Antimicrobial activity of Rheedia brasiliensis and 7-epiclusianone against Streptococcus mutans

This in vitro study evaluated the antimicrobial activity of extracts obtained from Rheedia brasiliensis fruit (bacupari) and its bioactive compound against Streptococcus mutans. Hexane, ethyl-acetate and ethanolic extracts obtained (concentrations ranging from 6.25 to 800 mu g/ml) were tested against S. mutans UA159 through MIC/MBC assays. S. mutans 5-days-old biofilms were treated with the active extracts (100 x MIC) for 0, 1, 2, 3 and 4 h (time-kill) and plated for colony counting (CFU/ml). Active extracts were submitted to exploratory chemical analyses so as to isolate and identify the bioactive compound using spectroscopic methods. The bioactive compound (concentrations ranging from 0.625 to 80 mu g/ml) was then tested through MIC/MBC assays. Peel and seed hexane extracts showed antimicrobial activity against planktonic cells at low concentrations and were thus selected for the time kill test. These hexane extracts reduced S. mutans biofilm viability after 4 h, certifying of the bioactive compound presence. The bioactive compound identified was the polyprenylated benzophenone 7-epiclusianone, which showed a good antimicrobial activity at low concentrations (MIC: 1.25-2.5 mu g/ml; MBC: 10-20 mu g/ml). The results indicated that 7-epiclusianone may be used as a new agent to control S. mutans biofilms; however, more studies are needed to further elucidate the mechanisms of action and the anticariogenic potential of such compound found in R. brasiliensis. (C) 2008 Elsevier GmbH. All rights reserved.

An integrated molecular map of yellow passion fruit based on simultaneous maximum-likelihood estimation of linkage and linkage phases

The development of genetic maps for auto-incompatible species, such as the yellow passion fruit (Passiflora edulis Sims f.flavicarpa Deg.) is restricted due to the unfeasibility of obtaining traditional mapping populations based on inbred lines. For this reason, yellow passion fruit linkage maps were generally constructed using a strategy known as two-way pseudo-testeross, based on monoparental dominant markers segregating in a 1:1 fashion. Due to the lack of information from these markers in one of the parents, two individual (parental) maps were obtained. However, integration of these maps is essential, and biparental markers can be used for such an operation. The objective of our study was to construct an integrated molecular map for a full-sib population of yellow passion fruit combining different loci configuration generated from amplified fragment length polymorphisms (AFLPs) and microsatellite markers and using a novel approach based on simultaneous maximum-likelihood estimation of linkage and linkage phases, specially designed for outcrossing species. Of the total number of loci, approximate to 76%, 21%, 0.7%, and 2.3% did segregate in 1:1, 3:1, 1:2:1, and 1:1:1:1 ratios, respectively. Ten linkage groups (LGs) were established with a logarithm of the odds (LOD) score >= 5.0 assuming a recombination fraction : <= 0.35. On average, 24 markers were assigned per LG, representing a total map length of 1687 cM, with a marker density of 6.9 cM. No markers were placed as accessories on the map as was done with previously constructed individual maps.

Endophytic population of Pantoea agglomerans in citrus plants and development of a cloning vector for endophytes

Harmless bacteria inhabiting inner plant tissues are termed endophytes. Population fluctuations in the endophytic bacterium Pantoea agglomerans associated with two species of field cultured citrus plants were monitored over a two-year period. The results demonstrated that populations of P. agglomerans fluctuated in Citrus reticulata but not C. sinensis. A cryptic plasmid pPA3.0 (2.9 kb) was identified in 35 out of 44 endophytic isolates of P. agglomerans and was subsequently sequenced. The origins of replication were identified and nine out of 18 open reading frames (ORFs) revealed homology with described proteins. Notably, two ORFs were related to cellular transport systems and plasmid maintenance. Plasmid pPA3.0 was cloned and the gfp gene inserted to generate the pPAGFP vector. The vector was introduced into P. agglomerans isolates and revealed stability was dependent on the isolate genotype, ninety-percent stability values were reached after 60 hours of bacterial cultivation in most evaluated isolates. In order to definitively establish P. agglomerans as an endophyte, the non-transformed bacterium was reintroduced into in vitro cultivated seedlings and the density of inner tissue colonization in inoculated plants was estimated by bacterium re-isolation, while the tissue niches preferred by the bacterium were investigated by scanning electronic microscopy (SEM). Cells from P. agglomerans (strain ARB18) at similar densities were re-isolated from roots, stems and leaves and colonization of parenchyma and xylem tissues were observed. Data suggested that P. agglomerans is a ubiquitous citrus endophyte harboring cryptic plasmids. These characteristics suggest the potential to use the bacterium as a vehicle to introduce new genes in host plants via endophytic bacterial transformation.

