Accumulation Of Hydrogen Sulfide Research Articles

Microbial Corrosion of Copper Under Conditions Simulating Deep Radioactive Waste Disposal.

This paper presents the results of microbial corrosion tests on M0-grade copper under conditions simulating a geological repository for radioactive waste at the Yeniseisky site (Krasnoyarsk Krai, Russia). The work used a microbial community sampled from a depth of 450 m and stimulated with glucose, hydrogen and sulfate under anaerobic conditions. It was shown that the maximum corrosion rate, reaching 9.8 µm/y, was achieved with the addition of sulfate (1 g/L) with the participation of microorganisms from the families Desulfomicrobiaceae, Desulfovibrionaceae and Desulfuromonadaceae. It was noted that the most important factor leading to copper corrosion was the accumulation of hydrogen sulfide during the activation of sulfate-reducing microorganisms of the genera Desulfomicrobium, Desulfovibrio and Desulfuromonas. During the development of the microbial community under these conditions, the content of copper can have a significant toxic effect at a concentration of more than 250 mg/L.

Non-thermal atmospheric pressure plasma-irradiated cysteine protects cardiac ischemia/reperfusion injury by preserving supersulfides

Ischemic heart disease is the main global cause of death in the world. Abnormal sulfide catabolism, especially hydrogen sulfide accumulation, impedes mitochondrial respiration and worsens the prognosis after ischemic insults, but the substantial therapeutic strategy has not been established. Non-thermal atmospheric pressure plasma irradiation therapy is attracted attention as it exerts beneficial effects by producing various reactive molecular species. Growing evidence has suggested that supersulfides, formed by catenation of sulfur atoms, contribute to various biological processes involving electron transfer in cells. Here, we report that non-thermal plasma-irradiated cysteine (Cys∗) protects mouse hearts against ischemia/reperfusion (I/R) injury by preventing supersulfide catabolism. Cys∗ has a weak but long-lasting supersulfide activity, and the treatment of rat cardiomyocytes with Cys∗ prevents mitochondrial dysfunction after hypoxic stress. Cys∗ increases sulfide-quinone oxidoreductase (SQOR), and silencing SQOR abolishes Cys∗-induced supersulfide formation and cytoprotection. Local administration of mouse hearts with Cys∗ significantly reduces infarct size with preserving supersulfide levels after I/R. These results suggest that maintaining supersulfide formation through SQOR underlies cardioprotection by Cys∗ against I/R injury.

Advanced nitrate removal in sulfur autotrophic denitrification biofilter under dissolved oxygen shock and low temperature enhanced by boron oxide and magnesium oxide: Hydrogen sulfide accumulation and regulation

Strengthening nitrate removal stability of sulfur autotrophic denitrification (SAD) under environmental stress is of great urgency. This study established a biofilter filled with S0-based filter material modified by boron oxide and magnesium oxide (FMSBMg). Hydrogen sulfide (H2S) accumulation reached 18.89 ± 4.51 mg/L and 7.28 ± 2.03 mg/L in summer and winter. Air and water backwash flow rates of 3 m3/h and 150 L/h could reduce H2S accumulation to below 0.16 mg/L under dissolved oxygen (DO) of 4.4 ± 0.1 mg/L 0.4 ± 0.1 mg/L B3+ and 15.9 ± 0.3 mg/L Mg2+ released from FMSBMg enhanced nitrate removal stability under DO shock and temperature drop. NO3−-Neff reached 5.2 ± 2.2 mg/L at 12.1 ± 0.8 °C. Coexistence of NH4+-N and NO2−-N provided substrates for in situ enrichment of Anammox bacteria. Thiobacillus, Lysobacter and Brocadia abundances accounted for 53.9%, 2.5% and 1.8% in biofilter, respectively. This study could provide theoretical basis for SAD biofilter application and H2S regulation.

The lake cod Gadus morhua kildinensis in the context of conservation biology

Atlantic cod, Gadus morhua, is a marine fish, but there are several Arctic lakes, where it also occurs. Mogilnoye Lake on Kildin Island in the Barents Sea is especially famous for them. It is a salinity stratified meromictic lake. The surface layer is fresh with saline water saturated with hydrogen sulfide underneath. Kildin cod have been studied over the last 100 years with emphasis on taxonomy, physiology, genetics and growth. However, the conservation of this species has been overlooked. Recent sonar surveys showed that the cod are quite abundant, but in danger from hydrogen sulfide accumulation within the lower lake levels. Therefore, the habitat of this species is shrinking. Conservation studies must be a priority in the situations like this.

