Brachiaria decumbens supresses the initial growth of Coffea arabica

Brachiaria decumbens vem se tornando uma das plantas daninhas mais freqüentes na infestação de cafezais em formação, pois além de sua elevada agressividade e dificuldade de controle, está ocorrendo expansão das áreas cafeeiras para locais anteriormente ocupados por pastagens. Objetivou-se neste trabalho avaliar os efeitos desta planta daninha, em densidades crescentes, sobre o desenvolvimento inicial de mudas de café (Coffea arabica L. cv. Catuaí Amarelo). O experimento foi conduzido em condições semi-controladas, sem limitação de água. Uma muda de café foi transplantada em caixa de amianto com capacidade para 70 L, preenchida com terra coletada da camada arável de um Latossolo Vermelho. Os tratamentos constaram de diferentes densidades de transplante de capim-braquiária, a saber: 0, 4, 8, 12, 16, 20, 24, 36, 48 e 60 plantas m-2. O ensaio foi conduzido por um período experimental de 120 dias após o plantio (DAP). Todas as características analisadas foram afetadas negativamente pela interferência da planta daninha, mas as que se mostraram mais sensíveis a essa interferência foram à área foliar e a biomassa seca das folhas. Houve redução de 41,8% na área foliar do cafeeiro quando conviveu com o capim-braquiária a partir da densidade de 8 plantas m-2, chegando a 68,7% na densidade de 60 plantas m-2. Também a partir da densidade de 8 plantas m-2, a redução na biomassa seca das folhas em relação à testemunha foi de 41,4% e na densidade de 60 plantas m-2 chegou a 72,8%. Brachiaria decumbens, a partir da densidade de 8 plantas m-2, interfere negativamente sobre as mudas de café até os 120 DAP.

SOCIAL-CONTROL OF GROWTH IN FISH

This review concerns the phenomenon of heterogeneous growth (Het-G) in fish. Het-G is characterized by different growth rates between conspecifics. Although genetic determination on Het-G is recognized, grouping increases the difference in size between conspecifics. This review focuses on population factors and the mechanisms underlying the socially mediated Het-G are summarized and discussed. The aim of this paper is to arrive at a general statement explaining why grouping decreases mean growth and why it suppresses growth only in some individuals. The mechanisms described are: a) food competition, b) chemical factors released by conspecifics, and c) social stress. Social stress is analyzed in terms of the effect on appetite, digestive processes and metabolism. It is proposed that the predominant mechanism promoting socially mediated growth suppression is related to the social habit of the species. The biological significance of growth heterogeneity in fish is also discussed. Growth variability is suggested as an adaptative strategy to optimize survival of the population in a restricted space.

Influência de fatores bioclimáticos no desenvolvimento e produção do cafeeiro arábica e na qualidade dos grãos em Matão (SP)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Pkc1 acts through Zds1 and Gic1 to suppress growth and cell polarity defects of a yeast eIF5A mutant

eIF5A is a highly conserved putative eukaryotic translation initiation factor that has been implicated in translation initiation, nucleocytoplasmic transport, mRNA decay, and cell proliferation, but with no precise function assigned so far. We have previously shown that high-copy PKCI suppresses the phenotype of tif51A-1, a temperature-sensitive mutant of eIF5A in S. cerevisiae. Here, in an attempt to further understand how Pkc1 functionally interacts with eIF-5A, it was determined that PKCI suppression of tif51A-1 is independent of the cell integrity MAP kinase cascade. Furthermore, two new suppressor genes, ZDS1 and GIC1, were identified. We demonstrated that ZDS1 and ZDS2 are necessary for PKC1, but not for GIC1 suppression. Moreover, high-copy GIC1 also suppresses the growth defect of a PKCI mutant (stt1), suggesting the existence of a Pkc1-Zds1-Gic1 pathway. Consistent with the function of Gic1 in actin organization, the tif51A-1 strain shows an actin polarity defect that is partially recovered by overexpression of Pkc1 and Zds1 as well as Gic1. Additionally, PCL1 and BNI1, important regulators of yeast cell polarity, also suppress tif51A-1 temperature sensitiviiy Taken together, these data strongly Support the correlated involvement of Pkc1 and eIF5A in establishing actin polarity, which is essential for bud formation and G1/S transition in S. cerevisiae.

Interleukin-10 but not Transforming Growth Factor beta inhibits murine activated macrophages Paracoccidioides brasiliensis killing: Effect on H2O2 and NO production

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Fermi acceleration and its suppression in a time-dependent Lorentz gas

Some dynamical properties for a Lorentz gas were studied considering both static and time-dependent boundaries. For the static case, it was confirmed that the system has a chaotic component characterized with a positive Lyapunov exponent. For the time-dependent perturbation, the model was described using a four-dimensional nonlinear map. The behaviour of the average velocity is considered in two different situations: (i) non-dissipative and (ii) dissipative dynamics. Our results confirm that unlimited energy growth is observed for the non-dissipative case. However, and totally new for this model, when dissipation via inelastic collisions is introduced, the scenario changes and the unlimited energy growth is suppressed, thus leading to a phase transition from unlimited to limited energy growth. The behaviour of the average velocity is described using scaling arguments. (C) 2010 Elsevier B.V. All rights reserved.

Competition between suppression and production of Fermi acceleration

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Decay of energy and suppression of Fermi acceleration in a dissipative driven stadium-like billiard

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The effects of Diet and corticosteroid-induced immune suppression during infection by Haemonchus contortus in lambs

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Endophytic microorganisms isolated from coffee leaves, roots and branches as plant growth promoters and biocontrol agents of coffee leaf rust

Suppression of plant diseases and growth promotion due to the action of endophytic microorganisms has been demonstrated in several pathosystems. Experiments under controlled conditions involving 234 endophytic bacteria and fungi isolated from coffee leaves, roots and branches were conducted with the objective of evaluating the germination inhibition of Hemileia vastatrix urediniospores, the control of coffee leaf rust development in tests with leaf discs and on plastic bags seedling, and to promote growth of coffee seedlings. None of the fungal isolates induced plant growth or reduced disease severity. The bacterial isolates (identified by the fatty acids profile analysis) 85G (Escherichia fergusonii), 161G, 163G, 160G, 150G (Acinetobacter calcoaceticus) and 109G (Salmonella enterica) increased plant growth, the maximum being induced by 85G. This isolate produced in vitro phosphatase and indol acetic acid. In assay to control rust on coffee leaf disc, nine bacterial isolates, 64R, 137G, 3F (Brevibacillus choshinensis), 14F (Salmonella enterica), 36F (Pectobacterium carotovorum), 109G (Bacillus megaterium), 115G (Microbacterium testaceum), 116G and 119G (Cedecea davisae) significantly reduced disease severity, when applied 72 or 24h before challenging with the pathogen. In seedling tests most disease severity reduction was achieved by the isolates 109G and 119G. There was no correspondence between the organisms that promoted seedling growth and those that reduced rust severity on seedlings or leaf discs.