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Methods in Molecular Biology (Clifton,... 2022The successful isolation of mycolactone in a laboratory or from a clinical sample relies on proper handling and storage of the toxin. Mycolactone is a light-sensitive...
The successful isolation of mycolactone in a laboratory or from a clinical sample relies on proper handling and storage of the toxin. Mycolactone is a light-sensitive and an amphiphilic toxin produced by Mycobacterium ulcerans. The biochemistry of the toxin makes it unstable in aqueous matrices such as blood, which causes it to self-aggregate or present in complex with carrier molecules. This biochemistry also impacts the use of the toxin in vitro, in that it tends to aggregate and stick to substrates in an aqueous environment, which alters its physiological presentation and limits its availability in a sample. Glass materials (i.e., tubes, vials, syringes, plates) should be used when possible to avoid loss of mycolactone sticking to plastic surfaces. Dark containers such as amber vials or aluminum-foil wrapped tubes should be used to avoid photodegradation of the toxin upon exposure to light. Sample storage in organic solvents is ideal for mycolactone stability and recovery; however, this is not always amenable as multiple diagnostic assays might be performed on a single sample (such as PCR or ELISA). In these cases, samples can be stored in an aqueous solution containing a small amount of detergent to enhance recovery of the toxin, and in order to avoid aggregation. Therefore, the downstream manipulations should be carefully considered prior to sample collection and storage. Here we present considerations for the optimal handling and storage of mycolactone in order to obtain quality yield of the toxin for various research and diagnostic applications.
Topics: Buruli Ulcer; Enzyme-Linked Immunosorbent Assay; Humans; Macrolides; Mycobacterium ulcerans; Photolysis
PubMed: 34643907
DOI: 10.1007/978-1-0716-1779-3_12 -
Molecules (Basel, Switzerland) Oct 2015Aromatic polyazides are widely used as starting materials in organic synthesis and photochemical studies, as well as photoresists in microelectronics and as... (Review)
Review
Aromatic polyazides are widely used as starting materials in organic synthesis and photochemical studies, as well as photoresists in microelectronics and as cross-linking agents in polymer chemistry. Some aromatic polyazides possess high antitumor activity, while many others are of considerable interest as high-energy materials and precursors of high-spin nitrenes and C₃N₄ carbon nitride nanomaterials. The use of aromatic polyazides in click-reactions may be a new promising direction in the design of various supramolecular systems possessing interesting chemical, physical and biological properties. This review is devoted to the synthesis, properties and applications of six-membered aromatic compounds containing three and more azido groups in the ring.
Topics: Azides; Click Chemistry; Heterocyclic Compounds; Nitriles; Phosphines; Photolysis
PubMed: 26506330
DOI: 10.3390/molecules201019142 -
Molecules (Basel, Switzerland) Jan 2016Volatile organic compounds (VOCs) are ubiquitous in indoor environments. Inhalation of VOCs can cause irritation, difficulty breathing, and nausea, and damage the... (Review)
Review
Volatile organic compounds (VOCs) are ubiquitous in indoor environments. Inhalation of VOCs can cause irritation, difficulty breathing, and nausea, and damage the central nervous system as well as other organs. Formaldehyde is a particularly important VOC as it is even a carcinogen. Removal of VOCs is thus critical to control indoor air quality (IAQ). Photocatalytic oxidation has demonstrated feasibility to remove toxic VOCs and formaldehyde from indoor environments. The technique is highly-chemical stable, inexpensive, non-toxic, and capable of removing a wide variety of organics under light irradiation. In this paper, we review and summarize the traditional air cleaning methods and current photocatalytic oxidation approaches in both of VOCs and formaldehyde degradation in indoor environments. Influencing factors such as temperature, relative humidity, deactivation and reactivations of the photocatalyst are discussed. Aspects of the application of the photocatalytic technique to improve the IAQ are suggested.
