Structural Characterization of the Internal Transcribed Spacer 2 (ITS2) of the Ribosomal DNA (rDNA) Cluster in Calyptratae (Diptera: Schizophora) and its Implications for Molecular Phylogenetic Analyses

Autor(es)

Marinho, M. A. T. ^[1] ; Azeredo-Espin, A. M. L. ^{[1, 2]} ; Zanchin, N. I. T. ^[3]

Afiliação do(s) autor(es)

^[1] Campinas State Univ UNICAMP, Lab Anim Genet & Evolut, Ctr Mol Biol & Genet Engn CBMEG, BR-13083875 Campinas, SP - Brazil

^[2] Campinas State Univ UNICAMP, Inst Biol IB, Dept Genet & Evolut DGE, BR-13083875 Campinas, SP - Brazil

^[3] Fundacao Oswaldo Cruz, Carlos Chagas Inst, Curitiba, Parana - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of Molecular Evolution; v. 76, n. 3, p. 158-171, MAR 2013.
• Citações Web of Science: 4

Resumo

The internal transcribed spacer 2 (ITS2) of the eukaryotic ribosomal DNA (rDNA) cluster plays an essential role in processing of the ribosomal RNA, which is primarily accomplished by the secondary structures acquired by the molecule after transcription. Two possible structural conformation models have been proposed for the ITS2 region, the ``ring model{''} and the ``hairpin model,{''} and the former has been widely used in many molecular phylogenetic analyses incorporating structural information available to date. To evaluate the validity of this model, in vitro transcribed ITS2 molecules from species representing the three superfamilies of the Calyptratae clade (Diptera: Schizophora), namely Cochliomyia hominivorax, Musca domestica, and Glossina morsitans, were submitted to enzymatic digestion with single- and double-stranded specific nucleases (RNases I, A, T1, and V1). The resulting fragments were analyzed by capillary electrophoresis and digestion sites were mapped in the secondary structure models which were obtained by in silico prediction with further refinement by homology comparisons. The pattern of RNA fragments generated by these RNases show a high degree of correlation to most of the predicted helix-loop regions and structural motifs. Discrepancies to the models can be explained by alternative structural conformation dynamics (in M. domestica and G. morsitans) and by higher-order factors (such as tertiary interactions) that may stabilize thermodynamically unfavored structures (in C. hominivorax). (AU)

• Processo FAPESP: 06/61217-3 - Organização e estrutura do ITS2 em Calyptratae (Diptera: Brachycera) e sua implicação em estudos genético-evolutivos em moscas causadoras de miíases da família Calliphoridae
• Beneficiário: Marco Antonio Tonus Marinho
• Modalidade de apoio: Bolsas no Brasil - Doutorado Direto