title: Analysis of planarian Adh3 supports an intron-rich architecture and tissue-specific expression for the urbilaterian ancestral form.
abstract: The alcohol dehydrogenase class 3 enzyme (ADH3) is the presumed ancestral form of the medium-chain dehydrogenase-reductase ADH family. This enzyme has been involved in formaldehyde and nitric oxide metabolism of a variety of deuterostomes and ecdysozoan protostomes. We have now characterized the structure and expression of the Adh3 gene in the lophotrochozoan Schmidtea mediterranea, a freshwater planarian. The planarian gene expands over 8.7 kb and is organized into 7 exons. The 1340 bp long Adh3cDNA contains a 1137 bp open reading frame corresponding to a deduced protein of 379 amino acids. The protein sequence is consistent with that expected for a typical class III enzyme. Twenty out of the twenty-two amino acid positions associated with enzymatic roles are strictly preserved, which suggests that the enzymatic capabilities have been conserved. In situ hybridization experiments show that Adh3 is expressed along the intestine of S. mediterranea specimens. This is consistent with the pattern observed in invertebrates and in contrast with the widespread expression of vertebrate Adh3. The comparative study across bilateria, which now includes a lophotrochozoan representative, further supports the idea that the urbilaterian Adh3 ancestor showed an intron-rich architecture and tissue-specific expression, and strengthens the view that widespread expression of Adh3 was a vertebrate innovation.
authors.affiliation: Departament de Genètica, Facultat de Biologia, Universitat de Barcelona. Av. Diagonal, 645, E-08028 Barcelona, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Godoy
authors.forename: Roser
authors.initials: R
authors.lastname: Gonzàlez-Duarte
authors.forename: Ricard
authors.initials: R
authors.lastname: Albalat
mesh_terms: D000426:Alcohol Dehydrogenase / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018076:DNA, Complementary / Q000235:genetics; D041981:Gastrointestinal Tract / Q000502:physiology; D015870:Gene Expression; D007438:Introns; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010614:Pharynx / Q000502:physiology; D010802:Phylogeny; D010932:Planarians / Q000235:genetics* / Q000502:physiology; D012038:Regeneration; D017386:Sequence Homology, Amino Acid; D012926:Social Control, Formal
chemical_list: D018076:DNA, Complementary; D000426:Alcohol Dehydrogenase