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

Autor(es)

Milani, Diogo ^[1] ; Ruiz-Ruano, Francisco J. ^{[2, 3]} ; Camacho, Juan Pedro M. ^[4] ; Cabral-de-Mello, Diogo C. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Estadual Paulista, Inst Biociencias IB, Dept Biol Geral & Aplicada, UNESP, Rio Claro, SP - Brazil

^[2] Uppsala Univ, Evolutionary Biol Ctr, Dept Organismal Biol Systemat Biol, Uppsala - Sweden

^[3] Univ East Anglia, Sch Biol Sci, Norwich Res Pk, Norwich, Norfolk - England

^[4] UGR Univ Granada, Fac Ciencias, Dept Genet, Granada - Spain

• Tipo de documento: Artigo Científico
• Fonte: HEREDITY; v. 127, n. 5 SEP 2021.
• Citações Web of Science: 0

Resumo

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. (AU)

• Processo FAPESP: 14/11763-8 - Contribuições ao entendimento da estrutura e evolução de sistemas de cromossomos sexuais utilizando como modelos espécies de gafanhotos e grilos
• Beneficiário: Diogo Cavalcanti Cabral de Mello
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 15/16661-1 - Cromossomos sexuais, cromossomos B e seus enigmas: sistemas modelo para estudos de evolução cromossômica e genômica
• Beneficiário: César Martins
• Modalidade de apoio: Auxílio à Pesquisa - Temático