Impact of Different In Vitro Electron Donor/Acceptor Conditions on Potential Chemolithoautotrophic Communities from Marine Pelagic Redoxclines

ABSTRACT Anaerobic or microaerophilic chemolithoautotrophic bacteria have been considered to be responsible for CO2 dark fixation in different pelagic redoxclines worldwide, but their involvement in redox processes is still not fully resolved. We investigated the impact of 17 different electron donor/acceptor combinations in water of pelagic redoxclines from the central Baltic Sea on the stimulation of bacterial CO2 dark fixation as well as on the development of chemolithoautotrophic populations. In situ, the highest CO2 dark fixation rates, ranging from 0.7 to 1.4 μmol liter−1 day−1, were measured directly below the redoxcline. In enrichment experiments, chemolithoautotrophic CO2 dark fixation was maximally stimulated by the addition of thiosulfate, reaching values of up to 9.7 μmol liter−1 CO2 day−1. Chemolithoautotrophic nitrate reduction proved to be an important process, with rates of up to 33.5 μmol liter−1 NO3 − day−1. Reduction of Fe(III) or Mn(IV) was not detected; nevertheless, the presence of these potential electron acceptors influenced the development of stimulated microbial assemblages. Potential chemolithoautotrophic bacteria in the enrichment experiments were displayed on 16S ribosomal complementary DNA single-strand-conformation polymorphism fingerprints and identified by sequencing of excised bands. Sequences were closely related to chemolithoautotrophic Thiomicrospira psychrophila and Maorithyas hadalis gill symbiont (both Gammaproteobacteria) and to an uncultured nitrate-reducing Helicobacteraceae bacterium (Epsilonproteobacteria). Our data indicate that this Helicobacteraceae bacterium could be of general importance or even a key organism for autotrophic nitrate reduction in pelagic redoxclines.

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Dysregulated interactions triggered by a neuropathy-causing mutation in the IPV motif of HSP27

10.1101/708180 ◽

2019 ◽

Cited By ~ 1

Author(s):

T. Reid Alderson ◽

Elias Adriaenssens ◽

Bob Asselbergh ◽

Iva Pritišanac ◽

Heidi Y. Gastall ◽

...

Keyword(s):

Small Heat Shock Protein ◽

Severe Form ◽

Protein Protein Interaction ◽

Charcot Marie Tooth Disease ◽

System A ◽

General Importance ◽

Mechanistic Basis ◽

The Impact

HSP27 (HSPB1) is a systemically expressed human small heat-shock protein that forms large, dynamic oligomers and functions in various aspects of cellular homeostasis. Mutations in HSP27 cause Charcot-Marie-Tooth disease, the most common inherited disorder of the peripheral nervous system. A particularly severe form of the disease is triggered by the P182L mutation within the highly conserved IxI/V motif of HSP27. Here, we observed that the P182L variant of HSP27 lacks the ability to prevent the aggregation of client proteins and formed significantly larger oligomers both in vitro and in vivo. NMR spectroscopy revealed that the P182L IxI/V motif binds its α-crystallin domain with significantly lower association rate, and thus affinity, rendering the binding site more available for other interactors. We identified 22 IxI/V-containing proteins that are known to interact with HSP27 and could therefore bind with enhanced affinity to the P182L variant. We validated this hypothesis through co-immunoprecipitation experiments, revealing that the IxI/V motif-bearing co-chaperone BAG3 indeed binds with higher affinity to the P182L variant. Our results provide a mechanistic basis for the impact of the P182L mutation on HSP27, and highlight the general importance of the IxI/V motif and its role in protein-protein interaction networks.

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Nitrate removal by a novel lithoautotrophic nitrate-reducing iron(II)-oxidizing culture enriched from a pyrite-rich limestone aquifer

Applied and Environmental Microbiology ◽

10.1128/aem.00460-21 ◽

2021 ◽

Author(s):

Natalia Jakus ◽

Nia Blackwell ◽

Karsten Osenbrück ◽

Daniel Straub ◽

James M. Byrne ◽

...

