Adaptation and Validation of Colorimetric Methods in Determining Ammonium and Nitrate on Tropical Soils

Inorganic nitrogen (N) determination in soil extracts is a useful tool in studying soil–N interactions. The main method used worldwide is the steam distillation, but colorimetric methodologies show advantages of being quick, simple, sensitive, and higher yield. However, they are subject to disruption when the extract has interfering organic N, limiting its application in tropical soil. The aim of this study is to evaluate colorimetric methods for the determination of NH₄⁺ (through Berthelot reaction) and NO₃^? + NO₂^? (through Griess-Ilosvay reaction) in saline extracts of tropical soils by addition of activated charcoal during the extraction process. It is recommended to use extraction solution of 2 mol L^?1 potassium chloride (KCl) and reaction time of 30 min. Validation parameters confirmed the best performance of the colorimetric methods, revealing results favorable to the addition of the activated charcoal in the extraction process to increase the accuracy and precision of the colorimetric methods.     

Carotenoid Profile of Edible Japanese Seaweeds: An Improved HPLC Method for Separation of Major Carotenoids

An improved multi-step gradient reverse phase high performance liquid chromatography (HPLC) method to simultaneously separate major carotenoids from natural as well as food samples was developed. Quantitative profiling of carotenoid compounds was carried out on three edible brown seaweeds (Sargassum horneri, Cystoseira hakodatensis, and Undaria pinnatifida) and three red seaweeds (Gracilaria vermiculophylla, Grateloupia asiatica, and Grateloupia livida). Fucoxanthin (Fx) was detected in all the brown seaweeds with quantities (mg g^?1 dry weight [dwt]) ranging from 1.3 ± 0.3 in C. hakodatensis to 2.4 ± 0.1 in S. horneri. U. pinnatifida, commonly known as wakame, had a Fx content of 2.3 ± 0.1 mg g^?1 dwt. In the case of red seaweeds, zeaxanthin (Zx) was the major carotenoid, and G. vermiculophylla had the highest Zx content (80.2 μg g^?1 dwt) among the red seaweeds apart from small amounts of Fx (9.1 μg g^?1 dwt). Similarly, the other two species of red seaweeds, G. asiatica and G. livida, contained (μg g^?1 dwt) lutein (Lut), Fx, and Zx as the major carotenoids (G. asiatica: Lut 10.4, Fx 1.5, Zx 1.1; G. livida: Lut 9.3, Fx 3.5, Zx 1.0). The results suggest the usefulness of edible varieties (barring wakame) of seaweeds as dietary sources of carotenoids.     

Absorption and Toxicity of Copper and Zinc in Bean Plants Cultivated in Soil Treated with Chicken Manure

The interaction between copper, zinc, and chicken manure, whenadded to soil, was studied in a greenhouse setting. Coppersulfate and of zinc chloride at concentrations of 0.5 to 2.0mmol kg^-1 were added separately to pots containing 3.0 kgof dystrophic dark red latosoil (LEd) plus 1,0% (m/m) pH 4.2chicken manure. IAPAR 57 beans were used as test plant andcultivated in the experimental soils for 30 days. Plant growthin terms of dry weight and the concentrations of copper and zincin the aerial part of the plants were determined. Bean plantingswere repeated four times, at four-month intervals. A 20%decrease in dry weight was observed when amounts of copper orzinc equal to or geater than 1.0 or 2.0 mmol kg^-1, respectively, were applied to the soil over an average of fourplantings. For these concentrations, the average amount of metalfound in the plant was 13.4 mg kg^-1 for copper and 224.8 mgkg^-1 for zinc. Chlorosis of the leaves in the bean plantswas also observed. The copper and zinc concentrations in thetreated soil were determined using different extractants. Amongthe solutions evaluated for the extraction of available zinc,1.0 M ammonium acetate, pH 4.8, showed a better correlation withthe metal concentration in the plant. As for copper, the bestcorrelation was found with the Mehlich-1 extractant.     

Antibody response to Newcastle disease virus (NDV) of recombinant fowlpox virus (FPV) expressing a hemagglutinin-neuraminidase of NDV into chickens in the presence of antibody to NDV or FPV.

Antibody response of recombinant fowlpox virus (FPV) was studied in chickens inoculated with the virus in the presence or absence of antibodies against Newcastle disease virus (NDV) or FPV. In the case of NDV, high hemagglutination-inhibition titers to NDV were obtained when the antibody was present. No immune response to NDV was observed in the chickens previously vaccinated with FPV.