RESUMO
Although challenging, developing evidence-based approaches to an early and accurate diagnosis of systemic lupus erythematosus is a key approach to preventing disease and lupus-associated morbidity and mortality. Advances in our understanding of preclinical and incomplete lupus erythematosus have enabled the identification of risk factors that may predict disease and the development of potential strategies aimed at primary prevention. Emerging data support the notion that there is a temporal disease progression from initial asymptomatic autoimmunity (preclinical lupus) through early clinical features of the disease (incomplete lupus erythematosus) to finally becoming fully classifiable systemic lupus erythematosus (complete lupus erythematosus). Here, we review the demographic, clinical, biomarker as well as genetic and environmental features that are reported to increase the risk of disease progression. Based on these risk factors, we propose a clinical care pathway for patients with early disease. We envisage that such a pathway, through early identification of disease, may improve patient outcomes, while reducing health care costs.
Assuntos
Anticorpos Antinucleares/sangue , Progressão da Doença , Lúpus Eritematoso Sistêmico/diagnóstico , Lúpus Eritematoso Sistêmico/prevenção & controle , Biomarcadores/sangue , Procedimentos Clínicos , Humanos , Lúpus Eritematoso Sistêmico/economia , Morbidade , Prevenção Primária/métodos , Fatores de RiscoRESUMO
Enhancing immunological responses to vaccination is an important goal in many herd health management systems. OmniGen-AF®(OG) is an immunomodulatory feed additive that has been shown to enhance innate immune function in ruminants and its effects on adaptive immunity require additional study. The objective of this study was to evaluate post-vaccine antibody titers and circulating cellular memory development in heifers fed OG and administered a commercially available modified-live bovine respiratory disease (BRD) vaccine. Twenty-four Holstein heifers were assigned to one of two diets for 170â¯days: Control TMR (CON; nâ¯=â¯11), or TMR plus OG (TRT; 9â¯g/100â¯kg BW/day; nâ¯=â¯13). Samples for hematology, serology, and cellular assays were collected on D-110, 0, 21, 42, and 60 of the trial. Heifers were administered two priming doses of a modified-live BRD vaccine, with a third dose given on D0. There were no significant differences in total WBC and absolute number or the percentage of circulating lymphocytes, monocytes, neutrophils, RBC, or platelets on D-110 through D21. On D42 and D60, CON had significantly higher numbers of lymphocytes. On D0, mean serum neutralizing (SN) titer to BHV-1 was significantly higher for CON compared to TRT. SN titers were not significantly different between CON and TRT at any other time point for BHV-1, BVDV type 1, or BVDV type 2. TRT mounted a significantly stronger recall proliferative response to 0.5 multiplicity of infection (MOI) of BHV-1, BVDV type 1 and BVDV type 2 on D42 and D60; 0.25 MOI of BVDV type 1 on D21 and D42; and 0.25 MOI BVDV type 2 on D42 compared to CON. IL-4 production induced by 0.5 and 1.0 MOI BHV-1 (D42 and D60); 0.25 MOI of BVDV type 1 (D21); and 0.25 and 0.5 MOI of BVDV type 2 (D60) were significantly higher for TRT than CON. IL-17 production induced by 0.25 MOI of BVDV type 1 was significantly higher on D60 for TRT compared to CON. IFN-gamma and IL-10 were not significantly different between treatments. These data indicate feeding OG has a beneficial effect on responses to vaccine antigens in Holstein dairy heifers.
