Genetic diversity of symbiotic Bradyrhizobium elkanii populations recovered from inoculated and non-inoculated Acacia mangium field trials in Brazil.

Acacia mangium is a legume tree native to Australasia. Since the eighties, it has been introduced into many tropical countries, especially in a context of industrial plantations. Many field trials have been set up to test the effects of controlled inoculation with selected symbiotic bacteria versus natural colonization with indigenous strains. In the introduction areas, A. mangium trees spontaneously nodulate with local and often ineffective bacteria. When inoculated, the persistence of inoculants and possible genetic recombination with local strains remain to be explored. The aim of this study was to describe the genetic diversity of bacteria spontaneously nodulating A. mangium in Brazil and to evaluate the persistence of selected strains used as inoculants. Three different sites, several hundred kilometers apart, were studied, with inoculated and non-inoculated plots in two of them. Seventy-nine strains were isolated from nodules and sequenced on three housekeeping genes (glnII, dnaK and recA) and one symbiotic gene (nodA). All but one of the strains belonged to the Bradyrhizobium elkanii species. A single case of housekeeping gene transfer was detected among the 79 strains, suggesting an extremely low rate of recombination within B. elkanii, whereas the nodulation gene nodA was found to be frequently transferred. The fate of the inoculant strains varied depending on the site, with a complete disappearance in one case, and persistence in another. We compared our results with the sister species Bradyrhizobium japonicum, both in terms of population genetics and inoculant strain destiny.

Arbuscular mycorrhizal colonization and nodulation improve flooding tolerance in Pterocarpus officinalis Jacq. seedlings.

Pterocarpus officinalis (Jacq.) seedlings inoculated with the arbuscular mycorrhizal fungus, Glomus intraradices, and the strain of Bradyrhizobium sp. (UAG 11A) were grown under stem-flooded or nonflooded conditions for 13 weeks after 4 weeks of nonflooded pretreatment under greenhouse conditions. Flooding of P. officinalis seedlings induced several morphological and physiological adaptive mechanisms, including formation of hypertrophied lenticels and aerenchyma tissue and production of adventitious roots on submerged portions of the stem. Flooding also resulted in an increase in collar diameter and leaf, stem, root, and total dry weights, regardless of inoculation. Under flooding, arbuscular mycorrhizas were well developed on root systems and adventitious roots compared with inoculated root systems under nonflooding condition. Arbuscular mycorrhizas made noteworthy contributions to the flood tolerance of P. officinalis seedlings by improving plant growth and P acquisition in leaves. We report in this study the novel occurrence of nodules connected vascularly to the stem and nodule and arbuscular mycorrhizas on adventitious roots of P. officinalis seedlings. Root nodules appeared more efficient fixing N(2) than stem nodules were. Beneficial effect of nodulation in terms of total dry weight and N acquisition in leaves was particularly noted in seedlings growing under flooding conditions. There was no additive effect of arbuscular mycorrhizas and nodulation on plant growth and nutrition in either flooding treatment. The results suggest that the development of adventitious roots, aerenchyma tissue, and hypertrophied lenticels may play a major role in flooded tolerance of P. officinalis symbiosis by increasing oxygen diffusion to the submerged part of the stem and root zone, and therefore contribute to plant growth and nutrition.

Avaliaçäo dos gânglios regionais do carcinoma epidermóide do pênis (CEP) através de um índice de risco / Evaluation of the regional lymphatic nodes in epidermoid carcinoma of the penis (CEP) by of the risk index

