Insufficient uracil supply in fully aerobic chemostat cultures of Saccharomyces cerevisiae leads to respiro-fermentative metabolism and double nutrient-limitation

A combination of chemostat cultivation and a defined medium was used to demonstrate that uracil limitation leads to a drastic alteration in the physiology of auxotrophic cells of Saccharomyces cerevisiae. Under this condition, the carbon source is dissimilated mainly to ethanol and acetate, even in fully aerobic cultures grown at 0.1 h(-1), which is far below the critical dilution rate. Differently from nitrogen-, sulphur-, or phosphate-limited cultures, uracil limitation leads to residual sugar (either glucose or sucrose) concentrations below 2 mM, which characterizes a situation of double-limitation: by the carbon source and by uracil. Furthermore, the specific rates of CO(2) production and O(2) consumption are increased when compared to the corresponding prototrophic strain. We conclude that when auxotrophic strains are to be used for quantitative physiological studies, special attention must be paid to the cultivation conditions, mainly regarding medium formulation, in order to avoid limitation of growth by the auxotrophic nutrient.

Seasonal and diurnal changes in photosynthetic limitation of young sweet orange trees

This study tests the hypothesis that potted sweet orange plants show a significant variation in photosynthesis over seasonal and diurnal cycles. even in well-hydrated conditions. This hypothesis was tested by measuring diurnal variations in leaf gas exchange, chlorophyll fluorescence, leaf water potential, and the responses of CO(2) assimilation to increasing air CO(2) concentrations in 1-year-old `Valencia` sweet orange scions grafted onto `Cleopatra` mandarin rootstocks during the winter and summer seasons in a subtropical climate. In addition, diurnal leaf gas exchange was evaluated under controlled conditions, with constant environmental conditions during both winter and summer. In relation to our hypothesis, a greater rate of photosynthesis is found during the summer compared to the winter. Reduced photosynthesis during winter was induced by cool night conditions, as the diurnal fluctuation of environmental conditions was not limiting. Low air and soil temperatures caused decreases in the stomatal conductance and in the rates of the biochemical reactions underlying photosynthesis (ribulose-1,5-bisphosphate (RuBP) carboxylation and RuBP regeneration) during the winter compared to the values obtained for those markers in the Summer. Citrus photosynthesis during the summer was riot impaired by biochemical or photochemical reactions. as CO(2) assimilation was only limited by stomatal conductance due to high leaf-to-air vapor pressure difference (VPD) during the afternoon. During the winter, the reduction in photosynthesis during the afternoon Was Caused by decreases in RuBP regeneration and stomatal conductance, which are both precipitated by low night temperature. (c) 2009 Elsevier B.V. All rights reserved.

Effects of bamboo stands on seed rain and seed limitation in a rainforest

Bamboos often negatively affect tree recruitment, survival, and growth, leading to arrested tree regeneration in forested habitats. Studies so far have focused on the effects of bamboos on the performance of seedlings and saplings, but the influence of bamboos on forest dynamics may start very early in the forest regeneration process by altering seed rain patterns. We tested the prediction that the density and composition of the seed rain are altered and seed limitation is higher in stands of Guadua tagoara (B or bamboo stands), a large-sized woody bamboo native from the Brazilian Atlantic Forest, compared to forest patches without bamboos (NB or non-bamboo stands). Forty 1 m(2) seed traps were set in B and NB stands, and the seed rain was monitored monthly for 1 year. The seed rain was not greatly altered by the presence of bamboos: rarefied seed species richness was higher for B stands, patterns of dominance and density of seeds were similar between stands, and differences in overall composition were slight. Seed limitation, however, was greater at B stands, likely as a resulted of reduced tree density. Despite Such reduced density, the presence of trees growing amidst and over the bamboos seems to play a key role in keeping the seeds falling in B stands because they serve as food sources for frugivores or simply as perches for them. The loss of such trees may lead to enhanced seed limitation, contributing ultimately to the self-perpetuating bamboo disturbance cycle. (C) 2008 Elsevier B,V. All rights reserved.

Divergence Involving Global Regulatory Gene Mutations in an Escherichia coli Population Evolving under Phosphate Limitation

