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We examined the mechanism by which the ochratoxin B induced interaction with calcium-channel antagonist verapamil and mitochondrial dysfunction of the rat trachea in vitro experiment. The tracheas were cut into 2-3 mm wide rings a...
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We examined the mechanism by which the ochratoxin B induced interaction with calcium-channel antagonist verapamil and mitochondrial dysfunction of the rat trachea in vitro experiment. The tracheas were cut into 2-3 mm wide rings and suspended in a tissue bath. Isometric tension was continuously measured with an isometric force transducer connected to a computer-based data acquisition system. Verapamil (1 x 10(-6) M) produced a concentration-dependent contraction response in rat's tracheal rings pre-contracted by acetylcholine. Incubation of rat's tracheal rings with the ochratoxin B significantly potentiated the contraction responses of verapamil. Verapamil and OTB accelerate the overloading of Ca2+ in tracheal smooth muscle contributes the tissue toxicity as shown in electron microscopy and mitochondrial enzymes, through a mechanism that could involve perturbations of Ca2+ homeostasis. These results proved that ochratoxin B is a potential vasoconstrictor mycotoxin with the presence of calcium-channel antagonist. In conclusion, disturbance of Ca2+ homeostasis caused by OTA and plays a significant role in produces toxicity through mitochondrial enzyme inhibition.
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? 2023 Elsevier B.V.Pathogenic species of Leptospira are recalcitrant for genetic manipulation using conventional tools, and therefore there is a need to explore techniques of higher efficiency. Application of endogenous CRISPR-Ca...
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? 2023 Elsevier B.V.Pathogenic species of Leptospira are recalcitrant for genetic manipulation using conventional tools, and therefore there is a need to explore techniques of higher efficiency. Application of endogenous CRISPR-Cas tool is emerging and efficient; nevertheless, it is limited by a poor understanding of interference machinery in the bacterial genome and its associated protospacer adjacent motif (PAM). In this study, interference machinery of CRISPR-Cas subtype I-B (Lin_I-B) from L. interrogans was experimentally validated in E. coli using the various identified PAM (TGA, ATG, ATA). The overexpression of the Lin_I-B interference machinery in E. coli demonstrated that LinCas5, LinCas6, LinCas7, and LinCas8b can self-assemble on cognate CRISPR RNA to form an interference complex (LinCascade). Moreover, a robust interference of target plasmids containing a protospacer with a PAM suggested a functional LinCascade. We also recognized a small open reading frame within lincas8b that independently co-translates into LinCas11b. A mutant variant LinCascade-Cas11b that lacks LinCas11b co-expression erred to mount target plasmid interference. At the same time, LinCas11b complementation in LinCascade-Cas11b rescued target plasmid interference. Thus, the present study establishes Leptospira subtype I-B interference machinery to be functional and, soon, may pave the way for scientists to harness it as a programmable endogenous genetic manipulation tool.
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Plasma membrane Ca2+-ATPases are key calcium exporter proteins in most tissues, and PMCA4b is the main calcium transporter in the human red blood cells (RBCs). In order to assess the expression level of PMCA4b, we have developed a...
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Plasma membrane Ca2+-ATPases are key calcium exporter proteins in most tissues, and PMCA4b is the main calcium transporter in the human red blood cells (RBCs). In order to assess the expression level of PMCA4b, we have developed a flow cytometry and specific antibody binding method to quantitatively detect this protein in the erythrocyte membrane. Interestingly, we found several healthy volunteers showing significantly reduced expression of RBC-PMCA4b. Western blot analysis of isolated RBC membranes confirmed this observation, and indicated that there are no compensatory alterations in other PMCA isoforms. In addition, reduced PMCA4b levels correlated with a lower calcium extrusion capacity in these erythrocytes. When exploring the potential genetic background of the reduced PMCA4b levels, we found no missense mutations in the ATP2B4 coding regions, while a formerly unrecognized minor haplotype in the predicted second promoter region closely correlated with lower erythrocyte PMCA4b protein levels. In recent GWA studies, SNPs in this ATP2B4 haplotype have been linked to reduced mean corpuscular hemoglobin concentrations (MCEIC), and to protection against malaria infection. Our data suggest that an altered regulation of gene expression is responsible for the reduced RBC-PMCA4b levels that is probably linked to the development of human disease-related phenotypes. (c) 2017 Elsevier Ltd. All rights reserved.
