Molecular organization of the 5S rDNA gene type II in elasmobranchs.
The 5S rDNA gene is a non-coding RNA that can be found in 2 copies (type I and type II) in bony and cartilaginous fish. Previous studies have pointed out that type II gene is a paralog derived from type I. We analyzed the molecular organization of 5S rDNA type II in elasmobranchs. Although the structure of the 5S rDNA is supposed to be highly conserved, our results show that the secondary structure in this group possesses some variability and is different than the consensus secondary structure. One of these differences in Selachii is an internal loop at nucleotides 7 and 112. These mutations observed in the transcribed region suggest an independent origin of the gene among Batoids and Selachii. All promoters were highly conserved with the exception of BoxA, possibly due to its affinity to polymerase III. This latter enzyme recognizes a dT4 sequence as stop signal, however in Rajiformes this signal was doubled in length to dT8. This could be an adaptation toward a higher efficiency in the termination process. Our results suggest that there is no TATA box in elasmobranchs in the NTS region. We also provide some evidence suggesting that the complexity of the microsatellites present in the NTS region play an important role in the 5S rRNA gene since it is significantly correlated with the length of the NTS.
a Grupo de Estudios en Genética Ecología Molecular y Fisiología Animal, Universidad del Valle , Cali , Colombia.|b Fundación Colombiana para la Investigación y Conservación de Tiburones y Rayas, SQUALUS . Cali , Colombia.
Sergio I
SI
Castro
a Grupo de Estudios en Genética Ecología Molecular y Fisiología Animal, Universidad del Valle , Cali , Colombia.|b Fundación Colombiana para la Investigación y Conservación de Tiburones y Rayas, SQUALUS . Cali , Colombia.|c Canadian Institute for Advanced Research, Program in Evolutionary Biology , Department of Biochemistry and Molecular Biology , Dalhousie University , Halifax , Canada.
Jose S
JS
Hleap
a Grupo de Estudios en Genética Ecología Molecular y Fisiología Animal, Universidad del Valle , Cali , Colombia.
Heiber
H
Cárdenas
c Canadian Institute for Advanced Research, Program in Evolutionary Biology , Department of Biochemistry and Molecular Biology , Dalhousie University , Halifax , Canada.|d Department of Computer Science , Dalhousie University , Halifax , Canada.
Christian
C
Blouin
D000818:Animals; D018940:Elasmobranchii / Q000235:genetics*; D009154:Mutation; D009690:Nucleic Acid Conformation; D012341:RNA, Ribosomal, 5S / Q000737:chemistry / Q000235:genetics*; D013045:Species Specificity; D013728:Terminator Regions, Genetic; D014158:Transcription, Genetic
D012341:RNA, Ribosomal, 5S
Internal Control Region; Microsatellites; Non-transcribed Spacer; RNA secondary structure; TATA-box