Evolution and function of the germline-restricted chromosome in songbirds
Metazoans typically keep the same genetic information in all body cells over their life cycle. However, some organisms show exceptions to this rule through programmed DNA elimination from the somatic cell line, as it is the case of the puzzling germline-restricted chromosome (GRC) in songbirds. Recently, it has been demonstrated that the GRC is likely present in over half of all bird species and that the zebra finch GRC is enriched in developmental genes. The latter constitutes a novel mechanism for germline-specific gene expression in multicellular organisms, which is of significant relevance to fields as genomics, developmental biology, ecology or even cancer research. However, it remains mysterious how the GRC affects differential gene expression between tissues, the genomic divergence between species, and the determination of cell fate between germline and soma. To elucidate this, we will first perform multiplatform sequencing and high-quality assembly of the GRC in the zebra finch. Then, by comparing somatic and germline genomes from many bird species to infer the evolutionary trajectories of the GRC, we will determine its most ancient and, therefore, important genes. Finally, we will perform a functional analysis to elucidate the role of these genes in primordial germ cells and the early transmission in embryos. Recent technological advances in sequencing, bioinformatics and developmental biology provide us now with a unique moment to perform the proposed multi-omics analyses. Successful and high-quality implementation will be ensured by the extensive experience of the fellow in cytogenetics and genomics of supernumerary chromosomes as well as in developmental biology in zebrafish. In addition, the host lab is expert in cutting-edge multiplatform genomics techniques and has a multidisciplinary network of collaborators, and the secondment partner is expert in experimental biology with zebra finch embryos and primordial germ cell cultures.