Purification and biological effects of a C-type lectin isolated from Bothrops moojeni

Snake venom proteins from the C-type lectin family have very distinct biological activities despite their highly conserved primary structure, which is homologous to the carbohydrate recognition region of true C-type lectins. We purified a lectin-like protein (BmLec) from Bothrops moojeni venom and investigated its effect on platelet aggregation, insulin secretion, antibacterial activity, and isolated kidney cells. The BmLec was purified using two chromatographic steps: affinity chromatography and reverse phase high performance liquid chromatography (HPLC). BmLec showed a dose-dependent platelet aggregation and significantly decreased the bacterial growth rate in approximately 15%. During scanning electron microscopy, the profile of Xanthomonas axonopodis pv. passiflorae treated with lectin disclosed a high vesiculation and membrane rupture. BmLec induced a strong and significant increase in insulin secretion at 2.8 and 16.7 mM glucose concentrations, and this effect was seen in the presence of EGTA in both experiments. BmLec (10 mu g/mL) increased the perfusion pressure, renal vascular resistance and urinary flow. The glomerular filtration rate and percentages of sodium, potassium and chloride tubular transport were reduced at 60 minutes of perfusion. Renal alterations caused by BmLec were completely inhibited by indomethacin in all evaluated parameters. In conclusion, the C-type lectin isolated from Bothrops moojeni affected platelet aggregation, insulin secretion, antibacterial activity and isolated kidney function.

Método de melhoramento por descendência de semente única, para obtenção de linhagens de feijoeiro resistentes ao crestamento bacteriano comum.

O objetivo do presente trabalho foi a obtenção de linhagens de feijoeiro comum resistentes aos crestamento bacteriano comum, utilizando-se o método de melhoramento por descendência de semente única. Foram obtidas 30 linhagens com resistência ao crestamento bacteriano comum e uma considerável diminuição do tempo para o avanço das gerações.

Caracterização agronômica e fisíco-química de progênies de maracujazeiro azedo (Passiflora edulis Sims) no Distrito Federal

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Agronomia e Medicina Veterinária, Programa de Pós-Graduação em Agronomia, 2016.

Doenças em plantios jovens de eucalipto em sistemas agroflorestais no Acre.

O uso de sistemas agrossilvipastoris com plantio de eucalipto tem se tornado bastante importante no Acre. Com o aumento dos cultivos de eucalipto no Acre, tem ocorrido o ataque de patógenos no campo principalmente durante os estágios iniciais da cultura. Conhecer as principais doenças que afetam os plantios de eucalipto é fundamental para o sucesso dos sistemas agrossilvipastoris que empregam esta espécie. Assim este trabalho teve como objetivo relatar as principais doenças em plantios de eucalipto no Acre associados a sistemas silvipastoris em implantação. Foram avaliadas três áreas com plantios jovens de eucalipto com diferentes espécies. Nas áreas foram realizadas visitas mensais para detecção de doenças. Plantas com sintomas de doenças foram trazidas ao Laboratório de Fitopatologia da Embrapa Acre para diagnóstico. Em campo avaliou-se a incidência e severidade das doenças. Foram relatadas os seguintes patossistemas: Ralstonia solanacearum - Murcha Bacteriana; Xanthomonas axonopodis - Mancha Foliar Bacteriana do Eucalipto; Puccinia psidii - Ferrugem do Eucalipto; Coniella fragariae ? Mancha de Coniela; e Cylindrocladium spp. ? Mancha de Cylindrocladium.

Diversidade genética de Xanthomonas citri subsp. citri, caracterização molecular e patogênica de Xanthomonas fuscans subsp. aurantifolii e detecção de Xanthomonas alfalfae em citrumelo ‘Swingle’ (Citrus paradisi Macf. x Poncirus trifoliata L. Raf.) no Brasil

Pós-graduação em Microbiologia Agropecuária - FCAV

Caracterização molecular de proetínas envolvidas nos mecanismos de homeostase de cobre em Xanthomonas citri subsp. citri

Pós-graduação em Biotecnologia - IQ

Outbreak of angular leaf spot, caused by Xanthomonas fragariae, in a Queensland strawberry germplasm collection.

