Bay Scallop Argopecten Irradians Research Articles

Morphometric Analysis of Two Shell Color Strains of the Bay Scallop Argopecten irradians

Morphometric Analysis of Two Shell Color Strains of the Bay Scallop Argopecten irradians

Tissue-Specific and Time-Dependent Expressions of PC4s in Bay Scallop (Argopecten irradians irradians) Reveal Function Allocation in Thermal Response.

Transcriptional coactivator p15 (PC4) encodes a structurally conserved but functionally diverse protein that plays crucial roles in RNAP-II-mediated transcription, DNA replication and damage repair. Although structures and functions of PC4 have been reported in most vertebrates and some invertebrates, the PC4 genes were less systematically identified and characterized in the bay scallop Argopecten irradians irradians. In this study, five PC4 genes (AiPC4s) were successfully identified in bay scallops via whole-genome scanning through in silico analysis. Protein structure and phylogenetic analyses of AiPC4s were conducted to determine the identities and evolutionary relationships of these genes. Expression levels of AiPC4s were assessed in embryos/larvae at all developmental stages, in healthy adult tissues and in different tissues (mantles, gills, hemocytes and hearts) being processed under 32 °C stress with different time durations (0 h, 6 h, 12 h, 24 h, 3 d, 6 d and 10 d). Spatiotemporal expression profiles of AiPC4s suggested the functional roles of the genes in embryos/larvae at all developmental stages and in healthy adult tissues in bay scallop. Expression regulations (up- and down-) of AiPC4s under high-temperature stress displayed both tissue-specific and time-dependent patterns with function allocations, revealing that AiPC4s performed differentiated functions in response to thermal stress. This work provides clues of molecular function allocation of PC4 in scallops in response to thermal stress and helps in illustrating how marine bivalves resist elevated seawater temperature.

Making connections: predatory behavior, prey availability and environment. Editorial comment on the highlight article “Predation on planted and wild bay scallops (Argopecten irradians irradians) by busyconine whelks: studies of behavior incorporating acoustic telemetry” by M. Sclafani et al. 2022

Making connections: predatory behavior, prey availability and environment. Editorial comment on the highlight article “Predation on planted and wild bay scallops (Argopecten irradians irradians) by busyconine whelks: studies of behavior incorporating acoustic telemetry” by M. Sclafani et al. 2022

Predation on planted and wild bay scallops (Argopecten irradians irradians) by busyconine whelks: studies of behavior incorporating acoustic telemetry

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.

Effects of salinity changes on the osmoregulatory and stress responses in the bay scallop Argopecten irradians

Effects of salinity changes on the osmoregulatory and stress responses in the bay scallop Argopecten irradians

Exposure to benzo[α]pyrene causes oxidative stress and cell damage in bay scallop Argopecten irradians

In the present study, bay scallop antioxidant response to acute exposure to the benzo[α]pyrene (BaP; a type of polycyclic aromatic hydrocarbon) was investigated. Scallops were exposed to doses of 0.5 and 1.0 µg/L (low-dose group) and 10 and 50 µg/L (high-dose group) for 72 h. The following oxidative stress indicators were measured in the digestive diverticula tissues or hemolymph: superoxide dismutase, catalase, hydrogen peroxide, and lipid peroxidation. The apoptotic response in the high dose group was assessed using terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) assay. The stress indicators in each group increased significantly with time, except in the 0.5 µg/L group. The TUNEL assay revealed that more apoptotic cells were detected after exposure to BaP over time. These results suggest that exposure to BaP induces oxidative stress and causes tissue damage in bivalves. These findings also revealed that high concentrations of BaP exposure can have potential adverse effects (apoptosis and cell damage) in bivalves. Additionally, these results might shed some new light on the ecotoxicological effects of BaP on marine bivalves.

Acclimatization in the bay scallop Argopecten irradians along a eutrophication gradient: insights from heartbeat rate measurements during a simulated hypoxic event

ABSTRACT 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.

Response to selection for growth in the second generation of two shell color lines of the bay scallop Argopecten irradians

The bay scallop Argopecten irradians is one of the most commercially important aquaculture species in China. A. irradians with two different shell color (red and black) from cultured stocks in China were used to establish two mass-selected strains (red shell line and black shell line) for fast growth, and a positive response to selection for fast growth was observed in the first generations. To determine whether continuous progress can be achieved by selection for growth, we evaluated response to selection for the second generations of the two shell color lines. At grow-out stage, a genetic gain of 13.23%–15.71%, selection response of 1.62–1.71 and realized heritability of 0.43–0.45 for shell length were observed in the selective breeding strains after two generations of selection. The current response to selection for growth obtained in the second-generation selection strains suggests that a large amount of genetic variance still remains in the selected strains and there is a potential for sustained genetic improvement in growth-related traits in these strains through selective breeding. The results obtained in this study provides important information for future breeding programs for A. irradians.

