DIFFERENTIAL PATTERNS OF EXPRESSION OF 2 NOVEL INVERTEBRATE (LYMNAEA-STAGNALIS) IONOTROPIC GLUTAMATE-RECEPTOR GENES

We report the isolation of molluscan (Lymnaea stagnalis) partial compl ementary DNAs (cDNAs) that encode two new putative glutamate-gated cat ion-channel polypeptides. These proteins, which we have named Lym-eGlu R4 and Lym-eGluR5, exhibit 56% identity to each other, and strong simi larity (56% to 61%, and 56% to 68% identity, respectively) to the corr esponding portions of vertebrate and invertebrate pha-amino-3-hydroxy- 5-methyl-4-isoxazolepropionate (AMPA)-selective (or AMPA-like) glutama te receptor (GluR) subunits. Using in situ hybridisation, we have show n that the Lym-eGluR4 and Lym-eGluR5 genes are both transcribed in all 11 central ganglia of the molluscan nervous system; however, their pa tterns of expression are quite different. Interestingly, the Lym-eGluR 5 mRNA is present in an identifiable neuron (RPeD1), within the right pedal ganglion, that has recently been shown to possess a GluR that ca n be readily activated by L-glutamate, quisqualic acid and kainic acid .