Discovery of Heat-Resistant Amoeba Challenges Limits of Complex Life

• NASA-supported scientists discovered Incendiamoeba cascadensis, a heat-loving amoeba, in California’s Lassen Volcanic National Park that thrives at temperatures previously thought impossible for complex eukaryotic life.
• The organism reproduces at 145 degrees Fahrenheit (63 degrees Celsius) and remains active while searching for food up to 147 degrees Fahrenheit (64 degrees Celsius).
• This discovery challenges the long-held assumption that organelle membranes in eukaryotes cannot remain stable above 144 degrees Fahrenheit (62 degrees Celsius).

Adaptation and Genomic Insights

• The research team sequenced the amoeba's genome, revealing specific genes that stabilize DNA and maintain protein folding at extreme heat.
• I. cascadensis utilizes proteins with high positive surface charges, a strategy also observed in thermophilic bacteria and archaea to ensure stability.
• Genetic data suggests similar thermophilic amoebas may exist globally, with potential matches identified in samples from New Zealand and Yellowstone National Park.

Implications for Astrobiology

• Studying such extremophiles helps scientists define the physiological and biochemical boundaries for life, guiding the search for habitable environments on other planets like Mars.
• While the finding expands the potential for complex life in extreme conditions, researchers emphasize that survival requires a broader ecosystem, including specific levels of acidity, oxygen, and nutrients.
• The study, published in the journal Cell, broadens the scientific understanding of how and where complex, multi-organelle cells can persist.