Montagem De Comunidades: Conceitos, Domínio E Estrutura Teórica

Community assembly refers to any ecological process that operates to select species from a regional pool and put them together in local communities. Initially, Diamond (1975) proposed a community assembly model based on rules explaining the checkerboard distribution of co-occurring bird species in New Guinea archipelago. By that time, the assembly rules proposed interspecific competition as the only plausible explanation for the patterns observed. However, the lack of testable predictions, inappropriate statistical analyses and, mainly, the absence of alternative hypotheses have represented an obstacle for the theory development. With the introduction of phylogenetic/functional analyses in community studies, a meaningful increase of published papers on community assembly has been noticed, mainly due to the development of models providing more predictive power to assembly processes. Hence, we decided to elaborate a critical review about the conceptual progress in the community assembly theory. We point out that a) the community assembly theory has enhanced its predictive power when it became to be associated with solid statistics; b) the hypothesis test by null models has been reinforced as a consistent data analysis method applied in many studies; and c) the neutral theory has been used as a satisfactory alternative to the coexistence hypothesis by deterministic niche-based processes. However, the community assembly theory is not fully mature yet but has a high potential of near-future development, mainly through the consolidation of its conceptual base. We hope that our review can help in this development by systematizing the community assembly theory and clarifying some misunderstood and/or so-far poorly applied concepts. © 2016, Universidade Federal do Rio de Janeiro (UFRJ). All rights reserved.20111

Propolis Extract In Postharvest Conservation Of Solo Papaya Cv. 'golden'

The high perishability of papaya (Carica papaya L.) reduces the lifespan as well as limits marketing. Coating fruit is an alternative process to aid food preservation. The objective of this study was to evaluate the effects of propolis extract coating on physicochemical characteristics of papaya stored at room temperature. Solo papayas cv. 'Golden' were randomly divided into five postharvest treatments: three forms of dip-coating (70% alcohol, hydroalcoholic extract of propolis at 2.5%, and hydroalcoholic extract of propolis at 5%) and two controls (one uncoated and one with refrigerated uncoated fruit). Each four days, weight loss, fruit firmness, soluble solids (SS), titratable acidity (TA), SS/ TA ratio, and hydrogen potential (pH) were evaluated throughout 12 days of storage. A sensory analysis was performed on the fourth day of storage, being appraised by untrained tasters through acceptance testing. Refrigerated, 2.5% propolis, and 5% propolis treatments promoted the lowest weight losses. Flesh firmness of 5% propolis treatment was superior to that of control, alcohol, and 2.5% propolis treatments. Moreover, 5% propolis treatment achieved a great SS, differing only from alcohol treatment. Both TA and SS/TA had no variations among treatments, but along storage time. Flesh pH of refrigerated papaya showed significant differences in relation to other treatments. Also, refrigerated fruit presented chilling injury symptoms. Propolis-coated papaya showed sensory acceptability similar to those of the other treatments on the 4th day of storage. Therefore, propolis coating renders Solo papaya cv. 'Golden' a promising alternative to control fruit weight losses and firmness.3764039405

Trans-sialidase from Trypanosoma cruzi enhances the adhesion properties and fibronectin-driven migration of thymocytes

In experimental Trypanosoma cruzi infections, severe thymic atrophy leads to release of activated CD4+CD8+ double-positive (DP) T cells to the periphery. In humans, activated DP T cells are found in the blood in association with severe cardiac forms of human chronic Chagas disease. The mechanisms underlying the premature thymocyte release during the chagasic thymic atrophy remain elusive. We tested whether the migratory properties of intrathymic thymocytes are modulated by the parasite trans-sialidase (TS). We found that TS affected the dynamics of thymocytes undergoing intrathymic maturation, and these changes were accompanied by an increase in the number of recent DP thymic emigrants in the peripheral lymphoid organs. We demonstrated that increased percentages of blood DP T cell subsets were associated with augmented antibody titers against TS in chagasic patients with chronic cardiomyopathy. In vitro studies showed that TS was able to activate the MAPK pathway and actin filament mobilization in thymocytes. These effects were correlated with its ability to modulate the adhesion of thymocytes to thymic epithelial cells and their migration toward extracellular matrix. These findings point to effects of TS that could influence the escape of immature thymocytes in Chagas disease.Fil: Nardy, Ana Flávia F.R.. Universidade Federal do Rio de Janeiro; BrasilFil: Silva Filho, Joao Luiz da. Universidade Federal do Rio de Janeiro; BrasilFil: Perez, Ana Rosa. Universidad Nacional de Rosario. Facultad de Ciencias Médicas. Instituto de Inmunología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Meis, Juliana de. Instituto Oswaldo Cruz; BrasilFil: Farias de Oliveira, Désio Aurélio. Instituto Oswaldo Cruz; BrasilFil: Penha, Luciana. Universidade Federal do Rio de Janeiro; BrasilFil: Oliveira, Isadora de Araújo. Universidade Federal do Rio de Janeiro; BrasilFil: Dias, Wagner B.. Universidade Federal do Rio de Janeiro; BrasilFil: Todeschini, Adriane. Universidade Federal do Rio de Janeiro; BrasilFil: Freire de Lima, Célio Geraldo. Universidade Federal do Rio de Janeiro; BrasilFil: Bellio, Maria. Universidade Federal do Rio de Janeiro; BrasilFil: Caruso Neves, Celso. Universidade Federal do Rio de Janeiro; BrasilFil: Pinheiro, Ana Acácia. Universidade Federal do Rio de Janeiro; BrasilFil: Takiya, Christina Maeda. Universidade Federal do Rio de Janeiro; BrasilFil: Bottasso, Oscar Adelmo. Universidad Nacional de Rosario. Facultad de Ciencias Médicas. Instituto de Inmunología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Savino, Wilson. Instituto Oswaldo Cruz; BrasilFil: Morrot, Alexandre. Universidade Federal do Rio de Janeiro; Brasi