Factors of the shape change of human erythrocytes induced with lidocaine

We studied the molecular mechanism of the shape change of erythrocytes with a local anesthetic, lidocaine. The shape of human erythrocytes changed from discocytes to stomatocytes in the presence of lidocaine when ATP was present. But, the shape of resealed cells which were prepared with 10 mM Tris-HCl buffer (pH 7.4) containing 2 mM ATP-MgCl2 and various substances was not changed from discocytes to stomatocytes with lidocaine. When intact cells and resealed cells which were prepared with various concentrations of Tris-HCl buffer (pH 7.4) were incubated with various concentrations of lidocaine and their membrane proteins were analyzed by SDS-PAGE, the densities of bands 62K, 28K and 22K depended on lidocaine concentration: in particular, that of band 28K changed remarkably. These membranous 62K-, 28K- and 22K-proteins agreed with cytoplasmic 62K-, 28K- and 22K-proteins in molecular weight. We propose that not only ATP but also the 62K-, 28K- and 22K-proteins in the cytoplasm are concerned with the shape change of human erythrocytes induced with lidocaine.     

La hidrofobicidad de la superficie celular como indicador de otros factores de virulencia en Candida albicans

ObjectiveTo evaluate virulence factors involved in the adhesion process, such as cell surface hydrophobicity (CSH), adherence to plastic capacity, adherence capacity to buccal epithelial cells (BEC), and biofilm formation, in 17 strains of C. albicans isolated from bronchial aspirates of critically ill patients.MethodThe CSH of the strains of C. albicans was determined using the MATH method, a microbial adhesion to hydrocarbons test. The study of adherence to plastic was performed in microtitre plates in accordance with Christensen's technique. Biofilm formation was studied in polystyrene microtitre plates, according to the method of Ramage. Adherence to BEC was evaluated by quantifying the percentage of adhered yeasts to cells.ResultsAll the strains studied showed factors directly involved in adhesion, with variability in the degree of expression among them. Medium-high levels of CSH were found in 52.9% of the strains. The percentage of strains with high values in adherence to plastic was 35.3%. The most hydrophobic strains were the most adherent to plastic, with a correlation coefficient of 0.76. Of the 12 biofilm-producing strains, 6 were high producers. These strains had also high levels of CSH and adherence to plastic, with significant results. All the strains studied adhered to BEC, with results ranging widely from 45 to 157 yeasts/100 BEC, with no significant correlation with the rest of the parameters studied, although CSH was seen to be an indispensable prior requisite for adherence to cells.ConclusionCSH is a variable characteristic in C. albicans and is directly related to adherence to plastic and biofilm formation. Ease in evaluating CSH permits its quantification, and could be used as an indicator of the presence of other determinants of pathogenicity.     

Intra- and inter-cores fungal diversity suggests interconnection of different habitats in an Antarctic frozen lake (Boulder Clay,Northern Victoria Land)

A perennially frozen lake at Boulder Clay site (Victoria Land, Antarctica), characterized by the presence of frost mounds, have been selected as an in situ model for ecological studies. Different samples of permafrost, glacier ice and brines have been studied as a unique habitat system. An additional sample of brines (collected in another frozen lake close to the previous one) was also considered. Alpha- and beta-diversity of fungal communities showed both intra- and inter-cores significant (p < 0.05) differences, which suggest the presence of interconnection among the habitats. Therefore, the layers of frost mound and the deep glacier could be interconnected while the brines could probably be considered as an open habitat system not interconnected with each other. Moreover, the absence of similarity between the lake ice and the underlying permafrost suggested that the lake is perennially frozen based. The predominance of positive significant (p < 0.05) co-occurrences among some fungal taxa allowed to postulate the existence of an ecological equilibrium in the habitats systems. The positive significant (p < 0.05) correlation between salt concentration, total organic carbon and pH, and some fungal taxa suggests that a few abiotic parameters could drive fungal diversity inside these ecological niches.     

Ecological Diversification of Vibrio fischeri Serially Passaged for 500 Generations in Novel Squid Host Euprymna tasmanica

Vibrio fischeri isolated from Euprymna scolopes (Cephalopoda: Sepiolidae) was used to create 24 lines that were serially passaged through the non-native host Euprymna tasmanica for 500 generations. These derived lines were characterized for biofilm formation, swarming motility, carbon source utilization, and in vitro bioluminescence. Phenotypic assays were compared between “ES” (E. scolopes) and “ET” (E. tasmanica) V. fischeri wild isolates to determine if convergent evolution was apparent between E. tasmanica evolved lines and ET V. fischeri. Ecological diversification was observed in utilization of most carbon sources examined. Convergent evolution was evident in motility, biofilm formation, and select carbon sources displaying hyperpolymorphic usage in V. fischeri. Convergence in bioluminescence (a 2.5-fold increase in brightness) was collectively evident in the derived lines relative to the ancestor. However, dramatic changes in other properties—time points and cell densities of first light emission and maximal light output and emergence of a lag phase in growth curves of derived lines—suggest that increased light intensity per se was not the only important factor. Convergent evolution implies that gnotobiotic squid light organs subject colonizing V. fischeri to similar selection pressures. Adaptation to novel hosts appears to involve flexible microbial metabolism, establishment of biofilm and swarmer V. fischeri ecotypes, and complex changes in bioluminescence. Our data demonstrate that numerous alternate fitness optima or peaks are available to V. fischeri in host adaptive landscapes, where novel host squids serve as habitat islands. Thus, V. fischeri founder flushes occur during the initiation of light organ colonization that ultimately trigger founder effect diversification.