RESUMO
The pathogenicity of Xylella fastidiosa is associated with its ability to colonize the xylem of host plants. Expression of genes contributing to xylem colonization are suppressed, while those necessary for insect vector acquisition are increased with increasing concentrations of diffusible signal factor (DSF), whose production is dependent on RpfF. We previously demonstrated that transgenic citrus plants ectopically expressing rpfF from a citrus strain of X. fastidiosa subsp. pauca exhibited less susceptibility to Xanthomonas citri subsp. citri, another pathogen whose virulence is modulated by DSF accumulation. Here, we demonstrate that ectopic expression of rpfF in both transgenic tobacco and sweet orange also confers a reduction in disease severity incited by X. fastidiosa and reduces its colonization of those plants. Decreased disease severity in the transgenic plants was generally associated with increased expression of genes conferring adhesiveness to the pathogen and decreased expression of genes necessary for active motility, accounting for the reduced population sizes achieved in the plants, apparently by limiting pathogen dispersal through the plant. Plant-derived DSF signal molecules in a host plant can, therefore, be exploited to interfere with more than one pathogen whose virulence is controlled by DSF signaling.
Assuntos
Proteínas de Bactérias/metabolismo , Citrus/genética , Citrus/microbiologia , Nicotiana/genética , Nicotiana/microbiologia , Doenças das Plantas/microbiologia , Xylella/metabolismo , Regulação Bacteriana da Expressão Gênica , Plantas Geneticamente Modificadas , Transformação Genética , Xylella/genéticaRESUMO
In this study, kinetic parameters were determined for the biodegradation of BTX compounds in a fixed-bed reactor with immobilized biomass, fed with mono- and multicomponent systems. The parameter estimation was achieved through an algorithm using the finite volume method. Different kinetic models were evaluated. The Monod model proved to be suitable to predict the experimental data for the biodegradation individual BTX compound. In multicomponent systems, it was found that the presence of more than one compound tends to cause competitive inhibition. To identify the models that best fit the experimental data, a statistical analysis using the F test was applied. For the two- and three-component systems the presence of more than one compound tends to cause competitive inhibition. In this study, it was possible to predict kinetic parameters in mono- and multicomponent systems as well as different operation conditions for a fixed-bed reactor with immobilized biomass.
Assuntos
Benzeno/metabolismo , Biodegradação Ambiental , Biomassa , Tolueno/metabolismo , Xilenos/metabolismo , Cinética , Modelos TeóricosRESUMO
Biodesulfurization is an eco-friendly technology applied in the removal of sulfur from fossil fuels. This technology is based on the use of microorganisms as biocatalysts to convert the recalcitrant sulfur compounds into others easily treatable, as sulfides. Despite it has been studied during the last decades, there are some unsolved questions, as per example the kinetic model which appropriately describes the biodesulfurization globally. In this work, different kinetic models were tested to a batch desulfurization process using dibenzothiophene (DBT) as a model compound, n-dodecane as organic solvent, and Rhodococcus erythropolis ATCC 4277 as biocatalyst. The models were solved by ODE45 function in the MATLAB. Monod model was capable to describe the biodesulfurization process predicting all experimental data with a very good fitting. The coefficients of determination achieved to organic phase concentrations of 20, 80, and 100 % (v/v) were 0.988, 0.995, and 0.990, respectively. R. erythropolis ATCC 4277 presented a good affinity with the substrate (DBT) since the coefficients of saturation obtained to reaction medium containing 20, 80, and 100 % (v/v) were 0.034, 0.07, and 0.116, respectively. This kinetic evaluation provides an improvement in the development of biodesulfurization technology because it showed that a simple model is capable to describe the throughout process.
Assuntos
Combustíveis Fósseis/microbiologia , Modelos Biológicos , Rhodococcus/metabolismo , Enxofre/metabolismo , Cinética , Solventes/química , Tiofenos/metabolismoRESUMO
Some of the noxious atmospheric pollutants such as nitrogen and sulfur dioxides come from the fossil fuel combustion. Biodesulfurization and biodenitrogenation are processes which remove those pollutants through the action of microorganisms. The ability of sulfur and nitrogen removal by the strain Rhodococcus erythropolis ATCC 4277 was tested in a biphasic system containing different heavy gas oil concentrations in a batch reactor. Heavy gas oil is an important fraction of petroleum, because after passing through, the vacuum distillation is incorporated into diesel oil. This strain was able to remove about 40% of the nitrogen and sulfur present in the gas heavy oil. Additionally, no growth inhibition occurred even when in the presence of pure heavy gas oil. Results present in this work are considered relevant for the development of biocatalytic processes for nitrogen and sulfur removal toward building feasible industrial applications.
