The lipid composition of five parasitic and six saprophytic leptospires was compared. Lipids comprise 18 to 26% of the dry weight of the cells after chloroformmethanol extraction. No residual (bound) lipid was found after acid or alkaline hydrolysis of the extracted residue. The total lipid was composed of 60 to 70'phospholipid, and the remaining lipid was free fatty acids. The phospholipid fraction contained phosphatidylethanolamine as the major component, and phosphatidylglycerol and diphosphatidylglycerol were minor components with traces of lysophatidylethanolamine sometimes found. The major fatty acids of leptospires were hexadecanoic, hexadecenoic, and octadecenoic acids. Both the unusual cis-11hexadecenoic acid and the more common cis-9-hexadecenoic acid were synthesized by the leptospires. Neither the parasitic nor the saprophytic leptospires can chain elongate fatty acids. However, they were capable of 3-oxidation of fatty acids. Both groups of leptospires desaturate fatty acids by an aerobic pathway. When the parasite canicola was cultivated on octadecanoic acid, 87% of the hexadecenoic acid was the 11 isomer, whereas the saprophyte semeranga consisted of 10%,o of this isomer. In addition, the saprophytic leptospires contained more tetradecanoic acid than the parasites. No differences were observed in the lipid composition of virulent and avirulent strains of canicola.on August 6, 2020 by guest http://iai.asm.org/ Downloaded from

The paper contains data on the induction of K+ efflux and viability of baby hamster kidney (BHK-21) cells after their treatment with macrolide antibiotics inducing specific pores in membrane. New water-soluble semisynthetic derivatives of amphotericin B and aureofacin (N-glycosyl and trimethylammonium methyl ester derivatives) as well as the parent compounds were used to compare the concentration of antibiotics inducing permeabilizing and cytostatic effects. We found that a two-to eight-times-higher concentration of polyene antibiotic was required to observe a cytostatic effect than for release of 50% of the cellular potassium (Kr5o concentration) from BHK-21 cells. These differences were larger for water-soluble derivatives than for the parent compounds. The amount of intracellular potassium in treated cells incubated under optimal growth conditions was higher than that in cells which had been further washed with K+-free maintenance medium. The membrane permeability changes induced by low concentrations of specific polyenes were observed to be reversible. BHK-21 cells were able to repair polyene-induced membrane permeability within 3 to 12 h under optimal growth conditions, after cell treatment with K5w concentration of specific macrolide antibiotics. The repair phenomenon is postulated as an explanation for the dissociation observed between permeabilizing and cytostatic effect of specific polyenes in BHK-21 cells.

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It is recognized that microorganisms of the psittacosis group are contained within a rigid envelope (Hamre, Rake, and Rake, 1947) which is highly resistant to enzymes (Brown, Itatani, and Moulder, 1952) and mechanical disintegration (Ross and Gogolak, 1957). With the demonstration that penicillin inhibits the growth of bacteria by interfering with cell wall synthesis (Park and Strominger, 1957; Hahn and Ciak, 1957; Lederberg, 1957), the susceptibility of members of the psittacosis group to penicillin (Hurst, 1953) suggested that their outer envelopes might be analogous to the cell walls of bacteria. Since these structures have properties not encountered in other kinds of cells (Cummins and Harris, 1956; Salton, 1956; Work, 1957; Mitchell, 1959), the association of a reasonable number of these unique properties with the outer envelopes of members of the psittacosis group would be of decisive weight in establishing their evolutionary origin. This report describes the isolation and chemical characterization of the rigid envelopes of the agent of meningopneumonitis, a typical member of the psittacosis group. These structures will from now on be called cell walls as a matter of convenience and without any immediate implication of analogy or lack of analogy with bacterial cell walls. Their serological properties will be reported elsewhere (Jenkin, Ross, and Moulder, unpublished data)