Evolution of Gene Structure in Multicellular Eukaryotes

We investigated the patterns of intron conservation in eukaryotes for five different genes. The genes examined were ribosomal proteins L8, Sl4 and S17, along with elongation factor 2B and triose phosphate isomerase. 1ntron conservation for S14, S17, and triose phosphate isomerase was determined for 32 species representing the major branches of multicellular eukaryotes. For 25 conserved introns 16 were phase O,five were phase 1, and four were phase 2. Triose phosphate isomerase had five of nine conserved introns shared between plants and animals, where S14 had one of nine and Sl7 had one of seven. However, there were two plant S14 introns that could be found in single soil-living organisms from the animal branch, suggestive of horizontal transfer. Supplementary Figures are available at http://biscweb.uark. edu!drhoads/pubs/lntronsSupFigs.pdf