Potential sites of triple-helical nucleic acid formation in chromosomes of Rhynchosciara (Diptera: Sciaridae) and Drosophila melanogaster

Autor(es)

Gorab, Eduardo ^[1] ; Amabis, Jose Mariano ^[1] ; Stocker, Ann Jacob ^{[1, 2]} ; Drummond, Laura ^[1] ; Stollar, Bernard David ^[3]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Dept Genet & Biol Evolut, Inst Biociencias, BR-05508090 Sao Paulo - Brazil

^[2] Univ Melbourne, Dept Genet, Ctr Environm Stress & Adaptat Res, Parkville, Vic 3052 - Australia

^[3] Tufts Univ, Sch Med, Dept Biochem, Boston, MA 02111 - USA

• Tipo de documento: Artigo Científico
• Fonte: Chromosome Research; v. 17, n. 6, p. 821-832, Aug. 2009.
• Área do conhecimento: Ciências Biológicas - Genética
• Citações Web of Science: 11
• Assunto(s): Insetos Drosophila Ácidos nucleicos Heterocromatina Cromossomos

Resumo

Antibodies to specific nucleic acid conformations are amongst the methods that have allowed the study of non-canonical (Watson-Crick) DNA structures in higher organisms. In this work, the structural limitations for the immunological detection of DNA. RNA hybrid duplexes were examined using specific RNA homopolymers as probes for homopolymer polydeoxyadenylic acid (poly(dA)).polydeoxythymidylic acid (poly(dT))-rich regions of Rhynchosciara americana (Diptera: Sciaridae) chromosomes. Anti-DNA. RNA duplexes did not react with the complex formed between chromosomal poly(dA) and exogenous polyuridylic acid (poly(rU)). Additionally, poly(rU) prevented the detection of polyadenylic acid.poly(dT) hybrid duplexes preformed in situ. These results raised the possibility that three-stranded structures rather than duplexes were formed in chromosomal sites. To test this hypothesis, the specificity of antibodies to triple-helical nucleic acids was reassessed employing distinct nucleic acid configurations. These antibodies were raised to the poly(dA).poly(rU).poly(rU) complex and have been used here for the first time in immunocytochemistry. Anti-triplex antibodies recognised the complex poly(dA).poly(rU).poly(rU) assembled with poly(rU) in poly(dA).poly(dT)-rich homopolymer regions of R. americana chromosomes. The antibodies could not detect short triplex stretches, suggesting the existence of constraints for triple-helix detection, probably related to triplex tract length. In addition, anti-poly(dA).poly(rU).poly(rU) antibodies reacted with the pericentric heterochromatin of RNase-treated polytene chromosomes of R. americana and Drosophila melanogaster. In apparent agreement with data obtained in cell types from other organisms, the results of this work suggest that significant triple-helix DNA extensions can be formed in pericentric regions of these species. (AU)

• Processo FAPESP: 03/01053-9 - Clonagem e caracterizacao de sequencias de dna associadas aos telomeros de rhynchosciara americana.
• Beneficiário: Eduardo Gorab
• Modalidade de apoio: Auxílio à Pesquisa - Regular