Recently Discovered Tardigrade Exhibits Extraordinary Capacity for Recovery, Akin to Superheroes
Recently Discovered Tardigrade Exhibits Extraordinary Capacity for Recovery, Akin to Superheroes
Tiny, eight-legged critters resembling alien teddy bears, known as tardigrades, have an unmatched toughness among Earth's creatures. These minuscule organisms can withstand staggering radiation levels, nearly 1,000 times greater than the lethal limit for humans, and endure extreme environments that no other organism can tolerate. A newly discovered species of tardigrades, Hypsibius henanensis, reveals how it thrives in harsh circumstances by repairing DNA damage from excessive gamma radiation exposure.
There are approximately 1,500 known tardigrade species, affectionately called water bears, but their protective radiation resistance mechanisms remain a mystery. A recent study focuses on this elusive species to unravel the molecular secrets that underpin its superhuman resistance to radiation. These insights might pave the way for new methods to shield astronauts from radiation in space, thereby enhancing the potential for extended human space travel.
Lei Li, a researcher from the Chinese Academy of Science and the study's lead author, stated, "Tardigrades' extraordinary ability to withstand extreme environments offers a wealth of unexplored mechanisms of stress resistance." Further investigation into these radiation resistance mechanisms will contribute to a deeper comprehension of cellular survival under such extreme circumstances.
Scientists from the study, published in Science, decoded the tardigrade species' genome, which they discovered around six years ago in China's Henan province. When exposed to radiation, this tardigrade species activates a complex defensive system that safeguards its DNA from damage and initiates repair of any ensuing breaks.
The most renowned tardigrade defense mechanism is its capacity to enter a dormant state reminiscent of death, in which it withdraws its eight legs and curls up into a ball, depleting near its entire internal water supply. This dehydrated condition, as well as other protective measures, enables tardigrades to endure the most unfavorable conditions for decades, surviving extreme temperatures, high radiation levels, or even the vacuum of space.
The recently discovered species, Hypsibius henanensis, possesses 14,701 genes, with 30% unique to tardigrades. Through a series of experiments, scientists exposed this newly identified water bear to doses of 200 and 2,000 grays of radiation and discovered that 2,801 genes related to DNA repair, cell division, and immune responses were activated. One of these genes, TRID1, triggers a protein (53BP1) at sites of damage to assist in repairing double-strand breaks in DNA.
Hypsibius henanensis also relies on other genes to support its remarkable resilience, such as DODA1, which produces antioxidant pigments typically found in bacteria, plants, and fungi to neutralize the reactive chemicals produced by radiation exposure, and BCS1, which shields tardigrades' cells from mitochondrial damage.
According to Thomas Boothby, an assistant professor of Molecular Biology at the University of Wyoming, who was not involved in the study, "Tardigrades are found in virtually every environment on Earth, from deep-sea environments to mountain peaks. Their exceptional stress tolerance may have played a role in their extensive colonization of various biomes."
Boothby sent water bears to space in 2021 to better understand how they endure harsh conditions on the International Space Station. "Understanding tardigrade survival in space and under spaceflight conditions is crucial for developing treatments and countermeasures to combat the stresses and dysfunctions experienced by humans during prolonged spaceflight," Boothby said.
Tardigrades have captivated scientists, particularly in the context of spaceflight. Analyzing how these microscopic creatures survive in demanding environments, such as microgravity and elevated radiation levels, could provide insights into safeguarding humans from the repercussions of long-term space travel.
As Boothby put it, "Exploring the unique survival strategies employed by tardigrades under extreme stresses, including those experienced during spaceflight, can help us protect humans against these stressors. This is essential for ensuring the safety and success of deep space or long-term manned space missions."
The discovery of the radiation resistance mechanisms in tardigrades could lead to the development of advanced radiation shielding technology for astronauts during prolonged space travel. Further investigation into the genetic adaptations of tardigrades, such as the gene TRID1 and its role in DNA repair, could provide valuable insights for protecting human cells from radiation damage.