ESTIMATION OF GENETIC-VARIATION AMONG SOIL ISOLATES OF COLPODA-INFLATA (STOKES) (PROTOZOA, CILIOPHORA) USING THE POLYMERASE CHAIN-REACTION AND RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM ANALYSIS

The genetic diversity among fifteen geographical isolates of Colpoda inflata was estimated using a simple, rapid method employing the polymerase chain reaction (PCR) in conjunction with restriction fragment length polymorphism (RFLP) analysis. We used the PCR to amplify an approximately 760 bp region within the large subunit ribosomal RNA (rRNA) gene and conducted RFLP analysis using nine restriction enzymes that were known to cut the region of DNA amplified. The patterns generated from the restriction enzymes were compared among the clonal isolates cultured from soils collected from three different continents to estimate their level of genetic relatedness. A total of eight different composite haplotypes were found, two that were widely distributed and six haplotypes that were unique to a single location. Populations in which multiple clones were examined exhibited no genetic variation. Divergence among the different composite haplotypes was low (0.0038 to 0.033 base substitutions per nucleotide), and phenetic analysis of the haplotypes did not reveal any discernible biogeographic pattern. Results suggest that the cosmopolitanly distributed C. inflata has undergone limited genetic differentiation, and that the dispersal of this cyst-forming ciliate is probably a result of stochastic events.