TY - JOUR

T1 - A new chromosome-assigned Mongolian gerbil genome allows characterization of complete centromeres and a fully heterochromatic chromosome

AU - Brekke, Thomas D

AU - Papadopulos, Alexander S. T.

AU - Julia, Eva

AU - Fornas, Oscar

AU - Fu, Beiyuan

AU - Yang, Fengtang

AU - de la Fuente, Roberto

AU - Page, Jesus

AU - Baril, Tobias

AU - Hayward, Alexander

AU - Mulley, John

N1 - © The Author(s) 2023. Published by Oxford University Press on behalf of Society for Molecular Biology and Evolution.

PY - 2023/5

Y1 - 2023/5

N2 - Chromosome-scale genome assemblies based on ultralong-read sequencing technologies are able to illuminate previously intractable aspects of genome biology such as fine-scale centromere structure and large-scale variation in genome features such as heterochromatin, GC content, recombination rate, and gene content. We present here a new chromosome-scale genome of the Mongolian gerbil (Meriones unguiculatus), which includes the complete sequence of all centromeres. Gerbils are thus the one of the first vertebrates to have their centromeres completely sequenced. Gerbil centromeres are composed of four different repeats of length 6, 37, 127, or 1,747 bp, which occur in simple alternating arrays and span 1-6 Mb. Gerbil genomes have both an extensive set of GC-rich genes and chromosomes strikingly enriched for constitutive heterochromatin. We sought to determine if there was a link between these two phenomena and found that the two heterochromatic chromosomes of the Mongolian gerbil have distinct underpinnings: Chromosome 5 has a large block of intraarm heterochromatin as the result of a massive expansion of centromeric repeats, while chromosome 13 is comprised of extremely large (>150 kb) repeated sequences. In addition to characterizing centromeres, our results demonstrate the importance of including karyotypic features such as chromosome number and the locations of centromeres in the interpretation of genome sequence data and highlight novel patterns involved in the evolution of chromosomes.

AB - Chromosome-scale genome assemblies based on ultralong-read sequencing technologies are able to illuminate previously intractable aspects of genome biology such as fine-scale centromere structure and large-scale variation in genome features such as heterochromatin, GC content, recombination rate, and gene content. We present here a new chromosome-scale genome of the Mongolian gerbil (Meriones unguiculatus), which includes the complete sequence of all centromeres. Gerbils are thus the one of the first vertebrates to have their centromeres completely sequenced. Gerbil centromeres are composed of four different repeats of length 6, 37, 127, or 1,747 bp, which occur in simple alternating arrays and span 1-6 Mb. Gerbil genomes have both an extensive set of GC-rich genes and chromosomes strikingly enriched for constitutive heterochromatin. We sought to determine if there was a link between these two phenomena and found that the two heterochromatic chromosomes of the Mongolian gerbil have distinct underpinnings: Chromosome 5 has a large block of intraarm heterochromatin as the result of a massive expansion of centromeric repeats, while chromosome 13 is comprised of extremely large (>150 kb) repeated sequences. In addition to characterizing centromeres, our results demonstrate the importance of including karyotypic features such as chromosome number and the locations of centromeres in the interpretation of genome sequence data and highlight novel patterns involved in the evolution of chromosomes.

KW - Meriones

KW - centromeres

KW - chromosome evolution

KW - genome

KW - karyotype

U2 - 10.1093/molbev/msad115

DO - 10.1093/molbev/msad115

M3 - Article

C2 - 37183864

VL - 40

JO - Molecular Biology and Evolution

JF - Molecular Biology and Evolution

SN - 0737-4038

IS - 5

M1 - msad115

ER -