Showing papers by "Universidade Federal de Viçosa published in 2009"

Above- and below-ground net primary productivity across ten Amazonian forests on contrasting soils

Abstract: The net primary productivity (NPP) of tropi- cal forests is one of the most important and least quan- tified components of the global carbon cycle. Most rel- evant studies have focused particularly on the quantifica- tion of the above-ground coarse wood productivity, and lit- tle is known about the carbon fluxes involved in other el- ements of the NPP, the partitioning of total NPP between its above- and below-ground components and the main en- vironmental drivers of these patterns. In this study we quantify the above- and below-ground NPP of ten Amazo- nian forests to address two questions: (1) How do Ama- zonian forests allocate productivity among its above- and below-ground components? (2) How do soil and leaf nu- trient status and soil texture affect the productivity of Ama- zonian forests? Using a standardized methodology to mea- sure the major elements of productivity, we show that NPP varies between 9.3±1.3 Mg C ha 1 yr 1 (mean±standard er- ror), at a white sand plot, and 17.0±1.4 Mg C ha 1 yr 1 at a very fertile Terra Preta site, with an overall average of 12.8±0.9 Mg C ha 1 yr 1 . The studied forests allocate on average 64±3% and 36±3% of the total NPP to the above- and below-ground components, respectively. The ratio of above-ground and below-ground NPP is almost invariant with total NPP. Litterfall and fine root production both in- crease with total NPP, while stem production shows no over- all trend. Total NPP tends to increase with soil phospho- rus and leaf nitrogen status. However, allocation of NPP to below-ground shows no relationship to soil fertility, but ap- pears to decrease with the increase of soil clay content.

HOMA1-IR and HOMA2-IR indexes in identifying insulin resistance and metabolic syndrome: Brazilian Metabolic Syndrome Study (BRAMS)

Abstract: OBJECTIVE: To investigate cut-off values for HOMA1-IR and HOMA2-IR to identify insulin resistance (IR) and metabolic syndrome (MS), and to assess the association of the indexes with components of the MS. METHODS: Nondiabetic subjects from the Brazilian Metabolic Syndrome Study were studied (n = 1,203, 18 to 78 years). The cut-off values for IR were determined from the 90th percentile in the healthy group (n = 297) and, for MS, a ROC curve was generated for the total sample. RESULTS: In the healthy group, HOMA-IR indexes were associated with central obesity, triglycerides and total cholesterol (p 2.7 and HOMA2-IR > 1.8; and, for MS were: HOMA1-IR > 2.3 (sensitivity: 76.8%; specificity: 66.7%) and HOMA2-IR > 1.4 (sensitivity: 79.2%; specificity: 61.2%). CONCLUSION: The cut-off values identified for HOMA1-IR and HOMA2-IR indexes have a clinical and epidemiological application for identifying IR and MS in Westernized admixtured multi-ethnic populations.

Intake and digestibility in cattle fed low-quality tropical forage and supplemented with nitrogenous compounds

Abstract: The objective of this study was to evaluate the effects of supplementation with nitrogenous compounds on intake, digestibility, and rumen microbial synthesis in cattle fed low-quality tropical forage. Five crossbred heifers, averaging 209 kg and fitted with ruminal fistulla, were used. The animals were fed ad libitum with signal grass (Brachiaria decumbens Stapf.) hay, which had crude protein (CP) content of 5.08%, as dry matter (DM) basis. The five treatments were defined according to the increasing level of CP in the diet (0, 3, 5, 7, and 9 percentile points above the forage CP level). The supplement consisted of the following nitrogen sources: urea, ammonium sulfate and albumin (4.5:0.5:1.0, respectively). The experiment was carried out according to a 5 × 5 Latin square design, with five experimental periods. The average CP levels in the diets were: 5.28, 8.08, 9.82, 11.87, and 13.63% on DM basis. The intakes of DM, organic matter (OM), and neutral detergent fiber (NDF) showed a quadratic response according to CP levels in the diet, with maximum responses at 10.83%, 10.78%, and 10.37% CP, respectively. The digestibility coefficients of OM and NDF showed a linear-response-plateau response according to CP levels, with the plateau beginning (maximum response) at 7.93% and 7.55% CP, respectively. The average daily concentration of rumen ammonia nitrogen (RAN) was positively related with CP levels. The RAN estimate associated with the maximum DM intake was 15.33 mg/dL. It was observed that intestinal flow of microbial nitrogenous compounds and nitrogen intake became equivalent to each other at 7.13% of CP.

