Kiwa hirsuta ye$ crab? Size: Carapace length, 51.5 mm, total length - - PowerPoint PPT Presentation

Kiwa hirsuta “ye$ crab?

Size: Carapace length, 51.5 mm, total length 88.4 mm Distribu,on: Pacific Antarc$c Rise – German Flats, 38S Biology: Occurs at densi$es of one or two individuals per 10 meters, more or less regularly spaced on the zone of pillow basalts surrounding ac$ve hydrothermal vents, and at the base of chimneys among vent mussles (Bathymodiolus sp) other crabs and ophidiid

• fish. Omnivorous.

Ye, Crab

41stSaas‐Fee course from Planets to Life 3‐9 April 2011

Lecture 6 ‐ Origin of Life and its Early Evolu$on on

Earth

• Mineral needs – con$nued
• Condi$ons on Earth that provide the essen$als

for life to start and evolve

– Tectonics, chemical energy sources, trace elements, minerals

• Metabolism and geochemistry

– Early metabolism – The Earth’s “enrichment period”

• The first microbial community – a possible model

system

How to get high concentra$ons of useful

• rganic compounds?
• Specific synthesis – requires catalysts (minerals)
• Very limited data at the present $me, but

preliminary data looks very promising

Keep in mind that the cataly$c reac$ons carried out by proteins in present‐day organisms was very likely carried out by minerals before the gene$c code and ribosomes were fully developed

Some early ideas about minerals and the

• rigin of life

Cairns‐Smith Clay Model for the origin of life Clay crystals

Crystal growth and “muta$on”

Condense organic compounds (clays as templates and reac$ve surfaces)“organic takeover”

Macromolecules Cells Crystal growth occurs by addi$on of units

• f the kink edge of a con$nuous ramp

spiraling around the central core Informa$on stored in crystals as a group of crystal “defects” that can be replicated through cleavage and crystal growth

Examples of possible reac,ons involving pyrite based on pyrite having a ca,onic surface in which a variety of anionic reac,ons are possible. The example in (A) is the adsorp,on of glyceraldehyde‐3‐phoshate to the surface followed by polymeriza,on. (B) Par,cipa,on of pyrite in a reac,on that can drive and otherwise energe,cally unfavorable reac,on. For example, the reduc,on of CO2 by H2 has a posi,ve Gibbs free energy reac,on. However, if CO2 reduc,on is linked to the pyrite reac,on the synthesis of formic acid is energe,cally favorable

Organic reac,on on pyrite surfaces under hydrothermal condi,ons (Wächterhäuser, 1988, 1998)

Pyrite

Wächterhäuser Model 1980’s Pyrite Organic synthesis and condensa$on “surface metabolites” Informa$on Macromolecules CELLS Russell Model 1990’s FeS membranes (bubbles formed from a mix of acidic seawater and alkaline hydrothermal fluid) Organic synthesis (ΔEh across membrane) Metabolic pathway Condensa$on reac$ons Informa$on macromolecules CELLS

Models for the origin of life in vent environments

Some ongoing work with minerals

References of interest:

• 1. Hazen, R.M. et al., 2008. Mineral evolu$on.

American Mineralogist 93:1693‐1720

• 2. Cody, G. J. 2004. Transi$on metal sulfides and

the origin of metabolism. Ann. Rev. Earth

• Planet. Sci. 32:569‐599

Mineral surfaces that may be involved in the origin of life

Mineral Surface Properties Lava minerals Si, O, Fe Major mineral surface on early Earth Apatite Ca, PO4

2-

Primary phosphate mineral Clays Si, Al, O Can organize organics into films and catalyze polymerization reactions Pyrite FeS2 Source of reducing power Calcite CaCO3 Chiral surfaces; concentrate

• rganics such nucleotides from

models Quartz SiO2 Chiral surfaces Ultramafic minerals Fe, Mg Generate hydrogen and organic compounds from CO2 Borate minerals B Catalyze the synthesis of ribose Elemental composi$on

Mineral Needs

• Catalyze metabolic networks that involve

the reduc$on of CO2 to organic compounds.

