NEW DELHI, Apr 29:
Scientists have found that at least 10 per cent of the human genome is highly conserved across species, with many of these regions occurring outside of protein-coding genes.
They also found that more than 4,500 elements are almost perfectly conserved across more than 98 percent of the species studied. The findings are part of a series of studies published in the journal Science by 150 researchers across seven time zones, including the US and Sweden, forming the Zoonomia Project. Scientists with the Zoonomia Project have been cataloguing the diversity in mammalian genomes by comparing DNA sequences from 240 species that exist today, from the aardvark and the African savanna elephant to the yellow-spotted rock hyrax and the zebu.
This study found that most of the conserved regions, which have changed more slowly than random fluctuations in the genome, are involved in embryonic development and regulation of ribonucleic acid (RNA) expression.
The researchers said that regions that changed more frequently shaped an animal’s interaction with its environment, such as through immune responses or the development of its skin.
The researchers also pinpointed parts of the genome linked to a few exceptional traits in the mammalian world, such as extraordinary brain size, superior sense of smell, and the ability to hibernate during the winter.
With an eye toward preserving biodiversity, the researchers found that mammals with fewer genetic changes at conserved sites in the genome were at greater risk for extinction.
They say that even having just one reference genome per species could help scientists identify at-risk species, as less than 5 per cent of all mammalian species have reference genomes, though more work is needed to develop these methods.
Through this and several other papers, the Zoonomia team demonstrated how comparative genomics can not only shed light on how certain species achieve extraordinary feats, but also help scientists better understand the parts of our genome that are functional and how they might influence health and disease.
In these studies, the researchers identified regions of the genomes, sometimes just single letters of DNA, that are most conserved, or unchanged, across mammalian species and millions of years of evolution – regions that are likely biologically important.
They also found part of the genetic basis for uncommon mammalian traits such as the ability to hibernate or sniff out faint scents from miles away. And they pinpointed species that may be particularly susceptible to extinction, as well as genetic variants that are more likely to play causal roles in rare and common human diseases.
The findings come from analyses of DNA samples collected by more than 50 different institutions worldwide, including many from the San Diego Wildlife Alliance (US), which provided many genomes from species that are threatened or endangered. (PTI)
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