Universidade Federal de Viçosa

About: Universidade Federal de Viçosa is a education organization based out in Viçosa, Brazil. It is known for research contribution in the topics: Population & Dry matter. The organization has 16012 authors who have published 26711 publications receiving 353416 citations.

Endogenous fraction and urinary recovery of purine derivatives obtained by different methods in Nellore cattle.

Abstract: Two experiments were conducted to assess the endogenous fraction of purine derivative (PD) excretion, urinary recovery, and intestinal digestibility of purines in Nellore heifers. For both experiments, 8 Nellore heifers fitted with ruminal and abomasal cannulas were allocated to two 4 × 4 Latin squares. The diets were based on corn silage and concentrate (60 and 40% DM basis, respectively); feces and urine samples were obtained by total collection, and abomasal DM flow was estimated using indigestible NDF as an internal marker. In Exp. I, 4 of the 8 heifers (BW 258 ± 20 kg) were also fitted with ileal cannula. The planned treatments were 4 different DMI: 1.2, 1.6, 2.0, and 2.4% of BW (DM basis). The endogenous losses and purine recovery as urinary PD were estimated using linear regression between daily urinary PD excretion (Y) and daily abomasal flow of purine bases (X), expressed in millimoles per kilogram of BW(0.75). In Exp. II, the same 8 Nellore heifers (BW of 296 ± 15 kg) were fed at 1.37% BW (DM basis). The treatments were the infusion of purines (RNA from torula yeast, type VI, Sigma) into the abomasum in increasing amounts (0, 33, 66, and 100 mmol/d). All statistical analyses were performed using the PROC MIXED procedure in SAS. In Exp. I, the DMI range was 1.16 to 1.84% of BW and did not affect (P > 0.05) the apparent RNA digestibility in the small intestine, which had a mean of 75.6%, and a true digestibility of 93.0%. The mean ratio of the N-RNA to the total-N in the ruminal bacteria was 0.137. The daily urinary PD excretion (Y, mmol/kg of BW(0.75)) was a function of RNA flow in the abomasum (X, mmol/kg of BW(0.75)): Y = 0.860X + 0.460, where 0.860 and 0.460 were the PD recovery of purines and the endogenous fraction (in mmol/kg of BW(0.75)), respectively. In Exp. II, the daily urinary PD excretion was a function of RNA flow in the abomasum: Y = 0.741X + 0.301, where 0.741 and 0.301 were the recovery of PD in urine of infused purines and the endogenous losses (in mmol/kg of BW(0.75)), respectively. In conclusion, our data suggest that in Nellore heifers the respective values of endogenous PD excretion (mmol/kg of BW(0.75)), urinary recovery of the purines absorbed in the abomasum, and true digestibility of RNA in the small intestine were 0.30, 0.80, and 0.93.

