Impacto do aumento da concentração de CO2 atmosférico sobre a ferrugem asiática e o desenvolvimento de plantas de soja.

Resumo: A concentração de dióxido de carbono (CO2) na atmosfera tem aumentado significativamente nas últimas décadas e as previsões indicam que os valores atuais podem dobrar até o final do século. O presente estudo teve por objetivo avaliar o efeito do aumento da concentração de CO2 atmosférico na severidade da ferrugem asiática da soja, causada por Phakopsora pachyrhizi, e no desenvolvimento da planta. O experimento foi conduzido em estufas de topo aberto (OTC), com e sem injeção de CO2, e teve como testemunha o tratamento sem estufa, correspondendo, em média, às concentrações de 664 ppm, 463 ppm e 448 ppm, respectivamente. A alta concentração de CO2 reduziu a severidade da doença, mas não alterou a quantidade de uredósporos produzidos; estimulou o crescimento e a nodulação das plantas; no entanto, a massa seca das plantas não diferiu significativamente entre os tratamentos. Os resultados indicam que o aumento da concentração de CO2 atmosférico resultará em uma tendência de redução da importância da doença. Abstract: The atmospheric carbon dioxide (CO2) concentration is rising significantly in recent decades and projections indicate that current values may double by the end of the century. This study aimed to evaluate the effect of increased atmospheric CO2 concentration on the severity of Asian soybean rust caused by Phakopsora pachyrhizi, and plant development. The experiment was conducted in open-top chambers (OTC) with and without CO2 injection and a control treatment without OTC, corresponding to concentrations of 664 ppm, 463 ppm and 448 ppm, on average, respectively. The high concentration of CO2 reduced the severity of the disease, but not the amount of uredospores produced; stimulated the growth and nodulation of the plants; however, the plants dry weight did not differ significantly. The results indicate that the increase in CO2 atmospheric concentration can reduce the importance of the disease.bitstream/item/34450/1/boletim-57.pd

Efeito do aumento da concentração de CO2 atmosférico sobre a comunidade microbiana do filoplano da soja em estufa de topo aberto.

A concentração de CO2 atmosférico está se elevando nas últimas décadas como conseqüência das ações antrópicas. Essa alteração, além de intensificar o fenômeno do efeito estufa, pode afetar diretamente o manejo de algumas plantas e microrganismos de interesse agrícola. O objetivo desse estudo foi avaliar a comunidade microbiana de Bacillus spp., Pseudomonas spp., Trichoderma spp. e leveduras presentes no filoplano da soja cultivada em estufa de topo aberto com elevada concentração de CO2 atmosférico. O delineamento experimental adotado foi o de blocos ao acaso, constituído por três tratamentos: testemunha sem estufa; estufa com atmosfera ambiente sem injeção de CO2; estufa com injeção de CO2 até atingir a concentração de 550 ?L.L-1, com três repetições. Dois ensaios foram realizados, sendo o primeiro em março (Ensaio 1) e o segundo, em agosto de 2007 (Ensaio 2). O isolamento dos microrganismos do filoplano foi realizado a partir de plantas de soja (cultivar FT-Estrela) no estádio de desenvolvimento V4 (quarto nó e terceiro trifólio aberto), 30 dias após a emergência das plântulas. Fez-se a coleta do segundo trifólio de três plantas, escolhidas aleatoriamente dentro de cada parcela. Em seguida, as folhas foram colocadas em frascos contendo solução tampão fosfato esterilizado e submetidas a tratamento em ultra-som por 10 minutos. Para cada suspensão, foram feitas três diluições (10-1, 10-2 e 10-3), com três repetições. Alíquotas das suspensões obtidas foram transferidas para placas de Petri contendo meios de cultura específicos: King B para seleção de Pseudomonas spp.; extrato de malte, para leveduras; e meio de Martin para Trichoderma spp. Para o isolamento seletivo de Bacillus spp., a primeira diluição (10-1) foi submetida a 80ºC por 10 minutos, em banho-maria, antes da transferência para meio de BDA. A avaliação dos microrganismos foi realizada pela contagem das unidades formadoras de colônia por área foliar (ufc/cm2). No Ensaio 1, não houve efeito do aumento da concentração de CO2 sobre a comunidade de Bacillus spp., porém houve redução de Pseudomonas spp.. No Ensaio 2, o tratamento aumentou as comunidades de Bacillus spp. e Pseudomonas spp. O enriquecimento da atmosfera com CO2 não mostrou efeito sobre Trichoderma spp. e leveduras. Os resultados demonstram que o aumento da concentração do gás pode ter efeito sobre a microbiota do filoplano, especialmente na comunidade de bactérias

