Journal of Comparative Physiology A

, Volume 183, Issue 5, pp 635–650

Olfactory receptors in aquatic and terrestrial vertebrates

  • J. Freitag
  • G. Ludwig
  • I. Andreini
  • P. Rössler
  • H. Breer
ORIGINAL PAPER

DOI: 10.1007/s003590050287

Cite this article as:
Freitag, J., Ludwig, G., Andreini, I. et al. J Comp Physiol A (1998) 183: 635. doi:10.1007/s003590050287

Abstract

In species representing different levels of vertebrate evolution, olfactory receptor genes have been identified by molecular cloning techniques. Comparing the deduced amino-acid sequences revealed that the olfactory receptor gene family of Rana esculenta resembles that of Xenopus laevis, indicating that amphibians in general may comprise two classes of olfactory receptors. Whereas teleost fish, including the goldfish Carassius auratus, possess only class I receptors, the `living fossil' Latimeria chalumnae is endowed with both receptor classes; interestingly, most of the class II genes turned out to be pseudogenes. Exploring receptor genes in aquatic mammals led to the discovery of a large array of only class II receptor genes in the dolphin Stenella Coeruleoalba; however, all of these genes were found to be non-functional pseudogenes. These results support the notion that class I receptors may be specialized for detecting water-soluble odorants and class II receptors for recognizing volatile odorants. Comparing the structural features of both receptor classes from various species revealed that they differ mainly in their extracellular loop 3, which may contribute to ligand specificity. Comparing the number and diversity of olfactory receptor genes in different species provides insight into the origin and the evolution of this unique gene family.

Key words Olfactory receptorsMultigene familiesPseudogenesVertebrate speciesEvolution

Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • J. Freitag
    • 1
  • G. Ludwig
    • 1
  • I. Andreini
    • 1
  • P. Rössler
    • 1
  • H. Breer
    • 1
  1. 1.University Stuttgart-Hohenheim, Institute of Physiology, Garbenstrasse 30, D-70593 Stuttgart, Germany e-mail: physioll@uni-hohenheim.de Tel.: +49-711-459-2266; Fax: +49-711-459-3726DE