Meeting Abstract

P2.88  Friday, Jan. 4  Preliminary Analysis of the Transcriptome Sequence of Elysia chlorotica Indicates the Presence of Additional Transferred Algal Nuclear Genes SCHWARTZ, J.A.*; CURTIS, N.E.; PIERCE, S.K.; University of South Florida; University of South Florida; University of South Florida Julieaschwartz@aol.com

The sacoglossan sea slug, Elysia chlorotica (Gould) feeds on the chromophytic algae, Vaucheria litorea (C. Agardh) and sequesters chloroplasts in specialized cells lining the digestive diverticula. These chloroplasts actively photosynthesize within the slug for as long as nine months and many chloroplast proteins are synthesized while the plastid resides in the slug cell. Using PCR techniques we have demonstrated the presence of at least three nuclear-encoded, algal genes for chloroplast proteins in the mRNA and DNA of adult slugs and in the DNA in pre-hatched, un-fed veliger larvae. Thus, genes for chloroplast proteins have been transferred from the algal nucleus into the slug�s genome. To identify additional transferred genes we have sequenced about 25% of the E. chlorotica transcriptome using 454 Life Sciences high-throughput technology with a normalized E. chlorotica cDNA library, which produced approximately 10,000 contigs of at least 100bp in length. So far, BLAST analysis (tblastx) of approximately 5000 contig sequences has identified at least 25 additional transferred nuclear-encoded algal gene candidates, which we define as having a high sequence similarity to a plant entry in the database. Generally, there are few Vaucheria or other heterokont algal sequences in the database for comparison, so we are preparing the Vaucheria transcriptome for sequencing which will allow for direct comparison of the slug and algal sequences. However, these preliminary results suggest that around 200 genes may have been transferred from the alga to the slug. (supported by NSF-IBN 0315221)