scholarly journals Concurrent origins of the genetic code and the homochirality of life, and the origin and evolution of biodiversity. Part I: Observations and explanations

2015 ◽  
Author(s):  
Dirson Jian Li
Keyword(s):  
Genetic Code ◽  
Early History ◽  
Mass Extinctions ◽  
Genome Sequences ◽  
Origin And Evolution ◽  
New Methods ◽  
Evolution Of Life ◽  
History Of ◽  
Technical Details ◽  
Recruitment Order

The post-genomic era has brought opportunities to bridge traditionally separate fields on early history of life. New methods promote a deeper understanding of the origin of biodiversity. Relative stabilities of base triplexes are able to regulate base substitutions in triplex DNAs. We constructed a roadmap based on such a regulation to explain concurrent origins of the genetic code and the homochirality of life. Based on the recruitment order of codons in the roadmap and the complete genome sequences, we reconstructed the three-domain tree of life. The Phanerozoic biodiversity curve has been reconstructed based on genomic, climatic and eustatic data; this result supports tectonic cause of mass extinctions. Our results indicate that chirality played a crucial role in the origin and evolution of life. Here is Part I of my two-part series paper; technical details are in Part II of my paper (see “Concurrent origins of the genetic code and the homochirality of life, and the origin and evolution of biodiversity. Part II: Technical appendix” on bioRxiv).

scholarly journals The origins of modern biodiversity on land

2010 ◽  
Vol 365 (1558) ◽  
pp. 3667-3679 ◽  
Author(s):  
Michael J. Benton
Keyword(s):  
Regional Scale ◽  
Global Scale ◽  
Scale Model ◽  
Time Range ◽  
Geological Time ◽  
New Methods ◽  
Evolution Of Life ◽  
History Of ◽  
Extinction Events ◽  
Mass Extinction Events

Comparative studies of large phylogenies of living and extinct groups have shown that most biodiversity arises from a small number of highly species-rich clades. To understand biodiversity, it is important to examine the history of these clades on geological time scales. This is part of a distinct ‘phylogenetic expansion’ view of macroevolution, and contrasts with the alternative, non-phylogenetic ‘equilibrium’ approach to the history of biodiversity. The latter viewpoint focuses on density-dependent models in which all life is described by a single global-scale model, and a case is made here that this approach may be less successful at representing the shape of the evolution of life than the phylogenetic expansion approach. The terrestrial fossil record is patchy, but is adequate for coarse-scale studies of groups such as vertebrates that possess fossilizable hard parts. New methods in phylogenetic analysis, morphometrics and the study of exceptional biotas allow new approaches. Models for diversity regulation through time range from the entirely biotic to the entirely physical, with many intermediates. Tetrapod diversity has risen as a result of the expansion of ecospace, rather than niche subdivision or regional-scale endemicity resulting from continental break-up. Tetrapod communities on land have been remarkably stable and have changed only when there was a revolution in floras (such as the demise of the Carboniferous coal forests, or the Cretaceous radiation of angiosperms) or following particularly severe mass extinction events, such as that at the end of the Permian.

scholarly journals To be or not to be: the early history of H 3 and H 3 +

2012 ◽  
Vol 370 (1978) ◽  
pp. 5225-5235 ◽  
Author(s):  
Helge Kragh
Keyword(s):  
Quantum Chemistry ◽  
Research Area ◽  
Early History ◽  
Active Hydrogen ◽  
Major Research ◽  
New Methods ◽  
History Of

Triatomic hydrogen became a major research area only after 1980, but its history goes back to J. J. Thomson’s discovery in 1911. In fact, the possible existence of H 3 was suggested as early as 1895. This paper outlines the history of H 3 and up to the mid-1930s, when chemists and physicists ceased to believe in the existence of the H 3 molecule. In the intervening years, there was a great deal of interest in ‘active hydrogen’ and also in the configuration of H 3 , which was examined by Bohr in 1919. While H 3 was abandoned, was not. Although the properties of were largely unknown, the existence of the ion was firmly established, and its structure studied by means of the new methods of quantum chemistry.

