title: Analysis of the secondary structure of ITS1 in Pectinidae: implications for phylogenetic reconstruction and structural evolution.
abstract: It is at present difficult to accurately position gaps in sequence alignment and to determine substructural homology in structure alignment when reconstructing phylogenies based on highly divergent sequences. Therefore, we have developed a new strategy for inferring phylogenies based on highly divergent sequences. In this new strategy, the whole secondary structure presented as a string in bracket notation is used as phylogenetic characters to infer phylogenetic relationships. It is no longer necessary to decompose the secondary structure into homologous substructural components. In this study, reliable phylogenetic relationships of eight species in Pectinidae were inferred from the structure alignment, but not from sequence alignment, even with the aid of structural information. The results suggest that this new strategy should be useful for inferring phylogenetic relationships based on highly divergent sequences. Moreover, the structural evolution of ITS1 in Pectinidae was also investigated. The whole ITS1 structure could be divided into four structural domains. Compensatory changes were found in all four structural domains. Structural motifs in these domains were identified further. These motifs, especially those in D2 and D3, may have important functions in the maturation of rRNAs.
authors.affiliation: Laboratory of Marine Genetics and Breeding, Division of Life Science and Technology, Ocean University of China, Qingdao, 266003, People's Republic of China.
authors.forename: Shi
authors.initials: S
authors.lastname: Wang
authors.forename: Zhenmin
authors.initials: Z
authors.lastname: Bao
authors.forename: Ning
authors.initials: N
authors.lastname: Li
authors.forename: Lingling
authors.initials: L
authors.lastname: Zhang
authors.forename: Jingjie
authors.initials: J
authors.lastname: Hu
mesh_terms: D000818:Animals; D001483:Base Sequence; D021903:DNA, Ribosomal Spacer / Q000737:chemistry / Q000235:genetics*; D019143:Evolution, Molecular; D009690:Nucleic Acid Conformation; D049897:Pectinidae / Q000235:genetics*; D010802:Phylogeny; D016415:Sequence Alignment / Q000662:veterinary; D017422:Sequence Analysis, DNA
chemical_list: D021903:DNA, Ribosomal Spacer