Topics: Air Pollution, Indoor; Catalysis; Formaldehyde; Humans; Light; Oxidation-Reduction; Photolysis; Temperature; Titanium; Volatile Organic Compounds; Volatilization
PubMed: 26742024
DOI: 10.3390/molecules21010056 -
Environment International Apr 2020In order to conduct a fast and comprehensive toxicity screening of pesticide transformation products (TPs), this study used a tiered approach by a combination of in... (Review)
Review
In order to conduct a fast and comprehensive toxicity screening of pesticide transformation products (TPs), this study used a tiered approach by a combination of in silico and experimental methods to determine the probability to be of relevance for risk assessment. The six pesticides Boscalid, Penconazole, Diuron, Terbutryn, Octhilinone (OIT), and Mecoprop were used as model compounds. Identification of corresponding environmental known and unknown TPs were done by literature analysis and photolysis experiments in combination. Aquatic solutions of the pesticides were photolysed to generate TPs which can be expected in the aquatic environment. The resulting mixtures were screened for TPs by high resolution LC-MS/MS. The herein developed approach was conducted at three different tiers: Literature review and in silico methods were used to predict exemplary the environmental bacterial toxicity and the genotoxicity of every single TP at tier I. In case of indications to be toxic, experiments at tier II were applied. Hereby, the photolytic mixtures containing parent compound and TPs were used for the consecutive toxicity test. Microtox assay for the parent compounds and the photolytic mixture was conducted to determine the acute and chronic toxicity and the growth inhibition of V. fischeri. Umu-tests were conducted to determine primary DNA damage. At tier III, single substance standards were used to conduct toxicity tests in case of toxic indication by previous tiers and availability of analytical standard. Identification of TPs revealed 45 known environmental TPs that originated from the six pesticides. The number of substances that need to be assessed was therefore more than sevenfold. By the tiered approach, it was possible to assess toxicological effects on environmental bacteria of 94% of the selected TPs. For 20% we found strong evidence to be toxic to environmental bacteria, as they were assessed at least at two tiers. For further 44% of the TPs we found slight evidence, as they could be assessed at one tier. Contrary, this approach turned out to be unsuitable to assess genotoxic effects of TPs neither by in silico tools nor by experiments. The number of substances that could probably pose a risk onto environment was quadrupled in comparison to the consideration of solely the parent compounds. Thus, this study demonstrates that the conducted screening approach allows for easy and fast identification of environmental relevant TPs. However, the study presented was a very first screening. Its applicability domain needs to be assessed further. For this purpose as a very next step the approach suggested here should be verified by applying additional endpoints and including additional parent compounds.
Topics: Chromatography, Liquid; DNA Damage; Ecotoxicology; Pesticides; Photolysis; Tandem Mass Spectrometry; Vibrio; Water Pollutants, Chemical
PubMed: 32113087
DOI: 10.1016/j.envint.2020.105533 -
International Journal of Molecular... Nov 2022Azathioprine (AZA) is a pharmacologic immunosuppressive agent administrated in various conditions such as autoimmune disease or to prevent the rejection of organ...
Azathioprine (AZA) is a pharmacologic immunosuppressive agent administrated in various conditions such as autoimmune disease or to prevent the rejection of organ transplantation. The mechanism of action is based on its biologically active metabolite 6-mercaptopurine (6-MP), which is converted, among others, into thioguanine nucleotides capable of incorporating into replicating DNA, which may act as a strong UV chromophore and trigger DNA oxidation. The interaction between azathioprine and DNA, before and after exposure to solar simulator radiation, was investigated using UV-vis spectrometry and differential pulse voltammetry at a glassy carbon electrode. The results indicated that the interaction of AZA with UV radiation was pH-dependent and occurred with the formation of several metabolites, which induced oxidative damage in DNA, and the formation of DNA-metabolite adducts. Moreover, the viability assays obtained for the L929 cell culture showed that both azathioprine and degraded azathioprine induced a decrease in cell proliferation.
Topics: Azathioprine; Photolysis; Mercaptopurine; DNA; Immunosuppressive Agents; DNA Adducts
PubMed: 36430909
DOI: 10.3390/ijms232214438 -
Journal of Photochemistry and... Dec 2020Gemmatimonas phototrophica is, so far, the only described phototrophic species of the bacterial phylum Gemmatimonadetes. Its cells contain a unique type of...
Gemmatimonas phototrophica is, so far, the only described phototrophic species of the bacterial phylum Gemmatimonadetes. Its cells contain a unique type of photosynthetic complex with the reaction center surrounded by a double ring antenna, however they can also grow in the dark using organic carbon substrates. Its photosynthesis genes were received via horizontal gene transfer from Proteobacteria. This raises two questions; how the horizontally transferred photosynthesis apparatus has integrated into the cellular machinery, and how much light-derived energy actually contributes to the cellular metabolism? To address these points, the photosynthetic reactions were studied on several levels, from photophysics of the reaction center to cellular growth. Flash photolysis measurements and bacteriochlorophyll fluorescence kinetic measurements documented the presence of fully functional type-2 reaction centers with a large light harvesting antenna. When illuminated, the bacterial cells reduced their respiration rate by 58 ± 5%, revealing that oxidative phosphorylation was replaced by photophosphorylation. Moreover, illumination also more than doubled the assimilation rates of glucose, a sugar that is mostly used for respiration. Finally, light increased the growth rates of Gemmatimonas phototrophica colonies on agar plates. All the presented data provide evidence that photosynthetic complexes are fully integrated into cellular metabolism of Gemmatimonas phototrophica, and are able to provide a substantial amount of energy for its metabolism and growth.
Topics: Bacteria; Bacterial Proteins; Bacteriochlorophylls; Kinetics; Oxidation-Reduction; Phosphorylation; Photolysis; Photosynthesis; Photosynthetic Reaction Center Complex Proteins; Spectrometry, Fluorescence
PubMed: 33220599
DOI: 10.1016/j.jphotobiol.2020.112085 -
Angewandte Chemie (International Ed. in... Feb 2021The mRNA modification N -methyladenosine (m A) is associated with multiple roles in cell function and disease. The methyltransferases METTL3-METTL14 and METTL16 act as...