Keyword(s):

Microbial Community ◽

Organic Carbon ◽

Electron Donor ◽

Nitrate Reduction ◽

Nitrate Removal ◽

Electron Donors ◽

Rrna Gene ◽

Organic Substrates ◽

Limestone Aquifer ◽

Chemolithoautotrophic Bacteria

Nitrate removal in oligotrophic environments is often limited by the availability of suitable organic electron donors. Chemolithoautotrophic bacteria may play a key role in denitrification in aquifers depleted in organic carbon. Under anoxic and circumneutral pH conditions, iron(II) was hypothesized to serve as an electron donor for microbially mediated nitrate reduction by Fe(II)-oxidizing (NRFeOx) microorganisms. However, lithoautotrophic NRFeOx cultures have never been enriched from any aquifer and as such there are no model cultures available to study the physiology and geochemistry of this potentially environmentally relevant process. Using iron(II) as an electron donor, we enriched a lithoautotrophic NRFeOx culture from nitrate-containing groundwater of a pyrite-rich limestone aquifer. In the enriched NRFeOx culture that does not require additional organic co-substrates for growth, within 7-11 days 0.3-0.5 mM of nitrate was reduced and 1.3-2 mM of iron(II) was oxidized leading to a stoichiometric NO 3 - /Fe(II) ratio of 0.2, with N 2 and N 2 O identified as the main nitrate reduction products. Short-range ordered Fe(III) (oxyhydr)oxides were the product of iron(II) oxidation. Microorganisms were observed to be closely associated with formed minerals but only few cells were encrusted, suggesting that most of the bacteria were able to avoid mineral precipitation at their surface. Analysis of the microbial community by long-read 16S rRNA gene sequencing revealed that the culture is dominated by members of the Gallionellaceae family that are known as autotrophic, neutrophilic, microaerophilic iron(II)-oxidizers. In summary, our study suggests that NRFeOx mediated by lithoautotrophic bacteria can lead to nitrate removal in anthropogenically impacted aquifers. Importance Removal of nitrate by microbial denitrification in groundwater is often limited by low concentrations of organic carbon. In these carbon-poor ecosystems, nitrate-reducing bacteria that can use inorganic compounds such as Fe(II) (NRFeOx) as electron donors could play a major role in nitrate removal. However, no lithoautotrophic NRFeOx culture has been successfully isolated or enriched from this type of environment and as such there are no model cultures available to study the rate-limiting factors of this potentially important process. Here we present the physiology and microbial community composition of a novel lithoautotrophic NRFeOx culture enriched from a fractured aquifer in southern Germany. The culture is dominated by a putative Fe(II)-oxidizer affiliated with the Gallionellaceae family and performs nitrate reduction coupled to Fe(II) oxidation leading to N 2 O and N 2 formation without the addition of organic substrates. Our analyses demonstrate that lithoautotrophic NRFeOx can potentially lead to nitrate removal in nitrate-contaminated aquifers.

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Evaluation of the Impact of Excipients on Albendazole Concentrations in Upper Small Intestine Using an In Vitro Biorelevant Gastrointestinal Transfer (BioGIT) System

10.26226/morressier.57d6b2bbd462b8028d88e13f ◽

2016 ◽

Author(s):

Maria Vertzoni

Keyword(s):

Small Intestine ◽

The Impact

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Metal-Free Photoinduced Hydroalkylation Cascade Enabled by an Electron-Donor-Acceptor Complex

10.26434/chemrxiv.11912073 ◽

2020 ◽

Author(s):

José Tiago Menezes Correia ◽

Gustavo Piva da Silva ◽

Camila Menezes Kisukuri ◽

Elias André ◽

Bruno Pires ◽

...

Keyword(s):

Electron Donor ◽

Functional Group ◽

Photoexcited Electron ◽

One Pot ◽

Quaternary Centers ◽

Metal Free ◽

Acceptor Complex ◽

Catalyst Free ◽

Donor Acceptor ◽

Radical Cascade

A metal- and catalyst-free photoinduced radical cascade hydroalkylation of 1,7-enynes has been disclosed. The process is triggered by a SET event involving a photoexcited electron-donor-aceptor complex between NHPI ester and Hantzsch ester, which decomposes to afford a tertiary radical that is readily trapped by the enyne. <a>The method provides an operationally simple, robust and step-economical approach to the construction of diversely functionalized dihydroquinolinones bearing quaternary-centers. A sequential one-pot hydroalkylation-isomerization approach is also allowed giving access to a family of quinolinones. A wide substrate scope and high functional group tolerance was observed in both approaches</a>.

