Biologia molecular aplicada aos recursos genéticos.

Este trabalho tem como objetivo descrever algumas das metodologias de biologia molecular utilizadas no Laboratório de Genética da Embrapa Amazônia Oriental (LABGEN) e Laboratório de Fitopatologia, visando à identificação, classificação e conservação de recursos genéticos, levando-se em consideração as peculiaridades observadas. É uma abordagem prática, sendo que os protocolos apresentados são passíveis de alteração pelo usuário, conforme as particularidades do seu trabalho e necessitam do máximo de critério para a execução

Genotypic variability and antifungal susceptibility of Candida spp. isolated from hospital surfaces and hands of healthcare professionals

Objectives Candida spp. are responsible for 9095% of hematogenous fungal infections. In Brazil and Latin America, C. albicans is the most common specie, followed by C. parapsilosis and C. tropicalis. Infections caused by Candida spp. may have their origin in exogenous sources, transmitted to patients via contaminated infusions, biomedical devices or even by the hands of the hospital staff members. Molecular biology techniques such as Randomly Amplified Polymorphic DNA (RAPD) can show that the strains found in anatomical sites or abi- otic surfaces have the same pattern genome.Moreover, in the last decades it has been observed increasing the number of yeasts isolated from hospital environment resistant to antifungals. Thus, the aim of this study was to determine the susceptibility to antifungals and intraspecies similarity among isolates of different hospital surfaces and hands of healthcare professionals. Methods The study was conducted with 25 isolates of Candida spp.: 5 strains of C. albicans and 5 strains of C. parapsilosis isolated from hospital surfaces. 5 strains of C. albicans, 5 strains of C. parapsilosis and 5 strains of C. tropicalis isolated from hands of healthcare professionals. Professionals and surfaces belonged to intensive care units. The minimal inhibitory concentration (MIC) was determined to voriconazole (VOR), fluconazole (FLZ), amphotericin B (AMB) and micafungin (MFG) according to M27-A3 of the Clinical and Labora- tory Standards Institute (CLSI). To determine the intra-species similarity, 3 primers were used: P4 (50 -AAGAGCCCGT-30 ), OPA-18 (50AGCTGACCGT30) and OPE-18 (50GGACTGCAGA 30). RAPD pro- files were analyzed using BioNumerics software version 4.6. The study was approved by the Ethics in research involving human subjects, CAAE 0448.0.093.000-11 protocol. Results In relation to susceptibility testing (Table 1), it is important to highlight that C. parapsilosis showed 80% of MFG resistance. C. albicans and C. tropicalis showed reduced susceptibility to VOR, and resistence of the AMB was observed for C. albicans (20%). All amplifi- cations revealed distinct polymorphic bands. Genetic distances between each of the isolates were calculated and cluster analysis was used to generate a dendrogram showing relationships between them. The analysis of all primers showed similarity greater than 80% between strains of hands and hospital surfaces for intraspecies. Conclusion Our work shows that, healthy people and hospital surfaces may be colonized by different species yeast. Furthermore, the strains studied had relative resistance to antifungal drugs most frequently used in clinical practice. Finally, there was a high similarity between samples from hands (hospital staff members) and surfaces, providing an infection risk to susceptible individuals. Healthy people working in hospitals can carry yeasts on their hands with the same potential virulence, and which therefore offer the same risk of infection. This information should be considered when preventive measures are established. Attention to the colonization of hands and surfaces should not be restricted to high-risk units such as NICUs, but should also include other sections of hospitals

Spin Diffusion in Classical Heisenberg Magnets with Uniform, Alternating, and Random Exchange

We have carried out an extensive simulation study for the spin autocorrelation function at T=∞ of the one‐dimensional classical Heisenberg model with four different types of isotropic bilinear nearest‐neighbor coupling: uniform exchange, alternating exchange, and two kinds of random exchange. For the long‐time tails of all but one case, the simulation data seem incompatible with the simple ∼t −1/2 leading term predicted by spin diffusion phenomenology

Percolation Threshold, Fisher Exponent, and Shortest Path Exponent for 4 and 5 Dimensions

We develop a method of constructing percolation clusters that allows us to build very large clusters using very little computer memory by limiting the maximum number of sites for which we maintain state information to a number of the order of the number of sites in the largest chemical shell of the cluster being created. The memory required to grow a cluster of mass s is of the order of $s^\theta$ bytes where $\theta$ ranges from 0.4 for 2-dimensional lattices to 0.5 for 6- (or higher)-dimensional lattices. We use this method to estimate $d_{\scriptsize min}$, the exponent relating the minimum path $\ell$ to the Euclidean distance r, for 4D and 5D hypercubic lattices. Analyzing both site and bond percolation, we find $d_{\scriptsize min}=1.607\pm 0.005$ (4D) and $d_{\scriptsize min}=1.812\pm 0.006$ (5D). In order to determine $d_{\scriptsize min}$ to high precision, and without bias, it was necessary to first find precise values for the percolation threshold, $p_c$: $p_c=0.196889\pm 0.000003$ (4D) and $p_c=0.14081\pm 0.00001$ (5D) for site and $p_c=0.160130\pm 0.000003$ (4D) and $p_c=0.118174\pm 0.000004$ (5D) for bond percolation. We also calculate the Fisher exponent, $\tau$, determined in the course of calculating the values of $p_c$: $\tau=2.313\pm 0.003$ (4D) and $\tau=2.412\pm 0.004$ (5D)