Many of the important changes in evolution are regulatory in nature. Sequenced bacterial genomes point to flexibility in regulatory circuits but we do not know how regulation is remodeled in evolving bacteria. Here, we study the regulatory changes that emerge in populations evolving under controlled conditions during experimental evolution of Escherichia coli in a phosphate-limited chemostat culture. Genomes were sequenced from five clones with different combinations of phenotypic properties that coexisted in a population after 37 days. Each of the distinct isolates contained a different mutation in 1 of 3 highly pleiotropic regulatory genes (hfq, spoT, or rpoS). The mutations resulted in dissimilar proteomic changes, consistent with the documented effects of hfq, spoT, and rpoS mutations. The different mutations do share a common benefit, however, in that the mutations each redirect cellular resources away from stress responses that are redundant in a constant selection environment. The hfq mutation lowers several individual stress responses as well the small RNA-dependent activation of rpoS translation and hence general stress resistance. The spoT mutation reduces ppGpp levels, decreasing the stringent response as well as rpoS expression. The mutations in and upstream of rpoS resulted in partial or complete loss of general stress resistance. Our observations suggest that the degeneracy at the core of bacterial stress regulation provides alternative solutions to a common evolutionary challenge. These results can explain phenotypic divergence in a constant environment and also how evolutionary jumps and adaptive radiations involve altered gene regulation.

Limitation of double folding potentials to simulate the polarization in reactions involving halo nuclei

In this work, we investigate the limitation of the use of strength coefficients on double folding potentials to study the presence of the threshold anomaly in the elastic scattering of halo nuclei at near barrier energies. For this purpose, elastic angular distributions and reaction cross sections for the He-6 on Bi-209 are studied. (c) 2008 Elsevier B.V. All rights reserved.

Orbital abscess after facial trauma

This paper reports a rare case of acute severe orbital abscess manifested 2 days after a facial trauma without bone fracture in a 20-year-old Afro-American female. The symptoms worsened within the 24 h prior to hospital admission resulting in visual disturbances such as diplopia and photophobia. The clinical findings at the first consultation included fever, periorbital swelling and redness, ptosis, proptosis and limitation of ocular movements upwards, downwards, to the right and to the left. Computed tomography scan showed proptosis with considerable soft tissue swelling on the left side and no fracture was evidenced in the facial skeleton, including the zygomatic-orbital complex. After hospital admission and antibiotic therapy intravenously the patient was conducted to the operation room and submitted to incision and drainage under general anesthesia. The orbit was approached thorough both eyelids and the maxillary sinus was reached only through the Caldwell-Luc approach. The postoperative period was uneventful and the rapid improvement of symptoms was remarkable. Visual acuity and ocular motility returned to the normal ranges within 2 days after the surgical intervention. After 12 postoperative days, the patient presented with significative improvement in the ptosis and proptosis, and acceptable scars.

Evaluation of simulated bone lesion in the head of the mandible by using multislice computed tomography

Conventional radiography has shown limitation in acquiring image of the ATM region, thus, computed tomography (CT) scanning has been the best option to the present date for diagnosis, surgical planning and treatment of bone lesions, owing to its specific properties. OBJECTIVE: The aim of the study was to evaluate images of simulated bone lesions at the head of the mandible by multislice CT. MATERIAL AND METHODS: Spherical lesions were made with dental spherical drills (sizes 1, 3, and 6) and were evaluated by using multislice CT (64 rows), by two observers in two different occasions, deploying two protocols: axial, coronal, and sagittal images, and parasagittal images for pole visualization (anterior, lateral, posterior, medial and superior). Acquired images were then compared with those lesions in the dry mandible (gold standard) to evaluate the specificity and sensibility of both protocols. Statistical methods included: Kappa statistics, validity test and chi-square test. Results demonstrated the advantage of associating axial, coronal, and sagittal slices with parasagittal slices for lesion detection at the head of the mandible. RESULTS: There was no statistically significant difference between the types of protocols regarding a particular localization of lesions at the poles. CONCLUSIONS: Protocols for the assessment of the head of the mandible were established to improve the visualization of alterations of each of the poles of the mandible's head. The anterior and posterior poles were better visualized in lateral-medial planes while lateral, medial and superior poles were better visualized in the anterior-posterior plane.

O uso de sondagens dipolo-dipolo em estudos hidrogeológicos e de depósitos de resíduos

Ensaios de sondagem e caminhamento elétrico têm sido realizados globalmente na avaliação de uma grande variedade de problemas em exploração mineral e hidrogeologia, bem como na caracterização de locais com risco de contaminação. A despeito da utilidade de ensaios geoelétricos em estudos hidrogeológicos e na caracterização de depósitos de resíduos desativados, um problema na utilização de sondagens elétricas ocorre em conseqüência da falta de espaço para aquisição de dados nessas áreas. Em áreas urbanas, isto constitui uma limitação importante devido à existência de construções, o que muitas vezes interrompe o desenvolvimento de ensaios de campo com arranjos de comprimentos adequados. Embora investigações rasas tendam a ser eficazes em caracterização geoambiental, a estimativa de parâmetros-chave pode depender da investigação de porções mais profundas. Entretanto, uma profundidade de investigação ligeiramente maior é obtida pelo arranjo dipolo-dipolo em comparação aos arranjos Schlumberger e Wenner de mesmo comprimento. Essa característica do arranjo dipolo-dipolo pode ser observada em vários estudos, mas provavelmente devido à tradição e à relação sinal-ruído, a grande maioria das sondagens elétricas é feita com os arranjos Schlumberger e Wenner.O arranjo dipolo-dipolo é mais utilizado em ensaios 2D. Até onde se sabe, essa maior capacidade de investigação em profundidade do arranjo dipolo-dipolo 1D não foi explorada em estudos geoambientais e nem em estudos hidrogeológicos em áreas urbanas. Este trabalho apresenta resultados de ensaios de campo que ressaltam a utilidade de sondagens dipolo-dipolo na investigação de tais áreas.

