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Seafood is one of the most important sources of nutrients. However, they have a short shelf-life and the traditional preservation methods may generate losses in their natural flavour and nutrients. Thisstudy evaluated and optimize the High Pressure Processing (HPP) regarding pressure level (200--400 MPa) and holding time (0--5 min) applied to lion's paw scallop (Nodipecten nodosus) to reduce microbial contamination while maintaining desirable characteristics. Response surface methodology with a Box-Behnken design and Desirability function were employed to simultaneously optimize these quality attributes. HPP enhanced microbial quality at 200 MPa/5 min, despite promoting inadequate physical-chemical modifications in the adductor muscle of the scallop. In such processing condition, in spite of a slight increase in muscle humidity which could be of benefit, pH increase was also verified, as well as a decrease in water holding capacity (WHC). At more severe level (400 MPa/5 min), a decrease in the shear force related to instrumental texture and in Whiteness (W) and Luminosity (L*) related to color was observed. Simultaneous optimization provided a value of 365MPa / 2min where physicochemical characteristics would be the more similar to the scallop without facing a preservation process. [ABSTRACT FROM AUTHOR]

Over the past decades, valvometric techniques have been commonly used to record valve opening activities of bivalves. Various relationships with environmental variations have been elucidated through different types of metrics extracted from valvometric signals (e.g. valve opening, cyclicity, specific behaviours). Although automated data processing methods exist, many specific behaviours are still annotated manually. This study proposes an algorithm to detect and classify the behaviours performed by the great scallop (Pecten maximus) in two categories: jump-like (JL) behaviours and other behaviours (OBs). These two categories differ in the shape of their valvometric signal, JL being movements of high amplitudes associated with 'displacement movements' (rotation, swimming, jumping, flipping) and OB grouping all other movements of lower amplitudes ('common movements'), such as partial closures, which are produced routinely. This algorithm has been developed and tested on 10 scallop valve opening time series recorded using fully autonomous valvometers based on the Hall effect principle. The algorithm detected 93.65% ± 5.5 of manually annotated behaviours produced by scallops, with a false detection rate of less than 6.3% ± 5.5. Classification performances vary according to the type of behaviour. JL behaviours and OBs were well classified at 83.72% ± 23.09 and 98.92% ± 1.80, respectively. Analysis of the algorithm's outputs, highlighting potential daily trends in the production of certain behaviours, shows their relevance for acquiring information on the biology of scallops. By providing an efficient and flexible detection and classification method, this study is a first step towards the automation of bivalve behaviour detection. This study also highlights the importance of simultaneously using Hall sensors and accelerometers to accurately classify the complex behaviours of mobile bivalves such as P. maximus. [ABSTRACT FROM AUTHOR]

As an innovative type of damper seal, the scallop damper seal (SDS) has shown greatly improved sealing performance for the high-compactness supercritical CO2 (S-CO2) turbomachinery, but leakage-induced excitation forces have an impact on the rotor stability. In this research, we improve the rotordynamic solution based on the multi-frequency elliptic whirling model for the S-CO2 seals and investigate the leakage-induced excitation behavior of SDS depending on seal geometry and operating condition. By comparing the results of a labyrinth seal and a full-partition pocket damper seal, we prove that SDS has better rotordynamic performance for the S-CO2 compressor. The results show that increasing the pressure drop favors greater direct stiffness and effective damping of the SDS. Inlet preswirl changes the direction of fluid-response force to coincide with the rotor motion, which is detrimental to rotor stability. Changing the cavity depth has no significant effect on the dynamic characteristics of the SDS, but shortening the cavity length reduces the direct stiffness to below zero. Supplementing the number of circumferential cavities increases the direct stiffness and effective damping but results in SDS not being able to be machined directly by milling cutters. The design with 12 circumferential cavities is recommended for the 100-kW-class S-CO2 compressor. [ABSTRACT FROM AUTHOR]

Background: Transforming growth factor β (TGF-β) superfamily genes can regulate various processes, especially in embryogenesis, adult development, and homeostasis. To understand the evolution and divergence patterns of the TGF-β superfamily in scallops, genome-wide data from the Bay scallop (Argopecten irradians), the Zhikong scallop (Chlamys farreri) and the Yesso scallop (Mizuhopecten yessoensis) were systematically analysed using bioinformatics methods. Results: Twelve members of the TGF-β superfamily were identified for each scallop. The phylogenetic tree showed that these genes were grouped into 11 clusters, including BMPs, ADMP, NODAL, GDF, activin/inhibin and AMH. The number of exons and the conserved motif showed some differences between different clusters, while genes in the same cluster exhibited high similarity. Selective pressure analysis revealed that the TGF-β superfamily in scallops was evolutionarily conserved. The spatiotemporal expression profiles suggested that different TGF-β members have distinct functions. Several BMP-like and NODAL-like genes were highly expressed in early developmental stages, patterning the embryonic body plan. GDF8/11-like genes showed high expression in striated muscle and smooth muscle, suggesting that these genes may play a critical role in regulating muscle growth. Further analysis revealed a possible duplication of AMH, which played a key role in gonadal growth/maturation in scallops. In addition, this study found that several genes were involved in heat and hypoxia stress in scallops, providing new insights into the function of the TGF-β superfamily. Conclusion: Characteristics of the TGF-β superfamily in scallops were identified, including sequence structure, phylogenetic relationships, and selection pressure. The expression profiles of these genes in different tissues, at different developmental stages and under different stresses were investigated. Generally, the current study lays a foundation for further study of their pleiotropic biological functions in scallops. [ABSTRACT FROM AUTHOR]

Ba/Cashell, Mo/Cashell, and Li/Cashell chronologies of Pecten maximus can provide information on past phytoplankton dynamics. Distinct Ba, Mo, and Li peaks in the shells are associated with algal blooms. This study evaluated the underlying hypothesis that respective element profiles reliably record variations in phytoplankton dynamics occurring within the water column. Therefore, the chemical content of scallops from the Bay of Brest, France, that lived on the sediment surface was compared to conspecific specimens living in a cage above the seafloor and compared with the phytoplankton abundance and the physicochemical properties of the water column. As demonstrated, Ba/Cashell and Mo/Cashell peaks occurred contemporaneously in specimens within the cage and on the sediment, but were higher in the latter. Furthermore, element/Ca peaks agreed with the timing of particulate Ba and Mo enrichments in the seawater. These data support the assumption of a dietary uptake of both elements. Differences in peak heights between shells living in a cage and on the seafloor were controlled by rates of filtration and biomineralization. While the timing and magnitude of Ba/Cashell peaks were linked to Ba‐containing diatoms, Mo/Cashell peaks were related to blooms of Mo‐enriched dinoflagellate and diatom aggregation events. Two episodes of slight Li enrichment occurred synchronously in cage and sediment shells. Although the exact mechanism causing such Li increases remains unresolved, the findings suggest a link to large diatom blooms or the presence of a specific diatom taxon. This study refines previously hypothesized relationships between trace element enrichments in scallop shells and phytoplankton dynamics. [ABSTRACT FROM AUTHOR]

Owing to the constant wind generated by the vast ocean, energy production from offshore wind farms (OWFs) plays an important role in the expansion of renewable energy. However, areas close to large wind farms are often left unutilized, and aquaculture farmers find it difficult to efficiently utilize these unoccupied spaces due to limited information showing the feasibility of utilization of OWFs as potential scallop culture sites. To analyze whether the two scallop species Zhikong scallop (Chlamys farreri) and bay scallop (Argopecten irradians) can be grown at OWFs of Gochang and Buan, Jeollabuk-do, Republic of Korea, the growth characteristics of the two scallop species were analyzed and compared with those grown at the Tongyeong Megacosm Test Station. The results clearly showed that the growth of scallops at the OWF was significantly lower with respect to the shell lengths, height, width, and weight, compared to those grown at the megacosm station. However, scallops grown at the OWF still showed consistent growth in parallel with those grown at the megacosm test station. Yet, there was a species-specific mortality rate between the two sites. In addition, our results suggest that temperature may be a key determinant of the growth of C. farreri and A. irradians. Overall, this study contributes to establishing a foundation for the stable and continuous farming of marine bivalves (e.g., clams, oysters, mussels, and scallops) in OWF areas. [ABSTRACT FROM AUTHOR]

