Optimisation and Characterisation of the Protein Hydrolysate of Scallops (Argopecten purpuratus) Visceral By-Products.

In this research, scallops (Argopecten purpuratus) visceral meal (SVM) and defatted meal (SVMD) were analysed for their proximal composition, protein solubility, and amino acid profile. Hydrolysed proteins isolated from the scallop's viscera (SPH) were optimised and characterised using response surface methodology with a Box-Behnken design. The effects of three independent variables were examined: temperature (30-70 °C), time (40-80 min), and enzyme concentration (0.1-0.5 AU/g protein) on the degree of hydrolysis (DH %) as a response variable. The optimised protein hydrolysates were analysed for their proximal composition, yield, DH %, protein solubility, amino acid composition, and molecular profile. This research showed that defatted and isolation protein stages are not necessaries to obtain the hydrolysate protein. The conditions of the optimization process were 57 °C, 62 min and 0.38 AU/g protein. The amino acid composition showed a balanced profile since it conforms to the Food and Agriculture Organisation/World Health Organisation recommendations for healthy nutrition. The predominant amino acids were aspartic acid + asparagine, glutamic acid + Glutamate, Glycine, and Arginine. The protein hydrolysates' yield and DH % were higher than 90% and close to 20%, respectively, with molecular weight between 1-5 kDa. The results indicate that the protein hydrolysates of scallops (Argopecten purpuratus) visceral by product optimised and characterised was suitable a lab-scale. Further research is necessary to study the bioactivity properties with biologic activity of these hydrolysates.

Beach strandings of Tehuelche scallop, Aequipecten tehuelchus, in Patagonia: Multi-scale processes and management implications.

The magnitude and causal mechanisms of a massive beach stranding of Tehuelche scallops that occurred in November 2017 in San José Gulf, Argentina, were investigated with the long-term goal of improving the assessment and management of the scallop fishery. The biomass of scallops washed ashore and deposited over a 10-km stretch of coast was estimated by quadrat sampling and compared with the results of a scallop stock assessment survey conducted three months prior to the stranding event. The resulting estimate of total biomass loss was in the order of 200 t, representing 10% of the estimated total scallop biomass in the San José gulf. The stranding coincided with persistent strong southerly winds (13 m/s) blowing for 24 h in San José Gulf, and large-scale windstorms that affected the southern tip of South America. Surface waves predicted under such windstorm conditions could generate strong bottom orbital velocities at shallow waters (<10 m depth), sufficient to drag and transport ashore scallops by Stokes drift (600-2000 m in 24 h). Analysis of local wind data recorded over a 6.8-year period indicated that such windstorm conditions occurred with an average frequency of 7.7 times per year, implying that beach strandings could have a significant impact on the scallop resource and its fishery. The actual impact of windstorms would depend on the location, depth and size composition of scallop beds, shallow beds (<10 m depth) being more susceptible to stranding risks. The use of spatial harvest control rules, instead of the global total allowable catch used at present, could reduce the risks of yield loss by directing the harvest to the more vulnerable scallop beds.

Assessment of the Presence of Lipophilic Phycotoxins in Scallops (Argopecten purpuratus) Farmed along Peruvian Coastal Waters.

ABSTRACT: 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.

Molecular characterization and protein localization of the antimicrobial peptide big defensin from the scallop Argopecten purpuratus after Vibrio splendidus challenge.

Big defensins are antimicrobial peptides (AMPs) that are proposed as important effectors of the immune response in mollusks, chelicerates and chordates. At present, only two members of the big defensin family have been identified in scallop. In the present work, a cDNA sequence encoding a new big defensin homologue was characterized from the scallop Argopecten purpuratus, namely ApBD1. ApBD1 cDNA sequence comprised 585 nucleotides, with an open reading frame of 375 bp and 5'- and 3'-UTRs of 41 and 167 bp, respectively. The deduced protein sequence contains 124 amino acids with a molecular weight of 13.5 kDa, showing characteristic motifs of the big defensin family and presenting 76% identity with the big defensin from the scallop A. irradians. Phylogenetic analysis revealed that ApBD1 is included into the cluster of big defensins from mollusks. Tissue-specific transcript expression analysis by RT-qPCR showed that ApBD1 was present in all tissues tested from non-immune challenged scallops but it was most strongly expressed in the mantle. The transcript levels of ApBD1 were significantly up-regulated in gills at 24 and 48 h post-injection with the heat-attenuated bacteria Vibrio splendidus. Additionally, immunofluorescence analysis using a polyclonal anti-ApBD1 antibody showed that this protein was abundantly located in epithelial linings of gills and mantle; and also in digestive gland showing ApBD1-infiltrating hemocytes from immune challenged scallops. This is the first time that a big defensin is detected and located at the protein level in a mollusk. These results suggest an important role of ApBD1 in the mucosal immune response of A. purpuratus.

