in the Mariculture Farms of Prymorye Caused by Protozoa of the Genus <i>Perkinsus</i> Levine, 1978

The results of a study of the cultivated yesso scallop Mizuhopecten yessoensis (Jay, 1857) in Primorsky Krai in 2014–2021 are presented. The death of molluscs in mariculture farms was noted, the symptoms of the “dermo” disease were studied: high mortality of scallops that have reached two years of age, observed during autumn displacement into new cages in September, the presence of protozoa of the genus Perkinsus Levine, 1978 in the tissues of organs, foci of damage of the adductor muscle, non-closure of the shell valves, black discoloration, necrotizing of soft tissues. The minimum level of the parasitic load was established: 10–15 pa-rasitic hypnospores per mollusc. However, considering the danger of a disease that causes mass death of molluscs for several years, the rapid spread of the pathogen, significant economic losses, it is recommended to create a specialized laboratory in the region for diagnosing and constantly monitoring the state of mariculture farms.

Effects of temperature, salinity, and food availability on shell growth rates of the Yesso scallop.

Shell growth rates in relationship to seasonal changes of environmental factors were studied in a wild population of the Yesso scallop Mizuhopecten yessoensis inhabiting Amur Bay (Peter the Great Bay, Sea of Japan, Russia). It was found that food availability is not a limiting factor for the scallop growth in the study area. A phytoplankton biomass of 3.5-6.0 g m-3 provided high scallop growth rates. The largest daily shell increments were observed with a phytoplankton biomass of about 6 g m-3. With a decrease in the phytoplankton biomass to <2 g m-3, as well as with an increase to >11 g m-3, the daily shell increments reduced. It appeared that the main exogenous factors causing the seasonal variations in the scallop growth rates are the water temperature, which was too high in July and August (>18°C) and too low in November-April (<4°C), and the water salinity, which was too low (<30‰) for this stenohaline species in summer. The relationship of the daily shell increment in Yesso scallop with the water temperature can be described by a dome-shaped curve. The largest increments were observed at 8-16°C. The dependence of the daily shell increments on the water salinity was also best described by a dome-shaped curve, showing the optimal range of 32.5-33.5‰. The revealed relationships, approximated by dome-shaped curves, evidently indicate that both insufficient and excessive effect of the factor negatively affects scallop growth. A suggestion was made to describe the result of the combined impact of several environmental factors on the daily shell increment as a multiplication of the functions of its dependence on each of the factors.

Genomic differentiation and selection signatures of two elite varieties of Yesso scallop Mizuhopecten yessoensis

Yesso scallop, Mizuhopecten yessoensis, is one of the most important bivalve species in aquaculture industry. Two selective improved varieties (Haida golden scallop and Zhangzidaohong) have been developed by artificial selection in recent years and exhibit good performance on growth and production traits. However, there's still a lack of comprehensive studies to analyze the population differentiation, genomic linkage disequilibrium patterns, as well as the selection signatures of the two elite varieties of Yesso scallop. In the present study, we performed whole genome resequencing of three groups of Yesso scallop to characterize the genetic changes resulted from selective breeding. A total of 9,534,749 high quality single nucleotide polymorphisms (SNPs) were discovered. The two selective varieties exhibited lower genetic diversity and retained relatively large linkage disequilibrium (LD) blocks compared to the reference population. Despite obvious stratification of the population structure of Yesso scallop, medium degrees of genetic differentiation (Fst < 0.15) was detected among the new varieties and the reference population. We highlighted several genes including LPCAT1 and TRAF reveal signatures of artificial selection and these genes would be potentially important for specific characteristics and improved performance in growth and resistance to diseases. The data and findings generated in our project would provide useful additions to currently available genomic resources for scallops and facilitate further genetic improvement and molecular studies in M.yessoensis.

