RESUMO
This paper examines the intersection of dementia with the physiological processes and social contexts of old age; assesses the current legal response to problems arising through that intersection; and considers the potentially transformative effect of re-thinking legal response with those contextualised problems in mind. Two distinctive problems are identified: a heightened risk of exploitation, and an increasingly intense need for care coinciding with a decreasing ability to recognise and respond to that need. These problems require a social (rather than medical) response, of which law is an integral part. Several areas of law (including adult guardianship, legislation and common law doctrine relating to health care consent/refusal, and the body of law relating to decision-making about agreements, transactions, and bequests) provide for that response through the medico-legal construct of mental capacity. This legal idea of mental capacity has survived extensive critique, particularly in relation to interpretation and implementation of Article 12 of the Convention on the Rights of Persons With Disabilities. The survival of the mental capacity construct can be attributed to its usefulness as a theoretical mechanism that provides both a justification for over-ruling choice and preference (locating autonomy in the mentally capable decision) and a process for doing so (the mental capacity assessment and determination). This ambit of usefulness is particularly relevant to the problems (arising in the context of dementia in old age) identified in this paper. Both problems engage the public interest, together with the fundamental legal principle of fairness, in ways that call for legal response of some kind. Supported decision-making, as the suggested replacement for mental capacity based legal response, applies awkwardly in these contexts; as far as the individual is concerned, her decision has been made (and she does not need assistance in making one). This paper concludes that the mental capacity construct is problematic both for the reasons identified in the CRPD discourse (in which the experience of dementia in old age has been largely invisible) and because of the complicated intersections between mental capacity, dementia, and old age. The paper concludes by setting out an alternative conceptual basis and framework for legal response, including over-ruling expressed choice and preference, constructed around a principled theory of vulnerability as an alternative to and replacement for the mental capacity construct.
Assuntos
Tomada de Decisões , Demência/psicologia , Competência Mental , Envelhecimento/fisiologia , Envelhecimento/psicologia , Pessoas com Deficiência/legislação & jurisprudência , Direitos Humanos/legislação & jurisprudência , Humanos , Competência Mental/legislação & jurisprudência , Apoio Social , Populações Vulneráveis/legislação & jurisprudênciaRESUMO
Sinorhizobium fredii HH103 is a fast-growing rhizobial strain infecting a broad range of legumes including both American and Asiatic soybeans. In this work, we present the sequencing and annotation of the HH103 genome (7.25 Mb), consisting of one chromosome and six plasmids and representing the structurally most complex sinorhizobial genome sequenced so far. Comparative genomic analyses of S. fredii HH103 with strains USDA257 and NGR234 showed that the core genome of these three strains contains 4,212 genes (61.7% of the HH103 genes). Synteny plot analysis revealed that the much larger chromosome of USDA257 (6.48 Mb) is colinear to the HH103 (4.3 Mb) and NGR324 chromosomes (3.9 Mb). An additional region of the USDA257 chromosome of about 2 Mb displays similarity to plasmid pSfHH103e. Remarkable differences exist between HH103 and NGR234 concerning nod genes, flavonoid effect on surface polysaccharide production, and quorum-sensing systems. Furthermore a number of protein secretion systems have been found. Two genes coding for putative type III-secreted effectors not previously described in S. fredii, nopI and gunA, have been located on the HH103 genome. These differences could be important to understand the different symbiotic behavior of S. fredii strains HH103, USDA257, and NGR234 with soybean.
Assuntos
Genoma Bacteriano , Glycine max/microbiologia , Sinorhizobium fredii/genética , Genes Bacterianos , Dados de Sequência Molecular , Fixação de Nitrogênio/genética , Raízes de Plantas/microbiologia , Polissacarídeos Bacterianos/genética , Percepção de Quorum , Sinorhizobium fredii/fisiologia , Simbiose/genéticaRESUMO
Here we report that the structure of the Sinorhizobium fredii HH103 exopolysaccharide (EPS) is composed of glucose, galactose, glucuronic acid, pyruvic acid, in the ratios 5â¶2â¶2â¶1 and is partially acetylated. A S. fredii HH103 exoA mutant (SVQ530), unable to produce EPS, not only forms nitrogen fixing nodules with soybean but also shows increased competitive capacity for nodule occupancy. Mutant SVQ530 is, however, less competitive to nodulate Vigna unguiculata. Biofilm formation was reduced in mutant SVQ530 but increased in an EPS overproducing mutant. Mutant SVQ530 was impaired in surface motility and showed higher osmosensitivity compared to its wild type strain in media containing 50 mM NaCl or 5% (w/v) sucrose. Neither S. fredii HH103 nor 41 other S. fredii strains were recognized by soybean lectin (SBL). S. fredii HH103 mutants affected in exopolysaccharides (EPS), lipopolysaccharides (LPS), cyclic glucans (CG) or capsular polysaccharides (KPS) were not significantly impaired in their soybean-root attachment capacity, suggesting that these surface polysaccharides might not be relevant in early attachment to soybean roots. These results also indicate that the molecular mechanisms involved in S. fredii attachment to soybean roots might be different to those operating in Bradyrhizobium japonicum.
