Species variation in the effects of dewatering treatment on macroalgae.

Seaweeds can be a valuable resource for biorefinery and biotechnology applications, but their high water content is a recurrent problem and one of the key bottlenecks for their sustainable use. Treatments to increase dry matter content of the kelp Laminaria digitata were recently described by the authors. However macroalgae are an extremely diverse group of organisms and compositional variation between species may influence the effects of particular treatments. In this study, potential dewatering treatments including drying, osmotic media, and the application of both organic and mineral acids all followed by screw-pressing have been tested on two other species of kelp (Laminaria hyperborea and Saccharina latissima) and a red seaweed (Palmaria palmata). Conditions that dewatered these species were identified and the data have been combined with the previous results for L. digitata. There were significant differences between species across all the traits of interest. However dewatering was highly dependent on specific interactions with both treatment and season of collection. Nevertheless, the dry matter content of brown seaweeds was widely and successfully increased by air drying or acid treatment followed by screw-pressing. The results for P. palmata were quite different, particularly with regard to juice production. For this species, acid treatment did not result in dewatering, but dry matter content could be increased by screw-pressing immediately after harvest. Together the data presented here demonstrate that dewatering pre-treatments need to be specific for the type of seaweed to be processed; important knowledge for the future use of this sustainable biomass resource.

Effect of season on the chemical composition and nutritional quality of the edible crab Cancer pagurus.

Cancer pagurus is most appreciated in southern Europe for its muscle and brown meat content. In Portugal, consumption occurs mostly in summer and at Christmas. In this study the seasonal nutritional quality of edible tissues of female and male C. pagurus was determined. Tissue composition was affected by season and sex. All tissues had a well-balanced essential amino acid composition. Muscle and gonads of females had n-3/n-6 ratios in the range of the usual recommended values, and all tissues had PUFA/SFA above the recommended level. Autumn was the season with the highest brown meat yield, total essential amino acids (muscle), taurine (all tissues), EPA (male gonads), and n-3/n-6 ratio (gonads). However, it was also the season with the highest fat content and cholesterol concentration in ovaries. Therefore, people with restricted diets should moderate the consumption of ovaries in autumn. The remaining tissues pose no risks with respect to their proximate chemical composition.

Influence of season and sex on the contents of minerals and trace elements in brown crab (Cancer pagurus, Linnaeus, 1758).

Cancer pagurus is much appreciated in Southern Europe, where the muscle, hepatopancreas, and gonads are consumed regularly with peaks in summer and December. The elemental contents of C. pagurus edible tissues were analyzed in this study during the four seasons. Results indicate that the content varied with tissue, season, and sex. The hepatopancreas had more S, Cl, Ca, Br, Sr, Fe, Cu, Cd, and Pb, the gonads had a higher concentration of Na, and the muscle was richer in Zn. Autumn and winter corresponded to a high Mg, S, Cl, K, Ca, Fe, and Zn content in both the muscle and hepatopancreas. Female gonads had more Fe, Zn, As, and Se than males but less Ca, Cl, Br, and Sr. Regarding toxic elements for human consumption, the levels of As, Hg, and Pb found in all edible tissues pose minimal risks to consumers. However, Cd concentration in the hepatopancreas was always above the action limit. Therefore, we recommend moderate hepatopancreas consumption.

Nutritional quality of the edible tissues of European lobster Homarus gammarus and American lobster Homarus americanus.

The clawed lobsters Homarus gammarus and Homarus americanus are high-priced and appreciated food items in southern Europe. From a nutritional point of view there is still limited information on the chemical composition of edible tissues (muscle, hepatopancreas, and gonads) of both species. Therefore, the aims of the present work were to study the proximate chemical composition, energy, fatty acid and amino acid profiles, and cholesterol content in each edible tissue of both species and to evaluate their nutritional quality. Differences were observed between tissues, sexes, and species. Muscle and gonads were rich in protein, whereas hepatopancreas had high fat, cholesterol, and energy contents. All edible tissues were valuable sources of essential amino acids. Contrary to the common belief that shellfish consumption should be reduced in a low-fat and -cholesterol diet, all edible tissues of clawed lobsters have a nutritious value perfectly compatible with nutritious and healthy diets.

Accumulation of elements (S, As, Br, Sr, Cd, Hg, Pb) in two populations of Cancer pagurus: ecological implications to human consumption.

The brown crab Cancer pagurus is highly appreciated in Southern European countries and edible tissues are consumed separately or as mixtures. This species is mostly harvested along the Scottish Coast and English Channel and has different market prices depending on the catching area and sex. The aim of this study was to quantify and characterize the contents of S, As, Br, Sr, Cd, Hg and Pb in muscle, hepatopancreas, gonads and gills of female and male crabs from both catching areas. Additionally, the accumulation patterns were evaluated according to hazards for human consumption and from an ecological point of view. Crabs caught off the Scottish Coast had more S and As (gonads), while specimens from the English Channel showed more Cd (gonads) and Br (gonads, muscle). The elemental bioavailability and physiological needs likely explain these differences. Independently of catching area and sex, brown crabs' muscle and gonads are safe food items as far as contaminants are concerned. Yet, Cd in hepatopancreas was always above the level set by international regulating organizations. Consequently, future risk assessment studies should evaluate Cd concentration in all edible tissues of crustaceans prior to the extensive use of processed tissues in food products.

Recombinant single-chain variable fragment and single domain antibody piezoimmunosensors for detection of HIV1 virion infectivity factor.

In this paper recombinant single-chain fragments (scFv-4BL), and single domain antibodies (4BL-V(H)) and (4BL-V(H)D) generated against HIV1 virion infectivity factor (Vif) are used to develop piezoimmunosensors for HIV1 recognition. Mixed self assembled monolayers were generated at the surface of gold coated crystal sensors to which scFv-4BL, 4BL-V(H), or 4BL-V(H)D were immobilized. Impedance analysis was used to discriminate interfering signals from frequency variation data and to increase the sensor sensitivity. The elimination of interfering signals enabled the quantification of the amount of immobilized protein and gave some indication on the viscoelasticity of immobilized biofilms. All the modified sensors were able to specifically recognize HIV1 Vif in liquid samples. The results indicate that lower sensitivities are obtained with 4BL-V(H) single domain antibodies, possibly due to its higher hydrophobic character. The sensitivity obtained when using scFv-4BL was reestablished when using the more hydrophilic 4BL-V(H)D single domain. 4BL-V(H)D piezoimunosensors were effective in recognizing HIV1 Vif from protein mixtures and from cell extracts of human embryonic kidney cells expressing HIV1 Vif. The results presented in this paper demonstrate the potential applicability of the developed piezoimmunosensors to monitor HIV1 infection evolution.