Browsing by Issue Date, starting with "1999-10"
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- Related RNAs in lepidopteran cells after in vitro infection with Hyposoter didymator virus define a new polydnavirus gene familyPublication . Volkoff, A. N.; Cerutti, P.; Rocher, J.; Ohresser, M. C. P.; Devauchelle, G.; Duonor-Cerutti, M.In the present study, we describe the isolation and the characterization of three different Hyposoter didymator virus (HdV) lepidopteran host-expressed genes, the products of which might interfere with the host physiology during parasitism. In this report, we study the expression of HdV genes in Sf9 cells infected with HdV since results indicate that the Sf9 model mimics to some extent the in vivo model and may be utilized to study expression of HdV genes in lepidopteran host cells. This system allowed us to isolate three HdV-specific cDNAs, termed M24, M27, and M40. cDNA nucleotide sequence analysis demonstrated significant regions of homology. The three cDNAs displayed repeated sequences arranged in tandem array that might have evolved through domain duplication. Similar to other previously described polydnavirus host-expressed genes, two intron positions have been found in the M24 leader region. The cDNAs corresponded to RNAs of 1.6, 1.6, and 2.3 kb that are also detected in parasitized Spodoptera littoralis larvae. They are encoded by different genes likely located on different HdV DNA molecules. Corresponding RNAs are detected early postinfection and remain detectable for at least 10 days postinfection. They encode secreted glycine- and proline-rich proteins. An antiserum raised against a baculovirus recombinant M24-encoded protein detected similar proteins in the culture medium of infected lepidopteran cells and in parasitized host hemolymph. We propose that the three cloned genes belong to an HdV gene family specifically expressed in parasitized lepidopteran hosts, (C) 1999 Academic Press.
- Concepção do reforço sísmico de edifícios de betão armadoPublication . Carreira, A. S.; Gomes, AugustoNeste artigo apresentam-se algumas técnicas de reforço e os critérios de avaliação da resistência para a acção dos sismos de edifícios existentes com estrutura em betão armado. Exemplifica-se a sua aplicação a um caso real, para o qual são ensaiadas várias soluções de reforço. Apresentam-se as principais conclusões em termos de melhoria do comportamento sísmico e refere-se, também, as estimativas de custos associadas às intervenções proposta.
- The use of sighting data to analyse Iberian lynx habitat and distributionPublication . Palma, Luis; Beja, Pedro; Rodrigues, Miguel1. Over a large part of its very restricted and fragmented range, Iberian lynx Lynx pardinus occur in remote mountainous country at low density, where the only information about the species comprises records of incidental sightings obtained by inquiry. In this study we developed an approach for quantifying lynx-habitat relationships and distribution patterns from sighting data, using records from western Algarve (Portugal) in 1990-95. 2. Habitat was described in terms of land cover, topography, human disturbance and rabbit abundance, in 25-km(2) cells surrounding lynx sightings and at random locations within the study area. 3. Lynx sightings were consistently associated with predictable habitat features. Sighting probabilities estimated from a logistic regression model increased with the abundance of rabbits and the proportion of land covered by tall Mediterranean maquis, and declined with road density and the amount of developed land. This model identified correctly 85.7% of lynx sightings; at the same time only 20.7% of the random locations were misclassified. 4. Indices of human presence were never associated positively with lynx sightings, suggesting that observation patterns were not influenced by the spatial distribution of potential observers. 5. Kriging was used to interpolate spatially between sighting probabilities derived from the logistic model in order to produce a map of sighting potential for the Iberian lynx in western Algarve. Jack-knife resampling assessed the accuracy of this map. Three well-defined areas of high sighting potential were identified, probably representing the lynx core areas in this region. 6. Our analysis of lynx sighting records suggests that these data may provide a first approximation to lynx habitat and distribution when further information is lacking. The application of this approach to other ran and reclusive species is discussed.
- Thermal inactivation of Alyciclobacillus acidoterrestris spores under different temperature, soluble solids and pH conditions for the design of fruit processesPublication . Silva, F. M.; Gibbs, P.; Silva, C. L. M.; Vieira, M. M. C.Alicyclobacillus acidoterrestris, a thermoacidophilic, non-pathogenic and spore-forming bacterium has been detected in several spoiled commercial pasteurised fruit juices. A. acidoterrestris spores, besides being resistant to the pasteurisation treatment conditions normally applied to acidic fruit products, can germinate and grow causing spoilage. Therefore, this microorganism was suggested as the target to be used in the design of adequate pasteurisation processes. The objectives of this work were to investigate the influence of temperature (T: 85–97°C), total soluble solids (SS: 5–60°Brix or % by weight) and pH (2.5–6.0) on D-values (decimal reduction time) of Alicyclobacillus acidoterrestris (type strain, NCIMB 13137) spores, and to fit a model using response surface methodology. A central composite face-centred experimental design was used, and the response, D-value determined in malt extract broth, ranged between 0.498±0.045 and 94.9±6.7 min. Within the factor ranges studied, temperature was the parameter that most affected the D-value. Following this was the SS and, lastly, the pH value. A linear decrease in D-value was observed with decreasing SS and pH, and a non-linear decrease in D-value was noticed with increasing temperature. A second order polynomial was successfully fitted to the data (R2=0.98). In general, D-values measured in real fruit systems, such as orange, apple and grape juices, blackcurrant concentrates, cupuaçu (exotic fruit) extract and orange juice drink, were higher than those predicted by the malt extract broth model. This result emphasises the importance of experimental validation of any model-derived process.
- A sofística e a educação ateniense no século V a.C.Publication . Nogueira, AdrianaA Sofística foi um movimento intelectual que se desenvolveu na Grécia, no Século V a.C., principalmente na cidade de Atenas. A escassez de documentos atestados como sendo dos próprios sofistas e a quantidade de testemunhos provenientes de contextos e origens diversos não permite uma evidente definição da actividade por eles praticada. Este artigo procurará abordar criticamente e esclarecer algumas pré-concepções sobre a Sofística.