The development and production of leaves and tillers by Marandu palisadegrass fertilised with nitrogen and sulphur

The effects of combined nitrogen and sulphur fertilisation on the dynamics of leaf and tiller appearance in Marandu palisadegrass (Brachiaria brizantha cv. Marandu) and its impact on dry matter production were evaluated in a greenhouse study. Grass seedlings were grown in pots filled with a soil classified as an Entisol and were harvested after 43 days, a further 35 days and finally after 48 more days. Five rates of N (0, 100, 200, 300 and 400 mg/dm(3)) and 5 rates of S (0, 10, 20, 30 and 40 mg/dm(3)) were tested in an incomplete factorial design with 4 replications. Leaf and tiller development were monitored every 3 days by counting the appearance of recently expanded leaves and new basal tillers. The phyllochron and thermal time between appearance of tillers decreased as N and S fertiliser levels increased to about 300 and 25 mg/dm(3), respectively, then tended to increase. In contrast, leaf and tiller appearance rates increased with the supply of these nutrients to similar levels, then tended to decline. Leaf and tiller production and dry matter yields were affected by both N and S levels, with the role of S increasing as the growth phases increased.

Tree-ring formation, radial increment periodicity, and phenology of tree species from a seasonal semi-deciduous forest in southeast Brazil

Many tropical tree species produce growth rings in response to seasonal environmental factors that influence the activity of the vascular cambium. We applied the following methods to analyze the annual nature of treering formation of 24 tree species from a seasonal semi-deciduous forest of southeast Brazil: describing wood anatomy and phenology, counting tree rings after cambium markings, and using permanent dendrometer bands. After 7 years of systematic observations and measurements, we found the following: the trees lost their leaves during the dry season and grew new leaves at the end of the same season; trunk increment dynamics corresponded to seasonal changes in precipitation, with higher increment (active period) during the rainy season (October-April) and lower increment (dormant period) during the dry season (May-September); the number of tree rings formed after injuries to the cambium coincided with the number of years since the extraction of the wood samples. As a result of these observations, it was concluded that most study trees formed one growth ring per year. This suggests that tree species from the seasonal semi-deciduous forests of Brazil have an annual cycle of wood formation. Therefore, these trees have potential for use in future studies of tree age and radial growth rates, as well as to infer ecological and regional climatic conditions. These future studies can provide important information for the management and conservation of these endangered forests.

Prevalence and counts of Salmonella spp. in minimally processed vegetables in Sao Paulo, Brazil

Minimally processed vegetables (MPV) may be important vehicles of Salmonella spp. and cause disease. This study aimed at detecting and enumerating Salmonella spp. in MPV marketed in the city of Sao Paulo, Brazil. A total of 512 samples of MPV packages collected in retail stores were tested for Salmonella spp. and total coliforms and Escherichia coil as indication of the hygienic status. Salmonella spp. was detected in four samples, two using the detection method and two using the counting method, where the results were 8.8 x 10(2) CFU/g and 2.4 x 10(2) CFU/g. The serovars were Salmonella Typhimurium (three samples) and Salmonella enterica subsp. enterica O:47:z4,z23:- (one sample). Fourteen samples (2.7%) presented counts of E. coli above the maximum limit established by the Brazilian regulation for MPV (10(2) CFU/g). Therefore, tightened surveillance and effective intervention strategies are necessary in order to address consumers and governments concerns on safety of MPV. (C) 2011 Elsevier Ltd. All rights reserved.