Charge Density-Regulated Microchannel-Based Electrochemiluminescence Sensor for Hydrogen Sulfide Detection with a Highly Efficient Accumulation Strategy.

The electrochemiluminescence (ECL) intensity can be regulated by ionic current passing through the microchannel, which broadened the regulation of the ECL sensors. But in the early reported sensors, the electrostatic repulsion and steric hindrance caused few targets to approach the interface of the microchannel driven by concentration difference, which reduced the detection efficiency and prolonged the detection period. In this study, different accumulation strategies, such as a positive electric field and different polarity electric fields, were designed to accumulate targets in the microchannel. The interaction of azide groups and hydrogen sulfide served as a research model. Hydrogen sulfide can react with the negatively charged azide groups in the microchannel surface to produce positively charged amino groups, decreasing the negative charge density of the microchannel and thus altering the ionic current and ECL intensity. The accumulation of hydrogen sulfide at the microchannel tip can increase the collision probability with azide groups to improve the detection efficiency, and the integration of accumulation and reaction can shorten the detection period to 28 min. The hydrogen sulfide concentration on the microchannel tip accumulated by applying different polarity electric fields was 22.3-fold higher than that accumulated by applying a positive electric field. The selected research model broadened the application range of a microchannel-based ECL sensor and confirmed the universality of the microchannel-based ECL sensor.

Cardiac Remodeling: Novel Pathophysiological Mechanisms and Therapeutic Strategies.

Morphological and structural remodeling of the heart, including cardiac hypertrophy and fibrosis, has been considered a therapeutic target for heart failure for approximately three decades. Groundbreaking heart failure medications demonstrating reverse remodeling effects have contributed significantly to medical advancements. However, nearly 50% of heart failure patients still exhibit drug resistance, posing a challenge to the healthcare system. Recently, characteristics of heart failure resistant to ARBs and β-blockers have been defined, highlighting preserved systolic function despite impaired diastolic function, leading to the classification of heart failure with preserved ejection fraction (HFpEF). The pathogenesis and etiology of HFpEF may be related to metabolic abnormalities, as evidenced by its mimicry through endothelial dysfunction and excessive intake of high-fat diets. Our recent findings indicate a significant involvement of mitochondrial hyper-fission in the progression of heart failure. This mitochondrial pathological remodeling is associated with redox imbalance, especially hydrogen sulfide accumulation due to abnormal electron leak in myocardium. In this review, we also introduce a novel therapeutic strategy for heart failure from the current perspective of mitochondrial redox-metabolic remodeling.

