Decyl-thio-trifluoropropanone, a competitive inhibitor of moth pheromone receptors.
An earlier study (Pophof 1998) showed that the esterase inhibitor decyl-thio-trifluoropropanone inhibited the responses of two receptor neurons of the moth Antheraea tuned to straight-chain pheromone components, an acetate and an aldehyde, respectively. Here we report that decyl-thio-trifluoropropanone also inhibited the responses of two pheromone receptor neurons of Bombyx mori to bombykol and bombykal. In contrast, decyl-thio-trifluoropropanone activated receptor neurons of the moth Imbrasia cyrtherea tuned to the pheromone component (Z)-5-decenyl 3-methyl-butanoate. However, decyl-thio-trifluoropropanone did not affect the responses of two receptor neurons of B. mori females specialized to the plant volatiles benzoic acid and linalool, respectively. These results indicate that decyl-thio-trifluoropropanone, besides inhibiting the sensillar esterase, interferes with proteins involved specifically in the excitation of pheromone receptor neurons. In binding studies with radiolabelled decyl-thio-trifuoroproparopnone, the inhibitor was bound by the pheromone-binding protein of A. polyphemus. However, the amount of decyl-thio-trifluoropropanone causing response inhibition was 300 times lower than the amount of pheromone-binding protein present in the sensilla. Since the amount of decyl-thio-trifluoropropanone adsorbed corresponded to about the maximum number of receptor molecules calculated per sensillum, we expect that decyl-thio-trifluoropropanone, probably in complex with pheromone-binding protein, competitively inhibits the pheromone receptor molecules.
Pophof
B
B
Max-Planck-Institut für Verhaltensphysiologie Seewiensen, Starnberg, Germany. pophof@mpi-seewiesen.mpg.de
Gebauer
T
T
Ziegelberger
G
G
D000818:Animals; D001667:Binding, Competitive; D012831:Bombyx / Q000502:physiology*; D002628:Chemoreceptor Cells / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D007659:Ketones / Q000494:pharmacology*; D009474:Neurons / Q000502:physiology; D010675:Pheromones; D011485:Protein Binding; D012903:Smell / Q000502:physiology*
D007659:Ketones; D010675:Pheromones