title: Complete mitochondrial genome of the sea slug, Placida sp., contains unusual noncoding regions.
abstract: The complete sequence (14,751 bp) of the mitochondrial DNA (mtDNA) of the opisthobranch gastropod Placida sp. was determined using long PCR and genome-walking techniques. The genome contains 13 protein-coding genes (PCG), 2 ribosomal RNA (rRNA), 22 transfer RNA (tRNA) genes that are typical of metazoan mtDNA, and 2 lengthy noncoding regions with a total length of 1441 bp. All the tRNA genes have general secondary structures without reduced T or D stems. The mitochondrial gene arrangement of Placida sp. is almost identical to that of sea slugs, whereas the tRNA gene arrangement is different from other animals outside Sacoglossa in the Euthyneura. A phylogenetic analysis based on the mitochondrial genome of Euthyneura indicated that Placida sp. and Placida dendritica are closely related to Elysia chlorotica as a sister taxon, which strongly supports their close phylogenetic affinity.
authors.affiliation: Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, PR China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Fan
authors.forename: Hongjin
authors.initials: H
authors.lastname: Qiao
authors.forename: Dong
authors.initials: D
authors.lastname: Xu
authors.forename: Shaona
authors.initials: S
authors.lastname: Cao
authors.forename: Xiaowen
authors.initials: X
authors.lastname: Zhang
authors.forename: Yitao
authors.initials: Y
authors.lastname: Wang
authors.forename: Shanli
authors.initials: S
authors.lastname: Mou
authors.forename: Naihao
authors.initials: N
authors.lastname: Ye
mesh_terms: D000818:Animals; D004272:DNA, Mitochondrial / Q000235:genetics; D049851:Gastropoda / Q000145:classification / Q000235:genetics*; D015321:Gene Rearrangement; D054629:Genome, Mitochondrial; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011506:Proteins / Q000235:genetics; D012335:RNA, Ribosomal / Q000235:genetics; D012343:RNA, Transfer / Q000235:genetics
chemical_list: D004272:DNA, Mitochondrial; D011506:Proteins; D012335:RNA, Ribosomal; D012343:RNA, Transfer