scholarly journals Fundamental molecules of life are pigments which arose and evolved to dissipate the solar spectrum

2015 ◽  
Vol 12 (3) ◽  
pp. 2101-2160 ◽  
Author(s):  
K. Michaelian ◽  
A. Simeonov
Keyword(s):  
Cross Sections ◽  
Dissipation Rate ◽  
Solar Spectrum ◽  
Photochemical Process ◽  
Physical Size ◽  
Origin And Evolution ◽  
Organic Pigments ◽  
Early Atmosphere ◽  
Evolution Of Life ◽  
History Of

Abstract. The driving force behind the origin and evolution of life has been the thermodynamic imperative of increasing the entropy production of the biosphere through increasing the global solar photon dissipation rate. In the upper atmosphere of today, oxygen and ozone derived from life processes are performing the short wavelength UVC and UVB dissipation. On Earth's surface, water and organic pigments in water facilitate the near UV and visible photon dissipation. The first organic pigments probably formed, absorbed, and dissipated at those photochemically active wavelengths in the UVC that could have reached Earth's surface during the Archean. Proliferation of these pigments can be understood as an autocatalytic photochemical process obeying non-equilibrium thermodynamic directives related to increasing solar photon dissipation rate. Under these directives, organic pigments would have evolved over time to increase the global photon dissipation rate by; (1) increasing the ratio of their effective photon cross sections to their physical size, (2) decreasing their electronic excited state life times, (3) quenching radiative de-excitation channels (e.g. fluorescence), (4) covering ever more completely the prevailing solar spectrum, and (5) proliferating and dispersing to cover an ever greater surface area of Earth. From knowledge of the evolution of the spectrum of G-type stars, and considering the most probable history of the transparency of Earth's atmosphere, we construct the most probable Earth surface solar spectrum as a function of time and compare this with the history of molecular absorption maxima obtained from the available data in the literature. This comparison supports the conjecture that many fundamental molecules of life are pigments which arose and evolved to dissipate the solar spectrum, supports the thermodynamic dissipation theory for the origin of life, constrains models for Earth's early atmosphere, and sheds some new light on the origin of photosynthesis.

scholarly journals Fundamental molecules of life are pigments which arose and co-evolved as a response to the thermodynamic imperative of dissipating the prevailing solar spectrum

2015 ◽  
Vol 12 (16) ◽  
pp. 4913-4937 ◽  
Author(s):  
K. Michaelian ◽  
A. Simeonov
Keyword(s):  
Cross Sections ◽  
Dissipation Rate ◽  
Solar Spectrum ◽  
Photochemical Process ◽  
Origin And Evolution ◽  
Organic Pigments ◽  
Early Atmosphere ◽  
Evolution Of Life ◽  
History Of ◽  
Uv C

Abstract. The driving force behind the origin and evolution of life has been the thermodynamic imperative of increasing the entropy production of the biosphere through increasing the global solar photon dissipation rate. In the upper atmosphere of today, oxygen and ozone derived from life processes are performing the short-wavelength UV-C and UV-B dissipation. On Earth's surface, water and organic pigments in water facilitate the near-UV and visible photon dissipation. The first organic pigments probably formed, absorbed, and dissipated at those photochemically active wavelengths in the UV-C and UV-B that could have reached Earth's surface during the Archean. Proliferation of these pigments can be understood as an autocatalytic photochemical process obeying non-equilibrium thermodynamic directives related to increasing solar photon dissipation rate. Under these directives, organic pigments would have evolved over time to increase the global photon dissipation rate by (1) increasing the ratio of their effective photon cross sections to their physical size, (2) decreasing their electronic excited state lifetimes, (3) quenching radiative de-excitation channels (e.g., fluorescence), (4) covering ever more completely the prevailing solar spectrum, and (5) proliferating and dispersing to cover an ever greater surface area of Earth. From knowledge of the evolution of the spectrum of G-type stars, and considering the most probable history of the transparency of Earth's atmosphere, we construct the most probable Earth surface solar spectrum as a function of time and compare this with the history of molecular absorption maxima obtained from the available data in the literature. This comparison supports the conjecture that many fundamental molecules of life are pigments which arose, proliferated, and co-evolved as a response to dissipating the solar spectrum, supports the thermodynamic dissipation theory for the origin of life, constrains models for Earth's early atmosphere, and sheds some new light on the origin of photosynthesis.

