No abstract

Classification at the species level has been difficult in the genus Acanthamoeba. The taxonomic designations of a number of strains are in doubt and new approaches to classification are needed. We describe the use of electrophoretic patterns obtained with restriction enzyme digests of mitochondrial DNA as a basis for one new approach. Results from analysis of ten strains of A. castellanii, two of A. polyphaga and one of A. astronyxis are discussed. Examples both of nucleotide sequence diversity and of sequence conservation have been found among strains with the same species designation. Five strains from Europe, North America and New Zealand had identical digestion phenotypes with five enzymes; consequently, very similar nucleotide sequences are predicted. All are pathogenic to humans or mice. The mtDNA sequences of eight remaining strains are predicted to differ from this cluster and, in most cases, from each other at least as much as in sibling species of Paramecium aurelia.