Effects of light-emitting diodes on thermally-induced oxidative stress in the bay scallop Argopecten irradians

ABSTRACTWater temperature is an important stressor that affects the physiological and biochemical responses of scallops. In this study, we investigated the effect of different light-emitting diodes (LEDs; red, green and blue) on oxidative stress in Argopecten irradians. PCR revealed MnSOD mRNA expression in the digestive diverticula, gill, adductor muscle and eye. CAT and HSP70 mRNA were expressed in the digestive diverticula, gill and adductor muscle. Additionally, we measured the changes in the expression of HSP70, MnSOD and CAT as well as H2O2 levels during thermal/laboratory stress. In the digestive diverticula, gill and adductor muscle, the mRNA expressions and activities and H2O2 levels significantly increased in response to thermal changes. The gene expressions and activities and H2O2 levels were significantly lower in scallops that received green LED light than in those that received no mitigating treatment. A comet assay revealed that thermal change groups had increased rates of nuclear DNA damage; however, treatment with green LED reduced the frequency of damage. The results indicated that low or high water temperature conditions induced oxidative stress in A. irradians but that green LED significantly reduced this stress.

Effects of Marine Toxin Domoic Acid on Innate Immune Responses in Bay Scallop Argopecten irradians

Domoic acid (DA) is an amnesic shellfish poisoning toxin produced by some species of the genera Pseudo-nitzschia and Nitzschia. This toxin has harmful effects on various species, especially scallops. This study aimed to investigate the effects of DA exposure on the immune and physical responses of bay scallop, Argopecten irradians. Various immunological and physical parameters were assessed (acid phosphatase (ACP), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), lipid peroxide (LPO), nitric oxide (NO), and the total protein content) in the haemolymph of scallops at 3, 6, 12, 24, and 48 h post-exposure to DA at different concentrations (10, 50, and 100 ng/mL). Moreover, the expression of immune-related genes (CLT-6, FREP, HSP90, MT, PGRP, and PrxV) was assessed. The activities of ACP, ALP, and LDH and the total protein content and LPO increased upon exposure to DA at different concentrations, while NO levels were decreased. Furthermore, immune-related genes were assessed upon DA exposure. Our results showed that exposure to DA negatively impacts immune function and disrupts physiological activities in bay scallops.

Core-shell nanospheres behind the blue eyes of the bay scallop Argopecten irradians.

The bay scallop Argopecten irradians (Mollusca: Bivalvia) has dozens of iridescent blue eyes that focus light using mirror-based optics. Here, we test the hypothesis that these eyes appear blue because of photonic nanostructures that preferentially scatter short-wavelength light. Using transmission electron microscopy, we found that the epithelial cells covering the eyes of A. irradians have three distinct layers: an outer layer of microvilli, a middle layer of random close-packed nanospheres and an inner layer of pigment granules. The nanospheres are approximately 180 nm in diameter and consist of electron-dense cores approximately 140 nm in diameter surrounded by less electron-dense shells 20 nm thick. They are packed at a volume density of approximately 60% and energy-dispersive X-ray spectroscopy indicates that they are not mineralized. Optical modelling revealed that the nanospheres are an ideal size for producing angle-weighted scattering that is bright and blue. A comparative perspective supports our hypothesis: epithelial cells from the black eyes of the sea scallop Placopecten magellanicus have an outer layer of microvilli and an inner layer of pigment granules but lack a layer of nanospheres between them. We speculate that light-scattering nanospheres help to prevent UV wavelengths from damaging the internal structures of the eyes of A. irradians and other blue-eyed scallops.