The effect of the dibenzylbutyrolactolic lignan (-)-cubebin on doxorubicin mutagenicity and recombinogenicity in wing somatic cells of Drosophila melanogaster

The dibenzylbutyrolactolic lignan (-)-cubebin was isolated from dry seeds of Piper cubeba L (Piperaceae). (-)-Cubebin possesses anti-inflammatory, analgesic and antimicrobial activities. Doxorubicin (DXR) is a topoisomerase-interactive agent that may induce single- and double-strand breaks, intercalate into the DNA and generate oxygen free radicals. Here, we examine the mutagenicity and recombinogenicity of different concentrations of (-)-cubebin alone or in combination with DXR using standard (ST) and high bioactivation (HB) crosses of the wing Somatic Mutation And Recombination Test in Drosophila melanogaster. The results from both crosses were rather similar. (-)-Cubebin alone did not induce mutation or recombination. At lower concentrations, (-)-cubebin statistically reduced the frequencies of DXR-induced mutant spots. At higher concentrations, however, (-)-cubebin was found to potentiate the effects of DXR, leading to either an increase in the production of mutant spots or a reduction, due to toxicity. These results suggest that depending on the concentration, (-)-cubebin may interact with the enzymatic system that catalyzes the metabolic detoxification of DXR, inhibiting the activity of mitochondria! complex 1 and thereby scavenging free radicals. Recombination was found to be the major effect of the treatments with DXR alone. The combined treatments reduced DXR mutagenicity but did not affect DXR recombinogenicity. (C) 2011 Elsevier Ltd. All rights reserved.

Development of a physical and genetic map of the virulent Wolbachia strain wMelPop

We report here the construction of a physical and genetic map of the virulent Wolbachia strain, wMelPop. This map was determined by ordering 28 chromosome fragments that resulted from digestion with the restriction endonucleases FseI, ApaI, SmaI, and AscI and were resolved by pulsed-field gel electrophoresis. Southern hybridization was done with 53 Wolbachia-specific genes as probes in order to determine the relative positions of these restriction fragments and use them to serve as markers. Comparison of the resulting map with the whole genome sequence of the closely related benign Wolbachia strain, wMel, shows that the two genomes are largely conserved in gene organization with the exception of a single inversion in the chromosome.

Isolation of genotype- and chromosome-specific DNA markers in a biotype of Colletotrichum gloeosporioides using random amplified polymorphic DNA analysis

Genetic markers that distinguish fungal genotypes are important tools for genetic analysis of heterokaryosis and parasexual recombination in fungi. Random amplified polymorphic DNA (RAPD) markers that distinguish two races of biotype B of Colletotrichum gloeosporioides infecting the legume Stylosanthes guianensis were sought. Eighty-five arbitrary oligonucleotide primers were used to generate 895 RAPD bands but only two bands were found to be specifically amplified from DNA of the race 3 isolate. These two RAPD bands were used as DNA probes and hybridised only to DNA of the race 3 isolate. Both RAPD bands hybridised to a dispensable 1.2 Mb chromosome of the race 3 isolate. No other genotype-specific chromosomes or DNA sequences were identified in either the race 2 or race 3 isolates. The RAPD markers hybridised to a 2 Mb chromosome in all races of the genetically distinct biotype A pathogen which infects other species of Stylosanthes as well as S. guianensis. The experiments indicate that RAPD analysis is a potentially useful tool for obtaining genotype-and chromosome-specific DNA probes in closely related isolates of one biotype of this fungal pathogen.

