The eect of dietary protein and energy content on the activity of digestive enzymes (total proteinases, trypsin, chymotrypsin a-amylase and lipase), and growth and survival of Litopenaeus setiferus postlarvae was investigated under controlled conditions. There was a clear relationship between the diet fed to the postlarvae, growth and survival. Highest weight gain (2110 96.7%) was obtained with a 400 g kg )1 protein and low energy diet (13.9 kJ g )1 ) (P < 0.05). The optimal protein to energy ratio (P/E) estimated was 28.8 mg of protein kJ )1 . Good survival was obtained with low energy diets containing between 200 and 400 g kg )1 protein and with high energy diets containing 300±500 g kg )1 protein.Higher values for total proteinases, trypsin and a-amylase were obtained with the low energy, 400 g kg )1 protein diet. Chymotryptic activity was considerably lower than that of other proteinases and lipase activity was too low to be reliably measured with the turbidimetric method employed. Total proteinase activity was signi®cantly lower than in experimentally grown postlarvae. The a-amylase activity was at least two orders of magnitude higher in wild postlarvae than in animals fed with the best experimental diet. Protein requirement was related to total energy content of the diet: best growth and digestive enzyme activity coincide with the low energy, 400 g kg )1 protein diet. These results suggest that dietary carbohydrates cannot spare protein because growth rates obtained with diets containing 200±300 g kg )1 protein (337 and 226 g kg )1 dextrin content, respectively) were signi®cantly lowered.
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Type I procollagen was purified from cultured fibroblasts of a proband with a lethal variant of osteogenesis imperfecta. The protein was a mixture of normal procollagen and mutated procollagens containing a substitution of cysteine for glycine in either one pro alpha 1(I) chain or both pro alpha 1(I) chains, some or all of which were disulfide-linked through the cysteine at position alpha 1-748. The procollagen was then examined in a system for generating collagen fibrils de novo by cleavage of the pCcollagen to collagen with procollagen C-proteinase [Kadler et al. (1987) J. Biol. Chem. 262, 15696-15701]. The mutated collagens and normal collagens were found to form copolymers under a variety of experimental conditions. With two preparations of the protein that had a high content of alpha 1(I) chains disulfide-linked through the cysteine alpha 1-748, all the large structures formed had a distinctive, highly branched morphology that met one of the formal criteria for a fractal. Preparations with a lower content of disulfide-linked alpha 1(I) chains formed fibrils that were 4 times the diameter of control fibrils. The formation of copolymers was also demonstrated by the observation that the presence of mutated collagens decreased the rate of incorporation of normal collagen into fibrils. In addition, the solution-phase concentration at equilibrium of mixtures of mutated and normal collagens was 5-10-fold greater than that of normal collagen.(ABSTRACT TRUNCATED AT 250 WORDS)
A 1-step procedure for the easy and rapid purification of milligram amounts of antigen B from a crude extract of Taenia solium cysticerci is described here. This procedure takes advantage of the property of the antigen B to bind to collagen and is based on antigen adsorption to polymeric collagen.
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