Domains completeley homologous in the novel chitinases Chi2 and Chi3 as well as in the first A. astaci chitinase ( Chi1 , GenBank:AJ416354, ) were selected as primer target sites in the diagnostic assays for A. astaci. In blue: primer target sites. Note that only the homologous part of Chi1 is shown. The chitinase-like protein Clp mRNA (GenBank:FJ439176) was amplified from cDNA, but failed to amplify from genomic DNA for unknown reasons (data not shown). Chi1 peptide sequences selected to generate antibodies for Western blot analysis are underlined. Highly conserved motifs in the GH18 domain (grey boxes) were selected as primer target sites to identify the homologous genes of related oomycetes and relevant fungi (see text). Dots indicate missing sequence homology. The triangle marks the signal peptide cleavage site in Chi2 and Chi3. The catalytic-site residues D154, D156 and E158 putatively required for catalytic activity  are indicated by vertical arrows. Residues given as red or black letters represent mismatches and conservative changes, respectively. The conserved cysteines in the CB site 2 are highlighted in bold.