Aqueous magnesium as an environmental selection pressure in the evolution of phospholipid membranes on early earth

Dalai, Punam; Ustriyana, Putu; Sahai, Nita

doi:10.1016/j.gca.2017.11.034

Cited by 23 publications

(26 citation statements)

References 59 publications

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“…Therefore, a decrease in the net negative charge on the vesicle surface would lead to a weakening in the interaction with the Mg 2+ ions. It has been previously shown that, addition of phospholipids to oleic acid membranes can decrease the zeta potential of the membranes, which in turn stabilizes the fatty acid membranes in the presence of Mg 2+ ions (26). The zeta potential measurements (SI, method 2.7) revealed that addition of UDG to the UDA membrane, decreased the net negative charge density, as shown in Figure 8B.…”

Section: Mechanism By Which Compositional Heterogeneity Might Confer mentioning

confidence: 68%

“…Optical microscopy and dynamic light scattering spectroscopy (DLS), was used to check the stability of the vesicles in the presence of Mg 2+ ions (SI, Method 2.5,). The concentration of Mg 2+ ion at which the average size of the vesicle population increases, in comparison to the initial size (when no Mg 2+ is added), was considered to be the aggregation-inducing concentration (Mg 2+ AIC) (26). At this concentration, both, vesicles and Mg 2+ induced aggregates can be present simultaneously in the solution ( Figure 5).…”

Section: Effect Of Membrane Heterogeneity On Its Stability In the Prmentioning

confidence: 99%

“…In order to understand the effect that each head group might have on the permeability of model protocell membranes, calcein leakage assay was carried out using the four different C11:1 systems (SI, Method 2.6). Calcein, a small charged molecule, was encapsulated in the different vesicular systems, at a concentration above its self-quenching concentration, and its release was measured over time (26). It was observed that when gyceryl 1-undecylenate (UDG) was mixed with undecylenic acid (UDA), the permeability of the system (C11_2:1_UDG) for calcein increased in comparison to the homogenous C11_UDA membrane system.…”

Section: Influence Of Compositional Heterogeneity On the Permeabilitymentioning

confidence: 99%

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Compositional heterogeneity confers selective advantage to protocellular membranes during the origins of cellular life

Sarkar

Dagar

Verma

et al. 2019

Preprint

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Protocell membranes are considered the boundaries of cellular life that first emerged on the prebiotic Earth. They are thought to be comprised of mixtures of single chain amphiphiles, such as fatty acids and their derivatives, moieties which would have been part of the complex prebiotic chemical landscape. In addition to their composition, the physico-chemical properties of these prebiological membranes would have been significantly affected, and regulated, by the physical environment that they were present in. In this study, the physico-chemical properties of two different chain length membrane systems, were systematically characterized, under prebiotically pertinent environmental conditions. The membrane systems have been designed to be composed of fatty acid and/or their alcohol and glycerol monoester derivatives, to make a range of vesicle combinations (e.g. binary and tertiary systems). Their properties were evaluated as a function of multiple factors including their composition, stability under varying pH, Mg 2+ ion concentration and dilution regimes, and permeability. These environmental constraints would have acted as important prebiotic selection pressures to shape the evolution of prebiological membranes. Our results indicate that complex membrane systems are more stable and robust to multiple selection pressures, thereby making them more suitable for supporting protocellular life. Furthermore, different fatty acid derivatives conferred varying degrees of stability when mixed with their respective fatty acid moiety. Importantly, the aforesaid depended on the chain length of the system, and the selection pressure that was applied. Significantly, when the systems were subjected to multiple selection pressures in a consecutive manner, only the heterogeneous membrane systems survived the race. These results highlight the requirement of compositional complexity, and underscore its implications for the emergence of mixed membrane systems during the dawn of life on Earth.

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Section: Mechanism By Which Compositional Heterogeneity Might Confer mentioning

confidence: 68%

Section: Effect Of Membrane Heterogeneity On Its Stability In the Prmentioning

confidence: 99%

Section: Influence Of Compositional Heterogeneity On the Permeabilitymentioning

confidence: 99%

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Compositional heterogeneity confers selective advantage to protocellular membranes during the origins of cellular life

Sarkar

Dagar

Verma

et al. 2019

Preprint

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“…Indeed, as Lane has noted in discussing the the adenosine triphosphate (ATP) synthase conversion engine, they can accurately be said to “transcend” chemistry–as we mentioned above. For these reasons alone, all “life is chemistry in a bag” notions, must fail.…”

Section: Energy Warm Ponds Hot Soups: Which Idea Animates Essentialmentioning

confidence: 99%

Frankenstein or a Submarine Alkaline Vent: Who Is Responsible for Abiogenesis?