Impact and Selectivity of Insecticides to Predators and Parasitoids

Abstract: Problems with the use of insecticides has brought losses, such as, negative impact on natural enemies. When these beneficial insects reduce cause the eruption of pests and resurgence it’s more common. Thus principles of conservation these arthropods are extremely important in the biological natural control of pests, so that these enemies may present a high performance. Because of the negative impacts caused by insecticides on agriculture and their harmful effects on natural enemies, the objective of this article is to approach two important subjects, divided into three parts. Part I relates to the description of the main crop pests and their natural enemies; Part II involves the impact of insecticides on predators and parasitoids and Part III focuses on the selectivity of several groups of insecticides to natural enemies. Before spraying insecticides, it is necessary to choose a product that is efficient to pests and selective to natural enemies. So, it is indispensable to identify correctly the groups and species of natural enemies, since insecticides have an impact on their survival, growth, development, reproduction (sexual ratio, fecundity, longevity and fertility), and behavior (motility, orientation, feeding, oviposition and learning) of insects. The mechanisms of toxicity and selectivity of insecticides are related to the properties of higher or lower solubility and molecular weight. Besides, characteristics of the cuticular composition of the integument of natural enemies are extremely important in the selectivity of a product or the tolerance of a certain predator or parasitoid to this molecules. Impacto e Seletividade de Inseticidas para Predadores e Parasitoides Resumo. Dentre os problemas advindos do uso de inseticidas, a destruicao de inimigos naturais e fator importante. Estes insetos beneficos podem reduzir problemas de erupcao de pragas secundarias, ressurgencia de pragas e manter a praga abaixo do nivel de dano economico. Dessa forma a conservacao de inimigos naturais, para que os mesmos exercam alta performance frente as pragas, e de extrema importância em controle biologico de pragas. Metodo de controle essencial utilizados nos programas de manejo integrado de pragas. Tendo em vista os impactos negativos dos inseticidas na agricultura e os seus efeitos adversos sobre os inimigos naturais, este artigo visa abordar dois assuntos importantes, que para isso e dividido em tres partes. A parte I relacionada com o reconhecimento das principais pragas agricolas e seus inimigos naturais; a parte II envolve o impacto dos inseticidas sobre os predadores e parasitoides e a parte III abordara sobre a seletividade dos diversos grupos de inseticidas aos inimigos naturais. Antes de se pulverizar inseticida e necessario a escolha de um produto que seja seletivo e eficiente, assim torna-se imprescindivel identificar de forma correta os grupos e especies de inimigos naturais. Uma vez que os inseticidas apresentam impacto sobre a sobrevivencia, o crescimento e desenvolvimento, na reproducao (razao sexual, fecundidade, longevidade e fertilidade), no comportamento (mobilidade, orientacao, alimentacao, oviposicao e aprendizado). Os mecanismos de toxicidade e seletividade dos inseticidas estao relacionados as propriedades de maior ou menor solubilidade e peso molecular. Alem disso, caracteristicas da composicao cuticular do integumento dos inimigos naturais sao de extrema importância na seletividade de um produto ou a tolerância de determinado predador ou parasitoide.

Thermal decomposition and recovery properties of ZnAl–CO3 layered double hydroxide for anionic dye adsorption: insight into the aggregative nucleation and growth mechanism of the LDH memory effect.

Abstract: The thermal decomposition of carbonate-intercalated layered double hydroxide (ZnAl–CO3-LDH) and recovery induced by water and dye solution addition were studied in situ by time-resolved wide angle X-ray scattering (WAXS) and time-resolved X-ray absorption spectroscopy (XAS), providing insights into the mechanisms of these structural transformations. LDH nanostructure recovery was driven by an aggregative nucleation and growth mechanism, which is limited by the steric hindrance caused by the adsorption of the Acid Blue 113 azo dye (AB) on the external surface of both the nanocrystalline tactoids and the exfoliated layers. The recovery behaviour in dye solution is consistent with the hypothesis of the LDH-recovery by a direct synthesis process, generating nanosized LDH particles with thickness about four times lower than those induced by water addition. These findings explain the higher AB adsorption capacity (1587 mg g−1) of calcined LDH, compared to pristine ZnAl–CO3-LDH (261.8 mg g−1) and also the efficient recycling of the spent adsorbent.

Diurnal Oscillations of Soybean Circadian Clock and Drought Responsive Genes

Abstract: Rhythms produced by the endogenous circadian clock play a critical role in allowing plants to respond and adapt to the environment. While there is a well-established regulatory link between the circadian clock and responses to abiotic stress in model plants, little is known of the circadian system in crop species like soybean. This study examines how drought impacts diurnal oscillation of both drought responsive and circadian clock genes in soybean. Drought stress induced marked changes in gene expression of several circadian clock-like components, such as LCL1-, GmELF4- and PRR-like genes, which had reduced expression in stressed plants. The same conditions produced a phase advance of expression for the GmTOC1-like, GmLUX-like and GmPRR7-like genes. Similarly, the rhythmic expression pattern of the soybean drought-responsive genes DREB-, bZIP-, GOLS-, RAB18- and Remorin-like changed significantly after plant exposure to drought. In silico analysis of promoter regions of these genes revealed the presence of cis-elements associated both with stress and circadian clock regulation. Furthermore, some soybean genes with upstream ABRE elements were responsive to abscisic acid treatment. Our results indicate that some connection between the drought response and the circadian clock may exist in soybean since (i) drought stress affects gene expression of circadian clock components and (ii) several stress responsive genes display diurnal oscillation in soybeans.