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Aflatoxin B1 (AFB1) contamination in food threatens global food safety, and rapid quantitative detection of AFB1 remains a challenge. Herein, a novel fluorescence biosensor was developed for AFB1 detection based on CRISPR/Cas12a a...
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Aflatoxin B1 (AFB1) contamination in food threatens global food safety, and rapid quantitative detection of AFB1 remains a challenge. Herein, a novel fluorescence biosensor was developed for AFB1 detection based on CRISPR/Cas12a and MXenes. Specifically, the well-designed activator was locked by dual-AFB1 aptamers, Cas12a was directly linked to crRNA to form inactivated complexes, and MXenes efficiently adsorbed FAM fluorophore-modified single-stranded DNA (ssDNA-FAM), quenching its fluorescence. In the presence of AFB1, the activator was released due to the preferential binding of the aptamer to AFB1, and the released activator then activated the trans- cleavage activity of Cas12a to indiscriminately cleave ssDNA on MXenes, leading to the recovery of the fluorescence signal. The fluorescent biosensor had a wide detection range from 0.001 to 80?ng?mL ?1 , a detection limit of 0.92?pg?mL ?1 , and the ability to detect within 80?min. More importantly, the platform demonstrates excellent detection performance in real peanut samples.
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The trace element composition of planktic foraminiferal calcite provides a useful means of determining past surface ocean conditions. We have assembled the results of culture experiments for three species of symbiont-bearing plank...
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The trace element composition of planktic foraminiferal calcite provides a useful means of determining past surface ocean conditions. We have assembled the results of culture experiments for three species of symbiont-bearing planktic foraminifera, Globigerinoides ruber, Globigerinoides sacculifer, and Orbulina universa, and one symbiont-barren species, Globigerina bulloides, to evaluate their responses to temperature, salinity, pH, carbonate ion, and dissolved inorganic carbon (DIC) growth conditions. Trace element ratios (Li/Ca, B/Ca, Mg/Ca, Sr/Ca, Mn/Ca, Cd/Ca, Ba/Ca, Na/Ca, and U/Ca) were measured simultaneously on samples grown with the same culture techniques, which provides robust, relatable calibrations that may be used together in multi-proxy paleoceanographic studies. Our data confirm that temperature is the dominant control on foraminiferal Mg/Ca under the ranges of conditions studied and that the potential effects of salinity and CO32- on Mg/Ca of these tropical species across late Pleistocene glacial cycles are relatively small. Carbonate system experiments suggest that Sr/Ca may be useful for reconstructing large DIC changes. Na/Ca increases with salinity in G. ruber (pink), but not in G. sacculifer. As these emerging proxy relationships become more firmly established, the synthesis of multiple trace element ratios may help paleoceanographers isolate the effects of different environmental parameters in paleo records. Calcification rates (mu g/day) vary among species and do not respond consistently to any experimental parameter. Comparison of our calcification rates with those observed in inorganic calcite precipitation experiments suggest that foraminifera calcify similar to 100x more slowly than inorganic calcites grown in similar solutions. We suggest that calcification rate does not typically exert a dominant control on trace element partitioning in planktic foraminiferal calcite, though it may play a role for some elements under certain circumstances. Differences in average growth rate cannot explain composition differences among species, pointing to alternative controls that may be biological in origin. (C) 2016 Elsevier Ltd. All rights reserved.
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Loss-of-function mutations in the cytoskeletal protein ankyrin-B (AnkB) cause ventricular tachyarrhythmias in humans. Previously, we found that a larger fraction of the sarcoplasmic reticulum (SR) Ca2+ leak occurs through Ca2+ spa...
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Loss-of-function mutations in the cytoskeletal protein ankyrin-B (AnkB) cause ventricular tachyarrhythmias in humans. Previously, we found that a larger fraction of the sarcoplasmic reticulum (SR) Ca2+ leak occurs through Ca2+ sparks in AnkB-deficient (AnkB(+/-)) mice, which may contribute to arrhythmogenicity via Ca2+ waves. Here, we investigated the mechanisms responsible for increased Ca2+ spark frequency in AnkB(+/-) hearts.