Branscomb

Russell

2018

BioEssays

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Origin of life models based on "energized assemblages of building blocks" are untenable in principle. This is fundamentally a consequence of the fact that any living system is in a physical state that is extremely far from equilibrium, a condition it must itself build and sustain. This in turn requires that it carries out all of its molecular transformations-obligatorily those that convert, and thereby create, disequilibria-using case-specific mechanochemical macromolecular machines. Mass-action solution chemistry is quite unable to do this. We argue in Part 2 of this series that this inherent dependence of life on disequilibria-converting macromolecular machines is also an obligatory requirement for life at its emergence. Therefore, life must have been launched by the operation of abiotic macromolecular machines driven by abiotic, but specifically "life-like", disequilibria, coopted from mineral precipitates that are chemically and physically active. Models grounded in "chemistry-in-a-bag" ideas, however energized, should not be considered.

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“…[238,255] Superior to lipids -which anyway are 'costly' to make, suffer the disadvantage of their impermeability, and likely evolved later -they maintain the capability of proto-enzymetic activity. [133,238,242,256,257] 9. Ligand-assisted autocatalysis and 'Protoenzymes' (Table 1) 5 to 6-mer alanine nests sequestering anionic clusters of the iron oxyhydroxides and sulfides, could also have played an essential role in mineral redox-powered disequilibriaconverting engines driving ligand-accelerated autocatalytic reactions.…”

Section: The Peptide and Amyloid Takeover?mentioning

confidence: 99%

Green Rust: The Simple Organizing ‘Seed’ of All Life?  <strong> </strong>

Russell

2018

Preprint

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The most important problem of synthetic biology is…the reduction of carbonic acid. and Without the idea of spontaneous generation and a physical theory of life, the doctrine of evolution is a mutilated hypothesis without unity or cohesion.[1] Leduc, [1]Abstract: Korenaga and coworkers present evidence to suggest that 4.3 billion years ago the Earth's mantle was dry and water filled the ocean to twice its present volume.[2] CO2 was constantly exhaled during the mafic to ultramafic volcanic activity associated with magmatic plumes that produced the thick, dense and relatively stable oceanic crust. In that setting two distinct major types of sub-marine hydrothermal vents were active: ~400°C acidic springs whose effluents bore vast quantities of iron into the ocean, and ~120°C, highly alkaline and reduced vents exhaling from the cooler, serpentinizing crust at some distance from the heads of the plumes. When encountering the alkaline effluents, the iron from the plume head vents precipitated out forming mounds likely surrounded by voluminous exhalative deposits similar to the banded iron formations known from the Archean. These mounds and the surrounding sediments likely comprising nanocrysts of the variable valence FeII/FeIII oxyhydroxide, green rust. The precipitation of green rust, along with subsidiary iron sulfides and minor concentrations of Ni, Co and Mo in the environment at the alkaline springs may have established both the key bio-syntonic disequilibria, and the means to properly make use of them -those needed to drive the essential inanimate-to-animate transitions that launched life. In the submarine alkaline vent model for the emergence of life specifically it is first suggested that the redox-flexible green rust microcrysts spontaneously formed precipitated barriers to the complete mixing of carbonic ocean and alkaline hydrothermal fluids, barriers that created and maintained steep ionic disequilibria; and second, that the hydrous interlayers of green rust acted as 'engines' that were powered by those ionic disequilibria and drove essential endergonic reactions. There, aided by sulfides and trace elements acting as catalytic promoters and electron transfer agents, nitrate could be reduced to ammonia and carbon dioxide to formate, while methane may have been oxidized to methyl and formyl groups. Acetate and higher carboxylic acids could then have been produced from these C1 molecules and aminated to amino acids, and thence oligomerized to offer peptide nests to phosphate and iron sulfides and secreted to form primitive amyloid-bounded structures, leading conceivably to protocells.

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Aqueous magnesium as an environmental selection pressure in the evolution of phospholipid membranes on early earth

Cited by 23 publications

References 59 publications

Compositional heterogeneity confers selective advantage to protocellular membranes during the origins of cellular life

Compositional heterogeneity confers selective advantage to protocellular membranes during the origins of cellular life

Frankenstein or a Submarine Alkaline Vent: Who Is Responsible for Abiogenesis?

Green Rust: The Simple Organizing ‘Seed’ of All Life?  <strong> </strong>

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Aqueous magnesium as an environmental selection pressure in the evolution of phospholipid membranes on early earth

Cited by 23 publications

References 59 publications

Compositional heterogeneity confers selective advantage to protocellular membranes during the origins of cellular life

Compositional heterogeneity confers selective advantage to protocellular membranes during the origins of cellular life

Frankenstein or a Submarine Alkaline Vent: Who Is Responsible for Abiogenesis?

Green Rust: The Simple Organizing &lsquo;Seed&rsquo; of All Life?&nbsp;&nbsp;<strong> </strong>

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Green Rust: The Simple Organizing ‘Seed’ of All Life? <strong> </strong>