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Methods in Molecular Biology (Clifton,... 2024Various bacterial species are associated with plant roots. However, symbiotic and free-living plant growth-promoting bacteria (PGPB) can only help plants to grow and...
Various bacterial species are associated with plant roots. However, symbiotic and free-living plant growth-promoting bacteria (PGPB) can only help plants to grow and develop under normal and stressful conditions. Several biochemical and in vitro assays were previously designed to differentiate between the PGPB and other plant-associated bacterial strains. This chapter describes and summarizes some of these assays and proposes a strategy to screen for PGPB. To determine the involvement of the PGPB in abiotic stress tolerance, assays for the ability to produce 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, ammonium, gibberellic acid (GA), indole acetic acid (IAA), and microbial volatile organic compounds (mVOCs) are described in this chapter. Additionally, assays to show the capacity to solubilize micronutrients such as potassium, phosphorus, and zinc by bacteria were also summarized in this chapter. To determine the contribution of the PGPB in biotic stress tolerance in plants, Fe-siderophore, hydrogen cyanide, and antibiotic and antifungal metabolites production assays were described. Moreover, assays to investigate the growth-promotion activities of a bacterium strain on plants, using the gnotobiotic root elongation, in vitro, and pots assays, were explained. Finally, an assay for the localization of endophytic bacterium in plant tissues was also presented in this chapter. Although the assays described in this chapter can give evidence of the nature of the mechanism behind the PGPB actions, other unknown growth-promoting means are yet to decipher, and until then, new methodologies will be developed.
Topics: Stress, Physiological; Bacteria; Plant Roots; Plant Growth Regulators; Plant Development; Indoleacetic Acids; Symbiosis; Plants; Soil Microbiology; Gibberellins; Volatile Organic Compounds
PubMed: 38869802
DOI: 10.1007/978-1-0716-3973-3_19 -
Plant, Cell & Environment Nov 2021Flooding is a major environmental constraint that obliges plants to adopt plastic responses in order to cope with it. When partially submerged, tomato plants undergo...
Flooding is a major environmental constraint that obliges plants to adopt plastic responses in order to cope with it. When partially submerged, tomato plants undergo profound changes involving rearrangements in their morphology and metabolism. In this work, we observed that partial submergence markedly dampens root respiration and halts root growth. However, the flooded hypocotyl surprisingly enhances oxygen consumption. Previous results demonstrated that aerenchyma formation in the submerged tomato stem re-establishes internal oxygen tension, making aerobic respiration possible. Indeed, potassium cyanide abruptly stops oxygen uptake, indicating that the cytochrome c pathway is likely to be engaged. Furthermore, we found out that leaf-derived sugars accumulate in large amounts in hypocotyls of flooded plants. Girdling and feeding experiments point to sucrose as the main carbon source for respiration. Consistently, submerged hypocotyls are characterized by high sucrose synthase activity, indicating that sucrose is cleaved and channelled into respiration. Since inhibition of hypocotyl respiration significantly prevents sugar build-up, it is suggested that a high respiration rate is required for sucrose unloading from phloem. As substrate availability increases, respiration is fuelled even more, leading to a maintained allocation of sugars to flooded hypocotyls.
Topics: Floods; Hypocotyl; Solanum lycopersicum; Plant Roots; Plant Stems; Sucrose
PubMed: 34268805
DOI: 10.1111/pce.14152 -
Drug Metabolism and Bioanalysis Letters Dec 2023Everolimus, an allosteric mechanistic target of rapamycin (mTOR) inhibitor, recently demonstrated the therapeutic value of mTOR inhibitors for Central Nervous System...
BACKGROUND
Everolimus, an allosteric mechanistic target of rapamycin (mTOR) inhibitor, recently demonstrated the therapeutic value of mTOR inhibitors for Central Nervous System (CNS) indications driven by hyperactivation of mTOR. A newer, potent brain-penetrant analog of everolimus, referred to as (1) in this manuscript [(S)-3-methyl-4-(7-((R)-3-methylmorpholino)-2-(thiazol-4-yl)-3H-imidazo[4,5-b]pyridin-5-yl)morpholine,(1)] catalytically inhibits mTOR function in the brain and increases the lifespan of mice with neuronal mTOR hyperactivation.
INTRODUCTION
Early evaluation of the safety of 1 was conducted in cynomolgus monkeys in which oral doses were administered to three animals in a rising-dose fashion (from 2 to 30 mg/kg/day). 1 produced severe toxicity including the evidence of hepatic toxicity, along with non-dose proportional increases in drug exposure. Investigations of cross-species hepatic bioactivation of 1 were conducted to assess whether the formation of reactive drug metabolites was associated with the mechanism of liver toxicity.
