Impacto da toxina Bt sobre comunidades de leveduras epifiticas.

Resumo: O cultivo de milho (Zea mays) está entre as mais importantes culturas do mundo, e o Brasil está em terceiro lugar na produção mundial. Com o advento da biotecnologia foram desenvolvidas plantas geneticamente modificadas que expressam a toxina Bt; conferindo à planta hospedeira alto padrão de resistência a insetos evitando, assim, grandes perdas de produção. O objetivo deste trabalho foi avaliar a influência da toxina Bt presente nas folhas de milho transgênico AG8088 YG e compará-lo com as variedades não transgênicas AG8088 e BRS 1055, quanto ao numero de colônias de leveduras epifíticas apresentadas, através da técnica de diluição e espalhamento sobre superfície. A variedade transgênica de milho reduziu, significativamente, a quantidade de colônias de leveduras epifíticas, quando comparado com as demais variedades não transgênicas. Com relação à diversidade de leveduras analisadas de acordo com a morfologia das colônias, verificou-se variação inexpressiva frente à transgênica. Abstract: Corn cultivation (Zea mays) is among the most important ones of the world and Brazil holds third place in world's production. Due to biotechnology genetically-modified plants which present the Bt toxin have been developed, giving a high pattern of resistance to their host insect, thus avoiding large production losses. The objective of this study was to evaluate the influence of Bt toxin in the leaves of transgenic corn YG AG8088 on epiphytic yeast communities, through the technique of dilution and spreading on the surface. The transgenic variety reduced the amount of epiphytic yeasts colonies, compared to all other non-transgenic varieties. Comparing both treatments, it was obtained an inexpressive variation in the diversity of yeasts colonies morphology on transgenic group

Cultivo in vitro de ápices caulinares de limoeiro Rugoso Mazoe em meio WPM suplementado com ANA e BAP.

Apesar da posição de destaque que detém a citricultura brasileira, são diversas as doenças sistêmicas que podem afetar a sua produção. As técnicas biotecnológicas podem reparar os problemas associados ao melhoramento das espécies cítricas, a exemplo do cultivo de ápices caulinares, que vem sendo bastante utilizada na produção de plantas livres de doenças. O emprego desta técnica, avaliando-se as condições de cultivo, pode fornecer melhores possibilidades para o desenvolvimento de plantas de citros via organogênese

Convex Independence in Permutation Graphs

A set C of vertices of a graph is P_3-convex if every vertex outside C has at most one neighbor in C. The convex hull \sigma(A) of a set A is the smallest P_3-convex set that contains A. A set M is convexly independent if for every vertex x \in M, x \notin \sigma(M-x). We show that the maximal number of vertices that a convexly independent set in a permutation graph can have, can be computed in polynomial time

Noncommutative Conformally Coupled Scalar Field Cosmology and its Commutative Counterpart

We study the implications of a noncommutative geometry of the minisuperspace variables for the FRW universe with a conformally coupled scalar field. The investigation is carried out by means of a comparative study of the universe evolution in four different scenarios: classical commutative, classical noncommutative, quantum commutative, and quantum noncommutative, the last two employing the Bohmian formalism of quantum trajectories. The role of noncommutativity is discussed by drawing a parallel between its realizations in two possible frameworks for physical interpretation: the NC-frame, where it is manifest in the universe degrees of freedom, and in the C-frame, where it is manifest through theta-dependent terms in the Hamiltonian. As a result of our comparative analysis, we find that noncommutative geometry can remove singularities in the classical context for sufficiently large values of theta. Moreover, under special conditions, the classical noncommutative model can admit bouncing solutions characteristic of the commutative quantum FRW universe. In the quantum context, we find non-singular universe solutions containing bounces or being periodic in the quantum commutative model. When noncommutativity effects are turned on in the quantum scenario, they can introduce significant modifications that change the singular behavior of the universe solutions or that render them dynamical whenever they are static in the commutative case. The effects of noncommutativity are completely specified only when one of the frames for its realization is adopted as the physical one. Non-singular solutions in the NC-frame can be mapped into singular ones in the C-frame.Comment: explanations added, references include

Effective Potential and Spontaneous Symmetry Breaking in the Noncommutative phi^6 Model

We study the conditions for spontaneous symmetry breaking of the (2+1)-dimensional noncommutative phi^6 model in the small-theta limit. In this regime, considering the model as a cutoff theory, it is reasonable to assume translational invariance as a property of the vacuum state and study the conditions for spontaneous symmetry breaking by an effective potential analysis. An investigation of up to the two loop level reveals that noncommutative effects can modify drastically the shape of the effective potential. Under reasonable conditions, the nonplanar sector of the theory can become dominant and induce symmetry breaking for values of the mass and coupling constants not reached by the commutative counterpart.Comment: 11 pages, 2 figures, corrected to match with the PRD versio

Non-chemical alternative in rice storage: the use of refrigeration for insect control and quality maintenance of paddy rice

Trials were conducted to evaluate the potential effects of refrigeration in controlling insect infestations of Sitophilus zeamais and S. oryzae on stored rice. In the rice storage and processing industry use of aeration systems during winter and refrigeration units under summer conditions can provide a good solution to reduce paddy temperature for control of insects and maintenance of paddy quality; though it is restricted by costs of machinery and electric power. Trials were conducted in a rice mill in Portugal close to the Mondego Valley. A granary containing 140 t of paddy (variety Ripallo) was cooled using refrigerated aeration because during the trials ambient temperatures were too high for successful insect control by ambient air aeration. Sitophilus zeamais and S. oryzae adults reared on brown rice at 28°C and 68±3% r.h. were used as bioassays. Paddy stored in the granary was cooled to below 18ºC from 27 June 2008 to 19 September 2008. The mean ambient temperature during the total period of the trial varied from 12ºC to 27ºC. The moisture content of the paddy in the granary ranged from 12.1% to 13.9% during the same period of time. The total F1 of adult emergence population of S. zeamais and S. oryzae was counted after the experiments. The F1 adult from parent adults of S. zeamais was reduced up to 77%; the F1 adult from eggs of S. zeamais and S. oryzae were also reduced up to 71% and 45%, respectively, when compared with corresponding untreated controls. Refrigeration of the paddy allowed storage for almost three months at about 18ºC and caused delay in rice weevils development. As a consequence, this negated the necessity for fumigation. Although the energy consumed during refrigeration doubled the cost when compared with cooling using an ambient-air, aeration system during the cold season, refrigeration provided an environmentally sound and user-friendly treatment during warm months of the year. Keywords: Refrigeration, Sitophilus zeamais, Sitophilus oryzae, Paddy, Rice mill, Storag

Microenxertia e micropropagação para limpeza de patógenos em citros.

O Brasil ocupa posição de destaque no ramo da produção mundial de citros, sendo responsável por 30% e 59% das produções de laranja e suco concentrado. A citricultura tem sido de grande importância para o desenvolvimento socioeconômico, contribuindo com a geração direta e indireta de empregos e com a balança comercial do País