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Chemical composition and ruminal degradation kinetics of crude protein and amino acids, and intestinal digestibility of amino acids from tropical forages

Miranda,Lidia Ferreira; Rodriguez,Norberto Mario; Pereira,Elzânia Sales; Queiroz,Augusto César de; Sainz,Roberto Daniel; Pimentel,Patrícia Guimarães; Gontijo Neto,Miguel Marques
Fonte: Sociedade Brasileira de Zootecnia Publicador: Sociedade Brasileira de Zootecnia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2012 Português
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The objective of this research was to determine the chemical composition and ruminal degradation of the crude protein (CP), total and individual amino acids of leaves from tropical forages: perennial soybean (Neonotonia wightii), cassava (Manihot esculenta), leucaena (Leucaena leucocephala) and ramie (Boehmeria nivea), and to estimate the intestinal digestibility of the rumen undegradable protein (RUDP) and individual amino acids of leaves from the tropical forages above cited, but including pigeon pea (Cajanus cajan). Three nonlactating Holstein cows were used to determine the in situ ruminal degradability of protein and amino acids from leaves (6, 18 and 48 hours of ruminal incubation). For determination of the intestinal digestibility of RUDP, the residue from ruminal incubation of the materials was used for 18 hours. A larger concentration of total amino acids for ramie and smaller for perennial soybean were observed; however, they were very similar in leucaena and cassava. Leucine was the essential amino acid of greater concentration, with the exception of cassava, which exhibited a leucine concentration 40.45% smaller. Ramie showed 14.35 and 22.31% more lysine and methionine, respectively. The intestinal digestibility of RUDP varied from 23.56; 47.87; 23.48; 25.69 and 10.86% for leucaena...

Utilization of Glucose and the Effect of Organic Compounds on the Chemolithotroph Thiobacillus ferrooxidans

Tabita, Robert; Lundgren, D. G.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/1971 Português
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The utilization of glucose by the chemolithotroph Thiobacillus ferrooxidans results in a repression of the ability to oxidize iron, the substrate for autotrophic growth. An assay with resting cells was used to measure iron oxidation rates. Concomitant with the decreased iron oxidation rates, the enzyme responsible for carbon dioxide fixation, ribulose diphosphate (RuDP) carboxylase, was also repressed. Maximum iron oxidation rates precede peak RuDP carboxylase levels, consistent with the role of these processes in autotrophic metabolism in nonrepressed cells. The degree of iron oxidation repression depends on the organic substrate supplied, as does the level of RuDP carboxylase. The uptake of glucose parallels an increase in synthesis of glucose-6-phosphate dehydrogenase and the accumulation in cells of poly-β-hydroxybutyrate. The organism is also capable of growing on glucose and other organic supplements in the absence of its inorganic energy source; growth rates depend on the organic substrate supplied.

Regulation of Autotrophic and Heterotrophic Carbon Dioxide Fixation in Hydrogenomonas facilis1

McFadden, Bruce A.; Tu, Chang-Chu L.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /03/1967 Português
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After growth on various carbon sources, sonic extracts of Hydrogenomonas facilis contained ribulosediphosphate (RuDP) carboxylase and phosphoribulokinase (Ru5-P kinase). After very short sonic treatment, a reductive adenosine triphosphate (ATP)-dependent incorporation of 14CO2 was also detectable. Reduced nicotinamide adenine dinucleotide (NADH2) served as reductant 30-fold more effectively than reduced nicotinamide adenine dinucleotide phosphate (NADPH2). Adenosine 5′-phosphate (AMP) and adenosine 5′-pyrophosphate (ADP) inhibited Ru5-P kinase and NADH2-, ATP-dependent CO2 fixation. The levels and duration of CO2 fixation suggested that it is a cyclic process. The requirement of reduced pyridine nucleotide and ATP and the sensitivity of fixation to AMP and ADP support the conjecture that it occurs via the Calvin cycle. After thorough study of variables affecting catalysis, specific activities (millimicromoles of substrate disappearing per milligram of protein) at 30 C were determined for RuDP carboxylase (C), Ru5-P kinase (K) and ATP-, NADH2- dependent CO2 fixation (CO2 F) after growth autotrophically on fructose, glucose, ribose, glutamate, lactate, succinate, and acetate. Values for these growth modes were, respectively—for C: 67.3...

Regulation of Ribulose 1,5-Diphosphate Carboxylase by Substrates and Other Metabolites: Further Evidence for Several Types of Binding Sites 1

Chu, Douglas K.; Bassham, James A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1975 Português
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Ribulose 1,5-diphosphate carboxylase (RuDPCase, EC 4.1.1.39) isolated from spinach leaves is metabolically regulated at 10 mm Mg2+ and low CO2 concentrations by its substrates (RuDP and CO2) and by effectors which include 6-phosphogluconate (6-PGluA), NADPH, and fructose 1,6-diphosphate (FDP), but not fructose 6-phosphate. Physiological concentrations of RuDP severely inhibit the enzyme activity when the enzyme has not been preincubated with HCO3− and Mg2−, and this inactivity persists for 20 minutes or longer after 1 mm HCO3− and 10 mm Mg2+ are added. Maximum activity requires that the preincubation mixture also include either 0.01 mm 6-PGluA or 0.5 mm NADPH.