Гуанідінійвмісний олігомер як інгібітор мікробної корозії металу

Guanidinium-containing oligomers, a poorly studied class of organic compounds, have attracted attention due to their bactericidal properties. A guanidinium-containing oligomer based on an aliphatic oligoepoxide is a newly synthesized substance with bactericidal activity, which gives it the prospects for use as a microbial corrosion inhibitor. Aim. The goal of the study was to synthesize oligomeric alkyl substituted guanidinium bromide and study of its anticorrosive properties in the presence of steel under the influence of corrosive active sulfate-reducing bacteria. Methods. The guanidine-containing alkyl substituted oligomer was obtained by the reaction of the aliphatic oligoepoxide DEG-1 with guanidine, followed by interaction with alkyl bromide. The anticorrosive properties of the guanidine-containing oligomer were studied using collection strains of sulfate-reducing bacteria: UCM B-11503 Desulfovibrio sp.10, UCM B-11501 Desulfovibrio desulfuricans DSM642, and UCM B-11502 Desulfovibrio vulgaris DSM644. The sulfate-reducing bacteria were grown on Postgate В medium for 14 days at a temperature of 28 ± 2 °C. The number of bacteria was determined by the method of tenfold dilution. The corrosion rate was determined by the gravimetric method. The physicochemical parameters of pH and redox potential of the bacterial culture liquid were studied by the potentiometric method. The accumulation of hydrogen sulfide in the culture liquid was determined by the iodometric method. Lipolytic activity was studied spectrophotometrically using a KFK-3 device by reaction with p-nitrophenyl palmitate, catalase activity — using 0.03% hydrogen peroxide, which formed a stable colored complex with a 4% molybdenum diphosphate solution. The specific activity of the studied enzymes was expressed as unit ∙ mg-1 protein. Protein was determined in the supernatant by the conventional Lowry method. Results. It was shown that the oligomer based on aliphatic oligoepoxide has biocidal properties. A significant inhibition of the development of sulfate-reducing bacteria (SRB) was observed after the oligomer was added; only dozens of bacterial cells were detected in the medium after the exposure period. The corrosion rate of steel in the presence of SBR without addition of inhibitors was 0.15 — 0.35 mg/cm2∙h. The addition of DPC (a quaternary ammonium compound based on N-decylpyridinium chloride) (Kyiv Polytechnic Institute (KPI), Ukraine) to the culture medium led to a decrease in the steel corrosion rate to 0.032 — 0.047 mg ∙ cm-2 h-1 (by 6.5—10.6 times). In the presence of Armohib CI-28 inhibitor (based on Diamine Ethoxylate) (Akzonobel, Holland), the corrosion rate was reduced to 0.02—0.039 mg ∙ cm-2 h-1 (by 4.2 — 12.7 times). The addition of guanidinium-containing oligomer to the medium with bacteria reduced the corrosion rate to 0.075—0.079 mg/cm2 ∙ h (by 2.5—2.7 times). According to the mass loss of steel samples, the degree of metal protection against microbial corrosion in the presence of guanidinium-containing oligomer was 60.15—63.17%. Conclusions. The obtained data indicate that the guanidinium-containing oligomer based on aliphatic oligoepoxy has biocidal and anticorrosive properties and is promising for use as a means of combating microbially induced corrosion.

Hydrogen Sulfide in the Oxidative Stress Response of Plants: Crosstalk with Reactive Oxygen Species.

Growing evidence suggests that exposure of plants to unfavorable environments leads to the accumulation of hydrogen sulfide (H2S) and reactive oxygen species (ROS). H2S interacts with the ROS-mediated oxidative stress response network at multiple levels. Therefore, it is essential to elucidate the mechanisms by which H2S and ROS interact. The molecular mechanism of action by H2S relies on the post-translational modification of the cysteine sulfur group (-SH), known as persulfidation. H2S cannot react directly with -SH, but it can react with oxidized cysteine residues, and this oxidation process is induced by H2O2. Evidently, ROS is involved in the signaling pathway of H2S and plays a significant role. In this review, we summarize the role of H2S-mediated post-translational modification mechanisms in oxidative stress responses. Moreover, the mechanism of interaction between H2S and ROS in the regulation of redox reactions is focused upon, and the positive cooperative role of H2S and ROS is elucidated. Subsequently, based on the existing evidence and clues, we propose some potential problems and new clues to be explored, which are crucial for the development of the crosstalk mechanism of H2S and ROS in plants.

Disruption of Bioenergetics in the Intestine of Wistar Rats Caused by Hydrogen Sulfide and Thiosulfate: A Potential Mechanism of Chronic Hemorrhagic Diarrhea in Ethylmalonic Encephalopathy.

Ethylmalonic encephalopathy (EE) is a severe inherited metabolic disorder that causes tissue accumulation of hydrogen sulfide (sulfide) and thiosulfate in patients. Although symptoms are predominantly neurological, chronic hemorrhagic diarrhea associated with intestinal mucosa abnormalities is also commonly observed. Considering that the pathophysiology of intestinal alterations in EE is virtually unknown and that sulfide and thiosulfate are highly reactive molecules, the effects of these metabolites were investigated on bioenergetic production and transfer in the intestine of rats. We observed that sulfide reduced NADH- and FADH2-linked mitochondrial respiration in the intestine, which was avoided by reduced glutathione (GSH) but not by melatonin. Thiosulfate did not change respiration. Moreover, both metabolites markedly reduced the activity of total, cytosolic and mitochondrial isoforms of creatine kinase (CK) in rat intestine. Noteworthy, the addition of GSH but not melatonin, apocynin, and Trolox (hydrosoluble vitamin E) prevented the change in the activities of total CK and its isoforms caused by sulfide and thiosulfate, suggesting a direct protein modification on CK structure by these metabolites. Sulfide further increased thiol content in the intestine, suggesting a modulation in the redox state of these groups. Finally, sulfide and thiosulfate decreased the viability of Caco-2 intestinal cells. Our data suggest that bioenergetic impairment caused by sulfide and thiosulfate is a mechanism involved in the gastrointestinal abnormalities found in EE.

