NOR activity and repeat sequences of the paternal sex ratio chromosome of the parasitoid wasp Trichogramma kaykai

J.J.F.A. van Vugt, S. Nooijer, R. Stouthamer, J.H.S.G.M. de Jong

Research output: Contribution to journalArticleAcademicpeer-review

26 Citations (Scopus)

Abstract

Part of the male population of the wasp Trichogramma kaykai carries a B chromosome that manipulates its host sex ratio in favour of males. The only known repeat on this paternal sex ratio (PSR) chromosome is the 45S rDNA, which includes here five different internal transcribed spacer 2 (ITS2) sequences. In this report, we describe that only part of these ITS2 sequences is transcribed. The absence of transcription of some ITS2 sequences might explain the presence of multiple ITS2 sequences on the PSR chromosome since homogenization of rDNA spacers is thought to occur only in transcribed regions. Analysis of the only other known tandem repeat in Trichogramma, the Eco RI repeat, showed that it is absent from the PSR chromosome, and that the T. kaykai Eco RI repeat has 98 and 77% DNA sequence homology with the T. deion and T. brassicae Eco RI repeats, respectively. The size of the PSR chromosome measures 9 Mbp and is equal to 3.9% of the haploid T. kaykai genome. Finally, fluorescent in situ hybridization with a pool of high and moderate repetitive T. kaykai DNA (C0t-50) revealed only a very few major tandem repeats on the Trichogramma genome and only 45S rDNA on the PSR chromosome
Original languageEnglish
Pages (from-to)410-419
JournalChromosoma
Volume114
Issue number6
DOIs
Publication statusPublished - 2005

Keywords

  • repetitive dna-sequences
  • in-situ hybridization
  • b-chromosome
  • nasonia-vitripennis
  • satellite dna
  • psr chromosome
  • genome size
  • hymenoptera
  • evolution
  • gene

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