Table 2 summarises these ALDH orthologues, their chromosomal locations and the associated NCBI Entrez gene identification (ID) number for each of the 11 species. For zebrafish, Entrez gene ID 100334142 was listed as 'aldehyde dehydrogenase 1A1-like [D. rerio]'. This gene record appears to be derived from an unplaced chromosomal fragment, however, because no genome location could be determined. In addition, alignment of the peptide sequence for this gene ID to other mammalian ALDH1A1 protein sequences was poor. Specifically, sequence homology with human, mouse and rat ALDH1A1 was only 26.2 per cent, 26.4 per cent and 26.8 per cent, respectively. NCBI BlastP analysis indicated that it most closely resembles bacterial ALDH proteins. Together, this evidence suggests that this record may represent bacterial contamination, rather than a true zebrafish gene; thus, we have not included this gene. This also makes the zebrafish the only species among the 11 analysed that lacks a record for ALDH1A1. Interestingly, a protein blast (blastp) search using human ALDH1A1 and limiting results to fish species only (NCBI taxid: 7898) revealed ALDH1A2 homologues in multiple species (including salmon,
