Odete Cordeiro

Changes in the soluble bone proteome of reared white seabream (Diplodus sargus) with skeletal deformities.

One of the main constrains for commercial aquaculture production of white seabream (Diplodus sargus) is the high incidence of skeletal malformations in reared fish. The purpose of this study was to obtain a better understanding of the mechanisms involved in the development of these types of skeletal malformations by comparative proteomic analysis of the vertebral column of normal and deformed fish using 2DE for protein separation and MS for protein identification. We observed a 3.2 and 3.4-fold increase in the expression of two tropomyosin isoforms, one of which (tropomyosin-4) is essential for the motility and polarization cycles of osteoclasts. Furthermore, a 1.6, 1.7 and 1.8-fold increase in three parvalbumin spots was detected, suggesting a cellular response to increased intracellular Ca²(+) levels. These results can be interpreted as signs of increased cellular activity in the bone of white seabream with skeletal deformities coupled to a higher degree of calcium mobilization, which elicits further studies into the use of these proteins as indicators of skeletal metabolic state.

Dietary tools to modulate glycogen storage in gilthead seabream muscle: glycerol supplementation.

The quality and shelf life of fish meat products depend on the skeletal muscles energetic state at slaughter, as meat decomposition processes can be exacerbated by energy depletion. In this study, we tested dietary glycerol as a way of replenishing muscle glycogen reserves of farmed gilthead seabream. Two diets were tested in duplicate (n = 42/tank). Results show 5% inclusion of crude glycerol in gilthead seabream diets induces increased muscle glycogen, ATP levels and firmness, with no deleterious effects in terms of growth, proximate composition, fatty acid profile, oxidative state, and organoleptic properties (aroma and color). Proteomic analysis showed a low impact of glycerol-supplementation on muscle metabolism, with most changes probably reflecting increased stress coping capacity in glycerol-fed fish. This suggests inclusion of crude glycerol in gilthead seabream diets (particularly in the finishing phase) seems like a viable strategy to increase glycogen deposition in muscle without negatively impacting fish welfare and quality.

Identification of Proteins with Potential Osteogenic Activity Present in the Water-Soluble Matrix Proteins from Crassostrea gigas Nacre Using a Proteomic Approach

Nacre, when implanted in vivo in bones of dogs, sheep, mice, and humans, induces a biological response that includes integration and osteogenic activity on the host tissue that seems to be activated by a set of proteins present in the nacre water-soluble matrix (WSM). We describe here an experimental approach that can accurately identify the proteins present in the WSM of shell mollusk nacre. Four proteins (three gigasin-2 isoforms and a cystatin A2) were for the first time identified in WSM of Crassostrea gigas nacre using 2DE and LC-MS/MS for protein identification. These proteins are thought to be involved in bone remodeling processes and could be responsible for the biocompatibility shown between bone and nacre grafts. These results represent a contribution to the study of shell biomineralization process and opens new perspectives for the development of new nacre biomaterials for orthopedic applications.

Teleost fish osteocalcin 1 and 2 share the ability to bind the calcium mineral phase.

The occurrence of a second osteocalcin (OC2) has been reported in teleost fish, where it coexists with OC1 in some species. While it has been proposed that OC2 gene originated from OC1 through the fish whole-genome duplication event, little information is available on its molecular function and physiological role. The present study brings biological data supporting the presence of OC2 in the mineral phase of teleost fish bone and its association with the mineral phase together with OC1. The occurrence of OC2 forms with different levels of phosphorylation or γ-carboxylation, and with amino acid substitutions was observed. Comparative analysis of mature peptide sequences revealed the high conservation existing between OC1 and OC2, in particular within the core γ-carboxyglutamic acid domain, and suggests that both protein forms may have the same function, i.e., binding of calcium ions or hydroxyapatite crystals.

Two-dimensional proteomics as a tool to evaluate nutritional effects in farmed fish

The use of proteomics in fish research is at a relatively early stage compared to terrestrial vertebrates. It has already been applied in the field of fish nutrition, enabling to point out metabolic changes occurring in response to dietary manipulations such as a variation in energy content, dietary nitrogen composition, lipid composition or the incorporation of plant protein sources in aquafeeds (Gomez-Requeni et al., 2011; Hamza et al., 2010; Kolditz et al., 2008; Martin et al., 2003; Sveinsdottir and Gudmundsdottir 2010). Of particular interest in the developing finfish aquaculture industry is to understand the nutritional requirements of the faster growing and more fragile larval and juvenile stages. However, the application of the proteomic approach is more challenging during the larval stage, due to the small size of the individuals and thereby the considerable amount of material needed for such an analysis, especially when the focus is a specific tissue.

Assessing fish quality in aquaculture: a proteomics approach

Aquaculture has shown an amazing growth rate in fish production over the last decade, though nowadays it is a very competitive market in the food industry. Fish and shellfish demand will continue to grow, in part as a response to population growth. Provision of seafood from capture fish is declining and is partly not sustainable. Seafood from aquaculture will potentially overcome this supply issue. It can deliver a product of defined quality, composition and safety to the market in all seasons of the year enabling a greater penetration of fish products in consumer’s diet.

Proteomics as a tool to understand fish stress in aquaculture

Physiological and psychological stress are important concerns in economic sectors that rely on animal husbandry, particularly in finfish aquaculture, as impaired fish welfare often implies worse fish health, productivity and final product quality traits. Moreover, this also brings obvious ethical implications.