Phylogenetic analysis of AlaRS sequences. Neighbor-joining (NJ) tree
constructed by using the programs neighbor and
protdist (24), where the number of amino acid substitutions
per site in pairwise comparisons of aligned sequences (415 amino acids
in length) were estimated by using the Dayhoff 120 matrix (22). The
position of Giardia AlaRS is boxed. A similar tree
topology was determined in 100 replicate random heuristic searches by
using the maximum parsimony (MP) method (24) (one minimal length tree,
4821 steps long). ●, Those nodes supported in
70% or greater of 1,000 random bootstrap replicates of both MP and NJ
trees. Bootstrap values for critical nodes are shown as % of 1,000
replicates in MP/NJ methods. The node leading to G.
lamblia and archaeal species was consistently supported in
100% of replications. Furthermore, the shown tree topology was
significantly better statistically [Kishino-Hasegawa and Templeton
tests (25); P < 0.05] than all other alternative
topologies of the major groups, including one where eukaryotes and
G. lamblia were clustered together.