Carboxy-fluorescein diacetate, succinimidyl ester labeled papillomavirus virus-like particles fluoresce after internalization and interact with heparan sulfate for binding and entry

Human papillomaviruses (HPVs) infect epithelial cells and are associated with genital carcinoma. Most epithelial cell lines express cell-surface glycosaminoglycans (GAGs) usually found attached to the protein core of proteoglycans. Our aim was to study how GAGs influenced HPV entry. Using a human keratinocyte cell line (HaCaT), preincubation of HPV virus-like particles (VLPs) with GAGs showed a dose-dependent inhibition of binding. The IC50 (50% inhibition) was only 0.5 mug/ml for heparin, 1 mug/ml for dextran sulfate, and 5-10 mug/ml for heparan sulfate from mucosal origin. Mutated chinese hamster ovary (CHO) cell lines lacking heparan sulfate or all GAGs were unable to bind HPV VLPs. Here we also report a method to study internalization by using VLPs labeled with carboxy-fluorescein diacetate, succinimidyl ester, a fluorochrome that is only activated after cell entry. Pretreatment of labeled HPV VLPs with heparin inhibited uptake, suggesting a primary interaction between HPV and cell-surface heparan sulfate. (C) 2003 Elsevier Science (USA). All rights reserved.

Chemical and biochemical properties of Araucaria angustifolia (Bert.) Ktze. forest soils in the state of São Paulo

Araucaria angustifolia, commonly named Araucaria, is a Brazilian native species that is intensively exploited due to its timber quality. Therefore, Araucaria is on the list of species threatened by extinction. Despite the importance of soil for forest production, little is known about the soil properties of the highly fragmented Araucaria forests. This study was designed to investigate the use of chemical and biological properties as indicators of conservation and anthropogenic disturbance of Araucaria forests in different sampling periods. The research was carried out in two State parks of São Paulo: Parque Estadual Turístico do Alto do Ribeira and Parque Estadual de Campos de Jordão. The biochemical properties carbon and nitrogen in microbial biomass (MB-C and MB-N), basal respiration (BR), the metabolic quotient (qCO2) and the following enzyme activities: β-glucosidase, urease, and fluorescein diacetate hydrolysis (FDA) were evaluated. The sampling period (dry or rainy season) influenced the results of mainly MB-C, MB-N, BR, and qCO2. The chemical and biochemical properties, except K content, were sensitive indicators of differences in the conservation and anthropogenic disturbance stages of Araucaria forests. Although these forests differ in biochemical and chemical properties, they are efficient in energy use and conservation, which is shown by their low qCO2, suggesting an advanced stage of succession.

MICROBIAL CHARACTERISTICS OF SOILS UNDER AN INTEGRATED CROP-LIVESTOCK SYSTEM

Integrated crop-livestock systems (ICLs) are a viable strategy for the recovery and maintenance of soil characteristics. In the present study, an ICL experiment was conducted by the Instituto Agronômico do Paraná in the municipality of Xambre, Parana (PR), Brazil, to evaluate the effects of various grazing intensities. The objective of the present study was to quantify the levels of microbial biomass carbon (MBC) and soil enzymatic activity in an ICL of soybean (summer) and Brachiaria ruziziensis (winter), with B. ruziziensis subjected to various grazing intensities. Treatments consisted of varying pasture heights and grazing intensities (GI): 10, 20, 30, and 40 cm (GI-10, GI-20, GI-30, and GI-40, respectively) and a no grazing (NG) control. The microbial characteristics analysed were MBC, microbial respiration (MR), metabolic quotient (qCO2), the activities of acid phosphatase, β-glucosidase, arylsuphatase, and cellulase, and fluorescein diacetate (FDA) hydrolysis. Following the second grazing cycle, the GI-20 treatment (20-cm - moderate) grazing intensity) contained the highest MBC concentrations and lowest qCO2 concentrations. Following the second soybean cycle, the treatment with the highest grazing intensity (GI-10) contained the lowest MBC concentration. Soil MBC concentrations in the pasture were favoured by the introduction of animals to the system. High grazing intensity (10-cm pasture height) during the pasture cycle may cause a decrease in soil MBC and have a negative effect on the microbial biomass during the succeeding crop. Of all the enzymes analyzed, only arylsuphatase and cellulase activities were altered by ICL management, with differences between the moderate grazing intensity (GI-20) and no grazing (NG) treatments.

