Scallop Mantle Research Articles

Scallop mantle extract inhibits insulin signaling in HepG2 cells.

Scallops are important marine products in Hokkaido, Japan. Not only scallop adductor muscle but also mantle is often eaten at sashimi or smoking in Japan. We showed previously that feeding the scallop mantle epithelial cell layer causes an increase in serum glucose concentration and the death of rats. To clarify the mechanism of glucose metabolism disorder by mantle epithelial cell layer, we investigated whether extracts from mantle tissue (mantle extract) induce insulin resistance using HepG2 cells. Mantle extract suppressed insulin‐stimulated phosphorylation of Akt, key protein which is involved in insulin signaling. In addition, treatment of HepG2 cells with mantle extract decreased significantly glycogen content and mRNA expression levels of glucose‐6‐phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK) involved in gluconeogenesis, suggesting that mantle extract inhibits insulin signaling. These results show that mantle extract inhibits insulin signaling in HepG2 cells, suggesting that an increase in serum glucose concentration in vivo may be due to the inhibition of insulin signaling.

Characteristic antioxidant activity and comprehensive flavor compound profile of scallop (Chlamys farreri) mantle hydrolysates-ribose Maillard reaction products

The objective of the present study was to improve the utilization of scallop (Chlamys farreri) byproducts by using Maillard reaction. Scallop mantle hydrolysates (SMHs) were prepared using neutrase then reacted with ribose. Thirty-four peptides were identified from SMHs by UPLC-Q-TOF-MS, and the abundance of Asp and Lys suggested the strong Maillard reactivity. The formation of Schiff’s base as well as modification of amide I, II and III bands in Maillard reaction products (MRPs) was confirmed by ultraviolet–visible, fluorescence, and Fourier transform infrared spectroscopy. Thirty volatile compounds were produced by the reaction of SMHs with ribose. Moreover, MRPs with enhanced radical scavenging and anti-linoleic acid peroxidation activities over SMHs promoted the survival and reduced the DNA damage of HepG2 cells treated with hydrogen peroxide. These results suggest that SMHs-ribose MRPs can be potentially used as food antioxidant for suppressing of lipid oxidation or protecting of cell from oxidative damage.

Feeding of scallop mantle epithelial cell layer causes subacute toxicity against rodents

Japanese scallops Patinopecten yessoensis are one of the main marine products of Hokkaido, Japan. In addition to adductor muscle, scallop mantle tissue is also eaten in Japan. We fed Wistar rats diets containing the scallop mantle epithelial cell layer for 3–8 weeks and compared the outcomes with a control group. No differences in general appearance or behavior were observed between the groups for the first 2 weeks. Thereafter, a significant decrease in food consumption was observed, and the treated rats died between 6 and 8 weeks. Serum biochemistry and histological studies revealed nephrotoxicity and hepatotoxicity in rats fed scallop mantle epithelial cells. Glucose tolerance tests showed that feeding scallop mantle epithelial cells to rats causes a glucose metabolism disorder. A diet containing a water extract from scallop mantle epithelial cells caused toxicity in mice, but a diet containing a methanol extract, which dissolves diarrhetic shellfish poisoning (DSP) toxin, or an extract in heated 0.1 M HCl, which dissolves paralytic shellfish poisoning (PSP) toxin, did not cause toxicity. Mice fed a diet containing pronase-treated water extract neither showed a decrease in their food intake nor death. These results suggest that a water-soluble component other than DSP or PSP toxin causes toxicity.

Scallop genome provides insights into evolution of bilaterian karyotype and development

Reconstructing the genomes of bilaterian ancestors is central to our understanding of animal evolution, where knowledge from ancient and/or slow-evolving bilaterian lineages is critical. Here we report a high-quality, chromosome-anchored reference genome for the scallop Patinopecten yessoensis, a bivalve mollusc that has a slow-evolving genome with many ancestral features. Chromosome-based macrosynteny analysis reveals a striking correspondence between the 19 scallop chromosomes and the 17 presumed ancestral bilaterian linkage groups at a level of conservation previously unseen, suggesting that the scallop may have a karyotype close to that of the bilaterian ancestor. Scallop Hox gene expression follows a new mode of subcluster temporal co-linearity that is possibly ancestral and may provide great potential in supporting diverse bilaterian body plans. Transcriptome analysis of scallop mantle eyes finds unexpected diversity in phototransduction cascades and a potentially ancient Pax2/5/8-dependent pathway for noncephalic eyes. The outstanding preservation of ancestral karyotype and developmental control makes the scallop genome a valuable resource for understanding early bilaterian evolution and biology.