Dynamics of stock for yesso scallop &lt;i&gt;Mizuhopecten yessoensis&lt;/i&gt; (Jay, 1856) in the northwestern Tatar Strait from the beginning of its fishery to nowadays

Settlements of yesso scallop Mizuhopecten yessoensis in the northwestern Tatar Strait (within the waters of Khabarovsk Region) are considered on the data of scuba (&lt; 20 m depth) and dredge (&gt; 20 m depth) surveys conducted in 2001–2018. To 2018, only two settlements remain in this area from 9–12 ones in 2010–2014; both remained settlements have no commercial value. Trend to decreasing of the settlements density is shown: the mean density was 3.0 ind./m2 in 2001, 0.20 ind./m2 in 2010, and 0.0005 ind./m2 in 2018. Commercially valuable scallops with the shell height &gt; 120 mm prevailed in the settlements (86–100 %), whereas juveniles were rare or absent (1.6 %, on average) in all years of surveys. CPUE decreased from 200 kg/diver/hour in 2001–2003 to 10 kg/diver/hour in 2018. These changes are obviously reasoned by overexploitation of the population using dredging and scuba gathering. Total commercial stock of yesso scallop dropped to the minimal value in 2018: 200 t, that was in 4.5 times lower than the established limit. Thus, 5 years ban is established for M. yessoensis landing in the area.

The role of the cadmium-binding protein response of the digestive gland of the Yesso scallop Mizuhopecten yessoensis (Jay, 1857) for marine environmental assessments

The ability of Pectinidae to accumulate heavy metals and store them in their tissues allows the use of scallops for biomonitoring marine pollution. High molecular weight metallothionein (MT)-like proteins (MTlps) play a central role in this process. Two major MTlps (72 and 43 kDa) have been identified in the digestive glands of Mizuhopecten yessoensis (Yesso scallop). These proteins have a very high affinity for the heavy metals cadmium, cobalt, and caesium. Additionally, these proteins can be deposited in large quantities in the digestive glands of this mollusc. It has been shown that 72 kDa MTlp is the main stress-response protein in areas polluted with cadmium or radioactive metals. Monitoring the amounts of MTlps in the digestive glands of the scallop M. yessoensis in areas with different anthropogenic pollutants has shown that these proteins are reliable biological markers of heavy-metal pollution in the marine environment.

Seasonal composition of immature germ cells in the Yesso scallop identified by vasa-like gene (my-vlg) and protein expression, with evidence of irregular germ cell differentiation accompanied with a high mortality event

The objective of this study was to understand germ cell renewal and differentiation in the Yesso scallop Mizuhopecten yessoensis throughout its reproductive cycle. First, we identified a Yesso scallop vasa-like gene (my-vlg) as a useful marker for immature germ cells. Both in situ hybridization and immunohistochemistry confirmed the germ-cell-specific expression of my-vlg and protein, especially in spermatogonia, oogonia, and primary oocytes. An immunohistochemistry with anti my-Vasa antibody further revealed that immature germ cells (i.e., gonial cells) are located on the basal membrane of germinal acini and are present during all maturational stages in both the ovary and testis. Quantitative analysis revealed a shift in germ cell number and change in germ cell composition associated with the gonadal maturation process, indicating a persistence of my-Vasa-positive immature germ cells throughout the reproductive cycle. In the testis, a gradual increase in my-Vasa-positive immature germ cells was seen from November to March. In the ovary, an increase in my-Vasa-positive immature germ cells was observed from September until November. We also used gonad index (GI) to summarize and evaluate the maturational changes of scallops in the 2018 generation. This generation had a background of relatively high mortality and shell deformity in the previous year, and we noted a small irregular peak of GI in the summer (July–August). We confirmed that the germ cells proliferating in the summer were my-Vasa-positive, implying that germ cell developmental progression occurred in the 2018 generation during the non-reproductive period. In conclusion, this study establishes an immuno-identification method for my-Vasa-positive immature germ cells and reveals germ cell composition in a bivalve species throughout its reproductive cycle. These results will support monitoring techniques for gonad development and the reproductive status of brood stock in shellfish seed production hatcheries.

