scholarly journals Ammonia oxidation at pH 2.5 by a new gammaproteobacterial ammonia-oxidizing bacterium

2020 ◽  
Author(s):  
Nunzia Picone ◽  
Arjan Pol ◽  
Rob Mesman ◽  
Maartje A. H. J. van Kessel ◽  
Geert Cremers ◽  
...  
Keyword(s):  
Growth Rate ◽  
Doubling Time ◽  
Ammonia Oxidation ◽  
Microscopic Analysis ◽  
Ammonia Oxidizers ◽  
Electron Microscopic ◽  
Intracytoplasmic Membrane ◽  
Nitrogenous Compounds ◽  
Continuous Bioreactor ◽  
Ammonia Oxidizing Bacterium

AbstractAmmonia oxidation was considered impossible under highly acidic conditions, as the protonation of ammonia leads to decreased substrate availability and formation of toxic nitrogenous compounds. Recently, some studies described archaeal and bacterial ammonia oxidizers growing at pH as low as 4, while environmental studies observed nitrification at even lower pH values. In this work, we report on the discovery, cultivation, and physiological, genomic, and transcriptomic characterization of a novel gammaproteobacterial ammonia-oxidizing bacterium enriched via continuous bioreactor cultivation from an acidic air biofilter that was able to grow and oxidize ammonia at pH 2.5. This microorganism has a chemolithoautotrophic lifestyle, using ammonia as energy source. The observed growth rate on ammonia was 0.196 day−1, with a doubling time of 3.5 days. The strain also displayed ureolytic activity and cultivation with urea as ammonia source resulted in a growth rate of 0.104 day−1 and a doubling time of 6.7 days. A high ammonia affinity (Km(app) = 147 ± 14 nM) and high tolerance to toxic nitric oxide could represent an adaptation to acidic environments. Electron microscopic analysis showed coccoid cell morphology with a large amount of intracytoplasmic membrane stacks, typical of gammaproteobacterial ammonia oxidizers. Furthermore, genome and transcriptome analysis showed the presence and expression of diagnostic genes for nitrifiers (amoCAB, hao, nor, ure, cbbLS), but no nirK was identified. Phylogenetic analysis revealed that this strain belonged to a novel bacterial genus, for which we propose the name “Candidatus Nitrosacidococcus tergens” sp. RJ19.

Preparatory Procedures for Electron Microscopic Analysis at the Molecular Level of Resolution

1978 ◽  
Vol 36 (3) ◽  
pp. 516-520
Author(s):  
F.J. Sjostrand
Keyword(s):  
Electron Microscope ◽  
Molecular Level ◽  
Microscopic Analysis ◽  
Resolving Power ◽  
Cellular Structures ◽  
Electron Microscopic ◽  
Systematic Analysis ◽  
Technical Developments ◽  
Thin Sectioning ◽  
Obvious Reason

In the 1940's and 1950's electron microscopy conferences were attended with everybody interested in learning about the latest technical developments for one very obvious reason. There was the electron microscope with its outstanding performance but nobody could make very much use of it because we were lacking proper techniques to prepare biological specimens. The development of the thin sectioning technique with its perfectioning in 1952 changed the situation and systematic analysis of the structure of cells could now be pursued. Since then electron microscopists have in general become satisfied with the level of resolution at which cellular structures can be analyzed when applying this technique. There has been little interest in trying to push the limit of resolution closer to that determined by the resolving power of the electron microscope.

Electron Microscopic Analysis of Myonecrosis Induced by a Pure Component Isolated From Rattlesnake Venom

1976 ◽  
Vol 34 ◽  
pp. 292-293
Author(s):  
Charlotte L. Ownby ◽  
David Cameron ◽  
Anthony T. Tu
Keyword(s):  
Gel Filtration ◽  
Microscopic Analysis ◽  
The United States ◽  
Exchange Chromatography ◽  
Pure Component ◽  
Electron Microscopic Level ◽  
Electron Microscopic ◽  
Mouse Muscle ◽  
Major Health Problem ◽  
Rattlesnake Venom

In the United States the major health problem resulting from snakebite poisoning is local tissue damage, i.e. hemorrhage and myonecrosis. Since commercial antivenin does not usually prevent such damage to tissue, a more effective treatment of snakebite-induced myonecrosis is needed. To aid in the development of such a treatment the pathogenesis of myonecrosis induced by a pure component of rattlesnake venom was studied at the electron microscopic level.The pure component, a small (4,300 mol. wt.), basic (isoelectric point of 9.6) protein, was isolated from crude prairie rattlesnake (Crotalus viridis viridis) venom by gel filtration (Sephadex G-50) followed by cation exchange chromatography (Sephadex C-25), and shown to be pure by electrophoresis. Selection of the myotoxic component was based on light microscopic observations of injected mouse muscle.