Transcriptomic and proteomic analyses of genetic factors influencing adductor muscle coloration in QN Orange scallops

BackgroundColor polymorphism, a high-valued trait, is frequently observed in molluscan shellfish. The QN Orange scallop, a new scallop strain successively selected from the interspecific hybrids of the bay scallop (Argopecten irradians irradians) and the Peruvian scallop (Argopecten purpuratus), is distinguished from other scallops by its orange adductor muscles. In this study, to reveal the mechanisms of the formation of adductor muscle coloration in the QN Orange scallops, we compared the proteome and transcriptome of orange adductor muscles of the QN Orange and those of white adductor muscles of the Bohai Red scallop, another strain selected from the interspecific hybrids of the bay scallop and the Peruvian scallop.ResultsTranscriptomic analysis revealed 416 differentially expressed genes (DEGs) between white and orange adductor muscles, among which 216 were upregulated and 200 were downregulated. Seventy-four differentially expressed proteins (DEPs), including 36 upregulated and 38 downregulated proteins, were identified through label-free proteomics. Among the identified DEGs and DEPs, genes related to carotenoids biosynthesis including apolipophorin, and Cytochrome P450 and those related to melanin biosynthesis including tyrosinase and Ras-related protein Rab-11A were found to express at higher levels in orange adductor muscles. The high expression levels of VPS (vacuolar protein sorting) and TIF (translation initiation factor) in orange adductor muscle tissues indicated that carotenoid accumulation may be affected by proteins outside of the carotenoid pathway.ConclusionsOur results implied that the coloration of orange adductor muscles in the QN Orange scallops may be controlled by genes modulating accumulation of carotenoids and melanins. This study may provide valuable information for understanding the mechanisms and pathways underlying adductor muscle coloration in molluscan shellfish.

Effect of modified clay on the transition of paralytic shellfish toxins within the bay scallop Argopecten irradians and sediments in laboratory trials

Shellfish aquaculture is an important marine industry that has been threatened by harmful algal blooms (HABs) and, in recent years, toxic HABs in particular. The modified clay (MC) treatment is the most promising method to mitigate HABs and has been frequently applied in the field. To determine how the application of MC affects the accumulation, transformation, and detoxification of paralytic shellfish toxins (PSTs) in the bay scallop Argopecten irradians and surrounding sediments, a series of experiments over 16 days in a laboratory simulated Alexandrium tamarense bloom were conducted. After 3 h of exposure to A. tamarense at 2070 (±120) cells mL−1, the toxicity level in the tissues of the scallops increased to 105.9 (±16.6) μg STX eq. 100 g−1 in the control group (group A, with no addition of MC), while the toxicity levels in the scallops of groups B and C (0.1 g L−1 and 0.5 g L−1 MC added, respectively) remained at relatively low levels. During the 3 h, the scallops in group A had incorporated 73.2 mol% of the toxin contained in the initial A. tamarense algal culture, the scallops in group B had incorporated 13.5 mol% of the toxin, and the scallops in group C showed almost no elevation in tissue toxin content. Meanwhile, 56.8 mol% and 107.1 mol% of the PSTs contained in the initial algal culture were settled in the sediments along with the MC-algal cells combination in group B and C, respectively. The results indicated that the application of MC can effectively prevent filter-feeding bivalves from ingesting toxic algal cells and decrease the accumulation of toxins by settling the toxic algal cells in the sediment. It was also indicated that the toxins accumulated within the sediments were more rapidly detoxified than that in the scallop tissues. Toxins accumulated by the scallops persisted in the tissue for approximately 16 days, while in the sediments, all of the PSTs contents were below the HPLC detection limits 4 days after the addition of MC.

경남 연안 해만 가리비(Argopecten irradians)의 부위별 마비성 패류독소 분포

To understand the characteristics of paralytic shellfish poisoning in a major production area of the bay scallop Argo pecten irradians in Korea, the seasonal variation and anatomical distribution of paralytic shellfish toxin (PST) were determined in bay scallops collected from the Gyeongnam coast of Korea from March to May 2018. PST levels in bay scallops in the survey area showed remarkable seasonal variation. PST was first detected at a level of 0.42 mg/kg on April 2, 2018, and the highest toxin level (3.15 mg/kg) was recorded on April 12. Among the tissues of bay scallops, the highest proportion of PST was found in the viscera (54.9%±17.8%), followed by the adductor (22.8%±10.9%), gonads (8.9%±4.6%), gills (7.1%±3.7%), and mantle (6.3%±.8%). In addition, with higher PST levels in the whole tissues of bay scallops, the proportion of PST in the viscera increased, whereas those in the mantle, gill, and gonad tissues decreased. In a high-toxicity group with more than 2.0 mg/kg PST in the whole tissues, the proportion of PST in the viscera was 71.8%±6.7%.