Development of Ribulose 1,5-Diphosphate Carboxylase in Nonphotosynthetic Endosperms of Germinating Castor Beans 1

Gillen, Lee Ann Fry; Wong, Joshua H. H.; Benedict, C. Roy
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1976 Português
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Ribulose 1,5-diphosphate (RuDP) carboxylase has been partially purified from dark-grown nonphotosynthetic endosperms of germinating castor beans (Ricinus communis var. Hale). The Km values for RuDP, HCO3−, and Mg2+ are 0.51, 33, and 1.78 mm, respectively. The pH optimum for the carboxylation reaction is pH 7.5. Germination is required for the development of the carboxylase in the endosperms. The enzyme reaches a maximal activity in 4- to 5-day-old dark-grown seedlings (which have an endosperm weight of approximately 0.75 g fresh weight/bean) and then declines. Total endosperm carboxylase activity is 1230 nmoles/min·g fresh weight which is 25 and 50% of the total activity developed in soybean and maize leaves, respectively. Specific activity of the carboxylase in crude soluble endosperm preparations (which contain enzymic and storage protein) is 0.05 μmole/min·mg protein. This is 5 times greater than the specific activity of RuDP carboxylase in soluble preparations from etiolated leaves. During germination the Vmax of the endosperm carboxylase for RuDP increases 10-fold. Development of the enzyme is inhibited 90% by the exposure of the endosperm to 2 μg/ml cycloheximide or 50 μg/ml chloramphenicol. Light (or phytochrome Pfr) is not required for the synthesis of the enzyme. Electron photomicrographs of dark-grown endosperm cells (with peak RuDP carboxylase activity) show proplastids with several invaginations of the inner membrane but no prolamellar-like structures.

pH Dependence of Photosynthesis and Photorespiration in Soybean Leaf Cells

Servaites, Jerome C.; Ogren, William L.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /11/1977 Português
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The effect of pH on the kinetics of photosynthesis, O2 inhibition of photosynthesis, and photorespiration was examined with mesophyll cells isolated from soybean (Glycine max [L.] Merr.) leaves. At constant, subsaturating bicarbonate concentration (0.5 mm), O2 inhibition of photosynthesis increased with increasing pH because high pH shifts the CO2-bicarbonate equilibrium toward bicarbonate, thereby reducing the CO2 concentration. At constant, substrating CO2 concentrations, cell photorespiration decreased with increasing pH. This was indicated by decreases in the CO2 compensation concentration, O2 inhibition of photosynthesis, and glycine synthesis. Km(CO2) values for isolated cell photosynthesis and in vitro ribulose-1, 5-diphosphate carboxylase activity decreased with increasing pH, while the Ki(O2) for both systems was similar at all pH values. The responses to pH of the corresponding kinetic constants of cell photosynthesis and in vitro RuDP carboxylase with respect to CO2 and O2 were identical. This provides additional evidence that the relative rates of photosynthesis and photorespiration in C3 plants are determined by the kinetic properties of RuDP carboxylase.

BIOGENESIS OF CHLOROPLAST MEMBRANES : II. Plastid Differentiation during Greening of a Dark-Grown Algal Mutant (Chlamydomonas reinhardi)

Ohad, I.; Siekevitz, P.; Palade, G. E.
Fonte: The Rockefeller University Press Publicador: The Rockefeller University Press
Tipo: Artigo de Revista Científica
Publicado em 01/12/1967 Português
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Dark-grown cells of the y-1 mutant of Chlamydomonas reinhardi contain a partially differentiated plastid lacking the photosynthetic lamellar system. When exposed to the light, a rapid synthesis of photosynthetic membranes occurs accompanied by synthesis of chlorophyll, lipids, and protein and extensive degradation of the starch reserve. The process is continuously dependent on illumination and is completed within 6–8 hr in the absence of cell division. Photosynthetic activity (O2 evolution, Hill reaction, NADP photo-reduction, and cytochrome f photooxidation) parallels the synthesis of pigment and membrane formation. During the greening process, only slight changes occur in the levels of soluble enzymes associated with the photosynthetic process (RuDP-carboxylase, NADP-linked G-3-P dehydrogenase, alkaline FDPase (pH 8)) as compared with the dark control. Also cytochrome f concentration remains almost constant during the greening process. The kinetics of the synthesis of chlorophyll, formation of photosynthetic membranes, and the restoration of photosynthetic activity suggest that the membranes are assembled from their constituents in a single-step process.

