Positive Darwinian selection and the birth of an olfactory receptor clade in teleosts

Ashiq Hussain, Luis Miguel Rodrigues Saraiva, Sigrun I. Korsching

Research output: Contribution to journalArticle

92 Citations (Scopus)

Abstract

Trace amine-associated receptors (TAARs) in mammals recently have been shown to function as olfactory receptors. We have delineated the taar gene family in jawless, cartilaginous, and bony fish (zero, 2, and >100 genes, respectively). We conclude that taar genes are evolutionary much younger than the related OR and ORA/V1R olfactory receptor families, which are present already in lamprey, a jawless vertebrate. The 2 cartilaginous fish genes appear to be ancestral for 2 taar classes, each with mammalian and bony fish (teleost) representatives. Unexpectedly, a whole new clade, class III, of taar genes originated even later, within the teleost lineage. Taar genes from all 3 classes are expressed in subsets of zebrafish olfactory receptor neurons, supporting their function as olfactory receptors. The highly conserved TAAR1 (shark, mammalian, and teleost orthologs) is not expressed in the olfactory epithelium and may constitute the sole remnant of a primordial, nonolfactory function of this family. Class III comprises three-fourths of all teleost taar genes and is characterized by the complete loss of the aminergic ligand-binding motif, stringently conserved in the other 2 classes. Two independent intron gains in class III taar genes represent extraordinary evolutionary dynamics, considering the virtual absence of intron gains during vertebrate evolution. The dN/dS analysis suggests both minimal global negative selection and an unparalleled degree of local positive selection as another hallmark of class III genes. The accelerated evolution of class III teleost taar genes conceivably might mark the birth of another olfactory receptor gene family.

Original languageEnglish
Pages (from-to)4313-4318
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume106
Issue number11
DOIs
Publication statusPublished - 17 Mar 2009
Externally publishedYes

Fingerprint

Odorant Receptors
Parturition
Genes
Fishes
Introns
Vertebrates
Olfactory Receptor Neurons
Lampreys
Sharks
Olfactory Mucosa
Zebrafish
Amines
Mammals

Keywords

  • Danio rerio
  • Evolution
  • In situ hybridization
  • Shark
  • Trace amine

ASJC Scopus subject areas

  • General

Cite this

Positive Darwinian selection and the birth of an olfactory receptor clade in teleosts. / Hussain, Ashiq; Rodrigues Saraiva, Luis Miguel; Korsching, Sigrun I.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 106, No. 11, 17.03.2009, p. 4313-4318.

Research output: Contribution to journalArticle

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