‘Junk DNA’ Used To Sort Species

Although short, miRNA sequences have been used to sort out phylogenetic relationships.

AsianScientist (Mar. 17, 2015) – Up till recently dismissed as ‘junk’, non-coding RNA has been found to be useful in revealing the relationships between different animal species. The study documenting these findings has been published in the Proceedings of the Royal Society B.

Only approximately one to three percent of the human genome encodes for what we usually call genes, segments of DNA that are translated into proteins and form the cell structure. The rest, termed non-coding DNA, was once thought to be useless ‘junk’. However, this concept has rapidly changed in recent years.

Non-coding RNAs such as microRNAs (miRNA) are now recognized as important regulators of gene expression. Now, a team of researchers led by Professor Jerome Hui from the Chinese University of Hong Kong has found another use for miRNA—to understand the evolutionary relationship between different species.

They first compared non-coding sequences between human, chimpanzee, gorilla, orangutan, and macaque, and successfully recovered the evolutionary history of human and our close relative, showing that chimpanzees share the closest common ancestor with human, followed by gorilla, orangutan, and then macaque being the more distant relatives. They have also successfully used this new method to reveal the relationships of other animals, such as the insects and nematodes.

“Everyone in the field seems to be focusing on the meaningful microRNAs themselves, and did not pay too much attention to other ‘junk’. So this discovery is fortunate. Certainly the utilization of these regions to resolve relationships as a new method is just the beginning,” Hui said.

“Understanding how they function is of extreme importance from fundamentally discover how the nature of these “dark matter”, which can potentially be useful from increasing aqua- or agricultural productions, combating pests, to diseases treatment.”

Hui and his team are now working on understanding the functional roles of these flanking miRNA regions.

The article can be found at: Kenny et al. (2015) The Phylogenetic Utility and Functional Constraint of microRNA Flanking Sequences.


Source: Chinese University of Hong Kong.
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