The ER luminal binding protein (BiP) mediates an increase in drought tolerance in soybean and delays drought-induced leaf senescence in soybean and tobacco

Abstract: The ER-resident molecular chaperone BiP (binding protein) was overexpressed in soybean. When plants growing in soil were exposed to drought (by reducing or completely withholding watering) the wild-type lines showed a large decrease in leaf water potential and leaf wilting, but the leaves in the transgenic lines did not wilt and exhibited only a small decrease in water potential. During exposure to drought the stomata of the transgenic lines did not close as much as in the wild type, and the rates of photosynthesis and transpiration became less inhibited than in the wild type. These parameters of drought resistance in the BiP overexpressing lines were not associated with a higher level of the osmolytes proline, sucrose, and glucose. It was also not associated with the typical drought-induced increase in root dry weight. Rather, at the end of the drought period, the BiP overexpressing lines had a lower level of the osmolytes and root weight than the wild type. The mRNA abundance of several typical drought-induced genes [NAC2, a seed maturation protein (SMP), a glutathione-S-transferase (GST), antiquitin, and protein disulphide isomerase 3 (PDI-3)] increased in the drought-stressed wild-type plants. Compared with the wild type, the increase in mRNA abundance of these genes was less (in some genes much less) in the BiP overexpressing lines that were exposed to drought. The effect of drought on leaf senescence was investigated in soybean and tobacco. It had previously been reported that tobacco BiP overexpression or repression reduced or accentuated the effects of drought. BiP overexpressing tobacco and soybean showed delayed leaf senescence during drought. BiP antisense tobacco plants, conversely, showed advanced leaf senescence. It is concluded that BiP overexpression confers resistance to drought, through an as yet unknown mechanism that is related to ER functioning. The delay in leaf senescence by BiP overexpression might relate to the absence of the response to drought.

Changes in tree and liana communities along a successional gradient in a tropical dry forest in south-eastern Brazil

Abstract: We investigated changes in species composition and structure of tree and liana communities along a successional gradient in a seasonally dry tropical forest. There was a progressive increase in tree richness and all tree structural traits from early to late stages, as well as marked changes in tree species composition and dominance. This pattern is probably related to pasture management practices such as ploughing, which remove tree roots and preclude regeneration by resprouting. On the other hand, liana density decreased from intermediate to late stages, showing a negative correlation with tree density. The higher liana abundance in intermediate stage is probably due to a balanced availability of support and light availability, since these variables may show opposite trends during forest growth. Predicted succession models may represent extremes in a continuum of possible successional pathways strongly influenced by land use history, climate, soil type, and by the outcomes of tree–liana interactions.

Saúde da família: desafios no processo de reorientação do modelo assistencial

Abstract: The Family Health Program (PSF) constitutes a strategy for reformulating the health assistance model in Brazil. This study was carried out to ponder over the challenges of this strategy concerning to health practices in the primary care context. After existing for more than twelve years, there appear questionings related to the paper of PSF in the reformulation of the way to think and promote health, and their structures remain permeable to the traditional hegemonic model that corrupts the daily work process. Some changes and reconstruction are necessary in the health practices concerning to care production based on light, relational and integrate technologies that are centered on users' needs. Although the deconstruction/reconstruction process implicates much labor, the advantage in overcoming the challenges faced by PSF rather leads to the transformation of reality and to construction of health practices that are solidary, welcoming, and resolvent.

Optimization of methodology to analyze ascorbic and dehydroascorbic acid in vegetables

Abstract: In this study, different solutions to extract vitamin C were tested. High-performance liquid chromatography was chosen and the conditions were based on isocratic elution in reverse phase column. Dehydroascorbic acid was determined indirectly after its reduction using dithiothreitol. The use of metaphosphoric acid to stabilize the vitamin C was shown to be required and it was necessary to neutralize the pH of the extract to apply dithiothreitol. The average recovery was 90% in collard and tomato samples. The presence of oil did not interfere in extraction and the methodology can be used to analyze stir fried vegetables.

High-efficiency Agrobacterium-mediated transformation of citrus via sonication and vacuum infiltration.