Age-related changes in the anti-radical defense system in the tissues of Yesso scallop Mizuhopecten Yessoensis (JAY1857)

The glutathione level and the total oxyradical scavenging capacity in the digestive gland and the gills of the Yesso scallop Mizuhopecten yessoensis individuals of different ages (2-7 years) have been studied. The research revealed the tissue-specific high glutathione content in the gills of the scallop and the age-related decline tendency of glutathione level in the digestive gland. TOSC as a complex antioxidant capacity indicator is less tissue-specific but also depends on age.

Somatic and Reproductive Growth of the Yesso Scallop in Polluted Amur Bay

To elucidate the reproductive activity of the Yesso scallop Mizuhopecten yessoensis (Jay, 1857) in polluted Amur Bay (Peter the Great Bay, Sea of Japan), the seasonal patterns of growth of its gonad, adductor muscle, and digestive gland were studied. As the results of this study have shown, spawning in this polluted bay leads to a decrease in the weight of not only the gonads, but also the adductor muscle, and the digestive gland of scallops, which suggests that the energy spent for gametogenesis is provided, in particular, by the energy reserves of these somatic tissues. It has been found that in the years of heavy pollution of these waters, the decrease in the weight of the organs of the scallop for first gametogenesis was insignificant during the spawning period, which indicates the incomplete contribution of first-time spawning two-year-old individuals to reproduction of the population. With a decrease in the level of environmental pollution, two-year-old scallops show a significant loss in the weight of their gonad and somatic tissue during spawning; i.e., they undergo successful spawning. In the period of sexual maturity, the annual increment of somatic tissues decreases with age, but the reproductive activity increases, subsequently decreasing in the senile stage of the life history of the scallop.

FIRST EXPERIENCE OF CAGE CULTIVATION OF HATCHERY-PRODUCED JUVENILE SCALLOP MIZUHOPECTEN YESSOENSIS AT EASTERN COAST OF PRIMORYE

Yesso scallop Mizuhopecten yessoensis is the main object of aquaculture in Primorye with annual yield measured in hundreds ton. However, further development of its farming could be restricted by lack of the spat. Availability of the spat imported from China using for the scallop cultivation at the coast of Primorye is explored. The spat from Chinese hatchery located in Shandong province was supplied for one aquaculture company in Primorye in the volume of 660 . 106 ind. in 2018 and settled to hanging collectors (1000 ind. per bag), then to cages in the marine farm located north-eastward from the Moryak-Rybolov Bay. Survival and growth rate of the scallop juveniles were examined in early November 2018, when the water temperature was from 10.3–10.4 оС at the sea surface to 9.7–9.9 оС at the bottom, salinity was about 33.60 psu in the whole water column, chlorophyll a concentration varied in the range 0.4–0.8 mg/L with the maximum in the layer 8–24 m. The spat mortality during transportation was estimated as 15 %, but it increased to 56–90 % during its growing up in cages. This level of mortality is much higher than mortality of the spat collected from the coastal waters at southern Primorye. The highest mortality of artificial spat was observed for large-sized mollusks, whereas it was satisfactory for the small-sized ones. Possible reason of high mortality is too high density of juveniles and damaging of their soft tissues by other shells. The spat shells height did not exceed 5–10 mm in the collectors but increased during their growing in cages to 20–25 mm. This size is similar to the size of scallop growing from natural spat in southern Primorye. However, growth rate of the scallop growing at the Moryak-Rybolov Bay (2.0–2.7 mm/month) is lower than in Peter the Great Bay (3.0–3.5 mm/month) though higher than in the Vladimir Bay and Aniva Bay. Mean body weight of the cultivated scallop in November was 1.5 ± 0.1 g.

