339 research outputs found
Antimicrobial activity of alcoholic extracts of medicinal plants against Phytopathogenic fungi.
Aims: This work aimed to evaluate the antimicrobial effects of 14 alcoholic extracts of medicinal plants on the mycelial growth of Colletotrichum gloeosporioides, Fusarium oxysporum f. sp. passiflorae, Fusarium solani and Rhizoctonia solani. Those are fungi that cause diseases in Passiflora edulis. Study Design: With the obtained data the mycelial growth rate index (MGRI) was calculated, afterwards the analysis of variance was performed and the means were compared by the Scott-Knott test at 5% probability. Place and Duration of Study: Plant Pathology Laboratory, Embrapa Eastern Amazon, BelĂ©m, ParĂĄ, Brazil, between May 2014 and April 2015. Methodology: The extracts were prepared with 1.0 g of powdered plant material and 10 mL of commercial ethyl alcohol 92.8Âș (0.1 g mL-1) under constant agitation in an orbital shaker at 200 rpm for 20 minutes. They were then kept in the refrigerator for 24 hours at rest. The extracts were centrifuged and filtered on Millipore membranes with 0.22 ”m porosity. The tests with the phytopathogenic fungi were carried out in vitro with the alcoholic extracts at 1% concentration. The experimental design was completely randomized with 15 treatments and 5 replicates. Results: All the extracts reduced the growth of the fungi C. gloeosporioides. The extracts the Eucalyptus angulosa, Lippia alba, Zingiber officinale, Cymbopagon citratus, Azadirachta indica, Plectranthus barbathus, Hibiscus sabdariffa, Aloe vera, Pedilanthus tithymaloides, Mansoa alliacea and Chenopodium ambrosioides reduced the mycelial growth of F. oxysporum f. sp. passiflorae. Only the extract of E. angulosa presented reduction in the growth of F. solani. Meanwhile the extracts of E. angulosa, Z. officinale, L. alba, M. alliacea and P. barbathus reduced the mycelial growth of R. solani. Conclusion: All extracts presented antimicrobial potential, being that the extract of E. angulosa reduced the mycelial growth of all the evaluated fungi
Characterization and variability of strains of Xanthomonas axonopodis pv. passiflorae from the state of ParĂĄ, Brazil.
Bacterial spot, caused by Xanthomonas axonopodis pv. passiflorae, is a disease that has limited the cultivation of passionfruit in various orchards in Brazil. The objective of this work is to characterize and evaluate the variability of 29 strains of X. axonopodis pv. passiflorae from different municipalities producing yellow passionfruit in the state of ParĂĄ. The characterization was performed by the biochemical methods of KOH solubility, oxidase and Bactray, and the molecular methods of Xapas-F, Xapas-Ri and Xapas-Ro primers. The variability was evaluated by pathogenicity test and RAPD (randomly amplified polymorphic DNA). The strains of X. axonopodis pv. passiflorae were Gram-negative and oxidase-negative, and tests with the Bactray kit showed no relation between the collection municipality and group composition. The Xapas-F/Ri/Ro primers were specific for the strains. The primers used amplified 118 polymorphic bands in the RAPD reactions and the highest genetic similarity was between the strains PA15 and PA16. As the pathogenicity test evidenced a pathogenic variability, the strains PA2.1, PA4.5, PA14, PA4.2, PA4.1, PA4.6, PA3.4 and PA4.3 present the highest severity values for the disease. The strains of X. axonopodis pv. passiflorae show characteristics typical of the species, and genetic and pathogenic variability among them
The rejuvenating power of the Buena Vista Social Club
26S proteasome, a major regulatory protease in eukaryotes, consists of a 20S proteolytic core particle (CP) capped by a 19S regulatory particle (RP). The 19S RP is divisible into base and lid sub-complexes. Even within the lid, subunits have been demarcated into two modules: module 1 (Rpn5, Rpn6, Rpn8, Rpn9 and Rpn11), which interacts with both CP and base sub-complexes and module 2 (Rpn3, Rpn7, Rpn12 and Rpn15) that is attached mainly to module 1. We now show that suppression of RPN11 expression halted lid assembly yet enabled the base and 20S CP to pre-assemble and form a base-CP. A key role for Regulatory particle non-ATPase 11 (Rpn11) in bridging lid module 1 and module 2 subunits together is inferred from observing defective proteasomes in rpn11âm1, a mutant expressing a truncated form of Rpn11 and displaying mitochondrial phenotypes. An incomplete lid made up of five module 1 subunits attached to base-CP was identified in proteasomes isolated from this mutant. Re-introducing the C-terminal portion of Rpn11 enabled recruitment of missing module 2 subunits. In vitro, module 1 was reconstituted stepwise, initiated by Rpn11âRpn8 heterodimerization. Upon recruitment of Rpn6, the module 1 intermediate was competent to lock into base-CP and reconstitute an incomplete 26S proteasome. Thus, base-CP can serve as a platform for gradual incorporation of lid, along a proteasome assembly pathway. Identification of proteasome intermediates and reconstitution of minimal functional units should clarify aspects of the inner workings of this machine and how multiple catalytic processes are synchronized within the 26S proteasome holoenzymes
A Complete Classification of Higher Derivative Gravity in 3D and Criticality in 4D
We study the condition that the theory is unitary and stable in
three-dimensional gravity with most general quadratic curvature,
Lorentz-Chern-Simons and cosmological terms. We provide the complete
classification of the unitary theories around flat Minkowski and (anti-)de
Sitter spacetimes. The analysis is performed by examining the quadratic
fluctuations around these classical vacua. We also discuss how to understand
critical condition for four-dimensional theories at the Lagrangian level.Comment: 20 pages, v2: minor corrections, refs. added, v3: logic modified, v4:
typos correcte
On the new massive gravity and AdS/CFT
Demanding the existence of a simple holographic -theorem, it is shown that
a general (parity preserving) theory of gravity in 2+1 dimensions involving
upto four derivative curvature invariants reduces to the new massive gravity
theory. We consider extending the theory including upto six derivative
curvature invariants. Black hole solutions are presented and consistency with
1+1 CFTs is checked. We present evidence that bulk unitarity is still in
conflict with a positive CFT central charge for generic choice of parameters.
However, for a special choice of parameters appearing in the four and six
derivative terms reduces the linearized equations to be two derivative, thereby
ameliorating the unitarity problem.Comment: 16 pages, 2 figures. v4: typo correcte
Note on New Massive Gravity in
In this note we study the properties of linearized gravitational excitations
in the new massive gravity theory in asymptotically spacetime and find
that there is also a critical point for the mass parameter at which massive
gravitons become massless as in topological massive gravity in .
However, at this critical point in the new massive gravity the energy of all
branches of highest weight gravitons vanish and the central charges also vanish
within the Brown-Henneaux boundary conditions. The new massive gravity in
asymptotically spacetime seems to be trivial at this critical point
under the Brown-Henneaux boundary conditions if the Brown-Henneaux boundary
conditions can be consistent with this theory. At this point, the boundary
conditions of log gravity may be preferred.Comment: v3 typos corrected, refs added, version to appear in JHE
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