Angiotensin Converting Enzyme Inhibitory, Antioxidant Activities, and Antihyperlipidaemic Activities of Protein Hydrolysates From Scallop Mantle (Chlamys Farreri)

Scallop mantle (Chlamys Farreri) was hydrolysed with commercially available food-grade mixed proteases. The resulting hydrolysates of scallop protein hydrolyzate contained high levels of Glu, Gly, Asp, Arg, Ala, and Pro, and showed DPPH, hydroxyl radicals scavenging abilities, and reducing power. In this study scallop protein hydrolyzate had angiotensin converting enzyme inhibitory activity in vitro with an IC50 of 10.28 mg/ml. It was also found that oral administration of scallop protein hydrolyzate decreased total serum cholesterol and triglyceride, and increased high-density lipoprotein cholesterol in rats fed with high-fat diet. The above results indicate that scallop protein hydrolyzate may prove to be a promising functional agent for the prevention and treatment of hypertension, hyperlipidaemia, and other cardiovascular diseases.

Characterization of the Zhikong Scallop (Chlamys farreri) Mantle Transcriptome and Identification of Biomineralization-Related Genes

Chlamys farreri is a significant species in aquaculture and fishery in East Asia. A deep understanding of its shell formation by studying the transcriptome of the mantle, a key organ in shell formation, could provide important guidance for its culture. Thus, we sequenced and analyzed the mantle transcriptome of C. farreri. The 77,975 unigenes were generated after Illumina sequencing and de novo assembly. The unigenes were annotated using authoritative databases (non-redundant (NR), COG, Gene Ontology (GO), and KEGG) to obtain functional information. BLASTX alignment was performed between unigenes and reported proteins related to biomineralization. The results identified 53 homologous genes representing 17 matrix proteins, most of which are involved in calcite formation, and 171 homologies with 26 proteins related to general processes of biomineralization. The discovery and unusually high expression of MSP-1 suggested its importance in scallops. Homologous unigenes with aragonite-formation-related matrix proteins were much fewer compared with those related to calcite formation. The results implied that, in C. farreri, the number and proportion of matrix proteins related to aragonite formation is much lower than those related to calcite formation, which was consistent with the proportions of aragonite and calcite in C. farreri shells. Thus, the formation of different polymorphs of calcium carbonate (calcite and aragonite) in molluskan shells is regulated by different groups of proteins. Moreover, 17 candidate unigenes, which are probably involved in biomineralization, were predicted by screening for gene products with secreted domains and tandem-arranged repeat units. Our results contribute to the understanding of biomineralization processes and the evolution of shell formation.

Properties of scallop mantle collagen: its content, tissue distribution and thermal behavior

To obtain fundamental information for the effective use of scallop Patinopecten yessoensis mantle, which is one of the underutilized marine resources. Some properties of collagen contained in the mantle were examined by chemical and histochemical techniques. Collagen content in the mantle varied annually, ranging from 0.98 to 1.72% of wet tissue, 7.7 to 12.6% of dry tissue and 13.5 to 26.5% of total protein, being relatively in high level of collagen content of invertebrate muscles. Collagen fiber was densely distributed in the inner connective tissue matrix of the mantle pallial, in contrast to the inner fold part which was rich in muscle fibers. The collagen contained in the crude collagen fraction (residue after alkali extraction), prepared from the mantle, was revealed to have considerably low solubility on hot-water extraction, constantly less than 20% of the total collagen at the temperatures in the range of 20–90°C.

Characterization of molecular species of collagen in scallop mantle

Pepsin-solubilized collagen (SMPC) extracted from scallop mantle was first subjected to amino acid analysis and molecular weight determination. The SMPC was rich in hydroxylysine. After salting out, the SMPC showed two different profiles in molecules, amino acids and peptide maps. The two different collagen molecules had different uronic acid contents and gel-forming abilities. SMPC may be applicable to a variety of usage, including functional foods.

Identification of a novel unconventional myosin from scallop mantle tissue.

We isolated a cDNA encoding a novel unconventional myosin from scallop mantle tissue (scallop unconventional myosin: ScunM) and determined the nucleotide sequence. It comprises 2,739 bp with 5' and 3'-noncoding sequences and has an open reading frame of 2,334 bp that encodes 778 amino acids. While ScunM has a motor domain and a short tail domain without having light chain-binding IQ motifs like myosin XIV, the deduced amino acid sequence exhibits low homology, 30-36%, to known myosins. Phylogenetic analysis of the motor domain suggested that ScunM belongs to a novel unconventional myosin class. ScunM has an insertion of 67 amino acids in the putative actin-binding site (loop2 site). Western blot analysis with an antibody produced against the N-terminal region revealed that ScunM was strongly expressed in the mantle and mantle pallial cell layer of scallop.