• There is a need to iden$fy the cataly$c

ability of other minerals under different T/ pH condi$ons (minerals that mimic known enzyme groups: oxidoreductases, transferases, hydrolases, lyases, isomerases and ligases)

We can accomplish this by looking at minerals that contain the metals that are present in different minerals and examine their cataly,c ac,vity under the environmental condi,ons that they can form and remain stable

Are there realis$c early‐Earth segngs that support the “metabolism first”, or the “replicator first” and the encapsula$on models? What about the source sites of cataly$c minerals?

• The answer is there is much we

don’t know

• Earth‐like planets (acBve tectonism) will support life that uses

both chemical and light energy: the “Unity of Metabolism.”

• Prior to the appearance of heterotrophic eukaryotes

(single celled pro8sts), Earth’s microbial ecosystems would have been characterized by extremely high densi$es of specific metabolic groups of microbes: “The Enrichment Period” (the red, purple or green planet).

• The enrichment periods have the poten$al to affect the

chemistry of the atmosphere.

Condi$ons on Earth that provide the essen$als for life to start and evolve – Some hypotheses

Why is tectonism important for life?

• Water present
• Generate new crust and con$nents
• Produce hydrothermal systems

– Source of carbon, chemical energy and elements required for life (magma degassing, water/rock reac$ons and mineral catalysis) – Possible segng for the earliest microbial ecosystems – A possible “required” segng for the origin of life or steps leading to life

The “Unity of Metabolism” predicts that organisms (even with different

biochemistries than Earth organisms) on

any tectonically ac$ve planet (water) will use the same chemical energy sources and electron acceptors and donors as Earth organisms

Vola$les from magma‐hosted and perido$te‐hosted vents ‐ could they be detected in the atmosphere?

• Vola$les from Magma‐hosted vents: 3He, H2, CH4,

CO2, H2S, CO

• Vola$les from perido$te‐hosted vents: 3He, H2,

CH4, C1‐C5 hydrocarbons

• Modeling the atmosphere of a tectonically

ac,ve planet without life and with ecosystems at various stages in Earth’s history

Different microbial ecosystems/different atmospheres (chemical composi$on)

• Earth without oxygen and eukaryotes

(the absence of animal predators)

• The “Enrichment Period” of Earth history
• A pale dot of different hues

5.0 4.0 3.0 2.0 1.0 0.0 Billions of years ago on Earth

Solar system forma$on Late heavy bombardment

E a r l y f r e e z i n g /

• x

y g e n a $

• n

e v e n t s L a t e f r e e z i n g /

• x

y g e n a $

• n

e p i s

• d

e s

Billions of years on Mars

Noachian Hesperian Amazonian atmospheric loss

5.0 4.0 3.0 2.0 1.0 0.0

microbes Archaean Proterozoic Phanerozoic

pO2 <0.002 bar pO2 >0.03 bar pO2 >0.2 bar ferrous oceans sulfidic ocean oxic ocean cyanobacteria algae, pro$sts complex (2.7 Ga) animals & plants

Archaean

P O2 <0.002 bar Ferrous ocean Microbes Anoxygenic Photosynthesis, Cyanobacteria (2.7 Ga)

4 3 2 1 0 1033 1031 1029 1027 1025 1023 1021

K/T Ty

3000 30 0.3 0.003

Time (Ga) Water evaporated (m) Impact energy (J)

• rigin of life

The largest bolide impacts on the Earth and the Moon. Light gray filled boxes are lunar, black filled boxes terrestrial. Red line is inferred earth impact history. Dashed blue line is depth of ocean vaporized by impact. K/T refers to the Cretaceous/Tertiary impact and Ty refers to the lunar crater Tycho (From Sleep et al., 1989)

Life may have started during the heavy bombardment period

• heavy bombardment, while rendering the
• cean water column and any landmass that

may have existed uninhabitable, would not have removed all water from the subsurface and thus would not have sterilized the Earth, but would have resulted in widespread impact‐volcanism (Abramov and Mojzsis, 2009).