Assuntos
Antígenos Virais/imunologia , Vírus da Diarreia Viral Bovina Tipo 1/imunologia , Vírus da Diarreia Viral Bovina Tipo 2/imunologia , Herpesvirus Bovino 1/imunologia , Fatores Imunológicos/imunologia , Vacinas Virais/imunologia , Ração Animal/análise , Animais , Complexo Respiratório Bovino/imunologia , Bovinos , Dieta/veterinária , Suplementos Nutricionais/análise , Feminino , Fatores Imunológicos/administração & dosagemRESUMO
Our objective was to evaluate the effect of an injectable trace mineral (ITM) supplement containing zinc, manganese, selenium, and copper on the humoral and cell mediated immune (CMI) responses to vaccine antigens in dairy calves receiving a modified-live viral (MLV) vaccine containing BVDV, BHV1, PI3V and BRSV. A total of 30 dairy calves (3.5 months of age) were administered a priming dose of the MLV vaccine containing BHV1, BVDV1 & 2, BRSV, PI3V, and an attenuated-live Mannheimia-Pasteurella bacterin subcutaneously (SQ). Calves were randomly assigned to 1 of 2 groups: (1) administration of ITM SQ (ITM, n=15) or (2) injection of sterile saline SQ (Control; n=15). Three weeks later, calves received a booster of the same vaccine combination SQ, and a second administration of ITM, or sterile saline, according to the treatment group. Blood samples were collected on days 0, 7, 14, 21, 28, 42, 56, and 90 post-vaccination for determination of antibody titer, viral recall antigen-induced IFN-γ production, and viral antigen-induced proliferation by peripheral blood mononuclear cells (PBMC). Administration of ITM concurrently with MLV vaccination resulted in higher antibody titers to BVDV1 on day 28 after priming vaccination compared to the control group (P=0.03). Calves treated with ITM showed an earlier enhancement in PBMC proliferation to BVDV1 following vaccination compared to the control group. Proliferation of PBMC after BVDV stimulation tended to be higher on day 14 after priming vaccination in calves treated with ITM than in the control group (P=0.08). Calves that received ITM showed higher PBMC proliferation to BRSV stimulation on day 7 after priming vaccination compared to the control group (P=0.01). Moreover, calves in the ITM group also had an enhanced production IFN-γ by PBMC after stimulation with BRSV on day 21 after priming vaccination compared to day 0 (P<0.01). In conclusion, administration of ITM concurrently with MLV vaccination in dairy calves resulted in increased antibody titer to BVDV1, and greater PBMC proliferation to BVDV1 and BRSV recall stimulation compared to the control group, suggesting that ITM might represent a promising tool to enhance the humoral and CMI responses to MLV vaccines in cattle.
Assuntos
Doenças dos Bovinos/imunologia , Doenças dos Bovinos/prevenção & controle , Vírus da Diarreia Viral Bovina/imunologia , Herpesvirus Bovino 1/imunologia , Vírus Sincicial Respiratório Bovino/imunologia , Oligoelementos/administração & dosagem , Vacinas Virais/administração & dosagem , Animais , Anticorpos Neutralizantes/sangue , Anticorpos Antivirais/sangue , Doença das Mucosas por Vírus da Diarreia Viral Bovina/imunologia , Doença das Mucosas por Vírus da Diarreia Viral Bovina/prevenção & controle , Bovinos , Infecções por Herpesviridae/imunologia , Infecções por Herpesviridae/prevenção & controle , Infecções por Herpesviridae/veterinária , Imunidade Celular/efeitos dos fármacos , Imunidade Humoral/efeitos dos fármacos , Masculino , Infecções por Vírus Respiratório Sincicial/imunologia , Infecções por Vírus Respiratório Sincicial/prevenção & controle , Infecções por Vírus Respiratório Sincicial/veterinária , Vacinas Atenuadas/administração & dosagemRESUMO
Xanthomonas campestris pv. campestris (Xcc) is a vascular pathogen of cruciferous plants that normally gains entry to plants via hydathodes. In order to study the basis of the preference for this protal of entry we have developed an Arabidopsis thaliana model with attached or detached leaves partially immersed in a bacterial suspension. Entry of bacteria into leaves, assessed by resistance to surface sterilization, could be detected after 1 h. Dissection of leaves and histochemical staining for beta-glucuronidase produced by the bacteria indicated that they were located in hydathodes. In contrast, similar experiments with the leaf-spotting pathogen X. campestris pv. armoraciae gave patterns of localized staining dispersed over the leaf area, indicative of entry through stomata. A survey of 41 A. thaliana accessions showed that they fell into three classes distinguishable by total numbers of Xcc that entered under standard conditions and by preference for hydathode colonization. Previously isolated Xcc mutants affected in pathogenicity were tested for hydathode colonization: an hrp mutant behaved indistinguishably from the wild type, and rpf regulatory mutants gave 10-fold reduced colonization, whereas with rfaX mutants with altered lipopolysaccharide, few if any viable bacteria were recoverable from hydathodes. This fact, together with the rapid induction of superoxide dismutase in the bacteria located in hydathodes, suggests that an early defense reaction is mounted in the hydathode.
