Project Information AT A GLANCE
Project Title: Regulation of pheromone receptor genes
Project Objective: The objective is to identify and understand, at a molecular level, the chemosensory tools and the corresponding neural circuitry that allow mammals to interact between each other.
Project Duration and Timing: 2010-2013
Project Funding: Swiss National Science Foundation
Project Partners: • Prof. P. Feinstein, Hunter College, New York.
generation of variety via DNA recombination; part of the genes that code for these receptors can be genetically mixed or reshuffled, so with just a few genes a lot of different products can be made. Other large receptor families have selected different strategies, such as alternative splicing. However, for chemoreceptors in the nose, this diversity is provided not by the association of bits of genes, but by the direct amplification of the gene repertoire. During evolution, these genes went through a copy/paste mechanism numerous times, which was followed by mutations that produced gigantic and diverse gene families. The mouse odorant receptor gene repertoire contains thus about 1500 genes, which represents a huge proportion of only 20,000 genes present in the entire mouse genome. “And we, humans, dispose of over 300 of them” says Rodriguez. “There is a remarkable diversity in
mammals’ abilities to face the outside world - and it is partly due to the different olfactory gene toolboxes they possess,” explains
Rodriguez. “Species diverge
rapidly in terms of the molecular tools they use; for example, rats and mice, or humans and chimps, although phylogenetically close, have remarkably different sets of receptors. This rapid birth - and death - of receptor genes in a given species is very unusual in biology and is one of the hallmarks of chemical sensing.” Rodriguez and his colleagues believe that these receptors may well have played a role
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in speciation events. Speciation most often occur as the result of physical isolation of colonies, but it is thought that it can also result from their chemical separation. “You could have animals of the same species in the same colony that inherit different chemical receptors, in particular those used to perceive pheromones. That generates individuals whose interest between each other is variable, sometimes absent, and lead
to a chemical isolation between
members of the same species.” Diversity in this chemosensory system
arises so quickly that it is very difficult to follow its
evolutionary history, looking
through mammals and vertebrates and trying to find orthologues (genes that emanate from the same ancestor). However, it makes the study of each given species very interesting in terms of what they have at their disposal, says Rodriguez. “Fish don’t have the same kind of chemosensory repertoires as other vertebrates that are living in contact with the air. Animals that live in groups have specific spheres of receptors, while animals that live alone have others. In every ecological niche and habitat, it is not only one or two receptors that have arisen but whole repertoires each containing dozens of different genes.” “It is fascinating for us as it links both
the evolution of species and their behaviour. We know what the different receptors are, but what we are trying to work out through our work is how the information is encoded and treated so that we can make sense of it.”
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Prof. Ivan Rodriguez Ivan Rodriguez obtained his PhD in Biology in 1997. He then spent 5 years as postdoctoral fellow at the Rockefeller University in New York, and is currently Professor in the Department of Genetics and Evolution at the University of Geneva, Switzerland, where he heads the Laboratory of Neurogenetics.
Contact: Tel: +41 22 379 31 01 Email:
Ivan.Rodriguez@
unige.ch Web:
http://genev.unige.ch/en/users/ Ivan-Rodriguez
• Prof. M. Spehr, Aachen University, Germany
• Prof. Alan Carleton, Geneva University, Switzerland
Main Contact:
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