Environmental salinity and dietary lipid nutrition strategy: Effects on flesh quality of the marine euryhaline crab Scylla paramamosain.

The quality of crustaceans' flesh has direct impact on consumers' purchase choices, with water environment and dietary nutrition being effective ways to regulate flesh quality. The aim of present study was to investigate the impacts of water salinity (low, 4 and medium, 23) and dietary lipid source (fish oil and soybean oil) on nutritional values, texture, taste and odor of flesh of mud crab. While water salinity had no significant influence on nutritional values of crab flesh, crabs fed soybean oil displayed significantly lower contents of amino acids and n-3 PUFAs in muscle. However, crabs reared at low salinity showed reduced flesh hardness, chewiness and gumminess likely related to altered myofiber structure, that impacted muscle texture. Furthermore, low salinity and dietary soybean oil weakened umami taste and aroma characteristics of crab flesh associated with decreased contents of free amino acids, flavor nucleotides, inorganic ions and odor active compounds in flesh.

Meat texture, muscle histochemistry and protein composition of Eriocheir sinensis with different size traits.

The main aim of the present work was to investigate the effect of the inherent differences in the raw muscle on the textural quality of the cooked meat from different sized Eriocheir sinensis. The content of entrapped water was 73.8-77.7 g/100 g in raw muscle. The density and diameter of muscle thick microfilaments ranged between 137 and 158/µm2 and 20.9-27.0 nm. These results demonstrated that the raw muscle from the tender group had a smaller density of larger diameter thick microfilaments and more entrapped water than other samples, which could explain the high tenderness of the cooked meat (P < 0.05). The potential structural proteins that indicated tenderness include myosin regulatory light chain 2, ancient ubiquitous protein 1, tubulin α-2 chain, and ß-catenin, was determined using liquid chromatography-tandem mass spectrometry. The inherent attributes of raw muscle could explain the textural differences of the cooked meat from Eriocheir sinensis.

Comparative iTRAQ-based quantitative proteomic analysis of the Chinese grass shrimp (Palaemonetes sinensis) infected with the isopod parasite Tachaea chinensis.

BACKGROUND: Although parasitic isopods can negatively affect the reproduction and ingestion of several commercially important crustaceans, little is known regarding the mechanisms that underlie these effects. METHODS: In the present study, the iTRAQ (isobaric tags for relative and absolute quantification) approach was applied to identify differentially expressed proteins in the Chinese grass shrimp Palaemonetes sinensis infected with the parasitic isopod Tachaea chinensis. RESULTS: On the basis of our analysis, we identified 1262 proteins from a total of 4292 peptides. There was a significant difference in the expression of 182 proteins between the control and infected groups, among which 69 were upregulated and 113 were downregulated after T. chinensis infection. The differentially expressed proteins revealed that parasitism may inhibit the immune response, thereby increasing host vulnerability to additional lethal infection. Furthermore, T. chinensis may secrete anticoagulants to inhibit hemolymph clotting. Moreover, the isopod parasite placed a heavy metabolic burden on the host, particularly with respect to glucose metabolism. CONCLUSIONS: Our study is the first to use the iTRAQ-based proteomic approach to analyze the effects of an isopod parasite on its host. The results we obtained using this approach will make a valuable contribution to understanding the molecular mechanisms underlying isopod parasitism on crustaceans.

A chiral assembly of gold nanoparticle trimer-based biosensors for ultrasensitive detection of the major allergen tropomyosin in shellfish.

A biosensor based on a chiral assembly of polymer of gold nanoparticle (AuNP) trimers was developed for the detection and quantification of the major shellfish allergen tropomyosin (TROP). TROP and anti-TROP monoclonal antibodies (mAb) were immobilized on 20 nm and 30 nm 16-mercaptohexadecanoic acid (16-MHDA) functionalized AuNPs to assemble a trimer, which has a Circular dichroism (CD) signal. The free TROP from samples was quantified as an inhibitor for the formation of the AuNP trimer. The AuNP trimer-based biosensor allowed for the selective determination of TROP in the range of 0.1-15 ng mL-1 with the limit of detection (LOD) of 21 pg mL-1 (S/N = 3) and the limit of quantitation (LOQ) of 70 pg mL-1 (S/N = 10). The use of a AuNP trimer-based biosensor with simple sample preparation functions with specificity and accuracy; this highlights its applicability for the detection of allergens in shellfish products, related products and their production lines. Furthermore, based on the less conserved sequences of TROP in phylogenetically different species, this biosensor is currently being used to identify the adulteration of shellfish products using TROP as biomarker.