scholarly journals Concurrent origins of the genetic code and the homochirality of life, and the origin and evolution of biodiversity. Part II: Technical appendix

2015 ◽  
Author(s):  
Dirson Jian Li
Keyword(s):  
Genetic Code ◽  
Origin And Evolution ◽  
Technical Details

Here is Part II of my two-part series paper, which provides technical details and evidence for Part I of this paper (see “Concurrent origins of the genetic code and the homochirality of life, and the origin and evolution of biodiversity. Part I: Observations and explanations” on bioRxiv).

Evolution Before Darwin

2019 ◽  
Author(s):  
Bill Jenkins
Keyword(s):  
Natural History ◽  
Charles Darwin ◽  
Natural World ◽  
Origin And Evolution ◽  
Evolutionary Theories ◽  
Evolutionary Thought ◽  
Evolution Of Life ◽  
History Of ◽  
New Ideas ◽  
The City

It was long believed that evolutionary theories received an almost universally cold reception in British natural history circles in the first half of the nineteenth century. But recently serious doubt has been cast on this assumption. This book will be the first major study of what was the most important centre or pre-Darwinian evolutionary thought in the British Isles. It shows that Edinburgh in the late 1820s and early 1830s was witness to a veritable ferment of radical new ideas on the natural world, including speculation on the origin and evolution of life, at just the time when Charles Darwin was studying medicine in the city. Those who were students in Edinburgh at the time could have hardly avoided coming into contact with these new ideas, espoused as they were by many of professors, fellow students and acquaintances in Edinburgh. This book sheds new light on the genesis and development of one of the most important scientific theories in the history of western thought.

Some early history of replica techniques for electron microscopy

1992 ◽  
Vol 50 (2) ◽  
pp. 1076-1077
Author(s):  
Robert M. Fisher
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Optical Microscope ◽  
Early History ◽  
Bulk Materials ◽  
Thin Sections ◽  
Transmission Electron ◽  
Reflected Light ◽  
History Of ◽  
Electron Microscopes

By 1940, a half dozen or so commercial or home-built transmission electron microscopes were in use for studies of the ultrastructure of matter. These operated at 30-60 kV and most pioneering microscopists were preoccupied with their search for electron transparent substrates to support dispersions of particulates or bacteria for TEM examination and did not contemplate studies of bulk materials. Metallurgist H. Mahl and other physical scientists, accustomed to examining etched, deformed or machined specimens by reflected light in the optical microscope, were also highly motivated to capitalize on the superior resolution of the electron microscope. Mahl originated several methods of preparing thin oxide or lacquer impressions of surfaces that were transparent in his 50 kV TEM. The utility of replication was recognized immediately and many variations on the theme, including two-step negative-positive replicas, soon appeared. Intense development of replica techniques slowed after 1955 but important advances still occur. The availability of 100 kV instruments, advent of thin film methods for metals and ceramics and microtoming of thin sections for biological specimens largely eliminated any need to resort to replicas.

The early history of tuberous sclerosis

1979 ◽  
Vol 115 (11) ◽  
pp. 1317-1319 ◽  
Author(s):  
J. E. Morgan
Keyword(s):  
Tuberous Sclerosis ◽  
Early History ◽  
History Of

New Light on the Early History of the Greater Northwest

2015 ◽  
Author(s):  
Alexander Henry ◽  
David Thompson
Keyword(s):  
Early History ◽  
History Of
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