Re: Life With Bacteria Tamil Dubbed Movie Torrent
Nelson Suggs
The theory of a chemoautotrophic origin of life in a volcanic iron-sulphur world postulates a pioneer organism at sites of reducing volcanic exhalations. The pioneer organism is characterized by a composite structure with an inorganic substructure and an organic superstructure. Within the surfaces of the inorganic substructure iron, cobalt, nickel and other transition metal centres with sulphido, carbonyl and other ligands were catalytically active and promoted the growth of the organic superstructure through carbon fixation, driven by the reducing potential of the volcanic exhalations. This pioneer metabolism was reproductive by an autocatalytic feedback mechanism. Some organic products served as ligands for activating catalytic metal centres whence they arose. The unitary structure-function relationship of the pioneer organism later gave rise to two major strands of evolution: cellularization and emergence of the genetic machinery. This early phase of evolution ended with segregation of the domains Bacteria, Archaea and Eukarya from a rapidly evolving population of pre-cells. Thus, life started with an initial, direct, deterministic chemical mechanism of evolution giving rise to a later, indirect, stochastic, genetic mechanism of evolution and the upward evolution of life by increase of complexity is grounded ultimately in the synthetic redox chemistry of the pioneer organism.
A new study in the journal Small, which covers nanotechnology, shares the results from using spore-forming bacteria similar to the previous ingestible version to create a device that potentially would still work after 100 years.
The dime-sized fuel cell was sealed with a piece of Kapton tape, a material that can withstand temperatures from -500 to 750 degrees Fahrenheit. When the tape was removed and moisture allowed in, the bacteria mixed with a chemical germinant that encouraged the microbes to produce spores. The energy from that reaction produced enough to power an LED, a digital thermometer or a small clock.
Heat activation of the bacterial spores cut the time to full power from 1 hour to 20 minutes, and increasing the humidity led to higher electrical output. After a week of storage at room temperature, there was only a 2% drop in power generation.
Interaction of microbes with their environment depends on features of the dynamic microbial surface throughout cell growth and division. Surface modifications, whether used to acquire nutrients, defend against other microbes, or resist the pressures of a host immune system, facilitate adaptation to unique surroundings. The release of bioactive membrane vesicles (MVs) from the cell surface is conserved across microbial life, in bacteria, archaea, fungi, and parasites. MV production occurs not only in vitro but also in vivo during infection, underscoring the influence of these surface organelles in microbial physiology and pathogenesis through delivery of enzymes, toxins, communication signals, and antigens recognized by the innate and adaptive immune systems. Derived from a variety of organisms that span kingdoms of life and called by several names (membrane vesicles, outer membrane vesicles [OMVs], exosomes, shedding microvesicles, etc.), the conserved functions and mechanistic strategies of MV release are similar, including the use of ESCRT proteins and ESCRT protein homologues to facilitate these processes in archaea and eukaryotic microbes. Although forms of MV release by different organisms share similar visual, mechanistic, and functional features, there has been little comparison across microbial life. This underappreciated conservation of vesicle release, and the resulting functional impact throughout the tree of life, explored in this review, stresses the importance of vesicle-mediated processes throughout biology.
The gaseous nutrients enter the so-called intermediary metabolism of the extant organisms and form a few hundred low-molecular bioorganic compounds, which constitute the second category of molecular complexity. This may be seen as the chemically creative part of biochemistry. The gaseous nutrients enter synthetic pathways with redox reactions and thoroughgoing transformations of the electron configurations.
Some of the low-molecular bioorganic compounds are bifunctional monomers (e.g. amino acids), capable of undergoing polycondensations to high-molecular polymers, such as proteins or nucleic acids. This constitutes the third category of molecular complexity. It is not so much a chemically creative stage as an organizational stage, in which the monomers are merely combined covalently and sequentially without undergoing redox changes or substantial changes of their electron configurations. The fourth category of complexity is made up of particles: aggregates of several polymer molecules as such or embedded in a lipid membrane.
Such a pioneer organism may be seen as having a remarkable combination of three capabilities: for growth, reproduction and evolution. These central aspects of life coincide in the pioneer organism within one single type of process. This process may be briefly stated as follows. The thermodynamic driving force is provided by the chemical potential of the volcanic exhalations in the water phase. The kinetic reactivity is provided by the catalytic activity of the transition metal centres in or on the surfaces of the inorganic substructure. The combination of these thermodynamic and kinetic aspects has the following effects:
These proposals are highly compatible with the theory of a chemoautotrophic origin of life as presented here, which assumes high pressure (Wächtershäuser 1988d, 1992), elevated temperatures (above or around 100C), (Fe,Ni)-catalysis and the chemical potential of volcanic exhalations.
