Chitinase and peroxidase activity in different stages of eucalypt leaves after inoculation with Puccinia psidii and acibenzolar-S-metil

Chitinase and peroxidase activity in different stages of eucalypt leaves after inoculation with Puccinia psidii and acibenzolar-S-metil To elucidate some biochemical processes during infection in the pathosystem Puccinia psidii x eucalyptus, the defense metabolism in different-stage leaves was compared between rust-resistant and susceptible clones, respectively. In addition, chitinase and peroxidase activities were assayed. Each treatment consisted of 4 replicates, in a completely randomized design: 2 clones, inoculated and not inoculated with P. psidii; sprayed with acibenzolar-S-methyl (ASM) and distilled water; and represented by the 1(st) leaf pair (size equivalent to 1/5 total leaf development), 2(nd) pair (2/5 total development), and 4(th) pair (4/5 total leaf length). Leaves were harvested in 4 periods: 0, 24, 72 and 96 hours after inoculation. Results indicated that ASM treatment or P. psidii action led to higher chitinase and peroxidase activity level but did not alter the expression of these activities in developed leaves (4(th) pair) during the experiment. Alterations in enzyme levels after inoculation were only observed in developing leaves (1(st) and 2(nd) pairs), which suggests that the response to infection was concomitant to chitinase and peroxidase synthesis. The highest increases in enzymatic activities were observed in resistant clones at 72 hours after inoculation and in susceptible ones previously treated with ASM and later inoculated with the pathogen.

Effect of acibenzolar-S-methyl and Saccharomyces cerevisiae on the activation of Eucalyptus defences against rust

Tree defence mechanisms against the fungus Puccinia psidii were examined by comparing the activities of defence-related enzymes (chitinase, peroxidase and phenylalanine ammonia-lyase) of two Eucalyptus grandis x E. urophylla (urograndis) hybrids, previously classified as either susceptible to rust (VR hybrid) or moderately resistant to rust (C0 hybrid). Furthermore, the potential of disease control by artificial activation of host defences using either acibenzolar-S-methyl (ASM) or Saccharomyces cerevisiae extract was also investigated. Greenhouse inoculation trials revealed that the C0 hybrid had lower disease severity than the VR hybrid but following foliar applications of either ASM or S. cerevisiae extract treatment, disease severity (evaluated at 15 days after inoculation) was reduced in both hybrids. This enhanced resistance was associated with the induction of a hypersensitive reaction which appeared to be effective in controlling rust in both clones. The activity of all enzymes differed between clones and inducer treatment. The role of the defence-related enzymes in imparting resistance to eucalypt hybrids against rust is discussed.

Ockham's Razor: The Discovery of Neptune

The discovery of Neptune in September 1846 is a good example of scientific rationality but it has proven to be surprisingly difficult to explain how this is so from the perspective of Karl Popper, Thomas Kuhn and several other commentators who have been influenced by these thinkers. I try briefly to explain how to avoid these difficulties and understand the achievement of the astronomers who predicted the location of the new planet, Urbain J. J. Leverrier and John Couch Adams.

Popper and his Commentators on the Discovery of Neptune: a close shave for the Law of Gravitation?

Knowledge of residual perturbations in the orbit of Uranus in the early 1840s did not lead to the refutation of Newton's law of gravitation but instead to the discovery of Neptune in 1846. Karl Popper asserts that this case is atypical of science and that the law of gravitation was at least prima facie falsified by these perturbations. I argue that these assertions are the product of a false, a priori methodological position I call, 'Weak Popperian Falsificationism' (WPF). Further, on the evidence the law was not prima facie false and was not generally considered so by astronomers at the time. Many of Popper's commentators (Kuhn, Lakatos, Feyerabend and others) presuppose WPF and their views on this case and its implications for scientific rationality and method suffer from this same defect.