Fusarium oxysporum strains as biocontrol agents against Fusarium wilt: effects on soil microbial biomass and activity

Before planning the large-scale use of nonpathogenic strains of Fusarium oxysporum as biocontrol agents of Fusarium wilt, their behaviour and potential impact on soil ecosystems should be carefully studied as part of risk assessment. The aim of this work was to evaluate the effects of antagonistic F. oxysporum strains, genetically manipulated (T26/6) or not (233/1), on soil microbial biomass and activity. The effects were evaluated, in North-western Italy, in two soils from different sites at Albenga, one natural and the other previously solarized, and in a third soil obtained from a 10-year-old poplar stand (Popolus sp.), near Carignano. There were no detectable effects on ATP, fluorescein diacetate hydrolysis, and biomass P that could be attributed to the introduction of the antagonists. A transient increase of carbon dioxide evolution and biomass C was observed in response to the added inoculum. Although the results showed only some transient alterations, further studies are required to evaluate effects on specific microorganism populations.

Use of an artificial root to examine the influence of 8-hydroxyquinoline on soil microbial activity and bacterial community structure

Invasive plant species have been shown to alter the microbial community composition of the soils they invade and it is suggested that this below-ground perturbation of potential pathogens, decomposers or symbionts may feedback positively to allow invasive success. Whether these perturbations are mediated through specific components of root exudation are not understood. We focussed on 8-hydroxyquinoline, a putative allelochemical of Centaurea diffusa (diffuse knapweed) and used an artificial root system to differentiate the effects of 8-hydroxyquinoline against a background of total rhizodeposition as mimicked through supply of a synthetic exudate solution. In soil proximal (0-10 cm) to the artificial root, synthetic exudates had a highly significant (P < 0.001) influence on dehydrogenase, fluorescein diacetate hydrolysis and urease activity. in addition, 8-hydroxyquinoline was significant (p = 0.003) as a main effect on dehydrogenase activity and interacted with synthetic exudates to affect urease activity (p = 0.09). Hierarchical cluster analysis of 16S rDNA-based DGGE band patterns also identified a primary affect of synthetic exudates and a secondary affect of 8-hydroxyquinoline on bacterial community structure. Thus, we show that the artificial rhizosphere produced by the synthetic exudates was the predominant effect, but, that the influence of the 8-hydroxyquinoline signal on the activity and structure of soil microbial communities could also be detected. (C) 2009 Elsevier Ltd. All rights reserved.

Efeito de casca de camarão, hidrolisado de peixe e quitosana no controle da murcha de Fusarium oxysporum f.sp. chrysanthemi em crisântemo

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Características biológicas do solo indicadoras de qualidade após dois anos de aplicação de biossólido industrial e cultivo de milho

A utilização agrícola de biossólidos tem sido muito incentivada, mas, como esses resíduos apresentam composição química variada, o valor agronômico e os efeitos sobre características indicadoras de qualidade do solo precisam ser avaliados caso a caso, a fim de estabelecer normas de segurança para uso desses materiais. Neste trabalho foram avaliadas características biológicas, após a aplicação, por dois anos consecutivos, de doses crescentes (0, 6, 12, 18 e 24 t ha-1 base seca) de um biossólido gerado por uma indústria de fibras e resinas PET e da adubação mineral completa no cultivo de milho, em um Cambissolo distrófico, comparados aos de uma área adjacente, sob Brachiaria sp. e sem cultivo nos últimos 10 anos, usada como referência. Os valores de C e N da biomassa microbiana, a respiração basal e as atividades das enzimas urease e beta-glicosidase e da hidrólise do diacetato de fluoresceína (FDA) aumentaram, enquanto a atividade da fosfatase ácida diminuiu com a elevação das doses de biossólido, porém estas não tiveram efeito sobre o quociente metabólico (qCO2). A diminuição da atividade da fosfatase se deveu ao aumento da disponibilidade de P no solo, não caracterizando efeito adverso da aplicação do biossólido. Com aplicação de 12 t ha-1 de biossólido (recomendação agronômica), a respiração e a hidrólise da FDA foram maiores e a atividade da fosfatase foi menor que a obtida no solo com adubação mineral, mas as demais características avaliadas não diferiram entre estes tratamentos. A colonização micorrízica de Brachiaria sp. não diferiu entre plantas de crescimento espontâneo nas parcelas anteriormente cultivadas com milho e aquelas da área adjacente. Apesar do menor número de esporos, verificou-se enriquecimento de espécies de fungos micorrízicos arbusculares (FMAs) nas parcelas cultivadas. O carbono orgânico (Corg) e a biomassa microbiana apresentaram alta correlação com os demais parâmetros avaliados, indicando que as alterações na quantidade e qualidade da matéria orgânica, promovidas pela aplicação do biossólido, refletiram na dinâmica da microbiota e influenciaram positivamente os parâmetros biológicos de qualidade do solo.

