title: Extensive length variation in the ribosomal DNA intergenic spacer of yellow perch (Perca flavescens).
abstract: The intergenic spacer (IGS) is located between ribosomal RNA (rRNA) gene copies. Within the IGS, regulatory elements for rRNA gene transcription are found, as well as a varying number of other repetitive elements that are at the root of IGS length heterogeneity. This heterogeneity has been shown to have a functional significance through its effect on growth rate. Here, we present the structural organization of yellow perch (Perca flavescens) IGS based on its entire sequence, as well as the IGS length variation within a natural population. Yellow perch IGS structure has four discrete regions containing tandem repeat elements. For three of these regions, no specific length class was detected as allele size was seemingly normally distributed. However, for one repeat region, PCR amplification uncovered the presence of two distinctive IGS variants representing a length difference of 1116 bp. This repeat region was also devoid of any CpG sites despite a high GC content. Balanced selection may be holding the alleles in the population and would account for the high diversity of length variants observed for adjacent regions. Our study is an important precursor for further work aiming to assess the role of IGS length variation in influencing growth rate in fish.
authors: a Département des sciences de l'environnement, Université du Québec à Trois-Rivières, Trois-Rivières, QC G9A 5H7, Canada.
authors: Bidénam
authors: B
authors: Kakou
authors: b Department of Biological Sciences, Université de Montréal, Montréal, QC H3C 3J7, Canada.|c GRIL - Groupe de recherche interuniversitaire en limnologie et en environnement aquatique.
authors: Bernard
authors: B
authors: Angers
authors: a Département des sciences de l'environnement, Université du Québec à Trois-Rivières, Trois-Rivières, QC G9A 5H7, Canada.|c GRIL - Groupe de recherche interuniversitaire en limnologie et en environnement aquatique.
authors: Hélène
authors: H
authors: Glémet
mesh_terms: D000818:Animals; D021903:DNA, Ribosomal Spacer / Q000235:genetics*; D014644:Genetic Variation; D010471:Perches / Q000235:genetics*; D012045:Regulatory Sequences, Nucleic Acid; D017422:Sequence Analysis, DNA
chemical_list: D021903:DNA, Ribosomal Spacer
keywords: IGS; Perca flavescens; gènes d’ARNr; rRNA genes; repetitive elements; spacer length variants; variants de longueur de l’espaceur; élements répétés