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Explore the world of extremophiles in extreme environments and their biological adaptations. Discover the significance of extreme conditions on organisms and their practical implications.

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  1. Extremophiles 101Mark E. Nielsen, Ph.D.Science Education Fellow Educational Resources GroupHoward Hughes Medical Institute nielsenm@hhmi.org www.biointeractive.com All text is Times New Roman Presentation Title:24/25 24 before; Bold, White, All Caps Subtitle: 22/25, 24before, White. Italic Name: 24/25, 24 before, bold, White Title: 14/25, 24 before , White Date: 14/25, 24 before , White Text Box Position, from top left: hz: -0.74” vt: 2.93”

  2. Outline for today’s talk • Introduction and few definitions • Tour of extreme environments • biological ramifications • coping mechanisms • interesting highlights • Practical implications/considerations

  3. What is normal and what is extreme? For any particular property (T, pH, salinity) extreme values are values far from the typical range for human life Physical extremes: - Temperature - Pressure - Radiation Geochemical extremes: - pH (acidity levels)‏ - Salinity - Desiccation - Oxygen species - Redox potential

  4. What is normal and what is extreme? For any particular property (T, pH, salinity) extreme values are values far from the typical range for human life Physical extremes: - Temperature - Pressure - Radiation Geochemical extremes: - pH (acidity levels)‏ - Salinity - Desiccation - Oxygen species - Redox potential

  5. Why cover extremophiles in an astrobiology workshop? Mars Europa

  6. DiversityWho are the extremophiles?

  7. Environmental Extremes – What do they mean to the organisms? Temperature protein denaturation, reduced solubility of gases, Increases fluidity of membranes, chlorophyll degrades at 75 °C ice formation (physical stress), lack of liquid water (chemical stress)

  8. Cell membranes Membrane fluidity is related to composition of fatty acids

  9. Other high temperature adaptations Histones – proteins that bind to DNA Different chemical bonds

  10. Environmental Extremes – What do they mean to the organisms?

  11. Environmental Extremes – What do they mean to the organisms? Radiation = Energy in transit as particles (e.g., electrons, neutrons, protons, alpha particles) or waves (gamma rays, x-rays, UV) Rarely occur but high UV exposure can occur DNA damage directly or indirectly from ROS Deinococcus radiodurans "A lethal level of radiation for humans is about 700 rads. The bacterium Deinococcus radiodurans can withstand 1.5 million... There’s never been anything like this level of natural radioactivity on earth in its 4.6 billion year history, so how can we explain the evolution of such a capability?"

  12. Reactive Oxygen Species Oxygen is very corrosive to organic chemical bonds. Mechanisms evolved very early to deal with this • Early Earth may have had H2O2 rain • Organisms evolved anti-oxidants to deal with this • super oxide dismutase/reductase • catalase • peroxidase

  13. Environmental Extremes – What do they mean to the organisms? Pressure: Boiling pt. of water increases Volume changes Gravity – changes in biomass production rates, changes in membrane permeability

  14. Environmental Extremes Desiccation: Water is an unusual fluid that makes it unique and critical for life. Issues: irreversible phase changes to lipids, proteins, and nucleic acids through denaturation and chemical reactions (Maillard reactions)

  15. Environmental Extremes pH Lots of H+ can denature proteins (ceviche) Acidophiles thrive at low pH Alkaliphiles thrive at high pH (an equally challenging environment) protons are scarce so energy tough to come by Ferroplasma acidarmanus

  16. Environmental Extremes pH Lots of H+ can denature proteins (ceviche) Acidophiles thrive at low pH Alkaliphiles thrive at high pH (an equally challenging environment) protons are scarce so energy tough to come by

  17. Environmental Extremes Salinity Halophiles – organisms with adaptations to grow in high salt conditions (up to saturation!). Adaptation: Increasing osmotica intracellularly (e.g., K+, betaine, glutamate, sucrose) Dunaliella salina Halobacterium (actually Archaea)

  18. Summary of extremophiles and their environments

  19. Biotechnological relevance

  20. Biotechnological relevance Thermus aquaticus – DNA polymerase

  21. Biofuels – A challenge and an opportunity

  22. Biofuels – A challenge and an opportunity Bioelectrosynthesis Microbes can accept electrons from solid surfaces to fix carbon

  23. Biofuels – A challenge and an opportunity

  24. Bringing it back to astrobiology

  25. Lake Vostoc: A model for Life on Europa?

  26. A good Source Nature, Vol. 409, February 2001

  27. Questions? temperatures as low as -200 °C (-328 °F) and as high as 151 °C (304 °F); freezing and/or thawing processes; changes in salinity; lack of oxygen; lack of water; levels of X-ray radiation 1000x the lethal human dose; some noxious chemicals; boiling alcohol; low pressure of a vacuum; high pressure (up to 6x the pressure of the deepest part of the ocean)

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