Different from the diverse family Pectinidae, the Spondylidae is a small group with a single genus that shares the sedentary life habit of cementing themselves to the substrate. However, little information related to the genetic diversity of Spondylidae has been reported. In the present study, the complete mitochondrial genomes of Spondylus versicolor and S. spinosus were sequenced and compared with those of pectinids. The mtDNA of S. versicolor and S. spinosus show similar patterns with respect to genome size, AT content, AT skew, GC skew, and codon usage, and their mitogenomic sizes are longer than most pectinid species. The mtDNA of S. spinosus is 27,566 bp in length, encoding 13 protein-coding genes, 22 transfer RNA genes, and 2 ribosomal RNA genes, while an additional tRNA-Met was found in the mtDNA of S. versicolor, which is 28,600 bp in length. The monophylies of Spondylidae and Pectinidae were well supported, but the internal relationships within Pectinidae remain unresolved due to the paraphyly of the genus Mimachlamy and the controversial position of the tribe Aequipectinini. The gene orders of S. versicolor and S. spinosus are almost identical but differ greatly from species of the Pectinidae, indicating extensive gene rearrangements compared with Pectinidae. Positive selection analysis revealed evidence of adaptive evolution in the branch of Spondylidae. The present study could provide important information with which to understand the evolutionary progress of the diverse and economically significant marine bivalve Pectinoidea. [ABSTRACT FROM AUTHOR]

Summary: Recently, food‐derived peptides were frequently studied and used as metal ion chelator against negative effects of trace element absorption induced by various human gastrointestinal environments. In this study, the scallop mantle hydrolysates (SMHs) were produced and characterised to study their intestinal promotion of zinc absorption. During production of hydrolysates, the results of degree of hydrolysis (DH) and proteins solubility suggested that the alcalase was suitable for the production of peptides from scallop mantle proteins where the chelating conditions were settled (30 °C, 10 min and 3 mg mL−1). The molecular distribution of SMH was mainly 1–5 kDa and chelation of zinc with SMH (involved in carboxyl and amine group of SMH) triggered no significant alteration on the secondary structure of SMH. Zinc morphologically altered the surface structures of SMH. Moreover, SMH could successfully carry and transport zinc while the fluorescence staining indicated free zinc accumulated inside the tissue of everted rat sacs. Finally, several representative transported peptides (intact or cleaved) were identified, such as FTGEPGPSGPT, AINDPFIDL and ALPHAILRI. This study provided a theoretical basis for the investigation of absorption of marine animal‐derived peptides as zinc carriers. [ABSTRACT FROM AUTHOR]

Valvometry techniques used to monitor bivalve gaping activity have elucidated numerous relationships with environmental fluctuations, along with biological rhythms ranging from sub-daily to seasonal. Thus, a precise understanding of the natural activity of bivalves (i.e., not exposed to stressful environmental variations) is necessary as a baseline for detecting abnormal behaviors (deviations). This knowledge is also needed to reliably interpret observations of bivalve gaping behavior and associated biological processes (e.g., respiration, nutrition) acquired over time-limited periods. With this in mind, we investigated the natural daily gaping activity of the great scallop (Pecten maximus) by continuously monitoring 35 individuals in several individual tanks and in situ (Bay of Saint-Brieuc, Brittany, France) using fully autonomous Hall effect sensors. Our results revealed a circadian cycle (τ = 24.0h) in scallop gaping activity. Despite significant inter-individual variability in mean opening and cycle amplitude, almost all individuals (87.5%) exhibited nocturnal activity, with valves more open at night than during the day. A shift in light regime in the tanks triggered an instantaneous change in opening pattern, indicating that light levels strongly determine scallop activity. Based on the opening status of scallops, we also identified several gaping behaviors deviating from the regular daily pattern (lack of rhythmicity, high daytime opening), potentially reflecting physiological weakness. While further long-term studies are required to fully understand the natural activity of scallops, these findings pave the way for studies focused on the scallop response to external factors and introduce further research into the detection of abnormal behaviors. Coupling observations of diel valve gaping cycles with other daily variations in organismal and environmental parameters could help explain mechanisms driving the growth patterns of scallops observed in their shell striations. From a technical perspective, our field-based monitoring demonstrates the suitability of autonomous valvometry sensors for studying mobile subtidal bivalve activity in remote offshore environments. [ABSTRACT FROM AUTHOR]

Aquaculture is the fastest growing food production sector in the world and is quickly diversifying. In the Northwest Atlantic, interest in sea scallop (Placopecten magellanicus) (hereafter scallop) aquaculture has grown substantially. However, technical and economic challenges have hindered industry growth. We conducted bioeconomic simulations for various sized farms that targeted either live "whole" scallops or the shucked adductor muscle "meat." The majority of farms selling whole scallops were profitable. However, all farms selling meats generated negative returns. Labor made up the greatest portion of costs in model simulations and increased linearly with farm size, representing a significant bottleneck. Whole scallop farm value was most sensitive to changes in (1) market price and (2) time to market. Our analysis suggests four strategies to increase farmed scallop production in the Northwest Atlantic: (1) mechanize low density net culture, (2) optimize net stocking densities, (3) build site selection tools, and (4) invest in consumer education, end-markets, and biotoxin testing for whole scallops. The sector will require a combination of regulatory, industry, and research cooperation to overcome these pressing challenges, but holds the potential to profitably diversify the bivalve aquaculture industry. [ABSTRACT FROM AUTHOR]

Despite the great importance of gills for bivalve mollusks (respiration, feeding, immunity), the microbiota associated with this tissue has barely been characterized in scallops. The scallop Argopecten purpuratus is an important economic resource that is cultivated in areas where coastal upwelling is intensifying by climate change, potentially affecting host-microbiota interactions. Thus, we first characterized the bacterial community present in gills from cultivated scallops (by 16S rRNA gene amplicon sequencing) and assessed their stability and functional potential in animals under farm and laboratory conditions. Results showed that under both conditions the gill bacterial community is dominated by the phylum Campylobacterota (57%), which displays a chemoautotrophic potential that could contribute to scallop nutrition. Within this phylum, two phylotypes, namely symbionts A and B, were the most abundant; being, respectively, taxonomically affiliated to symbionts with nutritional functions in mussel gills, and to uncultured bacteria present in coral mucus. Additionally, in situ hybridization and scanning electron microscopy analyses allowed us to detect these symbionts in the gills of A. purpuratus. Given that shifts in upwelling phenology can cause disturbances to ecosystems, affecting bacteria that provide beneficial functions to the host, we further assessed the changes in the abundance of the two symbionts (via qPCR) in response to a simulated upwelling intensification. The exposure to combined decreasing values in the temperature, pH, and oxygen levels (upwelling conditions) favored the dominance of symbiont B over symbiont A; suggesting that symbiont abundances are modulated by these environmental changes. Overall, results showed that changes in the main Campylobacterota phylotypes in response to upwelling intensification could affect its symbiotic function in A. purpuratus under future climate change scenarios. These results provide the first insight into understanding how scallop gill-microbial systems adapt and respond to climate change stressors, which could be critical for managing health, nutrition, and scallop aquaculture productivity. [ABSTRACT FROM AUTHOR]

Nutrient restriction (NR) extends lifespan in many species. High latitudes are characterized by cold-water temperature and food limitations, where bivalves may mimic NR like vertebrates, which could result in a prolonged life expectancy. The long-lived Peruvian scallop (7–10 years) distributes naturally at relatively higher latitudes than the annual bay scallop. However, the relationship and the mechanism underlying the food availability and lifespan are unclear in bivalves. In this study, the genetic response to NR was first investigated in bivalves with distinct lifespans. Peruvian scallops persistently responded to NR mainly via metabolic pathways, but that began to play roles in bay scallops after 56 days. Significant down-regulated expression of long-chain saturated fatty acid synthetase in both two scallops and increased expression of SCD5 and LIPN2 in Peruvian scallops might contribute to MUFA accumulation under NR. SOD1 was more highly expressed in Peruvian scallops than in bay scallops under NR, and strong autophagy was detected only in Peruvian scallops. Peruvian scallops presented much lower MDA levels and higher SOD1 activities than bay scallops. These findings help us understanding the role of lipases and antioxidases in longevity of bivalves, and provide potential biomarkers for breeding long-lived larger scallops. [ABSTRACT FROM AUTHOR]

