Homogeneously Staining Regions (HSR) in Chromosome 1 of the House Mouse: Synapsis and Recombination at Meiosis

Nikita Y. Torgunakov, Elena A. Kizilova, Tatyana V. Karamysheva, Lyubov P. Malinovskaya, Tatiana I. Bikchurina, Pavel M. Borodin

Research output: Contribution to journalArticlepeer-review

Abstract

Amplified sequences constitute a large part of mammalian genomes. A chromosome 1 containing 2 large (up to 50 Mb) homogeneously staining regions (HSRs) separated by a small inverted euchromatic region is present in many natural populations of the house mouse (Mus musculus musculus). The HSRs are composed of a long-range repeat cluster, Sp100-rs, with a repeat length of 100 kb. In order to understand the organization and function of HSRs in meiotic chromosomes, we examined synapsis and recombination in male mice hetero- and homozygous for the HSR-carrying chromosome using FISH with an HSR-specific DNA probe and immunolocalization of the key meiotic proteins. In all homozygous and heterozygous pachytene nuclei, we observed fully synapsed linear homomorphic bivalents 1 marked by the HSR FISH probe. The synaptic adjustment in the heterozygotes was bilateral: the HSR-carrying homolog was shortened and the wild-type homolog was elongated. The adjustment was reversible: desynapsis at diplotene was accompanied by elongation of the HSRs. Immunolocalization of H3K9me2/3 indicated that the HSRs in the meiotic chromosome retained the epigenetic modification typical for C-heterochromatin in somatic cells. MLH1 foci, marking mature recombination nodules, were detected in the proximal HSR band in heterozygotes and in both HSR bands of homozygotes. Unequal crossing over within the long-range repeat cluster can cause variation in size of the HSRs, which has been detected in the natural populations of the house mouse.

Original languageEnglish
Pages (from-to)14-22
Number of pages9
JournalCytogenetic and Genome Research
Volume161
Issue number1-2
Early online date16 Mar 2021
DOIs
Publication statusPublished - May 2021

Keywords

  • Insertion
  • Inversion
  • MLH1
  • Synaptic adjustment
  • Synaptonemal complex
  • Multigene Family
  • Cell Nucleus/metabolism
  • Epigenesis, Genetic
  • Male
  • Recombination, Genetic
  • Karyotyping
  • Female
  • Chromosome Banding
  • Mice, Inbred C57BL
  • In Situ Hybridization, Fluorescence
  • Chromosome Mapping
  • Meiosis
  • DNA/genetics
  • Homozygote
  • Animals
  • Chromosome Aberrations
  • Heterozygote
  • Mice
  • Spermatocytes/cytology
  • Histones/genetics

OECD FOS+WOS

  • 1.06.DR CELL BIOLOGY
  • 1.06.CQ BIOCHEMISTRY & MOLECULAR BIOLOGY
  • 1.06.KM GENETICS & HEREDITY
  • 1.06 BIOLOGICAL SCIENCES

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