Impakt of Ozone on the Oxyge Affinity Blood Properties and Prooxidant–Antioxidant Balance under Effect of H<sub>2</sub>S-Generating System

Hydrogen sulfide belongs to the group of signaling agents called gaseous transmitters and plays an important role in many physiological processes, in particular, in the realization of oxygen-dependent mechanisms. The aim of this study was to evaluate the significance of hydrogen sulfide in the effect of ozone on the oxygen affinity blood properties and the prooxidant-antioxidant balance in vitro experiment. Ozone (6 mg/L concentration) and drugs that affect the synthesis of hydrogen sulfide (propargylglycine, sodium hydrosulfide and its combination with nitroglycerin) were used. The use of propargylglycine, an inhibitor of the synthesis of hydrogen sulfide, leads to a decrease in the effect of ozone on the blood oxygen transport function (decrease in PO2, SO2, P50real). When sodium hydrosulfide is added, the effect of this gas on these parameters does not increase, but in its combination with nitroglycerin, the effect of ozone on the blood oxygen transport function increases. Propargylglycine does not affect the prooxidant-antioxidant balance under the conditions of the experiment, and donors of hydrogen sulfide and nitrogen monoxide increase the activity of catalase. Propargylglycine under the action of ozone leads to a decrease in the level of nitrate/nitrite, and sodium hydrosulfide increases their concentration. The combination of sodium hydrosulfide and nitroglycerin leads to the accumulation of hydrogen sulfide in the blood plasma.

Hydrogen sulfide delays yellowing and softening, inhibits nutrient loss in postharvest celery

Celery is an important leafy vegetable crop and is widely used in fresh food consumption and processing. Therefore, the preservation of fresh cut celery is warranted. As a food preservative, sodium hydrosulfide has been used to maintain postharvest quality of crops. However, the role of sodium hydrosulfide in the preservation of postharvest celery remains unclear. Here, by regulating endogenous hydrogen sulfide content with sodium hydrosulfide and hypotaurine, we evaluated the effects of sodium hydrosulfide on postharvest celery quality. Sodium hydrosulfide treatment promoted endogenous hydrogen sulfide accumulation by triggering AgLCD and AgSAT expression, as well as increased activity of L-cysteine desulfhydrase, D-cysteine desulfhydrase, O-acetylserine (thiol)lyase, and serine acetyltransferase. Simultaneously, sodium hydrosulfide treatment enhanced the expression of AgSOD1, AgPOD, and AgCAT, improved the activities of superoxide dismutase, peroxidase, and catalase, and inhibited the accumulation of malondialdehyde, hydrogen peroxide, and superoxide anion, thereby reducing electrolyte leakage of the cell membrane. AgPAL and AgCAD expressions were up-regulated, and phenylalanine ammonia-lyase and cinnamyl alcohol dehydrogenase activities were increased to promote lignin synthesis and alleviate the softening process. AgPAO and AgPPH expression was down-regulated, polyamine oxidases and pheophytinase activities were decreased to inhibit chlorophyll degradation and delay yellowing. Meanwhile, sodium hydrosulfide treatment effectively inhibited nutrient loss, including soluble sugar, soluble protein, vitamin C, carotenoids, and total phenols. Our findings suggest that hydrogen sulfide plays an essential role in delaying quality deterioration of postharvest celery, while sodium hydrosulfide treatment is a promising method for celery preservation.

Echinochrome Prevents Sulfide Catabolism-Associated Chronic Heart Failure after Myocardial Infarction in Mice.

