scholarly journals Hydrothermal Conditions and the Origin of Cellular Life

Astrobiology ◽  
2015 ◽  
Vol 15 (12) ◽  
pp. 1091-1095 ◽  
Author(s):  
David W. Deamer ◽  
Christos D. Georgiou
Keyword(s):  
Hydrothermal Conditions ◽  
Cellular Life

Cycles, Compartments, and Polymerization

2019 ◽  
Author(s):  
David W. Deamer
Keyword(s):  
Genetic Information ◽  
Hydrothermal Vents ◽  
Carbon Fixation ◽  
Energy Sources ◽  
Hydrothermal Conditions ◽  
Biologically Relevant ◽  
Cellular Life ◽  
Primitive Metabolism ◽  
Chain Lengths ◽  
Design Experiments

The two quotes in the epigraph, in juxtaposition, always make me smile, and I tried to keep them in mind while writing this chapter. The first eight chapters of this book have the effect of eliminating the impossible by investigating the facts to which Twain is referring. Perhaps he would consider them trifling, but I doubt that Twain ever performed an experiment to test an idea. Every working scientist knows that science is not just a set of facts but is also a set of questions. The best way to begin answering a question is to pose a hypothesis and that hypothesis begins as a conjecture. Only when we have a hypothesis, can we design experiments to test it, and if we are lucky, the results of those experiments lead us a little closer to the truth. This chapter summarizes facts that lead to an alternative scenario for life’s origin in freshwater hydrothermal conditions rather than a marine origin in saltwater hydrothermal vents. As stated in the introduction to this book, when assumptions are part of the story they will be made explicit so that the logic that arises from them will be clear. What follows in this overview is a list of ten prerequisites we assume are necessary for cellular life to begin, followed by eight assumptions underlying the scenario to be presented here. Prerequisite conditions for life to begin: Dilute solutions of potential reactants are available, together with a process by which they can be sufficiently concentrated to react. Energy sources available in the environment can drive reactions such as carbon fixation, primitive metabolism, and polymerization. Products of reactions accumulate within the site rather than dispersing into the bulk phase environment. Amphiphiles assemble into membranous compartments over the range of temperatures, salt concentrations, and pH values related to each site. Biologically relevant polymers are synthesized with chain lengths sufficient to act as catalysts or incorporate genetic information. A plausible physical mechanism can produce encapsulated polymers as protocells then subject them to combinatorial selection. Organic solutes in aqueous solutions become biochemical solutes within protocells and then substrates supporting a primitive metabolism.

Dynamics of CO2 emission from chernozems under agricultural use

2017 ◽  
Vol 4 (3) ◽  
pp. 43-49
Author(s):  
M. Miroshnychenko ◽  
O. Siabruk
Keyword(s):  
Carbon Dioxide ◽  
Agricultural Practices ◽  
Growing Season ◽  
Warm Period ◽  
Direct Seeding ◽  
Soil Tillage ◽  
Plant Residues ◽  
Hydrothermal Conditions ◽  
Organic Mineral ◽  
Mineral System

Aim. The comparison of the effect of hydrothermal conditions and various agricultural practices on the emission of CO 2 from chernozems in the Left-Bank Forest-Steppe of Ukraine. Methods. The dynamics of the intensity of carbon dioxide emissions from chernozem calcic (typical chernozem – in Ukrainian classifi cation) was studied during the growing season of 2011–2012. The observations were based on two fi eld experiments with various methods of soil till- age (6–7 years from the beginning of the experiment) and fertilization systems (21–22 years from the beginning of the experiment). Particularly, plowing at 20–22 cm, disking at 10–12 cm, cultivation at 6–8 cm and direct seeding using Great Plains drill were studied among the soil tillage methods. Mineral system (N 45 P 50 K 45 ), organic system (manure 8 t/ha) and combined organic-mineral system (manure 8 t/ha + N 45 P 50 K 45 ) were studied among fertilization systems. The intensity of CO 2 fl ux was determined using the non-stationary respiratory chambers by the alkaline absorption method, with averaging of the results during the day and the frequency of once a month. Results. During the warm period, the emission of carbon dioxide from the soil changes dynamically depending on temperature and humidity. The maximum of emission coincides with the periods of warm summer showers in June-July, the minimum values are characteristic for the late autumn period. The total emission losses of carbon in chernozems over the vegetation period ranged from 480 to 910 kg/ha and varied depending on the methods of tillage ± (4.0–6.0) % and fertilization systems ± (3.8–7.1) %. The changes in the intensity of CO 2 emission from the soil under different methods of soil tillage are associated with hydrothermal regime and the depth of crop residues location. The biggest difference is observed im- mediately after tillage, but in the spring period the differences are only 12–25 %, and after drying of the top layer of soil become even less. Direct seeding technology provides the greatest emission of CO 2 from chernozem, which is fa- cilitated by better water regime and more complete mineralization of plant residues on the soil surface. Annual losses of carbon are the least under disking of soil at 10–12 cm. The changes in the intensity of CO 2 emission from the soil under different fertilization systems are associated with the involvement of the additional organic matter from plant residues and manure to the microbiological decomposition. The greatest emission was observed under the organic- mineral fertilization system, which increased the loss of carbon by 7–8 % in comparison with the mineral system in the unfavorable hydrothermal year and by 11–15 % in the more favorable year. These differences are observed mainly during the fi rst half of the growing season when there is a clear tendency to increase the intensity of soil respiration. Conclusions. The hydrothermal conditions of the warm period of the year are decisive in the formation of the CO 2 emission fl ow from chernozems. Due to the improvement of agricultural practices, emissions might be reduced but not more that by 15 % of natural factor contribution.

