Abstract
Ion channels provide the molecular bases for diverse physiological phenomena, including neuron function, respiration, absorption, secretion, and the osmotic and volume regulation of body fluids. Despite recent identification of the molecular nature and biophysical mechanisms of a wide variety of ion channels, there still remains a gap between the molecular properties of ion channels and their macroscopic physiological functions. Ascidians are marine sessile invertebrates, but the initial stage in their metamorphic life cycle, the tadpole larva, has a body form with many deep similarities to vertebrates. The larval nervous system, both dorsal and tubular, consisting of less than 100 neurons, underlies undulatory swimming. The whole genome of Ciona intestinalis, one of ascidians, has recently been sequenced. With the background provided by findings from classical physiology, when molecular tools of gene knockdown are combined with this recent flood of genomic information, C. intestinalis provides a unique opportunity to link molecular information of ion channel to physiology of whole organism. In this study, we construct a preliminary version of ion channel database of C. intestinalis based on genome information, gene expression profiles and functional expression. We summarize the repertory of the putative ion channel genes and their phylogenetic relationship with the gene sets of Chaenorhabditis elegans, Drosophila melanogaster, and the human genomes. [Jpn J Physiol 55 Suppl:S131 (2005)]
