Analysis of aspartic peptidases, Cathepsin D. (A) Phylogenetic tree based on maximum likelihood analysis of a Dermacentor variabilis midgut protein and published sequences. The transcripts identified in this analysis are in bold (DvM). Phylogenetic analysis was conducted on protein alignments using Tree Puzzle version 5.2. Values at nodes represent calculated internal branch node support (1000 replications). (B) Multiple sequence alignment (CLUSTALX) of protein sequences identified in a cDNA library of unfed/2 d fed or 6 d fed D. variabilis midguts (DvM) and published sequences found on Genbank. Arrowheads indicate conserved aspartic catalytic sites and diamonds indicate putative glycosylation residues (nomenclature derived from Boldaatar et al. (49). Shading represents 100% identity (black) or similarity (grey) among the sequences. Alignments were conducted using CLUSTALX. D. variabilis (Dv), Drosophila melanogaster (Dm), Bombyx mori (Bmori), Haemaphysalis longicornis (Hl), Ixodes ricnius (Ir), and Rhipicephalus (Boophilus) microplus (Bm), Ancylostoma caninum (Ac), Sus scrofa (Ss), Rattus norvegicus (Rn).