Transcript PROGRAM_&_PDfs_files - Instituto de Astrofísica

Exoplanetary
environments to harbour
extremophile life as we
don´t know it
Claudia LAGE
[email protected]
Instituto de Biofísica Carlos Chagas Filho
Universidade Federal do Rio de Janeiro/Brazil
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Outline
General surviving strategies to extreme
environments found in micro-organisms
Deinococcus, a radiation survivor
Searching for new extremophiles on Earth
Concerns on the Panspermia connection with
life as we don´t know it
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The quest for perfect DNA duplication involves a protein complex
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Hyperthermophilic organisms mixed functions of an entire protein complex
in a single protein
DNA primase
DNA helicase
DNA polymerase
Rossi et al., J Bacteriol, 2003
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Stronger surface charges cause hyperthermophilic proteins to stabilise
complexes under higher temperatures
Archaeal PCNA
Yeast PCNA
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Low-temperature dependence for cold-loving species growth
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Low-temperature adaption of cold-loving species membranes
Membrane lipid structure in mesophilic organisms
Membrane lipid structure in cold-loving micro-organisms
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Solvent (concentration)
log
Pow
Staphylococcus sp.
strain ZZ1
B. cereus
strain ZZ2
B. cereus
strain ZZ3
B. cereus
strain ZZ4
Hexane 100 mM [1.3%
(v/v)]
3.5
+++
+++
+++
+++
Cyclohexane 100 mM
[1% (v/v)]
3.2
+++
+++
+++
+++
p-Xylene 100 mM [1.2%
(v/v)]
3.0
+++
-
±
-
Toluene 50 mM [0.53%
(v/v)]
2.5
+++
+++
+++
+++
Toluene 100 mM [1%
(v/v)]
2.5
+++
±
+++
+++
1-Heptanol 100 mM
[1.4% (v/v)]
2.4
-
-
-
-
Dimethylphthalate
100 mM [2% (v/v)]
2.3
+++
-
+++
+++
Fluorobenzene 100 mM
[1% (v/v)]
2.2
+++
+++
+++
+++
Benzene 100 mM [1%
(v/v)]
2.0
+++
+++
+++
+++
Phenol 20 mM [0.18%
(v/v)]
1.5
+++
-
+++
+++
+++ growth overnight (16 h); ± minimal growth ASTROBIO Isolation
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characterization
of novel organic solvent-tolerant
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overnight; - no growth
bacteria, Zahir et al. Extremophiles 2005 Oct
Oceans
of
organic
compounds are present
in exoplanets and their
moons... e.g. Titan
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They have been here since the beginning
(chlorophyll-containing fossilisations in ~2,5Gyr
Australian estromatolites)
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ORIGINS OF LIFE ON EARTH
HOW CLOSE ARE WE TO MICRO-ORGANISMS?
STRESS RESPONSES ARE ALWAYS UP-TO-DATE!
www.ncbi.nlm.nih.gov/BLAST/
Homo sapiens
Silicibacter sp.
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What´s up there in outer space?
No heat
No gases
No water
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Panspermia
Transport
Density: 1 to 106 molecules.cm-3
Pressure > 10-17 atm
Radiation UV: 122.3 J.m-2.s-1
Temperature = 0 to hundreds K
Ejection
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Reentry
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Bacterial SPORES were shown to survive a 6-yr exposure to low Earth
orbit radiation
Horneck et al., Adv Space Res, 1994
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Observation may be confusing in the search for life…
Avenca
Mineral deposit on rock
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???
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About Deinococcus...
•
•
The radiation constraint…
4Gy gamma rays to humans =