Assuntos
Gases/metabolismo , Dióxido de Nitrogênio/metabolismo , Petróleo , Rhodococcus/crescimento & desenvolvimento , Dióxido de Enxofre/metabolismoRESUMO
Cellulase is one of the enzymes most commonly used in the textile industry for the biopolishing process. The appropriate choice of pretreatment is a possible route to promoting enzymatic attack in situations in which this is not favored due to the effects of packing. In order to evaluate the influence of pretreatment the yarn was maintained in water for 24h before biopolishing to promote greater spacing between the chains. In the tensile testing the pretreated Combed 13/1 yarn showed a greater percentage reduction in the maximum breaking force following biopolishing, evidencing a stronger enzymatic attack. Also, the Combed 13/1 and OE 14/1 yarns without pretreatment had an approximately 22% reduction in the shrinkage and after pretreatment the Carded 13/1 yarn had the best shrinkage reduction values (18%). These data demonstrate that the introduction of the pretreatment promotes a change in the access of the enzyme to the fiber.
Assuntos
Celulase/química , Celulose/química , Gossypium/química , Óleos Industriais , Resistência à Tração , Fibra de Algodão/métodos , Ensaios Enzimáticos , Teste de Materiais/métodos , Microfibrilas/química , Estresse Mecânico , Água/químicaRESUMO
The decline in stocks of commercial fish species has been documented in several regions of the world. This decline is due partially to the effect of evolutionary pressure caused by the management of fishing activity, which reduces the size of fish after a few generations. In this paper, the population dynamics of the Pintado Pseudoplatystoma corruscans, one of the main commercial species of freshwater fish in Brazil, were simulated considering different scenarios of fishing mortality and different minimum and maximum lengths of capture. The results show that selective fishing based on the different proposed selectivity curves can result in an evolution-mediated increase in the growth rate of the fish, the biomass and the catch. This suggests that appropriate changes in Brazilian legislation can contribute to the sustainability of fisheries and to conservation of the fish stocks exploited by man.
Assuntos
Peixes-Gato , Conservação dos Recursos Naturais/métodos , Animais , Evolução Biológica , Biomassa , Brasil , Peixes-Gato/genética , Simulação por Computador , Conservação dos Recursos Naturais/estatística & dados numéricos , Pesqueiros , Humanos , Modelos Logísticos , Dinâmica Populacional/estatística & dados numéricosRESUMO
In this study, the cytotoxicity, genotoxicity and early ROS generation of 2,2-dimethyl-(3H)-3-(N-3'-nitrophenylamino)naphtho[1,2-b]furan-4,5-dione (QPhNO(2)) were investigated and compared with those of its precursor, nor-beta-lapachone (nor-beta), with the main goal of proposing a mechanism of antitumor action. The results were correlated with those obtained from electrochemical experiments held in protic (acetate buffer pH 4.5) and aprotic (DMF/TBABF(4)) media in the presence and absence of oxygen and with those from dsDNA biosensors and ssDNA in solution, which provided evidence of a positive interaction with DNA in the case of QPhNO(2). QPhNO(2) caused DNA fragmentation and mitochondrial depolarization and induced apoptosis/necrosis in HL-60 cells. Pre-treatment with N-acetyl-l-cysteine partially abolished the observed effects related to the QPhNO(2) treatment, including those involving apoptosis induction, indicating a partially redox-dependent mechanism. These findings point to the potential use of the combination of pharmacology and electrochemistry in medicinal chemistry.