Strawberry (Fragaria (x) ananassa) plants exhibiting leaf lesions consistent with angular leaf spot (ALS, caused by Xanthomonas fragariae Kennedy and King 1962) were identified in the Queensland strawberry germplasm at Bundeberg in May 2010. Water suspensions of bacterial ooze tested positive using a previously described primer set. However, the slow growth rate of X. fragariae and the presence of a fast-growing, non-pathogenic, undescribed Xanthomonas species presented problems that were overcome by dilution plating and DNA sequence analysis. Sequencing of the gyrB locus of putative colonies of X. fragariae indicated 100% sequence similarity to other X. fragariae isolates. A new set of diagnostic primers for X. fragariae based on the gyrB locus is presented.

Tolerancia de diferentes variedades de repollo (Brassica oleracea L.) a la bacteriosis causada por Xanthomonas campestris pv. campestris P.

Con el objetivo determinar el grado de tolerancia de diferentes variedades de repollo a la bacteriosis (xanthomonas campestri pv. Campestri) y evaluar su adaptabilidad y rendimiento en la zona de la concepción , Masaya, se establecieron ensayos en invernadero y campo en el periodo comprendido entre el 17 de abril al 17 de noviembre de 1989. Se evaluaron 10 variedades de repollo bajo las condiciones de inoculación artificial en el invernadero de las cuales la variedad superette resulto la más susceptible a la bacteriosis; las variedades yasseng e izalco resultaron las más tolerantes. Otras variedades como King kole, Premium y potye resultaron menos susceptibles. A nivel de campo se evaluaron 5 variedades seleccionadas de acuerdo a su grado de tolerancia a bacteriosis y representatividad en el país de las cuales fueron superette, izalco resulto más tolerante a la bacteriosis mientras que la variedad superette mostro alta susceptibilidad seguido por King kole, Premium y copenhagen. Los rendimientos en las variedades susceptibles a la bacteriosis resultaron bajos comparados con izalco.

Efecto de tratamiento de semilla sobre la incidencia de tizón común (Xanthomonas campestris p.v. phaseoli) en frijol (Phaseolus vulgaris L.)

En las pruebas de calidad de semilla, ocho diferentes variedades de frijol común colectadas de una parcela experimental infectada por tizón común mostraron la presencia de Xanthomonas campestri pv. Phaseoli . Las variedades Revolución 799ª, Revolución 79 y Revolución 84 mostraron menos grado de infección bacteriana mientras las variedades ICA-PIJAO, Honduras -46, Revolución 81 y Revolución 85 mostraron alto grado de infección: El grado de infección bacteriana en las semillas afecto adversamente su capacidad germinativa: los tratamientos físicos como Agua caliente (50º C) por 10,15 y 20 minutos y tratamientos químicos como Agrimicia (100 y 200 ppm), Formalina 5% y Sulfato de cobre 200 ppm no mostraron ser efectivos para reducir el grado de infección significativamente: Los mismos tratamientos aplicados a la semilla infectada no resultaron efectivos para reducir el grado de infección significativamente: Los mismos tratamientos aplicados a la semilla infectada no resultaron efectivos para reducir la severidad de tizón común en el campo donde las condiciones climáticas eran favorables para l desarrollo de la enfermedad y se realizó control mecánico de malezas: La alta severidad de tizón común registrada durante el ciclo trajo como consecuencia rendimientos muy por debajo del rendimiento potencial: La obtención de sillas de los campos libres o con baja incidencia de tizón común es la única práctica que puede asegurar semillas libre de este patógeno y por lo tanto una buena cosecha.

Detecção e identificação molecular de Xanthomonas spp. causadoras da mancha bacteriana do tomateiro.

Neste comunicado são relatados os procedimentos para a identificação molecular das quatro espécies de Xanthomonas associadas à mancha bacteriana do tomateiro.

