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Molecular and functional characterization of the odorant receptor2 (OR2) in the tiger mosquito Aedes albopictus.

Scialò F, Hansson BS, Giordano E, Polito CL, Digilio FA - PLoS ONE (2012)

Bottom Line: Our data indicate that AalOR2 is narrowly tuned to indole, and inhibited by (-)-menthone.In agreement with this results, these two compounds elicit two opposite effects on the olfactory-based behavior of A. albopictus larvae, as determined through a larval behavioral assay.In summary, this work has led to the cloning and de-orphaning of the first Odorant Receptor in the tiger mosquito A. albopictus.

View Article: PubMed Central - PubMed

Affiliation: Institute of Genetics and Biophysics A. Buzzati-Traverso, CNR, Naples, Italy.

ABSTRACT
In mosquitoes, the olfactory system plays a crucial role in many types of behavior, including nectar feeding, host preference selection and oviposition. Aedes albopictus, known also as the tiger mosquito, is an anthropophilic species, which in the last few years, due to its strong ecological plasticity, has spread throughout the world. Although long considered only a secondary vector of viruses, the potential of its vector capacity may constitute a threat to public health. Based on the idea that an improved understanding of the olfactory system of mosquitoes may assist in the development of control methods that interfere with their behavior, we have undertaken a study aimed at characterizing the A. albopictus Odorant Receptors. Here we report the identification, cloning and functional characterization of the AalOR2 ortholog, that represents the first candidate member of the odorant receptor (OR) family of proteins from A. albopictus. AalOR2 is expressed in the larval heads and antennae of adults. Our data indicate that A. albopictus OR2 (AalOR2) shares a high degree of identity with other mosquito OR2 orthologs characterized to date, confirming that OR2 is one of the most conserved mosquito ORs. Our data indicate that AalOR2 is narrowly tuned to indole, and inhibited by (-)-menthone. In agreement with this results, these two compounds elicit two opposite effects on the olfactory-based behavior of A. albopictus larvae, as determined through a larval behavioral assay. In summary, this work has led to the cloning and de-orphaning of the first Odorant Receptor in the tiger mosquito A. albopictus. In future control strategies this receptor may be used as a potential molecular target.

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Alignment of mosquito OR2 amino acid sequences.The multiple alignments and calculations of sequence identities and similarities were made using ClustalX (http://www.ebi.ac.uk/Tools/msa/clustalw2/) and protein Blast (http://blast.ncbi.nlm.nih.gov/Blast.cgi), respectively. Clustal notes amino acid alignments as follows: an asterisk indicates a conserved amino acid, a single dot indicates that either the size or hydropathy is conserved, and stacked dots (:) indicate that both the size and hydropathy are conserved. The GenBank accession numbers are JN400274 and JN400275 for the AalOR2 cDNA and genomic sequences, respectively.
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pone-0036538-g001: Alignment of mosquito OR2 amino acid sequences.The multiple alignments and calculations of sequence identities and similarities were made using ClustalX (http://www.ebi.ac.uk/Tools/msa/clustalw2/) and protein Blast (http://blast.ncbi.nlm.nih.gov/Blast.cgi), respectively. Clustal notes amino acid alignments as follows: an asterisk indicates a conserved amino acid, a single dot indicates that either the size or hydropathy is conserved, and stacked dots (:) indicate that both the size and hydropathy are conserved. The GenBank accession numbers are JN400274 and JN400275 for the AalOR2 cDNA and genomic sequences, respectively.

Mentions: In order to clone OR2 in Aedes albopictus we carried out RT-PCR experiments with a degenerate pair of primers designed on a multiple sequence alignment of the OR2 orthologs from Anopheles gambiae, Aedes aegypti, and Culex pipiens (see primers section). These primers were used to amplify a partial sequence of AalOR2 from cDNA prepared from manually dissected A. albopictus adult antennae. As confirmed by sequencing, we obtained a 651 bp fragment that shared a high degree of homology with its orthologs. Based on this clone, we designed additional gene-specific primers to perform RACE reactions to yield both 5′ and 3′ end AalOR2 sequences (see primers section). Finally, the amplicon obtained, 1.131 bp long, encoded a hyphothetical 376 amino acid polypeptide that was aligned with those of other OR2 sequences from A. gambiae, A. aegypti, and C. pipiens. Literature data [15], [21] show that OR2 is one of the most conserved ORs in these three mosquito species, approaching >80% identity. AalOR2 shares a 71% identity with A.gambiae, an 80% identity with C.pipiens and a 97% identity with its most evolutionarily related ortholog from A. aegypti AaeOR2 (Fig. 1). This result confirms that OR2 is highly conserved in mosquitoes, unlike other ORs for which the sequences are highly divergent. In order to obtain information on the genomic organization we performed a PCR reaction by using two external primers (5′AalOR2Fw/3′AalOR2Rv, see primer section) on genomic DNA. The amplification of a genomic clone, 1.556 bp in length, revealed that the region corresponding to the CDS of the AalOR2 gene shares a genomic organization with the corresponding region of the AaeOR2 gene. Both contain highly conserved 6 exons that are separated by 5 introns, conserved in length and in position. All exon-intron junctional sequences conform to the canonical GT-AG rule.