Billion years from human

Origin of Earth (4.5 Gya) Cyanobacteria (the rise of O2) Origin of life?

Thermophilic methanogens, S reducers (thermophilic N-fixation) 4 3 2 1 Anoxygenic photosynthetic bacteria?(anaerobic)

Accumulation of O2 Single celled eukaryotes

(beginning of prey/predator associations?)

Algal kingdoms Shelly invertebrates Vascular plants Mammals Humans Time of transition from anaerobic microbial ecosystems to aerobic microbial/eukaryotic ecosystems

Life may have started during the heavy bombardment period

• heavy bombardment, while rendering the
• cean water column and any landmass that

may have existed uninhabitable, would not have removed all water from the subsurface and thus would not have sterilized the Earth, but would have resulted in widespread impact‐volcanism (Abramov and Mojzsis, 2009).

Earth life requires the elements, vola$les and minerals produced as a result of tectonics and hydrothermal ac$vity

Electron donors, metabolism and vola,le metabolites on an anoxic Earth

(modified from Canfield et al 2006)

Electron donors Environmental settings Metabolism Metabolites in the atmosphere

H2 Submarine hydrothermal vents; subaerial volcanoes Methanogenesis, anoxygenic photosynthesis, SO4

2-, S°, FeIII

reduction, acetogenesis, denitrification CH4, H2S, N2O, N2, CO2 depletion? H2S Submarine hydrothermal vents; subaerial volcanoes anoxygenic photosynthesis NO3

• reduction

N2, decreasing H2S and H2, CO2 depletion? S° Submarine hydrothermal vents; subaerial volcanoes anoxygenic photosynthesis, NO3

• reduction, S disproportionation

N2, CO2 depletion? Fe(II) Submarine hydrothermal vents; subaerial volcanoes anoxygenic photosynthesis, NO3

• reduction

CO2 depletion? N2 CH4 Hydrothermal vents Anaerobic CH4 oxidation CO2 NH4

+

Hydrothermal vents Anammox N2, CO2 depletion? CH2O Hydrothermal vents heterotrophy CO2, H2

Timeline for Archean photosynthesis with proposed reductants (from Olson 2006)

Reductant Ga Marker

H2O 2.3 2.4 O2 level begins to rise H2O 2.5 Hamersley BIF H2O 2.6 Nauga cyanobacteria H2O 2.7 2.8; 2.9 Pilbara methylhopanes Tumbiana stromatolites Fe(OH)+ 3.0 3.1 Protocyanobacteria and Proteobacteria emerge? H2S 3.2 3.3 Swaziland barites H2 3.4 Buck Reef microbial mats (Tice and Lowe, 2006; Sleep 2010) H2S 3.5 3.6; 3.7 Warrawoona evaporites H2 3.8 Isua carbon isotope fractionation

Phototrophic Fe(II)‐oxidizing bacteria (Thodobacter ferrooxidans, Chrorobium ferrooxidans and Thiodictyon sp.) 4Fe2

+ + CO2 + 11H2O + hv → [CH2O] +

4Fe(OH)3 + 8H+ Purple sulfur bacteria (Chlorobiaceae, Chroma8aceae) 2HCO3

‐ + H2S → 2CH2O

+ SO4

2‐

Mul$ple groups of Bacteria and Archaea use H2 as energy source: methanogenesis, Phototrophic Bacteria; S reducers

Anoxygenic photosynthe$c bacteria

PNAS 102:9306‐9310, 2005 Morphology and ultrastructure

• f GSB1 cells. Bar, 300 nm

Chlorosomes

A Green‐sulfur photosynthe$c bacteria was isolated from a submarine hydrothermal vent smoker where the only source of light is geothermal radia$on that includes wavelengths absorbed by photosynthe$c pigments. This organisms is an

• bligate anaerobe and reduces CO2 coupled with oxida$on of

sulfur compounds

Photosynthe$c bacteria 2HCO3

‐ + H2S → 2CH2O + SO4 2‐

The Winogradsky Planet

(A model of the early Earth?)

