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[Proximal analysis, fatty acids profile, essential amino acids and mineral content in 12 species of fishes of commercial importance in Venezuela].

Proximate composition, fatty acid profile, essential aminoacid and minerals were determined in twelve fish species (armadillo, bocachico, cachama, carpeta, corvina, lisa, mero, merluza, pargo, robalo, tilapia and trucha). Proximate analysis: moisture, protein and ash, were performed using AOAC methodology, fat by Bligh and Dyer method, fatty acids by Gas Chromatography, aminoacid using High Performance Liquid Chromatography and minerals by spectrophotometric method. Results showed that moisture varies between 70.49% for Armadillo and 78.64% for Mero, protein between 18.70% for Merluza and 25.53 for Armadillo, ash between 0.94% for Mero and 2.13% for Carpeta and fat between 1.12% for Pargo and 6.15% for Cachama. Unsaturated fatty acids (omega 3) were the most common found for all the spices. Essential amino acids studied were present in all the spices. Tilapia (10.938 g/100 g of fish), Bocachico (9.231 g/100 g of fish) and Mero (8.738 g/100 g of fish) shown greater content of essential amino acids. Phosphorous was the most concentrated mineral with a mean value of 238.13 mg/100 g of fish followed by calcium with 42.11 mg/100 g of fish. It was concluded that all studied species are an excellent source of protein, omega 3 fatty acids and minerals.

Amino Acids, Essential↗

Biochemical selection systems for mammalian cells: the essential amino acids.

The essential amino acid requirement of cultured mammalian cells can be satisfied by 19 amino acid derivatives. This finding (a) confirms the results of animal nutritional studies and (b) identifies 19 essential amino acid derivatives and should permit the isolation of a new class of auxotrophic mutants. Five naturally occurring auxotrophic markers have been detected in this survey; namely, inability to utilize cystathionine and citrulline in Chinese hamster ovary (CHO) cells, inability to metabolize citrulline by HTC+hepatoma cells, and confirmation of Eagle's observation that KB cells can utilize homocystine in place of methionine or cystine and D-cystine in place of L-cystine.

Amino Acids↗

Response to lactating dairy cows to abomasal infusion of amino acids.

Essential amino acids most limiting for milk production and/or secretion of milk protein were determined in five trials involving infusion of amino acids into the abomasum of lactating Holstein cows. Cows were fed corn-based rations containing 10.7 to 11.5% crude protein (dry matter basis) which exceeded standard allowances for energy. All trials were Latin-square designs with 9-day periods. The abomasal infusion of methionine had no effect on secretion of milk, milk protein, or milk fat. Lysine infusion resulted in 16% of the total response in yield of milk protein that was obtained with either the 10 essential amino acids or sodium caseinate while infusion of lysine and methionine together accounted for 43% of the total response. This suggested that lysine and methionine were first and second limiting, or co-limiting, for secretion of milk protein when rations consisting primarily of corn, corn silage, and alfalfa-grass hay were fed. The primary effect was on content of milk protein rather than milk yield. In general, amino acid infusions had no effect on feed intake, milk fat, and nonprotein nitrogen content of milk. Little change occurred in concentrations in plasma of other amino acids when lysine and methionine were infused together. When concentrations were lowered, indicating increased protein synthesis, changes were too small to be statistically significant.

Abomasum↗

Comparison of the effects of keto acid analogues and essential amino acids on nitrogen homeostasis in uremic patients on moderately protein-restricted diets.

Comparisons of isonitrogenous supplements (1.2 g N) of essential amino acids and five keto acid analogues with four essential amino acids were made in seven patients with stable chronic renal failure (creatinine clearance, 4.6 to 16 ml/min) on moderately protein-restricted diets (4.60 to 7.8 g N per day). Full nitrogen balance data on the four patients who have already completed studies lasting 24 weeks are presented. No benefits of keto acid over amino acid supplements were observed. Two transient episodes of hypercalcemia occurred during keto acid treatment. There was no improvement of renal function with keto acids. Also, no carry-over effects were seen after keto acid treatment. It is concluded that any beneficial effects of keto acids in patients with chronic renal failure are only likely to occur in those taking a diet of less than 30 g protein daily.

Adult↗

Pigs' gastrointestinal microflora provide them with essential amino acids.

The synthesis of essential amino acids by the gut microflora of pigs, and their absorption, were assessed from the incorporation of (15)N from dietary (15)NH(4)Cl and of (14)C from dietary (14)C-polyglucose into amino acids in the body tissues of four pigs. Both (15)N and (14)C were incorporated into essential amino acids in body protein. Because pig tissues cannot incorporate (15)N into lysine or (14)C into essential amino acids, the labeling of these amino acids in body protein indicated their microbial origin. The absorption of microbial amino acids was estimated by multiplying the total content of each amino acid in the body by the ratio of the isotopic enrichment of the amino acid in the body to that in microbial protein. Because the ratio of (14)C:(15)N in body lysine was closer to that in the microflora of the ileum than to that of the cecum, absorption was assumed to take place exclusively in the ileum. The estimates of microbial amino acid absorption from (14)C-labeling were as follows (g/d): valine 1.8, isoleucine 0.8, leucine 2.0, phenylalanine 0.3 and lysine 0.9, whereas for lysine, the estimate from (15)N-labeling was 1.3 g/d. We conclude that the gastrointestinal microflora contribute significantly to the amino acid requirements of pigs.

