Silicon sources for studies of rice plants in nutrient solutions

The objective of this work was to evaluate the effects of various Si sources currently used in studies of Si doses in nutrient solutions on dry matter yield and the accumulation of nutrients and Si in rice plants. Treatments of rice plants with three sources of Si (monossilicic acid, sodium metasilicate, potassium metasilicate) and a treatment without Si were allocated in a randomized block design with ten replications. After 39 days in the nutrient solution, the following traits were evaluated: leaf area, leaf specific mass, dry matter yield of roots and shoots, and levels of K, Na, and Si in leaves and roots. Si increased leaf area, leaf specific mass, and dry matter yield of shoots and roots regardless of the Si source. Levels of Si in leaves and roots were significantly higher in relation to the control treatment but no significant difference among Si sources was identified. It was also observed that K and Na were adequately balanced across the treatments. Thus, a cheaper and easier to obtain Si source, such as sodium metasilicate and potassium metasilicate, may be chosen to carry out studies of Si additions to nutrient solutions

Produção e qualidade de rosas em razão de doses de boro aplicadas no substrato

Muitos trabalhos têm demonstrado os efeitos da aplicação do boro (B) em variadas culturas; entretanto, poucos registros demonstram seus efeitos na produção de rosas. Objetivou-se com este experimento avaliar os efeitos de doses de B na produção e qualidade de rosas (Rosa hybrida cv. Shiny Terrazza®) em vaso. Os tratamentos foram cinco doses de B (0, 1, 4, 8 e 16 mg kg-1), aplicadas no substrato, em delineamento de blocos casualizados, com cinco repetições. Foram avaliados: número de flores por planta; número de folhas por haste floral; produção de matéria seca de raízes, folhas e flores; altura da planta; número de dias para o florescimento; comprimento do botão floral; e diâmetro e longevidade floral. Além disso, foram determinados os teores foliares de clorofila total e B e os sintomas de toxidez desse elemento. Verificou-se efeito significativo das doses de B na maioria das variáveis avaliadas, excetuando-se a altura das plantas, o número de flores por planta, a longevidade floral e a produção de matéria seca de raízes. O teor foliar de B aumentou linearmente em função das doses desse elemento. Houve incremento na produção e qualidade das flores com a aplicação do B, com redução do número de dias para o florescimento. Foram verificados sintomas de toxidez causado pelo B a partir da dose de 4 mg kg-1. Esses sintomas foram caracterizados por manchas do tipo encharcamento, iniciando nas margens do limbo foliar, com essas evoluindo para clorose e posterior necrose; na maior dose ocorreu queda de folhas. Essa queda foi responsável pela diminuição do número de folhas por haste no final do ciclo, a partir da dose de 8 mg kg-1 de B. As plantas com sintomas de toxidez apresentaram teores foliares de B acima de 200 mg kg-1, enquanto as sadias (controle), de 65 a 89 mg kg-1.Many studies have shown the effects of boron (B) application on various crops; however, results on roses are scarce. The aim of this experiment was to evaluate the effects of B on the production and quality of roses (Rosa hybrida Shiny Terrazza®) under controlled conditions. Treatments consisted of five rates of B (0, 1, 4, 8 and 16 mg kg-1) applied in the substrate in a randomized block design with five replicates. We evaluated the cycle; number of flowers per plant; number of leaves per flower stem; dry matter production of roots, leaves and flowers; plant height; length of the floral bud; and flower diameter and longevity. In addition, total chlorophyll and B content in the leaves and symptoms of B toxicity in the plants were also determined. There was a significant effect of B application rates on most of the variables, with the exception of plant height, number of flowers per plant, flower longevity, and root dry matter production. Leaf B content increased in a linear manner with increasing application rates of B in the range of 0 to 16 mg kg-1. There was an increase in flower production and quality with the application of B, and a reduction in the number of days to flowering. Boron toxicity symptoms were observed at B rates higher than 4 mg kg-1. These symptoms were characterized by soaked spots beginning at the edges of the leaf blade, with the spots evolving to chlorosis and subsequent necrosis. At the highest rate of B application, there was dropping of leaves. This leaf dropping was responsible for the decreased number of leaves per floral stem at the end of the cycle as of B application rates of 8 mg kg-1. Plants showing symptoms of toxicity had leaf B contents above 200 mg kg-1, while healthy plants (control) had B contents ranging from 65 to 89 mg kg-1