The effect of different antioxidants of bamboo leaves (AOB) treatment on lipid oxidation of scallop (Argopecten irradians) adductor muscle during hot air drying was investigated. The results demonstrated that the marinated sample had the lowest peroxide value, thiobarbituric acid-reactive substances, polyunsaturated fatty acids loss, free radical level, and lipoxygenase activity during drying, indicating that the marination process maximized the antioxidant effects of AOB. The results indicate that this process could interfere with free radical chain reaction and inhibit lipoxygenase activity since AOB is correctly distributed on the site of lipid oxidation. After drying, eicosapentaenoic acid + docosahexaenoic acid content in control, unmarinated, and marinated samples decreased by 26.10%, 11.25%, and 7.29%, respectively, suggesting that the marination process maintained more efficiently its high nutritive value in terms of lipid content. Overall, the use of AOB provides a more effective strategy to control lipid oxidation in seafood, mainly scallops, during drying. [ABSTRACT FROM AUTHOR]

Large-scale offshore wind farms are a critical component of the worldwide climate strategy. However, their developments have been opposed by the fishing industry because of concerns regarding the impacts of pile driving vibrations during constructions on commercially important marine invertebrates, including bivalves. Using field-based daily exposure, we showed that pile driving induced repeated valve closures in different scallop life stages, with particularly stronger effects for juveniles. Scallops showed no acclimatization to repetitive pile driving across and within days, yet quickly returned to their initial behavioral baselines after vibration-cessation. While vibration sensitivity was consistent, daily pile driving did not disrupt scallop circadian rhythm, but suggests serious impacts at night when valve openings are greater. Overall, our results show distance and temporal patterns can support future mitigation strategies but also highlight concerns regarding the larger impact ranges of impending widespread offshore wind farm constructions on scallop populations. [ABSTRACT FROM AUTHOR]

This work aimed to assess the occurrence of compensatory growth in Nodipecten nodosus farmed in Caraguatatuba, Brazil, during intermediate phase at the densities of 50 (control), 800, 1600 and 3200 m−2. Subsequently the densities were reduced to 50 m−2 for the growout phase, in which each treatment consisted of scallops originating from the same density used during the intermediate phase, with mean height equal to the average recorded in each density. The treatments were named according to the original density (T50, T800, T1600 and T3200). At the end of the intermediate phase, height, survival and specific growth rate (SGR) were significantly higher for the density of 50 m−2. After the growout phase, height was higher in T50, but the total SGR and increase in height were lower. Survivals, adductor muscle dry weight, total dry weight and condition index did not differ significantly. In addition, during the intermediate phase, SGR was higher in scallops at 50 m−2, but, at the beginning of the growout phase, SGR decreased in T50 scallops and increased in those of the other treatments. The results indicated the occurrence of compensatory growth in N. nodosus, which would allow increasing stocking densities in the intermediate phase. [ABSTRACT FROM AUTHOR]

Phosphatase and tensin homolog deleted on chromosome ten (PTEN) has been found to regulate longevity through the PI3K/Akt/FoxO pathway and maintenance of genome integrity in worms, flies, and mammals. However, limited information is available on the roles of PTEN in longevity of aquatic animals. Here we extended this paradigm using two closely related Argopecten scallops, Argopecten purpuratus, and Argopecten irradians, with significantly distinct life spans, which are commercially important bivalve species for fishery and aquaculture in China, United States, Peru, and Chile. The ORFs of the ApPTEN and AiPTEN were 1,476 and 1,473 bp, which encoded 491 and 490 amino acids, respectively. There were 48 synonymous and 16 non-synonymous SNPs and one InDel of three nucleotides between ApPTEN and AiPTEN, resulting in variations in 15 amino acids and lack of S453 in AiPTEN. Differences in conformation and posttranslational modification were predicted between ApPTEN and AiPTEN, which may indicate different activities of ApPTEN and AiPTEN. When the animals were subjected to nutrition restriction, the expression of both ApPTEN and AiPTEN was upregulated, with AiPTEN responded faster and more robust than ApPTEN. Ionizing radiation induced significantly elevated expression of ApPTNE but not AiPTEN in the adductor muscle, and the mortality rate of A. purpuratus was significantly lower than that of A. irradians, indicating that ApPTNE may play a protective role by maintaining the genome integrity. RNAi of ApPTNE significantly downregulated the expression of its downstream regulated genes known to favor longevity, such as FoxO, Mn-SOD, and CAT. These results indicated that PTEN may contribute to the longevity of A. purpuratus through regulation of nutrient availability and genomic stability, probably via PI3K/Akt/FoxO pathway. Our study may provide new evidence for understanding of the conservative functions of PTEN in regulation of lifespan in animals and human, and it may also benefit the selection of scallops strains with long lifespan and thus larger size. [ABSTRACT FROM AUTHOR]

Eyes are remarkable systems to investigate the complex interaction between ecological drivers and phenotypic outcomes. Some animals, such as scallops, have many eyes for visual perception, but to date, the evolution of multiple‐eye systems remains obscure. For instance, it is unclear whether eye number changes over a lifetime or varies among species. Scallops are a suitable model group to investigate these questions considering the interspecific variation of adult size and ecological diversity. We tested whether eye abundance scales with body size among individuals and species and whether it varies with life habits. We performed comparative analyses, including a phylogenetic ANCOVA and evolutionary model comparisons, based on eye count and shell height (as a proxy of body size) across 31 scallop species. Our analyses reveal that patterns of increasing relationship with body size are not concordant among taxa and suggest ontogenetic convergence caused by similar ecologies. Accordingly, selective optima in eye numbers are associated with shifts in life habits. For instance, species with increased mobility have significantly more eyes than less mobile species. The convergent evolution of greater eye abundance in more mobile scallops likely indicates a visual improvement based on increased levels of oversampling of the surrounding environment. [ABSTRACT FROM AUTHOR]

Argopecten scallops are hermaphroditic bivalves and commercially important in aquaculture. Up to now, the molecular mechanism of sex differentiation and gonad growth/maturation in hermaphroditic animals is still largely unknown. In this study, we analyzed the transcriptome of the gonads at different stages of the QN Orange scallop, a new scallop strain selected from the hybrids between the bay scallop and the Peruvian scallop. Among sex differentiation‐related genes, 5 transcription factors (TFs) (1 SOX, 2 FOXL and 2 GATA) and 2 TGF‐βs (2 BMP) were mainly expressed in the male part and 2 TFs (1 FOXL and 1GATA) and 2 TGF‐βs (2 BMP) were mainly expressed in the female part of the gonads. Among gonad growth/maturation related genes, 1 TF (GATA) might be only involved in male gonad growth/maturation, 8 TFs (1 SOX, 1 WNT, 2 FOXL and 4 GATA) and 3 TGF‐βs (1 GDF and 2 BMP) only participated in ovarian growth/maturation, 3TFs (1 SOX, 1 DMRT and 1 FOXL) and 2 TGF‐βs (1 GDF and 1 BMP) might be involved in both male and female gonad growth/maturation. Based on the results of transcriptome and qRT‐PCR, 11 genes were screened to be involved in sex differentiation and 16 genes might be involved in gonad growth/maturation. The results of this study may provide new insights into the understanding of the mechanisms of sex differentiation and gonad growth/maturation in hermaphroditic scallops. [ABSTRACT FROM AUTHOR]

This study investigated the effects of different tea polyphenol (TP) treatments (control, unmarinated, and marinated) on scallop adductor muscle lipid oxidation during hot air drying. Results showed that the marinated sample had the lowest peroxide value, thiobarbituric acid reactive substances, polyunsaturated fatty acids loss, free radical level, and lipoxygenase activity during drying, indicating that the marination process maximized the antioxidant effects of TP. These results were achieved by the distributing of TP on lipid oxidation site, effectively intercepting free radical chain reaction and inhibiting lipoxygenase activity. The significant loss of total phenolic content in the marinated sample confirmed this result. The control, unmarinated, and marinated sample lost 26.52%, 9.99%, and 6.46% of eicosapentaenoic acid and docosahexaenoic acid during drying, respectively, indicating that the marination more efficiently maintained its high nutritive value in terms of lipid. This study provided a more effective way of using TP to control lipid oxidation in seafood during drying. Novelty impact statement: Marinated with TP improved its antioxidant effect during scallop drying.More than 26% of EPA + DHA lost in scallop adductor muscle, while less than 7% of EPA + DHA lost in marinated scallop adductor muscle during drying.Marinated with TP maintained the higher nutritive value of scallop during drying. [ABSTRACT FROM AUTHOR]

