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SELF-REPRODUCTION OF SYNTHETIC AND BIOLOGICALSYSTEMS

THE INCREASE OF COMPLEXITYTOWARDS THE EMERGENCE OF LIFEPROCEEDS

VIA THE INTERPLAY BETWEEN SELF-ORGANIZATION ANDEMERGENCE

SELF-ORGANIZATION: THE ACQUISITION OF HIGHER STRUCTURAL ORDER-AS DETERMINED BY THE SYSTEM’S RULES

…under thermodynamic or kinetic control

Emergence: the formation of a highercomplexity level brings about NOVEL propertiesthat are not present in the basic components

..the whole is morethan the sum of the parts...holism

ORIGIN OF SELF - REPRODUCTION

ORIGIN OF LIFE

" self " meansthat the structure itself does iti. e. , the process is autocatalytic

self - reproduction = autocatalysis

AND :

AND :

IF THE STRUCTURE CARRIES INFORMATION (A) ,THEN WE HAVEREPRODUCTION & INFORMATION AT A TIME

IF DURING SELF-REPRODUCTIONALSO STRUCTURAL ( FUNCTION ) CHANGES OCCUR,WE ALSO HAVE EVOLUTION NOVEL CATALYSIS

.....everything else

pairing of chromsomes and crossing over of chromosomes does occur

pairing of chromsomes does not occur

chromosome pairs align at metaphase plate

chromosome align independently

homologous chromosomes separate

daughter chromosomes

separate

daughter chromosomes

separate

daughter cells are not genetically identical to parent cells

daughter cells are genetically identical to parent cells

Comparison of meiosis and mitosis.

(The blue chromosomes were inherited from one parent, and the red chromosomes were inherited from other parent.)

(from Biology / S.Mader, 5th ed.)

A-DNA B-DNA Z-DNA

Original parent molecule

First generation daughter molecules

Second generation daughter molecules

Schematic diagram of semiconservativereplication. Parental DNA is shown in greenand newly synthesized DNA in red. [After M. Meselson and F.W. Stahl. Proc. Nat. Acad. Sci. 44(1958):671.)

DNA Double Helix________________________

Sugar: DeoxyriboseBases: Adenine (A), guanine (G) thymine (T), cytosine (C)Strands: Double stranded with base pairing

sugar-phosphatebackbone

sugar

hydrogen bonds

complementarybase pairing

2nm

0.34nm 3.4nm

parent molecule

newstrand

oldstrand

daughter moleculedaughter molecule

oldstrand

newstrand

In particular research focusses on

SELF-REPLICATION SYSTEMS

Self means that the process is spontaneous, i.e.,determined by the internal rule of the system

(generally self-replication corresponds to autocatalysis, and generally thetime process is exponential)

A 2A 4A 8A 16A etc

THE NON LINEARITYIn self-replication mechanisms

THE NON LINEARITYIn self-replication mechanisms

(how it works on paper)

a) heterocatalysisa) heterocatalysis

A BOne molecule per second, then 6.1023 sec. to makeone mole of B

b) self-replication (autocatalysis)b) self-replication (autocatalysis)

A AOnly 79 sec. to make one mole of A2.....4.....8.....16.....32.....64.....128......etc.

CHI VUOLE FARE UN BREVE STUDIOSULLA „FORMOSE REACTION“E RIFERIRE IN CLASSE?..USING GOOGLE...

THE FORMOSE REACTION AS AN AUTOCATALYTICPROCESS TO MAKE SUGARS?....IMPORTANCE FOR THE PREBIOTIC RNA-WORLD?

DNA Double Helix________________________

Sugar: DeoxyriboseBases: Adenine (A), guanine (G) thymine (T), cytosine (C)Strands: Double stranded with base pairing

sugar-phosphatebackbone

sugar

hydrogen bonds

complementarybase pairing

2nm

0.34nm 3.4nm

L. Orgel and coworkers, in the eighties

A B

M

D

T(2x)

K 1

kK 2

General mechanism for a minimal self-replicating system.Constituent A represents the activated form of trimer A2 here.Large arrowheads at the reaction arrows for the reversiblereactions indicate the favored site of the equilibrium.

G. Von Kiedrowski, Angew.chem. (1986) 10, 932

Rebek, JACS (1990)

Coupling of two self-replicataing systems...

Nicolau, 2001

Ghadiri, 2001

Also some peptides can self-replicate....

