title: Two new group-II twintrons in the Euglena gracilis chloroplast are absent in basally branching Euglena species.
abstract: Studies of the phylogeny and chloroplast intron content of selected Euglena species have led to insights in our understanding of the timing of intron acquisition. In the current study, two new twintrons, found in E. gracilis, have been characterized by the analysis of partially spliced pre-mRNAs. Intron 1 of atpE is a 463-nt group-II intron interrupted by a second group-II intron 320 nt long. Intron 1 of psbD is also a group-II twintron with external and internal introns of 635 nt and 463 nt, respectively. The two introns composing the psbD twintron, as well as six additional group-II introns found in the E. gracilispsbD gene, are not present in several basally branching Euglena species, including E. myxocylindracea, E. stellata and E. viridis. The distribution of psbD introns in Euglena is consistent with a late evolutionary acquisition of group-II introns in this lineage.
authors.affiliation: Department of Biochemistry, University of Arizona, Tucson, AZ 85721, USA.
authors.forename: M D
authors.initials: MD
authors.lastname: Thompson
authors.forename: L
authors.initials: L
authors.lastname: Zhang
authors.forename: L
authors.initials: L
authors.lastname: Hong
authors.forename: R B
authors.initials: RB
authors.lastname: Hallick
mesh_terms: D000818:Animals; D002736:Chloroplasts / Q000235:genetics*; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000032:analysis / Q000235:genetics; D004587:Electrophoresis, Agar Gel; D005055:Euglena / Q000235:genetics*; D005056:Euglena gracilis / Q000235:genetics*; D007438:Introns; D015394:Molecular Structure; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics; D045332:Photosystem II Protein Complex; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics
chemical_list: D018076:DNA, Complementary; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D012333:RNA, Messenger