Exposure to phenanthrene and depuration: Changes on gene transcription, enzymatic activity and lipid peroxidation in gill of scallops Nodipecten nodosus.

Understanding the mechanism of phenanthrene (PHE) biotransformation and related cellular responses in bivalves can be an important tool to elucidate the risks of polycyclic aromatic hydrocarbons (PAHs) to aquatic organisms. In the present study it was analyzed the transcriptional levels of 13 biotransformation genes related to cytochrome P450 (CYP), glutathione S-transferase (GST), sulfotransferase (SULT), flavin-containing monooxygenase and fatty acid-binding proteins by qPCR in gill of scallops Nodipecten nodosus exposed for 24 or 96h to 50 or 200µgL(-1) PHE (equivalent to 0.28 and 1.12µM, respectively), followed by depuration in clean water for 96h (DEP). Likewise, it was quantified the activity of catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD), glutathione reductase (GR), glucose 6-phosphate dehydrogenase (G6PDH), GST and levels of lipid peroxidation. Increased transcriptional levels of CYP2UI-like, CYP2D20-like, CYP3A11-like, GSTomega-like, SULT1B1-like genes were detected in organisms exposed to PHE for 24 or 96h. In parallel, GR and GPX activities increased after 96h exposure to 200µgL(-1) PHE and G6PDH activity increased after 24h exposure to 50µgL(-1) PHE. This enhancement of antioxidant and phase I and II biotransformation systems may be related to the 2.7 and 12.5 fold increases in PHE bioaccumulation after 96h exposure to 50 and 200µgL(-1) PHE, respectively. Interestingly, DEP caused reestablishment of GPX and GR activity, as well as to the transcript levels of all upregulated biotransformation genes (except for SULT1B1-like). Bioaccumulated PHE levels decreased 2.5-2.9 fold after depuration, although some biochemical and molecular modifications were still present. Lipid peroxidation levels remained lower in animals exposed to 200µgL(-1) PHE for 24h and DEP. These data indicate that N. nodosus is able to induce an antioxidant and biotransformation-related response to PHE exposure, counteracting its toxicity, and DEP can be an effective protocol for bivalve depuration after PHE exposure.

Análise bacteriológica de músculo e gônadas de vieira, Nodipecten nodosus (Mollusca: Bivalvia), congelados e irradiados / Bacteriological analysis of frozen and irradiated scallops muscle and gonads Nodipecten nodosus (Mollusca: Bivalvia)

No presente trabalho foram analisadas amostras de músculo e gônadas de vieira crus e congelados, oriunda de maricultura de Angra dos Reis, Rio de Janeiro, Brasil. Esta pesquisa teve como finalidade a verificação da eficiência da irradiação, utilizando-se doses de 2kGy e 5kGy. Na Contagem de Bactérias Heterotróficas Aeróbias Mesófilas (CBHAM) observou-se diferença estatisticamente significativa do grupo controle em relação ao grupo irradiado a 5kGy; enquanto que para a Contagem de Bactérias Heterotróficas Aeróbias Psicrotróficas (CBHAP) não se observou nenhuma diferença estatisticamente significativa entre os grupos avaliados. O Número Mais Provável (NMP) de Enterococcus spp. não teve sua presença evidenciada em nenhuma das amostras analisadas. Conclui-se que a irradiação, nesta pesquisa, foi eficiente somente para bactérias mesófilas na dose de 5kGy.(AU)

The present article investigated the effectiveness of irradiation process to conservate frozen raw scallops muscle and gonads. Samples of this animal were collected from cultivated areas at Angra dos Reis, Rio de Janeiro state, Brazil. The samples were submitted to treatment of 2 and 5 kGy doses. Mesophilic Aerobic Heterotrophic Bacteria Count showed a statistically significant difference from the control group related to the 5kGy one, while for the Heterotrophic Bacteria Aerobic Psychrotrophic Count were not observed any statistically significant difference among the analysed groups. The Most Probable Number of Enterococcus spp. was not evident in any of the samples. It was concluded that irradiation was effective only for mesophilic bacteria using the 5kGy dose in this research.(AU)

Análise bacteriológica de músculo e gônadas de vieira, Nodipecten nodosus (Mollusca: Bivalvia), congelados e irradiados / Bacteriological analysis of frozen and irradiated scallops’ muscle and gonads Nodipecten nodosus (Mollusca: Bivalvia)

No presente trabalho foram analisadas amostras de músculo e gônadas de vieira crus e congelados, oriunda de maricultura de Angra dos Reis, Rio de Janeiro, Brasil. Esta pesquisa teve como finalidade a verificação da eficiência da irradiação, utilizando-se doses de 2kGy e 5kGy. Na Contagem de Bactérias Heterotróficas Aeróbias Mesófilas (CBHAM) observou-se diferença estatisticamente significativa do grupo controle em relação ao grupo irradiado a 5kGy; enquanto que para a Contagem de Bactérias Heterotróficas Aeróbias Psicrotróficas (CBHAP) não se observou nenhuma diferença estatisticamente significativa entre os grupos avaliados. O Número Mais Provável (NMP) de Enterococcus spp. não teve sua presença evidenciada em nenhuma das amostras analisadas. Conclui-se que a irradiação, nesta pesquisa, foi eficiente somente para bactérias mesófilas na dose de 5kGy.