BIOGENESIS OF CHLOROPLAST MEMBRANES : I. Plastid Dedifferentiation in a Dark-Grown Algal Mutant (Chlamydomonas reinhardi)

Ohad, I.; Siekevitz, P.; Palade, G. E.
Fonte: The Rockefeller University Press Publicador: The Rockefeller University Press
Tipo: Artigo de Revista Científica
Publicado em 01/12/1967 Português
Relevância na Pesquisa
16.943906%
This paper describes the morphology and photosynthetic activity of a mutant of Chlamydomonas reinhardi (y-1) which is unable to synthesize chlorophyll in the dark. When grown heterotrophically in the light, the mutant is indistinguishable from the wild type Chlamydomonas. When grown in the dark, chlorophyll is diluted through cell division and the photosynthetic activity (oxygen evolution, Hill reaction, and photoreduction of NADP) decays at a rate equal to or faster than that of chlorophyll dilution. However, soluble enzymes associated with the photosynthetic process (alkaline FDPase, NADP-linked G-3-P dehydrogenase, RuDP carboxylase), as well as cytochrome f and ferredoxin, continue to be present in relatively high concentrations. The enzymes involved in the synthesis of the characteristic lipids of the chloroplast (including mono- and digalactoside glycerides, phosphatidyl glycerol, and sulfolipid) are still detectable in dark-grown cells. Such cells accumulate large amounts of starch granules in their plastids. On onset of illumination, dark-grown cells synthesize chlorophyll rapidly, utilizing their starch reserve in the process. At the morphological level, it was observed that during growth in the dark the chloroplast lamellar system is gradually disorganized and drastically decreased in extent...

Chemical composition and ruminal degradation kinetics of crude protein and amino acids, and intestinal digestibility of amino acids from tropical forages.

MIRANDA, L. F.; RODRIGUEZ, N. M.; PEREIRA, E. S.; QUEIROZ, A. C. de; SAINZ, R. D.; PIMENTEL, P. G.; GONTIJO NETO, M. M.
Fonte: Revista Brasileira de Zootecnia, Viçosa, MG, v. 41, n. 3, p. 717-725, 2012. Publicador: Revista Brasileira de Zootecnia, Viçosa, MG, v. 41, n. 3, p. 717-725, 2012.
Tipo: Artigo em periódico indexado (ALICE)
Português
Relevância na Pesquisa
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The objective of this research was to determine the chemical composition and ruminal degradation of the crude protein (CP), total and individual amino acids of leaves from tropical forages: perennial soybean (Neonotonia wightii), cassava (Manihot esculenta), leucaena (Leucaena leucocephala) and ramie (Boehmeria nivea), and to estimate the intestinal digestibility of the rumen undegradable protein (RUDP) and individual amino acids of leaves from the tropical forages above cited, but including pigeon pea (Cajanus cajan). Three nonlactating Holstein cows were used to determine the in situ ruminal degradability of protein and amino acids from leaves (6, 18 and 48 hours of ruminal incubation). For determination of the intestinal digestibility of RUDP, the residue from ruminal incubation of the materials was used for 18 hours. A larger concentration of total amino acids for ramie and smaller for perennial soybean were observed; however, they were very similar in leucaena and cassava. Leucine was the essential amino acid of greater concentration, with the exception of cassava, which exhibited a leucine concentration 40.45% smaller. Ramie showed 14.35 and 22.31% more lysine and methionine, respectively. The intestinal digestibility of RUDP varied from 23.56; 47.87; 23.48; 25.69 and 10.86% for leucaena...

Design and implementation of online game models

Palenzuela Reyes, Marc
Fonte: Universidade Autônoma de Barcelona Publicador: Universidade Autônoma de Barcelona
Tipo: info:eu-repo/semantics/bachelorThesis; Text Formato: application/pdf
Publicado em 11/02/2015 Português
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Make good or even a playable on-line game is not easy. In this paper we explain what are the difficulties of on-line games designing and implementation and propose solutions to those difficulties. We also have made a new transport protocol suitable for those models and three proof of concept games to check the effectiveness of our new taxonomy. After reading this paper you will be able to sort out and design the different on-line models and have a slight idea of a transport protocol design.; Crear un buen juego on-line o incluso jugable no es fácil. En este artículo explicamos cuales son las dificultades a la hora de diseñar e implementar juegos on-line, y proponemos soluciones a esas dificultades. Además hemos creado un nuevo protocolo de transporte adecuado para estos modelos y tres juegos on-line como pruebas de concepto para comprobar la efectividad de nuestra nueva taxonomia. Tras leer este artículo el lector será capaz de clasificar y diseñar los diferentes modelos de juego on-line y tener una leve idea del diseño de un protocolo de transporte.; Crear un bon joc on-line o fins i tot jugable no es fàcil. En aquest article expliquem quines son les dificultats a l'hora de dissenyar i implementar jocs on-line, i proposem solucions a aquestes dificultats. A més a més hem creat un nou protocol de transport adequat per a aquests models i tres jocs on-line com a proves de concepte per a comprovar la efectivitat de la nostra nova taxonomia. Després de llegir aquest article el lector serà capaç de classificar i disenyar els diferents models de joc on-line i tenir una petita idea del disseny de un protocol de transport.