PT  - JOURNAL ARTICLE
AU  - Stéphane Descorps-Declère
AU  - Guy-Franck Richard
TI  - Megasatellite formation and evolution in vertebrates
AID  - 10.1101/2021.07.19.452908
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.07.19.452908
4099  - http://biorxiv.org/content/early/2021/07/20/2021.07.19.452908.short
4100  - http://biorxiv.org/content/early/2021/07/20/2021.07.19.452908.full
AB  - Since the formation of the first proto-eukaryotes, more than 1.5 billion years ago, eukaryotic gene repertoire as well as genome complexity has significantly increased. Among genetic elements that are responsible for this increase in genome coding capacity and plasticity are tandem repeats such as microsatellites, minisatellites and their bigger brothers, megasatellites. Although microsatellites have been thoroughly studied in many organisms for the last 20 years, little is known about the distribution and evolution of mini- and megasatellites. Here, we describe the first genome-wide analysis of megasatellites in 58 vertebrate genomes, belonging to 12 monophyletic groups. We show that two bursts of megasatellite formation occurred, one after the radiation between agnatha et gnathostomata fishes and the second one later, in therian mammals. Megasatellites are frequently encoded in genes involved in transcription regulation (zinc-finger proteins) and intracellular trafficking, but also in cell membrane metabolism, reminiscent of what was observed in fungi genomes. The presence of many introns within young megasatellites suggests a model in which an exon-intron DNA segment is first duplicated and amplified before the accumulation of mutations in intronic parts partially erase the tandem repeat in such a way that it becomes detectable only in exonic regions. In addition, evidence for the genetic transfer of megasatellites between unrelated genes suggests that megasatellite formation and evolution is a very dynamic and still ongoing process in vertebrate genomes.Competing Interest StatementThe authors have declared no competing interest.