Correlative video enhanced differential interference contrast light microscopy (VDIC)-LM), low-voltage high-resolution SEM (LV-HR-SEM), and high-voltage electron microscopy (HVEM) in the observation of gold-labelled surface antigens and the subjacent cytoskeletal matrix

1989 ◽  
Vol 47 ◽  
pp. 904-905
Author(s):  
Ralph M. Albrecht ◽  
Scott R. Simmons ◽  
Marek Malecki
Keyword(s):  
High Resolution ◽  
Light Microscopy ◽  
Low Voltage ◽  
Microscopic Analysis ◽  
Cell Labelling ◽  
Video Technology ◽  
Electron Microscopic ◽  
Image Capture ◽  
High Voltage Electron Microscopy ◽  
Fluorescence Studies

The development of video-enhanced light microscopy (LM) as well as associated image processing and analysis have significantly broadened the scope of investigations which can be undertaken using (LM). Interference/polarization based microscopies can provide high resolution and higher levels of “detectability” especially in unstained living systems. Confocal light microscopy also holds the promise of further improvements in resolution, fluorescence studies, and 3 dimensional reconstruction. Video technology now provides, among other things, a means to detect differences in contrast difficult to detect with the human eye; furthermore, computerized image capture, processing, and analysis can be used to enhance features of interest, average images, subtract background, and provide a quantitative basis to studies of cells, cell features, cell labelling, and so forth. Improvements in video technology, image capture, and cost-effective computer image analysis/processing have contributed to the utility and potential of the various interference and confocal microscopic instrumentation.Electron microscopic technology has made advances as well. Microprocessor control and improved design have contributed to high resolution SEMs which have imaging capability at the molecular level and can operate at a range of accelerating voltages starting at 1KV. Improvements have also been seen in the HVEM and IVEM transmission instruments. As a whole, these advances in LM and EM microscopic technology provide the biologist with an array of information on structure, composition, and function which can be obtained from a single specimen. Corrrelative light microscopic analysis permits examination of living specimens and is critical where the “history” of a cell, cellular components, or labels needs to be known up to the time of chemical or physical fixation. Features such as cytoskeletal elements or gold label as small as 0.01 μm, well below the 0.2 μm limits of LM resolution, can be “detected” and their movement followed by VDIC-LM. Appropriate identification and preparation can then lead to the examination of surface detail and surface label with stereo LV-HR-SEM. Increasing the KV in the HR-SEM while viewing uncoated or thinly coated specimens can provide information from beneath the surface as well as increasing Z contrast so that positive identification of surface and subsurface colloidal gold or other heavy metal labelled/stained material is possible. Further examination of the same cells using stereo HVEM or IVEM provides information on internal ultrastructure and on the relationship of labelled material to cytoskeletal or organellar distribution, A wide variety of investigations can benefit from this correlative approach and a number of instrumentational configurations and preparative pathways can be tailored for the particular study. For a surprisingly small investment in time and technique, it is often possible to clear ambiguities or questions that arise when a finding is presented in the context of only one modality.

scholarly journals Mechanistic Study on Gold-Like Luster Development of Solution-Cast Oligo(3-methoxythiophene) Film

Coatings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 861
Author(s):  
Minako Kubo ◽  
Minako Tachiki ◽  
Terumasa Mitogawa ◽  
Kota Saito ◽  
Ryota Saito ◽  
...  
Keyword(s):  
Microscopic Analysis ◽  
Mechanistic Study ◽  
Free Electrons ◽  
Coating Films ◽  
Electron Microscopic ◽  
Regular Structures ◽  
Scanning Electron Microscopic ◽  
Solution Cast ◽  
Scanning Electron Microscopic Analysis ◽  
Reflectance Measurements