De novo transcriptome sequencing reveals candidate genes involved in orange shell coloration of bay scallop Argopecten irradians

Molluscan shell color has received persistent attention for its distinctive diversity and complexity. In the present study, six transcriptome libraries obtained from two developmental stages, pre-pigmentation and post-pigmentation, were used for paired-end sequencing in the bay scallop Argopecten irradians. In total, 289 839 646 paired-end reads were assembled into 70 929 transcripts. Using BLASTX and BLASTN, 30 896 unigenes were successfully annotated against the SWISS-PROT, NR, and KOG database. Gene ontology annotation and Kyoto Encyclopedia of Genes and Genomes classification identified numbers of unigenes involved in biomineralization and pigmentation. Digital gene expression analysis revealed that melanin, trace metal elements and porphyrins are potentially involved in shell coloration of A. irradians.

Impact of farming non-indigenous scallop Argopecten irradians on benthic ecosystem functioning: a case-study in Laizhou Bay, China

The farming of the non-indigenous bay scallop Argopecten irradians in coastal waters generates large amounts of biodeposits that potentially change the trophic pathways and quality of the benthic food web at lower trophic levels such as meiobenthos. To understand the trophic link between faecal pellets of bay scallop and meiobenthos in the aquaculture area, we investigated the resource use of harpacticoid copepods and nematodes inside and outside of 3 bay scallop farms in Laizhou Bay (Bohai Sea, China) using natural abundance of stable carbon and nitrogen isotopes together with fatty acid profiling. Faeces were found to be enriched in delta N-15 compared to all other food sources, which made faecal matter traceable. The enriched delta N-15 in several meiobenthos at the farms, together with the mixing model results, indicated that faeces could be a new food source for most of harpacticoid copepods and some nematodes. The quantities and the pathways of assimilation differed between the copepod families, depending on their feeding behaviors and the receiving environment. Furthermore, due to the presence of higher levels of polyunsaturated fatty acids, in particular docosahexaenoic acid, the dominant copepod family Canuellidae that abundantly consumed scallop faeces showed enhanced nutritional quality compared with those in the control sites. Thus, aquaculture of non-indigenous bay scallops provided a food source that was directly and indirectly consumed by meiobenthos underneath the scallop farms and improved the quality of lower level consumers as a food item in the benthic food web.

Sequence features, expression profiles and biochemical characteristics of a sigma class glutathione S-transferase gene (AiGSTσ) from bay scallop Argopecten irradians

Glutathione S-transferases (GSTs) are a class of enzymes that facilitate the detoxification of xenobiotics and also play important roles in innate immunity. In the present study, a novel sigma class GST gene (designated as AiGSTσ) was cloned from the bay scallop Argopecten irradians via rapid amplification of cDNA ends (RACE) technique. The complete cDNA sequence of AiGSTσ consisted of a 5’ untranslated regions (UTR) of 48 bp, a 3’ UTR of 113 bp with a poly A tail and an open reading frame (ORF) of 618 bp. The ORF encoded a polypeptide of 205 amino acid residues with a calculated molecular mass of approximately 23.11 kDa and a theoretical isoelectric point of 5.354. The deduced amino acid sequence of AiGSTσ contained a GST_N domain and a GST_C domain, and exhibited high similarity with other reported sigma class GSTs. In the phylogenetic tree, AiGSTσ was located in the sigma class GSTs sub-branch. The AiGSTσ mRNA transcripts were constitutively expressed in the tissues of hemocytes, muscle, mantle, gill, hepatopancreas and gonad, with the highest expression level in hemocytes, and the mRNA expression levels of AiGSTσ were significantly up-regulated in hemocytes after various pathogen associated molecular patterns (PAMPs) stimulation. The purified recombinant AiGSTσ protein exhibited catalytic activity against the common substrate 1-chloro-2, 4-dinitrobenzene (CDNB) with low thermal stability and narrow optimum pH spectrum. All these results indicated that AiGSTσ was a fragile but efficient antioxidant enzyme and was potentially involved in the innate immune responses of scallop.

Expression of G Proteins in the Eyes and Parietovisceral Ganglion of the Bay Scallop Argopecten irradians.