Assuntos
Fixação de Nitrogênio , Polissacarídeos Bacterianos/química , Sinorhizobium fredii/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Sequência de Carboidratos , Fabaceae/microbiologia , Glicosiltransferases/genética , Glicosiltransferases/metabolismo , Dados de Sequência Molecular , Mutação , Pressão Osmótica , Polissacarídeos Bacterianos/metabolismo , Sinorhizobium fredii/genética , Sinorhizobium fredii/fisiologia , SimbioseRESUMO
In this work we have characterised the Sinorhizobium fredii HH103 greA lpsB lpsCDE genetic region and analysed for the first time the symbiotic performance of Sinorhizobium fredii lps mutants on soybean. The organization of the S. fredii HH103 greA, lpsB, and lpsCDE genes was equal to that of Sinorhizobium meliloti 1021. S. fredii HH103 greA, lpsB, and lpsE mutant derivatives produced altered LPS profiles that were characteristic of the gene mutated. In addition, S. fredii HH103 greA mutants showed a reduction in bacterial mobility and an increase of auto-agglutination in liquid cultures. RT-PCR and qPCR experiments demonstrated that the HH103 greA gene has a positive effect on the transcription of lpsB. Soybean plants inoculated with HH103 greA, lpsB or lpsE mutants formed numerous ineffective pseudonodules and showed severe symptoms of nitrogen starvation. However, HH103 greA and lps mutants were also able to induce the formation of a reduced number of soybean nodules of normal external morphology, allowing the possibility of studying the importance of bacterial LPS in later stages of the S. fredii HH103-soybean symbiosis. The infected cells of these nodules showed signs of early termination of symbiosis and lytical clearance of bacteroids. These cells also had very thick walls and accumulation of phenolic-like compounds, pointing to induced defense reactions. Our results show the importance of bacterial LPS in later stages of the S. fredii HH103-soybean symbiosis and their role in preventing host cell defense reactions. S. fredii HH103 lpsB mutants also showed reduced nodulation with Vigna unguiculata, although the symbiotic impairment was less pronounced than in soybean.
Assuntos
Glycine max/microbiologia , Glycine max/fisiologia , Lipopolissacarídeos/metabolismo , Nodulação , Sinorhizobium fredii/metabolismo , Simbiose , Genes Bacterianos/genética , Mutação , Sinorhizobium fredii/genética , Sinorhizobium fredii/fisiologia , Fatores de Tempo , Transcrição GênicaRESUMO
Sinorhizobium fredii HH103 is a fast-growing rhizobial strain that is able to nodulate legumes that develop determinate nodules, e.g., soybean, and legumes that form nodules of the indeterminate type. Here we present the genome of HH103, which consists of one chromosome and five plasmids with a total size of 7.22 Mb.
Assuntos
DNA Bacteriano/química , DNA Bacteriano/genética , Genoma Bacteriano , Sinorhizobium fredii/genética , Cromossomos Bacterianos , Dados de Sequência Molecular , Plasmídeos , Análise de Sequência de DNA , Sinorhizobium fredii/isolamento & purificação , Sinorhizobium fredii/fisiologia , Glycine max/microbiologia , SimbioseRESUMO
The Sinorhizobium fredii HH103 rkp-3 region has been isolated and sequenced. Based on the similarities between the S. fredii HH103 rkpL, rkpM, rkpN, rkpO, rkpP, and rkpQ genes and their corresponding orthologues in Helicobacter pylori, we propose a possible pathway for the biosynthesis of the S. fredii HH103 K-antigen polysaccharide (KPS) repeating unit. Three rkp-3 genes (rkpM, rkpP, and rkpQ) involved in the biosynthesis of the HH103 KPS repeating unit (a derivative of the pseudaminic acid) have been mutated and analyzed. All the rkp-3 mutants failed to produce KPS and their lipopolysaccharide (LPS) profiles were altered. These mutants showed reduced motility and auto-agglutinated when early-stationary cultures were further incubated under static conditions. Glycine max, Vigna unguiculata (determinate nodule-forming legumes), and Cajanus cajan (indeterminate nodules) plants inoculated with mutants in rkpM, rkpQ, or rkpP only formed pseudonodules that did not fix nitrogen and were devoid of bacteria. In contrast, another indeterminate nodule-forming legume, Glycyrrhiza uralensis, was still able to form some nitrogen-fixing nodules with the three S. fredii HH103 rifampicin-resistant rkp-3 mutants tested. Our results suggest that the severe symbiotic impairment of the S. fredii rkp-3 mutants with soybean, V. unguiculata, and C. cajan is mainly due to the LPS alterations rather than to the incapacity to produce KPS.
