Lipid inclusions in the vacuoles of Saccharomyces cerevisiae

Summary Spherical or elongated phospholipid inclusions have been observed in vacuoles of Saccharomyces cerevisiae. The periodicity of these lipid inclusions is 56 Å and the material of which they are composed appears to be derived from spherosomes. The spherosomes arise in the cytoplasm, penetrate the tonoplast, and discharge their contents into the vacuole. It is postulated that the phospholipid matrix of the spherosome then aggregates to produce the myelin-like inclusions. Tween 80 and ergosterol together in the growth medium do not prevent the formation of the lipid inclusions.