MOSCOW, April 7. /TASS /. Russian scientists with colleagues from China and Australia have studied RNA abundance in the mammalian brain frontal cortex of humans, chimpanzees, rhesus monkeys, and mice, Skoltech said in a press-release.
"It was found that expression of these molecules has undergone a number of drastic changes on the primate and mouse lineages, including changes during the past 6-8 Myr of human evolutionary history", says release. Gene expression differences among species constitute one of the main sources of phenotypic and functional divergence. Recent advances in sequencing technology have allowed the investigation of expression-level evolution for different RNA types.
Mid-size RNA (SnRNA and SnoRNA) is an unconventional target for evolutionary studies due to some technical questions and functional conservation among species. Functionally, most snRNAs take part in splicing. Splicing is the editing of the messenger RNA in which non-coding parts (introns) are removed and coding (exons) are joined together. Roles of all SnoRNA remain to be determined, but most of them are responsible for RNA modifications.
In this study the evolutionary conservation of snRNA and snoRNA expression was estimated. Researchers have found, that despite the presumed conservation of snRNA and snoRNA functionality, their expression levels are very different.
Particular attention was paid to the SNORA29 molecule. It functions are still unknown. This RNA showed many times lower expression in human brain cortex compared with other species. So it shows 110 Myr of conservatively high expression and then 1,000-fold drop. This data suggests SNORA29 contribution to the emergence of functional features unique to humans.
Results of the international group of scientists from Russia (Skoltech,MSU,National Researc Center “Kurchatov Institute”, Institute for Information Transmission Problems, RAS) China (CAS-MPG Partner Institute for Computational Biology, Shanghai) and Australia (La Trobe University, Melbourne) were published in the journal Genome Biology and Evolution.