Selecting New \u3ci\u3eBrachiaria\u3c/i\u3e for Brazilian Pastures

Brazilian beef production relies heavily on cultivated pastures, of which about 80% are planted mainly to two Brachiaria cultivars. The narrowness of diversity associated with reproduction by apomixis of most plants in this genus prompted an intense search for new cultivars amongst recently collected and introduced ecotypes from Africa. This paper reports results for a three-year evaluation of 21 pre-selected ecotypes in two typical Cerrado ecosystems. Plots, replicated four times, were seeded in rows and cut every 6 weeks during the rainy season followed by a cut in the middle and one at the end of the dry season. Significant differences were found between ecotypes, seasons and years for total, leaf or leaf + stem dry matter production, percentage of leaves, leaf: stem ratio and regrowth rate. Ecotypes differed in the two ecosystems for percentage of leaves, leaf: stem ratio and regrowth. Superior ecotypes (BRA004308, 003361, 002844, 003204, 003441) could be identified and were equally advantageous in both ecosystems

Molecular determinants of the SARS-CoV-2 fusion peptide activity

The COVID-19 pandemic, caused by the SARS-CoV-2 virus, emerged in late 2019 and quickly spread worldwide, resulting in over 125 million infections and 2.7 million deaths as of March 2021 accordingly to the World Health Organization. Despite the great advances achieved by the scientific community in providing crucial information about this virus, we are still far from completely understanding it. SARS-CoV-2 is an enveloped virus, meaning that it is encapsulated by a lipid membrane, which needs to be fused to the host membrane to begin the infection process. Fusion between viral and host membrane is catalyzed by the spike (S) glycoprotein. The S-protein is composed of essential elements for the infection mechanism, namely the receptor-binding domain known to bind to angiotensin-converting enzyme 2 during the viral entry pathway. Another important region, known as the fusion peptide (FP), plays an essential part in the fusion mechanism, by inserting into and disturbing the host membrane. There is still not a consensus among scientists in terms of the fusion peptide location on the S-protein sequence, with two major candidate regions having been proposed. We recently used a machine learning-based tool developed by us to identify viral FPs with accuracies over 85%. With this tool a putative FP, previously suggested in the literature, has been identified, as well as other proposals including the requirement of more than one FP. To further address this question, we are performing a systematic analysis of the SARS-CoV-2 putative FPs, using Molecular Dynamics (MD) simulations, which provide a detailed perspective of how these peptides insert and interact with the membrane. In parallel, we are characterizing these systems experimentally. Additionally we are exploring therapeutic strategies targeting these regions. Given the major role of the FP in the virus infection process, this work provides relevant insights and contributes to the fight against COVID-19.info:eu-repo/semantics/publishedVersio

First Occurrence and Population Dynamics of Blissus pulchellus (Hemiptera: Blissidae) in Brazil: a new pest of pastures in Roraima.

Cattle production is one of the main economic activities in the state of Roraima, and insect pest attacks in pastures have a negative effect on this sector in the region. Little is known about the species that cause damage to forage fields in the state. This study presents the first report of the occurrence of the chinch bug Blissus pulchellus Montandon (Hemiptera: Blissidae) in Roraima, Brazil and a description of the population dynamics of this pest in pasture areas in this state. Pasture areas were sampled in nine municipalities of Roraima to detect the insect. The population dynamics study was conducted for two years in Alto Alegre municipality, two of which have Brachiaria brizantha cv. Marandu and one of Megathrysus maximus cv. Mombaça (Poaceae) crops. Blissus pulchellus was found in all sampled areas, except in Rorainópolis and São João da Baliza. High densities of this bug were found in in Alto Alegre. This is the first report of B. pulchellus in Brazil. The factors that affect the population dynamics and the damage caused by this insect pest to pastures as well as the risk of dispersal of this pest in Brazil are discussed

Planos de amostragem de ovos de cigarrinhas em pastagens de Brachiaria decumbens

A sampling study of spittlebug eggs in pastures of Brachiaria decumbens was conducted by using a sample unit of 15 x 15 cm. The number of samples required for a certain level of precision was inversely proportional to population density. A crude estimate of number of samples necessary for 10, 15 and 20% of precision were 133,59 and 33, respectively. A study of sampling variation showed that differences between plots were much more important than the block differences; therefore plot to plot variation must be considered while sampling spittlebug eggs. The distribution pattern of numbers of eggs per 225 cm2 of pasture fitted the negative binomial series. The sequential sampling plan presented here would reduce the sampling time over the conventional (fixed sample numbers) sampling.Foi conduzido um estudo sobre amostragem de ovos de cigarrinhas em pastagens de Brachiaria decumbens com o uso de uma unidade de amostragem de 15 x 15 cm. O número de amostras necessárias para um certo nível de precisão foi inversamente relacionado à densidade da população. Uma estimativa grosseira mostrou a necessidade de 133 amostras para se obter um nível de 10% de precisão, 59 para 15% e 33 para 20%. Um estudo sobre a variação na amostragem mostrou que a variação entre as parcelas foi mais importante do que entre os blocos; e assim sendo, a variação entre parcelas deve ser considerada na amostragem de ovos de cigarrinhas. O número de ovos por 225 cm2 de área de pastagens mostrou uma distribuição do tipo binomial negativa. Um plano de amostragem tipo sequencial, apresentado no presente trabalho, reduziria o tempo gasto na amostragem em comparação à amostragem convencional onde o número de amostras é fixo

