PUBLICATION
Positive Darwinian selection and the birth of an olfactory receptor clade in teleosts
- Authors
- Hussain, A., Saraiva, L.R., and Korsching, S.I.
- ID
- ZDB-PUB-090302-20
- Date
- 2009
- Source
- Proceedings of the National Academy of Sciences of the United States of America 106(11): 4313-4318 (Journal)
- Registered Authors
- Korsching, Sigrun, Saraiva, Luis
- Keywords
- Danio rerio, evolution, in situ hybridization, shark, trace amine
- MeSH Terms
-
- Animals
- Evolution, Molecular*
- Fishes
- Olfactory Receptor Neurons
- Phylogeny
- Receptors, G-Protein-Coupled/genetics
- Receptors, Odorant/genetics*
- Selection, Genetic*
- PubMed
- 19237578 Full text @ Proc. Natl. Acad. Sci. USA
Citation
Hussain, A., Saraiva, L.R., and Korsching, S.I. (2009) Positive Darwinian selection and the birth of an olfactory receptor clade in teleosts. Proceedings of the National Academy of Sciences of the United States of America. 106(11):4313-4318.
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 d(N)/d(S) 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.
Genes / Markers
Expression
Phenotype
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Fish
Orthology
Engineered Foreign Genes
Mapping