Evolution is a continuous process rather than a sudden change. This continuous phenomenon of acquiring unique characteristics is what split humans from chimpanzees around 4 to 6 million years ago. Is the same process of Evolution now leading the human lineage towards giving rise to the advanced species? What is guiding us on this path of Evolution?
According to the latest study, ‘microgenes’ could be the answer for how organisms acquire species-specific characters and eventually evolve.
What are Microgenes?
Scientists have identified 155 tiny new genes that arose from the non-coding DNA region. Due to their small size, these genes went undiscovered for so many years. Where a normal human gene sizes up to 10 to 15000 base pairs on average, these ‘microgenes’ are of size lesser than 300 nucleotides.
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In a 2020 study, hundreds of functional sORFs were found present in both coding and non-coding regions of the human genome. Nikolaos Vakirlis, the lead scientist of the present study, and his team used this 2020 study data and scanned human and vertebrate DNAs for functional microgenes that produced proteins.
The team profiled 155 microgenes that all vertebrates share, out of which 44 were crucial for cell growth, 3 have disease markers for disorders like muscular dystrophy, retinitis pigmentosa, and Alazami syndrome, and 1 microgene associated with human heart tissue that appeared when human and chimpanzees split from gorillas 7 to 9 million years ago.
Role of Microgenes in Evolution
Traditionally, new genes were thought to appear by duplication or mutation in the existing genes. But microgenes are found to have emerged afresh from the non-coding regions of DNA. Only 1% of our DNA is made up of protein-coding genes the rest 99 percent do not code for any proteins, thus called non-coding regions and were previously regarded as ‘junk’ DNA.
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Interestingly, these non-coding region erupted microgenes code for ‘proto-proteins’ or tiny proteins that organisms are beginning to try out. If these proteins turn out to be useful for them, these genes may get permanently fixed in the genome over time otherwise may get discarded. This is how evolution works on the molecular level.
Using the known human and vertebrate phylogenetic information, scientists predicted the phylogenetic link between the sORFs and estimated when new microgenes had arisen throughout evolutionary history. According to them, microgenes are the potential route for evolution as they might explain how humans acquired human-specific attributes as well as how other organisms gained their species-specific characteristics.
There could be more such microgenes that are yet to be discovered and perhaps more that are linked to diseases. A lot of health-related information might get uncovered by their discovery leading to the development of therapeutic methods targetting sORFs.
This work was published in the journal Cell Reports.