Growth, nutrient utilization and parameters of mineral metabolism in Nile tilapia Oreochromis niloticus (Linnaeus, 1758) fed plant-based diets with graded levels of microbial phytase.

Diets with graded levels of the experimental microbial phytase SP1002 (0, 500, 1000, 2000 and 4000 FTU/kg) were fed to juvenile Nile tilapia (average BW = 68.8 g) for 60 days (n = 4). A digestibility trial ran parallel to the growth trial using 0.3 g TiO2/100 g as an indigestible marker. The efficiency of phytase supplementation was evaluated by parameters of growth response, crude protein and mineral utilization (using body composition data), apparent nutrient digestibility, mineral content in scale and vertebra and inorganic phosphorus in blood plasma. Data were submitted to ANOVA and Tukey-test using SAS-program. Significant improvements (p < 0.01) were found for growth, FCR and SGR, mainly for diets with 1000 and 2000 FTU/kg phytase supplementation. Protein utilization was significantly increased and maximized between 1000 and 2000 FTU/kg. Phosphorus utilization increased significantly up to 4000 FTU/kg. Digestibility of protein and phosphorus was also significantly improved. Phosphorus concentration in the blood, vertebra and scale increased significantly after phytase addition. Similarly, calcium and magnesium concentration in vertebra and scale were increased. Generally, phytase supplementation between 1000 and 2000 FTU/kg resulted in growth rates and mineralization parameters similar to a control diet with inorganic phosphorus.

Co-assembly of plasma and cellular fibronectins into fibrils in human fibroblast cultures.

Exogenous plasma and endogenous cellular fibronectins on the surface of cultured fibroblasts and in extracellular matrix fibrils were colocalized by fluorescent and high voltage immunoelectron microscopy. Fibroblast cultures grown in the presence or absence of cycloheximide were incubated with exogenous plasma fibronectin labeled with fluorescein isothiocyanate. A monoclonal antibody specific for the EIIIA sequence of cellular fibronectin was used to detect cellular fibronectin. A rabbit antifluorescein antibody identified fluoresceinated plasma fibronectin. In cultures incubated in the presence of cycloheximide, plasma fibronectin was bound to the cell surface and was assembled into extracellular fibrils. In cultures grown in the absence of cycloheximide, plasma and cellular fibronectins were observed in the same matrix fibrils and in the same locations on the cell surface. There was not, however, random admixture of the two proteins.