Temporal variation of the phytoplankton community at short sampling intervals in the Mundaú reservoir, Northeastern Brazil

The aim of this study was to determine how abiotic factors drive the phytoplankton community in a water supply reservoir within short sampling intervals. Samples were collected at the subsurface (0.1 m) and bottom of limnetic (8 m) and littoral (2 m) zones in both the dry and rainy seasons. The following abiotic variables were analyzed: water temperature, dissolved oxygen, electrical conductivity, total dissolved solids, turbidity, pH, total nitrogen, nitrite, nitrate, total phosphorus, total dissolved phosphorus and orthophosphate. Phytoplankton biomass was determined from biovolume values. The role abiotic variables play in the dynamics of phytoplankton species was determined by means of Canonical Correspondence Analysis. Algae biomass ranged from 1.17×10(4) to 9.21×10(4) µg.L-1; cyanobacteria had biomass values ranging from 1.07×10(4) to 8.21×10(4) µg.L-1. High availability of phosphorous, nitrogen limitation, alkaline pH and thermal stability all favored cyanobacteria blooms, particularly during the dry season. Temperature, pH, total phosphorous and turbidity were key factors in characterizing the phytoplankton community between sampling times and stations. Of the species studied, Cylindrospermopsis raciborskii populations were dominant in the phytoplankton in both the dry and rainy seasons. We conclude that the phytoplankton was strongly influenced by abiotic variables, particularly in relation to seasonal distribution patterns.

Educação ambiental, sustentabilidade e ciência: o papel da mídia na difusão de conhecimentos científicos

São problemas de ordem ambiental: aquecimento global, mudanças climáticas, escassez de recursos naturais, resíduo. Em resposta, têm sido gerados novos saberes no campo da ciência, tecnologia e educação chamada ambiental de modo a se proporem alternativas para que o homem possa relacionar-se com o ambiente de maneira sustentável, e a mídia tem contribuído sobremaneira na veiculação desses conhecimentos. Na imprensa escrita, revistas e jornais têm criado seções, suplementos, cadernos tematizando educação e meio ambiente. Produzida pela revista Carta Capital, desde 2006, a revista Carta na Escola busca difundir "atualidades em sala de aula", e de setembro de 2007 a agosto de 2008 publicou a série "Sustentabilidade na Escola", com dez artigos relacionando sustentabilidade, ciência e educação. A partir do referencial teórico-metodológico da análise dialógica do discurso, este artigo analisa o discurso da sustentabilidade baseado na difusão de conhecimentos científicos, proposto nessa série, e sua limitação enquanto estratégia de educação ambiental.

Estratégias de pré-concentração em eletroforese capilar (CE): parte 1. Manipulação da velocidade eletroforética do analito

Capillary electrophoresis has become a well-established and routine-based separation technique. It is based on the differences between charged analyte mobility in aqueous or organic electrolytes. Its major limitation is the sensitivity due to small sample injection volumes and the narrow diameter of the capillaries, especially when UV detection is used. There are a number of ways to increase the concentration sensitivity. This report shows some on-line preconcentration strategies to perform it in free solution capillary electrophoresis that are based on manipulation of the analyte electrophoretic velocity during the sample introduction (stacking, field amplification and transient isotachophoresis).

Analysis of the prevalence of and factors associated with urinary incontinence among elderly people in the Municipality of São Paulo, Brazil: SABE Study (Health, Wellbeing and Aging)

To investigate the prevalence of urinary incontinence among elderly people living in São Paulo, Brazil and their associated risk factors. The Pan-American Health Organization and World Health Organization coordinated a multicenter study named Health, Wellbeing and Aging (SABE Study) in elderly people (over 60 years old) living in seven countries in Latin America and the Caribbean. In Brazil, the study was carried out in São Paulo in the year 2000. The total Brazilian sample included 2,143 people. The prevalence of self reported urinary incontinence was 11.8% among men and 26.2% for women. It was verified that among those reporting urinary incontinence, 37% also reported stroke and 34% depression. It was found that the greater the dependence that the elderly people presented, the greater the prevalence of urinary incontinence. The associated factors found were depression (odds ratio = 2.49), female (2.42), advanced age (2.35), important functional limitation (2.01). Urinary incontinence is a highly prevalent symptom among the elderly population of the municipality of São Paulo, especially among women. The adoption of preventive measures can reduce the negative effects of urinary incontinence.

