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Expression of 5S rDNA multigene family in the genome of freshwater stingrays: an evolutionary approach

Grant number: 12/02540-0
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): May 01, 2012
Effective date (End): October 31, 2012
Field of knowledge:Biological Sciences - Genetics
Principal Investigator:Danillo Pinhal
Grantee:Helder Elias da Silva
Home Institution: Instituto de Biociências (IBB). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil


In higher eukaryotes, the 5S ribosomal multigene family (5S rDNA) consists of tandemly arrayed repeated units each one composed by a coding region (5S rRNA gene) and a non-transcribed spacer (NTS). It is already known that the distribution of 5S rDNA is highly conserved among related species, although several intra-and inter genomic variants of 5S rDNA units have been detected. These variants are arranged in two main classes, resulting from differences in the size and sequence of NTSs. However, in Elasmobranchii (sharks and rays), besides variations in NTSs, two distinct classes of 5S rRNA genes were recognized. These variable classes are thought to be a result of the intense genome dynamics of the Elasmobranchii group. Although the organization of the 5S rDNA classes is well known for several species, available data was mainly focused on chromosomal and nucleotide analyses. By contrast, studies on the expression and function of 5S rDNA are surprisingly scarce. Aiming to contribute to the knowledge of the evolutionary dynamics and functionality of the different 5S rDNA classes, we propose the analysis of the 5S rRNA genes expression profile in the freshwater stingrays Potamotrygon motoro and P.falknerii. The results generated by the functional analysis of 5S rDNA in this basal group can provide significant contributions towards the understanding of (1) the genome evolution and (2) the dynamics of multigene families in the genome of fish and other vertebrates, especially through the combination of structural and functional analysis of 5S rDNA arrays of these organisms. (AU)