Levantamento fitossociológico das comunidades de plantas infestantes em áreas de produção de arroz irrigado cultivado sob diferentes sistemas de manejo Phyto-sociological survey of weed communities in flooded rice areas cultivated under different management systems

O presente trabalho de pesquisa teve como objetivo identificar a composição florística de comunidades de plantas daninhas presentes em áreas agrícolas de várzea, manejadas em diferentes sistemas. O trabalho foi desenvolvido em áreas de produção de arroz irrigado das cooperativas: Cooperativas Mista Rural Vale do Javaés e Cooperativa Agroindustrial Rio Formoso, em Formoso do Araguaia-TO. Foram separadas três áreas de 1 ha, sendo: 1 - área sem rotação de culturas (arroz/pousio) há mais de cinco anos; 2 - área com rotação de culturas (arroz/soja) há mais de cinco anos; 3 - área com rotação de culturas (arroz/melancia) há mais de dois anos. Para caracterização e estudo fitossociológico da comunidade infestante foi utilizado, como unidade amostral, um quadro (1,0 x 1,0 m), lançado aleatoriamente dentro da área de estudo (método do quadrado inventário), por meio de um caminhamento em ziguezague. Na área sem rotação, foram identificadas 8 famílias e 16 espécies, destacando-se a família Poaceae com maior número espécies; Fimbristylis miliacea (Cyperaceae) foi a espécie com o maior índice de importância relativa (84,46%). Na área com rotação arroz/soja, foram identificadas 8 famílias e 12 espécies, destacando-se as famílias Poaceae e Cyperaceae com maior número espécies; Cyperus esculentus (Cyperaceae) foi a espécie com o maior índice de importância relativa (91,4%). Na área com rotação arroz/melancia foram identificadas seis famílias e oito espécies, destacando-se as famílias Euphorbiaceae e Lamiaceae com maior número espécies; Physalis angulata (Solanaceae) foi a espécie com o maior índice de importância relativa (153,1%), seguida por Eclipta alba (Compositae) e Hyptis lophanta (Lamiaceae), com 40,45 e 37,6%, respectivamente.<br>This research aimed to identify the floristic composition of weed communities present in lowland agricultural areas under different management systems. The trial was carried out in flooded rice areas of two different co-ops located in Formoso do Araguaia, Tocantins, Brazil: Mista Rural Vale do Javaés Co-op and Agroindustrial Rio Formoso Co-op. Three different 1 ha areas were selected: 1 - area under 5- year no crop rotation system (rice/fallow); 2 - area under 5- year rice/soybean crop rotation system; and 3 - area under 2- year rice/water-melon crop rotation system. The characterization and phyto-sociological studies of the weed community were carried out using square samples of 1.0 x 1.0 meter randomly placed inside each selected area (Inventory Square Method). Eight families and 16 species were identified in the no-crop rotation area, with the family Poaceae presenting the largest number of species and Fimbristylis miliacea (Cyperaceae) presenting the highest relative importance value (84.46%). The 5-year rice soybean crop rotation system area had 8 families and 12 species with the Poaceae and Cyperaceae presenting the largest number of species and Cyperus esculentus (Cyperaceae) the highest relative importance value (91. 40 %). Six families and 8 species were identified in the 2-year rice/water-melon crop rotation system area, with the Euphorbiaceae and Lamiaceae families presenting the largest number of species. Physalis angulata (Solanaceae) showed the highest relative importance value (153.10%), followed by Eclipta alba (Compositae) and Hyptis lophanta (Lamiaceae) with a relative importance value of 40.50% and 37.60%, respectively

Diversidade da comunidade de plantas invasoras em sistemas agroflorestais com café em Turrialba, Costa Rica Diversity of weed community in agroforestry systems with coffee in Turrialba, Costa Rica

