Nucleotide variation in the cytidine triphosphate synthetase gene of Giardia duodenalis

The cytidine triphosphate synthetase genes from three diverse strains of Giardia duodenalis have been sequenced and found to vary significantly from one another. The isolates were chosen as representatives of three demes as determined by several criteria including divergence in the rDNA repeat unit. Inserts in the genes and protein are conserved in length but are the most divergent regions among the three sequences examined. Variation in the rest of the gene occurs primarily in the third base position resulting in many silent mutations. One of the isolates (1709) was found to contain two genes with high sequence homology.