NASA astrobiologist went out to the hyper saline Lake Mono California (eastern edge of Yosemite National Park) looking for extremeophiles, microorganisms that thrive in places that would be lethal to most other organisms. This enables the astrobiologists to better understand how life can arise elsewhere in our solar system and beyond. Well, they found one, GFAJ-1 strain of Gammaproteobacteria uses toxic arsenic as a key building block of its DNA, causing astrobiologists to re-think the possibilities for life on and off our planet:
NASA-supported researchers have discovered the first known microorganism on Earth able to thrive and reproduce using the toxic chemical arsenic. The microorganism, which lives in California’s Mono Lake, substitutes arsenic for phosphorus in the backbone of its DNA and other cellular components.
A microscopic image of GFAJ-1 grown on arsenic. [larger image]“The definition of life has just expanded,” said Ed Weiler, NASA’s associate administrator for the Science Mission Directorate at the agency’s Headquarters in Washington. “As we pursue our efforts to seek signs of life in the solar system, we have to think more broadly, more diversely and consider life as we do not know it.”
This finding of an alternative biochemistry makeup will alter biology textbooks and expand the scope of the search for life beyond Earth.
Carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur are the six basic building blocks of all known forms of life on Earth. Phosphorus is part of the chemical backbone of DNA and RNA, the structures that carry genetic instructions for life, and is considered an essential element for all living cells.
Phosphorus is a central component of the energy-carrying molecule in all cells (adenosine triphosphate) and also the phospholipids that form all cell membranes. Arsenic, which is chemically similar to phosphorus, is poisonous for most life on Earth. Arsenic disrupts metabolic pathways because chemically it behaves similarly to phosphate.
Here are some photo’s of Mono Lake
Arsenic as a replacement for phosphorous in ATP, DNA, and phospholipids…amazing how life will adapt…what fits, survives.
