Analysis of Mitochondrial DNA Variation as an Approach to Systematic Relationships in the Genus Acanthamoeba¹

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.

Mitochondrial DNA Restriction Fragment Length Polymorphism (RFLP) and 18S Small-Subunit Ribosomal DNA PCR-RFLP Analyses ofAcanthamoebaIsolated from Contact Lens Storage Cases of Residents in Southwestern Korea

“…Costas and Griffiths (13) considered that the vari-ation among some Acanthamoeba species overlaps so extensively that the amoebae should be regarded as species complexes. Mitochondrial DNA (mtDNA) restriction fragment length polymorphism (RFLP) analysis has also been applied for taxonomy analysis of Acanthamoeba (2,3,58,59). However, considering the profound interstrain diversity of the mtDNA RFLP and alloenzyme profiles, Kong et al (28) and Chung et al (6) suggested that both analyses should be used for the strain identification, differentiation, and characterization rather than species identification.…”

Isolates from ancient permafrost help to elucidate species boundaries in Acanthamoeba castellanii complex (Amoebozoa: Discosea)

“…This holds for T4 type as well. Also, even an early mitochondrial RFLP study (Byers, Bogler, & Burianek, 1983) has revealed remarkable heterogeneity inside 16S-T4 comparable to that found in 18S-T4. At the same time, this study has discovered the major inconsistency between 18S and 16S phylogenies: Castellani and Ma strains (18S-T4 A and T4 B , correspondingly) appeared closely related and showed differences at the level of intraspecific variation in other organisms.…”

Isolation, Identification and Increasing Importance of 'Free-Living' Amoebae Causing Human Disease

“…DNA fragment size polymorphisms were used to estimate nucleotide sequence polymorphisms, in the expectation that the latter would correlate with the overall genetic relatedness of the various strains [81]. Ten distinct families of electrophoretic patterns (digestion genotypes) were observed [77].…”

“…Consequently, little is known about the genetic relationships between pathogenic and nonpathogenic strains of Acanthamoeba. Several studies report on the analysis of mitochondria1 DNA (mtDNA) variation in members of the genus Acanthamoeba as an aid in taxonomy [21,[24][25][26]711. This method has proved to be a useful approach to studying evolutionary relationships among closely related organisms [ 72, 731.…”

“…Morphological criteria are inadequate for the distinction of pathogenic and non-pathogenic strains [5,6,20,231. Differences in antigenic determinants have been found between pathogenic and non-pathogenic Naegleria strains [7,201, while determination of the iso-enzyme profile by iso-electric focusing and analysis of mitochondria1 or whole-cell DNA profiles also seem to be promising [5,6,21,22,[24][25][26].…”