Bacterial SO4

2-

reducers and methanogens An‐oxygenic photosynthesis (purple sulfur and green sulfur bacteria dominate)

Photomicrographs of different anoxygenic phototrophic bacteria from marine microbial mats. Sulfur globules seen in C

Planets of a different color

• Plants other than green (Kiang 2007) last 250

million years on Earth

• The anaerobic Earth including “The Enrichment”

period (no animal predators)

– Anoxygenic photosynthesis – Oxygenic photosynthesis? – Methanogenesis and S reucBon world – Halophile world (bacterial – Rhodopsin and carro$noids, etc) – Bacterial proteorhodpsin world – Luminescent world – Electric sparking world (microbial bapery world)

Salt flat in Australia

Satellite observa$on of a“glowing” area ~15,400 km2 of the Northwestern Indian Ocean believed to be the result of a massive bloom of luminescent bacteria (Miller et al PNAS 2005)

Electron donors, metabolism and vola,le metabolites on an anoxic Earth

(modified from Canfield et al 2006)

Electron donors Environmental settings Metabolism Metabolites in the atmosphere

H2

Submarine hydrothermal vents; subaerial volcanoes Methanogenesis, anoxygenic photosynthesis, SO4

2-, S°, FeIII

reduction, acetogenesis, denitrification CH4, H2S, N2O, N2, CO2 depletion? Nealson et al., 2005

The Hydrogen World

The segngs and metabolism of the earliest microbial communi$es

• All evidence points to hydrogen as the earliest

source of chemical energy (both non‐ photosynthe$c and photosynthe$c organisms)

• Hydrothermal vent environments would have

provided the hydrogen, other vola$les (CO2, sulfur compounds, nitrogen, etc) and key elements to support life

• Evolu$onary phylogeny of extant organisms

support the hypothesis of hydrogen u$lizing, high temperature microbes as ancient groups

From Nisbet and Sleep, Nature 2001

Life styles of Hydrogen u,lizing anaerobic microbes

• Commonly form complex macrocolonies and

biofilms

• Most use CO2 as a source of carbon with CO2, or S

° or Fe(III) as the electron acceptors

• Grow in most of the extreme anaerobic

environments

• Those from extreme environments usually grow as

biofilms on minerals (pyrite, calcite, basal$c glass,

• xyhydroxy iron minerals, etc)
• The first photosynthe$c bacteria used H2 as the

electron donor (~3.5 Ga)

What are the likely metabolic pathways of ancient hydrogen u$lizing microorganisms?

Geological sites relevant to the origin of life (Modified from Deamer, 2007)

(modified from Deamer 2007)(

SITE PROPERTIES

Inter-tidal zones, tide-pools, sand Fluctuating environment can concentrate organic solutes Fresh water ponds, lakes Moderate T°C ranges. Low mineral content can be conducive to self-assembly processes. Impacted by lightning, bolides etc. Ice fields Organics can be concentrated in eutectics within ice. Low T°C preserves organic compounds Subterranean geothermal regions T°C range from moderate (40-60°C) to boiling. Reducing power available Magma-hosted Hydrothermal vents T°C range from 2°C (present day) to >400°C with everything in between . Multiple gradients in physical and chemical conditions. Reducing power and catalytic minerals available Peridotite-hosted Hydrothemal vents T°C to >90°C, pH up to 11; high concentrations of CH4, formate, acetate and low MW hydrocarbons; porous calcite for concentration of organic compounds Atmosphere, clouds Water droplets as “cell-like” enclosures for synthesis of complex

• rganic compounds using UV light

Radioactive Beaches (Adam, Astrobiology 2007) The possible role of Actinides (elements with atomic numbers between 89-103) in the abiotic synthesis of organic compounds, polmerization reactions; P release from minerals

