Expressão de genes relacionados ao metabolismo de nitrogênio, fósforo de potássio em cafeeiros submetidos ao estresse biótico.

As plantas freqüentemente são ameaçadas por agentes externos que podem ser fatores bióticos e/ou abióticos. Para cada tipo de ameaça há um requintado tipo de resposta que caracteriza o processo de defesa. Dentre os processos de defesa enquadram-se a ativação ou repressão de genes relacionados como quitinases, glucanaes, lipoxigenases, transferases, entre outros. Quaisquer modificações bioquímicas que ocorram durante os ataques dos patógenos são indispensáveis para a compreensão deste mecanismo biológico. Correlacionar os mecanismos biológicos de regulação e transporte de íons com os diferentes períodos de infestação e infecção é uma dessas maneiras de elucidar os processos que ocorrem durante a infestação e infecção. Neste estudo foram analisados os perfis de expressão de 5 genes (HAK-5, KEA, PAP-1, PII, NTR) relacionados com o transporte e regulação de potássio e nitrogênio com diferentes estímulos bióticos e em diferentes etapas de cada um desses processos. Os resultados demonstraram que há padrões diferenciais de regulação entre as plantas suscetíveis e resistentes para todos os genes analisados. Estas análises preliminares indicam que a regulação da absorção e/ou transporte de nutrientes exerce um importante papel durante as respostas de defesa em cafeeiros contra o bicho mineiro

Gene expression during response to nutrient deficiency in leaf-miner resistant and susceptible genotypes.

Several physiologic factors affect the defense response of coffee trees to the leaf-miner (Leucoptera coffeella), including nutrient availability during plant growth. Resistant coffee plants may exhibit leaf-miner infection when field nutritional status is critical. Knowledge of how biological mechanisms associated with transport of macronutrients and defense to leaf-miner infection interact may provide insights to elucidate the resistance response. In this study, we investigated the expression profile of genes from potassium and nitrogen metabolism, oxidative stress and defense response, in coffee seedlings submitted to limiting nutritional conditions. Young plants from both resistant and susceptible genotypes were irrigated with solutions containing variable macronutrients (N+K+, N+K-, NK+, NK-). After treatment, leaves were collected, total RNA extracted and gene expression was evaluated by qRT-PCR. All assessed genes exhibited differential expression between susceptible and resistant plants in response to nutritional stress. In addition, genes directly involved with defense mechanisms and oxidative stress exhibited the most significant expression differences when compared with genes from nutrient metabolism. These preliminary analyses suggest that regulation of nutrient up-take and/or transport may not play a central role during coffee response, and instead the activation of defense mechanisms is the initial response to low nutrient availabilit

Checagem da pureza genética de amostras de café bourbon por meio de marcador microssatélite.

O grupo Bourbon se destaca dentre as cultivares de café arábica pelas suas características sensoriais superiores e maior valorização no mercado. Além da origem, da sustentabilidade e dos aspectos físicos e sensoriais, a rastreabilidade dos cafés diferenciados é fundamental na valorização do produto final. Este trabalho avaliou a eficiência de um marcador de DNA do tipo microssatélite ou SSR, denominado LEG2, com o objetivo de diferenciar cultivares do grupo Bourbon das principais cultivares plantadas no Brasil. Após a identificação do polimorfismo, foram avaliados a repetibilidade da técnica, o perfil de amplificação em sementes e folhas e a análise de amostras de lavouras comerciais. Esse marcador diferencia o grupo Bourbon das demais cultivares IAC, à exceção de cultivares mais antigas e pouco plantadas no País, como Typica e Amarelo de Botucatu. As cultivares Tupi IAC 1669, do IAC, e Sabiá Tardio, da Fundação Procafé, também apresentam o mesmo alelo dos cafés do grupo Bourbon para o loco LEG2. Pela simplicidade e boa resolução da técnica, o SSR-LEG2 pode ser aplicado no controle de qualidade genética nas fases de pré e pós-melhoramento do cafeeiro, e também para checar a pureza genética de amostras comerciais de café Bourbon

Raman spectroscopy of graphene under ultrafast laser excitation

The equilibrium optical phonons of graphene are well characterized in terms of anharmonicity and electron–phonon interactions; however, their non-equilibrium properties in the presence of hot charge carriers are still not fully explored. Here we study the Raman spectrum of graphene under ultrafast laser excitation with 3 ps pulses, which trade off between impulsive stimulation and spectral resolution. We localize energy into hot carriers, generating non-equilibrium temperatures in the ~1700–3100 K range, far exceeding that of the phonon bath, while simultaneously detecting the Raman response. The linewidths of both G and 2D peaks show an increase as function of the electronic temperature. We explain this as a result of the Dirac cones’ broadening and electron–phonon scattering in the highly excited transient regime, important for the emerging field of graphene-based photonics and optoelectronics

Raman spectroscopy of graphene under ultrafast laser excitation.

