Out of patterns, the euchromatic B chromosome of the grasshopper Abracris flavolineata is not enriched in high-copy repeats

Milani, Diogo, Ruiz-Ruano, Francisco J., Camacho, Juan Pedro M. and Cabral-de-Mello, Diogo C. (2021) Out of patterns, the euchromatic B chromosome of the grasshopper Abracris flavolineata is not enriched in high-copy repeats. Heredity. ISSN 0018-067X

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Abstract

In addition to the normal set of standard (A) chromosomes, some eukaryote species harbor supernumerary (B) chromosomes. In most cases, B chromosomes show differential condensation with respect to A chromosomes and display dark C-bands of heterochromatin, and some of them are highly enriched in repetitive DNA. Here we perform a comprehensive NGS (next-generation sequencing) analysis of the repeatome in the grasshopper Abracris flavolineata aimed at uncovering the molecular composition and origin of its B chromosome. Our results have revealed that this B chromosome shows a DNA repeat content highly similar to the DNA repeat content observed for euchromatic (non-C-banded) regions of A chromosomes. Moreover, this B chromosome shows little enrichment for high-copy repeats, with only a few elements showing overabundance in B-carrying individuals compared to the 0B individuals. Consequently, the few satellite DNAs (satDNAs) mapping on the B chromosome were mostly restricted to its centromeric and telomeric regions, and they displayed much smaller bands than those observed on the A chromosomes. Our data support the intraspecific origin of the B chromosome from the longest autosome by misdivision, isochromosome formation, and additional restructuring, with accumulation of specific repeats in one or both B chromosome arms, yielding a submetacentric B. Finally, the absence of B-specific satDNAs, which are frequent in other species, along with its euchromatic nature, suggest that this B chromosome arose recently and might still be starting a heterochromatinization process. On this basis, it could be a good model to investigate the initial steps of B chromosome evolution.

Item Type: Article
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: LivePure Connector
Date Deposited: 21 Sep 2021 01:35
Last Modified: 30 Sep 2021 16:52
URI: https://ueaeprints.uea.ac.uk/id/eprint/81462
DOI: 10.1038/s41437-021-00470-5

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