Summarizing the case for a subseafloor sedng for

the origin of life and early microbial ecosystems

• Extensive bolide impacts before 3.8 Ga including ocean

evapora$ng impacts (Maher & Stevenson, 1988; Sleep et al., 1989)

• Liple con$nental mass before 3.8 GA (Lowe, 1994)
• Extensive hydrothermal ac$vity in the early Archaean

with ridge lengths >5X present (Bickle, 1978; Nisbet and Sleep, 2001)

• Lots of hydrogen and CO2
• Abundant and diverse cataly$c minerals from geophysical

processes

• Extensive temperature, pH and chemical gradients
• Source of Fe/S, C compounds, C‐S compounds, P with

serpen$ne (alkaline hydrothermal systems) thio‐esters

• Sources of thio‐esters, ammonia and phosphate not well

understood

Hydrogen‐based ancient metabolisms

• CO2 ‐ reducing pathways
• Occur under anaerobic condi$ons
• Reac$ons catalyzed by minerals
• Produce organic precursors for mineral

catalyzed synthesis of amino acids, nucleo$des, sugars etc

Autotrophic CO2 fixa$on pathways in Bacteria and Archaea

Metabolic Pathways Organism (examples) Domain Comments Ref. Calvin-Bensen Cycle

Plants, cyanobacteria, Thiobacillus spp Bacteria Aerobic and denitrifying Karl, 1995 and others

Reductive acetyl-CoA pathway

Planctomyces spp Methanocaldococcus jannaschii; Lost City Methanosarcinales Bacteria Archaea Strictly anaerobic

See Thauer 2007; Hügler et al., 2003 for references

Reductive Citric Acid Cycle

ε-proteobacteria; Aquifex/ Hydrogenobacter Pyrobaculum spp Thermoproteus spp Bacteria Archaea Anaerobic and microaerophilic Hügler et al., 2003; 2005

3-hydroxypropionate/ Malyl-CoA cycle

Chloroflexus spp Bacteria Microaerophilic Strauss & Fuchs, 1993

3-hydroxypropionate/ 4-hydroxybutyrate cycle

Nitrosopumilus spp Archaeoglobus Sulfolobus Bacteria Archaea Microaerophilic Berg et al., 2007

Unknown pathways

Ignicoccus spp Pyrodictium spp Archaea Strictly anaerobic

Hügler et al., 2003; Jahn et al., 2007

Metabolism summary

• There are hydrogen u$lizing microbes that use

most of the metabolic pathways

• Obligate hydrogen u$lizing microorganisms

(include methanogens, acetogens, sulfur u$lizers and photosynthe$c bacteria) are anaerobic

• All of the CO2 pathways are found in

microorganisms from hydrothermal vents

A point to make…..and hypotheses

Hypothesis about the segngs for the

• rigin of life
• A dynamic ocean/subsurface circula$on system was

necessary to transport various organic compounds synthesized under a specific set of condi$ons to other environments for further reac$ons that would result in a greater diversity of organic compounds, including

• rganic‐nitrogen, sulfur and phosphorus compounds,

macromolecules and “proteometabolic” networks.

• A narrow subset of the condi$ons spawned and

maintained early life forms (decouple the environmental condi$ons that led to life to the narrow condi$ons of the first habitat for life)

Overview of sites present on the early Earth that may have contributed to the origin of life. Blue arrows indicate water flor between different reservoirs

Geological sites relevant to the origin of life (Modified from Deamer, 2007)

(modified from Deamer 2007)(

SITE PROPERTIES

Inter-tidal zones, tide-pools, sand Fluctuating environment can concentrate organic solutes Fresh water ponds, lakes Moderate T°C ranges. Low mineral content can be conducive to self-assembly processes. Impacted by lightning, bolides etc. Ice fields Organics can be concentrated in eutectics within ice. Low T°C preserves organic compounds Subterranean geothermal regions T°C range from moderate (40-60°C) to boiling. Reducing power available Magma-hosted Hydrothermal vents T°C range from 2°C (present day) to >400°C with everything in between . Multiple gradients in physical and chemical