A common precursor to both prebiotic and biological pathways to RNA nucleotides

2018 ◽  
Author(s):  
Andrea Pérez-Villa ◽  
Thomas Georgelin ◽  
Jean-François Lambert ◽  
Marie-Christine Maurel ◽  
François Guyot ◽  
...  
Keyword(s):  
Enzymatic Synthesis ◽  
De Novo ◽  
Life Forms ◽  
Hydrothermal Conditions ◽  
Modern Life ◽  
Ab Initio Simulations ◽  
Spontaneous Formation ◽  
Common Precursor ◽  
Open Issue ◽  
Anomeric Carbon

Understanding the mechanism of spontaneous formation of ribonucleotides under realistic prebiotic conditions is a key open issue of origins-of-life research. In cells, <i>de novo</i> and salvage nucleotide enzymatic synthesis combines 5-phospho-α -D-ribose-1-diphosphate ( α-PRPP) and nucleobases. Interestingly, these reactants are also known as prebiotically plausible compounds. Combining ab initio simulations with mass spectrometry experiments, we compellingly demonstrate that nucleobases and α -PRPP spontaneously combine, through the same facile mechanism, forming both purine and pyrimidine ribonucleotides, under mild hydrothermal conditions. Surprisingly, this mechanism is very similar to the biological one, and yields ribonucleotides with the same anomeric carbon chirality as in biological systems. These results suggest that natural selection might have optimized – through enzymes – a pre-existing ribonucleotide formation mechanism, carrying it forward to modern life forms.

A common precursor to both prebiotic and biological pathways to RNA nucleotides

2017 ◽  
Author(s):  
Andrea Pérez-Villa ◽  
Thomas Georgelin ◽  
Jean-François Lambert ◽  
Marie-Christine Maurel ◽  
François Guyot ◽  
...  
Keyword(s):  
Enzymatic Synthesis ◽  
De Novo ◽  
Life Forms ◽  
Hydrothermal Conditions ◽  
Modern Life ◽  
Ab Initio Simulations ◽  
Spontaneous Formation ◽  
Common Precursor ◽  
Open Issue ◽  
Anomeric Carbon

Understanding the mechanism of spontaneous formation of ribonucleotides under realistic prebiotic conditions is a key open issue of origins-of-life research. In cells, <i>de novo</i> and salvage nucleotide enzymatic synthesis combines 5-phospho-α -D-ribose-1-diphosphate ( α-PRPP) and nucleobases. Interestingly, these reactants are also known as prebiotically plausible compounds. Combining ab initio simulations with mass spectrometry experiments, we compellingly demonstrate that nucleobases and α -PRPP spontaneously combine, through the same facile mechanism, forming both purine and pyrimidine ribonucleotides, under mild hydrothermal conditions. Surprisingly, this mechanism is very similar to the biological one, and yields ribonucleotides with the same anomeric carbon chirality as in biological systems. These results suggest that natural selection might have optimized – through enzymes – a pre-existing ribonucleotide formation mechanism, carrying it forward to modern life forms.

A Survey on Computational Methods for Essential Proteins and Genes Prediction

2019 ◽  
Vol 14 (3) ◽  
pp. 211-225 ◽  
Author(s):  
Ming Fang ◽  
Xiujuan Lei ◽  
Ling Guo
Keyword(s):  
Computational Methods ◽  
Drug Targets ◽  
Disease Genes ◽  
Essential Proteins ◽  
Experimental Identification ◽  
Cellular Life ◽  
Different Types ◽  
The Stability ◽  
Human Disease Genes ◽  
Biology Research

Background: Essential proteins play important roles in the survival or reproduction of an organism and support the stability of the system. Essential proteins are the minimum set of proteins absolutely required to maintain a living cell. The identification of essential proteins is a very important topic not only for a better comprehension of the minimal requirements for cellular life, but also for a more efficient discovery of the human disease genes and drug targets. Traditionally, as the experimental identification of essential proteins is complex, it usually requires great time and expense. With the cumulation of high-throughput experimental data, many computational methods that make useful complements to experimental methods have been proposed to identify essential proteins. In addition, the ability to rapidly and precisely identify essential proteins is of great significance for discovering disease genes and drug design, and has great potential for applications in basic and synthetic biology research. Objective: The aim of this paper is to provide a review on the identification of essential proteins and genes focusing on the current developments of different types of computational methods, point out some progress and limitations of existing methods, and the challenges and directions for further research are discussed.

SKARN-GARNET ARCHIVES OF METASOMATIC AND HYDROTHERMAL CONDITIONS IN THE MINERAL KING ROOF PENDANT, SOUTH-CENTRAL SIERRA NEVADA

2016 ◽  
Author(s):  
Juliet Ryan-Davis ◽  
◽  
Jade Star Lackey ◽  
Megan D'Errico ◽  
Kouki Kitajima ◽  
...  
Keyword(s):  
Sierra Nevada ◽  
Hydrothermal Conditions ◽  
South Central
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