ESTRUTURA POPULACIONAL E REGENERAÇÃO DE ESPÉCIES ARBÓREAS NA FLORESTA NACIONAL DE SÃO FRANCISCO DE PAULA, RIO GRANDE DO SUL

The aim of this study was to characterize the population structure and aspects of regeneration of Araucaria angustifolia (Bertol.) Kuntze, Blepharocalyx salicifolius (Kunth) O. Berg and Ilex paraguariensis A. St.-Hil. in different environmental and disturbance conditions in the National Forest of São Francisco de Paula, RS state. Six conglomerates of one hectare were used, with 16 plots (20 x 20 m) each, where the species were sampled in three size classes. The size class II (SC II – diameter at breast height (DBH) ≥ 9.55 cm) was sampled in 96 plots, the SC I (4.8 ≤ DBH < 9.55 cm) in 36 subplots of 10 x 10 m, and the established natural regeneration (ENR) (1 ≤ DBH < 4.8 cm) in 36 cells of 3.16 x 3.16 m. The seedling bank (SB - height ≥ 30 cm and DBH < 1 cm), the seed rain (SR) and the soil seed bank (SSB) were sampled in all plots of 20 x 20 m. The data were analysed by taking into account all the different vegetation groups together and separately for each cluster identified in a previous study. For SC II, the frequency distribution of DBH was analysed combined with the analysis of absolute density and frequency for all different life stages (SR, SSB, SB, ENR, SC I and SC II). The results indicated high variability in density of these species among the different life stages and environmental conditions. Araucaria angustifolia presented gaps in the regeneration process in areas that had low disturbance records, not presenting the "reverse-J" distribution (SC II) and with lower regeneration capacity in relation to the other species (SR, SSB and SB). Ilex paraguariensis and Blepharocalyx salicifolius seemed to present higher population stability in environment with low level of human interference (SC II). The first species demonstrated preference for soils with good drainage, while the second species for humid soils. Moreover, gaps in the regeneration process of different populations were detected and changed according to environmental conditions and disturbance records. Therefore, the results suggest the importance of taking into account the different vegetation groups, the species auto-ecology and to apply possible interventions that aim to improve regeneration and balance the population dynamics of these species.Este estudo teve como objetivo caracterizar a estrutura populacional e os aspectos da regeneração de Araucaria angustifolia (Bertol.) Kuntze, Blepharocalyx salicifolius (Kunth) O. Berg e Ilex paraguariensis A. St.-Hil em diferentes condições ambientais e histórico de perturbação na Floresta Nacional de São Francisco de Paula - RS. Foram utilizados seis conglomerados de um hectare, com 16 parcelas (20 x 20 m) cada, nos quais foram amostradas as espécies em três classes de tamanho. A classe de tamanho II (CT II - diâmetro a altura do peito (DAP) ≥ 9,55 cm) foi inventariada nas 96 parcelas, a CT I (4,8 ≤ DAP < 9,55 cm) em 36 subparcelas de 10 x 10 m e a regeneração natural estabelecida (RNE) (1 ≤ DAP < 4,8 cm) em 36 células de 3,16 x 3,16 m. Em todas as parcelas de 20 x 20 m foram avaliados o banco de plântulas (BP - altura ≥ 30 cm e DAP < 1 cm), a chuva de sementes (CS) e o banco de sementes do solo (BS). Os dados foram analisados considerando todos os ambientes conjunta e separadamente para os agrupamentos identificados em estudo prévio na área. Foram avaliadas a estrutura diamétrica para a CT II e densidade e frequência absoluta para todas as etapas do ciclo de vida (CS, BS, BP, RNE, CT I e CT II). Os resultados indicaram grande variabilidade na densidade destas espécies nos diferentes ciclos de vida e ambientes florestais. Araucaria angustifolia demonstrou falhas no processo de regeneração em ambiente com menor histórico de perturbação, não apresentando padrão de distribuição “J invertido” (CT II) e menor capacidade de regeneração em relação às demais espécies nos mecanismos de regeneração (CS, BS e BP). Ilex paraguariensis e Blepharocalyx salicifolius apresentaram melhor estabilidade populacional em ambiente com menor nível de interferência antrópica (CT II). A primeira espécie apresentou melhores condições de regeneração em ambientes de solo com boa drenagem e a segunda espécie demonstrou preferência para solo mais úmido. Além disso, falhas no processo de regeneração das populações foram detectadas e variaram de acordo com as condições ambientais e o histórico de perturbação de cada área. Assim, identifica-se a importância de considerar os diferentes ambientes florestais, a autoecologia das espécies e de aplicar possíveis intervenções que visem melhorar a regeneração e equilibrar a dinâmica populacional destas espécies