Amino Acids, Essential↗

Albumin synthesis in cultured hempatoma cells. Regulation by essential amino acids.

The effects of essential amino acids on albumin synthesis by a mouse hepatoma cell line have been investigated. The amino acids tested were tryptophan, phenylalanine, histidine, isoleucine and leucine. Cellular rates of synthesis (molecules albumin/cell per min) were determined from rates of [3H]leucine incorporation into immunoprecipitable albumin in the culture medium. The effects of amino acids on albumin synthesis fall into three distinct groups. The concentration of tryptophan producing half-maximal synthesis is 4 micronM. The corresponding concentration for leucine is 100 micronM. Histidine, phenylalanine and isoleucine were very similar, the half-maximal concentrations being approximately 15 micronM. The concentrations of amino acids producing half-maximal synthesis correlate directly with the amino acid composition of albumin. The levels of these essential amino acids necessary to saturate albumin synthesis have been compared with amino acid levels in normal plasma.

Albumins↗

Response of rainbow trout (Oncorhynchus mykiss) to supplements of individual essential amino acids in a semipurified diet, including an estimate of the maintenance requirement for essential amino acids.

We studied the effects of increasing dietary concentrations of each of the following amino acids on growth, feed intake, feed conversion ratio and composition of gain in rainbow trout in six dose-response experiments: L-lysine, L-tryptophan, L-histidine, L-valine, L-leucine and L-isoleucine. Semipurified diets containing 20.1 MJ digestible energy/kg dry matter, with wheat gluten and crystalline amino acids as sole sources of amino acids, were fed to rainbow trout [initial mean body weight (BW) 40-51 g, depending on the amino acid studied]. In one series of 24 diets, lysine concentration ranged from 4.5 to 58.0 g/kg dry matter; in five further series of 12 diets each, concentrations ranged from (in g/kg dry matter): tryptophan, 1.3 to 5.6; histidine, 2.6 to 13.5; valine, 6.2 to 34.2; leucine, 10.0 to 42.0 and isoleucine, 5.0 to 15.3. Each diet was fed to a group of 20 fish for 53-64 d, depending on the amino acid studied. Dry matter intake, weight gain, feed conversion ratio, protein concentration of gain and total protein deposition followed exponential response functions. To achieve 95% of the maximum protein deposition, dietary concentrations of 27.7 g lysine, 2.0 g tryptophan, 5.8 g histidine, 15.7 g valine, 13.6 g leucine and 13.7 g isoleucine/kg dry matter were required. Maintenance requirements, estimated from exponential functions for protein deposition, were [in mg/(100 g BW.d)]: lysine, 1.93; tryptophan, 1.05; histidine, 1.07; valine, 2.92; leucine, 8.26 and isoleucine, 0.91. This corresponds to 4% of the requirement for protein deposition for lysine and isoleucine but 32% for leucine, with the other amino acids being intermediate. Therefore, different dietary amino acid requirement patterns were derived from protein deposition data depending on the chosen level of performance.

Amino Acids, Essential↗

Effect of L-malic and citric acids metabolism on the essential amino acid requirements for Oenococcus oeni growth.

AIMS: The purpose of this work was to study the effect of L-malic and/or citric acids on Oenococcus oeni m growth in deficient nutritional conditions, and their roles as possible biosynthetic precursors of the essential amino acids. METHODS AND RESULTS: Bacterial cultures were performed in synthetic media. Bacterial growth rate was reduced or annulled when one amino acid was omitted from basal medium, especially for members of aspartate family, except lysine. The organic acids increased or restored the growth rates to the respective reference values. In each medium deficient in one essential amino acid, the L-malic acid utilization was accompanied by an increase of L-lactic acid concentration and accounted for approximately 100%l-malic acid consumed. D-lactic acid formation from glucose decreased in the medium without cysteine. Except for tyrosine, the recovery of glucose-citrate as D-lactic acid was lower than in the complete medium when asparagine, isoleucine or cysteine were excluded. The ethanol and acetate production was not modified. CONCLUSIONS: L-malic and citric acids favoured Oenococcus oeni m growth in nutritional stress conditions. Specifically citric acid was involved in the biosynthesis of the aspartate-derived essential amino acids and glucose in the cysteine biosynthesis. SIGNIFICANCE AND IMPACT OF THE STUDY: Such beneficial effect of l-malic and citric acids on amino acids requirements of Oenococcus oeni m have great significance considering the low amino acids concentration in wine.

Amino Acids↗

Practical prospects for the therapeutic use of essential amino acid analogues.

Interest in essential amino acid analogues developed as a means of diverting ammonia nitrogen into protein synthesis in patients with chronic renal failure, urea cycle enzyme defects and hepatic failure. Long-term practical therapeutic value has so far only been proved in children with urea cycle defects. Recent work confirms that the alpha-keto acid of leucine in particular alters protein turnover and may prove of wide practical application to improve nitrogen balance in post-operative patients and others with severe illness.

Amino Acids, Essential↗