Model for a RNA-replicase

the notion of hypercycle, originally developed by Eigen and collaborators (Eigen 1971, Eigen and Schuster 1977, 1979).

A simple rendering of an hypercycle,

Fig. 4.6 The hypercycle. Each of the units A, B, C and D is a replicator. The rate of replication of each unit is an increasing function of the concentration unit immediately preceeding it. Thus the rate of replication of B is an increasing function of the concentration of A, and so on round the cycle.

Self-reproduction of supramolecualr aggregates

p.s. reproduction and replication are not the same thing...

Micelle

Liposome

Bilayer sheet

Cross-sectional views of the three structures that can be formed by mechanically dispersing a suspension of phospholipids in aqueous solution

The red circles depict the hydrophilic heads of phospholipids, and the squiggly lines (in the yellow region) the hydrophobic tails.

O

OH

O

O

O P

O

O

HO

O

ON

+

NO

OH

N

OOH

O NH2O

O

O

O

O P

O

O

H

Oleic acid / oleat vesicles

SELF-REPRODUCING MICELLES, LIPOSOMES

& CHEMICAL AUTOPOIESIS

etc.....

SELF - REPLICATING MICELLES

H2O

S

A ,B

S S S S SS

SSSSS

SS

S

SSSS

SS

SS S S S S

A A

A

A

A B S+

B B

B

B

SS S S S S S

SS

S

SS

SS

S

S

SS

S

SS S

S S S SS

A A

A

A

A B S+

B B

B

B

S S

S

SS

SS

S

S

S

S

S

S

S

SS S S S S

SS

SSSS

SS

S

SSSS

SS

SS S S S S

A A

A

A

A B+

B B

BB

SS S S S S

SS

SSSS

SS

S

SSSS

SS

SS S S S S

A A

A

A

A B+

B B

BB

waterpool

bulk solvent

etc.

etc.

LUISI & VARELAORIGIN OF LIFE 1990

a

b

caprylate COO-

oleate

or

CH3(CH2)7 -CH = CH-(CH2)7COO-

form micelles at alkaline pH

COO-

(Deamer, 1976)

vesicles at pH=7-8(pH pk)~_

COO- HOOC

precursors ( water insoluble! )

R CO

R COO

OH-

OH-

R COOR'

or

micelles or

R COO-

vesicles

... a reaction which creates its ownmicroenvironment for self-replication....

water insolubleETHYL CAPRYLATE

NaOH

H2O

Ethylcaprylate caprylatecmcOH-

micelles in water(pH ~ 10)

or vesicles (pH ~ 7 - 8)

(start with anhydride)

Hydrolysis of Caprylic anhydride

13

11

9

7

5

0 100 200 300 400 500Time ( hrs )

CA

pH

CAcac

CA

CA

CACA

CA CA

CA

morevesicles

fast CAhydrolysis

T = 40 °C

The hydrophobicity of the lipid bilayer

Is the main driving force for

The activity/reactivity and applications

Of liposomes

SS

SS

SSH2O

SS

S

excesswater-insolublesurfactant precursorbound to the bilayer

hydrolyzedon / bythe bilayer

largerunstableintermediates

forming moreof smaller stable vesicles

S

SS

SS

S

SS

S

SS

S

S

H2O

S

S

SS

SS S

S

H2O S

lipophilic bilayerof surfactant S

S

SS

SS S

S

H2O S

S

SS

SS S

S

H2O S

s-s

s-s

independentself - assembly

micelleslipid binding

size growth

numbergrowth

VESICLE GROWTH & REPRODUCTION

Cryo-TEM micrographs of(A) ferritin -containing POPC liposomes prepared using the reverse phase

evaporation method, followed by a sizing down by extrusion through polycarbonate membranes with 100 nm pore diameters ([POPC] = 6.1 mM); and of

(B) the vesicle suspension obtained after addition of oleate to preformed POPC liposomes ([POPC] = 3 mM, [oleic acid + oleate] = 3 mM).

A B

J. Phys. Chem. B 2001, 105, 1065-1071Nathalie Berclaz,

Schematic Representation of the Possible Vesicle Formation and Transformation Processes if Oleate (and Oleic Acid) Are Added to Preformed Vesicles Which Have Been Labelled with a Water-Soluble Marker

(I) shows the situation if only de novo vesicle formation occurs.

