Meeting Abstract

P3-208  Tuesday, Jan. 6 15:30  Multiplicity of Na_V1 Genes in a Crustacean Subclass, the Copepoda HARTLINE, D.K.*; LENZ, P.H.; RONCALLI, V.; Univ. of Hawaii at Manoa; Univ. of Hawaii at Manoa; Univ. of Hawaii at Manoa danh@pbrc.hawaii.edu http://www.pbrc.hawaii.edu/~danh

Vertebrate voltage-gated sodium channels (Na_Vs) are characterized by a multiplicity of isoforms, designated Na_V1.1 through 1.9 in addition to the alternatively-spliced variants. These have been ascribed to multiple gene duplication events in the evolution of the line. In contrast, most invertebrates have only a single version of a clearly sodium-selective channel, homologous to the Drosophila melanogaster channel designated Dm-Na_V1. A second channel, Dm-Na_V2 appears to be permeable to calcium as well as sodium. However, the transcriptome of the calanoid copepod, Calanus finmarchicus, possesses at least three distinct channels of the Na_V1 group as well as an Na_V2. One Calanus Na_V1 channel is distinctly more similar to Dm-Na_V1 than the other two and includes a large number of splice variants. Analysis of the cladoceran Daphnia pulex genome confirms the presence of only a single Na_V1 gene, suggesting that the multiplicity of Na_V1 genes may have evolved in the copepod line. We mined public databases for other arthropods and invertebrates for sodium channel sequences homologous to those of the Calanus channels. Most crustaceans surveyed, including several copepods, possessed only sequences similar to the Drosophila-like Na_V1 sequence. However the cyclopoid copepod Eucyclops serrulatus yielded a sequence homologous to a non-Dm-Na_V1 isoform (Calfi-Na_V1-III) but not one to Dm-Na_V1.