Mechanical Injury of Scallop (Patinopecfen ryessonsis Jay) Mantle, Occurring with Drilling Work of Ear-Hanging Culture

Mechanical Injury of Scallop (Patinopecfen ryessonsis Jay) Mantle, Occurring with Drilling Work of Ear-Hanging Culture

A preliminary study of the behaviour and vitality of reseeded juvenile great scallops, of three sizes in three seasons

In order to have a better understanding of recessing in great scallop, Pecten maximus and consequently the causes of mortality at reseeding, this study has monitored, at different seasons, the dispersion and recessing of different sizes of juveniles (about 15, 30 and 45 mm, called ‘small’, ‘medium’ and ‘large’) after seeding. Moreover, the aim was to see when small spat (15 mm) could be seeded, and thus reduce the costs of intermediate culture. Three monitoring approaches were used together: (1) continual observations by remote video camera, of a defined area (less than 1 m2) containing 10 scallops from each size group; (2) daily monitoring of behaviour with divers along three bottom lines, with 20 × 1 m2 plots each and nine marked scallops per plot; and (3) the biochemical content of the muscle: adenylic energetic charge and storage of energy reserves (glucides, proteins, lipids). The video monitoring identified but did not quantify predator behaviour, particularly at night. The role and behaviour of spiny crab, Maia squinado, and of small predators has clearly been shown, such as: (a) small crustaceans, Inachus sp., breaking the edges of scallop valves; and (b) small gobies, Pomatoschistus pictus, pecking the tentacles of the scallop mantle. For the monitoring by divers, filtering appeared much too difficult to look at for it was very disturbed by divers, and anyway the resumption of filtering came immediately after seeding. On the other hand, diver monitoring of dispersal and recessing was quite easy to do with a minimum of practice. On the basis of dispersal, the best seasons for seeding appear to be spring or summer. In autumn, two-thirds of ‘small’ and ‘medium’ juveniles are missing 3 days after seeding, but we could not observe whether they had been eaten by predators or had just moved and recessed farther. There was no experiment in winter owing to adverse conditions for scallop seedings. Biochemical analyses confirmed the unsuitability of autumn for scallop seeding, because of very low glucide content in this season. The adenylic energetic charge in the smooth part of the muscle showed that stress before seeding (aerial exposure, handling), and post-seeding behaviour (swimming, recessing) have a high energetic cost for scallops. In summer and autumn, 3 days after seeding, none of the three size batches recovered their initial vitality.

Acrylic acid, as an antibacterial substance in scallop.

Acrylic acid was identified as an antibacterial substance in scallop. This substance was mainly distributed in the mantle of the scallop. The content of acrylic acid in the scallop mantle showed marked seasonal variation. The variation was well related with that of the abundance of Protogonyaulax spp. Acrylic acid was also detected both in the cells of Protogonyaulax spp. and their cultured medium. It could not be detected in cultured Skeletonema costatum as well as the plankton collected by net hauling in the bloom of diatom. From these, acrylic acid in the mantIe of scallop was supposed to originate from Protogonyaulaxs pp.

Observations on phagocytosis of Coccomyxa parasitica (Coccomyxaceae; Chlorococcales) in Placopecten magellanicus

Phagocytosis of Coccomyxa parasitica in Placopecten magellanicus is described. Host phagocytosis occurs throughout the infective process and can also be demonstrated experimentally using cultured algae. Agranular and granular leukocytes of various types are responsible, and the algae are highly resistant to digestion. The greatest concentration of algae occurs in the scallop's mantle region and appears to be related to the circulatory system. The indications are that C. parasitica might enter P. magellanicus via the normal feeding and digestion processes and that host phagocytosis contributes to the spread of the algal cells.

THE POLYCHAETE CERATONEREIS TRIDENTATA AS A PEST OF THE SCALLOP AEQUIPECTEN GIBBUS

The nereid polychaete Ceratonereis tridentata has been found occupying mudblisters in the calico scallop, Aequipecten gibbus, from off North Carolina. Characteristic Ceratonereis blisters were found in 24% of live scallops examined. These blisters can be distinguished easily from those of Polydora websteri by their larger size and often by their location in the scallop shell. Blister cavities may communicate with the mantle cavity or with the exterior. Anomalous malformations of the gills and the gonadal mass often accompany blisters having munication with the scallop mantle cavity. Ceratonereis tridentata is a facultative parasite of this scallop, also occurring among the epifauna of its shell.