Assuntos
Arabidopsis/microbiologia , Doenças das Plantas/microbiologia , Folhas de Planta/microbiologia , Xanthomonas campestris/patogenicidade , Mutação , Superóxido Dismutase/metabolismo , Xanthomonas campestris/enzimologia , Xanthomonas campestris/genéticaRESUMO
All Xanthomonas campestris pathovars tested contain DNA which hybridizes to the large hrp gene cluster of Pseudomonas solanacearum (C.A. Boucher, F. Van Gijsegem, P.A. Barberis, M. Arlat, and C. Zischek, J. Bacteriol. 169:5626-5632, 1987). Clones carrying these sequences were isolated from genomic libraries of X. campestris pvs. campestris and vitians. Mutagenesis of the corresponding genomic regions of both pathovars gave strains defective in both pathogenicity and hypersensitive response induction. X. c. pv. campestris contained a hrp gene cluster covering about 25 kb, which was homologous and colinear over a continuous 19-kb DNA region with the P. solanacearum hrp cluster. Cross-complementation showed that X. c. pv. vitians and X. c. pv. campestris hrp sequences are functionally interchangeable, but the source of the hrp genes did not determine the compatibility-incompatibility of the host-pathogen interaction. One X. c. pv. campestris Hrp- mutant was "complemented" by specific subclones of the P. solanacearum hrp cluster, suggesting the existence of some functional homology between the clusters of the two species. Expression of hrp genes (studied by lacZ fusions) was repressed in rich medium, and in minimal medium the level of expression depended on the carbon source supplied to the cells. Transcription of hrp genes was not regulated by genes that control the synthesis of extracellular enzymes, which are required for pathogenicity. In addition X. campestris Hrp- mutants produced wild-type levels of these extracellular enzyme activities. These results suggest the existence of two independent sets of pathogenicity genes that are regulated differently.
Assuntos
Família Multigênica , Pseudomonas/genética , Xanthomonas campestris/genética , Mapeamento Cromossômico , Clonagem Molecular , Elementos de DNA Transponíveis , DNA Bacteriano , Genes Bacterianos , Teste de Complementação Genética , Mutagênese , Pseudomonas/patogenicidade , Xanthomonas campestris/patogenicidadeRESUMO
Infiltration of leaves of Arabidopsis thaliana accession Columbia with Xanthomonas campestris pathovar campestris leads to bacterial growth and disease symptoms reminiscent of those incited in Brassica plants inoculated under the same conditions. A search among A. thaliana accessions for variation in the reaction phenotype to strains of X. campestris pathovars campestris, aberrans, and raphani showed that there were no clear differential responses between plant accessions to the individual bacterial strains tested. X. c. pv. raphani strain 1067 was avirulent to all A. thaliana accessions tested. A gene was cloned from X. c. pv. raphani 1067 which, when transferred into the virulent X. c. pv. campestris strain 8004, strongly reduced symptom development and bacterial growth in A. thaliana Columbia plants but did not affect virulence to Brassica plants. The gene (denoted avrXca) interacted with all A. thaliana accessions tested except one, Kas-1, which developed disease symptoms and supported growth of the transconjugant to levels similar to those with X. c. pv. campestris 8004 alone. Sequence analysis of avrXca revealed a probable open reading frame encoding a protein of 66,566 Da that has no homology with other known sequences. A sequence motif conserved among hrp genes was identified in the 5' noncoding region of avrXca, and features characteristic of a signal peptide were found in the N-terminal portion of the presumed AvrXca protein. DNA from different phytopathogenic bacteria contained sequences hybridizing with avrXca in related X. campestris pathovars but not in Erwinia or Pseudomonas strains.
