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Coupled phases and combinatorial selection in fluctuating hydrothermal pools: a scenario to guide experimental approaches to the origin of cellular life.

Damer B, Deamer D - Life (Basel) (2015)

Bottom Line: Two kinds of selective processes can then occur.The second is a chemical process in which rare combinations of encapsulated polymers form systems capable of capturing energy and nutrients to undergo growth by catalyzed polymerization.Given continued cycling over extended time spans, such combinatorial processes will give rise to molecular systems having the fundamental properties of life.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomolecular Engineering. bdamer@ucsc.edu.

ABSTRACT
Hydrothermal fields on the prebiotic Earth are candidate environments for biogenesis. We propose a model in which molecular systems driven by cycles of hydration and dehydration in such sites undergo chemical evolution in dehydrated films on mineral surfaces followed by encapsulation and combinatorial selection in a hydrated bulk phase. The dehydrated phase can consist of concentrated eutectic mixtures or multilamellar liquid crystalline matrices. Both conditions organize and concentrate potential monomers and thereby promote polymerization reactions that are driven by reduced water activity in the dehydrated phase. In the case of multilamellar lipid matrices, polymers that have been synthesized are captured in lipid vesicles upon rehydration to produce a variety of molecular systems. Each vesicle represents a protocell, an "experiment" in a natural version of combinatorial chemistry. Two kinds of selective processes can then occur. The first is a physical process in which relatively stable molecular systems will be preferentially selected. The second is a chemical process in which rare combinations of encapsulated polymers form systems capable of capturing energy and nutrients to undergo growth by catalyzed polymerization. Given continued cycling over extended time spans, such combinatorial processes will give rise to molecular systems having the fundamental properties of life.

No MeSH data available.


Related in: MedlinePlus

Vesicle formation during hydration phase. INSET: vesicles 10–20 mm in diameter bud from a dried mixture of phospholipid and DNA stained with acridine orange.
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life-05-00872-f005: Vesicle formation during hydration phase. INSET: vesicles 10–20 mm in diameter bud from a dried mixture of phospholipid and DNA stained with acridine orange.

Mentions: In the hydration cycle, vesicles are produced when the water interacts with the dry multilamellar matrix (Figure 5). Some vesicles contain polymers while others are empty [19]. It can be calculated that trillions of vesicles having diameters in the range of typical bacteria are produced from a few milligrams of amphiphiles. Significantly, each vesicle has a different composition from all the rest, allowing a natural version of combinatorial chemistry in which a few vesicles survive while most are dispersed. In regard to the differences that make each vesicle unique, suppose that there are ten different species of amphiphilic components that vary by chain length from 10 to 14 carbons in length, and these have two different head groups, for instance, carboxylate (–COO−) and hydroxyl (–OH). The amphipliles form vesicles ranging from 0.5 to 5.0 micrometers in diameter, which are mixed with ten different species of monomers such as amino acids and nucleotides that combine into random sequence polymers having lengths varying from ten to 100 subunits. Simple arithmetic reveals that the number of combinations will be immense. We also note that some of the polymers have the potential to fold into catalytically active conformations, adding another layer of complexity.


Coupled phases and combinatorial selection in fluctuating hydrothermal pools: a scenario to guide experimental approaches to the origin of cellular life.

Damer B, Deamer D - Life (Basel) (2015)

Vesicle formation during hydration phase. INSET: vesicles 10–20 mm in diameter bud from a dried mixture of phospholipid and DNA stained with acridine orange.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4390883&req=5

life-05-00872-f005: Vesicle formation during hydration phase. INSET: vesicles 10–20 mm in diameter bud from a dried mixture of phospholipid and DNA stained with acridine orange.
Mentions: In the hydration cycle, vesicles are produced when the water interacts with the dry multilamellar matrix (Figure 5). Some vesicles contain polymers while others are empty [19]. It can be calculated that trillions of vesicles having diameters in the range of typical bacteria are produced from a few milligrams of amphiphiles. Significantly, each vesicle has a different composition from all the rest, allowing a natural version of combinatorial chemistry in which a few vesicles survive while most are dispersed. In regard to the differences that make each vesicle unique, suppose that there are ten different species of amphiphilic components that vary by chain length from 10 to 14 carbons in length, and these have two different head groups, for instance, carboxylate (–COO−) and hydroxyl (–OH). The amphipliles form vesicles ranging from 0.5 to 5.0 micrometers in diameter, which are mixed with ten different species of monomers such as amino acids and nucleotides that combine into random sequence polymers having lengths varying from ten to 100 subunits. Simple arithmetic reveals that the number of combinations will be immense. We also note that some of the polymers have the potential to fold into catalytically active conformations, adding another layer of complexity.

Bottom Line: Two kinds of selective processes can then occur.The second is a chemical process in which rare combinations of encapsulated polymers form systems capable of capturing energy and nutrients to undergo growth by catalyzed polymerization.Given continued cycling over extended time spans, such combinatorial processes will give rise to molecular systems having the fundamental properties of life.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomolecular Engineering. bdamer@ucsc.edu.

ABSTRACT
Hydrothermal fields on the prebiotic Earth are candidate environments for biogenesis. We propose a model in which molecular systems driven by cycles of hydration and dehydration in such sites undergo chemical evolution in dehydrated films on mineral surfaces followed by encapsulation and combinatorial selection in a hydrated bulk phase. The dehydrated phase can consist of concentrated eutectic mixtures or multilamellar liquid crystalline matrices. Both conditions organize and concentrate potential monomers and thereby promote polymerization reactions that are driven by reduced water activity in the dehydrated phase. In the case of multilamellar lipid matrices, polymers that have been synthesized are captured in lipid vesicles upon rehydration to produce a variety of molecular systems. Each vesicle represents a protocell, an "experiment" in a natural version of combinatorial chemistry. Two kinds of selective processes can then occur. The first is a physical process in which relatively stable molecular systems will be preferentially selected. The second is a chemical process in which rare combinations of encapsulated polymers form systems capable of capturing energy and nutrients to undergo growth by catalyzed polymerization. Given continued cycling over extended time spans, such combinatorial processes will give rise to molecular systems having the fundamental properties of life.

No MeSH data available.


Related in: MedlinePlus