Efeito de fontes de matéria orgânica sobre a ferrugem em mudas de cafeeiro

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Evolução de CO2 e atividades enzimáticas em amostras de solo tratado com herbicidas

Effects of bentazon, metolachlor, trifluralin, imazethapyr, imazethapyr+lactofen, haloxyfop-methyl, glyphosate and chlorimuron-ethyl at rates of 2 and 10 times the equivalent commercial dose on soil microbial activity was evaluated in soil samples extracted from a field never treated before. Global soil microbe respiration, estimated by CO2 production at 2, 4, 8, 12, 16, 20, 24 and 28 days of soil incubation and enzymatic activities (dehydrogenase and fluorescein diacetate hydrolysis) at 8 and 28 days were used as bioindicators. Bentazon and mixture imazethapyr+lactofen at the highest rate and haloxyfop-methyl at both rates, inhibited soil respiration although with differences in timing and duration. None of the herbicides affected FDA hydrolysis. Dehydrogenase activity was inhibited at 8 days of incubation with bentazon and imazethapyr at high rates but it was stimulated by metolachlor and imazethapyr at low rate and glyphosate at the highest rate. Herbicide effects on soil microbial activity was detected with higher sensitivity by global soil microbe respiration and dehydrogenase activity than by FDA hydrolysis. Only dehydrogenase activity and soil respiration estimations at 8 days of soil incubation had significant correlation. Results indicated the need of multiple estimations when evaluating herbicides effects on soil microbiota

CHEMICAL AND BIOCHEMICAL PROPERTIES OF ARAUCARIA ANGUSTIFOLIA (BERT.) KTZE. FOREST SOILS IN THE STATE OF SAO PAULO

Araucaria angustifolia, commonly named Araucaria, is a Brazilian native species that is intensively exploited due to its timber quality. Therefore, Araucaria is on the list of species threatened by extinction. Despite the importance of soil for forest production, little is known about the soil properties of the highly fragmented Araucaria forests. This study was designed to investigate the use of chemical and biological properties as indicators of conservation and anthropogenic disturbance of Araucaria forests in different sampling periods. The research was carried out in two State parks of Sao Paulo: Parque Estadual Turistico do Alto do Ribeira and Parque Estadual de Campos de Jordao. The biochemical properties carbon and nitrogen in microbial biomass (MB-C and MB-N), basal respiration (BR), the metabolic quotient (qCO(2)) and the following enzyme activities: beta-glucosidase, urease, and fluorescein diacetate hydrolysis (FDA) were evaluated. The sampling period (dry or rainy season) influenced the results of mainly MB-C, MB-N, BR, and qCO(2). The chemical and biochemical properties, except K content, were sensitive indicators of differences in the conservation and anthropogenic disturbance stages of Araucaria forests. Although these forests differ in biochemical and chemical properties, they are efficient in energy use and conservation, which is shown by their low qCO(2), suggesting an advanced stage of succession.

Chemical and biochemical properties of Araucaria angustifolia (Bert.) Ktze. forest soils in the state of São Paulo

Araucaria angustifolia, commonly named Araucaria, is a Brazilian native species that is intensively exploited due to its timber quality. Therefore, Araucaria is on the list of species threatened by extinction. Despite the importance of soil for forest production, little is known about the soil properties of the highly fragmented Araucaria forests. This study was designed to investigate the use of chemical and biological properties as indicators of conservation and anthropogenic disturbance of Araucaria forests in different sampling periods. The research was carried out in two State parks of São Paulo: Parque Estadual Turístico do Alto do Ribeira and Parque Estadual de Campos de Jordão. The biochemical properties carbon and nitrogen in microbial biomass (MB-C and MB-N), basal respiration (BR), the metabolic quotient (qCO2) and the following enzyme activities: β-glucosidase, urease, and fluorescein diacetate hydrolysis (FDA) were evaluated. The sampling period (dry or rainy season) influenced the results of mainly MB-C, MB-N, BR, and qCO2. The chemical and biochemical properties, except K content, were sensitive indicators of differences in the conservation and anthropogenic disturbance stages of Araucaria forests. Although these forests differ in biochemical and chemical properties, they are efficient in energy use and conservation, which is shown by their low qCO2, suggesting an advanced stage of succession.

