While in the big scheme of things DNA is still something we only recently found out about, a huge amount of research has gone into this subject, so it can be confidently said that experts really have a good handle on it. Even regular people know what DNA is and the very basics of how it works from watching TV shows and movies. Right?

Well, it may be that even the most advanced experts in the world don’t have as good a grasp on DNA as they once believed.

Years ago when the human genome was first mapped, scientists found a lot of genes that they thought were basically functionless. In fact, as much as 50% of our DNA was classified as having no useful function. This wasn’t exactly surprising since DNA evolves over time and it makes sense that some DNA would fall out of use after many generations.

As long as that ‘useless’ DNA didn’t make survival (or reproduction) less likely, there was no evolutionary push to have it eliminated from the genome. Or at least that is what was thought at the time.

More recently, an international group of scientists published a study in the journal Science Advances that looks specifically on a class of DNA called transposable elements, or ‘jumping genes,’ that were previously believed to be without real function.

What they found, however, is that at least one  type of these known as MER11 can actually work like genetic switches, and have a major impact on gene expression, though they don’t change the underlying DNA at all. In a statement about the work, study coauthor Fumitaka Inoue of Kyoto University said:

“Our genome was sequenced long ago, but the function of many of its parts remain unknown.”

The MER11 genes are known as LTR’s, or Long Terminal Repeat Retrotransposons, which are thought to have come from an endogenous retrovirus millions of years ago. That virus hijacked the DNA of the cells it infected in order to produce copies of its genetics. They remain in our DNA all the way down to today. The authors of the study write of these LTRs:

“The proper classification and annotation of LTR instances is critical to understanding their evolution, co-option and potential impact on the host.”

In the study, the authors looked at the MER11 sequences and broke them up into subfamilies called MER11_G1, MER11_G2, MER11_G3, and MER11_G4, based on how well they were preserved in our genomes. From there, the team can compare the subfamilies into what is termed epigenetic marks, which are chemicals that can have an impact on how proteins function, and therefore how genes behave.

Rather than changing the DNA directly, these MER11 genes can, for example, silence a gene that would otherwise be expressed.

This is a major step forward in having a more complete understanding of how DNA influences not just humans, but all organisms. Additional research will be needed to attempt to figure out which specific sequences have an impact on which proteins or traits.

While there is a long way to go, this study has turned what was thought to be ‘junk DNA’ into something surprisingly important.

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