Assuntos
Antígenos de Bactérias/biossíntese , Glycine max/microbiologia , Lipopolissacarídeos/metabolismo , Polissacarídeos Bacterianos/biossíntese , Sinorhizobium fredii/genética , Sinorhizobium fredii/metabolismo , Antígenos de Bactérias/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Configuração de Carboidratos , Regulação Bacteriana da Expressão Gênica/fisiologia , Concentração de Íons de Hidrogênio , Lipopolissacarídeos/química , Lipopolissacarídeos/genética , Nodulação/fisiologia , Raízes de Plantas/microbiologia , Polissacarídeos Bacterianos/genéticaRESUMO
Glycine max (soybean) plants can be nodulated by fast-growing rhizobial strains of the genus Sinorhizobium as well as by slow-growing strains clustered in the genus Bradyrhizobium. Fast-growing rhizobia strains with different soybean cultivar specificities have been isolated from Chinese soils and from other geographical regions. Most of these strains have been clustered into the species Sinorhizobium fredii. The S. fredii strain HH103 was isolated from soils of Hubei province, Central China and was first described in 1985. This strain is capable to nodulate American and Asiatic soybean cultivars and many other different legumes and is so far the best studied fast-growing soybean-nodulating strain. Additionally to the chromosome S. fredii HH103 carries five indigenous plasmids. The largest plasmid (pSfrHH103e) harbours genes for the production of diverse surface polysaccharides, such as exopolysaccharides (EPS), lipopolysaccharides (LPS), and capsular polysaccharides (KPS). The second largest plasmid (pSfrHH103d) is a typical symbiotic plasmid (pSym), carrying nodulation and nitrogen fixation genes. The present mini review focuses on symbiotic properties of S. fredii HH103, in particular on nodulation and surface polysaccharides aspects. The model strain S. fredii HH103 was chosen for genomic sequencing, which is currently in progress. First analyses of the draft genome sequence revealed an extensive synteny between the chromosomes of S. fredii HH103 and Rhizobium sp. NGR234.
Assuntos
Genoma Bacteriano , Sinorhizobium fredii/fisiologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/fisiologia , Genômica/métodos , Sinorhizobium fredii/genética , Glycine max/microbiologia , Simbiose/genética , Simbiose/fisiologiaRESUMO
In this work, the role of the rkpU and rkpJ genes in the production of the K-antigen polysaccharides (KPS) and in the symbiotic capacity of Sinorhizobium fredii HH103, a broad host-range rhizobial strain able to nodulate soybean and many other legumes, was studied. The rkpJ- and rkpU-encoded products are orthologous to Escherichia coli proteins involved in capsule export. S. fredii HH103 mutant derivatives were contructed in both genes. To our knowledge, this is the first time that the role of rkpU in KPS production has been studied in rhizobia. Both rkpJ and rkpU mutants were unable to produce KPS. The rkpU derivative also showed alterations in its lipopolysaccharide (LPS). Neither KPS production nor rkpJ and rkpU expression was affected by the presence of the flavonoid genistein. Soybean (Glycine max) plants inoculated with the S. fredii HH103 rkpU and rkpJ mutants showed reduced nodulation and clear symptoms of nitrogen starvation. However, neither the rkpJ nor the rkpU mutants were significantly impaired in their symbiotic interaction with cowpea (Vigna unguiculata). Thus, we demonstrate for the first time to our knowledge the involvement of the rkpU gene in rhizobial KPS production and also show that the symbiotic relevance of the S. fredii HH103 KPS depends on the specific bacterium-legume interaction.