•
15.000Gy gamma rays to radiodurans
•

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Deinococcus radiodurans
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SIMULATION
EXPERIMENT
IN
THE SINCHROTRON
LIGHT
NATIONAL
LABORATORY,
Campinas, Brazil
CELL POWDER
+
HIGH VACUUM
+
WHITE BEAM VUV
SOLAR RADIATION
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http://microbialgenomics.energy.gov/primer/featured_bugs.shtml
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Superfície microscópica
da fita de carbono
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MAUA 17 OUT 2009
CONCORDIA MICROMETEORITES
CARBON TAPE
100µm
Morphologic comparison between surfaces of Concordia 2002 micrometeorite (Antartica)
and that of the carbon tape on which bacterial powder was layered for irradiation (with
permission of M. Maurette)..
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Viabilidade
de Deinococcus radiodurans
radiodurans sobunder
condições
de
Viability
of Deinococcus
shielding
Panspermia
conditions
1.00E+01
Sobrevivência (N/NO)
1.00E+00
1.00E-01
Fragmentos de Meteoritos
Solos do Deserto do Atacama - Sítio Maria
Helena
1.00E-02
1.00E-03
1.00E-04
0
2
4
6
8
10
12
14
16
18
20
Doses (KJ)
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Multiple secondary radiation effects enhance
energy absorption by a large rock fragment
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Micro-sized particles have lower probability to
interact with radiation
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ATACAMA has life and you don´t see it
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45
40
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Alfa
Beta
Gamma
Cf
SRB
Arch
Eub
%
30
25
20
15
10
5
0
Stromatolite
Mats
Mats
Water table
Well
Phylogenetic group
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Sítio Maria Elena – Atacama - Chile
Marte
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WATER ICE UPON MARS LANDING OF PHOENIX!!!
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Searching for novel radiation resistant
micro-organisms !!!
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UV (254nm) survival of bacterial isolates from
Antarctic samples
Growth curves after 300J.m -2 UV
(single dose)
N/No
Growth curves of control cultures
1000
N/N0
1000
100
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10
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136-D
1
100
57
10
46
1
136-D
0,1
0,1
0,01
0,01
0
3
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6
0
Days
3
6
Days after UV
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KOISTRA et al., 1958:
The behaviour of microorganisms
environmental conditions.
under
simulated
Martian
- low pressure chamber (0.06 mbar);
- soil samples from distinct geographic regions (in natura specific
microflora);
- initial counts of colonies and after 1, 2 and 3 months under
martian conditions;
- environmental “simulation” = cycles of 9h at 25oC, then 15h at 22oC.
Results:
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Surface temperature estimates for
some known exoplanets
• The surface temperature estimation depends not only on the
stellar temperature but also e.g. on the planet's albedo and
atmospheric chemical composition which will define the
extent of the greenhouse effect and on how the heat is
distributed around the planet
• The present sample of known exoplanets is strongly biased:
e.g., long period planets are much more difficult to detect.
• Surface temperatures of the known exoplanets are on the
average higher than for planets in the Habitable Zone (HZ)
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– Surface temperatures of a number of Neptune-like
planets have been estimated (e.g., Rivera et al. 2005,
Bonfils et al. 2005; Bonfils et al. 2007; Demory et al.
2007)
– They are supposedly mainly composed of icy/rocky
material, being formed without or having lost the
extended gaseous atmosphere
– Some of them have orbital periods between 2 and 6
days and surface temperature ranges from 400 to 700 K
– Even in these particular cases, extremophiles existing on
Earth (hyperthermophiles) could live even in the coldest
of them
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MOST FAVOURABLE KNOWN CASE:
Gliese 581c (Udry et al. 2007)
A 5 MEarth planet in the HZ of a MV (red) star
For Earth-like or Venus-like albedos, the surface
temperature of Gliese 581c is estimated to range between
270 and 313 K, respectively.
Many extremophiles could live under these conditions!
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INTERESTING POSSIBILITY: moons of planets in the
HZ
Jupiter-like planets in the HZ:
Examples:
HD10697 (G5V ; 6.35 MJ, 1072 d orbit) TS  264 K
HD37124 (G4V ; 1.04 MJ, 155.7 d orbit) TS  327 K
HD134987 (G5V ; 1.58 MJ, 260 d orbit) TS  315 K
HD177830 (K2IV ; 1.22 MJ, 392 d orbit) TS  362 K
HD222582 (G3V ; ?? MJ, 576 d orbit) TS  234 K
Extremophiles could live “confortably” under these temperatures
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SUMMARY OF KEY POINTS
The flux of solid material (large dust meteoroids) arriving on Earth from
nearby stars was estimated in detail by Murray et al. (2004) from radar
detections: ~ 10 yr-1·km-2; estimates on the amount of micro-sized
material coming to Earth point to 10,000 TONS/YR !!!
We are presently located in an inter-arm (relatively low-density) region of
the Galaxy. Each ~70 to 140 million years the solar system traverses a
spiral arm region of much higher stellar and gas density. At each crossing
of the Sun through a spiral arm, the flux of dust and gas of extra-solar
origin arriving on top of terrestrial atmosphere will increase by many
orders of magnitude.
The Panspermia hypothesis might thus be much more efficient. Microbes
coming from other places in the CONTAMINATED GALAXY could use
dust grains and micrometeorites as natural vehicles and benefit of the
shielding effect operated by MICROPARTICULATE material. Living
organisms could have more intensively seeded Earth during crossings of
the solar system through dense galactic regions because of shorter
times required for any organism to reach Earth.
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IN CONCLUSION,
Micro-organisms could function as “minimal”
organization spreading life in many planetary systems.
biological
Microbial life could give birth to complex life, upon reaching a
minimally viable planet/moon.
The ability of extremophile organisms to cope with environmental
conditions far beyond conceivable limits should broaden the
astronomical concept of HABITABLE ZONE to a biological one, the
EXTREMOPHILE ZONE (EZ).
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Brazilian team:
MSc Ivan PAULINO-LIMA
Dr. João Alexandre R. G. BARBOSA1
Dr. Arnaldo Naves de BRITO1
Prof. Dr. Eduardo JANOT-PACHECO3
Dr Douglas GALANTE3
Gabriel DALMASO
Nacional de Luz Síncrotron – MCT/CNPq
2Instituto de Física – IF/UFRJ
3Departamento de Astronomia – IAG/USP
1Laboratório
B
International co-operation:
Dr. Nigel MASON, Open University, UK
Dr. Charles COCKELL, Open University, UK
Armando AZUA-BUSTOS, Univ Católica Chile
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SAB 03 set 2007
THANK YOU
KEEP
WATCHING...
Absence of evidence is not evidence of absence
Considering the immense Universe and the infinity
of time, it is a joy for me to share a planet and a
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time with you…
Carl Sagan
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