METHOD
1 contained two morpholine rings known as structural alerts and can potentially form reactive intermediates through oxidative metabolism. Bioactivation of 1 was investigated in rat, human and monkey liver microsomes fortified with trapping agents such as methoxylamine or potassium cyanide.
RESULTS
Our results suggest that bioactivation of the morpholine moieties to reactive intermediates may have been involved in the mechanism of liver toxicity observed with 1. Aldehyde intermediates trappable by methoxylamine were identified in rat and monkey liver microsomal studies. In addition, a total of four cyano conjugates arising from the formation of iminium ion intermediates were observed and identified. These findings may potentially explain the observed monkey toxicity. Interestingly, methoxylamine or cyano adducts of 1 were not observed in human liver microsomes.
CONCLUSION
The bioactivation of 1 appears to be species-specific. Circumstantial evidence for the toxicity derived from 1 point to the formation of iminium ion intermediates trappable by cyanide in monkey liver microsomes. The cyano conjugates were only observed in monkey liver microsomes, potentially pointing to cause at least the hepatotoxicity observed in monkeys. In contrast, methoxylamine conjugates were detected in both rat and monkey liver microsomes, with only a trace amount in human liver microsomes. Cyano conjugates were not observed in human liver microsomes, challenging the team on the drugability and progressivity of 1 through drug development. The mechanisms for drug-induced liver toxicity are multifactorial. These results are highly suggestive that the iminium ion may be an important component in the mechanism of liver toxicity 1 observed in the monkey.
PubMed: 38047363
DOI: 10.2174/0118723128260455231104180653 -
Clinical Toxicology (Philadelphia, Pa.) Jan 2022Cyanide is a rapid acting, lethal, metabolic poison and remains a significant threat. Current FDA-approved antidotes are not amenable or efficient enough for a mass...
BACKGROUND
Cyanide is a rapid acting, lethal, metabolic poison and remains a significant threat. Current FDA-approved antidotes are not amenable or efficient enough for a mass casualty incident.
OBJECTIVE
The objective of this study is to evaluate short and long-term efficacy of intramuscular aqueous dimethyl trisulfide (DMTS) on survival and clinical outcomes in a swine model of cyanide exposure.
METHODS
Anesthetized swine were instrumented and acclimated until breathing spontaneously. Potassium cyanide infusion was initiated and continued until 5 min after the onset of apnea. Subsequently, animals were treated with intramuscular DMTS ( = 11) or saline control ( = 10). Laboratory values and DMTS blood concentrations were assessed at various time points and physiological parameters were monitored continuously until the end of the experiment unless death occurred. A subset of animals treated with DMTS ( = 5) were survived for 7 days to evaluate muscle integrity by repeat biopsy and neurobehavioral outcomes.
RESULTS
Physiological parameters and time to apnea were similar in both groups at baseline and at time of treatment. Survival in the DMTS-treated group was 90% and 30% in saline controls ( = 0.0034). DMTS-treated animals returned to breathing at 12.0 ± 10.4 min (mean ± SD) compared to 22.9 ± 7.0 min (mean ± SD) in the 3 surviving controls. Blood collected prior to euthanasia showed improved blood lactate concentrations in the DMTS treatment group; 5.47 ± 2.65 mmol/L vs. 9.39 ± 4.51 mmol/L (mean ± SD) in controls ( = 0.0310). Low concentrations of DMTS were detected in the blood, gradually increasing over time with no elimination phase observed. There was no mortality, histological evidence of muscle trauma, or observed adverse neurobehavioral outcomes, in DMTS-treated animals survived to 7 days.
CONCLUSION
Intramuscular administration of aqueous DMTS improves survival following cyanide poisoning with no observed long-term effects on muscle integrity at the injection site or adverse neurobehavioral outcomes.
Topics: Animals; Antidotes; Cyanides; Humans; Potassium Cyanide; Sulfides; Swine
PubMed: 34142637
DOI: 10.1080/15563650.2021.1935992 -
Heliyon Jun 2023Spebrutinib is a new Bruton tyrosine kinase inhibitor developed by Avila Therapeutics and Celgene. Spebrutinib (SPB) is currently in phase Ib clinical trials for the...