Abstract: An improved method for the Agrobacterium infiltration of epicotyl segments of ‘Pineapple’ sweet orange [Citrus sinensis (L.) Osbeck] and ‘Swingle’ citrumelo [Citrus paradisi Macf. X Poncirus trifoliata (L.) Raf.] was developed in order to increase transformation frequency. Sonication-assisted Agrobacterium-mediated transformation (SAAT), vacuum infiltration, and a combination of the two procedures were compared with conventional Agrobacterium-mediated inoculation method (‘dipping’ method). It was observed that the morphogenic potential of the epicotyl segments decreased as the duration of SAAT and vacuum treatments increased. Transient GUS expression was not affected by the different SAAT treatments, but it was significantly enhanced by the vacuum infiltration treatments. The highest transformation efficiencies were obtained when the explants were subjected to a combination of SAAT for 2 s followed by 10 min of vacuum infiltration. PCR and Southern blot analysis of the uidA gene were used to confirm the integration of the transgenes. The transformation frequencies achieved in this study (8.4% for ‘Pineapple’ sweet orange and 11.2% for ‘Swingle’ citrumelo) are the highest ones reported for both cultivars.

Phylogeny and taxonomy of obscure genera of microfungi

Abstract: The recently generated molecular phylogeny for the kingdom Fungi, on which a new classification scheme is based, still suffers from an under representation of numerous apparently asexual genera of microfungi. In an attempt to populate the Fungal Tree of Life, fresh samples of 10 obscure genera of hyphomycetes were collected. These fungi were subsequently established in culture, and subjected to DNA sequence analysis of the ITS and LSU nrRNA genes to resolve species and generic questions related to these obscure genera. Brycekendrickomyces (Herpotrichiellaceae) is introduced as a new genus similar to, but distinct from Haplographium and Lauriomyces. Chalastospora is shown to be a genus in the Pleosporales, with two new species, C. ellipsoidea and C. obclavata, to which Alternaria malorum is added as an additional taxon under its oldest epithet, C. gossypii. Cyphellophora eugeniae is newly described in Cyphellophora (Herpotrichiellaceae), and distinguished from other taxa in the genus. Dictyosporium is placed in the Pleosporales, with one new species, D. streliziae. The genus Edenia, which was recently introduced for a sterile endophytic fungus isolated in Mexico, is shown to be a hyphomycete (Pleosporales) forming a pyronellea-like synanamorph in culture. Thedgonia is shown not to represent an anamorph of Mycosphaerella, but to belong to the Helotiales. Trochophora, however, clustered basal to the Pseudocercospora complex in the Mycosphaerellaceae, as did Verrucisporota. Vonarxia, a rather forgotten genus of hyphomycetes, is shown to belong to the Herpotrichiellaceae and Xenostigmina is confirmed as synanamorph of Mycopappus, and is shown to be allied to Seifertia in the Pleosporales. Dichotomous keys are provided for species in the various genera treated. Furthermore, several families are shown to be polyphyletic within some orders, especially in the Capnodiales, Chaetothyriales and Pleosporales.

Rumen dynamics of neutral detergent fiber in cattle fed low-quality tropical forage and supplemented with nitrogenous compounds

Abstract: The aim of this work was to evaluate the effects of supplementation with nitrogenous compounds on rumen dynamics of neutral detergent fiber (NDF) in cattle fed low-quality tropical forage. Five crossbred heifers with average live weight of 180 kg and fitted with rumen cannulae were used. The animals were fed ad libitum with signal grass (Brachiaria decumbens Stapf.) hay, which had crude protein (CP) content of 4.86% of dry matter (DM). The five treatments were proposed in order to raise the CP level of diets to 0, 2, 4, 6, and 8 percentile points above the CP level of the forage. The supplement was a mixture of urea, ammonium sulfate, and albumin (4.5:0.5:1.0, respectively). The experiment was carried out according to a 5 × 5 Latin square design, with five experimental periods. The average CP levels in the diets were: 5.19, 7.11, 8.60, 11.67, and 13.02% on DM basis. The potentially degradable NDF was linearly increased according to the CP levels in diet up to 6.97% of CP. From this point, there was stabilization of estimates (47.87% of NDF). The degradation rate of potentially degradable NDF was linearly increased with the CP levels in diets. The rumen flow of fibrous particles (L) showed a linear-response-plateau pattern according to the CP levels in diets. The plateau (maximum estimate) began on 7.24% of CP. The mean retention time in the rumen and the rumen fill effect of undegradable NDF were affect by the CP levels similarly to L, with plateau (minimum) beginning on 6.90 and 6.97% of CP, respectively.

Wild Brazilian mustard (Brassica juncea L.) seed oil methyl esters as biodiesel fuel.