DNA-Cytophotometry of Lymph Node Touch Imprints in Cutaneous T-Cell Lymphoma

Scanning DNA-cytophotometry was performed on touch imprints of 26 lymph nodes (LN) obtained from 25 patients with cutaneous T-cell lymphoma (CTCL), stained by the Feulgen technique, and interpreted without knowledge of histopathologic diagnosis. Four patterns of DNA distribution were identified, but only histograms that demonstrated cells containing nuclei with more than 4C DNA content (hypertetraploidy) reliably distinguished LN involved with CTCL from LN with reactive changes; for example, dermatopathic lymphadenitis. An abnormal DNA histogram with evidence of hypertetraploidy was demonstrated in 9 of 12 LN showing histopathologic evidence of involvement compared with no abnormal histograms in 14 LN without histopathologic involvement. One LN that was diffusely involved with CTCL had a DNA distribution characteristic of a relatively high level of cell proliferation, but without definite hypertetraploidy. Cytogenetic studies on the blood of this patient, who had Sézary syndrome, demonstrated a clone of lymphocytes with a pseudodiploid karyotype without a related polyploid subline. The remaining two histopathologically involved LN had normal DNA histograms; these LN were only focally involved with CTCL. These observations indicate that DNA-cytophotometry correlates well with the histopathologic findings in LN diffusely involved with CTCL, but may be normal in LN with focal involvement or in those that contain cytogenetically abnormal cells with a near-dip- kid DNA content

Effects of Nutrient Management Scenarios on Marine Eutrophication Indicators: A Pan-European, Multi-Model Assessment in Support of the Marine Strategy Framework Directive

A novel pan-European marine model ensemble was established, covering nearly all seas under the regulation of the Marine Strategy Framework Directive (MSFD), with the aim of providing a consistent assessment of the potential impacts of riverine nutrient reduction scenarios on marine eutrophication indicators. For each sea region, up to five coupled biogeochemical models from institutes all over Europe were brought together for the first time. All model systems followed a harmonised scenario approach and ran two simulations, which varied only in the riverine nutrient inputs. The load reductions were evaluated with the catchment model GREEN and represented the impacts due to improved management of agriculture and wastewater treatment in all European river systems. The model ensemble, comprising 15 members, was used to assess changes to the core eutrophication indicators as defined within MSFD Descriptor 5. In nearly all marine regions, riverine load reductions led to reduced nutrient concentrations in the marine environment. However, regionally the nutrient input reductions led to an increase in the non-limiting nutrient in the water, especially in the case of phosphate concentrations in the Black Sea. Further core eutrophication indicators, such as chlorophyll-a, bottom oxygen and the Trophic Index TRIX, improved nearly everywhere, but the changes were less pronounced than for the inorganic nutrients. The model ensemble displayed strong consistency and robustness, as most if not all models indicated improvements in the same areas. There were substantial differences between the individual seas in the speed of response to the reduced nutrient loads. In the North Sea ensemble, a stable plateau was reached after only three years, while the simulation period of eight years was too short to obtain steady model results in the Baltic Sea. The ensemble exercise confirmed the importance of improved management of agriculture and wastewater treatments in the river catchments to reduce marine eutrophication. Several shortcomings were identified, the outcome of different approaches to compute the mean change was estimated and potential improvements are discussed to enhance policy support. Applying a model ensemble enabled us to obtain highly robust and consistent model results, substantially decreasing uncertainties in the scenario outcom

