Osmotic stress adaptation, compatible solutes accumulation and biocontrol efficacy of two potential biocontrol agents on Fusarium head blight in wheat

Fusarium head blight (FHB) caused by Gibberella zeae (anamorph = Fusarium graminearum) is a devastating disease that causes extensive yield and quality losses to wheat in humid and semi-humid regions of the world. Biological control has been demonstrated to be effective under laboratory conditions but a few biocontrol products have been effective under field conditions. The improvement in the physiological quality of biocontrol agents may improve survival under field conditions, and therefore, enhance biocontrol activity. Bacillus subtilis RC 218 and Brevibacillus sp. RC 263 were isolated from wheat anthers and showed significant effect on control of FHB under greenhouse assays. This study showed the effect of water availability measured as water activity (a_W) using a growth medium modified with NaCl, glycerol and glucose on: (i) osmotic stress tolerance, (ii) viability in modified liquid medium, (iii) quantitative intracellular accumulation of betaine and ectoine and (iv) the biocontrol efficacy of the physiologically improved agents. Viability of B. subtilis RC 218 in NaCl modified media was similar to the control. Brevibacillus sp. RC 263 showed a limited adaptation to growth in osmotic stress. Betaine was detected in high levels in modified cells but ectoine accumulation was similar to the control cells. Biocontrol activity was studied in greenhouse assays on wheat inoculated at anthesis period with F. graminearum RC 276. Treatments with modified bacteria reduced disease severity from 60% for the control to below 20%. The physiological improvement of biocontrol agents could be an effective strategy to enhance stress tolerance and biocontrol activity under fluctuating environmental conditions.     

Characterization of the phenol monooxygenase gene from Chromobacterium violaceum: Potential use for phenol biodegradation

In this work, the biodegradation mechanism of phenol and sub products (such as catechol and hydroquinone) in Chromobacterium violaceum was investigated by cloning and molecular characterization of a phenol monooxygenase gene in Escherichia coli. This gene (Cvmp) is very similar (74 and 59% of similarity and identity, respectively) to the ortholog from Ralstonia eutropha bacteria capable of utilizing phenol as the sole carbon source. The phenol biodegradation ability of E. coli recombinant strains was tested by cell-growth in a minimal medium containing phenol as the sole source of carbon and release of intermediary metabolites (catechol and hydroquinone). Interestingly, during the growth of these strains on phenol, catechol, and hydroquinone accumulated transiently in the medium. These metabolites were further analyzed by HPLC. These results indicated that phenol can be initially orto or para hydroxylated to produce cathecol or hydroquinone, respectively, followed by meta-cleavage of aromatic rings. To verify this information, the metabolites obtained from HPLC were submitted to LC/MS to confirm their chemical structure, thereby indicating that the recombinant strains utilize two different routes simultaneously, leading to different ring-fission substrates for the metabolism of phenol.     

Effect of environmental factors on tenuazonic acid production by Alternaria alternata on soybean-based media

Aims: To determine the effects of water activity (a_W; 0·995–0·90), temperature (5, 18, 25 and 30°C), time of incubation (7–35 days) and their interactions on tenuazonic acid (TA) production on 2% soybean‐based agar by two Alternaria alternata strains isolated from soybean in Argentina. Methods and Results: TA production by two isolates of A. alternata was examined under interacting conditions of a_W, temperature and time of incubation on 2% soybean‐based agar. Maximum TA production was obtained for both strains at 0·98 a_W, but at 30 and 25°C for the strains for RC 21and RC 39, respectively. The toxin concentration varied considerably depending on a_W, temperature, incubation time and strain interactions. TA was produced over the temperature range from 5 to 30°C and a_W range from 0·92 to 0·995, however at 5 and 18°C little TA was produced at a_W below 0·94. Contour maps were developed from these data to identify areas where conditions indicate a significant risk for TA accumulation. Conclusions: The optimum and marginal conditions for TA production by A. alternata on soybean‐based agar were identified. The results indicated that TA production by A. alternata is favoured by different temperatures in different strains. Significance and Impact of the Study: Data obtained provide very useful information for predicting the possible risk factors for TA contamination of soybean as the a_W and temperature range used in this study simulate those occurring during grain ripening. The knowledge of TA production under marginal or sub‐optimal temperature and a_W conditions for growth are relevant as improper storage conditions accompanied by elevated temperature and moisture content in the grain can favour further mycotoxin production and lead to reduction in grain quality.     

