Molecular organization and evolution of 5S ribosomal DNA of Sphinx ligustri

  • А. П. Статна Yurii Fedkovych University of Chernivtsy, Kotsiubynski str. 2, 58012 Chernivtsi, Ukraine
  • О. В. Череватов Yurii Fedkovych University of Chernivtsy, Kotsiubynski str. 2, 58012 Chernivtsi, Ukraine
  • Р. А. Волков Yurii Fedkovych University of Chernivtsy, Kotsiubynski str. 2, 58012 Chernivtsi, Ukraine

Abstract

Aims. 5S rDNA belongs to the class of moderately repeated sequences that are organized as tandem arrays. Each repeated unit is composed of a conservative 5S rRNA coding region and a rapidly evolving intergenic spacer (IGS). Information about organization and evolution of 5S rDNA in many groups of invertebrate animals including Lepidoptera still remains very obscure. The aim of the presented study was to describe molecular organization of 5S rDNA of Privet Hawk Moth (Sphinx ligustri), a representative of the family Sphingidae. Methods. 5S rDNA repeated units were amplified by PCR, cloned in a bacterial vector and sequenced. Results. Two length variants of 5S rDNA repeated units were detected in the genome of Sphinx ligustri. Both variants contain the 5S rRNA coding region of the same length of 120 bp, but possess IGS of different sizes, 75 and 123 bp, respectively. In spite of low sequence similarity (62.7%) the longer IGS variant originated from the shorter one by duplication of a major portion of IGS. A lack of remarkable sequence similarity between IGS of different butterfly species demonstrates that the external promoter elements involved in 5S rDNA transcription initiation are not conserved in different families of Lepidoptera.

Key words: Sphingidae, Lepidoptera, 5S rDNA, molecular evolution, promoter organization.