Effects of stimulus modality and task condition on blink startle modification and on electrodermal responses

Participants in Experiments 1 and 2 performed a discrimination and counting task to assess the effect of lead stimulus modality on attentional modification of the acoustic startle reflex. Modality of the discrimination stimuli was changed across subjects. Electrodermal responses were larger during task-relevant stimuli than during task-irrelevant stimuli in all conditions. Larger blink magnitude facilitation was found during auditory and visual task-relevant stimuli, but not for tactile stimuli. Experiment 3 used acoustic, visual, and tactile conditioned stimuli (CSs) in differential conditioning with an aversive unconditioned stimulus (US). Startle magnitude facilitation and electrodermal responses were larger during a CS that preceded the US than during a CS that was presented alone regardless of lead stimulus modality. Although not unequivocal, the present data pose problems for attentional accounts of blink modification that emphasize the importance of lead stimulus modality.

Arterial heparan sulfate proteoglycans inhibit vascular smooth muscle cell proliferation and phenotype change in vitro and neointimal formation in vivo

Purpose: The aim of this study was to determine whether heparan sulfate proteoglycans (HSPGs) from the normal arterial wall inhibit neointimal formation after injury in vivo and smooth muscle cell (SMC) phenotype change and proliferation in vitro. Methods: Arterial HSPGs were extracted from rabbit aortae and separated by anion-exchange chromatography. The effect of HSPGs, applied in a periadventitial gel, on neointimal formation was assessed 14 days after balloon catheter injury of rabbit carotid arteries. Their effect on SMC phenotype and proliferation was measured by point-counting morphometry of the cytoplasmic volume fraction of myofilaments (Vvmyo) and H-3-thymidine incorporation in SMCs in culture. Results: Arterial HSPGs (680 mu g) reduced neointimal formation by 35% at 14 days after injury (P =.029), whereas 2000 mu g of the low-molecular-weight heparin Enoxaparin was ineffective. HSPGs at 34 mu g/mL maintained subconfluent primary cultured SMCs with the same high Vvmyo (52.1% +/- 13.8%) after 5 days in culture as did cells freshly isolated from the arterial wall (52.1% +/- 15.1%). In contrast, 100 mu g/mL Enoxaparin was ineffective in preventing phenotypic change over this time period (Vvmyo 38.9% +/- 14.6%, controls 35.9% +/- 12.8%). HSPGs also inhibited 3H-thymidine incorporation into primary cultured SMCs with an ID50 value of 0.4 mu g/mL compared with a value of 14 mu g/ml; for Enoxaparin (P

Familial hyperaldosteronism type II: Description of a large kindred and exclusion of the aldosterone synthase (CYP11B2) gene

Familial hyperaldosteronism type II (FH-II) is characterized by autosomal dominant inheritance and hypersecretion of aldosterone due to adrenocortical hyperplasia or an aldosterone-producing adenoma; unlike FH type I (FH-I), hyperaldosteronism in FH-II is not suppressible by dexamethasone. Of a total of 17 FH-II families with 44 affected members, we studied a large kindred with 7 affected members that was informative for linkage analysis. Family members were screened with the aldosterone/PRA ratio test; patients with aldosterone/PRA ratio greater than 25 underwent fludrocortisone/salt suppression testing for confirmation of autonomous aldosterone secretion. Postural testing, adrenal gland imaging, and adrenal venous sampling were also performed. Individuals affected by FH-II demonstrated lack of suppression of plasma A levels after 4 days of dexamethasone treatment (0.5 mg every 6 h). All patients had neg ative genetic testing for the defect associated with FH-I, the CYP11B1/CYP11B2 hybrid gene. Genetic linkage was then examined between FH-II and aldosterone synthase (the CYP11B2 gene) on chromosome 8q. A polyadenylase repeat within the 5'-region of the CYP11B2 gene and 9 other markers covering an approximately 80-centimorgan area on chromosome 8q21-8qtel were genotyped and analyzed for linkage. Two-point logarithm of odds scores were negative and ranged from -12.6 for the CYP11B2 polymorphic marker to -0.98 for the D8S527 marker at a recombination distance (theta) of 0. Multipoint logarithm of odds score analysis confirmed the exclusion of the chromosome 8q21-8qtel area as a region harboring the candidate gene for FH-II in this family. We conclude that FH-II shares autosomal dominant inheritance and hyperaldosteronism with FH-I, but, as demonstrated by the large kindred investigated in this report, it is clinically and genetically distinct. Linkage analysis demonstrated that the CYP11B2 gene is not responsible for FH-II in this family; furthermore, chromosome 8q21-8qtel most likely does not harbor the genetic defect in this kindred.