O objetivo desse estudo foi investigar a validade de um índice de risco (IR) no prognóstico de metástases ganglionares no carcinoma epidermóide do pênis (CEP). Foram analisados 53 pacientes com CEP atendidos no Hospital das Clínicas da FMRP-USP, de janeiro de 1978 a dezembro de 1995. A idade variou de 32 a 97 anos. Os tumores foram graduados de acordo com a classificaçäo de Broders e estadiados retrospectivamente (TNM 1999). O IR foi determinado pela soma de TeG (IR = T+G). A linfadenectomia inguinal bilateral (LD) foi indicada naqueles que apresentaram gânglios suspeitos após a antibioticoterapia ou que vieram apresentar alteraçöes durante o período de observaçäo. Faleceram 17 pacientes; A LD foi realizada em 14 pacientes e os 39 restantes permaneceram em observaçäo clínica, sendo que em 8 deles foi feito LD após tempo mediano de 9 meses. Dos pacientes com índice de risco 2 e 3 92 por cento e 80 por cento respectivamente näo apresentavam metastase ganglionar, ao passo que a totalidade daqueles com IR=6 tinha gânglios comprometidos. A associaçäo dos grupos 2 e 3, comparada ao conjunto 4, 5 e 6, mostrou percentual maior de comprometimento nestes últimos (p = 0,0046). Dos 36 pacientes inicialmente No, 27 apresentavam IR 2 ou 3, dos quais 5 evoluíram para N+ (19 por cento); os 9 restantes eram IR >/= 4 e 3 também evoluíram para N+ (33 por cento). Apesar da diferença, näo houve significância estatística entre eles (p = 0,3837). Embora tenha ocorrido maior comprometimento naqueles com IR >/= 4, o índice de risco näo foi capaz de identificar previamente pacientes que evoluíram para N+.

[Bacterial meningitis - diagnosis and treatment] / Meningites bacterianas - diagnóstico e conduta.

OBJECTIVE: To present new concepts on diagnosis and treatment of bacterial meningitis regarding etiologic agents, pathophysiology and options about antimicrobial, antiinflammatory and supportive therapy. METHODS: Bibliographic review from MEDLINE data including articles published during the last ten years. One classic article published before this period and chapters of textbooks on infectious diseases were also included. RESULTS: Initial empirical antibiotic therapy is chosen according to probable etiologic agents for the age group. In the CSF microbiological analysis, the gram stains can reveal bacteria in 50% to 80% of the cases and the culture in nearly 85%. The tests for detection of bacterial antigens are useful for the diagnosis but they present low sensitivity. The most common agents during the neonatal period continue to be E. coli, Streptococcus B and L. monocytogenes. Beyond this period, the incidence of meningitis by Haemophilus influenzae b had a significant decrease after the introduction of conjugate vaccines. However, S. pneumoniae and N. meningitidis continue to be frequent agents. Currently, the thirdgeneration cephalosporins, ceftriaxone or cefotaxime, are the antibiotic therapy of choice. They are used with ampicillin up to two months of life and alone beyond this age. Dexamethasone has showed to be effective in reducing the inflammatory response and the sequelae, mainly the auditory sequelae. The fluid restriction doesn't offer advantages in the supportive care. CONCLUSIONS: Early diagnosis and prompt treatment are related to good outcome. The new insights on pathophysiology, the new antibiotics and the increasing bacterial resistance have determined changes in treatment.

[Study of 176 HIV-seropositive children in Santa Catarina State]. / Estudo de 176 crianças soropositivas para o HIV em Santa Catarina.

OBJECTIVE: The incidence of the acquired immunodeficiency syndrome (AIDS) has increased in Santa Catarina State in Brazil over the last years, with a high number of infected women and children. The purpose of this study was to establish the main characteristics of the children from this State whose HIV serologic tests were positive. METHODS: This was a descriptive study of 176 children with positive serologic tests to HIV, conducted in the Hospital Infantil Joana de Gusmão, Florianópolis City, Santa Catarina State, Brazil. RESULTS: Most of the children (105 cases, 59.6%) were born in Florianópolis, Capital of Santa Catarina State, and Itajaí (22 cases, 12.5%). Vertical transmission of HIV was observed in 167 patients (94.9%). Among 167 HIV-positive mothers, 77 (46.1%) of them acquired the virus by sexual transmission and 35 (21.0%) by use of injectable drugs. However, among 89 HIV-positive fathers, 63 (70.7%) of them used to take drugs. The average age of the HIV-positive children whose serologic tests became negative was 10.5 months. Among 103 symptomatic patients, 87 (84.5%) presented hepatomegaly, 81 (78.6%) lymphadenopathy, 66 (64.0%) splenomegaly, 59 (57.3%) skin bruises, 54 (52.4%) recurrent bronchopneumonia and 50 cases (48.5%) recurrent diarrhea. The most frequent opportunistic infection was mucocutaneous candidiasis that occurred in 41 children (39.8%). CONCLUSIONS: The characteristics were similar to those reported in the literature. A great concentration of HIV infected persons was observed in the coast area where there are three harbor towns, an elevated number of injectable drug users and presence of many tourists.

