PgmNr P2055: Catching de novo genes as they arise in natural populations.

Authors:
E. Durand; I. Gagnon-Arsenault; L. Nielly-Thibault; G. Charron; C. R. Landry


Institutes
Institut de Biologie Intégrative et des Systèmes, Département de Biologie, PROTEO, Pavillon Charles-Eugène-Marchand, 1030 avenue de la Médecine - Université Laval - Québec (QC) G1V 0A6, Canada.


Abstract:

The emergence of new genes is a driving engine for the acquisition of adaptive innovations. New genes may arise de novo from previously non-genic regions or from pre-existing gene structures such as gene duplication. The de novo origination is the initial source of genetic novelties and comparative studies between and within species brought to light the potential contribution of intergenic regions in this process. De novo gene origination involves the acquisition of an intergenic ORF by mutations conferring a gain of in frame start and stop codons, and regulatory sites to allow its transcription and translation. Here we explore the dynamics of recently emerging de novo genes in natural Saccharomyces paradoxus populations. We first characterized intergenic ORF diversity in 24 S. paradoxus strains, sampled in North America, that are structured in 3 lineages. These lineages are used to investigate an on ongoing speciation event, making them a perfect model in the context of recently emerging genes and their role in adaptation and potentially speciation [1]. We annotated intergenic ORFs and classified them according to the conservation of their positions. In total, 73,657 ORF families were identified: some (2%) are conserved between S. cerevisiae and S. paradoxus while 28 and 8% are fixed and specific to S. cerevisiae or S. paradoxus respectively. Interestingly, the remaining 62% of intergenic ORFs still segregate within and among the S. paradoxus lineages. This diversity illustrates the power of using population data to investigate the emergence of de novo genes from scratch, which is expected to be rare. We are now characterizing the coding potential of intergenic ORFs at the transcriptional and translational levels to compare the rate of transcription/translation gain or loss versus ORF birth and death. Our results show that intergenic regions contain a large pool of ORFs readily available for natural selection to draw from during species formation.

Leducq JB. et al. (2016) Speciation driven by hybridization and chromosomal plasticity in a wild yeast. Nature Microbiol. 1: 15003. doi:10.1038/nmicrobiol.2015.3.