O objetivo deste trabalho foi avaliar a diversidade de plantas invasoras, em sistemas agroflorestais com cafeeiros (Coffea arabica L.) e em cafezal a pleno sol, sob manejo orgânico e convencional. Foram avaliados 20 tratamentos no delineamento de blocos ao acaso, em parcelas subdivididas no tempo, com três repetições. Os tratamentos corresponderam à combinação entre sistemas agroflorestais e quatro níveis de manejo, baseados na intensidade das práticas e aplicação de insumos: alto e médio convencional, médio e baixo orgânico. Em julho de 2002 e setembro de 2005 foi realizado o levantamento de plantas invasoras. Determinaram-se a riqueza, abundância, diversidade e eqüitabilidade. Observou-se redução nos valores médios de riqueza, abundância, diversidade e eqüitabilidade, em que os menores valores foram encontrados no tratamento com manejo alto convencional. Houve redução na freqüência das trepadeiras, ciperáceas e espécies de folhas estreitas (má cobertura), e aumento das espécies de folhas largas (boa cobertura) e gramíneas. Nas duas épocas, os maiores percentuais de pontos com solo descoberto foram encontrados no tratamento alto convencional, e os menores percentuais foram encontrados em todos os tratamentos com manejo médio e baixo orgânico, e em três dos sete tratamentos com manejo médio convencional. Tais resultados demonstram que onde há aplicação freqüente de herbicida, a presença de árvores não evita exposição do solo.<br>The objective of this work was to evaluate the floristic composition of spontaneous species in coffee (Coffea arabica L.) cultivated in full sun and in agroforestry systems, under organic and conventional management. Twenty treatments were evaluated in a randomized complete block design, in a split plot in time, with three replicates. The treatments corresponded to combinations between types of agroforestry systems and four management system levels, based on practice intensity and inputs application: high and medium conventional, medium and low organic management. In July 2002 and September 2005 a spontaneous species survey was carried out. Richness, abundance, diversity and evenness index were determined. Reductions were observed in richness, abundance, diversity, and evenness values, and the smallest ones were found in high conventional treatment. There was reduction in the relative frequency of climbing plants, Cyperaceae, and monocot species (poor cover), and increase in broad-leaf species (good cover) and grasses. In both seasons, the highest percentages of points with bare soil were found in the high conventional treatment, while the lowest percentages were found in all treatments under medium and low organic management, and in three out of the seven treatments under medium conventional management. These results demonstrate that in treatments where herbicides are frequently applied, the presence of trees does not prevent the soil from being exposed

Transcriptome analysis of the acoelomate human parasite Schistosoma mansoni

Schistosoma mansoni is the primary causative agent of schistosomiasis, which affects 200 million individuals in 74 countries. We generated 163,000 expressed-sequence tags (ESTs) from normalized cDNA libraries from six selected developmental stages of the parasite, resulting in 31,000 assembled sequences and 92% sampling of an estimated 14,000 gene complement. By analyzing automated Gene Ontology assignments, we provide a detailed view of important S. mansoni biological systems, including characterization of metazoa-specific and eukarya-conserved genes. Phylogenetic analysis suggests an early divergence from other metazoa. The data set provides insights into the molecular mechanisms of tissue organization, development, signaling, sexual dimorphism, host interactions and immune evasion and identifies novel proteins to be investigated as vaccine candidates and potential drug targets

Comparative Genomics Of Two Leptospira Interrogans Serovars Reveals Novel Insights Into Physiology And Pathogenesis

Leptospira species colonize a significant proportion of rodent populations worldwide and produce life-threatening infections in accidental hosts, including humans. Complete genome sequencing of Leptospira interrogans serovar Copenhageni and comparative analysis with the available Leptospira interrogans serovar Lai genome reveal that despite overall genetic similarity there are significant structural differences, including a large chromosomal inversion and extensive variation in the number and distribution of insertion sequence elements. Genome sequence analysis elucidates many of the novel aspects of leptospiral physiology relating to energy metabolism, oxygen tolerance, two-component signal transduction systems, and mechanisms of pathogenesis. A broad array of transcriptional regulation proteins and two new families of afimbrial adhesins which contribute to host tissue colonization in the early steps of infection were identified. 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Genome features of Leptospira interrogans serovar Copenhageni

We report novel features of the genome sequence of Leptospira interrogans serovar Copenhageni, a highly invasive spirochete. Leptospira species colonize a significant proportion of rodent populations worldwide and produce life-threatening infections in mammals. Genomic sequence analysis reveals the presence of a competent transport system with 13 families of genes encoding for major transporters including a three-member component efflux system compatible with the long-term survival of this organism. The leptospiral genome contains a broad array of genes encoding regulatory system, signal transduction and methyl-accepting chemotaxis proteins, reflecting the organism's ability to respond to diverse environmental stimuli. The identification of a complete set of genes encoding the enzymes for the cobalamin biosynthetic pathway and the novel coding genes related to lipopolysaccharide biosynthesis should bring new light to the study of Leptospira physiology. Genes related to toxins, lipoproteins and several surface-exposed proteins may facilitate a better understanding of the Leptospira pathogenesis and may serve as potential candidates for vaccine