Chromosomal Mapping of Repetitive DNAs in the Grasshopper Abracris Flavolineata Reveal Possible Ancestry of the B Chromosome and H3 Histone Spreading

PLoS One. 2013 Jun 27;8(6):e66532. doi: 10.1371/journal.pone.0066532. Print 2013.

Abstract

Supernumerary chromosomes (B chromosomes) occur in approximately 15% of eukaryote species. Although these chromosomes have been extensively studied, knowledge concerning their specific molecular composition is lacking in most cases. The accumulation of repetitive DNAs is one remarkable characteristic of B chromosomes, and the occurrence of distinct types of multigene families, satellite DNAs and some transposable elements have been reported. Here, we describe the organization of repetitive DNAs in the A complement and B chromosome system in the grasshopper species Abracris flavolineata using classical cytogenetic techniques and FISH analysis using probes for five multigene families, telomeric repeats and repetitive C0t-1 DNA fractions. The 18S rRNA and H3 histone multigene families are highly variable and well distributed in A. flavolineata chromosomes, which contrasts with the conservation of U snRNA genes and less variable distribution of 5S rDNA sequences. The H3 histone gene was an extensively distributed with clusters occurring in all chromosomes. Repetitive DNAs were concentrated in C-positive regions, including the pericentromeric region and small chromosomal arms, with some occurrence in C-negative regions, but abundance was low in the B chromosome. Finally, the first demonstration of the U2 snRNA gene in B chromosomes in A. flavolineata may shed light on its possible origin. These results provide new information regarding chromosomal variability for repetitive DNAs in grasshoppers and the specific molecular composition of B chromosomes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chromosome Mapping
  • Chromosomes, Insect*
  • Cytogenetic Analysis
  • Female
  • Grasshoppers / cytology
  • Grasshoppers / genetics*
  • Histones / genetics*
  • In Situ Hybridization, Fluorescence
  • Male
  • Meiosis
  • Multigene Family
  • RNA, Ribosomal, 18S / genetics
  • RNA, Small Nuclear / genetics
  • Repetitive Sequences, Nucleic Acid

Substances

  • Histones
  • RNA, Ribosomal, 18S
  • RNA, Small Nuclear
  • U2 small nuclear RNA

Grant support

This study was supported by Fundação de Amparo a Pesquisa do Estado de São Paulo-FAPESP (2011/19481-3, 2011/18028-3), Coordenadoria de Aperfeiçoamento de Pessoal de Nível Superior-CAPES and Conselho Nacional de Desenvolvimento Científico e Tecnológico-CNPq (475308/2011-5). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.