Assuntos
Arabidopsis/microbiologia , Genes Bacterianos/genética , Doenças das Plantas/genética , Xanthomonas campestris/genética , Xanthomonas campestris/patogenicidade , Sequência de Aminoácidos , Sequência de Bases , Clonagem Molecular , Variação Genética , Dados de Sequência Molecular , Mutagênese Insercional , Mapeamento por Restrição , Análise de Sequência de DNA , Especificidade da Espécie , Virulência/genéticaRESUMO
One hundred thirty incident cases of head and neck cancer in Boston between September 1, 1985, and March 31, 1988, provided interview or medical record review data on the use of health services in the 24 months preceding the diagnosis of cancer. One hundred twenty-four subjects were able to recall whether and how often they visited health care sites in this period, reporting a median number of 10.5 visits; 94% recalled at least one visit. Eighty-nine medical record reviews indicated a median of seven visits. For the most part, these visits were to providers whom subjects considered their regular source of care--sources that provided care in a broad range of locations. These data support a strategy of integrating screening for head and neck cancers into existing health care services.
Assuntos
Carcinoma de Células Escamosas/diagnóstico , Neoplasias de Cabeça e Pescoço/diagnóstico , Aceitação pelo Paciente de Cuidados de Saúde/estatística & dados numéricos , Adulto , Boston , Serviços de Saúde Bucal/estatística & dados numéricos , Serviços de Saúde/estatística & dados numéricos , Humanos , Massachusetts , Prontuários Médicos , Estudos ProspectivosRESUMO
The dimension of time perspective for extension of personal future was examined as it may be affected by response format and coding procedures. A total of 75 undergraduate students responded to a questionnaire containing one of three formats for reporting anticipated future life-events, varying in the structure imposed on responding. Temporal estimates of life-event occurrence were coded using two procedures, each of which permitted a near and a far value. Analyses suggest that the greatest degree of caution should occur in considering the representativeness of far estimates of extension provided under an open-event format. While coding procedures each produced a significant near/far difference, cross-procedure comparisons were not as impressive, despite also being significant. Questions can therefore be raised regarding techniques for obtaining time perspective data and preparing them for analysis.
Assuntos
Percepção do Tempo , Adulto , Feminino , Humanos , Acontecimentos que Mudam a Vida , Masculino , PesquisaRESUMO
The aim of this study was to describe the clinical course of patients with lupus nephritis (LN) who attain a sustained remission (SR) and identify predictors of SR. A retrospective study of patients with biopsy-proven LN were followed for up to 10 years. SR was defined as normal renal function, urine protein <0.5g/day, and an inactive urine sediment without significant immunosuppressive maintenance therapy for no less than three years. Control patients had LN but did not fulfill the criteria for SR. Data was collected at diagnosis of LN (T0), at onset of remission (T1), and at final follow-up (T2). A total of 35 patients were identified, 16 with a SR of LN and 19 controls, with a mean +/- SD follow-up of 126.4 +/- 8.5 months. Remission of LN was achieved following 37.7 +/- 6.8 months of therapy. At diagnosis (T0) the WHO classification of nephritis, activity and chronicity scores of renal biopsies were comparable in the two groups. At final follow-up (T2), the mean estimated creatinine clearance for the SR group was significantly higher than in controls (P = 0.009) and disease activity (SLEDAI scores) was lower (P = 0.002). Cumulative damage (SDI scores) in the SR group did not increase after patients entered remission (P = 0.250), whereas the mean SDI score in the control group increased significantly (P = 0.014) even when renal variables were excluded (P = 0.016). Multivariate analysis revealed that female gender (P = 0.023), older age (P = 0.034), higher nonrenal SLEDAI scores (P = 0.016) at the time of diagnosis of LN and absence of azathioprine (P = 0.010) were predictive of SR. It was concluded that remission of LN occurs in a substantial proportion of systemic lupus erythematosus (SLE) patients and may be sustained without maintenance immunosuppressive therapy. It is associated with a significantly slower accrual of both renal and non-renal damage over the ensuing seven years.
