The inhibition of mitochondrial cytochrome oxidase by the gases carbon monoxide, nitric oxide, hydrogen cyanide and hydrogen sulfide: chemical mechanism and physiological significance

Integrative analyses of convergent adaptation in sympatric extremophile fishes

The evolution of independent lineages along replicated environmental transitions frequently results in convergent adaptation, yet the degree to which convergence is present across multiple levels of biological organization is often unclear. Additionally, inherent biases associated with shared ancestry and variation in selective regimes across geographic replicates often pose challenges for confidently identifying patterns of convergence. We investigated a system in which three species of poeciliid fishes sympatrically occur in a toxic spring rich in hydrogen sulfide (H2S) and an adjacent nonsulfidic stream to examine patterns of adaptive evolution across levels of biological organization. We found convergence in morphological and physiological traits and genome-wide patterns of gene expression among all three species. In addition, there were shared signatures of selection on genes encoding H2S toxicity targets in the mitochondrial genomes of each species. However, analyses of nuclear genomes revealed neither evidence for substantial genomic islands of divergence around genes involved in H2S toxicity and detoxification nor substantial congruence of strongly differentiated regions across population pairs. These non-convergent, heterogeneous patterns of genomic divergence may indicate that sulfide tolerance is highly polygenic, with shared allele frequency shifts present at many loci with small effects along the genome. Alternatively, H2S tolerance may involve substantial genetic redundancy, with non-convergent, lineage-specific variation at multiple loci along the genome underpinning similar changes in phenotypes and gene expression. Overall, we demonstrate variability in the extent of convergence across organizational levels and highlight the challenges of linking patterns of convergence across scales.

Carbon monoxide supplementation: evaluating its potential to enhance altitude training effects and cycling performance in elite athletes

Altitude training is a cornerstone for endurance athletes for improving blood variables and performance, with optimal effects observed at ∼2,300-2,500 meters above sea level (m.a.s.l.). However, elite cyclists face challenges such as limited access to such altitudes, inadequate training facilities, and high expenses. To address these issues, a novel method involving daily exposure to carbon monoxide (CO) has been proposed to amplify altitude training adaptations at suboptimal altitudes. Thirty-one male cyclists were assigned to three groups: Live-High Train-High with CO inhalation (LHTHCO), Live-High Train-High (LHTH), and Live-Low Train-Low (LLTL). The LHTHCO group underwent CO inhalation twice daily in the afternoon/evening to elevate carboxyhemoglobin concentration to ∼10%. Hematological variables, in vivo muscle oxidative capacity, and physiological indicators of cycling performance were assessed before and after a 3-week altitude training camp at 2,100 m.a.s.l. LHTHCO demonstrated a larger increase in hemoglobin mass (Hbmass) compared to both LHTH and LLTL. Although there were no statistical differences between LHTHCO and LHTH in submaximal and maximal performance measures, LHTHCO displayed greater improvements in 1-min maximal power output during incremental testing (Wmax), power output at lactate threshold, and maximal oxygen consumption (V̇o2max) compared to LLTL. LHTH demonstrated a larger improvement than LLTL in Wmax and V̇o2max, with no group differences in Hbmass or submaximal measures. Muscle oxidative capacity did not differ between groups. These findings suggest that combining moderate-altitude training with daily CO inhalation promotes hematological adaptations more effectively than moderate altitude alone and enhances cycling performance metrics in cyclists more than sea-level training.NEW & NOTEWORTHY Three weeks of training at moderate altitude with exposure to low doses of CO can significantly enhance hematological adaptations in elite cyclists compared to moderate-altitude training alone. Cycling performance determinants improved more with CO inhalation at moderate altitude compared to sea-level training, whereas there were no differences in submaximal and maximal performance measures compared to moderate-altitude training alone. This study highlights the potential of CO supplementation as an effective adjunct to altitude training regimens.

A distinctive and proficient fluorescent switch for ratiometric recognition of the menacing cyanide ion: biological studies on MDA-MB-231 cells

A new fluorescent ratiometric switch (BOHB) was developed for swift and selective detection of cyanide ions in aqueous media without any interference from other competitive anions. Upon gradual addition of cyanide ions into the probe solution, a prominent fluorescence color change from yellow to cyan was observed under a UV chamber. The fluorescence changes thus observed were ratiometric, and the detection limit of this new probe was found to be (22.1 ± 0.89) μM, suggesting that the efficiency of BOHB for the detection of cyanide ions is brilliant even at a minute level. The blue shift in fluorescence intensity upon the addition of cyanide ions was attributed to the deprotonation mechanism of acidic protons present in BOHB. This phenomenon was further explored using 1H-NMR study, which supported the mechanism. Further, stability study was performed over a period of 5 days to prominently establish the stability of BOHB. The probe is also highly capable of recognizing CN- within a very short time-span (almost 15 seconds), thereby making it a brilliant fluorescent switch for the swift recognition of CN-. Furthermore, BOHB was employed for real water sample analysis to display its practical application. Besides, the easy-to-prepare dipstick experiment provides a simple, reusable and recyclable protocol for the suitable qualitative identification of CN-. Lastly, triple negative breast adenocarcinoma (MDA-MB-231) cells were made susceptible to CN- sensing in a biological system, thereby making BOHB a biomarker tool.