Marine molluscs constitute the second largest marine fishery and are often caught in coastal and estuarine habitats. Temperature is increasing in these habitats at a rate greater than predicted, especially in warming "hotspots". This warming is accompanied by hypoxia in a duo of stressors that threatens coastal mollusc fisheries and aquaculture. Collapses of the northern bay scallop (Argopecten irradians irradians) fisheries on the Atlantic coast of the USA are likely to be driven by rapid rates of coastal warming and may provide an ominous glimpse into the prospects of other coastal mollusc fisheries in climate warming hotspots. [ABSTRACT FROM AUTHOR]

The first filial (F 1) generation from the successful hybridization of bay scallops (Argopecten irradians) and Peruvian scallops (A. purpuratus) exhibits significant heterosis, playing a crucial role in enhancing the germplasm and increasing yields of the scallops. However, there is significant variation in the growth traits of the F 1 hybrid population, and there is little information concerning its hereditary basis. To unravel the heterosis mechanism and identify key loci and genes contributing to superhybrids, genome-wide association study (GWAS) with additive and epistasis models were conducted for six growth-related traits in the F 1 hybrid scallop population in this study. In total, 18,789,547 single nucleotide polymorphisms (SNPs) were identified after filtering from 198 hybrid individuals, comprising 63.5% of maternal loci and 36.5% of paternal loci. The additive model revealed 2768 associated SNPs and 14 candidate genes, with most of the loci associated with the body mass traits. The additive-additive epistatic model identified 133,094 SNP interaction pairs and 20 candidate gene pairs with exon region SNPs, which were predominantly associated with shell morphology traits. Almost all the SNP pairs associated with body mass traits were maternal-maternal interactions, but the shell morphology traits had the most maternal-paternal and maternal-maternal interactions, suggesting that body mass traits might be affected mainly by maternal effects and that parental interaction effects mainly contributed to the shell size of the hybrid scallops. Both in the shell morphology and the body mass traits, multiple loci participate in epistasis, interacting with more than one locus and forming high-order epistatic interactions, which could be critical factors contributing to the heterosis observed in hybrid scallops. The identified associated loci and candidate genes not only constitute valuable resources for the molecular breeding of hybrid scallops, contributing to the improvement of growth-related traits, but also revealed mechanisms underlying heterosis in aquatic species, providing insights into the advantages of heterosis and paving the way for future research on hybridization in aquatic organisms. • A genome-wide association analysis on six growth traits of hybrid scallops. • The haplotyped maternal and paternal genomes used for genotyping. • Dramatically more epistatic-effect SNP pairs than additive-effect SNPs. • Different genetic effects impact distinct growth traits in hybrid scallops. [ABSTRACT FROM AUTHOR]

Myeloid differentiation factor-88 (MyD88) is a key adaptor of the toll-like receptor (TLR) signaling pathway and plays a crucial role in innate immune signal transduction in animals. However, the MyD88-mediated signal transduction mechanism in shellfish has not been well studied. In this study, a new MyD88 gene, CfMyD88-2 , was identified in the Zhikong scallop, Chlamys farreri. The 1779 bp long open reading frame encodes 592 amino acids. The N-terminus of Cf MyD88-2 contains a conserved death domain (DD), followed by a TIR (TLR/Interleukin-1 Receptor) domain. The results of the multi-sequence comparison showed that the TIR domain sequences were highly conserved. Phylogenetic analysis revealed that Cf MyD88-2 was first associated with Mizuhopecten yessoensis MyD88-4 and Argopecten irradians MyD88-4. CfMyD88-2 mRNA was expressed in all scallop tissues, as detected by qRT-PCR, and the expression level was the highest in the mantle and hepatopancreas. In addition, CfMyD88-2 mRNA expression significantly increased after pathogen-associated molecular patterns (PAMPs, such as lipopolysaccharide, peptidoglycan, or polyinosinic-polycytidylic acid) stimulation. The results of the co-immunoprecipitation experiments in HEK293T cells showed that both CfMyD88-1 and CfMyD88-2 interacted with the TLR protein of scallops, suggesting the existence of more than one functional TLR-MyD88 signaling axis in scallops. Dual luciferase reporter gene assays indicated that the overexpressed Cf MyD88-2 in HEK293T cells activated interferon (IFN) α , IFN-β , IFN-γ , and NF-κB reporter genes, indicating that the protein has multiple functions. The results of the subcellular localization experiment uncovered that Cf MyD88-2 was mainly localized in the cytoplasm of human cells. In summary, the novel identified Cf MyD88-2 can respond to the challenge of PAMPs, participate in TLR immune signaling, and may activate downstream effector genes such as NF-κB gene. These research results will be useful in advancing the theory of innate immunity in invertebrates and provide a reference for the selection of disease-resistant scallops in the future. • The second MyD88 gene (CfMyD88-2) were identified in the Zhikong scallop. • CfMyD88-2 expression was induced by LPS, PGN and poly(I:C) challenge. • Cf MyD88-1 and Cf MyD88-2 interact with scallop TLR in HEK293T cells. • Overexpressed Cf MyD88-2 in HEK293T cells activated IFNα/β/γ and NF-κB reporter genes. [ABSTRACT FROM AUTHOR]

Myofibrillar protein (MP) is susceptible to the effect of ionic strength and ultra-high pressure (UHP) treatment, respectively. However, the impact of UHP combined with ionic strength on the structure and in vitro digestibility of MP from scallop mantle (Patinopecten yessoensis) is not yet clear. Therefore, it is particularly important to analyze the structural properties and enhance the in vitro digestibility of MP by NaCl and UHP treatment. The findings demonstrated that as ionic strength increased, the α-helix and β-sheet gradually transformed into β-turn and random coil. The decrease of endogenous fluorescence intensity indicated the formation of a more stable tertiary structure. Additionally, the exposure of internal sulfhydryl groups increased the amount of total sulfhydryl content, and reactive sulfhydryl groups gradually transformed into disulfide bonds. Moreover, it reduces aggregation through increased solubility, decreased turbidity, particle sizes, and a relatively dense and uniform microstructure. When MP from the scallop mantle was treated with 0.5 mol/L ionic strength and 200 MPa UHP treatment, it had the highest solubility (90.75 ± 0.13%) and the lowest turbidity (0.41 ± 0.03). The scallop mantle MP with NaCl of 0.3 mol/L and UHP treatment had optimal in vitro digestibility (95.14 ± 2.01%). The findings may offer a fresh perspectives for developing functional foods for patients with dyspepsia and a theoretical foundation for the comprehensive utilization of scallop mantle by-products with low concentrations of NaCl. [Display omitted] • At 0.3 mol/L NaCl concentration, MP solution was uniform and stable. • NaCl addition (0.3 mol/L) assisted UHP (200 MPa) improved the in vitro digestibility of MP. • UHP is a good method to improve the MP digestibility by reducing salt addition. [ABSTRACT FROM AUTHOR]

Quantifying predator–prey interactions and gaining insights into predator behavior are crucial for optimizing restoration strategies. However, such knowledge is often lacking for marine invertebrates. We examined potential impacts of predation by channeled Busycotypus canaliculatus and knobbed whelks Busycon carica on natural and planted populations of bay scallops in the Peconic Bays, New York, through laboratory and field investigations. In lab experiments, mean predation rates exhibited by small channeled whelks were low: 0.06 and 0.005 scallops d−1 for adult and juvenile scallops, respectively. Predation rates of small knobbed whelks on juvenile scallops were 22 × higher. Eighty-six percent (86%) of scallops consumed by channeled whelks had undamaged shells, while 73% eaten by knobbed whelks had notched ventral margins. In field plots where scallop densities were manipulated via removals/plantings, whelks consumed ~ 2% of ~ 19,100 planted juveniles, whereas crabs and presumably finfish consumed > 40% overall. Acoustic telemetry revealed that tagged channeled whelks moved shorter distances and spent more time in plots planted with scallops versus those without scallops. Whelks spent more time in low versus high-density plots, but consumed far more scallops in the latter. In trials without scallops, whelk movement rates were 5 × higher, presumably due to increased exploratory behavior. Overall, whelks were most active during crepuscular hours and during periods of increasing wind speeds. Our results, combined with population abundance data, suggest that whelks (especially B. carica) are drawn to planted bay scallop aggregations, but probably contribute to relatively low overall mortality in the context of restoration efforts. [ABSTRACT FROM AUTHOR]