Minimum distance probability discriminant analysis for mixed variables

Minimum distance probability (MDP) is a robust discriminant algorithm based on a distance function. In this article, we generalize the use of MDP to the case of mixed (continuous and categorical) variables by means of the individual-score (IS) distance. This distance assumes an underlying parametric model and is based on the score transformation of the data. We have adapted it to the usual case of ignoring the distribution of the whole set of observed variables, but assuming that some knowledge about the marginal distributions is available. Finally, MDP with IS distance (IS-MDP) is compared with other discriminant methods (including those designed for mixed data) in several examples and simulations. IS-MDP is shown to be the most efficient method according the leave-one-out criterion.     

On the dynamics of a spherical scaffold in rotating bioreactors

We analyze the dynamics of a spherical scaffold in rotating bioreactors (or clinostats). The idealized clinostat environment consists of a purely rotational flow that is perpendicular to a gravitational field. We confirm through a detailed analytical study that lift effects considerably alter the position of the equilibrium point reached by the scaffolds in the (vertical) direction collinear to the gravitational field. This result holds for small particle and shear Reynolds numbers. Our analysis shows that the inertial lift effect is negligible in the horizontal direction. We show that for all rotations of practical interest, and for the range of particle Reynolds number smaller than unity, the vertical coordinate of the equilibrium point is strongly affected by consideration of lift effects. For light (heavy) particles, inclusion of lift in the formation forces the equilibrium position to be below (above) the horizontal plane that contains the axis of rotation. The equilibrium point for light particles is stable and therefore is observable experimentally. The equilibrium point for heavy particles is unstable. We also estimate the stress level applied to the scaffold and derive an algebraic expression that indicates that the stress level acting on the scaffold decreases with increasing shear Reynolds number.     

Synthesis and structure-affinity relationship investigations of 5-aminomethyl and 5-carbamoyl analogues of the antipsychotic sertindole. A new class of selective alpha1 adrenoceptor antagonists

A new class of selective alpha(1) adrenoceptor antagonists derived from the antipsychotic drug sertindole is described. The most potent and selective compound 1-(2-(4-[5-aminomethyl-1-(4-fluorophenyl)-1H-indol-3-yl]-1-piperidinyl)ethyl)-2-imidazolidinone (11) binds with 0.50 nM affinity for alpha(1) adrenergic receptors and with more than 44 times lower affinity for dopamine D(2),D(3), D(4) and serotonin 5-HT(1A), 5-HT(1B), 5-HT(2A) and 5-HT(2C) receptors. The molecular features providing high affinity for adrenergic alpha(1) receptors and high selectivity towards dopamine D(2) and serotonin 5-HT(2A) and 5-HT(2C) receptors are discussed.     

Psorophora columbiae and Psorophora toltecum (Diptera: Culicidae) Colombian populations cannot be differentiated by isoenzymes

Two populations of the mosquito Psorophora columbiae from the central Andean area of Colombia and one population of Ps. toltecum from the Atlantic coast of Colombia were analyzed for 11 isoenzyme markers. Psorophora columbiae and Ps. toltecum are two of the main vectors of Venezuelan equine encephalitis. We found no conspicuous genetic differences between the two species. The relatively high gene flow levels among these populations indicate that these are not two different species or that there has been recent divergence between these taxa. In addition, no global differential selection among the loci was detected, although the alpha-GDH locus showed significantly less genetic heterogeneity than the remaining loci, which could mean that homogenizing natural selection acts at this locus. No isolation by distance was detected among the populations, and a spatial population analysis showed opposite spatial trends among the 31 alleles analyzed. Multiregression analyses showed that both expected heterozygosity and the average number of alleles per locus were totally determined by three variables: altitude, temperature and size of the human population at the locality. Individually, the expected heterozygosity is more related to these three variables than to the average number of alleles.     