Sequence analysis, chromosomal distribution and long-range organization show that rapid turnover of new and old pBuM satellite DNA repeats leads to different patterns of variation in seven species of the Drosophila buzzatii cluster

We aimed to study patterns of variation and factors influencing the evolutionary dynamics of a satellite DNA, pBuM, in all seven Drosophila species from the buzzatii cluster (repleta group). We analyzed 117 alpha pBuM-1 (monomer length 190 bp) and 119 composite alpha/beta (370 bp) pBuM-2 repeats and determined the chromosome location and long-range organization on DNA fibers of major sequence variants. Such combined methodologies in the study of satDNAs have been used in very few organisms. In most species, concerted evolution is linked to high copy number of pBuM repeats. Species presenting low-abundance and scattered distributed pBuM repeats did not undergo concerted evolution and maintained part of the ancestral inter-repeat variability. The alpha and alpha/beta repeats colocalized in heterochromatic regions and were distributed on multiple chromosomes, with notable differences between species. High-resolution FISH revealed array sizes of a few kilobases to over 0.7 Mb and mutual arrangements of alpha and alpha/beta repeats along the same DNA fibers, but with considerable changes in the amount of each variant across species. From sequence, chromosomal and phylogenetic data, we could infer that homogenization and amplification events involved both new and ancestral pBuM variants. Altogether, the data on the structure and organization of the pBuM satDNA give insights into genome evolution including mechanisms that contribute to concerted evolution and diversification.

Numerical simulation of double-diffusion driven convective flow and rock alteration in three-dimensional fluid-saturated geological fault zones

Numerical methods are used to simulate the double-diffusion driven convective pore-fluid flow and rock alteration in three-dimensional fluid-saturated geological fault zones. The double diffusion is caused by a combination of both the positive upward temperature gradient and the positive downward salinity concentration gradient within a three-dimensional fluid-saturated geological fault zone, which is assumed to be more permeable than its surrounding rocks. In order to ensure the physical meaningfulness of the obtained numerical solutions, the numerical method used in this study is validated by a benchmark problem, for which the analytical solution to the critical Rayleigh number of the system is available. The theoretical value of the critical Rayleigh number of a three-dimensional fluid-saturated geological fault zone system can be used to judge whether or not the double-diffusion driven convective pore-fluid flow can take place within the system. After the possibility of triggering the double-diffusion driven convective pore-fluid flow is theoretically validated for the numerical model of a three-dimensional fluid-saturated geological fault zone system, the corresponding numerical solutions for the convective flow and temperature are directly coupled with a geochemical system. Through the numerical simulation of the coupled system between the convective fluid flow, heat transfer, mass transport and chemical reactions, we have investigated the effect of the double-diffusion driven convective pore-fluid flow on the rock alteration, which is the direct consequence of mineral redistribution due to its dissolution, transportation and precipitation, within the three-dimensional fluid-saturated geological fault zone system. (c) 2005 Elsevier B.V. All rights reserved.

Carbene and nitrene rearrangements: A theoretical study of cyclic allenes and carbenes, carbodiimides, and azirines

B3LYP/6-31G(d) calculations of structures, energies, and infrared spectra of several rearrangement products of (hetero)aromatic nitrenes and carbenes are reported. 3-Isoquinolylnitrene 36 ring closes to the azirine 37 prior to ring expansion to the potentially stable but unobserved seven-membered-ring carbodiimide 38 and diazacycloheptatrienylidene C-s-39S. A new, stable cycloheptatrienylidene, C-s-19S, is located on the naphthylcarbene energy surface. 4-Quinolylnitrene undergoes reaction via the azirine 50 in solution, but ring expansion to the stable seven-membered-ring ketenimine 47 under Ar matrix photolysis conditions. There is excellent agreement between calculated infrared spectra of 1,5-diazacyclohepta-1,2,4,6-tetraene 54 (obtained by photolysis of 4-pyridyl azide), 1-azacyclohepta-1,2,4,6-tetraene 5, 1-azacyclohepta-1,3,5,6-tetraene 55, and 1-azacyclohepta-1,3,4,6-tetraene 56 and the available experimental data.

2-cyano(2-pyridyl)ketene

Flash vacuum thermolysis of quinolizinones is a new way of generating ketenes. The title ketene is obtained from 1-cyano-2-hydroxyquinolizine-4-one and characterized by its Ar matrix infrared spectrum. (C) Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany 2002.

Quinolizine-2,4-diones by reversible dimerisation 2-pyridylketenes

Quinolizine-2,4-diones 11 are obtained by ash vacuum thermolysis (FVT) of 3-acyl-1,2,3-triazolo[1,5-a]pyridines 7. The reaction takes place via methyl- and phenyl(2-pyridyl)ketenes 10, which are directly observable by infrared spectroscopy in low temperature matrices. FVT of 11 regenerates the ketenes 10.

