41 st SaasFee course from Planets to Life 39 April 2011 Lecture 2: - - PowerPoint PPT Presentation
41 st SaasFee course from Planets to Life 39 April 2011 Lecture 2: The top down approach to understanding the origin of life cont. Understanding the characterisFcs of the organisms close to the root of the tree Most are
Cells with membrane-bound nucleus and other organelles No No Yes DNA circular1 Yes Yes No Ribosome size 70S 70S 80S Membrane lipids Ether linked Ester linked Ester linked Cell walls No PDG2 PDG No Histone proteins Yes No Yes Operons in DNA Yes Yes No Ribosome structure distinct distinct Archaeal-like Antibiotic sensitivity No Yes No Photosynthesis No Yes Yes Growth at temperatures >80°C Yes Yes No
*There are many physiological characterisFcs that are found only in bacteria and
PDG but do have at least 7 different cell surface layers (protein, lipid, etc)
The blobfish (Psychrolutes marcidus) is found at depths greater than 5000 m off the coast
buoyant, the flesh of the blobfish is a gelaFnous mass with a density slightly less than water. This allows the fish to float above the sea floor without expending energy on
a disadvantage as it primarily swallows edible macer that floats by in front it (adult blobfish ~30 cm long). This crustacean invades a fishes mouth, devours its tongue, and takes the tongues place. It then acts like a tongue; the fish can use it to grip and swallow prey ‐ the parasite gets first dibs at the food. (From: Carl Zimmer, Parasite Rex, Simon & Schuster)
TarFgrades are between 0.05 and 1.2 mm in length, have feet with claws like bears and walk like bears. They are found everywhere including hot springs, in a 5m layer of solid ice, on the top of the Himalayas, stone walls etc but mostly live in moss. They could survive on Mars because:
Dry form “tun” Asphyi.c state ‐O2 coming back to life
“gummy bear”
What does this tree tell us about the evolu8on of organisms?
1. There are three domains of life 2. All extant life arose from a common ancestor 3. Bacteria and Archaea thought to be part of the same group of organisms (prokaryotes, Monera etc) are disFnctly different 7. The Eukarya evolved from the archaea 8. The deepest rooted organisms are thermophiles (hyperthermophiles)
diplomonads and ciliates)
~-50 - >1200°C Lowest Temperature -15°C Highest Temperature - 122°C Eukaryotes to 62°C ;metazoans to ~50°C
0 - 14 Bacteria, Archaea and fungi at pH 0 - 13
Distilled H2O to total dryness Highest salt - 35% NaCl (many microbes and animals can survive desiccation)
Generally less than 1 kGy Some microbes survive levels 10X higher than found naturally on Earth
Depends on environments and specific metals (>10mM) Bacteria and algae grow in 2-5mM Cd, Zn, Ni etc
<1 to ~1,100 atm (subseafloor habitas possibly to >6 km in the crust) High diversity of bacteria, invertebrates and fish in ocean trenches
Enzyme acFvity in water/organic solvent mixture (Bragger et al., 2000)
(Modified from Deming and Eiken, 2007)
Temperature range for microbial growth and survival: 1. Microbial growth at ‐15°C and up to at least 122°C 2. Enzyme acFvity at low temperature depends on liquid solvent 3. Salts and extracellular polysaccharides (EPS) can protect cells; some hyperthermophiles have >4M K at high temperatures 4. Bacterial spores and vegetaFve cells have been observed from million year ice cores 5. Anaerobes including methanogens (along with methane) in ice cores 6. Anaerobic methane oxidizing archaea associated with methane hydrates
(122°C)
Maximum growth T for eukaryotes (70°C) Maximum growth T for metazoans (~50°C) Viable microbes observed at 250°C
Highest Temperature Organism on Earth from Finn (Mothra) 2 m
3 days growth 1.03 m
Kashefi et al., Science 2003
A Pyrodic8um species has been described (Science 301:934, 2001) that can grow up to 121ºC, and a strain of Methanopyrus kandleri has been shown to grow up to 122ºC (PNAS 105:10949, 2008)
FISH staining of vent chimney TEM, P. fumarii cell
(Reinhard Rachel)
Red, Archaea; Green, Bacteria (Chris.an Jeanthon)
Red, Nanoarchaeum Green, Ignicoccus 0.4 µm
Photos by Reinhard Rachel
Heat-stable proteins; heat- shock proteins (chaperones)
Reverse DNA gyrase; introduces positive supercoiling into the chromosome, which raises the melting point; stabilizing proteins
Tetra-ether lipid monolayer membranes; covalent bonds adjoining membrane halves resist membrane peeling
Diverse anaerobic energy metabolisms; S0- and H2- based metabolisms
Size: up to 150 mm Distribu.on: East Pacific Rise from 21°N to 23°S Biology: Dwells inside organic tubes in acFve chimney walls. Temperature growth range 20‐50°C but can tolerate exposure to temperatures >100°C; Feeds on bacteria;
Photograph of a video taken from DSRV Alvin in hydrothermal vents at 21°N, East Pacific Rise, showing an Alvinella pompejana worm standing
Sketch to clarify the posiFon of the worm and the temperature probe
Scanning electron micrograph ‐ head size is 3 cm
Cary et al., Nature 391:545‐546 (1998)
Science 312:231 (2006)
Schema.c of the thermal gradient aquarium. Chamber consisted of : (A) aluminum reinforcement plate; (B) clear polycarbonate window; (C) PEEK ouwlow tubing; (D) holes drilled into the block to within 2.5 mm of the slot containing animals for inserFon of temperature probe; (E) )‐ring face seal; (F) slot to contain animals; (G)PEEK inflow tubing; and (H) an anodized aluminum block with a slot to contain animals.
DistribuFon of P. sulfincola and P. palmiformis worms in temperature‐gradient experiments. Worms were uniformly dispersed within the aquaria before establishing the temperature
distribuFons over Fme within a 20° to 61°C gradient; N = 5, 9 and 4 individuals, respecFvely. (D) Plot of P. palmformis distribuFons over Fme within a 20° to 55°C gradient; N = 8 individuals.
(Deming, 2009)
←Photos by Jim Staley→
Losest temperature for growth:
Psychromonas ingrahami Topt= +4°C, Tmin= –12°C, Tmax= +10°C
Marine sea ice
Middelboe et al., 2002 (seawater) Borriss et al., 2003 (sea ice) Wells and Deming, 2006 (both)
Colwellia psychrerythraea strain 34H
3 µm 3 µm 3 µm
(Borriss et al., 2003) (Wells and Deming, 2006)
Prevent ice-crystal formation and cell death Enable protein activity: enzymes must maintain significant catalytic activity at low temperature Maintain membrane function: the
significant levels of nutrient transport at low temperature
Live in a briny habitat, produce compatible solutes and/or exopolysaccharides (EPS) Make more flexible proteins (higher α-helix; lower β- sheet content) Make more polar and less hydrophobic proteins, with fewer weak bonds (ionic, hydrogen) Make lipids with greater content
and unsaturated fatty acids
The Antarc;c ice‐fish (Channichthyidae) are the only known vertebrates without
adaptaFon to life at temperatures that are less than 0°C (icefish size 25 cm long) (Wikipedia)
“I can see no limit to this power