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Free keywords:
Animals
Behavior, Animal/physiology
Calcium Channels/genetics/*isolation & purification
Cloning, Molecular
DNA, Complementary/analysis/genetics
Drosophila Proteins/genetics/*isolation & purification
Drosophila melanogaster/cytology/genetics/*metabolism
Insect Proteins/genetics/*isolation & purification
Ion Channels/genetics/*isolation & purification
Larva/cytology/genetics/*metabolism
Molecular Sequence Data
Mutation/genetics
Nervous System/cytology/metabolism
Neurons, Afferent/cytology/metabolism
Nociceptors/cytology/*metabolism
Pain/genetics/*metabolism
Phylogeny
Physical Stimulation
Sequence Homology, Amino Acid
Sequence Homology, Nucleic Acid
Transient Receptor Potential Channels
Abstract:
We describe a paradigm for nociception in Drosophila. In response to the touch of a probe heated above 38 degrees C, Drosophila larvae produce a stereotypical rolling behavior, unlike the response to an unheated probe. In a genetic screen for mutants defective in this noxious heat response, we identified the painless gene. Recordings from wild-type larval nerves identified neurons that initiated strong spiking above 38 degrees C, and this activity was absent in the painless mutant. The painless mRNA encodes a protein of the transient receptor potential ion channel family. Painless is required for both thermal and mechanical nociception, but not for sensing light touch. painless is expressed in peripheral neurons that extend multiple branched dendrites beneath the larval epidermis, similar to vertebrate pain receptors. An antibody to Painless binds to localized dendritic structures that we hypothesize are involved in nociceptive signaling.