Assuntos
Corticosteroides/uso terapêutico , Imunossupressores/uso terapêutico , Nefrite Lúpica/tratamento farmacológico , Corticosteroides/administração & dosagem , Adulto , Antirreumáticos/uso terapêutico , Azatioprina/uso terapêutico , Creatinina/metabolismo , Ciclofosfamida/administração & dosagem , Ciclofosfamida/uso terapêutico , Progressão da Doença , Feminino , Humanos , Hidroxicloroquina/uso terapêutico , Imunossupressores/administração & dosagem , Modelos Logísticos , Nefrite Lúpica/patologia , Masculino , Análise Multivariada , Indução de Remissão , Estudos Retrospectivos , Resultado do TratamentoRESUMO
The human polyomavirus BK virus (BKV) remains latent in the urinary tract and may be reactivated in immunocompromised states. BKV is noted to be the etiologic agent of polyomavirus-associated nephropathy (PVAN), which is a significant cause of allograft failure in renal transplant patients. Renal dysfunction following non-renal solid organ transplantation is common and is typically attributed to drug toxicity or patient comorbidities. In this article we describe a case of PVAN in the native kidneys of a heart transplant recipient and review the literature. Although this is only the fourth case reported, BKV nephropathy should be considered in the differential diagnosis of new renal failure following non-kidney solid organ transplantation, as early diagnosis of PVAN is necessary to prevent irreversible renal damage.
Assuntos
Vírus BK/crescimento & desenvolvimento , Transplante de Coração/imunologia , Nefropatias/virologia , Adulto , Humanos , Nefropatias/imunologia , MasculinoRESUMO
A frequently reported finding in age-related sensory impairment is that olfaction shows consistent and uniform decline with age. In most studies, discerning whether loss in olfaction is due to aging per se or to factors extrinsic to the aging process (e.g., smoking, chemical exposure, head injury) is difficult. Moreover, studies of olfaction have generally relied on data collected from samples drawn primarily from Western societies. As such, little is known regarding differences in olfaction involving non-Western cultures. Using international data from the 1986 National Geographic Smell Survey, responses of 19,219 American respondents and 3,204 respondents from Africa were analyzed. All respondents were screened for factors negatively affecting olfaction. Measures of olfactory acuity included odor detection, identification, intensity, and quality. The odor of interest was androstenone, a scent produced by bacteria on the human body and appearing in sweat. The results indicate that some measures of olfactory acuity tend to decline across age groups, but that this decline is less marked than reported in previous studies. The most important finding is that loss of olfaction is not consistent or uniform between geographic regions of America or Africa, between male vs. female respondents, or among the four measures of olfactory acuity. African respondents (both men and women) had significantly higher percentages of detection than did American respondents, women generally reported higher levels of olfactory functioning than did men, and some measures of olfaction were stable across age groups, or were higher among older respondents (e.g., odor identification).
Assuntos
Envelhecimento/psicologia , Comparação Transcultural , Etnicidade/psicologia , Olfato , Adolescente , Adulto , África , Idoso , Idoso de 80 Anos ou mais , Canadá , Criança , Feminino , Avaliação Geriátrica , Humanos , Masculino , Pessoa de Meia-Idade , Valores de Referência , Limiar Sensorial , Estados UnidosRESUMO
Despite a considerable literature on family care of the elderly, comparatively little attention has been devoted to the ethical dimensions of caring for frail and dependent older family members. Nor is there an extensive literature available to guide family therapists or others in the helping professions who work with families experiencing ethical dilemmas and issues associated with caring for elderly loved ones. The purpose of this paper is to highlight some of the ethical dilemmas families face in caring for an elderly loved one, and to identify several ethical principles that can be used to address these dilemmas. There is an explicit focus on families caring for aged parents afflicted with a dementia such as Alzheimer's disease.
Assuntos
Cuidadores/normas , Demência/enfermagem , Ética , Terapia Familiar , Assistência Domiciliar/normas , Idoso , Doença de Alzheimer/enfermagem , Beneficência , Cuidadores/psicologia , Tomada de Decisões , Assistência Domiciliar/psicologia , Humanos , Relação entre Gerações , Obrigações Morais , Autonomia PessoalRESUMO
Procedures for the introduction of plasmid DNA into Gram-negative bacteria have been adapted and optimized to permit transformation of the plant pathogen Xanthomonas campestris pathovar campestris with the cloning vector pKT230 and other broad-host-range plasmids. The technique involves CaCl2-induced competence and heat shock and is similar to that routinely used for Escherichia coli. Wild-type X. c. campestris strains appear to restrict incoming unmodified DNA, so that plasmid DNA for transformation must be prepared from X. c. campestris (into which it has previously been introduced by conjugation). To overcome this disadvantage a restriction-deficient mutant has been isolated.
