What animal can be frozen to 80 degrees Celsius for 10 years, thaw out and run around in 20 minutes? If you haven’t guessed by the photo above, it’s the very cool tardigrade, also known as the water bear.
Scientists recently sequenced their genome and found that 17% of it comes from foreign DNA, compared to most animals with about one percent of their genome coming from foreign DNA. The study, published in Proceeding of the National Academy of Sciences, showed that tardigrades obtained 6,000 foreign genes mostly from bacteria, others from plants, fungi and Archaea, by means of horizontal gene transfer. This is accomplished by swapping genetic material between species instead of inheriting it from their parents.
Scientists think this may be why tardigrades are able to withstand extreme conditions, considering that bacteria have been able to survive the Earth’s most extreme environments for billions of years. These tough “little bears” may be able to acquire foreign DNA when their DNA breaks into tiny pieces during extremely stressful conditions. The theory, once the cell rebounds from these conditions, it is a bit leaky and foreign DNA is able to enter the cell and become part of the tardigrade DNA as it repairs itself.
“We think of the tree of life, with genetic material passing vertically from mom and dad,” said Thomas Boothby, researcher from the University of North Carolina at Chapel Hill. “But with horizontal gene transfer becoming more widely accepted and more well-known, at least in certain organisms, it is beginning to change the way we think about evolution and inheritance of genetic material and the stability of genomes. So instead of thinking of the tree of life, we can think about the web of life and genetic material crossing from branch to branch. So it’s exciting. We are beginning to adjust our understanding of how evolution works.”
Want a look at these amazing, almost microscopic creatures? A simple microscope and a sample of moss from outside, and you can see these fascinating creatures. It’s a great way to introduce your kids to microscopic world. You may get a glimpse at other organism as well. Be on the look out for nematodes, ticks, and bacteria as you search through your samples. Have your kids document and draw what they find. It’s a fun science experiment for kids of all ages.
Source: UNC-Chapel Hill
Feature photograph by Elaine Anthonise