Let us now address two specific aspects of a possible cradle of life within the Hadean habitats that have been characterized earlier: hydrothermal systems and volcanic exhalations. These two aspects frequently occur side by side and are often confounded. The hydrothermal systems are cyclic. Ocean water cycles through the crust transporting heat and leached soluble salts from the crust into the ocean. For the origin of life they are of lesser importance. Volcanic exhalations are linear and hence primary, virgin magmatic gases (H2O, CO2, CO, H2S, etc.) escape as volcanic exhalations from the interior of the mantle. These, upon cooling, provide the chemical potential for the origin of life. Therefore, they form an indispensable part of the present theory, which means that the original homestead of life is situated in a volcanic flow system (Wächtershäuser 1988d). A Hadean volcanic flow system may be conceptually classified into three ideal types of flow regions:
Geochromatography has been previously invoked in conjunction with a prebiotic broth (Wing & Bada 1991, 2000) or with aquifers (Washington 2000). Corliss (1986) has analysed possible flow reactor conditions of a submarine hydrothermal vent. Subsequently, a number of other geologists have explored possible Hadean/Archaean hydrothermal vent scenarios for the origin of life (Russell et al. 1989, 1998, 2003, 2005; Holm 1992; Matsuno 1997; Russell & Hall 1997; Holm & Andersson 1998; Shock et al. 1998).
These reactants suggest a number of simple, testable reactions of volcanic nutrients in the formation and growth of a pioneer organism. These reactions may take place at the site of the pioneer organism for immediate infiltration into its surface metabolism or upstream thereof with subsequent transport of their products to the site of the pioneer organism. The following reactions have been experimentally demonstrated:
We may conceptualize ligand feedback from a different point of view. All products of the surface metabolism form a mixture (or library) of chemical compounds. Some may bond to the surface more or less strongly and others may not bond at all. Presently, from this library, the pioneer organism will automatically select those compounds, which are capable of bonding as ligands by selective residence or retention time; and optionally by protection from hydrolysis. In this sense, the products of the pioneer metabolism are self-selective. Increase in the size of the library of products increases the likelihood that it contains self-selecting ligands with autocatalytic feedback. Incidentally, from this point of view, racemates of the organic products of the pioneer metabolism mean a higher number of structures and thus a higher likelihood of positive feedback, which means that at this early stage of life lack of enantioselectivity of the synthetic reactions is an advantage rather than a disadvantage.
Today almost all the peptides and proteins are synthesized by ribosomal catalysis. As a simple specific model en route to the ribosomal machinery, let us assume surface-bonded pro-tRNAs in the form of nucleic acid hairpin structures that became aminoacylated terminally by activated amino acids. Let us further assume that two of these surface-bonded pro-tRNAs became located side by side and attached by base pairing with their loops to a surface-bonded nucleic acid strand as pro-mRNA. The result of this base pair-assisted anchimeric positioning is a more efficient synthesis of dipeptides to be followed later by oligopeptides. This is the origin of the simplest ribosomal machinery consisting of two pro-tRNAs and one pro-mRNA. It embodies the chemical (as opposed to organizational) core of the ribosomal process of translation.
In the context of a chemoautotrophic origin of life, we come to a drastically different conclusion. Here, the two processes of sequence control, those of replication and translation, must have become established jointly, by coevolution (cf. Lahav 1999), whereby the emergence and evolution of replication slightly trailed the emergence and the evolution of translation. Each new increment of added potential sequence selectivity of translation would have served as the functional advantage for a subsequent increment of added sequence fidelity of template-directed nucleic acid synthesis. In the course of this coevolution of translation and replication, the primary, direct, chemical mechanism of evolution by variation of the synthesis of peptides with direct autocatalytic feedback became first supplemented and later increasingly substituted by a secondary, indirect, genetic mechanism of evolution, whereby variations of replicating nucleic acid sequences led indirectly to variations of peptide sequences. This transformation led to a step-by-step replacement of primitive metallo-peptides by more and more complex coded metallo-peptides. It was the basis for the admission of more diversified amino acids into the system and for the establishment and expansion of the genetic code. The conclusion seems to be inescapable: the evolution of nucleic acid replication and of nucleic acid-catalysed peptide synthesis must have been intrinsically linked. This conclusion is in sharpest contrast to all the notions of a world of RNA life with RNA replication and without translation (cf. Forterre 2005).
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