Spebrutinib is a new Bruton tyrosine kinase inhibitor developed by Avila Therapeutics and Celgene. Spebrutinib (SPB) is currently in phase Ib clinical trials for the treatment of lymphoma in the United States. Preliminary studies were first performed to predict susceptible sites of metabolism, reactivity pathways and structural alerts for toxicities by StarDrop WhichP450™ module, Xenosite web predictor tool and DEREK software; respectively. SPB metabolites and adducts were characterized from rat liver microsomes (RLM) using LC-MS/MS. Formation of reactive intermediates was investigated using potassium cyanide (KCN), glutathione (GSH) and methoxylamine as trapping nucleophiles for the unstable and reactive iminium, iminoquinone and aldehyde intermediates, respectively, with the aim to produce stable adducts that can be detected and characterized using mass spectrometry. Fourteen phase I metabolites, four cyanide adducts, six GSH adducts and three methoxylamine adducts of SPB were identified and characterized. The proposed metabolic pathways involved in generation of phase I metabolites of SPB are oxidation, hydroxylation, -dealkylation, epoxidation, defluorination and reduction. Several reactive intermediates were identified and characterized, the formation of which can aid in explaining the adverse drug reactions of SPB. Several iminium, 2-iminopyrimidin-5()-one and aldehyde intermediates of SPB were revealed. Acrylamide is identified as a structural alert for toxicity by DEREK report and was found to be involved in the formation of several glycidamide and aldehyde reactive intermediates.
PubMed: 37484253
DOI: 10.1016/j.heliyon.2023.e17058 -
Clinical Toxicology (Philadelphia, Pa.) Jan 2020Cyanide is a metabolic poison used in multiple industries and is a high threat chemical agent. Current antidotes require intravenous administration, limiting their...
Cyanide is a metabolic poison used in multiple industries and is a high threat chemical agent. Current antidotes require intravenous administration, limiting their usefulness in a mass casualty scenario. Sodium tetrathionate reacts directly with cyanide yielding thiosulfate and the non-toxic compound thiocyanate. Thiosulfate, in turn, neutralizes a second molecule of cyanide, thus, per mole, sodium tetrathionate neutralizes two moles of cyanide. Historical studies examined its efficacy as a cyanide antidote, but it has not been evaluated in a clinically relevant, large animal model, nor has it previously been administered by intramuscular injection. The objective of this study is to evaluate the efficacy of intramuscular sodium tetrathionate on survival and clinical outcomes in a large, swine model of severe cyanide toxicity. Anesthetized swine were instrumented for continuous monitoring of hemodynamics, then acclimated and breathing spontaneously prior to potassium cyanide infusion (0.17 mg/kg/min). At 6-min post-apnea (no breaths for 20 s), the cyanide infusion was terminated, and animals were treated with sodium tetrathionate (∼18 mg/kg) or normal saline control. Clinical parameters and laboratory values were evaluated at various time points until death or termination of the experiment (90 min post-treatment). Laboratory values, vital signs, and time to apnea were similar in both groups at baseline and treatment. Survival in the sodium tetrathionate treated group was 100% and 17% in controls ( = 0.0043). All animals treated with sodium tetrathionate returned to breathing at a mean time of 10.85 min after antidote, and all but one control remained apneic through end of the experiment. Animals treated with tetrathionate showed improvement in blood lactate ( ≤ 0.002) starting at 30 min post-treatment. The average time to death in the control group is 63.3 ± 23.2 min. No systemic or localized adverse effects of intramuscular administration of sodium tetrathionate were observed. Sodium tetrathionate significantly improves survival and clinical outcomes in a large, swine model of acute cyanide poisoning.
Topics: Animals; Antidotes; Cyanides; Disease Models, Animal; Female; Injections, Intramuscular; Swine; Tetrathionic Acid
PubMed: 31008657
DOI: 10.1080/15563650.2019.1602272 -
Environmental Science and Pollution... Mar 2023Endophytic bacteria inhabit plant tissues such as roots, stems, leaves, fruits, and seeds and can multiply inside plant tissue without damaging them. This study involves...
Endophytic bacteria inhabit plant tissues such as roots, stems, leaves, fruits, and seeds and can multiply inside plant tissue without damaging them. This study involves the isolation, characterization, metabolic profiling, and effect of endophytic bacteria isolated from the roots of Scots pine (Pinus sylvestris), on the growth of sunflower. In the current study, fifteen isolates of endophytic bacteria were obtained from the roots of Scots pine, and their molecular characterization was performed using 16 s rRNA ribotyping. The molecular characterization revealed that the strains belonged to Bacillus spp., Pseudomonas spp., Micrococcus sp., Serratia sp., Enterobacter sp., Pantoea sp., Staphylococcus sp., and Microbacterium sp. Among the isolated strains, 9 strains showed positive results for ammonium production, 12 strains for calcium solubilization, 11 strains for magnesium solubilization, 5 strains for zinc solubilization, 12 strains for phosphate solubilization, 8 strains for potassium solubilization, 10 strains for indole acetic acid (IAA) production, 9 strains for siderophore, and 6 strains for hydrogen cyanide (HCN) production. The greenhouse experiment results demonstrated that all isolated endophytic bacteria improved the shoot length, dry weight, and chlorophyll content of sunflower, whereas a significant increase was observed by PS-3 (Bacillus cereus), PS-6 (Serratia marcescens), and PS-8 (Pseudomonas putida). Besides, the concentration of nitrogen, phosphorus, and potassium were also measured in sunflower shoots, and results asserted that bacterial inoculation increased the bioavailability of these essential nutrients to plants compared to uninoculated control. Thus, these endophytic bacteria could be used as an encouraging option to improve plant growth and performance.