The present article investigated the effectiveness of irradiation process to conservate frozen raw scallops’ muscle and gonads. Samples of this animal were collected from cultivated areas at Angra dos Reis, Rio de Janeiro state, Brazil. The samples were submitted to treatment of 2 and 5 kGy doses. Mesophilic Aerobic Heterotrophic Bacteria Count showed a statistically significant difference from the control group related to the 5kGy one, while for the Heterotrophic Bacteria Aerobic Psychrotrophic Count were not observed any statistically significant difference among the analysed groups. The Most Probable Number of Enterococcus spp. was not evident in any of the samples. It was concluded that irradiation was effective only for mesophilic bacteria using the 5kGy dose in this research.

El ostión del norte chileno (argopecten purpuratus), un alimento de alto valor nutricional / The scallop from the chilean north (argopecten purpuratus), a food with a high nutritional value

Mollusks are good food and also products of great commercial value. However, information about the nutritional value of these shellfish as foods is scarce. This work focused on the chemical characterization of scallops, one of the main products of the Chilean aquaculture. Samples of frozen scallops from three culture centers located in the north of Chile (Coquimbo Region) were subjected to several chemical analysis to obtain information about their nutritional composition. Results show that per serving (approximately 100 g) scallops provide low fat, but containing an interesting amount of omega-3 fatty acids (EPA and DHA). Carbohydrate and cholesterol content are also low. Phytosterol content of scallops comprises 30 percent of the total sterols, presumable derived from their feeding. Scallops are also a good supply of tryptophan, vitamin B12 and minerals. For these reasons scallops are very good nutritional food.

Los moluscos, además de constituir un alimento, son productos de gran valor comercial. Sin embargo, es poco es lo que se hecho para valorizar desde el punto de vista nutricional a estos mariscos como alimentos. Este trabajo desarrolla la caracterización de la composición química del ostión, uno de los principales mariscos de la acuicultura chilena. Muestras de ostión congeladas provenientes de tres centros de cultivo del norte chileno (Región de Coquimbo) se sometieron a diferentes análisis con la finalidad de conocer su composición química. Los análisis muestran que una porción de ostiones (100 g aproximadamente) aporta poca grasa, pero contiene una interesante cantidad de ácidos grasos omega-3 (EPA y DHA), además presenta un bajo contenido de carbohidratos y de colesterol. Un aspecto novedoso es el contenido de fitoesteroles de los ostiones, derivado de su alimentación, los que son en promedio el 30 por ciento del contenido total de esteroles. El ostión, además, constituye un buen aporte de triptófano, de vitamina B12 (cobalamina) y de sales minerales. Por este motivo el consumo del ostión, además de ser placentero, es un muy buen alimento.

The sensorial structures of Spondylus americanus Hermann,1781 (Mollusca: Bivalvia, Spondylidae)

Adult animals of Spondylus americanus were analyzed and specialized sensorial structures, the sensorial papillae and the eyes, were characterized. The sensorial papillae were projections on the edge of the mantle in form of light brown fingers which had function of percepting stimulus coming from the medium. They were constituted by loose conjunctive tissues with longitudinal muscular fibers and externally covered by ciliated cubic epithelium, which presented high amount of melanocytes that gave the coloration of the papillae. The eyes were more complex, being on small stalks histologically similar to the papillae. They exhibited a circular formate and had a metallic blue color. Theses structures were constituted by a corneo epithelium, cornea, lens, retina, basal stalk, periocular band and optical nerve. The eyes were distributed asymmetrically to both valves related with the sedentarism of the species. Right valve presented a smaller number of eyes when compared to left one.

Foram examinados exemplares adultos de Spondylus. americanus Hermann, 1781 e estruturas especializadas na percepção de estímulos foram caracterizadas: as papilas sensoriais e os ocelos. As papilas sensoriais são projeções do bordo manto em forma de dedos de cor castanha e com a função de perceber estímulos vindo do meio, são constituídas por tecido conjuntivo frouxo contendo fibras musculares longitudinais e revestidas externamente por epitélio cúbico ciliado, o qual apresenta grande quantidade de melanócitos, que dão a coloração das papilas. Os ocelos são mais complexos, estando sobre pequenos pedúnculos histologicamente semelhante às papilas, têm formato circular e possui cor azul metálica. Constituí-se por um epitélio córneo, córnea, lente, retina, pedúnculo basal, banda periocular e nervo óptico. Os ocelos distribuem-se assimetricamente por ambas as valvas, o que está relacionado com o sedentarismo da espécie. A valva direita apresenta menor número de ocelos quando comparada a esquerda.