Characterization of a plasma membrane Ca 2+ ATPase expressed in olfactory receptor neurons of the moth Spodoptera littoralis

The response of insect olfactory receptor neurons (ORNs) involves an increase in intracellular Ca2+ concentration, as in vertebrate ORNs. In order to decipher the Ca2+ clearance mechanisms in insect ORNs, we have investigated the presence of a plasma membrane Ca2+ ATPase (PMCA) in the peripheral olfactory system of the moth Spodoptera littoralis. From an analysis of a male antennal expressed-sequence-tag database combined with a strategy of 5′/3′ rapid amplification of cDNA ends plus the polymerase chain reaction, we have cloned a full-length cDNA encoding a PMCA. In adult males, the PMCA transcript has been found in various tissues, including the antennae in which its presence has been detected in the sensilla trichodea, and in cultured ORNs. The PMCA gene is slightly expressed at the end of the pupal stage, reaches a maximum at emergence and is maintained at a high level during the adult period. Taken together, these results provide, for the first time, molecular evidence for the putative participation of a PMCA in signalling pathways responsible for the establishment and functioning of the insect peripheral olfactory system.