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Reliable reconstructions of deep ocean carbonate ion concentration, [CO32-], and pH are crucial to understand mechanisms responsible for the past atmospheric CO2 variations observed in ice cores. However, it is challenging to reco...
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Reliable reconstructions of deep ocean carbonate ion concentration, [CO32-], and pH are crucial to understand mechanisms responsible for the past atmospheric CO2 variations observed in ice cores. However, it is challenging to reconstruct past deep water [CO32-] and pH and literature results from different proxies conflict, warranting careful investigations on possible reasons for the existing inconsistencies. Here, we present the first down core B/Ca and delta B-11 records measured in an epifaunal benthic foraminifer Cibicidoides wuellerstorfi from the Caribbean Sea during the last 160 kyr. The two proxies yield quantitatively comparable deep water [CO32-] and pH results, showing high values during glacials relative to inter-glacials (differences in [CO32-] and pH are similar to 35 mu mol/kg and similar to 0.15, respectively), consistent with past ocean circulation changes in the Caribbean Sea. Our data provide convincing evidence that both proxies serve as faithful proxies to estimate deep ocean [CO32-] and pH, despite our incomplete understanding of boron incorporation into foraminiferal carbonates. Published by Elsevier B.V.
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The isotopic ratio and concentration of B in foraminiferal calcite appear to reflect the pH and bicarbonate concentration of seawater. The use of B as a chemical proxy tracer has the potential to transform our understanding of the...
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The isotopic ratio and concentration of B in foraminiferal calcite appear to reflect the pH and bicarbonate concentration of seawater. The use of B as a chemical proxy tracer has the potential to transform our understanding of the global carbon cycle, and ocean acidification processes. However, discrepancies between the theory underpinning the B proxies, and mineralogical observations of B coordination in biomineral carbonates call the basis of these proxies into question. Here, we use synchrotron X-ray spectromicroscopy to show that B is hosted solely as trigonal BO3 in the calcite test of Amphistegina lessonii, and that B concentration exhibits banding at the micron length scale. In contrast to previous results, our observation of trigonal B agrees with the predictions of the theoretical mechanism behind B palaeoproxies. These data strengthen the use of B for producing palaeo-pH records. The observation of systematic B heterogeneity, however, highlights the complexity of foraminiferal biomineralisation, implying that B incorporation is modulated by biological or crystal growth processes. (C) 2015 The Authors. Published by Elsevier B.V.
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YVO_4 single crystals doped with CaO are grown by the floating zone method in nitrogen atmosphere. The crystal is colorless and transparent after annealing in oxygen atmosphere. The effects of CaO addition are discussed. The Ca~(2...
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YVO_4 single crystals doped with CaO are grown by the floating zone method in nitrogen atmosphere. The crystal is colorless and transparent after annealing in oxygen atmosphere. The effects of CaO addition are discussed. The Ca~(2+) ions can substitute for Y~(3+) at Y-sites in the YVO_4 structure to form oxygen vacancies via which oxide ions can easily diffuse and, consequently, yield transparent crystals.
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На уровне организации ДНК в хроматин работают механизмы, определяющие профиль экспрессии генов в специализированных клетках...
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На уровне организации ДНК в хроматин работают механизмы, определяющие профиль экспрессии генов в специализированных клетках. Гены в составе хроматина, который находится на периферии клеточного ядра, как правило, имеют сниженный уровень экспрессии, однако природа этого явления все еще не ясна. Такие районы хроматина взаимодействуют с белками ядерной ламины, например, с белком Lamin В1, и могут быть определены путем выявления (картирования) взаимодействий этих белков с геномной ДНК. В данном исследовании мы разработали и испытали систему Dam Identification (DamID), индуцируемую сайт-специ-фической рекомбиназой Сге, на примере белка Lamin B1 и культуры клеток эмбриональных фибробластов мыши. Эта система может быть применена для картирования взаимодействий белков хроматина с геномной ДН Кпотдельных типах клеток и тканей животных. Преимущество подхода заключается в отсутствии необходимости физически выделять исследуемый тип клеток из ткани или ткань из органа, что обеспечивается применением специфических регуляторных элементов ДНК и высокой чувствительностью метода.
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