Dr. Spencer Johnston Co-Authored Article on Antarctic Midge Genome

The adult stage of the Antarctic midge (Belgica antartica). Photo courtesy of Richard. E. Lee, Jr.

The adult stage of the Antarctic midge (Belgica antartica). Photo courtesy of Richard. E. Lee, Jr.

Who would have thought that there would be an insect (or any other terrestrial animal) tough enough to survive the brutal Antarctic environment?

A group of scientists including the Department’s own Dr. Spencer Johnston just published an article featured in Nature Magazine on the Antarctic midge that not only survives year round in the South Pole, but also has the smallest insect genome sequenced to date.

Led by Dr. Joanna Kelley of Washington State University, the scientists have set out to study the Antarctic midge (Belgica antartica) and how it has adapted to survive in the extreme conditions of the Antarctic.

According to the paper, the midge lives on the rocky outcrops of the Antarctic Peninsula and is the only land based animal endemic to the continent. The larvae develop slowly over two Antarctic winters and may lose up to half their body mass through dehydration with no ill effects.

The larval stage of the Antarctic midge (Belgica antartica). Photo courtesy of Richard. E. Lee, Jr.

The larval stage of the Antarctic midge (Belgica antartica). Photo courtesy of Richard. E. Lee, Jr.

Kelley’s group, which includes Johnston, studied the genome to see if it would provide clues on how the midge has evolved to cope with the extreme Antarctic environment. a

The group found out that the insect has the smallest insect genome discovered to date, with 99 million base pairs, as compared to the next smallest genomes, 104.7 million base pairs in the body louse and the 108 million base pairs of the parasitic twisted-wing insect (Strepsiptera:Myrmecolacidae).

Other unusual adaptations include winglessness, plus extreme cold and salinity tolerance, which allow the insect to endure high winds, exposure to salt, and of course extremes of temperature.

Johnston said it was a surprise to find that the midges somehow cope with these extreme conditions by using less genetic information, rather than more. Now, the goal is to explain the ways in which the environment has helped make the genome more efficient, selecting the right DNA elements.

It was a surprise to the research group to discover how small and compact the insect’s genome was; now they have to learn how this relates to coping with the harsh environment of the region.

“It does not cope by using more information – It copes with the same or less,” Dr. Johnston said. Even though the midge only had 99 million base pairs, the midge has around 13,500 genes, which is similar to other flies in the family. “This lends credence to the idea of Junk DNA in most genomes and suggests that the extreme environment has selected against the selfish DNA elements (Junk DNA) that bloat the genome of most of the higher organisms.

Johnston also said, “The big questions we are asking are, ‘What is essential information? What if anything is Junk DNA?’ Can manipulation of the total amount of DNA (something we do not do now) increase productivity and increase the tolerance to environmental change?’” The answers may help us find ways to adapt organisms to the changing environment and better understand the architecture of the genome and the effects of selection on that genome architecture.

The article is available in Nature by viewing at the following address: http://www.nature.com/ncomms/2014/140812/ncomms5611/full/ncomms5611.html

Comments are closed.