Retinoid X receptor (RXR) has been found to be a major target in various processes of endocrine disruption from the exposure to organotin compounds (OTCs), including imposex in gastropod mollusks. It was also reported in bivalves that OTCs caused intersex and skewed sex ratio. In order to evaluate the effect of these ligand-like OTCs, we constructed a reconstituted yeast system (CfRE system) based on GAL4 yeast two-hybrid principle using scallop Chlamys farreri retinoid X receptor (CfRXRa) and retinoid X response element (RXRE) to investigate the ligand-induced transactivation of CfRXRa. Responses of CfRXRa to 9-cis retinoic acid (9cRA) and tested four OTCs showed concentration-dependent response which is comparable with reported RXRa in vitro assay of human and gastropods. The detective limits of the CfRE system were found to be 100 nM for 9cRA and 10–1000 nM for the tested OTCs. While the tested non-Sn endocrine disrupting chemicals, including Benzo[a]pyrene, 2,4-Dichlorophenol, Nonylphenol, and Tetrabromobisphenol A, showed no effect on CfRXRa response. The present assay system may provide a valuable tool for screening assessments of unidentified environmental ligand chemicals on bivalve mollusks. It is also useful for comparison of sensitivity differences among species exposed to EDCs. [ABSTRACT FROM AUTHOR]

Summary: Scallops are the third largest aquaculture mollusks product, while they are highly perishable during storage. The main purpose of the present study was to evaluate the effect of high pressure processing (HPP) on physicochemical and sensorial properties of scallop (Mizuhopecten yessoensis) during refrigeration storage. The scallop adductor muscle was treated with different pressures (200, 300, 400 and 500 MPa, 5 min) and iced storage for 28 days. Results showed that HPP delayed microbial growth as pressure increased. HPP (≥400 MPa) resulted in myosin and actin denaturation, increased hardness, whiteness, pH and promoted water migration. However, preliminary sensory analysis showed no significant difference between pressure‐treated and control adductor muscles in appearance, odour, texture and overall acceptability after cooking. In addition, pressure‐treated adductor muscles (≥300 MPa) remained edible after 28 days of storage. Overall, these results can provide basic knowledge for the storage of pressure‐treated scallop meat. [ABSTRACT FROM AUTHOR]

The Peruvian scallop (Argopecten purpuratus, Lamarck 1989) is a marine bivalve of high commercial value in the aquaculture industry, with wild populations distributing from northern Peru to Chile. Growing demand for it in the world aquaculture markets and limited availability of hatchery‐based seeds caused long‐term seed translocations among wild populations to recover depleted local populations and for production needs. We investigated long‐term translocation effects on the genetic diversity and structure of wild populations using next‐generation RAD sequencing. We sampled individuals from Sechura, Lobos de Tierra, Samanco, and Bahia Independencia in Peru, and La Rinconada in Northern Chile. We identified 8,345 polymorphic RAD loci and 24,218 SNPs for the five populations. We estimated high observed heterozygosity for all populations and high SNP frequency compared to similar studies on marine bivalves. We detected no spatial divergence among populations in Peru (pairwise FST from 0 to 0.003), but strong differentiation with the population in Chile. Migration rate estimates suggested asymmetric directionality of seed translocation. Overall, our results support a remnant effect of an intense historic translocation and ongoing gene flow among wild populations in Peru, challenging the identification of outlier loci and certification of sustainable origin of cultured scallops using genetic markers. [ABSTRACT FROM AUTHOR]

The settlement of molluscs’ larvae of and other biofouling organisms on experimental collectors was studied, with particular reference Great Mediterranean scallop, Pecten jacobaeus. Three types of experimental collector made from vegetable sacks, modelled based on the collectors used in Japan, were placed in four existing fish and shellfish farms located in the Boka Kotorska Bay. The experimental collectors were placed in the periods June–October and June–December 2017 and the period August 2017–February 2018 and monitored after immersion of four to six months, respectively. In total, 18 species of molluscs and also 28 species of biofouling organisms were determined. The most abundant ones found on the collectors were the following shellfish species (68 %) Talohlamys multistriata, Mytilus galloprovincialis, Modiolarca sp., Anomia ephippium and Limaria hians. The most abundant group of biofouling organisms were crustaceans (18 percent) with a species of porcelain crab, Pisidia longicornis, and tunicates (5 percent) with the species Phallusia mammillata and Ascidia mentula. The main target species, Great Mediterranean scallop, was most abundant on collector Type II, with 28 individuals. From three types of experimental collectors used in the process of collecting larvae of shellfish and biofouling species, collector type-I and type-II proved to be a more suitable basis for receiving larvae of shellfish due to the unimpeded flow of sea water that allows their successful growth and development. Species Talochlamys multistriata, were found in great abundance and it could be good candidate to diversify the aquaculture production, thus potentially offering farmers an additional source of income. [ABSTRACT FROM AUTHOR]

Cell cultures can simplify assays of biological phenomena; therefore, cell culture systems have been established for many species, even invertebrates. However, there are few primary culture systems from marine invertebrates that can be maintained long term. The Japanese scallop, Patinopecten yessoensis, is a marine bivalve. Cell culture systems for the scallop have only been established for a few organ‐derived cell types and for embryonic cells. We developed a primary culture system for cells from male and female scallop gonads, hepatopancreas, and adductor muscle by utilizing culture conditions closer to those in nature, with regard to temperature, osmolarity, and nutrition. Primary cultured female gonadal cells were maintained for more than 1 month and had potential for proliferation. Furthermore, a genetic transfection system was attempted using a scallop‐derived promoter and a lipofection reagent. GFP‐positive cells were detected in the attempt. These technical developments would promote our understanding of biochemical mechanisms in scallops as well as providing clues for establishment of immortalized molluscan cell lines. [ABSTRACT FROM AUTHOR]

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Transcriptional coactivator p15 (PC4) encodes an effectively diverse protein with highly conserved structure and performs critical functions in RNA polymerase II-mediated transcription, DNA replication and damage repair. Although comprehensive investigations of PC4 have been characterized in most vertebrates and some invertebrates, the crucial roles of PC4 were less systematically validated in bivalve mollusks. In the present study, the function of PC4 , particularly Arg0230340.1 which had been identified to be highly associated to thermotolerance, in bay scallops Argopecten irradians irradians (AiPC4s) was verified through suppression of Arg0230340.1 expression with dsRNA-mediated RNAi (5 μM, 10 μM and 20 μM). Then, expression regulations of AiPC4s in temperature sensitive tissues (heart, mantle and gill) and cardiac performance including resting heart rate (RHR), maximum heart rate (HR max) and Arrhenius break temperature (ABT) of bay scallops were detected 24 h after injection of siRNA. After interference, Arg0230340.1 displayed an obvious decrease in experimental groups (5 μM, 10 μM and 20 μM) relative to that in control (NG) and blank groups (DG). Simultaneously, the suppression of Arg0230340.1 expression resulted in a significant decrease of HR max in experimental groups, but with no marked differences for RHR among groups. Importantly, the suppression of Arg0230340.1 significantly weakened the thermotolerance of bay scallops, as proven by a reduction up to 4.09 °C of ABT in experimental groups (5 μM–28.09 ± 1.46 °C, 10 μM–27.33 ± 0.09 °C, 20 μM–27.31 ± 0.21 °C) than that in NG (31.60 ± 0.05 °C)/DG (31.73 ± 0.01 °C). Interestingly, the suppression of Arg0230340.1 resulted in functional compensation and cross-regulation among AiPC4 family members, displaying a tissue-specific expression regulation profile. Moreover, contributions of AiPC4s to thermotolerance in bay scallops suggested that Arg0230340.1 displayed a dominating contribution to ABT in heart (58.47%) and mantle (48.32%), whereas Arg0159040.1 contributed to the highest degree (59.25%) in gill. This work verified the leading role of Arg0230340.1 and its diverse interaction with other AiPC4s in thermotolerance of bay scallops, providing clues for elucidating the tissue-specific regulation of compensation effect of AiPC4s and proving the feasibility of AiPC4s as a candidate gene for the breeding of thermal-tolerant scallops. • DsRNA-mediated RNAi of Arg0230340.1 was conducted for AiPC4s ' function verification. • Arg0230340.1 displayed an obvious down-regulation expression after RNAi. • Suppression of Arg0230340.1 caused functional compensation and cross-regulation among AiPC4s , with tissue-specific patterns. • Repression of Arg0230340.1 led to significant decreases of HR max and ABT values. • This work verified the leading role of Arg0230340.1 and diverse interactions among AiPC4s in thermotolerance of bay scallops. [ABSTRACT FROM AUTHOR]