The equilibrium optical phonons of graphene are well characterized in terms of anharmonicity and electron-phonon interactions; however, their non-equilibrium properties in the presence of hot charge carriers are still not fully explored. Here we study the Raman spectrum of graphene under ultrafast laser excitation with 3 ps pulses, which trade off between impulsive stimulation and spectral resolution. We localize energy into hot carriers, generating non-equilibrium temperatures in the ~1700-3100 K range, far exceeding that of the phonon bath, while simultaneously detecting the Raman response. The linewidths of both G and 2D peaks show an increase as function of the electronic temperature. We explain this as a result of the Dirac cones' broadening and electron-phonon scattering in the highly excited transient regime, important for the emerging field of graphene-based photonics and optoelectronics

Effects of somatic embryogenesis on gene expression of cloned coffee heterozygous hybrids.

Cloning of superior coffee plants by somatic embryogenesis can assist breeding programs on reducing the cost and time for launch of new cultivars. This study aimed to evaluate the efficiency of this methodology for cloning coffee trees with high heterozygosity, and to gather evidence that clonal progenies are faithful copies of mother plants. Selected plants IAC1 and IAC 2 from Coffea arabica breeding populations, resistant to leaf rust and leaf miner, respectively, were cloned via indirect somatic embryogenesis. Expression of selected genes involved in biological processes potentially affected by in vitro cultivation was evaluated by quantitative analysis. Genes encoding proteins associated with maintenance of DNA integrity and control of cell cycle presented predictable expression patterns along the clonal multiplication process. There were differences in the expression pattern of genes linked to in vitro cultivation-related stress, which were observed comparing either IAC 1 and IAC2 genotypes or clones and their corresponding mother plant. Those analyses suggest that the somatic embryogenesis does not lead to major genomic instability and clones are identical copies of mother plants, even with detected differences in the expression of genes that influence the response of in vitro cultivation

DETECTION OF LAND COVER DISPLACEMENTS THROUGH TIME-SERIES ANALYSIS OF MULTISPECTRAL SATELLITE IMAGERY: APPLICATION TO DESERT

Detection of changes occurring on Earth surface has become an established practice in remote sensing science since the availability of high-resolution, global coverage, and multitemporal satellite imagery that has constantly increased during the last decades. Meanwhile, the open data policies embraced by some of the principal Earth Observation programs have boosted the spread of such analyses. This asset has attracted also the interest of the private sector which is developing strategies to exploit the potential of these data. In view of the above, we present an experimental procedure to investigate land cover displacements through an application on open multispectral imagery from the Landsat 8 and Sentinel-2 missions for desert sand dunes movements analysis. While most of the change detection techniques focus on locating changes and describing them by means of variation in the pixel spectral responses, the proposed technique aims at describing spatial and temporal patterns of displacements (i.e. directions and magnitude) applying cross-correlation analysis on a multitemporal images stack. Results of the proposed analysis are critical to a number of construction engineering operations that require sand mitigation planning and continuous site monitoring to prevent windblown sand interactions with infrastructures in the desert environment. An overview of the preliminary results is presented together with an extensive discussion on further improvements requested by the procedure. Computational steps leverage exclusively open data and free and open source GIS software thus providing large rooms to empower, replicate and improve thereof

Stimulated Raman lineshapes in the large light–matter interaction limit

Stimulated Raman scattering (SRS) represents a powerful tool for accessing the vibrational properties of molecular compounds or solid state systems. From a spectroscopic perspective, SRS is able to capture Raman spectra free from incoherent background processes and typically ensures a signal enhancement of several orders of magnitude with respect to its spontaneous counterpart. Since its discovery in 1962, SRS has been applied to develop technological applications, such as Raman-based lasers, frequency shifters for pulsed sources and Raman amplifiers. For the full exploitation of their potential, however, it is crucial to have an accurate description of the SRS processes under the large gain regime. Here, by taking as an example the stimulated Raman spectrum of a model solvent, namely liquid cyclohexane, we discuss how the spectral profiles and the lineshapes of Raman excitations critically depend on the pump excitation regime. In particular, we show that in the large light–matter interaction limit the Raman gain undergoes an exponential increase (decrease) in the red (blue) side of the spectrum, with the Raman linewidths that appear sharpened (broadened)

[Beta-2 agonists, exposure to allergens and bronchial hyperreactivity in children with allergic asthma]

The contribution of beta 2-agonist treatment per se and the effect of beta 2-agonists plus allergen exposure was evaluated in two groups of thirteen asthmatic children being treated respectively at sea level during the period of maximal allergen exposure and at high altitude in an environment free of the offending allergens. Bronchial hyperreactivity was evaluated by standardised exercise tests before and after treatment with salbutamol controlled release tablets (4 mg). Challenges were performed at the beginning and after 2 and 4 weeks of treatment. A fourth test was performed 2 days after stopping the treatment. Children treated with salbutamol at sea level (exposure to allergen) showed baseline delta PEF of 16.9 +/- 3.4 and 13.7 +/- 4.2, 20.7 +/- 4.3, 26.0 +/- 5.1 respectively for the second, third and fourth test. Children treated at high altitude showed respectively delta PEF of 34.9 +/- 5.1, 31.1 +/- 4.9, 26.5 +/- 5.4, 27.9 +/- 5.0. These data suggest that oral salbutamol per se is not responsible for an increase in bronchial responsiveness, but eventually suggest that treatment with beta 2-agonists at the same time as continued allergen exposure may be responsible for an increase in bronchial hyperresponsiveness