Abnormal sulfide catabolism, especially the accumulation of hydrogen sulfide (H2S) during hypoxic or inflammatory stresses, is a major cause of redox imbalance-associated cardiac dysfunction. Polyhydroxynaphtoquinone echinochrome A (Ech-A), a natural pigment of marine origin found in the shells and needles of many species of sea urchins, is a potent antioxidant and inhibits acute myocardial ferroptosis after ischemia/reperfusion, but the chronic effect of Ech-A on heart failure is unknown. Reactive sulfur species (RSS), which include catenated sulfur atoms, have been revealed as true biomolecules with high redox reactivity required for intracellular energy metabolism and signal transduction. Here, we report that continuous intraperitoneal administration of Ech-A (2.0 mg/kg/day) prevents RSS catabolism-associated chronic heart failure after myocardial infarction (MI) in mice. Ech-A prevented left ventricular (LV) systolic dysfunction and structural remodeling after MI. Fluorescence imaging revealed that intracellular RSS level was reduced after MI, while H2S/HS- level was increased in LV myocardium, which was attenuated by Ech-A. This result indicates that Ech-A suppresses RSS catabolism to H2S/HS- in LV myocardium after MI. In addition, Ech-A reduced oxidative stress formation by MI. Ech-A suppressed RSS catabolism caused by hypoxia in neonatal rat cardiomyocytes and human iPS cell-derived cardiomyocytes. Ech-A also suppressed RSS catabolism caused by lipopolysaccharide stimulation in macrophages. Thus, Ech-A has the potential to improve chronic heart failure after MI, in part by preventing sulfide catabolism.

EVALUATION OF SOME GREENHOUSE GASES EMISSIONS FROM LANDFILL MODELS OF MUNICIPAL SOLID WASTE

Major greenhouse gases emissions (GHGs) that cause diseases and global warming evaporate from waste disposal in landfills. For this reason waste management skills in landfills have to be revised, otherwise the magnitude of ozone layer will decrease even more and the global warming consequences will get more obviously on the environmental scale. The resent situation on waste disposal and GHGs from European Union landfills were analyzed in this article. According to survey made in one Lithuanian landfill, the average amount of municipal biodegradable waste is 58%. The research study describes current GHGs emissions quantitative analysis from five laboratory scale municipal solid waste landfill models with different conditions. Conditions in all columns were differed by changing the inlet and outlet flows of air, water/leachate, and probiotics. The object of research is the accumulation of hydrogen sulfide (H2S) and oxygen (O2) from municipal solid waste landfill models. After analysis and assessment of emitted GHG’s from the municipal solid waste landfill models, the landfill model with the lowest emissions was identified. Suitable landfill model’s condition parameters helps to reduce greenhouse gas emissions and shorten landfill aftercare period.

Effect of high temperature and sulfur vapor on the flammability limit of hydrogen sulfide

In the process of removing hydrogen sulfide from natural gas, it is easy to form an accumulation of hydrogen sulfide in the gas phase space of the liquid sulfur tank, which can lead to an explosion accident. In order to avoid an explosion accident in the liquid sulfur tank, the flammability limit of hydrogen sulfide needs to be determined. Thus, it can be effectively monitored and targeted protective measures can be taken. The temperature of the gas phase space of the liquid sulfur tank exceeds 100 °C and sulfur vapor is present. In such a complex environment, there is no relevant study on the flammability limit of hydrogen sulfide. In this study, a system used to test the flammability limit of hydrogen sulfide in high temperature environment was established. In addition, the sulfur vapor environment can also be simulated. The experiments were carried out at temperature from 25 °C to 160 °C. The effect of temperature and sulfur vapor on the flammability limit of hydrogen sulfide was analyzed. The results showed that the upper flammability limit of hydrogen sulfide increases and the lower flammability limit decreases with the increase of the initial temperature. In addition, the effect of initial temperature on the flammability limit of hydrogen sulfide gradually diminishes in an exponential relationship. It was also found that the presence of sulfur vapor makes the flammability limit range of hydrogen sulfide narrower, but the effect is relatively weak. The results of this study can provide a basis for the detection of hydrogen sulfide concentration in the gas phase space of liquid sulfur tank, thus enhancing the safety of the production process.

