WORLD
This Extreme Antarctic Insect has the Tiniest Genome
Baku, August 13 (AZERTAC). The Antarctic midge is a simple insect: no wings, a slender black body and an adult life span of not much more than a week.
So perhaps it's fitting the bug is now on record as the owner of the tiniest insect genome ever sequenced. At just 99 million base pairs of nucleotides (DNA's building blocks), the midge's genome is smaller than that of the body louse — and far more miniscule than the human genome, which has 3.2 billion base pairs.
"It's a pretty exciting fly," Washington State University genomics researcher Joanna Kelley, who worked on the project to sequence the midge's genome, said in a statement.
The Antarctic midge (Belgica antarctica) is exciting in more ways than one. It lives most of its life in larval form, frozen in ice. It's the only true insect that lives on the Antarctic continent, and at 0.23 inches (6 millimeters) long, it actually qualifies as the largest terrestrial animal in Antarctica, according to Miami University of Ohio's Laboratory for Ecophysiological Cryobiology. All of Antarctica's other fauna are either smaller (certain ticks and mites) or live in seawater.
Antarctic midge larvae exist in a deep freeze for two winters. They can lose up to 70 percent of the water in their bodies and still survive. As adults, the midges emerge wingless. They then live only seven to 10 days, mating and eating algae and bacteria.
Antarctic midges fascinate researchers due to the insects' ability to survive massive temperature swings, high exposure to ultraviolet light and other harsh conditions. But upon sequencing the midge's genome, scientists were shocked by the small size.
"It's tiny. That was a huge surprise," Kelley said. "I was very impressed."
With 99 million base pairs, the midge's genome beats out the tiny genome of the body louse, which has 105 million base pairs, and the twisted-wing parasite (in the order Strepsiptera), which lives inside bees, wasps and roaches, and has a genome of 108 million base pairs.