• conditions. Reducing power and catalytic minerals available

Peridotite-hosted Hydrothemal vents T°C to >90°C, pH up to 11; high concentrations of CH4, formate, acetate and low MW hydrocarbons; porous calcite for concentration of organic compounds Atmosphere, clouds Water droplets as “cell-like” enclosures for synthesis of complex

• rganic compounds using UV light

Radioactive Beaches (Adam, Astrobiology 2007) The possible role of Actinides (elements with atomic numbers between 89-103) in the abiotic synthesis of organic compounds, polmerization reactions; P release from minerals

The segngs and metabolism of the earliest microbial communi$es

• All evidence points to hydrogen as the earliest

source of chemical energy (both non‐ photosynthe$c and photosynthe$c organisms)

• Hydrothermal vent environments would have

provided the hydrogen, other vola$les (CO2, sulfur compounds, Nitrogen, etc) and key elements to support life

• Evolu$onary phylogeny of extant organisms

support the hypothesis of hydrogen u$lizing, high temperature microbes as ancient groups

There is a higher probability for life and a separate origin of life on a tectonically ac$ve planet with water and volcanism.

Two Kinds of Hydrothermal Vent Environments and other related environments

1. Magma‐hosted vent environment

a. Extensive surface and subsurface environments b. Vola$les and elements from water/rock interac$ons and magma release

2. Periodite‐hosted vent environments

1. Off‐axis in slow spreading areas 2. Very different chemistry from magma‐hosted systems 3. Mud volcanoes Note: there are also cold seeps, methane hydrates, whale falls, etc that have micro‐ and macrofauna that are similar to those at hydrothermal vents

Extreme physical and chemical condi$ons at different vent systems

Magma hosted hydrothermal systems ‐ Most elements required for life

‐ Carbon sources, cataly$c minerals ‐ Temp to >400°C ‐ pH <3; sulfide chimneys

Perido8te hosted hydrothermal systems ‐ High concentra$ons of H2, CH4 and

• ther hydrocarbons and organic acids

‐ Temp to >90°C ‐ pH to ~11 ‐ Carbonate chimneys

Kelley 2001

Closing comments

• Geological $me scales and environmental segngs are

probably necessary for different “stages” in the origin of life

• There is a need for essen$al elements and inorganic

compounds (sources and concentra$ons)

• Need to beper understand sources (source reac$ons) of

precursor organic compounds

• Concentra$on and condensa$on of organic compounds
• The origin of life trinity: RNA, metabolism and pep$des and

are their development interdependent?

• Ribozymes to RNA genes to transla$on to DNA to evolu$on,

etc (Why didn’t this progression stop with some minimal RNA that just replicates

• Don’t understand pathways leading to biochemical and

cellular complexity and the origin of eukaryotes

Geological sites relevant to the origin of life (Modified from Deamer, 2007)

(modified from Deamer 2007)(

SITE PROPERTIES

Inter-tidal zones, tide-pools, sand Fluctuating environment can concentrate organic solutes Fresh water ponds, lakes Moderate T°C ranges. Low mineral content can be conducive to self-assembly processes. Impacted by lightning, bolides etc. Ice fields Organics can be concentrated in eutectics within ice. Low T°C preserves organic compounds Subterranean geothermal regions T°C range from moderate (40-60°C) to boiling. Reducing power available Magma-hosted Hydrothermal vents T°C range from 2°C (present day) to >400°C with everything in between . Multiple gradients in physical and chemical

• conditions. Reducing power and catalytic minerals available

Peridotite-hosted Hydrothemal vents T°C to >90°C, pH up to 11; high concentrations of CH4, formate, acetate and low MW hydrocarbons; porous calcite for concentration of organic compounds Atmosphere, clouds Water droplets as “cell-like” enclosures for synthesis of complex

• rganic compounds using UV light

Radioactive Beaches (Adam, Astrobiology 2007) The possible role of Actinides (elements with atomic numbers between 89-103) in the abiotic synthesis of organic compounds, polmerization reactions; P release from minerals