Topics: Helianthus; Pinus sylvestris; Endophytes; Bacteria; Asteraceae; Metabolome; Plant Roots
PubMed: 36607575
DOI: 10.1007/s11356-022-25118-7 -
Ecotoxicology and Environmental Safety Oct 2022Hexavalent chromium [Cr (VI)] exists environmentally and occupationally. It has been shown to pose a carcinogenic hazard in certain occupations. This study was to...
Hexavalent chromium [Cr (VI)] exists environmentally and occupationally. It has been shown to pose a carcinogenic hazard in certain occupations. This study was to investigate the role of high mobility group A2 (HMGA2) in Cr (VI)-induced metabolism reprogramming from oxidative phosphorylation (OXPHOS) to glycolysis in A549 and HELF cells. First, knockdown of HMGA2 by siHMGA2 significantly attenuated Cr (VI)-reduced expression of OXPHOS-related proteins (COX IV and ND1) and mitochondrial mass, indicating that HMGA2 was involved in Cr (VI)-reduced OXPHOS. Overexpression of HMGA2 by transfection of HMGA2-DNA plasmids reduced the expression of COX IV, ND1 and mitochondrial mass, suggesting the negative role of HMGA2 in OXPHOS. Secondly, both CCCP, the inhibitor of mitochondrial function, and the ER stress inhibitor, 4-phenylbutyric acid (4-PBA), decreased the level of HMGA2, indicating that the interaction of mitochondrial dysfunction and ER stress resulted in Cr (VI)-induced HMGA2 expression. Further study demonstrated that ER stress/HMGA2 axis mediated the metabolism rewiring from OXPHOS to aerobic glycolysis. Notably, Cr (VI) induced the accumulation of HMGA2 proteins in mitochondria and ChIP assay demonstrated that HMGA2 proteins could bind to D-loop region of mitochondrial DNA (mtDNA), which provided the proof for HMGA2-modulating OXPHOS. Taken together, our results suggested that the interaction of mitochondria and ER stress-enhanced HMGA2 played an important role in Cr (VI)-induced metabolic reprogramming from OXPHOS to glycolysis by binding directly to D-loop region of mtDNA. This work informs on the potential mode of action for Cr (VI)-induced tumors and builds on growing evidence regarding the contribution of cellular metabolic disruption contributing to carcinogenicity.
Topics: Carbonyl Cyanide m-Chlorophenyl Hydrazone; Chromium; DNA, Mitochondrial; Glycolysis; Mitochondria
PubMed: 36116352
DOI: 10.1016/j.ecoenv.2022.114085 -
Chemical Communications (Cambridge,... Jan 2022We report two methods that use either NMR spectroscopy or direct magnetic susceptibility measurements for (strictly ) determination of the state of charge of redox flow...
We report two methods that use either NMR spectroscopy or direct magnetic susceptibility measurements for (strictly ) determination of the state of charge of redox flow batteries. These methods are demonstrated on the inorganic, redox-active potassium ferro/ferri cyanide catholyte cycled against 2,6-dihydroxyanthraquinone as the anolyte in a full cell, and should be applicable to a wide range of redox couples, provided that the magnetization of the electrolyte solution depends on its oxidation state.
PubMed: 34986212
DOI: 10.1039/d1cc01895g -
ACS Applied Materials & Interfaces Aug 2022Potassium ferricyanide in an aqueous solution is easily decomposed into highly toxic substances (potassium cyanide and hydrogen cyanide) by light or alkaline action,...
Potassium ferricyanide in an aqueous solution is easily decomposed into highly toxic substances (potassium cyanide and hydrogen cyanide) by light or alkaline action, which poses a major hazard to environmental and human health. Here, a reticulated aggregation-induced emission (AIE) supramolecular polymer material (TPAP-Mb@Q[14]) was prepared by the supramolecular self-assembly of twisted cucurbit[14]uril (Q[14]) and a triphenylamine derivative (TPAP-Mb). TPAP-Mb@Q[14] not only recognizes Fe(CN) with sensitive specificity with a limit of detection (LOD) of 1.64 × 10 M but can also effectively remove and adsorb Fe(CN) from an aqueous solution with a removal rate as high as 97.38%. Meanwhile, an important component of the supramolecular polymer material (Q[14]) can be reused. Thus, the Q[14]-based supramolecular assembly has the potential to be used for applications addressing toxic anionic contaminants present in aqueous environments.
PubMed: 35926157
DOI: 10.1021/acsami.2c10866