Functional characterization of an invertebrate gonadotropin-releasing hormone receptor in the Yesso scallop Mizuhopecten yessoensis

The neuropeptide control of bivalve reproduction with particular reference to gonadotropin-releasing hormone (invGnRH) is a frontier yet to be investigated. Bivalves are unique because they have two forms of the invGnRH peptide; however, there has been no functional characterization of the peptide–receptor pair. Therefore, the identification of a cognate receptor is a preliminary step toward exploring the biological roles of invGnRHs in bivalves. In this study, we functionally characterize an invGnRH receptor (invGnRHR) of a bivalve, the Yesso scallop Mizuhopecten yessoensis. In the receptor assay, HEK293 cells were transfected to transiently express the M. yessoensis invGnRHR (my-invGnRHR), which was found to be localized on the plasma membrane, confirming that my-invGnRHR, similar to other G-protein-coupled receptors, functions as a membrane receptor. Using both forms of invGnRH as ligands in a function-receptor assay, my-invGnRH11aa-NH2 stimulated intracellular Ca2+ mobilization but not cyclic AMP production, whereas my-invGnRH12aa-OH did not induce increase in Ca2+ levels. Therefore, we concluded that my-invGnRHR is an endogenous receptor specific to my-invGnRH11aa-NH2 which is hypothesized to be the mature peptide. To the best of our knowledge, this is the first study reporting the functional characterization of a bivalve invGnRHR.

Phenotypic Stability of Sex and Expression of Sex Identification Markers in the Adult Yesso Scallop Mizuhopecten yessoensis throughout the Reproductive Cycle

Simple SummaryBivalve sex is thought to fluctuate depending on environmental conditions. So far, there has been no investigation on the phenotypic stability of sex in the commercially important Yesso scallop Mizuhopecten yessoensis. The present study revealed that the sex of the Yesso scallop is stable after initial sex differentiation and that this species maintains a sex-stable maturation system throughout its life. In addition, gonad differentiation for each sex was precisely characterized by using molecular markers throughout the maturational cycle.The objective of the present study was to analyze the phenotypic stability of sex after sex differentiation in the Yesso scallop, which is a gonochoristic species that has been described as protandrous. So far, no study has investigated in detail the sexual fate of the scallop after completion of sex differentiation, although bivalve species often show annual sex change. In the present study, we performed a tracking experiment to analyze the phenotypic stability of sex in scallops between one and two years of age. We also conducted molecular marker analyses to describe sex differentiation and gonad development. The results of the tracking experiment revealed that all scallops maintained their initial sex phenotype, as identified in the last reproductive period. Using molecular analyses, we characterized my-dmrt2 and my-foxl2 as sex identification markers for the testis and ovary, respectively. We conclude by proposing that the Yesso scallop is a sex-stable bivalve after its initial sex differentiation and that it maintains a sex-stable maturation system throughout its life. The sex-specific molecular markers identified in this study are useful tools to assess the reproductive status of the Yesso scallop.

Fungal assemblages associated with commercial bivalve species in coastal waters of the Sea of Japan, Russia

Abstract A mycological study of three major commercial bivalve species, Yesso scallop Mizuhopecten yessoensis, Pacific oyster Crassostrea gigas, and bay mussel Mytilus trossulus, from the coastal waters off Rikord Island (Peter the Great Bay, Sea of Japan) has been conducted. A total of 52 species of filamentous fungi from 19 genera of ascomycetes (and their anamorphic stages) and zygomycetes were isolated from shells and internal organs of the examined bivalves. Thirty-eight species (18 genera) of filamentous fungi were isolated from Yesso scallop, 21 species (eight genera) from Pacific oyster and 10 species (seven genera) from bay mussel. The studied bivalves showed a low degree of similarity in the diversity of the filamentous fungi. The identified filamentous fungi of the genera Aspergillus, Penicillium, Cladosporium, Chaetomium, etc. belong to a group of opportunistically pathogenic and toxigenic microorganisms that can cause mycoses and mycotoxicoses in aquatic animals.