Assuntos
Antineoplásicos/farmacologia , Benzofuranos/farmacologia , Naftoquinonas/farmacologia , Apoptose/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Ensaio Cometa , Dano ao DNA , Células HL-60 , Humanos , Oxirredução , Espécies Reativas de Oxigênio/metabolismoRESUMO
Radyosinovectomy (RSV) is a radiotherapeutic modality where a beta-emitting radionuclide is administered locally by intra-articular injection on the form of a colloid or radiolabeled particulate. RSV is a well-accepted therapeutic procedure in inflammatory joint diseases and has been successfully employed for more than 50 years as a viable alternative to surgical and chemical synovectomy. The aim of this work is to compare the in vivo stability of hydroxyapatite labelled with (177)Lu, (90)Y and (153)Sm. All radionuclides were labelled with high yield and were retained in the joint for 7 days, showing stability and usefulness as tools in the RSV treatment. A similar retention of the products in the muscle was observed when the particles were administrated in the muscle. However, the pure form of the radionuclides were rapidly cleared from the blood and accumulated in the liver when injected i.v.. Although (153)Sm-HA is already available for nuclear medicine procedures and clinical studies with (90)Y-HA have been developed, (177)Lu-labeled RSV agents will be economically more viable and has not been studied yet. Its favorable characteristics contribute to follow, to predict and asses the success of RSV by bone scintigraphy studies.
Assuntos
Durapatita/química , Injeções Intra-Articulares/métodos , Animais , Partículas beta , Coloides/química , Raios gama , Membro Posterior/diagnóstico por imagem , Inflamação , Lutécio/química , Tamanho da Partícula , Radioisótopos/química , Cintilografia , Ratos , Ratos Wistar , Samário/química , Distribuição Tecidual , Imagem Corporal Total , Radioisótopos de Ítrio/químicaRESUMO
Xylella fastidiosa is a xylem-dwelling, insect-transmitted, gamma-proteobacterium that causes diseases in many plants, including grapevine, citrus, periwinkle, almond, oleander, and coffee. X. fastidiosa has an unusually broad host range, has an extensive geographical distribution throughout the American continent, and induces diverse disease phenotypes. Previous molecular analyses indicated three distinct groups of X. fastidiosa isolates that were expected to be genetically divergent. Here we report the genome sequence of X. fastidiosa (Temecula strain), isolated from a naturally infected grapevine with Pierce's disease (PD) in a wine-grape-growing region of California. Comparative analyses with a previously sequenced X. fastidiosa strain responsible for citrus variegated chlorosis (CVC) revealed that 98% of the PD X. fastidiosa Temecula genes are shared with the CVC X. fastidiosa strain 9a5c genes. Furthermore, the average amino acid identity of the open reading frames in the strains is 95.7%. Genomic differences are limited to phage-associated chromosomal rearrangements and deletions that also account for the strain-specific genes present in each genome. Genomic islands, one in each genome, were identified, and their presence in other X. fastidiosa strains was analyzed. We conclude that these two organisms have identical metabolic functions and are likely to use a common set of genes in plant colonization and pathogenesis, permitting convergence of functional genomic strategies.
Assuntos
Citrus/microbiologia , Gammaproteobacteria/genética , Genoma Bacteriano , Doenças das Plantas/microbiologia , Sequência de Bases , Dados de Sequência MolecularRESUMO
Eight cases of cutaneous leishmaniasis are recorded among soldiers of the Brazilian Forest Infantry stationed in Belém, State of Pará, north of Brazil. The infections, all acquired during manoeuvres in nearby degraded primary forest, are attributed to a new member of the subgenus Viannia, Leishmania (V.) lindenbergi n. sp. A further infection by this parasite was encountered in a woman, who lived very close to the same piece of forest. The new parasite has been characterised and differentiated from other known species of the subgenus Viannia following the combined use of enzyme electrophoresis and monoclonal antibodies techniques. The eco-epidemiology of L. (V.) lindenbergi is discussed: by far the most abundant anthropophilic sandfly in the type locality was identified as Lutzomyia (Nyssomyia) antunesi (Coutinho), and this remains high on the list of possible vectors.
