Hi all, Dont miss todays Biology Seminar on how host specificity of blood sucking mosquitoes might be encoded by the olfactory system. The talk will be given by Dr. Sharon Rose Hill from the Chemical Ecology group at SLU, Alnarp. It will be good for sure! Same place and time as last week, i.e. RED ROOM at 13:00 Title: Molecular basis for odourant receptor tuning: a short C-terminal sequence is necessary and sufficient for selectivity. Abstract: A birth-and-death model of evolution for odourant receptor gene repertoires presumes the creation of repertoires with the capacity for both a high level of diversity and a rapid changing of ligand specificity. This, in turn, changes the odour space recognised by the repertoire, which can directly affect fitness-related behaviours and ultimately affect the adaptation to new environments and resources. The proximate molecular mechanism(s) underlying the tuning of these odourant receptor repertoires, and thus the peripheral olfactory system, are unclear. Here, we present a concrete example of the birth-and-death model of odourant receptor evolution leading to rapid changes in receptor tuning that leave the peripheral neuronal circuitry intact. We identified a conserved odourant receptor gene in mosquitoes, Or8, which in one species, Culex quinquefasciatus, underwent a duplication and inversion event. The resulting paralogue is highly similar with only minor localised differences in structure manifesting in the c-terminus of the receptor. We assessed the specificity of the paralogous odourant receptors and receptor neurones, to their cognate ligand, (R)-1-octen-3-ol, and its enantiomer, (S)-1-octen-3-ol. We found that the functional tuning of the receptor was indeed reflected in minor differences in amino acid structure. Specifically, we found that enantiomeric specificity of these mosquito Or8 paralogues relies on a subset of eight c-terminal amino acids encoded in the final exon of the gene. Thus, the birth of a paralogous odourant receptor can change the tuning of the peripheral olfactory system. See you there!
Posted on: Fri, 10 Oct 2014 06:50:32 +0000
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