Корозія бетону надводної частини нафтопастки в водному господарстві нафтовидобувного підприємства

The purpose of the work is to identify the type and kinetic indicators of concrete corrosion of the surface part of the oil trap in the water management of oil-and-gas facilities. Biogenic sulfuric acid concrete corrosion is a constant risk for water management facilities, in which hydrogen sulfide and its derivatives are present in the operating environment. Based on the analysis of the cycle of the oil production enterprise, the above processes are inherent in the water management of oil-and-gas facilities. The presence of hydrogen sulfide in water operating environments indicates a very high probability of the development of biogenic sulfuric acid aggression in the above-water moistened part of the structure - the influence of sulfuric acid produced by thion bacteria. An attractive environment for the accumulation of hydrogen sulfide by microbiological sulfate reduction is reservoir water at oil production sites, especially at water management sites where long-term sedimentation occurs. About 80% of losses from corrosion of oil industry equipment are associated with the activity of sulfate-reducing bacteria. In the experimental studies, concrete samples were studied, which were taken from the upper surface of the oil traps at the studied oil production facility located in the Dnipro-Donetsk depression. The results of a chemical study of concrete samples (decrease in pH, accumulation of sulfur compounds, and leaching of calcium compounds) indicated that the concrete is affected by biogenic sulfuric acid aggression. The experimentally determined dynamics of calcium compounds in the studied concrete samples indicated its leaching by aggressive sulfuric acid: the lower the pH of concrete, the lower the concentration of total calcium and the higher the concentration of mobile calcium. Based on data determined using a concrete corrosionmeter, the rate of microbiological corrosion of concrete was calculated - up to 0.08 mm/year, and the depth of diffusion of biogenic acids - up to 1.9 mm. The calculated average annual concentration of hydrogen sulfide in the atmosphere affecting concrete was 3.4 - 5.4 mg/m3, which exceeds the MPC of the working zone in the oil and gas industry.

Hydrogen sulfide suppresses the proliferation of intestinal epithelial cells through cell cycle arrest

The pathogenesis of chronic kidney disease (CKD) is closely related to the changes in the intestinal microbiota and integrity. Our previous studies have shown the accumulation of hydrogen sulfide (H2S)-producing bacterial family, Desulfovibrionacea, in the colon of a murine model of CKD, suggesting that the increased H2S contributes to the impaired intestinal integrity in CKD. Here, we investigated the anti-proliferative effect of H2S in the intestinal epithelial cells. A slow- H2S releasing molecule GYY4137 ((p-methoxyphenyl)morpholino-phosphinodithioic acid) reduced the proliferation of Caco-2 and IEC-6 cells. Flow cytometric analysis demonstrated that GYY4137 accumulated Caco-2 cells in the S phase fraction, suggesting that H2S arrested the cell cycle at G2 and/or M phases. The RNA sequencing analysis demonstrated that GYY4137 modulated the mRNA expression of the genes involved in the G2/M and the spindle assembly checkpoints; increased mRNA levels of Cdkn1a, Gadd45a, and Sfn and decreased mRNA levels of Cdc20, Pttg1, and Ccnb1 were observed. These alterations were confirmed by quantitative reverse transcription-polymerase chain reaction and Western blot analyses. Besides, studies exploring the MEK inhibitor indicated that MEK activation is involved in the GYY4137-mediated increase in the Sfn expression. Altogether, our data showed that H2S reduced the proliferation of intestinal epithelial cells through transcriptional regulation in G2/M and the spindle assembly checkpoints. This may be one of the underlying mechanisms for the observed impaired intestinal integrity in CKD.

Melatonin treatment delays senescence and improves antioxidant potential of sweet cherry fruits during cold storage

This study aimed to investigate the mechanisms activated by melatonin treatment at 0, 1, 10, 100, and 1000 µM for retarding senescence and improving the antioxidant potential of sweet cherry fruits during storage at 0 °C for 45 days. The results showed that sweet cherry fruits treated with 100 µM melatonin exhibited the lowest flesh browning and decay incidence after 45 days of storage at 0 °C. Moreover, endogenous melatonin accumulation occurring by higher tryptophan decarboxylase, tryptamine 5-hydroxylase, serotonin N-acetyltransferase, and N-acetylserotonin methyltransferase expression concomitant with endogenous hydrogen sulfide accumulation occurring by higher l-cysteine desulfhydrase and d-cysteine desulfhydrase expression and activity was promoted by melatonin in sweet cherry fruits. Besides, phenols, flavonoids, and anthocyanins accumulation and antioxidant potential were enhanced by melatonin in sweet cherry fruits via enhancing phenylalanine ammonia-lyase and chalcone synthase activities along with suppressing polyphenol oxidase activity. Interestingly, melatonin treatment maintained the membrane entirety in sweet cherry fruits, evaluated by malondialdehyde and hydrogen peroxide accumulation, which could be attributed to the enhanced activities of superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase enzymes while suppressed the activities of phospholipase D and lipoxygenase. Taken together, this study highlights the beneficial effects of melatonin in retarding senescence and improving the antioxidant potential of sweet cherry fruits during cold storage.