Assessment of in vitro biofilm formation and antifungal susceptibility of Candida albicans isolates from vulvovaginal candidiasis

Objectives Vulvovaginal candidiasis (VVC) is an inflammation of the genital mucosa, which mainly affects the vulva and vagina. Candida spp. are considered commensal fungus, however, when there is imbalance in the microbiota or the host immune system is compromised, these can become pathogenic. C. albicans is responsible for most cases of VVC and is able of expressing mechanisms which allow the colonization or infection in the host. These factors related yeasts, including the growth of strains resistant to antifungal agents and virulence attributes (such as biofilm formation) are important in the development of VVC. In this sense, the objective of this study was to evaluate the in vitro biofilm formation and susceptibility to antifungal of C. albicans isolates from patients with vulvovaginal candidiasis. Methods For the study were analyzed 30 clinical isolates of Candida albicans. The clinical isolates were separated in groups of 10 samples of the according to symptoms presented by the patients: asymptomatic (AS), vulvovaginal candidiasis (VVC) and recurrent vulvo- vaginal candidiasis (RVVC). For all isolates were analyzed biofilm formation and minimal inhibitory concentration (MIC) for fluconazole and nystatin. The MIC was performed according to M27-A3 protocol of the Clinical Laboratory Standards Institute. Biofilm forming ability was assessed through quantification of total biomass by crystal violet (CV) staining, performed on 96-well microplates containing a cellular suspension of 1 9 107 cells ml1 and incubated for 24 h at 37°C. Results Antifungal susceptibility testing is showed in table 1. The isolates were tested to the two antifungals. The MIC raging from 0.125 to 2 lg ml1 for fluconazole and 1 to 4 lg ml1 to nystatin. The figure 1 show the quantification of the total biomass. It was evident that all the C. albicans isolates were able to form biofilm, although differences occurred depending on the isolated and consequently the group. Importantly it was noted that, in general, VVC and RVVC groups had similar capacity biofilm formation. On the other hand, these groups had less total biomass (average Abs = 1,091 ` 0.88) compared with AS group (average Abs = 1,521 ` 1.32). Conclusion Although all the samples analyzed are sensitive to anti- fungals tested research of resistant strains is relevant, since recurrences are related to cases of VVC. Nystatin and fluconazole were effective in small concentrations for the isolates analysed. All samples were able to form biofilm and the average of the group of asymptomatic patients greater than the others. Thus, the capacity to form- ing biofilm is an important virulence factor in the persistence of microorganisms in infectious processes and represent an increase in resistance to antifungal and host defense

Magnetic relaxation of exchange biased (Pt/Co) multilayers studied by time-resolved Kerr microscopy

Magnetization relaxation of exchange biased (Pt/Co)5/Pt/IrMn multilayers with perpendicular anisotropy was investigated by time-resolved Kerr microscopy. Magnetization reversal occurs by nucleation and domain wall propagation for both descending and ascending applied fields, but a much larger nucleation density is observed for the descending branch, where the field is applied antiparallel to the exchange bias field direction. These results can be explained by taking into account the presence of local inhomogeneities of the exchange bias field.Comment: To appear in Physical Review B (October 2005

Intermediate temperature dynamics of one-dimensional Heisenberg antiferromagnets

We present a general theory for the intermediate temperature (T) properties of Heisenberg antiferromagnets of spin-S ions on p-leg ladders, valid for 2Sp even or odd. Following an earlier proposal for 2Sp even (Damle and Sachdev, cond-mat/9711014), we argue that an integrable, classical, continuum model of a fixed-length, 3-vector applies over an intermediate temperature range; this range becomes very wide for moderate and large values of 2Sp. The coupling constants of the effective model are known exactly in terms of the energy gap above the ground state (for 2Sp even) or a crossover scale (for 2Sp odd). Analytic and numeric results for dynamic and transport properties are obtained, including some exact results for the spin-wave damping. Numerous quantitative predictions for neutron scattering and NMR experiments are made. A general discussion on the nature of T>0 transport in integrable systems is also presented: an exact solution of a toy model proves that diffusion can exist in integrable systems, provided proper care is taken in approaching the thermodynamic limit.Comment: 38 pages, including 12 figure

Acibenzolar-s-metil, oxicloreto de cobre e fertilizantes foliares no controle da mancha bacteriana do maracujazeiro.

Edição dos resumos do 44º Congresso Brasileiro de Fitopatologia, 2011, Bento Gonçalves. Resumo 1172

New Dynamic Monte Carlo Renormalization Group Method

The dynamical critical exponent of the two-dimensional spin-flip Ising model is evaluated by a Monte Carlo renormalization group method involving a transformation in time. The results agree very well with a finite-size scaling analysis performed on the same data. The value of $z = 2.13 \pm 0.01$ is obtained, which is consistent with most recent estimates