Assuntos
Glycine max/microbiologia , Nodulação , Polissacarídeos Bacterianos/biossíntese , Sinorhizobium fredii/genética , Simbiose , Antígenos de Bactérias/biossíntese , DNA Bacteriano/genética , Fabaceae/microbiologia , Genes Bacterianos , Teste de Complementação Genética , Genisteína/farmacologia , Mutação , Sinorhizobium fredii/crescimento & desenvolvimento , Sinorhizobium fredii/metabolismo , Especificidade da EspécieRESUMO
O objetivo foi validar o Fatigue Pictogram para uso no Brasil. Os dados foram coletados em quatro ambulatórios de oncologia de São Paulo (SP) e na Escola de Enfermagem da USP. A amostra de conveniência envolveu 584 pacientes com câncer, 184 acompanhantes e 189 estudantes de graduação enfermagem, que responderam ao Pictograma de Fadiga, ao Inventário de Depressão de Beck (IDB) e Escala de Karnofsky (KPS). Foram feitos testes de validade e confiabilidade. O Teste-reteste mostrou que o instrumento tem boa estabilidade. O primeiro item do Pictograma de Fadiga discriminou estudantes de cuidadores de pacientes, mas não pacientes de cuidadores. O segundo item discriminou todos os grupos. Observou-se adequada validade convergente (fadiga e depressão) e divergente (fadiga e Karnofsky). O Pictograma de Fadiga é válido, confiável e fácil de usar para avaliar fadiga em câncer, mas necessita ajustes para uso em pessoas saudáveis.
The purpose of this paper was to validate the Fatigue Pictogram for use in Brazil. Data was collected at four oncology ambulatory clinics in Sao Paulo (Brazil) and at the Nursing School of Sao Paulo University. A convenience sample of 584 cancer patients, 184 caregivers and 189 undergraduate nursing students completed the Karnofsky Scale, Fatigue Pictogram-Brazilian Version, and the Beck Depression Inventory (BDI). Validity and reliability tests were performed. Test-retest showed that the instrument has good stability. The first item of the Fatigue Pictogram discriminated students from caregivers and patients but not patients from caregivers. The second item discriminated among all groups. Adequate convergent (fatigue and depression) and divergent (fatigue and Karnofsky Scale) validity was observed. The Fatigue Pictogram is a valid, reliable, and easy-to-use tool for assessment of cancer-related fatigue but needs adjustments for use among healthy individuals.
El objetivo fue validar el Pictograma de Fatiga para su uso en Brasil. Los datos fueron recolectados en cuatro clínicas de oncología ambulatoria de São Paulo (SP) y la Escuela de Enfermería de la USP. La muestra de conveniencia incluyó 584 pacientes con cáncer, 184 acompañantes y 189 es tudiantes de posgrado en enfermería, que respondieran a la Pictograma de Fatiga, el Inventario de Depresión de Beck (BDI) y la escala de Karnofsky (KPS). Realizadas pruebas de validez y fiabilidad. Test-retest mostró que el instrumento tiene una buena estabilidad. El primer item del Pictograma de Fatiga discriminó estudiantes de los cuidadores de los pacientes, pero no los pacientes de los cuidadores. El segun item discriminó todos los grupos. Hubo suficiente validez convergente (fatiga y depresión) y divergente(Karnofsky y fatiga). Pictograma de Fatiga es válida, fiable y fácil de utilizar para evaluar la fatiga en el cáncer, pero necesita ajustes para el uso en personas sanas.
Assuntos
Humanos , Estudo de Validação , Fadiga , Neoplasias , Reprodutibilidade dos TestesRESUMO
Megaplasmid pSymB of the nitrogen-fixing symbiont Sinorhizobium meliloti, implicated in adaptation to hyperosmotic stress, contains 11 gene clusters that apparently encode surface polysaccharides. However, only 2 of these clusters, containing the exo and exp genes, have been associated with the synthesis of the acidic exopolysaccharides succinoglycan and galactoglucan, respectively. The functions of the other 9 clusters remain unsolved. The involvement of one of those regions, pSymB cluster 3, on surface polysaccharide synthesis and its possible implication in osmoadaptation were investigated. In silico analysis of cluster 3 showed that it putatively encodes for the synthesis and transport of a methylated surface polysaccharide. Mutants affected in this cluster were symbiotically effective but showed defects in growth under saline and nonsaline osmotic stress. The gene SMb21071, encoding a putative initiating glycosyltransferase, is transcriptionally induced under hyperosmotic conditions. Sodium dodecyl sulfate - polyacrylamide gel electrophoresis and silver staining showed that osmotic stresses changed the profiles of surface polysaccharides of wild-type and mutants strains in different ways. The overall results suggest that cluster 3 is important for growth under saline stress and essential for growth under nonsaline hyperosmotic stress, and it appears to be implicated in maintaining and (or) modifying surface polysaccharides in response to osmotic stress.