Microbial and soil properties in restoration areas in the jequitinhonha valley, Minas Gerais

To mitigate the impacts of eucalypt monoculture, forestry companies in the Upper Jequitinhonha Valley (MG) have adopted the insertion of strips of native vegetation in-between the commercial plantations. The method used for the creation of these corridors is to allow spontaneous regrowth of native vegetation in areas previously under eucalypt. The objective of this study was to evaluate the effect of cover crops on microbial and soil properties for a detailed description of the restoration process of native vegetation in forest soils of the Jequitinhonha Valley. The treatments were represented by an initial restoration stage (< 4 years) with or without remaining eucalypt and the advanced restoration stage (> 4 years) with or without remaining eucalypt, plus the three controls: commercial eucalypt plantation, Cerrado vegetation and native forest. Soil samples were collected for three consecutive years in the dry and rainy season (August and February, respectively). The microbial activity, regardless of the presence of remaining eucalypt , did not differ among the restoration areas, except for the metabolic quotient (qCO2) in the rainy season of February 2007. At this time, this microbial activity was higher in the advanced restoration stage without eucalypt than initial restoration without eucalypt and advanced restoration with eucalypt. The restoration areas, in general, did not differ from the control: eucalypt plantation and Cerrado either. Compared to the forest, the levels of organic C, microbial C, basal respiration (Rbasal) and hydrolysis of fluorescein diacetate (FDA) in the restoration areas were, in general, lower and did not differ in qCO2 and microbial quotient (qMIC). In general, the soil quality was similar in the initial and advanced restoration stages. Most of the soil and microbial properties in the three years indicated that the restoration areas were most similar to the Cerrado. In the advanced restoration areas without eucalypt compared to Cerrado, the lower Rbasal in the 3rd year and the lower FDA and qMIC and higher qCO2 in the 2nd year indicated that the removal of the remaining eucalypt trees was unfavorable for restoration.

Dried powders of velvetbean and pine bark added to soil reduce Rhizoctonia solani-induced disease on soybean

Diseases induced by Rhizoctonia solani, like damping-off and root and stem rot on soybean (Glycine max), are a serious problem around the world. The addition of some organic material to soil is an alternative control for these diseases. In this study, benzaldehyde and dried powders of kudzu (Pueraria lobata), velvetbean or mucuna (Mucuna deeringiana), and pine bark (Pinus spp.) were used in an attempt to improve soybean plant growth and to reduce the disease R. solani (AG-4) causes on soybean. Benzaldehyde (0.1-0.4 mL/kg of soil) and velvetbean (25-100 g/kg) significantly (P < 0.05) reduced mycelial growth of R. solani in laboratory tests. In greenhouse experiments, the percentage of non-diseased plants was higher in treatments with pine bark and velvetbean (50-100 g/kg). In soil treated with kudzu (r²=0.91) or velvetbean (r²=0.94), increasing rates of these amendments tended to increase plant fresh mass. In microplot field conditions, soil amended with velvetbean (r²=0.85) and pine-bark (r²=0.61) significantly reduced disease on soybean. Numbers of Bacillus megaterium (r²=0.87) and Trichoderma hamatum (r²=0.92) and hydrolysis of fluorescein diacetate (r²=0.91) were higher in soil amended with increasing rates of velvetbean, indicating an increase in microbial activity. From this study it is concluded that dried powders of velvetbean and pine bark added to soil can reduce Rhizoctonia-induced disease on soybean.

Biomassa microbiana e atividade enzimática em solos do Estado de São Paulo sob vegetação nativa e cultivados

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efeito de lodo de esgoto sobre a nutrição, nodulação e controle de doenças da soja

Pós-graduação em Agronomia (Proteção de Plantas) - FCA