Biomedical subjects

R Bonaly

Publications and source records attributed to R Bonaly.

60 records · Page 4Linked to original sources

PubMedDate not supplied

Study on agglutinating factors from flocculent Saccharomyces cerevisiae strains.

The lectin-like theory suggest that yeast flocculation is mediated by an aggregating lectinic factor. In this study we isolated an agglutinating factor, which corresponds to lectin, from whole cells by treating the flocculent wild-type Saccharomyces cerevisiae NCYC 625 strain and its weakly flocculent mutant [rho degrees ] with EDTA and two non-ionic surfactants (Hecameg and HTAC). The dialysed crude extracts obtained in this way agglutinated erythrocytes and this hemagglutination was specifically inhibited by mannose and mannose derivatives. However, SDS-PAGE profiles showed that the three reagents had different effects on the yeast cells. The non-ionic surfactants appeared to be the most efficient, as their extracts possessed the highest specific agglutinating activity. The products released by the wild-type strain presented a higher specific agglutinating activity than those released by the [rho degrees ] mutant. Purification of the agglutinating factor from extracts of both strains by affinity chromatography revealed two active bands of relative mass of 26 and 47 kDa on SDS-PAGE. Mass spectrometry analysis by MALDI-TOF, identified a 26 kDa band as the triose phosphate isomerase (TPI) whereas a 47 kDa band was identical to enolase. Edman degradation showed that the N-terminal sequences of these proteins were similar to TPI and enolase, respectively. The difference in the flocculation behaviour of the two strains is due to changes in the protein composition of the cell wall and in the protein structure involved in cell-cell recognition.

Agglutinins↗

PubMedDate not supplied

[Changes in the cell wall of Candida albicans cultivated in the presence of sublethal doses of nystatin].

Subinhibitory doses of nystatin in the culture medium of Candida albicans gave yeasts with altered cell walls. Major alterations chiefly concerned the antigenic peptidomannans. Their amount in wall and their molecular weight were smaller in yeast grown with nystatin than in normal cultured yeast. Glucans and chitin were not seriously modified. Polymers requiring lipidic intermediates such as dolichol phosphate for their biosynthesis seemed to be most affected by the presence of nystatin.

Amino Acids↗

PubMedDate not supplied

Cell targeting by glycosidic telomers. Specific recognition of the Kb CWL1 lectin by galactosylated telomers.

This work deals with the synthesis and lectinic recognition ability of galactosylated telomers. To investigate if telomeric carriers could exhibit cellular recognition properties, we have synthesized mono- and polygalactosylated tris(hydroxymethyl)acrylamidomethane (THAM) telomers. The affinity of such macromolecular drug carriers toward a receptor, the yeast Kb CWL1 lectin, was defined, and the influence of mono- or polygalactosylation of THAM units on the recognition phenomenon was assessed. The lectinic affinity of the compounds was estimated by measuring the inhibition of yeast aggregation. The average degree of polymerization as well as the hydrophilic-lipophilic balance of such galactosylated telomers affects their recognition ability for the lectin.

Chemical Phenomena↗

PubMedDate not supplied

Permeability of yeast cell envelope to fluorescent galactosylated telomers derived from THAM.

The work reported herein deals with the study of cellular recognition and permeability phenomena in yeasts. Various galactosylated organic telomers derived from trishydroxymethyl-aminomethane (THAM) and bearing fluorescent moieties were synthesized in order to measure their ability to cross the yeast cell envelope. Grafting fluorescent probes on the organic telomer backbone allowed us to study their specific behaviors toward the yeasts by fluorescence microscopy. Yeasts belonging to the genera Kluyveromyces and Saccharomyces were used for this study. With Saccharomyces yeast cells bearing mannose-specific lectins or lectin-like proteins, on their outer surface, all the galactosylated or nongalactosylated organic telomers passed through the cell envelope and invaded the cytoplasm. With Kluyveromyces yeast cells bearing galactose-specific lectins, the galactosylated organic telomers were blocked at the outer surface while the nongalactosylated derivatives crossed the cell envelope. Moreover, preincubation of Kluyveromyces yeasts with galactose or methylgalactose inhibited the cell surface anchorage of the organic telomers and allowed their penetration into the cytoplasm. When assays were performed on spheroplasts of both Kluyveromyces and Saccharomyces yeasts, no fixation on the surface could be observed, and all the derivatives went through the membrane and invaded the cytoplasm.

Acrylates↗

PubMedDate not supplied

[Study of PLi genes action on the cell wall structure of "Saccharomyces cerevisiae" Hansen (author's transl)].

A study of the composition of cell walls extracted from a wild strain and three mutant strains "smooth colony" of Saccharomyces cerevisiae had been done. It points out differences in the mannose/glucose ratio and in the concentration of some other components of the cell wall in the mutant strains. The immunological study of the cell wall shows that "smooth colonies" mutants and wild strains differs in their mannoproteins.

Cell Wall↗

PubMedDate not supplied

[Specific soluble cell-wall antigens of "Candida tropicalis" demonstrated by crossed immunoelectrophoresis (author's transl)].

In the present study, soluble cytoplasmic extracts of Candida albicans and C. tropicalis were prepared and showed respectively 67 and 47 precipitates in crossed immunoelectrophoresis performed with a commerical goat anti-C. albicans immunserum. Purified cell walls of C. tropicalis have been prepared, and corresponding antiserum was got in rabbits. Although important cross-reacting antigens exist between soluble cytoplasmic extracts of C. albicans and C. tropicalis, the C. tropicalis cell wall antiserum precipitated antigens in crossed immunoelectrophoresis only in C. tropicalis soluble cytoplasmic extracts. The present study: - confirms that C. albicans shared 70% of the antigens with C. tropicalis; - demonstrates that soluble cytoplasmic antigens prepared by homogenization of yeasts contain cell wall constituents; - allows us to prepare a specific immune serum for C. tropicalis.

Animals↗