Assuntos
Surtos de Doenças , Leishmania/isolamento & purificação , Leishmaniose Cutânea/epidemiologia , Militares , Animais , Anticorpos Monoclonais/imunologia , Anticorpos Antiprotozoários/imunologia , Antígenos de Protozoários/imunologia , Antiprotozoários/uso terapêutico , Brasil/epidemiologia , Feminino , Humanos , Insetos Vetores/parasitologia , Isoenzimas/análise , Leishmania/classificação , Leishmania/crescimento & desenvolvimento , Leishmania/imunologia , Leishmania/ultraestrutura , Leishmaniose Cutânea/tratamento farmacológico , Leishmaniose Cutânea/parasitologia , Masculino , Mefloquina/uso terapêutico , Meglumina/uso terapêutico , Antimoniato de Meglumina , Compostos Organometálicos/uso terapêutico , Proteínas de Protozoários/análise , Psychodidae/parasitologia , ÁrvoresRESUMO
Short sequence repeats (SSRs) with a potential variable number of tandem repeat (VNTR) loci were identified in the genome of the citrus pathogen Xylella fastidiosa and used for typing studies. Although mono- and dinucleotide repeats were absent, we found several intermediate-length 7-, 8-, and 9-nucleotide repeats, which we examined for allelic polymorphisms using PCR. Five genuine VNTR loci were highly polymorphic within a set of 27 X. fastidiosa strains from different hosts. The highest average Nei's measure of genetic diversity (H) estimated for VNTR loci was 0.51, compared to 0.17 derived from randomly amplified polymorphic DNA (RAPD) analysis. For citrus X. fastidiosa strains, some specific VNTR loci had a H value of 0.83, while the maximum value given by specific RAPD loci was 0.12. Our approach using VNTR markers provides a high-resolution tool for epidemiological, genetic, and ecological analysis of citrus-specific X. fastidiosa strains.
Assuntos
Citrus/microbiologia , Gammaproteobacteria/classificação , Gammaproteobacteria/genética , Repetições Minissatélites/genética , Doenças das Plantas/microbiologia , Técnicas de Tipagem Bacteriana , DNA Bacteriano/análise , DNA Bacteriano/genética , Reação em Cadeia da Polimerase , Técnica de Amplificação ao Acaso de DNA PolimórficoRESUMO
Phylogenetic analysis of all 31 described mitochondrial (cytochrome b) haplotypes of Lutzomyia whitmani demonstrated that new material from the State of Rondônia, in southwest Amazônia, forms a clade within a lineage found only in the rain-forest regions of Brazil. This rain-forest lineage also contains two other clades of haplotypes, one from eastern Amazônia and one from the Atlantic forest zone of northeast Brazil (including the type locality of the species in Ilhéus, State of Bahia). These findings do not favour recognizing two allopatric cryptic species of L. whitmani, one associated with the silvatic transmission of Leishmania shawi in southeast Amazônia and the other with the peridomestic transmission of Le. braziliensis in northeast Brazil. Instead, they suggest that there is (or has been in the recent past) a continuum of inter-breeding populations of L. whitmani in the rain-forest regions of Brazil.
Assuntos
DNA Mitocondrial/genética , Psychodidae/genética , Animais , Brasil , Grupo dos Citocromos b/análise , Feminino , Humanos , Leishmaniose/transmissão , Masculino , Filogenia , Reação em Cadeia da Polimerase , Psychodidae/classificação , Análise de Sequência de DNA , Especificidade da Espécie , ÁrvoresRESUMO
Cysticercosis is the most ordinary parasitary disease involving the nervous system. The involvement of the spine is rare, ranging from 0.7% to 5.8%, and the intramedullary incidence is rather uncommon. We report the case of a 52-year-old female patient with intramedullary cysticercosis at the C4-C5 level, treated at the Neurology and Neurosurgery Service of Santa Casa de Belo Horizonte. The patient was operated with the complete exeresis of the lesion and had a good outcome. Forty-five cases of intramedullary cysticercosis were found in the literature review. We conclude that although it is a rare pathology, intramedullary cysticercosis should be included in the differential diagnosis of intramedullary lesions, mainly in cases of patients with previous diagnosis for neurocysticercosis and also of those who live in endemic areas.
Assuntos
Cisticercose/patologia , Medula Espinal/patologia , Cisticercose/cirurgia , Feminino , Humanos , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , Radiografia , Crânio/diagnóstico por imagem , Medula Espinal/cirurgiaAssuntos
Filogenia , Psychodidae/genética , Animais , Brasil , Demografia , Insetos Vetores , Topografia MédicaRESUMO
Six species of Leishmania are at present known to cause cutaneous and/or mucocutaneous leishmaniasis in Brazil, and they are all to be found in the Amazon region of this country. The eco-epidemiology of each is discussed, with the observation that the Amazonian leishmaniases are all zoonoses, with their source in silvatic mammals and phlebotomine sandfly vectors. With man's destruction of the natural forest in southern Brazil, some sandfly species have survived by adapting to a peridomestic or domiciliary habitat in rural areas. Some domestic animals, such as dogs and equines are seemingly now involved in the epidemiology of the disease. No such process has yet been reported in the Amazon region, but may well take place with the continuing devastation of its forest.
