Title: The 18S rRNA from Odontophrynus americanus 2n and 4n (Amphibia, Anura) reveals unusual extra sequences in the variable region V2

Author(s):  Alvares LE, Wuyts J, Van de Peer Y, Silva EP, Coutinho LL , Brison O, Ruiz IRG

Source:  GENOME 47 (3): 421-428 JUN 2004

Document Type:  Article

Language:  English

Abstract:  The nucleotide sequence of the rDNA 18S region isolated from diploid and tetraploid species of the amphibian Odontophrynus americanus was determined and used to predict the secondary structure of the corresponding 18S rRNA molecules. Comparison of the primary and secondary structures for the 2n and 4n species confirmed that these species are very closely related. Only three nucleotide substitutions were observed, accounting for 99% identity between the 18S sequences, whereas several changes were detected by comparison with the Xenopus laevis 18S sequence (96% identity). Most changes were located in highly variable regions of the molecule. A noticeable feature of the Odontophrynus 18S rRNA was the presence of unusual extra sequences in the V2 region, between helices 9 and 11. These extra sequences do not fit the model for secondary structure predicted for vertebrate 18S rRNA. Author Keywords:  Odontophrynus americanus; Amphibia; polyploidy; 18S ribosomal DNA; molecular evolution

KeyWords Plus:  SECONDARY STRUCTURE; RDNA SEQUENCES; DATABASE; PHYLOGENY; GENES; RATES

Addresses:  Ruiz IRG (reprint author), Butantan Inst, Genet Lab, Av Vital Brasil 1500, Sao Paulo, SP BR-05503900 Brazil
Butantan Inst, Genet Lab, Sao Paulo, SP BR-05503900 Brazil
Univ Sao Paulo, ESALQ, Anim Biotechnol Lab, Piracicaba, SP Brazil
State Univ Ghent, Dept Plant Syst Biol, Ghent, B-9000 Belgium
Inst Gustave Roussy, CNRS, UMR 8125, Villejuif, France

E-mail Addresses: itamruiz@usp.br

Publisher:  NATL RESEARCH COUNCIL CANADA, RESEARCH JOURNALS, MONTREAL RD, OTTAWA, ONTARIO K1A 0R6, CANADA

Subject Category:  BIOTECHNOLOGY & APPLIED MICROBIOLOGY; GENETICS & HEREDITY

IDS Number:  833PI

ISSN:  0831-2796