Maud Bruneteau

Chromatographic purification and characterization of elicitors of necrosis on tobacco produced by incompatible Phytophthora species

Abstract A chromatographic procedure was developed to purify the proteins eliciting necrosis in tobacco and produced in culture by three species of Phytophthora: cryptogein from P. cryptogea, cinnamomin from P. cinnamomi and capsicin from P. capsici. The procedure included ion-exchange chromatography and gel filtration on Sephadex G-25. Polyacrylamide gel electrophoresis data and the amino acid composition are in agreement with a molecular mass near 10 000 for these proteins. Their behaviour on ion-exchange columns indicates that cryptogein and cinnamomin are basic proteins and capsicin an acidic one. In biological tests on excised tobacco leaf, cryptogein and cinnamomin exhibited an activity 50–100-fold that of capsicin.

Structure d'un dimycolate d'arabinose isole de Mycobacterium marianum

Resume Nous avons isole un glycolipide a partir des lipides lies de Mycobacterium marianum . Letude structurale par degradations chimiques et spectrometrie de masse montre la presence darabinose et de deux acides mycoliques, lun des acides mycoliques est un acide dicarboxylique monoethylenique qui possede la structure (III), lautre est un acide monocarboxylique, dicyclopropanique ayant la structure (IV) identique a celle de lacide α-kansamycolique. Ces deux acides esterifient les trois groupements hydroxyles de larabinose, ce qui conduit a la formule (V) pour le dimycolate darabinose.

Differential Elicitation Activities of Fractions from Phytophthora Spp. On Several Host-Plants

Early observations suggested that neutral polysaccharides from parasitic fungi could be universal elicitors of plant defence reactions [1]. However, more recent findings have indicated that unsaturated fatty acids and lipoconjugates are the active elicitors of phytoalexin accumulation in potato tubers [2]. But arachidonic and eicosapentaenoic acids are not universal elicitors either: they induce phytoalexin accumulation in potato and pepper, but not in twelve other plant species surveyed, including other Solanaceae, tobacco and tomato [3].

Composition des lipopolysaccharides de la souche sauvage P678 et de la souche mutante PM61 de Escherichia coli K12

The composition of the lipopolysaccharides from E. coli K12 P678 and from a mutant strain PM61 was investigated. No difference was found between the lipopolysaccharides of both strains. These bacteria belong to the CR34 serologic type in the group of E. coli K12.

Isolation and composition of glycolipids from corn flour

Total lipids extracted according to De Stefanis and Ponte [Biochim. Biophys. Acta, 176 (1969) 198–201] from corn flour (from Cameroon, variety white) amounted to 0·5% of the dry flour weight. The total lipids consisted of 90% neutral lipids, 5% glycolipids and 3% phospholipids. The glycolipids contained glucolipids as major components (4·5%) and minor amounts of a glycerolipidic fraction (0·6%). Glycolipid fatty acids were identified as linoleic, oleic and palmitic acids.