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The Predominant microRNAs in β-cell Clusters for Insulin Regulation and Diabetic Control

Current Drug Targets ◽

10.2174/1389450121666191230145848 ◽

2020 ◽

Vol 21 (7) ◽

pp. 722-734

Author(s):

Adele Soltani ◽

Arefeh Jafarian ◽

Abdolamir Allameh

Keyword(s):

Mirna Expression ◽

Expression Profiles ◽

Expression Patterns ◽

Diabetic Control ◽

In Vitro Proliferation ◽

Cell Functions ◽

Mirna Expression Profiles ◽

Multiple Processes ◽

The Impact

micro (mi)-RNAs are vital regulators of multiple processes including insulin signaling pathways and glucose metabolism. Pancreatic β-cells function is dependent on some miRNAs and their target mRNA, which together form a complex regulative network. Several miRNAs are known to be directly involved in β-cells functions such as insulin expression and secretion. These small RNAs may also play significant roles in the fate of β-cells such as proliferation, differentiation, survival and apoptosis. Among the miRNAs, miR-7, miR-9, miR-375, miR-130 and miR-124 are of particular interest due to being highly expressed in these cells. Under diabetic conditions, although no specific miRNA profile has been noticed, the expression of some miRNAs and their target mRNAs are altered by posttranscriptional mechanisms, exerting diverse signs in the pathobiology of various diabetic complications. The aim of this review article is to discuss miRNAs involved in the process of stem cells differentiation into β-cells, resulting in enhanced β-cell functions with respect to diabetic disorders. This paper will also look into the impact of miRNA expression patterns on in vitro proliferation and differentiation of β-cells. The efficacy of the computational genomics and biochemical analysis to link the changes in miRNA expression profiles of stem cell-derived β-cells to therapeutically relevant outputs will be discussed as well.

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The Impact of Antioxidants from the Diet on Breast Cancer Cells Monitored by Raman Microspectroscopy

Letters in Drug Design & Discovery ◽

10.2174/1570180815666180502120804 ◽

2018 ◽

Vol 16 (2) ◽

pp. 127-137

Author(s):

Paula Sofia Coutinho Medeiros ◽

Ana Lúcia Marques Batista de Carvalho ◽

Cristina Ruano ◽

Juan Carlos Otero ◽

Maria Paula Matos Marques

Keyword(s):

Breast Cancer ◽

Cancer Cells ◽

Cell Line ◽

Breast Cancer Cells ◽

Triple Negative ◽

Breast Adenocarcinoma ◽

Coumaric Acid ◽

Human Breast ◽

The Impact

Background: The impact of the ubiquitous dietary phenolic compound p-coumaric acid on human breast cancer cells was assessed, through a multidisciplinary approach: Combined biological assays for cytotoxicity evaluation and biochemical profiling by Raman microspectroscopic analysis in cells. </P><P> Methods: Para-coumaric acid was shown to exert in vitro chemoprotective and antitumor activities, depending on the concentration and cell line probed: a significant anti-invasive ability was detected for the triple-negative MDA-MB-231 cells, while a high pro-oxidant effect was found for the estrogen- dependent MCF-7 cells. A striking cell selectivity was obtained, with a more noticeable outcome on the triple-negative MDA-MB-231 cell line. Results: The main impact on the cellular biochemical profile was verified to be on proteins and lipids, thus justifying the compound´s anti-invasive effect and chemoprotective ability. Conclusion: p-Coumaric acid was thus shown to be a promising chemoprotective/chemotherapeutic agent, particularly against the low prognosis triple-negative human breast adenocarcinoma.

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VDAC1 Mediated Anticancer Activity of Gallic Acid in Human Lung Adenocarcinoma A549 Cells

Anti-Cancer Agents in Medicinal Chemistry ◽

10.2174/1871520617666170912115441 ◽

2018 ◽

Vol 18 (2) ◽

pp. 255-262 ◽

Cited By ~ 5

Author(s):

Aikebaier Maimaiti ◽

Amier Aili ◽

Hureshitanmu Kuerban ◽

Xuejun Li

Keyword(s):

Western Blot ◽

Cell Viability ◽

Gallic Acid ◽

Molecular Mechanisms ◽

A549 Cells ◽

Dependent Manner ◽

Lung Carcinoma Cells ◽

Induced Apoptosis ◽

The Impact

Aims: Gallic acid (GA) is generally distributed in a variety of plants and foods, and possesses cell growth-inhibiting activities in cancer cell lines. In the present study, the impact of GA on cell viability, apoptosis induction and possible molecular mechanisms in cultured A549 lung carcinoma cells was investigated. Methods: In vitro experiments showed that treating A549 cells with various concentrations of GA inhibited cell viability and induced apoptosis in a dose-dependent manner. In order to understand the mechanism by which GA inhibits cell viability, comparative proteomic analysis was applied. The changed proteins were identified by Western blot and siRNA methods. Results: Two-dimensional electrophoresis revealed changes that occurred to the cells when treated with or without GA. Four up-regulated protein spots were clearly identified as malate dehydrogenase (MDH), voltagedependent, anion-selective channel protein 1(VDAC1), calreticulin (CRT) and brain acid soluble protein 1(BASP1). VDAC1 in A549 cells was reconfirmed by western blot. Transfection with VDAC1 siRNA significantly increased cell viability after the treatment of GA. Further investigation showed that GA down regulated PI3K/Akt signaling pathways. These data strongly suggest that up-regulation of VDAC1 by GA may play an important role in GA-induced, inhibitory effects on A549 cell viability.