History and nomenclature of the theropod dinosaur tracks Bueckeburgichnus and Megalosauripus

The most recent account of Bueckeburgichnus maximus Kuhn 1958, a distinctive theropod dinosaur track from the Lower Cretaceous of Germany, is shown to be based on a referred specimen mistakenly identified as the holotype and the correct name of this taxon is deemed to be Megalosauripus maximus (Kuhn 1958). This minor revision has important consequences for nomenclature of the many European, Asian, North American and Australian dinosaur tracks attributed to megalosaurian theropods. Many of those tracks were named Megalosauripus, but that name has a confusing multiplicity of meanings and it should be restricted to the highly characteristic dinosaur track formerly identified as Bueckeburgichnus. Other tracks named "Megalosauripus”; (in its several other senses) will require new nomenclature, despite their extensive and repeated revision since 1996. It is recommended that future revision should adopt conventions of the International Code of Zoological Nomenclature. Although previous revisions expressed an intention to adhere to those conventions, these were not put into practice, with the unfortunate result of multiplying the problems that surround the nomenclature of megalosaur tracks. Introduction of the name Megalosauripus maximus (Kuhn 1958) eliminates those burgeoning problems and permits the introduction of new and objective nomenclature for presumed megalosaur tracks.

A economia da informação : rumo a um programa de pesquisa alternativo

Este trabalho tem por objetivo discutir o surgimento de um programa de pesquisa na Ciência Econômica, no que concerne a análise das assimetrias de informação, as diferenças epistemológicas e as implicações em termos de equilíbrio ótimo de Pareto, em contraponto à abordagem neoclássica standard. Em busca de tal objetivo, foi necessário destacar o método de ambos os paradigmas; todavia, era igualmente necessário discutir a filosofia/epistemologia da ciência envolvida e que serviria de base para uma abordagem relacionada a mudanças paradigmáticas na ciência. No capítulo 1, discutimos a epistemologia da ciência, a partir de três autores: Popper, Kuhn e Lakatos. Definimos o conjunto de hipóteses que podem ser associadas ao método empregado pela Escola Neoclássica, a partir da filosofia da ciência proposta por Lakatos. Em seguida, no capítulo 2, fizemos uma longa exposição do método neoclássico, definindo os axiomas inerentes às preferências bem-comportadas, apresentando algebricamente o equilíbrio geral walrasiano, exemplificando o relaxamento de hipóteses auxiliares do modelo neoclássico a partir de Friedman e, por fim, aplicando o instrumental neoclássico ao relaxamento da hipótese auxiliar de perfeição da informação, a partir do modelo desenvolvido por Grossman & Stiglitz (1976), bem como da expansão matemática desenvolvida pelo presente trabalho. Finalmente, encerramos a presente dissertação com o capítulo 3, no qual, basicamente, expomos as principais contribuições de autores como Stiglitz, Akerlof e Arrow, no que concerne a mercados permeados por informações assimétricas e comportamentos oportunistas. Procuramos mostrar as consequências para o próprio mercado, chegando a resultados em que o mesmo era extinto. Apresentamos a segunda parte do modelo de Grossman & Stiglitz, enfatizando a natureza imperfeita do sistema de preços, sua incapacidade de transmitir todas as informações sobre os bens ao conjunto dos agentes, e, por fim, discutimos tópicos variados ligados à Economia da Informação.

Sintomas psicológicos concomitantes à queixa de vertigem em 846 prontuários de pacientes otoneurológicos do Ambulatório de Otoneurologia da Universidade Federal de São Paulo - Escola Paulista de Medicina

OBJETIVO: Verificar os sintomas psicológicos mais freqüentemente associados à queixa de vertigem de acordo com os registros de prontuários de pacientes otoneurológicos. FORMA DE ESTUDO: Clínico retrospectivo. MÉTODO: Foram quantificados os dados relativos a sexo, idade e sintomas psicológicos, de acordo com os registros de 846 prontuários de triagem de pacientes otoneurológicos com queixa de vertigem, atendidos pelo Setor de Triagem do Ambulatório de Otoneurologia e Otoneuropsicologia da Universidade Federal de São Paulo - Escola Paulista de Medicina, nos períodos de 1999 a 2001. RESULTADOS: A concomitância de sintomas psicológicos à queixa de vertigem foi verificada em 477 (56,38%), de um total de 846 prontuários. Os sintomas psicológicos associados à queixa de vertigem foram a angústia (47,38%), a ansiedade (19,71%), o medo (13,42%) a depressão (12,58%) e os distúrbios de memória (6,92%). CONCLUSÃO: A angústia foi o sintoma psicológico concomitante à queixa de vertigem de maior prevalência (47,38%).