The Rpf/DSF system and the regulation of virulence in the plant pathogen Xanthomonas campestris

The full virulence of Xanthomonas campestris pv. campestris (Xcc) to plants depends upon cell-to-cell signalling mediated by the signal molecule DSF (for diffusible signal factor), that has been characterised as cis-11-methyl-2-dodecenoic acid. DSF-mediated signalling regulates motility, biofilm dynamics and the synthesis of particular virulence determinants. The synthesis and perception of the DSF signal molecule involves products of the rpf (regulation of pathogenicity factors) gene cluster. DSF synthesis is fully dependent on RpfF, which encodes a putative enoyl-CoA hydratase. A two-component system, comprising the complex sensor histidine kinase RpfC and the HD-GYP domain regulator RpfG, is implicated in DSF perception. The HD-GYP domain of RpfG is a phosphodiesterase working on cyclic di-GMP; DSF perception is thereby linked to the turnover of this intracellular second messenger. The full range of regulatory influences of the Rpf/DSF system and of cyclic di-GMP in Xcc has yet to be established. In order to further characterise the Rpf/DSF regulatory network in Xcc, a proteomic approach was used to compare protein expression in the wildtype and defined rpf mutants. This work shows that the Rpf/DSF system regulates a range of biological functions that are associated with virulence and biofilm formation but also reveals new functions mediated by DSF regulation. These functions include antibiotic resistance, detoxification and stress tolerance. Mutational analysis showed that several of these regulated protein functions contribute to virulence in Chinese radish. Interestingly, it was demonstrated that different patterns of protein expression are associated with mutations of rpfF, rpfC and rpfG. This suggests that RpfG and RpfC have broader roles in regulation other than perception and transduction of DSF. Taken together, this analysis indicates the broad and complex regulatory role of Rpf/DSF system and identifies a number of new functions under Rpf/DSF control, which were shown to play a role in virulence.

Presencia de Xanthomonas campestris pv. undulosa agente causal del rayado bacteriano en cultivos de trigo bajo riego

p.211-212

Stability of plasmid profile of highly virulent races of Xanthomonas campestris pv. malvacearum during storage and subculturing

Four races of Xanthomonas campestris pv. mal-vacearum (Xcm) viz. races 23, 27 and 32 (isolated from Gossypium hirsutum) and race 23b (from Gossypium barbadense) were studied. The plasmid profile of the natural isolates showed four plasmids in races 23 and 23b (ca. 60, 40, 23, 8.2 kb), five in race 27 (ca. 60, 40, 23, 8.2 and 3.7 kb) and six in race 32 (ca. 60, 40, 23, 8.2, 3.7 and 1.6 kb). Continuously sub-cultured laboratory isolates of the Xcm races resulted in the loss of all but two plasmids, ca. 60 and 40 kb in size. When the laboratory isolates were passed through cotton (Gossypium hirsutum), they regained certain plasmids so that four plasmids were found in race 23 and 23b (ca. 60, 40, 23 and 8.2 kb), five in race 27 (ca. 60, 40, 23, 8.2 and 3.7 kb) and six in race 32 (ca. 60, 40, 23, 8.2, 3.7 and 1.6 kb), which was more or less similar to the original isolates. The isolates recovered from cotton maintained their plasmid profile (except for minor changes in the miniplasmids) after storage for six months at -70degreesC in 50% glycerol. It is suggested that plasmid profiles among highly virulent races of Xcm are unstable during repeated sub-culturing at room temperature, resulting in rapid loss of some plasmids. However, when the cultures were sub-cultured and stored at -70degreesC the plasmid profile was fairly stable except for the miniplasmids (ca. 3.7 and 1.6 kb).

Stability in miniplasmids of Xanthomonas campestris pv. malvacearum during subculturing and storage - Abstract 7

Abstract 7

A mathematical model for the dynamics of Banana Xanthomonas Wilt with vertical transmission and inflorescence infection

A mathematical model for Banana Xanthomonas Wilt (BXW) spread by insect is presented. The model incorporates inflorescence infection and vertical transmission from the mother corm to attached suckers, but not tool-based transmission by humans. Expressions for the basic reproduction number R0 are obtained and it is verified that disease persists, at a unique endemic level, when R0 > 1. From sensitivity analysis, inflorescence infection rate and roguing rate were the parameters with most influence on disease persistence and equilibrium level. Vertical transmission parameters had less effect on persistence threshold values. Parameters were approximately estimated from field data. The model indicates that single stem removal is a feasible approach to eradication if spread is mainly via inflorescence infection. This requires continuous surveillance and debudding such that a 50% reduction in inflorescence infection and 2–3 weeks interval of surveillance would eventually lead to full recovery of banana plantations and hence improved production.