Assuntos
Genes Bacterianos , Polissacarídeos Bacterianos/metabolismo , Sinorhizobium meliloti/genética , Sinorhizobium meliloti/metabolismo , Adaptação Fisiológica/genética , Sequência de Bases , Membrana Celular/metabolismo , DNA Bacteriano/genética , Glicosiltransferases/genética , Glicosiltransferases/metabolismo , Família Multigênica , Mutação , Concentração Osmolar , Pressão Osmótica , Plasmídeos/genética , Polissacarídeos Bacterianos/química , Polissacarídeos Bacterianos/genéticaRESUMO
In 2000, with the implementation of Part III of the Adult Guardianship Act: Support and Assistance for Abused and Neglected Adults, British Columbia formally recognized the need to examine issues of decisional capacity of older adults within a context of abuse or neglect. Interestingly, however, although the test of capacity was clearly laid out under this piece of legislation, the potential influence that living in a situation of abuse or neglect may have on how the person makes decisions is not explicitly addressed. Similarly, this is a missing link throughout the literature discussing decisional capacity in older adults. This gap exists despite the fact that determining the "protection" needs of someone who is being abused and/or neglected often hinges directly on that person's decisional capacity. The purpose of this article is to examine the unique aspects associated with assessing and determining capacity for older adults who are living in a situation of abuse or neglect. The specific objectives are to: (a) examine how living in a situation of abuse or neglect may influence the determination of capacity and (b) explore the implications of conducting an assessment within a potentially abusive context. The legal notion of undue influence and the psychological concept of relational connection are introduced as potentially important for considering decision making within this context.
Assuntos
Abuso de Idosos/psicologia , Avaliação Geriátrica/métodos , Relações Interpessoais , Maus-Tratos Conjugais/psicologia , Atividades Cotidianas , Idoso , Colúmbia Britânica , Abuso de Idosos/diagnóstico , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Autocuidado/métodos , Populações Vulneráveis/estatística & dados numéricosRESUMO
Sinorhizobium fredii HH103 produces cyclic beta glucans (CG) composed of 18 to 24 glucose residues without or with 1-phosphoglycerol as the only substituent. The S. fredii HH103-Rifr cgs gene (formerly known as ndvB) was sequenced and mutated with the lacZ-gentamicin resistance cassette. Mutant SVQ562 did not produce CG, was immobile, and grew more slowly in the hypoosmotic GYM medium, but its survival in distilled water was equal to that of HH103-Rifr. Lipopolysaccharides and K-antigen polysaccharides produced by SVQ562 were not apparently altered. SVQ562 overproduced exopolysaccharides (EPS) and its exoA gene was transcribed at higher levels than in HH103-Rifr. In GYM medium, the EPS produced by SVQ562 was of higher molecular weight and carried higher levels of substituents than that produced by HH103-Rifr. The expression of the SVQ562 cgsColon, two colonslacZ fusion was influenced by the pH and the osmolarity of the growth medium. The S. fredii cgs mutants SVQ561 (carrying cgs::Omega) and SVQ562 only formed pseudonodules on Glycine max (determinate nodules) and on Glycyrrhiza uralensis (indeterminate nodules). Although nodulation factors were detected in SVQ561 cultures, none of the cgs mutants induced any macroscopic response in Vigna unguiculata roots. Thus, the nodulation process induced by S. fredii cgs mutants is aborted at earlier stages in V. unguiculata than in Glycine max.