Phosphorylation properties of twitchin from Yesso scallop catch and striated muscles

Molluscan smooth muscle exhibits a unique muscle contraction, called catch, where the tension is maintained for long periods with little energy consumption. Catch contraction is regulated by twitchin, also called mini-titin, a member of the titin/connectin family. Twitchin is also found in molluscan non-catch striated muscle. We isolated twitchins from catch and striated muscles in the Yesso scallop Mizuhopecten yessoensis. Both twitchins are ~500 kDa in size. Western blotting using the anti-twitchin kinase domain antibody revealed that both twitchins have a kinase domain. Both twitchins were phosphorylated by the catalytic subunit of cAMP-dependent protein kinase in vitro. Stoichiometric analysis revealed that 0.6 and 1.7 mol Pi were incorporated into catch and striated muscle twitchins, respectively. Phosphopeptide mapping revealed that catch muscle twitchin has one phosphorylation site, whereas striated muscle twitchin has two. cDNA cloning gave partial sequences of two Yesso scallop twitchin isoforms. One had two putative phosphorylation sites and the other had one.

Molecular characterization of calponin in the catch muscle of the Yesso scallop Mizuhopecten yessoensis

Full-length cDNA clone encoding calponin from the catch muscle of the Yesso scallop, Mizuhopecten yessoensis, was isolated and sequenced. Scallop calponin consists of 384 amino acid residues and its deduced molecular weight was 42,154. The motif structure is composed of a single calponin homology domain and five tandem calponin domains, which are repeats of a 25 amino acid sequence. Sixty-four percent (64 %) of the amino acids identified in Yesso scallop calponin were similar to that from the anterior byssus retractor muscle (catch muscle) of the mussel Mytilus galloprovincialis. Dot blot and reverse transcription polymerase chain reaction (RT-PCR) analyses revealed that Yesso scallop calponin is mainly expressed in the catch muscle and, to a lesser extent, the mantle. Western blot analysis performed using rabbit anti-Yesso scallop calponin antiserum raised the possibility that a calponin isoform with a larger molecular weight is expressed in striated muscle.

Filamentous fungi in the epibiosis of the scallop Mizuhopecten yessoensis (Bivalvia) in Peter the Great Bay, Sea of Japan

This study considers the taxonomic composition of filamentous fungi in the epibiosis on the shell of the Yesso scallop Mizuhopecten yessoensis (Jay, 1856) (Bivalvia), which were collected in open waters of Peter the Great Bay, Sea of Japan. The taxonomic composition was found to include ten species of filamentous fungi, nine of which were identified. The revealed species belong to six genera, viz., Aspergillus, Aphanocladium, Cladosporium, Penicillium, Phialophorophoma, and Eurotium.

Thermostability of striated and smooth adductor muscle tropomyosins from Yesso scallop Mizuhopecten yessoensis

The striated and smooth adductor muscle tropomyosins (TMs) of Yesso scallop Mizuhopecten yessoensis have been known to express different isoforms, but have not been characterized in detail to date. In the present study, TMs from both muscles of Yesso scallop were purified and their stabilities were compared by circular dichroism (CD) spectrometry and differential scanning calorimetry (DSC). From the CD data, the apparent melting temperature and the apparent free energy of folding at 20 degrees C were calculated to be 30.5 degrees C and -13.4 kJ/mol, and 36.0 degrees C and -31.9 kJ/mol for the striated and smooth muscle TMs, respectively. From the DSC data, DeltaH values were calculated to be 1.87 x 10(3) and 2.19 x 10(3) kJ/mol for striated and smooth muscle TMs. These results suggest that smooth muscle TM has higher thermostability than striated muscle TM. The amino acid residues responsible for such stability difference were considered to be the six amino acid substitutions in the middle region of the TM molecules.