Avaliação do possível impacto de milho geneticamente modificado na ciclagem do nitrogênio em solo de Cerrado.

Fertbio 2012

Random amplified polymorphic DNA analysis of effective Rhizobium sp. associated with beans cultivated in Brazilian cerrado soils.

Efficient bean nodulating Rhizobium strains, isolated from different Brazilian cerrado soils, were characterized by RAPD. This study showed great genetic heterogeneity among R. tropici and R. leguminosarum bv. phaseoli strains and allowed the constitution of genetic clusters, besides indicating the most suitable primers for this characterization. The groups of genetically distinct strains can be used in competitiveness studies to select appropriate Rhizobium strains for bean inoculation in cerrado soils

Systems genetics approaches for understanding complex traits with relevance for human disease.

peer reviewedQuantitative traits are often complex because of the contribution of many loci, with further complexity added by environmental factors. In medical research, systems genetics is a powerful approach for the study of complex traits, as it integrates intermediate phenotypes, such as RNA, protein, and metabolite levels, to understand molecular and physiological phenotypes linking discrete DNA sequence variation to complex clinical and physiological traits. The primary purpose of this review is to describe some of the resources and tools of systems genetics in humans and rodent models, so that researchers in many areas of biology and medicine can make use of the data

Ab-initio structural, elastic, and vibrational properties of carbon nanotubes

A study based on ab initio calculations is presented on the estructural, elastic, and vibrational properties of single-wall carbon nanotubes with different radii and chiralities. We use SIESTA, an implementation of pseudopotential-density-functional theory which allows calculations on systems with a large number of atoms per cell. Different quantities like bond distances, Young moduli, Poisson ratio and the frequencies of different phonon branches are monitored versus tube radius. The validity of expectations based on graphite is explored down to small radii, where some deviations appear related to the curvature effects. For the phonon spectra, the results are compared with the predictions of the simple zone-folding approximation. Except for the known defficiencies of this approximation in the low-frequency vibrational regions, it offers quite accurate results, even for relatively small radii.Comment: 13 pages, 7 figures, submitted to Phys. Rev. B (11 Nov. 98

Modern optical astronomy: technology and impact of interferometry

The present `state of the art' and the path to future progress in high spatial resolution imaging interferometry is reviewed. The review begins with a treatment of the fundamentals of stellar optical interferometry, the origin, properties, optical effects of turbulence in the Earth's atmosphere, the passive methods that are applied on a single telescope to overcome atmospheric image degradation such as speckle interferometry, and various other techniques. These topics include differential speckle interferometry, speckle spectroscopy and polarimetry, phase diversity, wavefront shearing interferometry, phase-closure methods, dark speckle imaging, as well as the limitations imposed by the detectors on the performance of speckle imaging. A brief account is given of the technological innovation of adaptive-optics (AO) to compensate such atmospheric effects on the image in real time. A major advancement involves the transition from single-aperture to the dilute-aperture interferometry using multiple telescopes. Therefore, the review deals with recent developments involving ground-based, and space-based optical arrays. Emphasis is placed on the problems specific to delay-lines, beam recombination, polarization, dispersion, fringe-tracking, bootstrapping, coherencing and cophasing, and recovery of the visibility functions. The role of AO in enhancing visibilities is also discussed. The applications of interferometry, such as imaging, astrometry, and nulling are described. The mathematical intricacies of the various `post-detection' image-processing techniques are examined critically. The review concludes with a discussion of the astrophysical importance and the perspectives of interferometry.Comment: 65 pages LaTeX file including 23 figures. Reviews of Modern Physics, 2002, to appear in April issu

Atividade microbiana em solos de várzea e Cerrado cultivados com milho transgênico expressando os genes Cry1Ab e Cry1F de Bacillus thuringiensis.