Abstract: Wild mustard (Brassica juncea L.) oil is evaluated as a feedstock for biodiesel production. Biodiesel was obtained in 94 wt.% yield by a standard transesterification procedure with methanol and sodium methoxide catalyst. Wild mustard oil had a high content of erucic (13(Z)-docosenoic; 45.7 wt.%) acid, with linoleic (9(Z),12(Z)-octadecadienoic; 14.2 wt.%) and linolenic (9(Z),12(Z),15(Z)-octadecatrienoic; 13.0 wt.%) acids comprising most of the remaining fatty acid profile. The cetane number, kinematic viscosity, and oxidative stability (Rancimat method) of the methyl esters was 61.1, 5.33 mm2 s−1 (40 °C) and 4.8 h (110 °C), respectively. The cloud, pour and cold filter plugging points were 4, −21 and −3 °C, respectively. Other properties such as acid value, lubricity, free and total glycerol content, iodine value, Gardner color, specific gravity, as well as sulfur and phosphorous contents were also determined and are discussed in light of biodiesel standards ASTM D6751 and EN 14214. Also reported are the properties and composition of wild mustard oil, along with identification of wild mustard collected in Brazil as Brassica juncea L. (2n = 36) as opposed to the currently accepted Sinapis arvensis L. (2n = 18) classification. In summary, wild mustard oil appears to be an acceptable feedstock for biodiesel production.

A diallel study of yield components and fruit quality in chilli pepper (Capsicum baccatum)

Abstract: The aim of this work was to estimate the general and specific combining ability of peppers by measuring fruit quality and yield traits. This experiment was carried out on the garden field from Universidade Federal de Vicosa (UFV), Minas Gerais State—Brazil. Eight lines of Capsicum baccatum belonging to the UFV Horticultural Germplasm Bank were chosen based on their broad genetic and phenotypical background variation and then they were crossed in a complete diallel way. The F1 seeds of the 56 hybrids and eight parents were planted in the field in a randomized complete block design. The data were submitted to ANOVA and the means were grouped by Scott–Knott test (P ≤ 0.01). Significant variation for fruit quality and yield components was observed among parents and F1 generation. Analysis of variance for the combining ability showed that GCA effects exhibited significant difference and SCA effects of the crosses were significant, except for the height of first bifurcation. For almost all characters both additive and non-additive effects influenced the performance of hybrids.

Chemical, physical and micromorphological properties of termite mounds and adjacent soils along a toposequence in Zona da Mata, Minas Gerais State, Brazil

Abstract: article i nfo Little is known about the effects of neotropical mound-building termites in soil chemical and physical properties. The influence of soil termite activity on soil characteristics was studied by assessing chemical, physical and micromorphological properties of a toposequence of Latosols (Oxisols). Soil samples were collected from the walls and inner parts of termite mounds and also from adjacent soil. A high diversity of termite genera was found in the mounds along the toposequence, together with the inquiline termites and other soil-dwelling arthropods. Chemical analyses showed that pH and the contents of organic C and N, P, Ca and Mg were significantly higher in termite mounds compared with adjacent areas, with an inverse trend for Al content. Significant differences in pH and exchangeable Al were observed between soil and mound across the slopes. The mound density across the landscape was higher at the upper slope segment, followed by the hill top, middle slope and lower slope segments. Considering a lifespan of 30 years and dimensions of termite mounds found in the toposequence we conclude that the textural and chemical uniformity of Latosols may be increased, following the pedobiological turnover during mound building, with local rates varying from 2.1 to 7.5 m 3 ha �1 .

Óleo de copaíba (Copaifera sp.): histórico, extração, aplicações industriais e propriedades medicinais