Solution-cast coating films of perchlorate-doped oligo(3-methoxythiophene) exhibited a gold-like luster similar to that of metallic gold despite the involvement of no metals. However, the development mechanism of the luster remains ambiguous. To understand the mechanism, we performed scanning electron microscopic analysis, variable-angle spectral reflectance measurements, and ellipsometry measurements on ClO4−-doped oligo(3-methoxythiophene) cast film with a gold-like luster. The results revealed that the lustrous color of the film was not induced by the submicron-sized regular structures (structural color), nor by the high-density free electrons (reflective response based on Drude model), but by the large optical constants (refractive index and extinction coefficient) of the film, as speculated previously.

scholarly journals Straw mulching and nitrogen application altered ammonia oxidizers communities and improved soil quality in the alkaline purple soil of southwest China

AMB Express ◽  
2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Songhe Chen ◽  
Rencai Gao ◽  
Xiaoling Xiang ◽  
Hongkun Yang ◽  
Hongliang Ma ◽  
...  
Keyword(s):  
Soil Quality ◽  
Ammonia Oxidation ◽  
Management Strategies ◽  
Rflp Analysis ◽  
Available Phosphorus ◽  
Purple Soil ◽  
Ammonia Oxidizers ◽  
Nitrogen Application ◽  
Available Nitrogen ◽  
Straw Mulching

AbstractMicrobe-mediated ammonia oxidation is a key process in soil nitrogen cycle. However, the effect of maize straw mulching on the ammonia oxidizers in the alkaline purple soil remains largely unknown. A three-year positioning experiment was designed as follows: straw mulching measures as the main-plot treatment and three kinds of nitrogen application as the sub-plot treatment. We found the contents of soil organic carbon (SOC), total nitrogen (TN), available potassium (AK), available nitrogen (AN), available phosphorus (AP), and NH4+-N were increased after straw mulching and nitrogen application in alkaline purple soil, so did the amoA genes abundance of ammonia-oxidizing archaeal (AOA) and bacterial (AOB). Terminal restriction fragment length polymorphism (T-RFLP) analysis revealed that Thaumarchaeote (448-bp T-RF) was dominated the AOA communities, whereas Nitrosospira sp (111-bp T-RF) dominated the AOB communities. The community compositions of both AOA and AOB were altered by straw mulching and nitrogen application in alkaline purple soil, however, the AOB communities was more responsive than AOA communities to the straw mulching and nitrogen application. Further analysis indicated that SOC and AP were the main factors affecting the abundance and community compositions of AOA and AOB in alkaline purple soil. The present study reported that straw mulching and nitrogen strategies differently shape the soil ammonia oxidizers community structure and abundance, which should be considered when evaluating agricultural management strategies regarding their sustainability and soil quality.

A Bibliometric Analysis of the Top 100 Cited Papers in Retinal Detachment

2021 ◽  
pp. 247412642110073
Author(s):  
Masumi George Asahi ◽  
Haig Pakhchanian ◽  
Christine Doepker ◽  
Rahul Raiker ◽  
Ron P. Gallemore
Keyword(s):  
Retinal Detachment ◽  
Bibliometric Analysis ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Microscopic Analysis ◽  
The United States ◽  
Electron Microscopic ◽  
Research Areas ◽  
Science Index ◽  
Funding Agencies

Purpose: This work aimed to identify and analyze the most frequently cited articles in retinal detachment (RD). Methods: Institute for Scientific Information’s Web of Science index (Thomas Scientific) was used to identify the top 100 most cited articles on RD between 1900 and 2019. Data from the top 100 most cited articles that met inclusion criteria were analyzed based on title, citation frequency, authorship, institution, journal, year of publication, and country of origin. Results: The top 100 articles in RD were cited 88 to 480 times. Steven K. Fisher was the most cited individual, with the University of California system being the most cited organization. Sixty-four percent of the top 100 articles originated from the United States and were published in the American Journal of Ophthalmology, Ophthalmology, and Archives of Ophthalmology at frequencies of 36%, 24%, and 11%, respectively. The top funding agencies included the US Department of Health and Human Services, the National Institutes of Health, and the National Eye Institute at 29%, 28%, and 27%, respectively. The top-cited article, which assessed the role of the retinal pigment epithelium by histologic and electron microscopic analysis of RDs in eyes of owl monkeys, was by Machemer and Laqua in the American Journal of Ophthalmology. Conclusions: This bibliometric analysis provides researchers and clinicians with a detailed overview of the most cited manuscripts in RD. Such analyses may guide researchers and funding agencies on important research areas in the field.

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