title: MOXD2, a Gene Possibly Associated with Olfaction, Is Frequently Inactivated in Birds.
abstract: Vertebrate MOXD2 encodes a monooxygenase DBH-like 2 protein that could be involved in neurotransmitter metabolism, potentially during olfactory transduction. Loss of MOXD2 in apes and whales has been proposed to be associated with evolution of olfaction in these clades. We analyzed 57 bird genomes to identify MOXD2 sequences and found frequent loss of MOXD2 in 38 birds. Among the 57 birds, 19 species appeared to have an intact MOXD2 that encoded a full-length protein; 32 birds had a gene with open reading frame-disrupting point mutations and/or exon deletions; and the remaining 6 species did not show any MOXD2 sequence, suggesting a whole-gene deletion. Notably, among 10 passerine birds examined, 9 species shared a common genomic deletion that spanned several exons, implying the gene loss occurred in a common ancestor of these birds. However, 2 closely related penguin species, each of which had an inactive MOXD2, did not share any mutation, suggesting an independent loss after their divergence. Distribution of the 38 birds without an intact MOXD2 in the bird phylogenetic tree clearly indicates that MOXD2 loss is widespread and independent in bird lineages. We propose that widespread MOXD2 loss in some bird lineages may be implicated in the evolution of olfactory perception in these birds.
authors.affiliation: Department of Life Science, Research Center for Biomolecules and Biosystems, Chung-Ang University, Seoul, Republic of Korea.
authors.forename: Chul Jun
authors.initials: CJ
authors.lastname: Goh
authors.affiliation: Department of Life Science, Research Center for Biomolecules and Biosystems, Chung-Ang University, Seoul, Republic of Korea.
authors.forename: Dongjin
authors.initials: D
authors.lastname: Choi
authors.affiliation: Department of Life Science, Research Center for Biomolecules and Biosystems, Chung-Ang University, Seoul, Republic of Korea.
authors.forename: Dong-Bin
authors.initials: DB
authors.lastname: Park
authors.affiliation: Department of Life Science, Research Center for Biomolecules and Biosystems, Chung-Ang University, Seoul, Republic of Korea.
authors.forename: Hyein
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Life Science, Research Center for Biomolecules and Biosystems, Chung-Ang University, Seoul, Republic of Korea.
authors.forename: Yoonsoo
authors.initials: Y
authors.lastname: Hahn
mesh_terms: D000818:Animals; D001717:Birds / Q000235:genetics*; D005091:Exons; D020868:Gene Silencing; D016678:Genome; D008565:Membrane Proteins / Q000235:genetics*; D006899:Mixed Function Oxygenases / Q000235:genetics*; D009154:Mutation; D010802:Phylogeny; D017384:Sequence Deletion; D012903:Smell / Q000235:genetics*
chemical_list: D008565:Membrane Proteins; D006899:Mixed Function Oxygenases