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I . Escherichia coli and mixed cultures of rumen bacteria were grown with [8J4C]adenine to label their nucleic acids specifically.2. The labelled bacteria were injected into the rumen of sheep and the radioactivity incorporated into tissue nucleic acids and that excreted in the urine and faeces was determined.3. The radioactivity was present in the cold trichloroacetic acid-soluble fraction and the RNA and DNA fractions of all tissues examined. Liver, kidney, spleen, and blood had the highest levels of radioactivity. 4. The radioactivity of the RNA was present only in adenosine monophosphate and guanosine monophosphate.

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The effect of subinhibitory concentrations of octenidine and pirtenidine on the lipid and sterol composition of Candida albicans was investigated. The total lipid and sterol contents of C. albicans grown in the presence of either octenidine or pirtenidine were reduced compared with control-grown cells. The major differences in the lipid composition of drug-grown and control cells were phosphatidylglycerol, phosphatidylcholine and monogalactosyldiacylglycerol, which increased in the presence of octenidine and pirtenidine. Lower proportions of phosphatidic acid were found in yeasts grown in the presence of the drugs when compared with control C. albicans. Fatty acid analysis of control-grown cells showed that the major fatty acids were C₁₆ and C₁₈. Drug-grown cells had higher proportions of palmitic and linolenic acids but lower proportion of oleic acid. The C₁₆/C₁₈ ratios were higher for octenidine- and pirtenidine-grown cells than control cells. Differences in the fatty acid composition of major phospholipids and neutral lipids between drug-grown and control yeasts were also observed. Sterol analysis of control-grown cells showed that the major sterol present was ergosterol (65.9%). A significant increase in squalene and 4,14-dimethylzymosterol was observed in pirtenidine-treated cells, while octenidine-treated cells showed an increase in zymosterol and obtusifoliol contents. Our results suggest that octenidine and pirtenidine affect the lipids and sterol of C. albicans in different ways. The implications of these findings on the mode of action of these two drugs is discussed.

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