Acid hydrolases and their Release in Food Vacuole‐Less Mutants of Tetrahymena thermophila*

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Abstract
Mutants (NP1 and PSJ5) of T. thermophila strains B and D 1968 exist that are unable to construct a functional oral apparatus and form food vacuoles at 37.degree. C but which do so normally at 30.degree. C. Food vacuole-less cells starved in dilute salt solution released similar amounts of acid phosphatase, .beta.-N-acetylglucosaminidase and .alpha.-glucosidase activity into the medium as wild-type cells during an 8 h period. Actively growing, food vacuole-less cells had .apprx. 50% less total protein, acid phosphatase, .beta.-N-acetylglucosaminidase and .alpha.-glucosidase per cell than wild-type cells after 72 h growth. During this time food vacuole-less cells released significant amounts of the 3 acid hydrolases into the growth medium. For each hydrolase, the total activity released from growing, food vacuole-less cells was less, on a per cell basis, than the amount released from food vacuole formers. The proportion of the total activity secreted by the mutant and the wild-type cells was the same for acid phosphatase and .beta.-N-acetyl-glucosaminidase and somewhat lower for .alpha.-glucosidase. The release of a significant amount of acid hydrolase activity from Tetrahymena is apparently independent of food vacuole formation and may be analogous to the secretory activity of other nonphagocytic eukaryotic cells.