A multitude of image-forming eyes are spread across the bodies of certain invertebrates. Recent efforts have characterized how these eyes function, but less progress has been made toward describing the neural structures associated with them. Scallops, for example, have a distributed visual system that includes dozens of eyes whose optic nerves project to the lateral lobes of the parietovisceral ganglion (PVG). To identify sensory receptors and chemical synapses associated with the scallop visual system, we studied the expression of four G protein α subunits (Gαi, Gαo, Gαq, and Gαs) in the eyes and PVG of the bay scallop Argopecten irradians (Lamarck, 1819). In the eyes of A. irradians, we noted expression of Gαo by the ciliary photoreceptors of the distal retina, expression of Gαq by the rhabdomeric photoreceptors of the proximal retina, and the expression of Gαo and Gαq by the cells of the cornea; we did not, however, detect expression of Gαi or Gαs in the eyes. In the PVG of A. irradians, we noted widespread expression of Gαi, Gαo, and Gαq. The expression of Gαs was limited to fine neurites in the lateral and ventral central lobes, as well as large unipolar neurons in the dorsal central lobes. Our findings suggest that light detection by the eyes of A. irradians is conferred primarily by photoreceptors that express Gαo or Gαq, that the corneal cells of scallops may contain sensory receptors and/or receive neural input, and that G protein labeling is useful for visualizing substructures and identifying specific populations of cells within the nervous systems of invertebrates.

Polymorphism in a serine protease inhibitor gene and its association with the resistance of bay scallop (Argopecten irradians) to Listonella anguillarum challenge

Serine protease inhibitors (SPIs) play a crucial role in regulation of both host and bacterial serine protease. They are classified into several protein families, where Kazal-type inhibitors are one of families with multi-domain. In the present study, the polymorphism of AiSPI from Bay scallop Argopecten irradians was found to be associated with disease resistance of bay scallop against Listonella anguillarum. Nine single nucleotide polymorphisms (SNPs) were identified in the exon region of AiSPI, where five SNPs were non-synonymous mutation. Three of these mutations were located in “kazal-like 3”domain, two SNP loci positioned at +536, +1312 were selected for further association studies. For the locus +536, the genotype frequency of A/G in the resistant stock (12.8%) was significantly lower (p < 0.05) than that in the susceptible stock (35.1%), while, the genotype A/A in the resistant stock (87.2%) was significantly higher in comparison with susceptible stock (64.9%) (p < 0.05). The G allele frequencies were 6.4% and 17.6% in resistant stock and susceptible stock, respectively, and χ2-test revealed a significant difference in the frequency distribution between the two stocks (p < 0.05). But there was no significant association between the mutation C-T at locus +1312 with either resistant or susceptible group (p > 0.05). The genotype frequencies of T/T, T/C, C/C at locus +1312 were 94.6%, 2.7% and 2.7% respectively in the susceptible stock, while 100%, 0% and 0% respectively in the resistant stock. The amino acid change for the mutation at locus +536 A-G was from asparagine to serine, and the predicted homology model of this amino acid variation could affect its function as well as the structural integrity of the domain. In vitro elastase inhibition assay of the protein variants at locus +536 was conducted to explicate the effect of SNP. The increasing concentration of protein (0 mmol/L– 2.93 mmol/L) was incubated with 80 nmol/L elastase where the residual enzyme activity values for rAiSPI (N) with A variant and rAiSPI (S) with G variant were started to reduce from 0.40 to 0.215 and 0.435 to 0.356, respectively. The elastase inhibition ability of rAiSPI (N) variant was significantly higher than that of rAiSPI (S) (p < 0.01). The results suggested that the mutation at locus +536A/A significantly associated with disease resistance of bay scallop would shed light for selective breeding program.

Immune response of the bay scallop, Argopecten irradians, after exposure to the algicide palmitoleic acid

Palmitoleic acid (PA) is an effective algicide against the toxin-producing dinoflagellate Alexandrium tamarense; however, its effects on the immune system of the edible bay scallop Argopecten irradians are unclear. Therefore, we investigated the effects of PA on the immune response in A. irradians by assessing total haemocyte counts (THC), alkaline phosphatase activity (ALP), nitrite oxide (NO), glutathione (GSH), and lactate dehydrogenase (LDH) levels, as well as the expression of immune-related genes (FREP, PGRP, HSP90, MnSOD, and Cu/ZnSOD) at various hours post-exposure (hpe) to the compound. THC decreased in PA-treated groups, whereas ALP increased significantly in all of the PA treatment groups at 3 hpe, after which it significantly decreased. The LDH and NO levels were significantly enhanced in the high and medium concentration group. Notably, the GSH level increased in all PA treatment groups at each time interval. Our study revealed that after treatment with different concentrations of PA, variable effects on the expression of genes involved in the immune system response were observed. The results of our study demonstrate that immersing scallops in PA at effective concentrations could result in differential effects on immune system responses and expression of immune-related genes. Specifically, PA may disrupt the endocrine system or affect signal transduction pathways in the scallops. Therefore, the present study highlights the potential risk of using the PA as an algicide to control algal bloom outbreaks in the marine environment.