Sulfide catabolism ameliorates hypoxic brain injury

The mammalian brain is highly vulnerable to oxygen deprivation, yet the mechanism underlying the brain’s sensitivity to hypoxia is incompletely understood. Hypoxia induces accumulation of hydrogen sulfide, a gas that inhibits mitochondrial respiration. Here, we show that, in mice, rats, and naturally hypoxia-tolerant ground squirrels, the sensitivity of the brain to hypoxia is inversely related to the levels of sulfide:quinone oxidoreductase (SQOR) and the capacity to catabolize sulfide. Silencing SQOR increased the sensitivity of the brain to hypoxia, whereas neuron-specific SQOR expression prevented hypoxia-induced sulfide accumulation, bioenergetic failure, and ischemic brain injury. Excluding SQOR from mitochondria increased sensitivity to hypoxia not only in the brain but also in heart and liver. Pharmacological scavenging of sulfide maintained mitochondrial respiration in hypoxic neurons and made mice resistant to hypoxia. These results illuminate the critical role of sulfide catabolism in energy homeostasis during hypoxia and identify a therapeutic target for ischemic brain injury.

Delaying Broccoli Floret Yellowing by Phytosulfokine α Application During Cold Storage.

During postharvest life, broccoli suffers from floret yellowing confining its economic and nutritional value. The objective of the present study was to explore the mechanisms employed by phytosulfokine α (PSKα) at 150 nM for delaying floret yellowing in broccoli during storage at 4°C for 28 days. Our results showed that the higher endogenous accumulation of hydrogen sulfide (H2S) resulting from the higher gene expression and activities of l-cysteine desulfhydrase (LCD) and d-cysteine desulfhydrase (DCD) in broccoli floret treated with 150 nM PSKα may serve as an endogenous signaling molecule for delaying senescence. Moreover, the suppressed ethylene biosynthesis in broccoli floret treated with 150 nM PSKα might be ascribed to lower gene expression and activities of ACC synthase (ACS) and ACC oxidase (ACO). Furthermore, lower gene expression and activities of Mg2+ dechelatase (MDC), pheophytinase (PPH), and pheophorbide a oxygenase (PaO) might be the reasons for the higher accumulation of chlorophyll in broccoli floret treated with 150 nM PSKα. Based on our findings, exogenous PSKα application could be employed as signaling bioactive hormone for retarding floret yellowing of broccoli during storage at 4°C for 28 days.

A founder mutation in the ETHE1 gene and ethylmalonic encephalopathy in the Omani population

Background: Ethylmalonic encephalopathy (EE) is a devastating early-onset inborn error of metabolism, and heterogenous disorders manifest as chronic diarrhea, petechial rash, and neurological manifestations. The mutation in the ETHE1 gene leads to hydrogen sulfide accumulation and eventually results in mucosal cell damage in the large intestines and vascular endothelial cells system. Case presentation: Here, we describe four patients from three different tribes in Oman, and the clinical data revealed that the four patients shared an early-onset phenotype and the neurological manifestations were variable. The biochemical markers, specifically the urine organic acid and hyperlactimic acidosis, supported and tailored the diagnosis. Molecular diagnosis was confirmed by full gene sequencing of the ETHE1 gene in the index case and followed by target variant testing for others. Interestingly, all four patients identified to harbor the same homozygous missense pathogenic variant (c.487c > t) in the ETHE1 gene, and their parents were all heterozygous. These findings indicate that we probably have a founder variant associated with EE in our area. Conclusion: These findings are of great importance for diagnosis and surveillance for Omani families with EE. Given the relatively high number and frequency of genetic diseases in the region and the limited resources, screening for these founder mutations should provide a rapid and cost-effective tool for molecular diagnosis. Additionally, these findings should help in designing appropriate measures for carrier screening measures at the regional level.