Dataset Information

Patterns of nucleotide polymorphism and divergence in the odorant-binding protein genes OS-E and OS-F: analysis in the melanogaster species subgroup of Drosophila.

ABSTRACT: The Olfactory Specific-E and -F genes (OS-E and OS-F) belong to the odorant-binding protein gene family, which includes the general odorant-binding proteins and the pheromone-binding proteins. In Drosophila melanogaster, these genes are arranged in tandem in a genomic region near the centromere of chromosome arm 3R. We examined the pattern of DNA sequence variation in an approximately 7-kb genomic region encompassing the two OS genes in four species of the melanogaster subgroup of Drosophila and in a population sample of D. melanogaster. We found that both the OS-E and the OS-F gene are present in all surveyed species. Nucleotide divergence estimates would support that the two genes are functional, although they diverge in their functional constraint. The pattern of nucleotide variation in D. melanogaster also differed between genes. Variation in the OS-E gene region exhibited an unusual and distinctive pattern: (i) a relatively high number of fixed amino acid replacements in the encoded protein and (ii) a peak of nucleotide polymorphism around the OS-E gene. These results are unlikely under the neutral model and suggest the action of natural selection in the evolution of the two odorant-binding protein genes.

SUBMITTER: Sanchez-Gracia A

PROVIDER: S-EPMC1462860 | biostudies-other | 2003 Nov

REPOSITORIES: biostudies-other

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Patterns of nucleotide polymorphism and divergence in the odorant-binding protein genes OS-E and OS-F: analysis in the melanogaster species subgroup of Drosophila.

Sánchez-Gracia Alejandro A Aguadé Montserrat M Rozas Julio J

Genetics 20031101 3

The Olfactory Specific-E and -F genes (OS-E and OS-F) belong to the odorant-binding protein gene family, which includes the general odorant-binding proteins and the pheromone-binding proteins. In Drosophila melanogaster, these genes are arranged in tandem in a genomic region near the centromere of chromosome arm 3R. We examined the pattern of DNA sequence variation in an approximately 7-kb genomic region encompassing the two OS genes in four species of the melanogaster subgroup of Drosophila and ...[more]

PMID: 14668382

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Project description:Flying insects have developed a remarkably sensitive olfactory system to detect faint and turbulent odor traces. This ability is linked to the olfactory receptors class of odorant receptors (ORs), occurring exclusively in winged insects. ORs form heteromeric complexes of an odorant specific receptor protein (OrX) and a highly conserved co-receptor protein (Orco). The ORs form ligand gated ion channels that are tuned by intracellular signaling systems. Repetitive subthreshold odor stimulation of olfactory sensory neurons sensitizes insect ORs. This OR sensitization process requires Orco activity. In the present study we first asked whether OR sensitization can be monitored with heterologously expressed OR proteins. Using electrophysiological and calcium imaging methods we demonstrate that D. melanogaster OR proteins expressed in CHO cells show sensitization upon repeated weak stimulation. This was found for OR channels formed by Orco as well as by Or22a or Or56a and Orco. Moreover, we show that inhibition of calmodulin (CaM) action on OR proteins, expressed in CHO cells, abolishes any sensitization. Finally, we investigated the sensitization phenomenon using an ex vivo preparation of olfactory sensory neurons (OSNs) expressing Or22a inside the fly's antenna. Using calcium imaging, we observed sensitization in the dendrites as well as in the soma. Inhibition of calmodulin with W7 disrupted the sensitization within the outer dendritic shaft, whereas the sensitization remained in the other OSN compartments. Taken together, our results suggest that CaM action is involved in sensitizing the OR complex and that this mechanisms accounts for the sensitization in the outer dendrites, whereas further mechanisms contribute to the sensitization observed in the other OSN compartments. The use of heterologously expressed OR proteins appears to be suitable for further investigations on the mechanistic basis of OR sensitization, while investigations on native neurons are required to study the presently unknown additional mechanisms involved in OSN sensitization.

Dataset Information

Patterns of nucleotide polymorphism and divergence in the odorant-binding protein genes OS-E and OS-F: analysis in the melanogaster species subgroup of Drosophila.

Publications

Patterns of nucleotide polymorphism and divergence in the odorant-binding protein genes OS-E and OS-F: analysis in the melanogaster species subgroup of Drosophila.

Similar Datasets

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