(II) illustrates a growth in size of the preformed and labelled vesicles which may lead to a splitting (fission process), either yielding vesicles which all contain marker molecules (case a, a statistical redistribution of the ferritin molecules is thus obtained) or yielding vesicles which do not all contain markers (case b). See text for details.

oleate (and oleic acid)

a b

(II) growth of the preformed vesicles eventually followedby a fission process

(I) de novo vesicle formation

oleate (and oleic acid)

J. Phys. Chem. B 2001, 105, No. 5, 1056-1064

Separation of nonentrapped ferritin molecules from ferritin-containing POPC vesicles using a Sepharose 4B column (length 50 cm, diameter 1.2 cm). The POPC vesicles were prepared in borate buffer (0.1 M, pH 8.5) by the reverse phase evaporation method, followed by a sizing down to about 100 nm by extrusion. The vesicle suspension applied onto the column had a volume of 0.45 mL, and fractions of 1 mL were collected. The open squares represent the POPC, and the filled circles represent the ferritin concentrations.

J. Phys. Chem. B 2001, 105, No. 5, 1056-1064

Number-weighted size distributions as obtained by cryo-TEM

(A) for the preformed POPC vesicles ([POPC] ) 1.9 mM) and

(B) for the vesicle suspension obtained upon addition of oleate to preformed ferritin-containing POPC vesicles ([POPC] ) 0.2 mM, [oleic acid + oleate] ) 5 mM). Empty (empty bars) and ferritin-containing (filled bars) vesicles are represented individually in the histogram.

(C) Direct comparison of the number-weighted size distribution of the preformed POPC vesicles which contained at least one ferritin molecule (filled bars) with the number-weighted size distribution of the ferritin-containing vesicles obtained after oleate addition to preformed POPC vesicles (empty bars). Note that the total of all ferritin-containing vesicles was set to 100%.

J. Phys. Chem. B 2001, 105, No. 5, 1056-1064

filled bars:

liposomes with ferritin

empty bars:

empty liposomes

(A) Number-weighted size distribution as obtained by cryo-TEM for the oleic acid vesicle suspension analyzed before hydrolysis (filled bars) and after oleic anhydride hydrolysis (empty bars).

(B) Number-weighted size distribution as obtained by cryo-TEM for the oleic acid vesicle suspension examined after oleic anhydride hydrolysis. Empty (empty bars) and ferritin-containing (filled bars) vesicles are represented individually.

(C) Comparison of the number-weighted size distribution of the filled oleic acid vesicles obtained before (filled bars) and after (empty bars) oleic anhydride hydrolysis. The total of all ferritin-containing vesicles was set to 100%. The last bar of the histogram in the three figures corresponds to all the vesicles larger than 300 nm.

J. Phys. Chem. B 2001, 105, No. 5, 1056-1064

filled bars:

liposomes with ferritin

empty bars:

empty liposomes

Nathalie

Nathalie Berclaz et al.,

Comparison of the “absolute” number-weighted size distribution(A) of the empty and(B) of the filled preformed POPC liposomes ([POPC] = 6.1 mM; black bars)

with the vesicles obtained after addition of oleate ([POPC] = 3 mM, [oleic acid + oleate] = 3 mM; empty bars).

0

5

10

15

20

25

30

35

40

45

0 50 100 150 200

vesicle diameter (nm)

arb

itra

ry u

nits

before

after

0

2

4

6

8

10

12

14

16

18

0 50 100 150 200

vesicle diameter (nm)

arb

itra

ry u

nits

before

after

A B

J. Phys. Chem. B 2001, 105, 1065-1071

0.00

0.10

0.20

0.30

0.40

0 50 100 150 200

time (min)

Spontaneous vesiculation and self-replication

buffer

neat surfactant

spontaneous

vesiculation

increasedsolubilisation

autocatalyticpopulationincrease

O

OH

oleic acidOD500 nm

Splicing_2nd_Example_SV3.avi

J. Phys. Chem. B J. Phys. Chem. B 1998, 1998, 102, 102, 7078-70807078-7080

O2N

OCH3

O P O

O

O

(CH2)9CH3

(CH2)9CH3 O P O

O

O

(CH2)9CH3

(CH2)9CH3-+K

O2N

OCH3

O K+-

spontaneousspontaneousformation offormation of

vesiclesvesicles

11 22 33

KOH 0.2 MKOH 0.2 M

hh++