Scientists uncover the cellular mechanisms that enable genes to produce different forms of RNA and proteins depending on the evolutionary group
Researchers at the Institute for Integrative Systems Biology (I2SysBio), a joint centre of the University of Valencia (UV) and the Spanish National Research Council (CSIC), have studied the effects of alternative splicing – a cellular mechanism that allows a single gene to generate different forms of RNA and proteins – across different species, with the aim of improving our overall understanding of genomic architecture and the evolution of life forms. The results, published in the journal eLife, reveal clear differences between unicellular organisms and mammals and birds.
16 de january de 2026
Splicing is a process through which living organisms can increase their biological complexity without increasing the number of genes. The study concludes that this mechanism varies across different clades (groups formed by a species and all its descendants, constituting a single phylogenetic branch).
The research explains that single-celled organisms display minimal splicing activity, whereas mammals and birds exhibit high levels of this process. In both taxonomic groups, splicing activity is closely associated with the amount of coding DNA sequences present within genes.
“One of the most important findings in genomic evolution is that the complexity of living beings does not increase at the same rate as the amount of coding DNA”, explains Vicente Arnau, researcher at I2SysBio and professor in the Department of Computer Science at the University of Valencia.
Andrés Moya, professor in the Department of Genetics and researcher at I2SysBio, adds: “This cellular process reflects a finely regulated mechanism in clades such as mammals and birds. The research shows that alternative splicing levels are strongly associated with genomic architecture, particularly with the proportion of coding DNA sequences within genes”.
The study, which also involved the Foundation for the Promotion of Health and Biomedical Research of the Valencian Community (FISABIO) and the Epidemiology and Public Health area of the Biomedical Research Networking Centre (CIBERESP), analysed approximately 1,500 species from the major taxonomic groups of the tree of life. The aim was to investigate the reorganisation of genomic architecture throughout evolution and the emergence of complex multicellular organisms.
The novel method developed to measure and quantify alternative splicing at the genomic scale provides a single value per species and, for the first time, allows a direct comparison between genome composition and the complexity of this cellular process across different species. Overall, alternative splicing is negatively correlated with the proportion of coding DNA in genes and reaches its highest values in genomes in which intergenic sequences account for around 50%.
Article reference: Rebeca de la Fuente, Wladimiro Dı́az-Villanueva, Vicente Arnau, Andrés Moya (2025) «Alternative splicing across the tree of life». eLife 13: RP94802. https://doi.org/10.7554/eLife.94802.3