Trifluperidol (TFP), at a concentration of 100 ,M, inhibited the 24-h growth of Saccharomyces cerevisiae by about 30%. Effects on lipid metabolism were investigated by monitoring the incorporation of [1-14C]sodium acetate into various lipid fractions after 4 and 24 h of growth in the presence of several concentrations of TFP. Although little effect was noted on the amount of free sterols, 24-h incorporation of label into steryl esters was increased two-to fourfold by 100 ,M TFP. Major sterol components of the steryl ester fraction isolated from an untreated culture were zymosterol (48%) and ergosterol (24%), whereas from the TFP-treated culture A8 24(28)-ergostadienol (66.6%) and A8-ergostenol (14.7%) were most abundant. Free sterols present in the highest concentration in the untreated culture were ergosterol (78.2%) and lanosterol (13%); whereas A8'22_ ergostadienol (38.5%), A8-ergostenol (35.4%), and A8' 24(281-ergostadienol (25.4%) were the most abundant free sterols obtained from the TFP-treated culture. Thus, the major block in the sterol biosynthetic pathway in yeast appears to be A8-> A7 isomerization. In these same cultures the relative amounts of C12 and C14 acids isolated from both steryl ester and miscellaneous lipid fractions were increased more than threefold over controls.

Several methods for the extraction of lipids from intact yeast cells have been compared. Extraction of intact cells with methanol followed by methanol: benzene (1:1, v/v) and benzene resulted in the recovery of equal or greater amounts of polar and nonpolar lipids than obtained by other methods. A preparative method involving preincubation of cells with aqueous KOH followed by the treatment of the cellular residue as described above yielded slightly more steryl esters than was extracted from broken cell preparations.