Molecular and functional characterization of the odorant receptor2 (OR2) in the tiger mosquito Aedes albopictus.

Scialò F, Hansson BS, Giordano E, Polito CL, Digilio FA - PLoS ONE (2012)

Alignment of mosquito OR2 amino acid sequences.The multiple alignments and calculations of sequence identities and similarities were made using ClustalX (http://www.ebi.ac.uk/Tools/msa/clustalw2/) and protein Blast (http://blast.ncbi.nlm.nih.gov/Blast.cgi), respectively. Clustal notes amino acid alignments as follows: an asterisk indicates a conserved amino acid, a single dot indicates that either the size or hydropathy is conserved, and stacked dots (:) indicate that both the size and hydropathy are conserved. The GenBank accession numbers are JN400274 and JN400275 for the AalOR2 cDNA and genomic sequences, respectively.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3351472&req=5

pone-0036538-g001: Alignment of mosquito OR2 amino acid sequences.The multiple alignments and calculations of sequence identities and similarities were made using ClustalX (http://www.ebi.ac.uk/Tools/msa/clustalw2/) and protein Blast (http://blast.ncbi.nlm.nih.gov/Blast.cgi), respectively. Clustal notes amino acid alignments as follows: an asterisk indicates a conserved amino acid, a single dot indicates that either the size or hydropathy is conserved, and stacked dots (:) indicate that both the size and hydropathy are conserved. The GenBank accession numbers are JN400274 and JN400275 for the AalOR2 cDNA and genomic sequences, respectively.
Mentions: In order to clone OR2 in Aedes albopictus we carried out RT-PCR experiments with a degenerate pair of primers designed on a multiple sequence alignment of the OR2 orthologs from Anopheles gambiae, Aedes aegypti, and Culex pipiens (see primers section). These primers were used to amplify a partial sequence of AalOR2 from cDNA prepared from manually dissected A. albopictus adult antennae. As confirmed by sequencing, we obtained a 651 bp fragment that shared a high degree of homology with its orthologs. Based on this clone, we designed additional gene-specific primers to perform RACE reactions to yield both 5′ and 3′ end AalOR2 sequences (see primers section). Finally, the amplicon obtained, 1.131 bp long, encoded a hyphothetical 376 amino acid polypeptide that was aligned with those of other OR2 sequences from A. gambiae, A. aegypti, and C. pipiens. Literature data [15], [21] show that OR2 is one of the most conserved ORs in these three mosquito species, approaching >80% identity. AalOR2 shares a 71% identity with A.gambiae, an 80% identity with C.pipiens and a 97% identity with its most evolutionarily related ortholog from A. aegypti AaeOR2 (Fig. 1). This result confirms that OR2 is highly conserved in mosquitoes, unlike other ORs for which the sequences are highly divergent. In order to obtain information on the genomic organization we performed a PCR reaction by using two external primers (5′AalOR2Fw/3′AalOR2Rv, see primer section) on genomic DNA. The amplification of a genomic clone, 1.556 bp in length, revealed that the region corresponding to the CDS of the AalOR2 gene shares a genomic organization with the corresponding region of the AaeOR2 gene. Both contain highly conserved 6 exons that are separated by 5 introns, conserved in length and in position. All exon-intron junctional sequences conform to the canonical GT-AG rule.

Bottom Line: Our data indicate that AalOR2 is narrowly tuned to indole, and inhibited by (-)-menthone.In agreement with this results, these two compounds elicit two opposite effects on the olfactory-based behavior of A. albopictus larvae, as determined through a larval behavioral assay.In summary, this work has led to the cloning and de-orphaning of the first Odorant Receptor in the tiger mosquito A. albopictus.

View Article: PubMed Central - PubMed

Affiliation: Institute of Genetics and Biophysics A. Buzzati-Traverso, CNR, Naples, Italy.

ABSTRACT
In mosquitoes, the olfactory system plays a crucial role in many types of behavior, including nectar feeding, host preference selection and oviposition. Aedes albopictus, known also as the tiger mosquito, is an anthropophilic species, which in the last few years, due to its strong ecological plasticity, has spread throughout the world. Although long considered only a secondary vector of viruses, the potential of its vector capacity may constitute a threat to public health. Based on the idea that an improved understanding of the olfactory system of mosquitoes may assist in the development of control methods that interfere with their behavior, we have undertaken a study aimed at characterizing the A. albopictus Odorant Receptors. Here we report the identification, cloning and functional characterization of the AalOR2 ortholog, that represents the first candidate member of the odorant receptor (OR) family of proteins from A. albopictus. AalOR2 is expressed in the larval heads and antennae of adults. Our data indicate that A. albopictus OR2 (AalOR2) shares a high degree of identity with other mosquito OR2 orthologs characterized to date, confirming that OR2 is one of the most conserved mosquito ORs. Our data indicate that AalOR2 is narrowly tuned to indole, and inhibited by (-)-menthone. In agreement with this results, these two compounds elicit two opposite effects on the olfactory-based behavior of A. albopictus larvae, as determined through a larval behavioral assay. In summary, this work has led to the cloning and de-orphaning of the first Odorant Receptor in the tiger mosquito A. albopictus. In future control strategies this receptor may be used as a potential molecular target.

Show MeSH
Related in: MedlinePlus