Acessibilidade aos serviços de saúde por pessoas com deficiência

OBJETIVO: Analisar as dificuldades de acessibilidade aos serviços de saúde vividas por pessoas com deficiência. PROCEDIMENTOS METODOLÓGICOS: Estudo qualitativo realizado com pessoas que relataram ter algum tipo de deficiência (paralisia ou amputação de membros; baixa visão, cegueira unilateral ou total; baixa audição, surdez unilateral ou total). Foram entrevistados 25 indivíduos (14 mulheres) na cidade de São Paulo, SP, de junho a agosto de 2007, que responderam perguntas referentes a deslocamento e acessibilidade aos serviços de saúde. A metodologia utilizada para análise foi o discurso do sujeito coletivo e as análises foram conduzidas com recurso do programa Qualiquantisoft. ANÁLISE DOS RESULTADOS: A análise dos discursos sobre o deslocamento ao serviço de saúde mostrou diversidade quanto ao usuário ir ao serviço sozinho ou acompanhado, utilizar carro particular, transporte coletivo, ir a pé ou de ambulância e demandar tempo variado para chegar ao serviço. Com relação às dificuldades oferecidas de acessibilidade pelos serviços de saúde, houve relatos de demora no atendimento, problemas com estacionamento, falta de rampas, elevadores, cadeiras de rodas, sanitários adaptados e de médicos. CONCLUSÕES: As pessoas com algum tipo de deficiência fizeram uso de meios de transporte diversificados, necessitando de companhia em alguns casos. Problemas na acessibilidade dos serviços de saúde foram relatados pelos sujeitos com deficiências, contrariando o princípio da eqüidade, preceito do Sistema Único de Saúde.

Pós-alta em Hanseníase no Ceará: limitação da atividade funcional, consciência de risco e participação social

Caracterizar a limitação funcional, de atividade, consciência de risco, e restrição à participação social em pessoas atingidas pela hanseníase no pós-alta. Estudo seccional-descritivo com 69 residentes em Sobral, Ceará, com alta entre 2003 a 2005. Foram realizados exame físico dermato-neurológico, avaliação demográfica, de limitação funcional-atividade-consciência de risco e de restrição à participação social. Vinte (28,9%) apresentaram escores SALSA 19 e 20 e escore EHF zero. O maior escore EHF foi alcançado por dois participantes, com 25 e 28 na escala SALSA. Na escala de participação 37 (53,6%) não apresentaram restrição e tinham escore EHF zero. Dois (2,9%) com escore EHF zero tinham leve restrição e 1 (1,5%), grande restrição. Reafirma-se a potencialidade destas ferramentas para a atenção integral aos portadores.

Limitação de atividades e participação social em pacientes com diabetes

Objetivos: Avaliar a limitação de atividades e a participação social em indivíduos portadores de diabetes melito tipo 2. Métodos: Foram avaliados 79 pacientes, utilizando-se a escala SALSA (Screening of Activity Limitation and Safety Awareness - Triagem de Limitação de Atividade e Consciência de Risco), e a escala de Participação, que abrange oito das nove principais áreas da vida definidas na Classificação Internacional de Funcionalidade, Incapacidade e Saúde (CIF) da OMS. Resultados: A idade média dos participantes foi 61,6 ± 9,8 anos, sendo 55,7 por cento do sexo feminino, 68,4 por cento com companheiro(a), 32,9 por cento com renda até 3 salários mínimos e em 13,9 por cento o diabete influenciou na ocupação. O tempo médio de doença foi 10,3 ± 8,9 anos. Tratamento de 39,3 por cento dos participantes foi com insulina, 70,9 por cento com medicação oral, 51,9 por cento com dieta e 45,6 por cento com exercícios físicos. 48,1 por cento apresentavam alguma complicação da doença. A média de pontos SALSA foi 26,5 ± 11,6 e houve maior pontuação quando o tempo de doença foi superior a 10 anos. Com a evolução do diabetes, pode haver necessidade de insulinoterapia, aparecem as complicações, que podem interferir na ocupação. Estes fatores parecem contribuir para a limitação de atividade. A média de pontos na Escala de Participação foi 9,8±10,9, com maior pontuação quando os entrevistados consideraram sua saúde física alterada no último ano e faziam uso de insulina. Conclusões: A limitação de atividades no diabetes melito tipo 2 se associou ao tempo de doença, com possível contribuição de fatores que ocorrem com sua evolução. Auto-avaliação de saúde física alterada e insulinoterapia se associaram a restrição social