Paralytic shellfish toxins (PSTs) produced by some marine dinoflagellates can cause severe human intoxication via vectors like bivalves. Toxic dinoflagellate Gymnodinium catenatum produce a novel group of hydroxybenzoate PSTs named GC toxins, but their biokinetics in bivalves haven't been well examined. In this experiment, we analyzed PSTs in bay scallops Argopecten irradians exposed to G. catenatum (strain MEL11) to determine their accumulation, elimination, anatomical distribution, and biotransformation. To our surprise, up to 30% of the PSTs were accumulated in the adductor muscle of scallops at the end of the experiment, and the toxicity of adductor muscle exceeded the regulatory limit of 800 μg STXeq/kg in only 6 days. High concentration of toxins in the adductor muscle are likely linked to the rapid transfer of GC toxins from viscera to other tissues. Moreover, most GC toxins in scallops were found rapidly transformed to decarbamoyl toxins through enzyme-mediated hydrolysis, which was further supported by the in vitro incubation experiments. Our study demonstrates that GC toxins actively participate in toxin distribution and transformation in scallops, which may increase the risks of food poisoning associated with the consumption of scallop adductor muscle. The negative impacts of harmful algal blooms (HABs) have become a global environmental concern under the joint effects of cultural eutrophication and climate change. Our study, targeted on the biokinetics of paralytic shellfish toxins in scallops exposed to Gymnodinium catenatum producing unique GC toxins, aims to elucidate potential risks of seafood poisoning associated with GC toxins. The findings of this study will help us to understand the roles of GC toxins in seafood poisoning, and to develop effective management strategies against toxic algal blooms and phycotoxins. [Display omitted] • Gymnodinium catenatum producing GC toxins were fed to scallop Argopecten irradians. • Up to 30% of PSTs ingested by scallops were accumulated in the adductor muscle. • Biokinetic model indicated a high PST transfer rate from viscera to adductor muscle. • Most GC toxins undergo enzymatic hydrolysis to form decarbamoyl toxins in scallops. • GC toxins will affect scallop toxicity through tissue transfer and transformation. [ABSTRACT FROM AUTHOR]

The tumor necrosis factor (TNF) receptor-associated factor (TRAF) family has been reported to be involved in many immune pathways. In a previous study, we identified 5 TRAF genes, including TRAF2, 3, 4, 6, and 7, in the bay scallop (Argopecten irradians , Air) and the Peruvian scallop (Argopecten purpuratus , Apu). Since TRAF6 is a key molecular link in the TNF superfamily, we conducted a series of studies targeting the TRAF6 gene in the Air and Apu scallops as well as their hybrid progeny, Aip (Air ♀ × Apu ♂) and Api (Apu ♀ × Air ♂). Subcellular localization assay showed that the Air-, Aip-, and Api-TRAF6 were widely distributed in the cytoplasm of the human embryonic kidney cell line (HEK293T). Additionally, dual-luciferase reporter assay revealed that among TRAF3, TRAF4, and TRAF6, only the overexpression of TRAF6 significantly activated NF-κB activity in the HEK293T cells in a dose-dependent manner. These results suggest a crucial role of TRAF6 in the immune response in Argopecten scallops. To investigate the specific immune mechanism of TRAF6 in Argopecten scallops, we conducted TRAF6 knockdown using RNA interference. Transcriptomic analyses of the TRAF6 RNAi and control groups identified 1194, 2403, and 1099 differentially expressed genes (DEGs) in the Air, Aip, and Api scallops, respectively. KEGG enrichment analyses revealed that these DEGs were primarily enriched in transport and catabolism, amino acid metabolism, peroxisome, lysosome, and phagosome pathways. Expression profiles of 28 key DEGs were confirmed by qRT-PCR assays. The results of this study may provide insights into the immune mechanisms of TRAF in Argopecten scallops and ultimately benefit scallop breeding. • TRAF6 is localized in the cytoplasm of the scallops. • Overexpression of TRAF6 significantly activated NF-κB activity in a dose-dependent manner. • TRAF6 induced much higher NF-κB activations in hybrids than in the bay scallops. • TRAF6 seems to mainly function through pathways involving inhibition of IFN and p53 and stimulation of MyD88 and NF-κB. [ABSTRACT FROM AUTHOR]

Biofilms strongly influence bivalve settlement patterns on artificial substrates; however, their structure and taxonomic composition remains a black box. We characterized a natural biofilm composition that exhibits a large settlement of larvae of the Peruvian scallop Argopecten purpuratus by culture-dependent and culture-independent methods. Thirty-two different strains, representing six genera (10 strains of Bacillus, 9 of Vibrio, 6 Acinetobacter, 4 Staphylococcus, 2 Photobacterium, and 1 Exiguobacterium) were isolated. Those strains represented only 1.09% of the relative abundance compared with the total microbiota obtained by 16S rRNA high-throughput sequencing. The metagenomic analysis identified 441 species. Prokaryotes were predominant (93.4%) over eukaryotes (6.6%), with Pelobacter (13.4%), Lewinella (5.6%), Marinobacter (5.4%), Hoeflea (4.2%), and Microcystis (3.1%) being the most representative genera. Laser scanning confocal microscopy (LSCM) imaging evidenced an irregular and heterogeneous biofilm with an average thickness of 35 µm, where the heterotrophic prokaryotic community (3.4x106 cell cm-2) dominate the photoautotrophic communities (2.3x105 cell cm-2). For the first time, an A. purpuratus settlement-related biofilm was described by the next generation sequencing tool (NGS) and compared with traditional methodologies. [ABSTRACT FROM AUTHOR]

Tentacles are fascinating, multifunctional organs found in many aquatic invertebrate groups. In bivalves, tentacles are morphologically diverse, performing protective and sensory roles in taxa from different ecological niches. Such diversity is particularly accentuated in Pteriomorphia, a clade comprising scallops, oysters, file clams, and relatives. However, little is known about the evolution of these organs and their role in bivalve radiation. To test hypotheses of convergent tentacular evolution and a possible association between tentacles and body orientation on the substrate, we first examined tentacle morphology in 108 preserved species representing 15 families across Pteriomorphia. Morphological descriptions of tentacle type (inner mantle fold tentacles, IFT; middle mantle fold tentacles, MFT) and position (marginal and submarginal) are provided, expanding the knowledge of less studied bivalve taxa. Then, we placed the morphological dataset under a molecular phylogenetic framework to estimate ancestral states. IFT had likely four independent origins, while MFT emerged twice independently. After being gained, tentacles have not been lost. In addition, evolution of MFT coincides with transitions in body position with the midsagittal plane parallel to the substrate in the clades of scallops (Pectinida) and oysters (Ostreida). Such a shift could be related to the increase of mantle exposure, favoring the emergence of serially repeated organs, such as tentacles. Altogether, our results support the convergent evolution of tentacles across different taxonomic levels, corroborating the plasticity of the molluscan body and the relevance of evolutionary convergences in the radiation of bivalves. [ABSTRACT FROM AUTHOR]

