scholarly journals Carbonate biomineralization differentially induced by two psychrophilic Pseudomonas psychrophila strains isolated from an alpine travertine landform

RSC Advances ◽  
2021 ◽  
Vol 11 (21) ◽  
pp. 12885-12892
Author(s):  
Na Song ◽  
Qiongfang Li ◽  
Yi Zhou ◽  
Geng Sun ◽  
Ling Pan ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Organic Compounds ◽  
Psychrophilic Pseudomonas

Calcium carbonate crystals induced by two Pseudomonas psychrophila strains and their organic compounds were studied.

Soil receptivity for ectomycorrhizal fungi: Tuber aestivum is specifically stimulated by calcium carbonate and certain organic compounds, but not mycorrhizospheric bacteria

2017 ◽  
Vol 117-118 ◽  
pp. 38-45 ◽  
Author(s):  
Milan Gryndler ◽  
Olena Beskid ◽  
Martina Hujslová ◽  
Tereza Konvalinková ◽  
Petra Bukovská ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Organic Compounds ◽  
Ectomycorrhizal Fungi ◽  
Tuber Aestivum

Shielding biomolecules from effects of radiation by Mars analogue minerals and soils

2016 ◽  
Vol 16 (3) ◽  
pp. 280-285 ◽  
Author(s):  
G. Ertem ◽  
M. C. Ertem ◽  
C. P. McKay ◽  
R. M. Hazen
Keyword(s):  
Calcium Carbonate ◽  
Organic Compounds ◽  
Uv Radiation ◽  
European Space Agency ◽  
Calcium Sulphate ◽  
Interplanetary Dust ◽  
Dust Particles ◽  
Martian Surface ◽  
Interplanetary Dust Particles ◽  
Uv Photolysis

AbstractOrganic compounds have been delivered over time to Mars via meteorites, comets and interplanetary dust particles. The fate of organic material on the surface of Mars must be affected by the Martian environment, in particular by ultraviolet (UV) and other ionizing radiation. Penetration depth of UV radiation into soils is in the sub-millimetre to millimetre range and depends on the properties of the soil. The aim of this research is to study the possible protective role of Martian analogue minerals and soils for survivability of biomolecules against UV radiation and to compare their decomposition rates within a 1 mm-thick portion of the surface. Results demonstrated that minerals offer significant protection to biomolecules purine, pyrimidine and uracil against UV photolysis. In the absence of these minerals, organic compounds are completely degraded when subjected directly to UV photolysis equivalent to only 5 Martian day's exposure. However, similar UV exposure of organics dried from solution onto powdered calcium carbonate (calcite; CaCO3), calcium sulphate (anhydrite; CaSO4), clay-bearing Atacama dessert soil and 7 Å clay mineral kaolinite [Al2Si2O5(OH)4] results in only 1–2% loss of organics. Mixtures of purine and uracil with calcium carbonate exposed to gamma radiation of 3 Gy (3 Gray), which corresponds to approximately 15 000 days on Mars, results in up to 10% loss of organics. By contrast, these organic compounds completely decomposed upon mixing with iron oxide (Fe2O3) before UV irradiation. As the search for extinct or extant life on Mars has been identified as a goal of top priority in NASA's Mars Exploration Program and continues with several missions planned to the red planet by both NASA and the European Space Agency (ESA) in the next few decades, our findings may play a useful role in identifying optimal target sites on the Martian surface for future missions.

The Tempo and mode(S) of Prebiotic Evolution

1997 ◽  
Vol 161 ◽  
pp. 419-429 ◽  
Author(s):  
Antonio Lazcano
Keyword(s):  
Origin Of Life ◽  
Organic Compounds ◽  
Biological Evolution ◽  
Current Evidence ◽  
Early Diversification ◽  
Time Period ◽  
The Galaxy ◽  
History Of ◽  
Widespread Phenomenon ◽  
The Origin Of Life

AbstractDifferent current ideas on the origin of life are critically examined. Comparison of the now fashionable FeS/H2S pyrite-based autotrophic theory of the origin of life with the heterotrophic viewpoint suggest that the later is still the most fertile explanation for the emergence of life. However, the theory of chemical evolution and heterotrophic origins of life requires major updating, which should include the abandonment of the idea that the appearance of life was a slow process involving billions of years. Stability of organic compounds and the genetics of bacteria suggest that the origin and early diversification of life took place in a time period of the order of 10 million years. Current evidence suggest that the abiotic synthesis of organic compounds may be a widespread phenomenon in the Galaxy and may have a deterministic nature. However, the history of the biosphere does not exhibits any obvious trend towards greater complexity or «higher» forms of life. Therefore, the role of contingency in biological evolution should not be understimated in the discussions of the possibilities of life in the Universe.

A TEM study of the microstructure of avian eggshells

1992 ◽  
Vol 50 (2) ◽  
pp. 1102-1103
Author(s):  
S. Q. Xiao ◽  
S. Baden ◽  
A. H. Heuer
Keyword(s):  
Electron Microscope ◽  
Calcium Carbonate ◽  
Nucleation And Growth ◽  
Growth Mechanisms ◽  
Shell Surface ◽  
Thin Sections ◽  
Polycrystalline Metals ◽  
Transmission Electron ◽  
Nucleation And Growth Mechanisms

The avian eggshell is one of the most rapidly mineralizing biological systems known. In situ, 5g of calcium carbonate are crystallized in less than 20 hrs to fabricate the shell. Although there have been much work about the formation of eggshells, controversy about the nucleation and growth mechanisms of the calcite crystals, and their texture in the eggshell, still remain unclear. In this report the microstructure and microchemistry of avian eggshells have been analyzed using transmission electron microscope (TEM) and energy dispersive spectroscopy (EDS).Fresh white and dry brown eggshells were broken and fixed in Karnosky's fixative (kaltitanden) for 2 hrs, then rinsed in distilled H2O. Small speckles of the eggshells were embedded in Spurr medium and thin sections were made ultramicrotome.The crystalline part of eggshells are composed of many small plate-like calcite grains, whose plate normals are approximately parallel to the shell surface. The sizes of the grains are about 0.3×0.3×1 μm3 (Fig.l). These grains are not as closely packed as man-made polycrystalline metals and ceramics, and small gaps between adjacent grains are visible indicating the absence of conventional grain boundaries.

Sign in / Sign up

Export Citation Format

Share Document