Assuntos
Leishmaniose Cutânea/epidemiologia , Leishmaniose Mucocutânea/epidemiologia , Animais , Brasil/epidemiologia , Ecologia , Humanos , Leishmania/fisiologia , Leishmania braziliensis/fisiologia , Leishmania guyanensis/fisiologia , Leishmaniose Cutânea/diagnóstico , Leishmaniose Cutânea/parasitologia , Leishmaniose Mucocutânea/diagnóstico , Leishmaniose Mucocutânea/parasitologiaRESUMO
The clinical and epidemiological features of 62 cases of cutaneous leishmaniasis due to Leishmania (Leishmania) amazonensis, from Pará State, Amazonian Brazil, are discussed. The parasite, isolated in hamster skin and/or blood-agar culture medium, was in each case identified by both biological characteristics and a monoclonal antibody specific for promastigotes of L. (L.) amazonensis. Of the 62 patients, 46 (74.2%) presented with a single cutaneous lesion, and on no occasion was evidence found indicating metastatic spread to either the naso-pharyngeal mucosae or the viscera. Recent claims that this parasite may be responsible for both mucocutaneous leishmaniasis and typical visceral leishmaniasis are discussed. Meglumine antimoniate (Glucantime) proved highly efficient in the treatment of all patients. Of the 62 patients examined by the Montenegro skin test, only 32 (51.6%) gave a positive reaction. The significance of this finding is considered and the hypothesis made that the parasite itself may induce an immunoinhibition. Field studies amply confirmed the role of Lutzomyia flaviscutellata as the major sandfly vector of L. (L.) amazonensis in Amazonia.
Assuntos
Leishmaniose Cutânea/diagnóstico , Leishmaniose Cutânea/parasitologia , Adolescente , Adulto , Animais , Antiprotozoários/uso terapêutico , Brasil , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Leishmania mexicana , Leishmaniose Cutânea/tratamento farmacológico , Masculino , Meglumina/uso terapêutico , Antimoniato de Meglumina , Compostos Organometálicos/uso terapêutico , Testes CutâneosRESUMO
Leishmania (Viannia) shawi sp. n., is described from the monkeys Cebus apella and Chiropotes satanus, the sloths Choloepus didactylus and Bradypus tridactylus, the procyonid Nasua nasua, and the phlebotomine sandfly Lutzomyia whitmani, all from primary forest in the State of Pará, north Brazil. L. (V.) shawi is variably distinguished from all other known species within the subgenus Viannia by a combination of biological, biochemical and serological characters, as revealed by studies on morphology, isoenzyme profiles, kDNA buoyant densities and monoclonal antibodies.
Assuntos
Haplorrinos/parasitologia , Leishmania/classificação , Psychodidae/parasitologia , Bichos-Preguiça/parasitologia , Xenarthra/parasitologia , Animais , Brasil , Leishmania/anatomia & histologia , Leishmania/isolamento & purificaçãoRESUMO
The clinical characteristics of acute and chronic Chagas' disease in central Brazil are described (29 acute cases and 111 chronic cases). The geographical distribution of Trypanosoma cruzi zymodemes in this region was mapped. Zymodeme (Z) 1 was identified in 12 acute cases, Z2 in 13 and repeated xenodiagnosis gave the same zymodeme identification. The clinical pictures of the Z1 and Z2 acute phases were similar. Resistance to benznidazole treatment occurred after either Z1 or Z2 acute infections. Only 14 positive xenodiagnosis were obtained from the 111 chronic phase patients examined. For 12 of these 14 patients the zymodeme was identified. All 12 carried Z2, 10 of whom had mega involvement. There were several possible explanations for the failure to detect T. cruzi Z1 in chronic Chagas' disease with mega syndromes: suggestions were made for follow-up investigations.