The Genome of Anopheles darlingi, the main neotropical Malaria vector

Anopheles darlingi is the principal neotropical malaria vector, responsible for more than a million cases of malaria per year on the American continent. Anopheles darlingi diverged from the African and Asian malaria vectors ∼100 million years ago (mya) and successfully adapted to the New World environment. Here we present an annotated reference A. darlingi genome, sequenced from a wild population of males and females collected in the Brazilian Amazon. A total of 10 481 predicted protein-coding genes were annotated, 72% of which have their closest counterpart in Anopheles gambiae and 21% have highest similarity with other mosquito species. In spite of a long period of divergent evolution, conserved gene synteny was observed between A. darlingi and A. gambiae. More than 10 million single nucleotide polymorphisms and short indels with potential use as genetic markers were identified. Transposable elements correspond to 2.3% of the A. darlingi genome. Genes associated with hematophagy, immunity and insecticide resistance, directly involved in vector–human and vector–parasite interactions, were identified and discussed. This study represents the first effort to sequence the genome of a neotropical malaria vector, and opens a new window through which we can contemplate the evolutionary history of anopheline mosquitoes. It also provides valuable information that may lead to novel strategies to reduce malaria transmission on the South American continent. The A. darlingi genome is accessible a

Transcriptional profiles of the human pathogenic fungus paracoccidioides brasiliensis in mycelium and yeast cells

This work was supported by MCT, CNPq, CAPES, FUB, UFG, and FUNDECT-MS. PbGenome Network: Alda Maria T. Ferreira, Alessandra Dantas, Alessandra J. Baptista, Alexandre M. Bailão, Ana Lídia Bonato, André C. Amaral, Bruno S. Daher, Camila M. Silva, Christiane S. Costa, Clayton L. Borges, Cléber O. Soares, Cristina M. Junta, Daniel A. S. Anjos, Edans F. O. Sandes, Eduardo A. Donadi, Elza T. Sakamoto-Hojo, Flábio R. Araújo, Flávia C. Albuquerque, Gina C. Oliveira, João Ricardo M. Almeida, Juliana C. Oliveira, Kláudia G. Jorge, Larissa Fernandes, Lorena S. Derengowski, Luís Artur M. Bataus, Marcus A. M. Araújo, Marcus K. Inoue, Marlene T. De-Souza, Mauro F. Almeida, Nádia S. Parachin, Nadya S. Castro, Odair P. Martins, Patrícia L. N. Costa, Paula Sandrin-Garcia, Renata B. A. Soares, Stephano S. Mello, and Viviane C. B. ReisParacoccidioides brasiliensis is the causative agent of paracoccidioidomycosis, a disease that affects 10 million individuals in Latin America. This report depicts the results of the analysis of 6,022 assembled groups from mycelium and yeast phase expressed sequence tags, covering about 80% of the estimated genome of this dimorphic, thermo-regulated fungus. The data provide a comprehensive view of the fungal metabolism, including overexpressed transcripts, stage-specific genes, and also those that are up- or down-regulated as assessed by in silico electronic subtraction and cDNA microarrays. Also, a significant differential expression pattern in mycelium and yeast cells was detected, which was confirmed by Northern blot analysis, providing insights into differential metabolic adaptations. The overall transcriptome analysis provided information about sequences related to the cell cycle, stress response, drug resistance, and signal transduction pathways of the pathogen. Novel P. brasiliensis genes have been identified, probably corresponding to proteins that should be addressed as virulence factor candidates and potential new drug targets