Assuntos
Proteínas de Bactérias/genética , Mutação , Polissacarídeos Bacterianos/metabolismo , Nódulos Radiculares de Plantas/crescimento & desenvolvimento , Sinorhizobium fredii/genética , Proteínas de Bactérias/metabolismo , DNA de Plantas/química , DNA de Plantas/genética , Flavonoides/farmacologia , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Teste de Complementação Genética , Glycyrrhiza uralensis/crescimento & desenvolvimento , Glycyrrhiza uralensis/microbiologia , Interações Hospedeiro-Patógeno , Concentração de Íons de Hidrogênio , Espectroscopia de Ressonância Magnética , Dados de Sequência Molecular , Polissacarídeos Bacterianos/análise , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Nódulos Radiculares de Plantas/microbiologia , Análise de Sequência de DNA , Sinorhizobium fredii/metabolismo , Sinorhizobium fredii/fisiologia , Cloreto de Sódio/farmacologia , Glycine max/crescimento & desenvolvimento , Glycine max/microbiologia , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , beta-Glucanas/análise , beta-Glucanas/metabolismoRESUMO
Transposon Tn5-Mob mutagenesis allowed the selection of a Sinorhizobium fredii HH103 mutant derivative (SVQ 292) that requires the presence of uracil to grow in minimal media. The mutated gene, pyrF, codes for an orotidine-5 - monophosphate decarboxylase (EC 4.1.1.23). Mutant SVQ 292 and its parental prototrophic mutant HH103 showed similar Nod-factor and lipopolysaccharide profiles. The symbiotic properties of mutant SVQ 292 were severely impaired with all legumes tested. Mutant SVQ 292 formed small ineffective nodules on Cajanus cajan and abnormal nodules (pseudonodules) unable to fix nitrogen on Glycine max (soybean), Macroptitlium atropurpureum, Indigofera tinctoria, and Desmodium canadense. It also did not induce any macroscopic response in Macrotyloma axillare roots. The symbiotic capacity of SVQ 292 with soybean was not enhanced by the addition of uracil to the plant nutritive solution.
Assuntos
Regulação Bacteriana da Expressão Gênica , Glycine max/microbiologia , Mutação , Orotidina-5'-Fosfato Descarboxilase/genética , Sinorhizobium fredii/crescimento & desenvolvimento , Simbiose , Sequência de Aminoácidos , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Fabaceae/microbiologia , Orotidina-5'-Fosfato Descarboxilase/química , Orotidina-5'-Fosfato Descarboxilase/metabolismo , Alinhamento de Sequência , Sinorhizobium fredii/enzimologia , Sinorhizobium fredii/genética , Simbiose/genética , Uracila/metabolismoRESUMO
Transposon Tn5-Mob mutagenesis allowed the selection of a Sinorhizobium fredii HH103 mutant derivative (SVQ 292) that requires the presence of uracil to grow in minimal media. The mutated gene, pyrF, codes for an orotidine-5 - monophosphate decarboxylase (EC 4.1.1.23). Mutant SVQ 292 and its parental prototrophic mutant HH103 showed similar Nod-factor and lipopolysaccharide profiles. The symbiotic properties of mutant SVQ 292 were severely impaired with all legumes tested. Mutant SVQ 292 formed small ineffective nodules on Cajanus cajan and abnormal nodules (pseudonodules) unable to fix nitrogen on Glycine max (soybean), Macroptitlium atropurpureum, Indigofera tinctoria, and Desmodium canadense. It also did not induce any macroscopic response in Macrotyloma axillare roots. The symbiotic capacity of SVQ 292 with soybean was not enhanced by the addition of uracil to the plant nutritive solution (AU)
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Assuntos
Sinorhizobium fredii/genética , Fabaceae/genética , Mutação , Simbiose/genética , Oligossacarídeos/genética , Mutação/genéticaRESUMO
The Sinorhizobium fredii HH103 rkp-1 region, which is involved in capsular polysaccharides (KPS) production, was isolated and sequenced. The organization of the S. fredii genes identified, rkpUAGHIJ and kpsF3, was identical to that described for S. meliloti 1021 but different from that of S. meliloti AK631. The long rkpA gene (7.5 kb) of S. fredii HH103 and S. meliloti 1021 appears as a fusion of six clustered AK631 genes, rkpABCDEF. S. fredii HH103-Rif(r) mutants affected in rkpH or rkpG were constructed. An exoA mutant unable to produce exopolysaccharide (EPS) and a double mutant exoA rkpH also were obtained. Glycine max (soybean) and Cajanus cajan (pigeon pea) plants inoculated with the rkpH, rkpG, and rkpH exoA derivatives of S. fredii HH103 showed reduced nodulation and severe symptoms of nitrogen starvation. The symbiotic capacity of the exoA mutant was not significantly altered. All these results indicate that KPS, but not EPS, is of crucial importance for the symbiotic capacity of S. fredii HH103-Rif(r). S. meliloti strains that produce only EPS or KPS are still effective with alfalfa. In S. fredii HH103, however, EPS and KPS are not equivalent, because mutants in rkp genes are symbiotically impaired regardless of whether or not EPS is produced.