Mosquito Olfactory Receptor AgOR1

Malaria is caused by a protozoan parasite and is transmitted from person to person by mosquitoes in the genus Anopheles.When a mosquito bites an infected person, it picks up red blood cells with the sexual stages of the parasite, which then reproduce in the mosquito. The mosquito then transmits the infective stages of the parasite when she bites a new host. Only females are blood feeders, seeking a blood meal to support their egg production. Female mosquitoes feed almost exclusively after dark, finding their human hosts by tracking heat, carbon dioxide and sweat.

Human sweat contains a variety of pungent organic compounds, including 4-methylphenol. Female mosquitoes have receptors on their antennae that allow them to detect the presence of this compound as it wafts away from an even moderately sweaty human. The receptors are active only in females and are shut down after the female has found her host and finished feeding. A family of odorant receptors is found on the third chromosome of Anopheles gambiae. One of these is AgOR1, which reacts specifically to 4-methylphenol.

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Notes on the Music:

This piece is set as a sextet, or perhaps a triple duet, with four voices representing the single readout of the receptor sequence. The lower voices, bowed and plucked strings, represent the more nonpolar amino acids, while the higher voices, higher strings and oboe, reprosent the more polar amino acids. Overlaid on this quartet is a glockenspiel duet, which enters to play the seven transmembrane regions of this receptor protein. Both the amino acids and their encoding DNA are heard in the transmembrane sections. The piece ends with the gradual fading out of the terminal amino acid.

This piece was composed using ArtWonk algorithmic music software from Algorithmic Arts.

References:

• Elissa A. Hallem, and others. Olfaction: Mosquito receptor for human-sweat odorant.
  Nature 427 (15 January 2004): 212 - 213.
• Fox, A., and others. Candidate odorant receptors from the malaria vector mosquito Anopheles gambiae and evidence of down-regulation in response to blood feeding. Proc. Natl Acad. Sci. USA 98 (4 December 2001): 14693–14697.