Assuntos
DNA Bacteriano/genética , Plasmídeos , Transformação Bacteriana , Xanthomonas/genética , TemperaturaRESUMO
A promoter-probe plasmid suitable for use in Xanthomonas campestris pathovar campestris (causal agent of crucifer black rot) was constructed by ligating a broad host range IncQ replicon into the promoter-probe plasmid pKK232-8, which contains a promoterless chloramphenicol acetyltransferase gene. Xanthomonas chromosomal DNA fragments were 'shotgun' cloned into a restriction site in front of this gene, and the resulting library was transferred en masse into Xanthomonas. Individual transconjugants possessing DNA insertions with promoter activity in plants were identified by virtue of their ability to infect chloramphenicol-treated turnip seedlings. Of 19 transconjugants identified in this way five were chloramphenicol resistant both in turnip seedlings and on agar plates. However the remaining 14 were only chloramphenicol resistant in planta, and thus apparently contained plant-inducible promoter fragments. Resistance to chloramphenicol was correlated with increased chloramphenicol acetyltransferase activity for the transconjugants assayed. The promoter fragments were used to isolate genomic clones from a library, and the role of the genes contained in these clones in pathogenicity is being investigated.
Assuntos
Genes Bacterianos/genética , Doenças das Plantas/microbiologia , Xanthomonas campestris/genética , Brassica napus/genética , Brassica napus/microbiologia , Clonagem Molecular , Sondas de DNA/genética , Doenças das Plantas/genética , Regiões Promotoras Genéticas/genética , Plântula/genética , Plântula/microbiologiaRESUMO
This study explores the grandmother role as experienced by a nonrandom sample of nine lesbian women. It examines how they define the grandmother role, and the behaviors and actions through which they enact the role. During individual interviews each woman was asked to talk about what makes a woman a good grandmother, memories of her own grandmothers, and the relationship she has with one or more of her grandchildren. The effect of her sexual orientation on the relationship was not explored. These women define the grandmother role as providing emotional support to their grandchildren, providing varied experiences for their grandchildren, and providing support for the parents of their grandchildren.
Assuntos
Homossexualidade Feminina , Relação entre Gerações , Papel (figurativo) , Adulto , Feminino , Humanos , Pessoa de Meia-Idade , Saúde da MulherRESUMO
With one exception, all spiroplasma strains examined contained extrachromosomal DNA, most of which was in the form of covalently closed circular plasmids. One plasmid, pIJ2000, carried by Spiroplasma citri strain ASP-1, was purified and characterized and used to probe for related plasmids in other strains. Unsuccessful attempts were made to clone pIJ2000 into Escherichia coli using the vectors pAT153 and pBR322. However, spiroplasma chromosomal DNA fragments could be cloned without difficulty.
Assuntos
DNA Bacteriano/genética , Plasmídeos , Spiroplasma/genética , Clonagem Molecular , DNA Recombinante , DNA Viral/genética , Escherichia coli/genética , Hibridização de Ácido Nucleico , Spiroplasma/isolamento & purificaçãoRESUMO
The synthesis of extracellular enzymes and extracellular polysaccharide (EPS) in Xanthomonas campestris pv. campestris (Xcc) is regulated by a cluster of genes called rpf (for regulation of pathogenicity factors). Two of the genes, rpfF and rpfB, have previously been implicated in the synthesis of a diffusible regulatory molecule, DSF. Here, we describe a screen of transposon insertion mutants of Xcc that identified two DSF-overproducing strains. In each mutant, the gene disrupted is rpfC, which encodes a hybrid two-component regulatory protein in which the sensor and regulator domains are fused and which contains an additional C-terminal phosphorelay (HPt) domain. We show that rpfC is in an operon with rpfH and rpfG. The predicted protein RpfG has a regulatory input domain attached to a specialized version of an HD domain, previously suggested to function in signal transduction. The predicted protein RpfH is structurally related to the sensory input domain of RpfC. We show that RpfC and RpfG act positively to regulate the synthesis of extracellular enzymes and EPS, but that RpfC acts negatively to regulate the synthesis of DSF. We propose that RpfGHC is a signal transduction system that couples the synthesis of pathogenicity factors to sensing of environmental signals that may include DSF itself.
