Growth of soybean plants cultivated in soil and fertilized with silicon.

Although silicon is not considered an essential element, in some crops such as soybeans, its supply can stimulate plant development and plant production. The growth of soybean cultivars in Cerrado soil subjected to the application of silicon doses was studied. The experiment was conducted in a greenhouse at the Instituto Federal do Amapá - IFAP/Campus Agrícola Porto Grande. The experimental design was completely randomized, arranged in a 5x2 factorial scheme, with four replications. The factors consisted of the control treatment (without Si) and four doses of Si (250, 500, 750 and 1000 mg pot-1 of SiO2), and two soybean cultivars (BRS Tracajá and FTS Paragominas). Growth variables were analyzed, such as: plant height, stem diameter; and dry matter of shoots and roots. Silicon influenced the increase in height when evaluating the cultivars and isolated doses, the same behavior was observed in the dry matter production of the aerial part and total. The element silicon helps in the improvement and gain in height and other evaluated agronomic characteristics, but studies with this element must be more applied, to obtain the answer for other variables and study conditions.

Growth and production of cowpea beans under potassium doses in soil of cerrado in Amapá, Brazil.

The cowpea bean [Vigna unguiculata (L.) Walp.], a legume of great socioeconomic importance, it was previously cultivated exclusively for subsistence and commercial purposes, especially in the North and Northeast regions. This crop has a low production cost and high nutritional value, in addition to a high potential for productivity growth and expansion to other regions. The objective of this work was to evaluate parameters of growth and production in cowpea culture, as a function of potassium fertilization in soil of the cerrado of Amapá. The parameters of growth and production of the cowpea culture were evaluated, as a function of potassium fertilization in the soil of the cerrado of Amapá. The experiment was conducted in a greenhouse, using a completely randomized experimental design, with four replications, in a 5x2 factorial scheme, totaling 40 experimental units, which were composed of plastic pots containing 7 dm3 of soil collected from the arable layer (0-20 cm ) of a typical Hyperdystrophic Yellow Argisol, with a sandy clay loam texture, in a cerrado area in the municipality of Porto Grande-AP. The factors consisted of the control treatment (without K), four doses of K (45, 90, 135 and 180 kg ha-1) in the form of potassium chloride, and two cowpea cultivars (Pretinho and BRS Tumucumaque). The cultivar BRS Tumucumaque shows better growth and production of cowpea plants. Doses of 90 kg ha-1 provided greater height (98.75 cm) and stem diameter (10.0 mm). As for production, the dose of 135 kg ha-1 caused greater grain weight gain (5.25 g) and dry mass of pods (13.92 g), and the doses of 90 and 180 kg ha-1 induced greater number and length of pods (3.16 pods) respectively. These results show better responsiveness of the BRS Tumucumaque cultivar at doses of 90, 135 and 180 kg ha-1 in the type of soil where the study was conducted.

Chickens (Gallus domesticus) are natural intermediate hosts of Neospora caninum.

Neospora caninum naturally infects many mammal species, but has not previously been demonstrated in birds. We examined sera for N. caninum antibodies from 200 outdoor chickens and from 200 chickens confined indoors in the state of Bahia, Brazil. Seroprevalence was greater in outdoor chickens (23.5% versus 1.5%, P<0.001). PCR testing for N. caninum was positive in six of 10 seropositive chickens. Amplicons from two of these were sequenced and had 97-98% nucleotide identity with N. caninum. This finding extends the list of intermediate hosts of N. caninum to include birds and may have important epidemiological consequences.

Metabolism and disposition of alpha-methylstyrene in rats.

alpha-Methylstyrene (AMS) is a volatile hydrocarbon used primarily in the production of specialty polymers and resins. In the present study, the tissue distribution, metabolism, and excretion of [(14)C]AMS was investigated in male rats after i.v. administration (11 mg/kg). Over 90% of AMS administered intravenously to rats was excreted in 72 h. Urinary excretion accounted for 86% of the administered dose, volatile breath and feces accounted for 2.2 and 1.9%, respectively, and elimination as carbon dioxide was negligible. Metabolites were isolated from rat urine following a high oral dose of AMS (1000 mg/kg) and characterized using gas chromatography/mass spectrometry and NMR spectrometry. The metabolites were 2-phenyl-1,2-propanediol (3% of urinary radioactivity) and its glucuronide (50%), atrolactic acid (27%), S-(2-hydroxy-2-phenylpropyl)-N-acetylcysteine (13%), and 2-phenylpropionic acid (1%); the glucuronides and mercapturates were each conjugated on the methylene carbon beta to the ring. The presence of both of the diastereomeric isomers of the mercapturates and of the glucuronides suggested that the initial epoxidation of AMS was not stereoselective and proceeded with addition of active oxygen to yield enantiomeric epoxides. Incubation of AMS with human liver slices produced the same metabolites as those excreted in rat urine, with 2-phenyl-1,2-propanediol present as the predominant metabolite after 5 h of incubation.

Reduction of 1,3-diphenyl-1-triazene by rat hepatic microsomes, by cecal microflora, and in rats generates the phenyl radical metabolite: nn ESR spin-trapping investigation.

An ESR spin-trapping technique was used to determine whether free radical metabolites are formed as a result of the reduction of 1, 3-diphenyl-1-triazene (DPT) in vivo and in vitro by components of the cytochrome P450 (P450) mixed-function oxidase system in microsomes or by gut microflora in anaerobic cecal incubations. The ESR spectrum of the DMPO-phenyl radical adduct was detected in a microsomal incubation containing DPT, DMPO, and NADPH with the following hyperfine coupling constants: a(N) = 15.95 G and = 24.37 G. The amplitude of the spectrum from the phenyl radical adduct generated in microsomal incubations of DPT with DMPO and NADPH was not attenuated by the P450 inhibitor 1-aminobenzotriazole (ABT) or by carbon monoxide, indicating that P450 is not significantly involved in phenyl radical formation. The formation of a DMPO-phenyl radical adduct was also catalyzed by recombinant human cytochrome P450 reductase. Addition of anti-rat P450 reductase antibody led to an attenuation of the signal in incubations containing either microsomes or reductase. Low concentrations of DMPO-phenyl radical adducts were detected by ESR in the toluene extract of cecal contents containing DPT and the spin trap. In the in vivo experiments with rats treated with DPT and the spin trap DMPO, the six-line ESR signal of the DMPO-phenyl radical adduct was readily detected in bile 40-60 min after rats were treated with DPT and DMPO. The results show for the first time that the phenyl radical is formed by the reduction of DPT and may indicate a toxic potential for this chemical.

Absorption, metabolism, and disposition of 1,3-diphenyl-1-triazene in rats and mice after oral, i.v., and dermal administration.

1,3-Diphenyl-1-triazene (DPT) is used in the synthesis of polymers and dyes, and has been found as an impurity in the color additives D&C Red 33 and FD&C Yellow 5. [(14)C]DPT, randomly labeled in the phenyl rings, was used to investigate its disposition in rodents. Dermal doses to rats and mice (2 and 20 mg/cm(2)) were poorly absorbed (