The mRNA modification N -methyladenosine (m A) is associated with multiple roles in cell function and disease. The methyltransferases METTL3-METTL14 and METTL16 act as "writers" for different target transcripts and sequence motifs. The modification is perceived by dedicated "reader" and "eraser" proteins, but not by polymerases. We report that METTL3-14 shows remarkable cosubstrate promiscuity, enabling sequence-specific internal labeling of RNA without additional guide RNAs. The transfer of ortho-nitrobenzyl and 6-nitropiperonyl groups allowed enzymatic photocaging of RNA in the consensus motif, which impaired polymerase-catalyzed primer extension in a reversible manner. METTL16 was less promiscuous but suitable for chemo-enzymatic labeling using different types of click chemistry. Since both enzymes act on distinct sequence motifs, their combination allowed orthogonal chemo-enzymatic modification of different sites in a single RNA.
Topics: Adenosine; Chromatography, High Pressure Liquid; Click Chemistry; Humans; Light; Methyltransferases; Photolysis; RNA, Messenger; S-Adenosylmethionine; Substrate Specificity; Tandem Mass Spectrometry
PubMed: 33095964
DOI: 10.1002/anie.202013936 -
Indoor Air Jun 2022The importance of photolysis as an initiator of air chemistry outdoors is widely recognized, but its role in chemical processing indoors is often ignored. This paper...
The importance of photolysis as an initiator of air chemistry outdoors is widely recognized, but its role in chemical processing indoors is often ignored. This paper uses recent experimental data to modify a detailed chemical model, using it to investigate the impacts of glass type, artificial indoor lighting, cloudiness, time of year and latitude on indoor photolysis rates and hence indoor air chemistry. Switching from an LED to an uncovered fluorescent tube light increased predicted indoor hydroxyl radical concentrations by ~13%. However, moving from glass that transmitted outdoor light at wavelengths above 380 nm to one that transmitted sunlight above 315 nm led to an increase in predicted hydroxyl radicals of more than 400%. For our studied species, including ozone, nitrogen oxides, nitrous acid, formaldehyde, and hydroxyl radicals, the latter were most sensitive to changes in indoor photolysis rates. Concentrations of nitrogen dioxide and formaldehyde were largely invariant, with exchange with outdoors and internal deposition controlling their indoor concentrations. Modern lights such as LEDs, together with low transmission glasses, will likely reduce the effects of photolysis indoors and the production of potentially harmful species. Research is needed on the health effects of different indoor air mixtures to confirm this conclusion.
Topics: Air Pollutants; Air Pollution, Indoor; Formaldehyde; Hydroxyl Radical; Nitrous Acid; Photolysis
PubMed: 35762241
DOI: 10.1111/ina.13054 -
Molecules (Basel, Switzerland) Sep 2021This study investigated the direct and indirect photochemical degradation of citalopram (CIT), a selective serotonin reuptake inhibitor (SSRI), under natural and...
This study investigated the direct and indirect photochemical degradation of citalopram (CIT), a selective serotonin reuptake inhibitor (SSRI), under natural and artificial solar radiation. Experiments were conducted in a variety of different operating conditions including Milli-Q (MQ) water and natural waters (lake water and municipal WWT effluent), as well as in the presence of natural water constituents (organic matter, nitrate and bicarbonate). Results showed that indirect photolysis can be an important degradation process in the aquatic environment since citalopram photo-transformation in the natural waters was accelerated in comparison to MQ water both under natural and simulated solar irradiation. In addition, to investigate the decontamination of water from citalopram, TiO-mediated photocatalytic degradation was carried out and the attention was given to mineralization and toxicity evaluation together with the identification of by-products. The photocatalytic process gave rise to the formation of transformation products, and 11 of them were identified by HPLC-HRMS, whereas the complete mineralization was almost achieved after 5 h of irradiation. The assessment of toxicity of the treated solutions was performed by Microtox bioassay () and in silico tests showing that citalopram photo-transformation involved the formation of harmful compounds.
Topics: Catalysis; Citalopram; Photochemical Processes; Photolysis; Water
PubMed: 34500774
DOI: 10.3390/molecules26175331 -
Nature Cell Biology Oct 2016The dynamic instability of microtubules is characterized by slow growth phases stochastically interrupted by rapid depolymerizations called catastrophes. Rescue events...
The dynamic instability of microtubules is characterized by slow growth phases stochastically interrupted by rapid depolymerizations called catastrophes. Rescue events can arrest the depolymerization and restore microtubule elongation. However, the origin of these rescue events remains unexplained. Here we show that microtubule lattice self-repair, in structurally damaged sites, is responsible for the rescue of microtubule growth. Tubulin photo-conversion in cells revealed that free tubulin dimers can incorporate along the shafts of microtubules, especially in regions where microtubules cross each other, form bundles or become bent due to mechanical constraints. These incorporation sites appeared to act as effective rescue sites ensuring microtubule rejuvenation. By securing damaged microtubule growth, the self-repair process supports a mechanosensitive growth by specifically promoting microtubule assembly in regions where they are subjected to physical constraints.
Topics: Animals; Cell Membrane; Cells, Cultured; Focal Adhesion Kinase 1; Microtubule-Associated Proteins; Microtubules; Photolysis; Rats; Tubulin
PubMed: 27617929
DOI: 10.1038/ncb3406