Meeting Abstract

69.3  Friday, Jan. 6  Algal, nuclear-encoded gene sequences are present in the transcriptome of the kleptoplastic sea slug, Elysia chlorotica- Further evidence for horizontal gene transfer CURTIS, N.E.*; FANG, X.; JIANG, X.; SCHWARTZ, J.A.; PIERCE, S.K.; Univ. of South Florida, Tampa; Beijing Genomics Institute-Shenzhen, China; Beijing Genomics Institute-Shenzhen, China; Univ. of South Florida, Tampa; Univ. of South Florida, Tampa

Digestive cells of the opisthobranch sea slug, Elysia chlorotica, sequester chloroplasts from the heterokont alga, Vaucheria litorea. The chloroplasts continue to photosynthesize for as long as 10 months in the absence of any additional algal food. Previously, 11 nuclear-encoded algal genes have been found using PCR in genomic DNA of adult slugs and veliger larvae; the latter do not contain symbiotic plastids. Here we report that a partial analysis of the E. chlorotica transcriptome (Illumina HiSeq 2000) has revealed 101 V. litorea chloroplast genome protein coding genes, and of greater importance, 111 transcripts matching 52 V. litorea nuclear-encoded genes. Many of these transcripts encode gene products used in photosynthesis and plastid maintenance. The rarity of these algal matching transcripts suggests that, unlike in the alga, the expression rate of the transferred genes in the slug is low. These results provide further evidence that many algal nuclear genes have been somehow transferred to the E. chlorotica genome. We are presently attempting to sequence the entire E. chlorotica genome to identify the full complement of genes necessary to maintain this long-lived endosymbiosis. (Supported by BGI and an anonymous donor)