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Cupriavidus necator JMP134 utilizes meta-nitrophenol (MNP) as a sole source of carbon, nitrogen, and energy. The metabolic reconstruction of MNP degradation performed in silico suggested that the mnp cluster might have played important roles in MNP degradation. In order to experimentally confirm the prediction, we have now characterized mnpA-encoded meta-nitrophenol nitroreductase involved in the initial reaction of MNP degradation. Real-time PCR analysis indicated that mnpA played an essential role in MNP degradation. MnpA was purified to homogeneity as His-tagged proteins and was considered to be a dimer as determined by gel filtration. MnpA was an MNP nitroreductase with a tightly bound flavin mononucleotide (FMN), catalyzing the partial reduction of MNP to meta-hydroxylaminophenol via meta-nitrosophenol in the presence of NADPH and oxygen. The accumulation of meta-nitrosophenol was confirmed with the results of liquid chromatography–diode array detection and time-of-flight mass spectrometry for the first time. The low Km and high kcat of MnpA as well as MNP-inducible transcription of mnpA suggested that MNP was the physiological substrate for this nitroreductase. In addition, the phylogenetic analysis revealed that nitroreductases of known physiological function including MnpA constituted a new clade in the nitro-FMN-reductase superfamily. [ABSTRACT FROM AUTHOR]

Some key aspects of the reproductive strategy of the brown trout ( Salmo trutta fario L.) in the Yadong River, Tibet, including spawning season, age at sexual maturity, fecundity and egg size, have been studied. The majority of the samples were less than 215 mm and age ranged from 1 to 4 in both sexes, indicating that the majority of the fish were younger and the pressure by overfishing was high. The spawning periodicity was determined to be between the end of October and January, mainly in November and December. The ratio of male to female brown trout population (1.29:1 with P > 0.05) suggested no sex significant differences, although males were significantly more abundant than females in October ( P < 0.0001) on monthly basis. Age and size of males and females at maturity was different and males matured earlier than females. Fecundity was markedly correlated with their body weight ( P < 0.001, r = 0.9255), standard length ( P < 0.01, r = 0.8879), and gonad weight ( P < 0.001, r = 0.9366). The mean size of mature eggs in the spawning season was: 4.0 ± 0.45 mm and tended to increase along with the female spawners size ( P < 0.001, r = 0.9641). Further researches about the brown trout population in the Yadong River should be conducted on issues such as artificial reproduction, culture, conservation, management, and restocking. [ABSTRACT FROM AUTHOR]

Abstract  Arginine plays an important role regulating nutrient metabolism, but the underlying mechanisms are largely unknown. This study was conducted to determine the effect of dietary arginine supplementation on the metabolome in serum of growing pigs using 1H nuclear magnetic resonance spectroscopy. Sixteen 120-day-old pigs (48 ± 1 kg) were randomly assigned to one of two groups, representing supplementation with 0 or 1.0% l-arginine to corn- and soybean meal-based diets. Serum was collected after a 46-day period of treatment. Dietary arginine supplementation decreased fat deposition and increased protein accretion in the body. Principal component analysis showed that serum concentrations of low density lipoprotein, very low density lipoprotein, and urea were lower, but concentrations of creatinine, tricarboxylic acid cycle metabolites, ornithine, lysine and tyrosine were greater in arginine-supplemented than in control pigs. Additionally, the arginine treatment affected serum concentrations of nitrogenous and lipid signaling molecules (glycerophosphorylcholine and myo-inositol) and intestinal bacterial metabolites (formate, ethanol, methylamine, dimethylamine, acetate, and propionate). These novel findings suggest that dietary arginine supplementation alters the catabolism of fat and amino acids in the whole body, enhances protein synthesis in skeletal muscle, and modulates intestinal microbial metabolism in growing pigs. [ABSTRACT FROM AUTHOR]