TY - JOUR

T1 - Homogeneously Staining Regions (HSR) in Chromosome 1 of the House Mouse: Synapsis and Recombination at Meiosis

AU - Torgunakov, Nikita Y.

AU - Kizilova, Elena A.

AU - Karamysheva, Tatyana V.

AU - Malinovskaya, Lyubov P.

AU - Bikchurina, Tatiana I.

AU - Borodin, Pavel M.

N1 - Funding Information: This research was funded by the Russian Foundation for Basic Research, grant #19-04-00021, and by the Ministry of Science and Higher Education of the Russian Federation grants #0324-2019-0042 and #2019-0546 (FSUS-2020-0040). The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results. Publisher Copyright: © 2021 S. Karger AG. All rights reserved. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

PY - 2021/5

Y1 - 2021/5

N2 - 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.

AB - 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.

KW - Insertion

KW - Inversion

KW - MLH1

KW - Synaptic adjustment

KW - Synaptonemal complex

KW - Multigene Family

KW - Cell Nucleus/metabolism

KW - Epigenesis, Genetic

KW - Male

KW - Recombination, Genetic

KW - Karyotyping

KW - Female

KW - Chromosome Banding

KW - Mice, Inbred C57BL

KW - In Situ Hybridization, Fluorescence

KW - Chromosome Mapping

KW - Meiosis

KW - DNA/genetics

KW - Homozygote

KW - Animals

KW - Chromosome Aberrations

KW - Heterozygote

KW - Mice

KW - Spermatocytes/cytology

KW - Histones/genetics

UR - http://www.scopus.com/inward/record.url?scp=85102819715&partnerID=8YFLogxK

U2 - 10.1159/000513266

DO - 10.1159/000513266

M3 - Article

C2 - 33725692

AN - SCOPUS:85102819715

VL - 161

SP - 14

EP - 22

JO - Cytogenetic and Genome Research

JF - Cytogenetic and Genome Research

SN - 1424-8581

IS - 1-2

ER -