Reduction mammaplasty with the "owl" incision and no undermining

Reduction mammaplasty has traditionally been done using the Wise pattern of incision. Because of the box-like effect in breast shape, the lack of projection, and the long scars associated with the inverted T incision, two techniques have emerged as alternatives: the vertical reduction of Lassus/Lejour and the "round block" periareolar technique popularized by Benelli. Each of these techniques has its pros and cons.The "owl" incision combines the features of the large periareolar reduction (Benelli's) and the vertical reduction (Lassus/Lejour); the horizontal inframammary scar is either made very short or completely eliminated. Volume reduction is done through a heart-shaped parenchymal resection, leaving the nipple-areolar complex over a supero-central pedicle. Maintenance of the central parenchyma behind the nipple-areolar complex and mobilization of the vertical pillars toward the center of the breast give excellent projection and diminish the lateral fullness. Enlargement of the periareolar skin resection diminishes the length and pleating of the vertical scar; conversely, inclusion of the vertical component to the periareolar technique eliminates the pleating effect of the periareolar incision. The short horizontal excision eliminates any resultant "dog ears" in the new inframammary fold. Thus, the discrepancy in the length of scars is better distributed. There is no skin or parenchymal undermining, so drains are not needed. Excellent results are obtained immediately on the operating table, and large volumes of glandular resection and correction of severe ptosis can be accomplished without compromising vascularity of either the nipple-areolar complex or the skin flaps.Ninety-four patients in a 7-year period were operated upon using this technique. Seventy-two had bilateral reductions up to 1900 gm per breast, 12 had unilateral reduction for symmetry following breast reconstruction, and 10 were patients with severe ptosis. Complications were rare and of a minor nature. No conversion to free grafts was done, even in the larger resections. One case required minor revision under local anesthesia, one case required bilateral re-reduction, and another case required unilateral re-reduction for continued growth of breast tissue. Almost 90 percent of the patients underwent procedures as outpatients.The owl-type incision and the supero-central pedicle flap are elements of a reduction mammaplasty technique that provides excellent projection and shape with minimal visible scars. It takes advantage of the positive features of the periareolar and vertical reduction techniques and minimizes their negative features. The new design of parenchymal resection improves the vascularity of the residual flaps. Additionally, it may better preserve the sensation to the nipple-areolar complex and lactation is not compromised.     

Determination of N,N-dimethyltryptamine and beta-carboline alkaloids in human plasma following oral administration of Ayahuasca

Ayahuasca is a South American psychotropic beverage prepared from plants native to the Amazon River Basin. It combines the hallucinogenic agent and 5-HT(2A/2C) agonist N,N-dimethyltryptamine (DMT) with beta-carboline alkaloids showing monoamine oxidase-inhibiting properties. In the present paper, an analytical methodology for the plasma quantification of the four main alkaloids present in ayahuasca plus two major metabolites is described. DMT was extracted by liquid-liquid extraction with n-pentane and quantified by gas chromatography with nitrogen-phosphorus detection. Recovery was 74%, and precision and accuracy were better than 9.9%. The limit of quantification (LOQ) was 1.6 ng/ml. Harmine, harmaline, and tetrahydroharmine (THH), the three main beta-carbolines present in ayahuasca, and harmol and harmalol (O-demethylation metabolites of harmine and harmaline, respectively) were measured in plasma by means of high-performance liquid chromatography (HPLC) with fluorescence detection. Sample preparation was accomplished by solid-phase extraction, which facilitated the automation of the process. All five beta-carbolines were measured using a single detector by switching wavelengths. Separation of harmol and harmalol required only slight changes in the chromatographic conditions. Method validation demonstrated good recoveries, above 87%, and accuracy and precision better than 13.4%. The LOQ was 0.5 ng/ml for harmine, 0.3 ng/ml for harmaline, 1.0 ng/ml for THH, and 0.3 ng/ml for harmol and harmalol. Good linearity was observed in the concentration ranges evaluated for DMT (2.5-50 ng/ml) and the beta-carbolines (0.3-100 ng/ml). The gas chromatography and HPLC methods described allowed adequate characterization of the pharmacokinetics of the four main alkaloids present in ayahuasca, and also of two major beta-carboline metabolites not previously described in the literature.