Comparing benthic biogeochemistry at a sandy and a muddy site in the Celtic Sea using a model and observations

Results from a 1D setup of the European Regional Seas Ecosystem Model (ERSEM) biogeochemical model were compared with new observations collected under the UK Shelf Seas Biogeochemistry (SSB) programme to assess model performance and clarify elements of shelf-sea benthic biogeochemistry and carbon cycling. Observations from two contrasting sites (muddy and sandy) in the Celtic Sea in otherwise comparable hydrographic conditions were considered, with the focus on the benthic system. A standard model parameterisation with site-specific light and nutrient adjustments was used, along with modifications to the within-seabed diffusivity to accommodate the modelling of permeable (sandy) sediments. Differences between modelled and observed quantities of organic carbon in the bed were interpreted to suggest that a large part (>90%) of the observed benthic organic carbon is biologically relatively inactive. Evidence on the rate at which this inactive fraction is produced will constitute important information to quantify offshore carbon sequestration. Total oxygen uptake and oxic layer depths were within the range of the measured values. Modelled depth average pore water concentrations of ammonium, phosphate and silicate were typically 5–20% of observed values at the muddy site due to an underestimate of concentrations associated with the deeper sediment layers. Model agreement for these nutrients was better at the sandy site, which had lower pore water concentrations, especially deeper in the sediment. Comparison of pore water nitrate with observations had added uncertainty, as the results from process studies at the sites indicated the dominance of the anammox pathway for nitrogen removal; a pathway that is not included in the model. Macrofaunal biomasses were overestimated, although a model run with increased macrofaunal background mortality rates decreased macrofaunal biomass and improved agreement with observations. The decrease in macrofaunal biomass was compensated by an increase in meiofaunal biomass such that total oxygen demand remained within the observed range. The permeable sediment modification reproduced some of the observed behaviour of oxygen penetration depth at the sandy site. It is suggested that future development in ERSEM benthic modelling should focus on: (1) mixing and degradation rates of benthic organic matter, (2) validation of benthic faunal biomass against large scale spatial datasets, (3) incorporation of anammox in the benthic nitrogen cycle, and (4) further developments to represent permeable sediment processes

Photocarcinogenesis in human adult skin grafts.

It has been demonstrated previously that the exposure to 7,12-dimethyl[a]benzanthracene (DMBA) and UVB radiation leads to the development of epidermal cysts, squamous cell carcinomas (SCC), melanocytic hyperplasia and melanoma in human foreskins from newborns grafted to immunodeficient mice. Improved techniques in grafting full-thickness skin from adults have enabled us to study photocarcinogenesis in human skin from different body sites and from older donors. One hundred and fifty-five normal white skin specimens from the trunk and face of 53 adult individuals were grafted onto severe combined immunodeficient (SCID) and recombinase activating gene-1 (Rag-1) knockout mice and irradiated two to three times weekly with 40 mJ/cm(2) UVB or solar-simulated UV (SSUV) over a period of up to 10 months with or without one prior topical application of DMBA. Over an observation period of 2-22 months, histopathological and immunohistochemical analyses of 134 specimens revealed actinic keratoses in 30% of the DMBA- + UV-treated grafts, in 18% of the grafts exposed to SSUV only, and in 10% of the grafts exposed to UVB only. Actinic keratoses were absent in grafts treated with DMBA only. One SCC was found in an abdominal skin graft 3 months after exposure to DMBA followed by UVB. Point mutations in codon 61 of the human Ha-ras gene were detected in the SCC, five of six analyzed actinic keratoses and in non-lesional epidermis of DMBA- and UVB-treated grafts, indicating that DMBA as well as UVB alone can induce these mutations in human skin. In contrast to the previous experience with neonatal foreskin grafts, melanocytic lesions were not found except for mild hyperplasia in few cases. The data suggest that melanocytes from young individuals are more susceptible to the transforming effects of genotoxic agents than melanocytes from adults