For water bears resilience is tucked in their DNA, say researchers looking to understand how tardigrades survive freezing, boiling and the void of space.
Commonly known as water bears, tardigrades are one of the strongest organisms out there. The microscopic creatures can successfully withstand scorching heat, literally freezing and coming back to life in 20 minutes after such an event. They have even been studied in the void of space which left no significant mark on the water bears.
The secret to their resilience can be found in the tardigrades’ DNA. The study revealing how much foreign DNA tardigrades posses is published in the Proceedings of the National Academy of Sciences journal. For water bears resilience is tucked in their DNA, 17.5 percent of which is foreign.
The research team composed of scientists from the University of North Carolina at Chapel Hill conducted genome sequencing on the water bears DNA. Looking for the key to the microscopic organisms’ outstanding resilience, the research team found that an extraordinary 6,000 genes are foreign. That is, 17.5 percent of water bears’ DNA is foreign. The finding makes tardigrades the absolute scientific wonder and record holder for this high percentage of foreign DNA. Typically, an organism possesses at most 1 percent foreign DNA.
Finding that tardigrades have evolved in time to incorporate so much foreign DNA took scientists by surprise. Bob Goldstein, one of the authors on the study, stated that this is the first time any organism or animal genome was found to possess this much foreign DNA. The process through which an organism acquires foreign genes is dubbed horizontal gene transfer.
The genome sequencing performed by the research team revealed 6,000 foreign genes, most of which are inherited from Archaea, fungi, bacteria or plants. The same process yielded some questions. How is it possible that the tardigrades’ DNA is so flexible as to incorporate this large of a foreign sequence, as well as how does it relate to the resilience of the water bears.
The first question couldn’t be answered accurately. However, the research team believes foreign DNA was acquired as the water bears bear the incredible ability to regenerate and repair damaged DNA in no time.
After suffering a shock, the water bears cells regenerate rapidly. In the process, the membrane and the nucleus of the cell are leaky. This is the time when the cell is highly permeable and permits foreign DNA and large molecules to enter.
Photo Credits: Wikimedia