The genome (the code of life) is not just a linear sequence of letters, but is organized in the form of chromosomes and spatially packed within cells. This three-dimensional organization is fundamental, since it determines the genes that are activated and deactivated in each cell type. Comparing the sequences of the complete genome of different species allows us to study the evolutionary dynamics and the role of the genome in the speciation process.
An international team of researchers led by the Autonomous University of Barcelona (UAB) has described how the three-dimensional structure of the genome has evolved and its role in the diversification of mammals, identifying different patterns in the organization and folding of chromosomes within the nucleus. of the cells.
Researchers from the National Center for Genomic Analysis (CNAG) in Barcelona, the Center for Genomic Regulation (CRG) in Barcelona, the universities of Kent (United Kingdom) and Stellenbosch (South Africa) and the Australian universities of New Wales also participated in the study. South, Canberra and Melbourne.
‘Our work shows the dynamics of the three-dimensional organization of the genome in different mammalian species. The results suggest that the folding of the chromosomes influences the patterns of reorganization of the genome that are transmitted to the offspring and provide new interpretative keys on the mechanisms responsible for the origin of the architecture and the plasticity of the genome of the species”, points out the coordinator of the study, Aurora Ruiz-Herrera, professor in the Department of Cellular Biology, Physiology and Immunology and the Institute of Biotechnology and Biomedicine (IBB) of the UAB. “In short, we show the existence of different degrees of genome packaging in different species and its relationship with evolution.”
Two very different mammals. On the left, elephant. (Photo: Michelle Gadd/USFWS). On the right, bat. (Photo: NPS/Capitol Reef National Park)
The research team has studied the arrangement of the genome in somatic cells of various mammalian species, including mammals of African origin and marsupials. The study, carried out by comparing the genomes of different species of mammals with placenta, has allowed the reconstruction of the genome of the common ancestor shared by these species.
The analysis, carried out using massive sequencing techniques, has made it possible to identify specific patterns of chromosome folding in cells of various species. This is the case of the African elephant and the anteater among the afrotherios and the Tasmanian devil and the kangaroo among the marsupials. The study has managed to show that the specific chromosomal rearrangements of each lineage can give rise to different configurations of the three-dimensional structure of the genome.
‘We have discovered that chromosomes are not organized and arranged in the same way within the cell nucleus in all mammalian species. In fact, we have identified a very particular arrangement in marsupials that had only been described in some species of invertebrates and yeasts”, explains Lucía Álvarez González, pre-doctoral researcher at the UAB and first signatory of the work.
“This shows us that the organization of the genome in mammals, especially in the case of marsupials, is much more diverse than previously seen,” says Aurora Ruiz-Herrera.
The study opens up new avenues of research. “Studying the dynamics of genome organization in phylogenetically distant species can provide new functional and evolutionary clues, little explored up to now,” concludes Aurora Ruiz-Herrera.
The study is titled “Principles of 3D chromosome folding and evolutionary genome reshuffling in mammals”. And it has been published in the academic journal Cell Reports. (Source: UAB)