Enumeração e identificação de víbrios sacarose-positivos em amostras de lulas frescas comercializadas no município de Niterói-RJ / Enumeration and identification of sucrose-positive vibrios in samples of fresh squids commercialized at Niterói county-RJ

Foi efetuado um estudo sobre a enumeração e a identificação de víbrios sacarose-positivos em lulas frescas obtidas no comércio varejista do município de Niterói-RJ. No experimento, em 50 amostras de lulas, identificadas como pertencentes à espécie Oorytheutis brasiliensis Blainville, 1823, foram isoladas Unidades Formadoras de Colônias (UFC) sacarose-positivas em 28 (56%) amostras. Destas, foram identificados o Vibrio a/ginolyticus e víbrios do grupo NAG (não aglutináveis). A média dos Números Mais Prováveis (NMP) dos víbrios totais (com exceção da amostra com NMP > 2400 bacts./g) foi 101,70 bacts./g. Do total de 29 isolamentos nas 28 amostras, o V alginolyticus do grupo I de Heiberg obteve o maior percentual (62,07%), o V alginolyticus do grupo 111 apenas 10,30% e os víbrios NAG com 27,63%.

From 50 samples of squids of lhe species Dorytheutis brasiliensis Blainville, 1823, Colonies Formed Units (CFUs) sucrose-positives Víbrio alginolyticus and NAG vibrios (non-agglutinable) were isolated. The average of the Most Probabble Number of total vibrios (except the sample with MPN > 2400 bacts./g) was 101,70 bacts./g. From 28 samples, 29 isolations were carried out and lhe V. alginolyticus group I of Heiberg's Classification showed the greatest percentage (62,07%). The V. alginolyticus group 111 showed only 10,30% and NAG vibrios 27,63%.

Enumeração e identificação de Vibrio parahaemolyticus em lulas frescas comercializadas no município de Niterói RJ Brasil / Enumeration and identification of Vibrio parahaemolyticus in fresh squids commercialized at Niterói, Rio de Janeiro State, Brazil

Com o objetivo de verificar as condições higiênico-sanitárias do pescado comercializado no município de Niterói, efetuou-se um estudo sobre a enumeração e identificação de Vibrio parahaemolyticus em lulas frescas. Foram utilizadas 50 amostras de lulas frescas, identificadas como pertencentes à espécie Oorytheutis brasiliensís Blainville, 1823. A identificação e enumeração do V. parahaemolyticus foram baseadas nos métodos descritos pela lnternational Commission on Microbiological Specifications for Foods - ICMSF (1983). A classificação de Heiberg (1936) foi utilizada como teste complementar. O V. parahaemolyticus foi identificado em três (6%) amostras, sendo que, em uma o vibrio se desenvolveu em meio com concentração salina a 10%, na prova de halofilismo. O V. parahaemolyticus apresentou os NMPs (Número Mais Provável) com média de 19,3.bactérias/g. As três amostras de V. parahaemolyticus submetidas à classificação de Heiberg apresentaram perfil compatível com o grupo VIl (Sacarose -, Manose + e Arabinose +). Concluiu-se que, mesmo sob comercialização inadequada, com manipulação e resfriamento precários, as amostras analisadas apresentaram o V. parahaemolyticus com frequências e NMPs baixos.

A study on the enumeration and identification of Vibrio parahaemolyticus in freshsquids in Niterói was undertook aiming at checking the hygienic-sanitary conditions of fish commercialized in that City. Fifty fresh squids (Oorytheutis brasiliensis, Blainville, 1823). Methods described by the lnternational Comission on Microbiological Specification for Foods-ICMSF (1983) were used to identify and enumerate V. parahaemoiyticus and Heiberg's classi-fication was a complementai test. v. parahaemoiyticus was identified in three samples (6%); in one of them it grew in an environment with 10% salt concentration during halophilism probe. Most probable number (MPN) average for V. parahaemoiyticus was 19,3 bacteria per gram. The three samples submitted to Heiberg's classification showed a profile compatible with group VIl (sacarose-, manose+, arabinose-). We concluded that, even under inadequate commercialization, manipulation and refrigeration conditions, V. parahaemolyticus frequencies and MPNs are low.