Jean Guillot

Lectins in higher fungi

Abstract The occurrence of lectins in higher fungi, localisation in the sporome and mycelium, levels according to different parameters and roles in the organism are reviewed. Chemical structure and specificity of lectins are examined. Applications of fungal lectins are discussed.

Volatile composition of Laetiporus sulphureus

Laetiporus sulphureus was investigated for volatile compounds by GC/MS. Twentysix components were identified with major constituents being (Z)-3-methylcinnamaldehyde (27.5%), 2-phenylethanol (6.4%), benzaldehyde (4.0%) and N-phenylethylformamide (3.8%). Odorous aromatic derivatives represented 11.5% of the volatile fraction. Observed sulphur derivatives contribute probably to the disagreeable odour of L. sulphureus developed in maturation process.

Purification of lectins from Ricinus communis by combination of affinity and ion-exchange chromatography and characterization of the isolated proteins

Lectins in the seeds of Ricinus communis L. were separated by affinity chromatography using stromata, and 3 fractions obtained by ion-exchange chromatography. Polyacrylamide-gel electrophoresis showed that 2 fractions were homogeneous and that 1 fraction gave 2 bands. Immunoelectrophoresis with rabbit antisera and polyacrylamide-gel isoelectric focusing showed that the 3 fractions were separate and distinct entities consisting of many proteins with isoelectric points near the isoelectric point of the main protein. The molecular weights of the separated proteins and their subunits were studied by SDS polyacrylamide-gel electrophoresis.

Purification and characterization of an anti-(A+B) specific lectin from the mushroom Hygrophorus hypothejus

A lectin (HHL) was isolated from the fruiting body of the mushroom Hygrophorus hypothejus by a combination of affinity chromatography on stromas of group B erythrocytes embedded in polyacrylamide gel, and DEAE-trisacryl and gel filtration chromatography. Its molecular mass, as determined by gel filtration, is estimated to be 68000 kDa and its structure is tetrameric with four identical subunits assembled with non-covalent bonds. HHL agglutinates specifically A and B blood group erythrocytes and in hemagglutination inhibition assays, exhibits sugar-binding specificity toward lactose, the anomeric alpha form being more effective than the beta form.

Intervention des lectines fongiques dans les événements précoces de reconnaissance arbre/champignon au cours de la formation des ectomycorhizes

Summary The occurence of lectin activity in a large number of higher fungi and the existence of an often high degree of specificity in the associations of fungi with trees prompted us to determine whether the fungal lectins might be involved in the recognition of the symbionts. To this end, we chose as a model the milk cap mushrooms of the Dapetes group, all of which are associated with conifers, but which exhibit a remarkable specificity. Thus, the morphologically very similar Lactarius deliciosus, Lactarius deterrimus, and Lactarius salmonicolor are associated with the pine, the spruce, and the fir, respectively. In order to back up the lectinic hypothesis, we have confirm three essential points: 1) The lectins isolated from the three milk cap mushrooms are different in structure and specificity. Although their molecular weight are very close, lectins have different subunits, isoelectric point and amino acid composition. All the lectins are specifically inhibited by the disaccharide D-Gals1 → 3D-GalNAc,...

Contribution to the morphological, cytological, and ultrastructural characterization ofPiromyces mae, a strictly anaerobic rumen fungus

Strictly anaerobic fungus species, present in the digestive tract of herbivores, are widely distributed, as confirmed by the discovery in France ofPiromyces mae Li in sheep rumen. By the study of a new strain, the morphological characteristics of this species were more accurately determined and the presence of megahydrogenosomes in its zoospores confirmed. Chitobiose,N-acetylgalactosamine, and arabinose were demonstrated on the thallic surface with lectins of different affinities for the sporangium or the rhizoids. In contrast toP. communis, there were no surface oligosaccharides with a terminal galactose bound toN-acetylgalactosamine orN-acetylglucosamine by a β 1→3 bond.

Use of yeasts in affinity chromatography.

The use of the yeast Candida lipolytica as a support in affinity chromatography for the purification of lectins of Ricinus communis seeds has been studied. A comparison was made with columns of erythrocyte stromas and Sepharose 4B with respect to protein yields, the agglutinating activity yield, and the electrophoretic characteristics of the eluted substances. Even though the yield is less than with other supports, it does appear that the yeast columns represent an effective method for the purification of ricin lectins.

P071 Rôle de l’adiponectine dans le contrôle de la cancérogenèse mammaire

Introduction et but de l’etude L’obesite apparait comme un facteur de risque de developpement d’un cancer du sein chez la femme en post-menopause. L’exces de tissu adipeux est associe a de nombreux desordres metaboliques et est notamment caracterise par la diminution du taux serique d’une adipokine : l’adiponectine. L’objectif de cette etude est de determiner si l’adiponectine est impliquee dans le developpement du cancer du sein. Aussi, nous avons evalue, d’une part, in vitro l’influence de l’adiponectine sur la proliferation cellulaire de la lignee cancereuse mammaire MCF7, et d’autre part, l’expression locale de l’adiponectine et de ses recepteurs (AdipoR1 et AdipoR2) sur des biopsies de tissu mammaire cancereux. Materiel et methodes Les cellules MCF7 (n=3) sont mises en contact avec 2 concentrations d’adiponectine : 1 μg/ml (concentration en situation d’obesite) et 10 (g/ml (concentration physiologique). Apres 24, 48, 72 et 96 h d’incubation, la proliferation cellulaire est mesuree par detection de fluorescence (resazurine). L’expression de l’adiponectine, d’AdipoR1 et AdipoR2 par le tissu mammaire cancereux (n=44) et le tissu sain environnant (n=39) est mise en evidence par immunohistochimie sur des biopsies (tumorotheque du Centre anti-cancereux Jean-Perrin). Resultats L’adiponectine (10 (g/ml) induit une diminution significative de la proliferation cellulaire de la lignee MCF7 de 10 %, 13 %, 18 % et 20 % a 24, 48, 72 et 96 h respectivement. L’adiponectine, a 1 (g/ml, induit une diminution significative de la proliferation de 5 % a 72 h L’activite antiproliferative de l’adiponectine a 10 (g/ml est significativement superieure a celle de la concentration de 1 (g/ml des 48 h Par ailleurs, au niveau des biopsies, le tissu cancereux exprime faiblement l’adiponectine (15 % des cas). Au contraire, le tissu sain myoepithelial environnant exprime fortement cette biomolecule (65 % des cas). De plus, AdipoR1 et AdipoR2 sont exprimes par le tissu cancereux (15 % et 80 % des cas respectivement) et par les cellules saines epitheliales adjacentes (5 % et 50 % des cas respectivement). Conclusions L’adiponectine exerce in vitro une activite anti-proliferative sur la lignee cellulaire MCF7. Cette biomolecule, via AdipoR1 et AdipoR2, serait susceptible de moduler la proliferation des cellules cancereuses et du tissu epithelial adjacent. Par ailleurs, les cellules saines myoepitheliales, contrairement au tissu cancereux, expriment fortement l’adiponectine. Ces resultats pourraient expliquer en partie les proprietes anti-tumorales des cellules myoepitheliales. Les liens entre adipokines et cancerogenese mammaire semblent donc etroits et ouvrent des perspectives d’investigation, notamment chez les patientes obeses pour lesquelles une diminution de l’adiponectine serique est decrite.