Meeting Abstract
Ionotropic glutamate receptors (iGluRs) are a group of transmembrane proteins involved in many biological processes, from chemically mediated neuron communication within vertebrate brains to chemosensation within insect antennae. The group of early-diverged cnidarians includes the sea anemone Exaiptasia pallida that contains an expanded diversity of genes throughout iGluR evolution and function as chemosensory receptor proteins capable of response to bacteria. An E. pallida iGluR gene has shown cyclic gene expression profiles, prompting the hypothesis that rhythmicity of chemosensory genes may be circadian. To address this hypothesis, we explored whether E. pallida iGluR2 expression is dependent on circadian rhythm or has a natural cycle with varied expression through diurnal experimentation. Prior results showed 48 hour cyclical gene expression of E. pallida iGluR2, hypothetically stemming from circadian rhythm, shown to influence cnidarian transcription including genes involved in glutamate metabolism. Five biological replicates were sampled randomly over 4 weeks during a 24-hr time period at four hour intervals to compare the expression of EpaliGluR2 between 12-hr light:12-hr dark and 12-hr dark:12-hr dark diurnal cycles. While EpaliGluR2 has conserved domains indicative of homology to the iGluR family, nucleotide substitutions in key conserved residues suggest these diverse iGluR isoforms possess differential specificities and consequently distinct functional roles, putatively in response to light. This study is the first to measure iGluR expression as a function of diurnal influence or circadian rhythm in cnidarians.