Abstract: Este trabalho teve como objetivo realizar uma revisao de literatura sobre o genero Copaifera sp. Foi realizado levantamento bibliografico do periodo de 1792 a 2008 utilizando bibliotecas da Universidade de Sao Paulo, Universidade Federal de Vicosa, Universidade Federal de Alfenas e Universidade Jose do Rosario Vellano, pesquisas as bases de dados SCOPUS e PubMed, alem de ferramentas de busca na web. Utilizou-se para a busca palavras chave como "Copaiba", "Copaifera", "Copaiba oil" "Oleo de Copaiba". Como resultado desta pesquisa obteve-se a selecao de 63 referencias incluindo livros, artigos, cadernos tecnicos, resumos de congressos, teses, dissertacoes e patentes. Estes dados apontaram o oleo de copaiba como um exsudato produzido pelas copaibeiras como defesa contra seus predadores, que vem sendo utilizado pela medicina tradicional popular e silvicola ha mais de 500 anos. Ele e extraido destas arvores atraves de perfuracoes realizadas em seus troncos. Alem das inumeras aplicacoes do oleo em cosmeticos e outras industrias, ainda ha uma serie de indicacoes para seu uso na medicina. Existem hoje descritas algumas dezenas de propriedades medicinais diferentes, que vem sendo em alguns casos comprovadas cientificamente, como atividade antimicrobiana, antiinflamatoria, anti-neoplasica entre outras. Estudos recentes tem demonstrado tambem grande potencial de uso do oleo de copaiba na odontologia, na composicao de cimentos endodonticos e na prevencao e combate da doenca periodontal. As informacoes contidas neste trabalho demonstram uma grande variabilidade de aplicacoes do oleo de copaiba. Entretanto uma quantidade limitada de pesquisas sobre suas propriedades medicinais tem sido realizada, apresentando assim a necessidade de novas pesquisas sobre estas.

A práxis do agente comunitário de saúde no contexto do programa saúde da família: reflexões estratégicas

Abstract: O Programa Saude da Familia (PSF) surgiu no cenario brasileiro como estrategia de superacao do modelo assistencial centrado na doenca e no cuidado medico individualizado. Nesse contexto, os agentes comunitarios de saude (ACS) tem sido considerados atores-chave na implantacao de politicas voltadas para a reorientacao do modelo de atencao a saude. O objetivo deste estudo foi analisar as concepcoes e percepcoes sobre o SUS e o PSF que norteiam as acoes dos ACS, refletindo sobre sua funcao e formacao profissional. O trabalho fundamentou-se na pesquisa quali-quantitativa, foi realizado em Cajuri-MG e foram entrevistados todos os ACS (n=11) que trabalhavam no PSF. Os resultados demonstraram que a maioria dos ACS (72,7%) residia na comunidade em que atuava, trabalhava ha mais de cinco anos no PSF e acompanhava a quantidade de familias recomendada. Entre as principais funcoes, destacaram-se visitas domiciliares, busca ativa e educacao em saude, que na maioria das vezes acontecia de forma individualizada e centrada no reforco da assistencia medica e na prevencao de riscos especificos. Em relacao a capacitacao, 54,6% dos ACS receberam orientacao antes de iniciar o trabalho e 81,8% participaram de cursos depois que ja estavam trabalhando. Apenas 27,3% dos ACS souberam conceituar o SUS e 36,4% demonstraram entendimento adequado sobre PSF. Esses resultados demonstram a necessidade de maiores esforcos para melhorar a capacitacao do ACS, visando adequar seu nivel de apreensao e conhecimento dos principios do SUS e PSF, para que ele possa atuar segundo as diretrizes desse sistema e contribuir efetivamente para sua consolidacao.

Collaboration intensity in the Brazilian supermarket retail chain

Abstract: Purpose – This paper seeks to identify collaboration elements and evaluate their intensity in the Brazilian supermarket retail chain, especially the manufacturer‐retailer channel.Design/methodology/approach – A structured questionnaire was elaborated and applied to 125 representatives from suppliers of large supermarket chains. Statistical methods including multivariate analysis were employed. Variables were grouped and composed into five indicators (joint actions, information sharing, interpersonal integration, gains and cost sharing, and strategic integration) to assess the degree of collaboration.Findings – The analyses showed that the interviewees considered interpersonal integration to be of greater importance to collaboration intensity than the other integration factors, such as gain or cost sharing or even strategic integration.Research limitations/implications – The research was conducted solely from the point of view of the industries that supply the large retail networks. The interviews were not...

Learning of Chemical Equilibrium through Modelling‐based Teaching

Abstract: This paper presents and discusses students’ learning process of chemical equilibrium from a modelling‐based approach developed from the use of the ‘Model of Modelling’ diagram. The investigation was conducted in a regular classroom (students 14–15 years old) and aimed at discussing how modelling‐based teaching can contribute to students learning about the main qualitative aspects concerning chemical equilibrium. The data (collected from the written material produced by the students and the video‐recording of the classes) were organised in case studies for each group of students. The discussion supports the conclusion that elements from the ‘Model of Modelling’ diagram, as well as methodological aspects related to the teacher’s action, influenced the students’ learning process.