Nitrogen-fixing stem nodules of the Legume, Discolobium pulchellum Benth.

We report on the structure of N2 -fixing nodules formed on the stem of Discolobium pulchellum Benth., an aquatic legume in the subfamily Pupilionoideae, tribe Aeschynomeneae, from the Hooded areas in the 'Pantanal Matogrossense' region of Brazil. The stern (and root) nodules were obligately aquatic, requiring permanent submergence in water or flooded soil, and receive oxygen via profuse aerenchyma covering The lower stem. Of the 69 isolates of rhizobia isolated from stem and root nodules, 70% were fast-growing acid producers and 38% were slow growers. The rhizobia were not photosynthetic. Nodules were connected to the stem, and the vascular system from the stem branched throughout the nodule, penetrating the infected, tissue within finger-like ingrowths of cortex. In both stem and root nodules, infected tissue was aeschynomenoid or desmodioid, that is, without uninfected (interstitial) cells. The infected cells in stem nodules were vacuolate, with visible infection threads. The inner cortex was rich in amyloplasts and contained the components of an oxygen diffusion barrier (a boundary cell layer without intercellular spaces and glycoprotein occlusions of intercellular spaces in other cell layers). The mid-cortex, external to the boundary layer, consisted of loosely-packed cells and these were continuous with stem aerenchyma. The outer part of the nodules was made up of phellogen-derived cells forming a periderm, or 'corky' layer of cells. The periderm formed large lenticels above cortical vascular bundles. These lenticels also connected with the stem aerenchyma. Root nodules differed only in that infected cells were not vacuolate, bacteroids were larger and contained more poly-ß-hydroxybutyrate (PHB) and there was less aerenchyma/lenticellular tissue. Stem and root nodule structure is discussed in terms of adaptations to O2 constraints in an aquatic environment.

Transcription of the Azospirillum brasilense nifH gene is positively regulated by NifA and NtrA and is negatively controlled by the cellular nitrogen status.

The expression of a translational Azospirillum brasilense nifH-uidA fusion was studied in A. brasilense and in Rhizobium meliloti strains with mutations in nifA, ntrA and ntrC. Induction of the fusion was observed in the R. meliloti wild-type and NtrC- strains on incubation under microaerobic conditions but not in the NifA- and NtrA- strains, showing the absolute requirement of both sigma 54 and NifA for activation of the nifH promoter. Histochemical analysis of the root nodules elicited by R. meliloti wild-type showed expression of the fusion in the late symbiotic zone but not in the meristematic and the early symbiotic zones. No induction of the nifH-uidA fusion was observed in the R. meliloti wild-type or NifA- strains incubated aerobically in nitrogen-free medium, indicating that, in contrast to R. meliloti nifH, A. brasilense nifH cannot be activated directly by NtrC. Expression of the nifH gene in A. brasilense only occurs under nitrogen-limiting, microaerobic conditions, suggesting the presence of a nitrogen-dependent control system for nif gene expression.

Occurrence of nodulation in the Leguminosae.

Reports of nodulation in the Leguminosae are examined in the light of current views on the taxonomy of the family. In the subfamily Caesalpinioideae, nodulation is largely restricted to the tribe Caesalpinieae and the genus Chamaecrista from the Cassieae. All nodules studied have rhizobia retained within infection threads during the nitrogen fixing period. In the Mimosoideae, nodulation is general, except for 4 groups within the tribe Mimoseae, and a very few species of Acacia. The only tribe from the Papilionoideae which appears not to nodulate is the Dipterygeae, although the monogeneric Euchresteae has not been examined. A number of genera in the Swartzieae do not nodulate. Taking tile family as a whole, nodulation appears to be very uniform - certain sections nodulate, others do not.