Assuntos
Proteínas de Bactérias/metabolismo , Transdução de Sinais , Xanthomonas campestris/genética , Xanthomonas campestris/patogenicidade , Sequência de Aminoácidos , Proteínas de Bactérias/biossíntese , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Sequência de Bases , Primers do DNA , Elementos de DNA Transponíveis , Dados de Sequência Molecular , Mutagênese , Mutação , RNA Mensageiro/genética , Homologia de Sequência de Aminoácidos , Virulência/genéticaRESUMO
The cosmid clone pIJ3020 containing DNA from the plant pathogenic bacterium Xanthomonas campestris pathovar campestris has previously been shown to complement a non-pathogenic mutant defective in synthesis of extracellular enzymes. The DNA cloned in pIJ3020 was analysed by mutagenesis with Tn5 and Tn5lac and by nucleotide sequencing. The results indicate that this region of the genome contains a cluster of genes, mutation in any of which results in failure of the enzymes and extracellular polysaccharide to be synthesized. The designation rpf (regulation of pathogenicity factors) is proposed for these genes. The nucleotide sequence of one gene (rpfC) predicts a protein product with homology to conserved domains of both sensor and regulator proteins of prokaryotic two-component regulatory systems, which are usually involved in regulating gene expression in response to environmental stimuli.
Assuntos
DNA Bacteriano/genética , Enzimas/biossíntese , Regulação Bacteriana da Expressão Gênica , Regulação Enzimológica da Expressão Gênica , Família Multigênica , Polissacarídeos/biossíntese , Xanthomonas/genética , Sequência de Aminoácidos , Sequência de Bases , Elementos de DNA Transponíveis , Genes Bacterianos , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Regiões Promotoras Genéticas , Homologia de Sequência do Ácido Nucleico , Xanthomonas/enzimologia , Xanthomonas/patogenicidadeRESUMO
A DNA fragment from Xanthomonas campestris pv. campestris that partially restored the carbohydrate fermentation pattern of a cya crp Escherichia coli strain was cloned and expressed in E. coli. The nucleotide sequence of this fragment revealed the presence of a 700-base-pair open reading frame that coded for a protein highly similar to the catabolite activation factor (CAP) of E. coli (accordingly named CLP for CAP-like protein). An X. campestris pv. campestris clp mutant was constructed by reverse genetics. This strain was not affected in the utilization of various carbon sources but had strongly reduced pathogenicity. Production of xanthan gum, pigment, and extracellular enzymes was either increased or decreased, suggesting that CLP plays a role in the regulation of phytopathogenicity.
Assuntos
Proteínas de Bactérias/genética , Proteína Receptora de AMP Cíclico/genética , Xanthomonas/genética , Sequência de Aminoácidos , Sequência de Bases , Clonagem Molecular/métodos , Proteína Receptora de AMP Cíclico/metabolismo , DNA Bacteriano/genética , DNA Bacteriano/isolamento & purificação , Escherichia coli/genética , Escherichia coli/fisiologia , Fermentação , Dados de Sequência Molecular , Plantas/microbiologia , Plasmídeos , Homologia de Sequência do Ácido Nucleico , Virulência/genética , Xanthomonas/patogenicidadeRESUMO
A genomic library was prepared in Escherichia coli from DNA of wild-type Xanthomonas campestris pv. campestris (aetiological agent of crucifer black rot), partially digested with endonuclease EcoRI, using the mobilisable broad host range cosmid vector pLAFR1. Recombinant plasmids contained inserts ranging in size from 19.1 to 32.3 kb (mean 26.6). Certain of the clones complemented E. coli auxotrophic markers. Using the narrow host range plasmid pRK2013 as a helper the pooled recombinant plasmids were transferred conjugally to X. c. campestris mutants, and clones were identified which restored yellow pigmentation to white mutants, prototrophy to amino acid auxotrophs and pathogenicity towards turnip plants to two non-pathogenic mutants. The lesion in one mutant (8288, complemented by the plasmid pIJ3000) is unknown. However mutant 8237 is defective in production of extracellular protease and polygalacturonate lyase and restoration of pathogenicity by complementation with the plasmid pIJ3020 concomitantly restored both enzyme levels to wild-type values.