The Antarctic midge leads a fairly simple life. The small, singles fly spends most of it’s two year life frozen in the ice of Antarctica. When the tiny insect emerges from the ice, it has about a week to mate and lay the eggs that will spawn the next generation before it dies.

The midge is also one of the few animals to live in the antarctic, one of the harshest environments in the world. During the arctic deep freeze the insects lose up to 70 percent of the water from their bodies cells.

It should come as no surprise that such an animal has unusual DNA and it appears that the most unusual thing about it is that there is not very much. New research published in the journal Nature Communications demonstrates that the Antarctic midge has only 99 million base pairs of nucleotides, making it the smallest DNA sequence of any known animal. A human, by comparison, has over 3 billion base pairs.

“It has really taken the genome down to the bare bones and stripped it to a smaller size than was previously thought possible. It will be interesting to know if other extremophiles – ticks, mites and other organisms that live in Antarctica – also have really small genomes, or if this is unique to the midge. We don’t know that yet,” said senior author David Denlinger, Distinguished Professor of entomology and of evolution, ecology and organismal biology at The Ohio State University in a statement.

The Antarctic midge appears to have achieved this small DNA sequence, in part, by scrapping what was once called “junk DNA”. These elements, once thought to serve no purpose, are now known to have important functions in gene regulation. They also appear to be important in many disease processes.

In the Antarctic environment though the midges are unlikely to encounter any kind of predator or disease.
“We don’t yet understand what the implications are of not having all that extra baggage. It seems like a good thing in many ways, but organisms do get some beneficial things from this baggage, too,” Denlinger said.

While the architecture of the Arctic midges genome is small, the researchers note that the number of functional genes is 13,500 like other flies.

The research team still isn’t sure how the reduced number of genes allow the midge to survive in the extreme Antarctic environment.