Phase diagram for a class of spin-1/2 Heisenberg models interpolating between the square-lattice, the triangular-lattice, and the linear-chain limits

We study the spin-1/2 Heisenberg models on an anisotropic two-dimensional lattice which interpolates between the square lattice at one end, a set of decoupled spin chains on the other end, and the triangular-lattice Heisenberg model in between. By series expansions around two different dimer ground states and around various commensurate and incommensurate magnetically ordered states, we establish the phase diagram for this model of a frustrated antiferromagnet. We find a particularly rich phase diagram due to the interplay of magnetic frustration, quantum fluctuations, and varying dimensionality. There is a large region of the usual two-sublattice Neel phase, a three-sublattice phase for the triangular-lattice model, a region of incommensurate magnetic order around the triangular-lattice model, and regions in parameter space where there is no magnetic order. We find that the incommensurate ordering wave vector is in general altered from its classical value by quantum fluctuations. The regime of weakly coupled chains is particularly interesting and appears to be nearly critical. [S0163-1829(99)10421-1].

Context-free and context-sensitive dynamics in recurrent neural networks

Continuous-valued recurrent neural networks can learn mechanisms for processing context-free languages. The dynamics of such networks is usually based on damped oscillation around fixed points in state space and requires that the dynamical components are arranged in certain ways. It is shown that qualitatively similar dynamics with similar constraints hold for a(n)b(n)c(n), a context-sensitive language. The additional difficulty with a(n)b(n)c(n), compared with the context-free language a(n)b(n), consists of 'counting up' and 'counting down' letters simultaneously. The network solution is to oscillate in two principal dimensions, one for counting up and one for counting down. This study focuses on the dynamics employed by the sequential cascaded network, in contrast to the simple recurrent network, and the use of backpropagation through time. Found solutions generalize well beyond training data, however, learning is not reliable. The contribution of this study lies in demonstrating how the dynamics in recurrent neural networks that process context-free languages can also be employed in processing some context-sensitive languages (traditionally thought of as requiring additional computation resources). This continuity of mechanism between language classes contributes to our understanding of neural networks in modelling language learning and processing.

Determination of T1pH relaxation rates in charred and uncharred wood and consequences for NMR quantitation

The performance of three different techniques for determining proton rotating frame relaxation rates (T1pH) in charred and uncharred woods is compared. The variable contact time (VCT) experiment is shown to over-estimate T1pH, particularly for the charred samples, due to the presence of slowly cross-polarizing C-13 nuclei. The variable spin (VSL) or delayed contact experiment is shown to overcome these problems; however, care is needed in the analysis to ensure rapidly relaxing components are not overlooked. T1pH is shown to be non-uniform for both charred and uncharred wood samples; a rapidly relaxing component (T1pH = 0.46-1.07 ms) and a slowly relaxing component (T1pH = 3.58-7.49) is detected in each sample. T1pH for each component generally decreases with heating temperature (degree of charring) and the proportion of rapidly relaxing component increases. Direct T1pH determination (via H-1 detection) shows that all samples contain an even faster relaxing component (0.09-0.24 ms) that is virtually undetectable by the indirect (VCT and VSL) techniques. A new method for correcting for T1pH signal losses in spin counting experiments is developed to deal with the rapidly relaxing component detected in the VSL experiment. Implementation of this correction increased the proportion of potential C-13 CPMAS NMR signal that can be accounted for by up to 50% for the charred samples. An even greater proportion of potential signal can be accounted for if the very rapidly relaxing component detected in the direct T1pH determination is included; however, it must be kept in mind that this experiment also detects H-1 pools which may not be involved in H-1-C-13 cross-polarization. (C) 2002 Elsevier Science (USA).