Jane-Marie Touzé-Soulet

Effects of triazoles on fungi. III. Composition of a plasma membrane-enriched fraction of Taphrina deformans *

Comparative chemical analyses were conducted with plasma membrane-enriched fractions of Taphrina deformans cells grown in a medium with or without the C-14 demethylation inhibitor propiconazole at a concentration that gives 50% growth inhibition. The membrane fractions were prepared using differential and discontinuous sucrose density gradient centrifugation, and characterized by cytochemical, enzymatic and chemical analyses. Membranes of nontreated cells were similar to those from other fungi with a protein/lipid ratio of 1.2, 13% phospholipid content in the membrane lipid (122 μg/mg protein), and a relatively high sterol/phospholipid molar ratio of 0.69. The corresponding membrane fraction from propiconazole-treated cells had 24% less lipid, 27% less phospholipid, 5-times more triacylglycerol relative to other neutral acyl lipids, and over a 2-fold higher sterol/phospholipid ratio. The greater sterol/phospholipid ratio was due to a higher C-14 methyl sterol content rather than less functional sterol (brassicasterol). Membranes from treated cells contained slightly less protein than those from nontreated cells, but there was little difference in the electrophoretic separation patterns of solubilized membrane polypeptides.

Effect of monensin on the lipid composition of Achlya bisexualis

Addition of various concentrations of monensin (1, 5 and 10 μg/ml) to the culture medium induced changes in the lipid composition of Achlya bisexualis . The total amount of lipids and sterols was reduced, whereas phospholipids were increased. In the phospholipid fraction, the proportion of arachidonic acid (C 20–4 ) was markedly increased in a dose-dependent manner.

Hyphal growth ofHypomyces chlorinus Tul.: An autoradiographic study

SummaryThe incorporation of the chitin precursor N-acetyl-D-(1-3H) glucosamine byH. chlorinus has been studied by light and electron microscopic autoradiography. Light microscopic autoradiography showed that the incorporation occured preferentially at the hyphal apex. Autoradiograms from electron microscopy were quantitatively evaluated to determine the relative radioactivity incorporation between the cell wall and cytoplasm: this showed that (3H) incorporation took place mainly in the plasmalemma-wall complex. However a small amount of N-acetyl glucosamine can enter into the cytoplasmic space and is then transported by endomembranes (Golgi apparatus-vesicles) to the plasmalemma-cell wall interface before polymerization.

Chitin synthesis in apical hyphal growth

CHITIN SYNTHESIS IN APICAL HYPHAL GROWTH. Robert DARGENT, 3ane-Marie TOUZE-SOULET and C. SAIDALI-SAVY. Laboratoire de Cryptogamie U.P.S., 118 route de Narbonne, 31062 TOULOUSE CEDEX. Vegetative hyphae grow by deposition of new material in the apical region. Electron microscopy of hyphal apices of Mucor mucedo and Hypomyces chlorinus shows the characteristic aggregation of vesicles which must have major roles in the apical biosynthesis of the hyphal wall, but the details of these role remains elusive. Furthermore the mechanism responsible for cell wall plasticity at the hyphal apex is not well understood. In the investigation of these problems we used three complementary methods ; cytochemical detection of polysaccharides ; specific labeling of chitin with n-acetyl [I-3H] glucosamine by light and electron microscopy ; distribution of chitin in cell walls using a WGA-colloidal gold complex as specific marker.

Mise en évidence d'une nouvelle forme combinée de l'acide glutamique dans le latex d'Euphorbia characias L

The hydro-alcoholic extract ofEuphorbia characias Latex contains one unknown amino acid and one new combined form of glutamic acid, isolated by preparative electrophoresis on cellulose powder.