Some harmful algal blooms produce lipophilic marine biotoxins (LMTs) such as okadaic acid (OA; and its analogs dinophysistoxins [DTXs]), yessotoxins (YTXs), pectenotoxins (PTXs), and azaspiracids (AZAs), all of which may accumulate in filter-feeding bivalve mollusks. European health regulations stipulate a limit of 160 μg/kg for OA or DTXs, PTXs, and AZAs and 3.75 mg/kg for YTXs. Argopecten purpuratus is a valuable commercial marine bivalve exploited in Peru. Despite its importance and the periodic reports of the presence of harmful algal blooms in Peruvian coastal waters, information regarding potential contamination of these scallops by LMTs is lacking. We evaluated LMTs in 115 samples of A. purpuratus collected between November 2013 and March 2015 from 18 production areas distributed along the Peruvian coast. The hepatopancreas, which accumulates most of the toxins in the scallop, was analyzed with liquid chromatography–tandem mass spectrometry to quantify OA in its free form, YTX, AZA-1, and PTX-2. Baseline separation was achieved in 19 min. Linearity (R2 > 0.997), precision (coefficient of variation < 15%), and limits of quantification (0.155 to 0.479 ng/mL) were satisfactory. YTX was found in 72 samples, and PTX-2 was found in 17 samples, but concentrations of both biotoxins were below the regulatory limits. Free OA and AZA-1 were not detected in the scallop samples. This atypical profile (i.e., presence of PTX-2 and absence of OA) may be linked to the presence of the dinoflagellate Dinophysis acuminata. The production of YTX could be associated with the phytoplankton Gonyaulax spinifera and Protoceratium reticulatum. This is the first systematic assessment of the four types of LMTs in shellfish from Peruvian coastal waters. The results suggest low prevalence of LMTs in Peruvian bay scallops but support continued surveillance and analysis of LMTs in Peru. YTX was found for the first time in scallops from Peruvian coastal waters. Free OA and AZA-1 were not detected in any scallop sample. PTX-2 co-occurred with YTX in the scallops. The highest concentrations of YTX and PTX-2 were below European regulatory limits. [ABSTRACT FROM AUTHOR]

Coastal hypoxia can negatively impact shellfish, but it is unclear if exposure to intensifying diel-cycling hypoxia alters shellfish susceptibility to severe hypoxic events in late summer. In this study, bay scallops (Argopecten irradians) were acclimatized for 50 days at 5 sites along a eutrophication gradient, where scallops rarely, occasionally and frequently encountered hypoxic conditions. In a laboratory experiment, scallops were then exposed to a 24-h hypoxic event and heartbeat rates were recorded with non-invasive infrared sensors during the initial oxygen decline, during extended hypoxia, and for one hour after re-establishment of normoxia. Irrespective of acclimatization site, scallops sustained increased heartbeat rates during hypoxia, but cardiac responses were less pronounced in scallops that frequently encountered hypoxia during acclimatization. This study suggests that cardiac responses to changes in dissolved oxygen concentrations can be affected by exposure history, which may have important ramifications for scallop ecophysiology and resilience in dynamic coastal environments. [ABSTRACT FROM AUTHOR]

A survey of fresh great Mediterranean scallops (Pecten jacobaeus) and frozen queen scallops (Aequipecten opercularis) collected from the northern Adriatic Sea demonstrated the presence of nematode larvae that were morphologically and molecularly identified as Sulcascaris sulcata. The presence of this nematode in the northern Adriatic Sea has been described in the loggerhead sea turtle, which is the final host, but it was only recently described in the intermediate molluscan host. Affected scallops present rust-brown lesions in the adductor muscle. In this study, necroscopic and histopathological lesions are described in affected scallops. Furthermore, the detrimental effects of this parasite on the commercialization of scallops under the current European legislation concerning the hygiene of seafood products are evaluated. [ABSTRACT FROM AUTHOR]

The great scallop (Pecten maximus) is a commercially important bivalve in Europe, particularly in the English Channel, where fisheries are managed at regional and local scales through the regulation of fishing effort. In the long term, knowledge about larval dispersal and gene flow between populations is essential to ensure proper stock management. Yet, previous population genetic studies have reported contradictory results.In this study, scallop samples collected across the main fishing grounds along the French and English coasts of the English Channel (20 samples with temporal replicates for three sites, n = 1059 individuals), and the population genetic structure was analysed using 13 microsatellite loci. Coupling empirical genetic data with demogenetic modelling based on a biophysical model simulating larval exchanges among scallop beds revealed a subtle genetic differentiation between south‐west English populations and the rest of the English Channel, which was consistent with larval dispersal simulations.The present study provides a step forward in the understanding of great scallop population biology in the English Channel, underlining the fact that even in a context of potentially high gene flow and recent divergence times since the end of the last glacial maximum, weak but significant spatial genetic structure can be identified at a regional scale. [ABSTRACT FROM AUTHOR]

In the present work, the relative effects of the season (early vs. late summer), site (Gulf vs. Pacific study sites), the population of origin (Gulf vs. Pacific) and associated abiotic variables were determined in two geographically-separated Nodipecten subnodosus populations and their reciprocal transplants, through the scope for growth (SFG) and net growth efficiency (K2) using a portable open-flow system. Results indicate that both energy acquisition and expenditure were significantly affected by season, site, and population factors. Scallop energy acquisition and growth efficiency were highest during the earlier, cooler part of the summer and higher at the Pacific site where food availability was highest. Significantly higher respiration rates were measured for the Pacific scallop population, leading to significantly lower net growth efficiency than scallops of Gulf origin, which indicates a physiological advantage for Gulf scallops during the suboptimal growth conditions present during summer months on both coasts of the Baja California peninsula. It may have important implications for aquaculture enterprises in this region, and may also confirm the genetic divergence between these two geographically separated populations. The advantages of the open-flow system for in situ ecophysiological studies in aquatic organisms are discussed. [ABSTRACT FROM AUTHOR]

In our ongoing bay scallop restoration efforts in eastern Long Island, NY, United States, we have planted millions of hatchery‐reared juveniles to serve as broodstock when they mature. These plantings have driven the resurgence of larval recruitment, benthic population sizes, and commercial fishery landings over a 12‐year period. In this article, we detail an attempt to track the contribution of our restoration efforts to population rebuilding using planted "skunks," an uncommon color morph, by looking for increased skunk frequencies in subsequent wild cohorts. Although we saw higher skunk frequencies among large juveniles in natural populations in the first 3 years after extensive skunk plantings, supporting use of uncommon color morphs as a passive tracer, this conclusion was not supported when examined over a 12‐year period, as no strong correlations were seen between skunk frequencies at different life stages (adult broodstock, small and large F1 juveniles, F1 adults) for respective cohorts. Potential reasons for poor correlation between skunk frequencies and restoration efforts include lower than expected production of skunk offspring, dilution of out‐planted contribution to growing natural populations, interannual variability in skunk frequencies that may have obscured the expected skunk signal, and/or differentially higher mortality of skunks at postset and larger juvenile stages. In the latter case, skunks experienced higher overwinter mortality, most likely due to predation, in 9 of 11 years. This led us to suspend skunk plantings after 3 years. Nevertheless, commercial fishermen perceived skunks to be "our" scallops, helping raise the profile of and support for our restoration efforts. [ABSTRACT FROM AUTHOR]

Scallop farming is the main economic activity in the northern parts of China, with a production that has increased quickly since the 1980s. In the present study, a bioenergetics growth model to the Yesso scallop, Patinopecten yessoensis, in the mariculture area of Zhangzidao Island was applied, based on dynamic energy budget (DEB) theory which describes energy flux variation through different compartments of the scallop body. Estimates of most DEB parameters were based on available physiological data or published information, and the two parameters, i.e., detritus contribution to food (αDet) and half-saturation constant for food (XK) were calibrated using datasets in this study. The model relied on two forcing variables: water temperature and food density expressed by different food quantifiers. The sets of data used to validate the model came from a growth experiment performed on P. yessoensis for bottom-sowing culture. The DEB model developed here for P. yessoensis was allowed to simulate growth and reproduction of the scallop in the growing area of the Zhangzidao Island. [ABSTRACT FROM AUTHOR]

This paper proposed a method to determine the path scallop of toroidal cutter in five-axis milling during a complex surface machining. A mathematical algorithm was developed by taking into consideration the impact of the helical angle and inclination angle. The applicability of the proposed method was tested using two model parts with diverse surface profiles. The result showed that the method was effectively used to generate the path scallop data. Moreover, the program simulation could also generate the shape of a machined surface. The effect of the helical angle to the scallop height was also tested and the result showed that the helical angle tended to decrease the scallop height. On the other hand, a larger inclination angle produced a larger scallop height. The verification test using Siemens-NX proved that the method was accurate. [ABSTRACT FROM AUTHOR]

