Resumption of locomotion byAmoeba proteus readhering to different substrata

Summary Floating heterotactic cells ofAmoeba proteus were sedimented on untreated glass surfaces and on modified substrata, differing in their wettability and surface potential. About 95% of the amoebae readhere to the glass within 12 min and recover locomotive (polytactic) morphology within 13 min. The rate of locomotion resumption does not change significantly on styrene/methyl methacrylate co-polymers with contrasting hydrophilic sulfonic group surface densities. Almost all amoebae readhere within 3 min to the positively charged surface of polylysine-coated glass, but locomotive shape is only reassumed after 20 min by 95% of them. The polytactic cells are marked flattened on polylysine and move 2 1/2 times more slowly than on the glass. Floating amoebae never readhere to negatively charged gelatin gel; up to 25% become polytactic after 20 min, but they never resume locomotion. Indifference of amoebae to substratum wettability, and their prompt reaction to the positively or negatively charged surfaces, are discussed. The polylysine and gelatin gel substrata seem suitable for the study of adhesion dependent motor functions in amoebae.