Em razão das vantagens agronômicas e dos benefícios econômicos, a área de cultivo de culturas geneticamente modificadas (GM) tem aumentado nos últimos anos. Embora vários estudos tenham sido conduzidos para determinar os possíveis efeitos da tecnologia Bt nas comunidades microbianas do solo, os resultados não fornecem respostas conclusivas. Dessa forma, este trabalho teve como objetivo avaliar a atividade microbiana em solos rizosférico e não rizosférico de milho transgênico e não transgênicos cultivados em Várzea e Cerrado. Testaram-se dois eventos transgênicos independentes expressando as proteínas Cry1Ab (30F35Y) ou Cry1F (30F35H) e o híbrido original (30F35), não transformado, em delineamento experimental de blocos ao acaso com três repetições. Para determinação da atividade das enzimas urease, arginase, fosfatases ácida/alcalina e diversidade metabólica via sistema Biolog, as amostras de solo foram coletadas no estádio de florescimentos das plantas. Exceto para a enzima fosfatase alcalina, observou-se maior atividade enzimática nas comunidades microbianas de solos rizosféricos e em solos do Cerrado. Não foram observadas alterações significativas na atividade microbiana entre os genótipos de milho com e sem a tecnologia Bt, independentemente do tipo de solo.bitstream/item/172367/1/bol-159.pd

Inferring Geographic Coordinates of Origin for Europeans Using Small Panels of Ancestry Informative Markers

Recent large-scale studies of European populations have demonstrated the existence of population genetic structure within Europe and the potential to accurately infer individual ancestry when information from hundreds of thousands of genetic markers is used. In fact, when genomewide genetic variation of European populations is projected down to a two-dimensional Principal Components Analysis plot, a surprising correlation with actual geographic coordinates of self-reported ancestry has been reported. This substructure can hamper the search of susceptibility genes for common complex disorders leading to spurious correlations. The identification of genetic markers that can correct for population stratification becomes therefore of paramount importance. Analyzing 1,200 individuals from 11 populations genotyped for more than 500,000 SNPs (Population Reference Sample), we present a systematic exploration of the extent to which geographic coordinates of origin within Europe can be predicted, with small panels of SNPs. Markers are selected to correlate with the top principal components of the dataset, as we have previously demonstrated. Performing thorough cross-validation experiments we show that it is indeed possible to predict individual ancestry within Europe down to a few hundred kilometers from actual individual origin, using information from carefully selected panels of 500 or 1,000 SNPs. Furthermore, we show that these panels can be used to correctly assign the HapMap Phase 3 European populations to their geographic origin. The SNPs that we propose can prove extremely useful in a variety of different settings, such as stratification correction or genetic ancestry testing, and the study of the history of European populations

Genetic mapping of microbial and host traits reveals production of immunomodulatory lipids by Akkermansia muciniphila in the murine gut.

The molecular bases of how host genetic variation impacts the gut microbiome remain largely unknown. Here we used a genetically diverse mouse population and applied systems genetics strategies to identify interactions between host and microbe phenotypes including microbial functions, using faecal metagenomics, small intestinal transcripts and caecal lipids that influence microbe-host dynamics. Quantitative trait locus (QTL) mapping identified murine genomic regions associated with variations in bacterial taxa; bacterial functions including motility, sporulation and lipopolysaccharide production and levels of bacterial- and host-derived lipids. We found overlapping QTL for the abundance of Akkermansia muciniphila and caecal levels of ornithine lipids. Follow-up in vitro and in vivo studies revealed that A. muciniphila is a major source of these lipids in the gut, provided evidence that ornithine lipids have immunomodulatory effects and identified intestinal transcripts co-regulated with these traits including Atf3, which encodes for a transcription factor that plays vital roles in modulating metabolism and immunity. Collectively, these results suggest that ornithine lipids are potentially important for A. muciniphila-host interactions and support the role of host genetics as a determinant of responses to gut microbes

Professional development in teaching and learning for early career academic geographers: Contexts, practices and tensions

This is an Accepted Manuscript of an article published by Taylor & Francis in Journal of Geography in Higher Education on 16th May 2011, available online: doi: 10.1080/03098265.2011.563380This paper provides a review of the practices and tensions informing approaches to professional development for early career academic geographers who are teaching in higher education. We offer examples from Britain, Canada, Nigeria and the USA. The tensions include: institutional and departmental cultures; models that offer generic and discipline-specific approaches; the credibility of alternative settings for professional development in teaching and learning; the valuing of professional development and of teaching in academic systems of reward and recognition; and the challenges of balancing professional and personal life. We summarize concepts of good practice and suggest opportunities for future research