Cross‐breeding has been successfully applied in agriculture and aquaculture industries to improve important production traits. In our previous studies, we produced the F1 hybrids with high heterosis in growth by crossing the bay scallops with the Peruvian scallops and selected a new strain, Bohai Red, from the F1 hybrids. In this study, we selected another new strain from the backcross (BC1) of the F1 hybrids with bay scallops. The base cohort (G0) was size‐selected from the BC1, and the G1, G2, G3 and G4 cohorts were produced with size‐selected brood stocks from the G0, G1, G2 and G3 cohorts respectively. Our results showed that average shell height, shell length, shell width and whole body weight of the G4 cohort were increased by 16.8%, 16.8%, 11.5% and 43.6%, respectively, compared with the unselected control group of bay scallop. This new strain has now become one of the major cultured Argopecten scallops in northern China waters and was later named QN‐2. [ABSTRACT FROM AUTHOR]

Temperature is a critical factor affecting the growth, development and reproduction of aquatic organisms. The interspecific F 1 hybrids between hermaphroditic bay scallops (Argopecten irradians) and Peruvian scallops (Argopecten purpuratus) exhibited significant heterosis in yield, but sterility in most hybrids hindered large scale interspecific hybridization and speciation. We first explored the physiological effect of temperature on the fertility of hybrid hermaphroditic Argopecten scallops with F 1 hybrids treated at 6 different temperatures (18 °C, 20 °C, 22 °C, 24 °C, 26 °C, and 28 °C). The results showed that the final mortality rates from 18 °C to 22 °C were significantly lower than those from 24 °C to 28 °C. With the decrease of the temperature, the size, gonadal index, ATP content, and expression of most genes related to fertility regulation gradually decreased in F 1 hybrids treated at 22 °C, 20 °C and 18 °C, and the apoptosis rate of oocytes gradually increased, but the activity of SOD (superoxide dismutase) and CAT (catalase) first increased and then decreased. The fertility of hybrids treated at 22 °C, 20 °C and 18 °C gradually decreased with the decrease of the temperature. According to gene expression, temperature may regulate the fertility of Argopecten F 1 hybrids by affecting apoptosis, meiosis, ATP production and damage repair to inhibit the genesis and maturation of germ cells. Our findings suggest that temperature can affect the hybrid fertility of hermaphroditic Argopecten scallops and provide the basis for further research on the mechanism of temperature on sterility. • Effect of temperature on fertility of hybrid hermaphroditic Argopecten scallops was first explored. • 22 °C may be a better cultivation temperature to obtain higher fertility. • Temperature affects the level of apoptosis and growth of hybrid scallops. • Temperature affects gonadal development and fertility of hybrid scallops. [ABSTRACT FROM AUTHOR]

To identify the most suitable model to describe the growth of the selected strain of scallop "Hongmo No. 1" (Bohai Red♂ X Argopecten irradians concentricus ♀), we analyzed the length/weight-at-age data of scallops reared communally in the same sea area. Our goal was to evaluate the influence of the autumn-winter-spring and spring-summer-autumn cultivation seasons on condition factors and established growth models (logistic, Gompertz, Von Bertalanffy, and Brody). We used three condition factors and the actual cultivation situation to assess the ability of the models to predict future growth. The results showed that growth performance in autumn-winter-spring is better than that during spring-summer-autumn in terms of shell length, shell height, shell width, body weight, adductor muscle weight, shell weight, and survival rate (P < 0.05). As a consequence of the study, it was determined that the Gompertz model best fit the shell length and logistic model best fit body weight in autumn-winter-spring. In addition, the Von Bertalanffy model best fit shell length and the logistic model best fit body weight in spring-summer-autumn. Our results suggest that the selected strain of scallop "Hongmo No. 1" grows better in autumn-winter-spring than spring-summer-autumn. These findings can be used to improve and promote its cultivation in southern waters. • The beneficial effect of choice of model on growth performance was significant for different cultivation seasons. • Comparing with the two cultivation seasons, autumn is more suitable for growth and adaptability than spring. • For the first time, a selected strain is used to analyse the growth curve in different cultivation seasons. [ABSTRACT FROM AUTHOR]

In this study, the effects of high pressure homogenization (HPH) (0, 20, 40, 60, 80 and 100 MPa) on physicochemical and emulsifying properties of scallop (Chlamys farreri) protein (CFP) solutions were investigated. With the increasing of homogenize pressure, CFP solutions have better solubility. HPH could significantly decrease the particle size, which is distributed mainly in 300–600 nm. Compared with other treatments, HPH at 100 MPa showed highest surface hydrophobicity index (H 0) (131.22 ± 2.22), higher nitrogen soluble index (NSI) (92.72 ± 0.53%) and higher free sulfhydryl group (3.97 ± 0.20 μmol/g protein). Circular dichroism (CD) inspections showed that 100 MPa of high pressure homogenization could make the random coil component decrease and the β-sheet component increase. The adsorbed proteins (AP %) of the emulsions progressively increased from 39.69 ± 0.11% to 61.89 ± 1.01% with the pressure of homogenization increasing from 20 to 100 MPa. Most of the proteins in the emulsions were adsorbed after HPH. Laser scanning confocal microscopy (LSCM) showed stability of the emulsion was increased by HPH. This work showed that HPH treatment has positive effects on physiochemical and emulsifying properties of CFP for innovative technologies for the potential industrial applications. Image 1 • Physicochemical properties of CFP were changed by the combination of shear and cavitation. • HPH did not affect the protein composition of CFP. • A sharp increase of hydrophobicity was found after HPH. • The difference protein distributions between the cream and aqueous phases were clarified. • A uniform dispersion of emulsion was visualized after HPH. [ABSTRACT FROM AUTHOR]

Two new scallop strains, the 'QN Orange' scallop and the 'Bohai Red' scallop, were selected from the hybrid cohort between the bay scallop (Argopecten irradians irradians) and the Peruvian scallop (Argopecten purpuratus) to improve the bay scallop stock, which has suffered from significant inbreeding depression characterized by poor growth and high mortality. Although both strains were originated from the same hybrid cohort, the 'QN Orange' scallops possess orange adductor muscles while the 'Bohai Red' scallops have white adductor muscles. To explore the pigment profiles of adductor muscle coloration in these two scallop strains, an optimized method based on liquid chromatography coupled with triple quadrupole mass spectrometry (HPLC-QqQ-MS) with atmospheric pressure chemical ionization (APCI) was established to determine chlorophyll (chlorophyll a and chlorophyll b) and carotenoids (including α-carotene, β-carotene, ε-carotene, γ-carotene, ζ-carotene, lutein, fucoxanthin, zeaxanthin, canthaxanthin, pectenoxanthin, and pectenolone). The results showed that the total contents of carotenoids in the adductor muscle, gill, and mantle of 'QN Orange' scallops were 82.68, 105.49, and 100.49 μg g−1, which were 49.88, 3.26, and 4.18 times higher than those in the 'Bohai Red' scallops, respectively. In particular, the contents of the pigments pectenolone, pectenoxanthin, fucoxanthin, zeaxanthin, and lutein in the 'QN Orange' scallops were 171.58, 61.67, 3.87, 22.16 and 23.27 μg g−1, which were 6.92, 3.38, 27.64, 15.75, and 13.00 times higher than those in the 'Bohai Red' scallops, respectively. These results suggest that the orange coloration in the 'QN Orange' scallops might be caused by the accumulation of carotenoids. • A method of HPLC-QqQ-MS was established to determine 13 pigments in the 'Bohai Red' scallops and 'QN Orange' scallops. • The content of carotenoids in the 'QN Orange' scallop was higher than that in the 'Bohai Red' scallop. • The orange coloration in the 'QN Orange' scallops might be caused by the accumulation of carotenoids. [ABSTRACT FROM AUTHOR]

A combined analysis of measurements of shell morphology and oxygen isotopic composition in shells of Swiftopecten swiftii (Bernardi, 1858) revealed that the step-like growth of commarginal ridges correspond to annual fluctuations in water temperature. The main role of these cyclically-formed ridges may be to enlarge the internal volume of the shell rapidly in time with gonad maturation. The sexual difference in shell width is correlated with the significantly larger size of the ovary in comparison with the testis; valves of the females had a more prominent bulge than those of the males. This type of dimorphism is very rare among bivalves and is the first example reported in the order Pectinoida. Results of detailed oxygen isotopic analysis in both sexes indicate that step-like commarginal ridge formation occurs in winter. In addition, a drastic change in the direction of growth was observed in the middle of December in the males and in November in the females. This is consistent with the possibility that the female needs a longer time to develop a larger gonad. We conclude that the sexual difference in energy invested in reproduction reflects the differential production of shell during the breeding season. [ABSTRACT FROM AUTHOR]