Evidence for a second chemotactic system in the cellular slime mold, Polysphondylium.

An unidentified substance(s) in a commercial guanosine 3′,5′-cyclic monophosphoric acid (cyclic 3′,5′-GMP) preparation is effective in attracting the aggregating amoebae of the cellular slime mold, Polysphondylium pallidum. Bacterial extracts (Escherichia coli) and amoeba extracts (P. pallidum) attract both vegetative and aggregating amoebae. A crude enzyme preparation from amoebae is capable of reducing the chemotactic activity of the extracts on aggregating amoebae and eliminating the activity of the unknown substance in the commercial cyclic 3′,5′-GMP preparation. As only the extracts were shown to contain folic acid, and since the enzyme does not reduce folic acid activity, it is suggested that the extracts contain a factor (possibly folic acid) primarily active on vegetative amoebae and an acrasin. The commercial cyclic 3′,5′-GMP preparation contains only an acrasin. The acrasin is heat stable and nondialyzable.