Evaluation of an apomictic genotype of Brachiaria brizantha leading to cultivar release and protection.

The evaluation progress leading to cultivar development of a forage grass is a long-term investment, which requires a multidisciplinary team.Capa e conteúdo em inglês. Título em inglês: XX International Congress on Sexual Plant Reproduction

Indkomne bøger fra oktober 1999 til september 2000

Head and neck cancer (HNC) has a high incidence in Brazil, with cancer of the oral cavity being one of the five most common cancers among Brazilians. Alcohol and tobacco consumption may contribute to synchronous or metachronous HNC and esophageal cancer. The early detection of superficial esophageal cancer and dysplasia in asymptomatic patients with HNC, after successfully treating the primary cancer, may provide an effective cure. A prospective study involving 60 patients with HNC was carried out at the State University of Campinas (UNICAMP) to screen for superficial esophageal cancer and dysplasia using endoscopy and a 2% lugol dye solution followed by biopsy of the suspicious areas. Five patients (8.3%) had superficial esophageal cancer, which was diagnosed as intraepithelial carcinoma in three of them (5.0%). In four patients, the superficial esophageal cancer was synchronous, and in one it was metachronous to HNC. Five patients (8.3%) had dysplasias in the esophageal epithelium (three were classified as mild and two as moderate). These results demonstrate the value of endoscopic screening of the esophagus using lugol dye in patients with HNC, particularly because superficial esophageal cancer is extremely difficult to detect by conventional methods in asymptomatic patients.22170-

Binary orbits as the driver of γ-ray emission and mass ejection in classical novae

Classical novae are the most common astrophysical thermonuclear explosions, occurring on the surfaces of white dwarf stars accreting gas from companions in binary star systems. Novae typically expel �10,000 solar masses of material at velocities exceeding 1,000 km/s. However, the mechanism of mass ejection in novae is poorly understood, and could be dominated by the impulsive flash of the thermonuclear runaway, prolonged optically thick winds, or binary interaction with the nova envelope. Classical novae are now routinely detected in GeV gamma-rays, suggesting that relativistic particles are accelerated by strong shocks in nova ejecta. Here we present high-resolution imaging of the gamma-ray-emitting nova V959 Mon at radio wavelengths, showing that its ejecta were shaped by binary motion: some gas was expelled rapidly along the poles as a wind from the white dwarf, while denser material drifted out along the equatorial plane, propelled by orbital motion. At the interface between the equatorial and polar regions, we observe synchrotron emission indicative of shocks and relativistic particle acceleration, thereby pinpointing the location of gamma-ray production. Binary shaping of the nova ejecta and associated internal shocks are expected to be widespread among novae, explaining why many novae are gamma-ray emitters

Caracterização físico-química de frutos de matrizes de pequizeiro (Caryocar brasiliense Camb., Caryocaraceae.

Resumo ? No presente trabalho objetivou-se a caracterização físico-quí- mica de frutos de genótipos de pequizeiro pertencentes ao Banco Ativo de Germoplasma da Embrapa Cerrados, Planaltina, DF, quanto à cor, massa e comprimento do fruto inteiro e dos pirênios, diâmetro maior e menor do fruto, formato do fruto, espessura da casca, diâmetro longitudinal e equatorial dos pirênios, quantidade de pirênios por fruto, rendimento de pirênios, acidez ti- tulável, pH, sólidos solúveis, extrato etéreo e cinzas da polpa dos pirênios. A análise de agrupamento indicou a formação de cinco, sete e oito grupos de genótipos de pequi similares, em função das variáveis de cor, físico-química e física, respectivamente. Para a cor, destacaram-se os genótipos E32, F46, J41, E44, F18, F32, F47, G18 e L3, para os atributos físico-químicos, os ge- nótipos E6, F7, I23 e J27 e, para os atributos físicos, os genótipos E5, K28 e K48. Os genótipos que mais se destacaram, independentemente dos atribu- tos avaliados, foram E6, F7 e I23, apresentando frutos com boa coloração, altos teores para as variáveis físico-químicas e valores intermediários para o tamanho do fruto. Os resultados obtidos no presente trabalho subsidiarão es- tudos visando à seleção e ao melhoramento da espécie para fins comerciais