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Effects of Transport Medium Composition on in vitro Drug Permeation across Excised Pig Intestinal Tissue

Drug Delivery Letters ◽

10.2174/2210303110999201005214114 ◽

2020 ◽

Vol 10 ◽

Author(s):

Bianca Peterson ◽

Henrico Heystek ◽

Josias H. Hamman ◽

Johan D. Steyn

Keyword(s):

Medium Composition ◽

Screening Tests ◽

Intestinal Tissue ◽

Predictive Values ◽

Transport Medium ◽

Intestinal Fluids ◽

Lower Permeability ◽

The Impact ◽

Simulated Intestinal Fluids

Background:: Knowledge of the permeation characteristics of new chemical entities across biological membranes is essential to drug research and development. Transport medium composition may affect the absorption of compounds during in vitro drug transport testing. To preserve the predictive values of screening tests, the possible influence of transport media on the solubility of model drugs, and on the activities of tight junctions and efflux transporter proteins (e.g. P-glycoprotein) must be known. Objective:: The aim of this study was to compare the impact of different transport media on the bi-directional transport of standard compounds, selected from the four classes of the Biopharmaceutical Classification System (BCS), across excised pig intestinal tissue. Methods:: The Sweetana-Grass diffusion apparatus was used for the transport studies. Krebs-Ringer bicarbonate (KRB) buffer and simulated intestinal fluids in the fed (FeSSIF) and fasted (FaSSIF) states were used as the three transport media, while the chosen compounds were abacavir (BCS class 1), dapsone (BCS class 2), lamivudine (BCS class 3) and furosemide (BCS class 4). Results:: Abacavir exhibited lower permeability in both the simulated intestinal fluids than in the KRB buffer. Dapsone showed similar permeability in all media. Lamivudine exhibited lower permeability in FaSSIF than in the other two media. Furosemide exhibited improved transport with pronounced efflux in FaSSIF. Conclusion:: Different permeation behaviors were observed for the selected drugs in the respective media, which may have resulted from their different physico-chemical properties, as well as from the effects that dissimilar transport media components had on excised pig intestinal tissue.

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Introduction to geomicrobiology

10.1093/oso/9780198789406.003.0013 ◽

2018 ◽

Author(s):

David L. Kirchman

Keyword(s):

Fossil Fuels ◽

Solid Phase ◽

Direct Reduction ◽

Iron Oxidation ◽

Mineral Dissolution ◽

Precipitation Process ◽

Soluble Ions ◽

Chemolithoautotrophic Bacteria ◽

The Impact

Geomicrobiology, the marriage of geology and microbiology, is about the impact of microbes on Earth materials in terrestrial systems and sediments. Many geomicrobiological processes occur over long timescales. Even the slow growth and low activity of microbes, however, have big effects when added up over millennia. After reviewing the basics of bacteria–surface interactions, the chapter moves on to discussing biomineralization, which is the microbially mediated formation of solid minerals from soluble ions. The role of microbes can vary from merely providing passive surfaces for mineral formation, to active control of the entire precipitation process. The formation of carbonate-containing minerals by coccolithophorids and other marine organisms is especially important because of the role of these minerals in the carbon cycle. Iron minerals can be formed by chemolithoautotrophic bacteria, which gain a small amount of energy from iron oxidation. Similarly, manganese-rich minerals are formed during manganese oxidation, although how this reaction benefits microbes is unclear. These minerals and others give geologists and geomicrobiologists clues about early life on Earth. In addition to forming minerals, microbes help to dissolve them, a process called weathering. Microbes contribute to weathering and mineral dissolution through several mechanisms: production of protons (acidity) or hydroxides that dissolve minerals; production of ligands that chelate metals in minerals thereby breaking up the solid phase; and direct reduction of mineral-bound metals to more soluble forms. The chapter ends with some comments about the role of microbes in degrading oil and other fossil fuels.

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