Odd-and even-numbered fatty acids. Their contrasting behavior in normal and fowlpox virus-infected epithelium

Upon infection with fowlpox virus, the amount of odd-numbered fatty acids in chick scalp epithelium shows a significant decrease compared with control values. This effect begins quite early and progresses throughout the period of infection. Individual members of the odd-numbered family (C15--C27 inclusive) were quantitatively related to the group as a whole during most of the infection. Experiments involving the administration of labeled acetate in vivo demonstrated an increase in the synthesis of even-numbered fatty acids and a decrease in the synthesis of odd-numbered fatty acids in infected epithelium. The reduced synthesis of odd-numbered fatty acids in infected epithelium could also be demonstrated with labeled propionate. The influence of the alpha-oxidation pathway was assayed in chick scalp epithelium in vivo by the administration of [1-14C,9,10-3H] stearic acid. The C17 acids formed had a 3H/14C ratio similar to that of the C16 acids, indicating that most label incorporation into C17 was due to beta-oxidation to acetate followed by resynthesis into fatty acids. C17 fatty acids from control and infected epithelium had similar 3H/14C ratios, indicating that the alpha-oxidation pathway probably does not contribute to the differences in odd-numbered fatty acid content observed. In assays for fatty acid synthetase activty, both [14C] acetyl-CoA and [14C]-propionyl-CoA were used as initial acceptors. The specific activities of preparations from infected scalp were similar to those of control preparations with both substrates. These results suggest that there is no decline in the ability to utilize propionate for fatty acid synthesis in infected epithelium.