A Review of Recent Advances in Chromatographic Quantification Methods for Cyanogenic Glycosides

Cyanogenic glycosides are naturally occurring compounds found in numerous plant species, which can release toxic hydrogen cyanide upon hydrolysis. The quantification of cyanogenic glycosides is essential for assessing their potential toxicity and health risks associated with their consumption. Liquid chromatographic techniques coupled with various detectors have been widely used for the quantification of cyanogenic glycosides. In this review, we discuss recent advances in chromatographic quantification methods for cyanogenic glycosides, including the development of new stationary phases, innovative sample preparation methods, and the use of mass spectrometry. We also highlight the combination of chromatographic separation with mass spectrometric detection for the identification and quantification of specific cyanogenic glycosides and their metabolites in complex sample matrices. Lastly, we discuss the current challenges and future perspectives in the development of reliable reference standards, optimization of sample preparation methods, and establishment of robust quality control procedures. This review aims to provide an overview of recent advances in chromatographic quantification methods for cyanogenic glycosides and their applications in various matrices, including food products, biological fluids, and environmental samples.

Effects of L-NAME and air exposure on mitochondrial energetic markers, thyroid hormone receptor/regulator system and stress/ease-responsive receptor expression in the brain/gut axis of zebrafish

As a signal molecule, nitric oxide (NO) has several physiological actions in fish. However, the action of NO on the brain/gut axis, a classic inter-organal axis that bridges the gastrointestinal tract and the CNS, still requires more understanding. The short-term in vivo action of a NO inhibitor, N-omega-nitro-L-arginine methyl ester (L-NAME), on mitochondrial energetic markers and the receptor expression of thyroid hormone (TH) and neuroendocrine hormones involved in stress/ease response was tested in the brain/gut axis of zebrafish exposed to either in non-stressed or air-exposed condition. L-NAME treatment decreased the NO content in brain and gut segments in non-stressed fish but rose upon L-NAME treatment in air-exposed fish that corresponded with the activation of inos, nnos, hif1a and hif1an transcript expressions. The brain/gut segments that showed spatial and differential sensitivity to L-NAME, modified the transcript expression patterns of stress (adra2da, adrb1, nr3c2)- and ease-responsive (htr2b, slc6a4a, mtnr1aa) hormone receptors. The expression pattern of the TH receptor/regulator system (thra, thrb, dio1, dio2, dio3) becomes more active in gut segments than brain segments upon L-NAME challenge in stressed zebrafish. The data provide evidence for a novel role of NO as an integrator of brain/gut axis segments in zebrafish, where the endogenously produced NO in mid-brain/posterior-gut axis aligns together upon air-exposure stress, providing a lead role to the posterior gut that activates and directs the neuroendocrine receptor expressions of stress/ease responsive genes. The data further invites studies exploring the therapeutic potential of L-NAME in this biomedical model to control the brain/gut axis segments.

Role of hydrogen sulfide in health and disease

In the past, hydrogen sulfide (H2S) was recognized as a toxic and dangerous gas; in recent years, with increased research, we have discovered that H2S can act as an endogenous regulatory transmitter. In mammals, H2S-catalyzing enzymes, such as cystathionine-β-synthase, cystathionine-γ-lyase, and 3-mercaptopyruvate sulfurtransferase, are differentially expressed in a variety of tissues and affect a variety of biological functions, such as transcriptional and posttranslational modification of genes, activation of signaling pathways in the cell, and metabolic processes in tissues, by producing H2S. Various preclinical studies have shown that H2S affects physiological and pathological processes in the body. However, a detailed systematic summary of these roles in health and disease is lacking. Therefore, this review provides a thorough overview of the physiological roles of H2S in different systems and the diseases associated with disorders of H2S metabolism, such as ischemia-reperfusion injury, hypertension, neurodegenerative diseases, inflammatory bowel disease, and cancer. Meanwhile, this paper also introduces H2S donors and novel release modes, as well as the latest preclinical experimental results, aiming to provide researchers with new ideas to discover new diagnostic targets and therapeutic options.

Hydrogen sulfide maintains mitochondrial homeostasis and regulates ganoderic acids biosynthesis by SQR under heat stress in Ganoderma lucidum

Hydrogen sulfide (H2S) has recently been recognized as an important gaseous transmitter with multiple physiological effects in various species. Previous studies have shown that H2S alleviated heat-induced ganoderic acids (GAs) biosynthesis, an important quality index of Ganoderma lucidum. However, a comprehensive understanding of the physiological effects and molecular mechanisms of H2S in G. lucidum remains unexplored. In this study, we found that heat treatment reduced the mitochondrial membrane potential (MMP) and mitochondrial DNA copy number (mtDNAcn) in G. lucidum. Increasing the intracellular H2S concentration through pharmacological and genetic means increased the MMP level, mtDNAcn, oxygen consumption rate level and ATP content under heat treatment, suggesting a role for H2S in mitigating heat-caused mitochondrial damage in G. lucidum. Further results indicated that H2S activates sulfide-quinone oxidoreductase (SQR) and complex III (Com III), thereby maintaining mitochondrial homeostasis under heat stress in G. lucidum. Moreover, SQR also mediated the negative regulation of H2S to GAs biosynthesis under heat stress. Furthermore, SQR might be persulfidated under heat stress in G. lucidum. Thus, our study reveals a novel physiological function and molecular mechanism of H2S signalling under heat stress in G. lucidum with broad implications for research on the environmental response of microorganisms.

Beyond antibiotics: Emerging antivirulence strategies to combat Pseudomonas aeruginosa in cystic fibrosis

Pseudomonas aeruginosa is an opportunistic pathogen that poses a significant threat to individuals suffering from cystic fibrosis (CF). The pathogen is highly prevalent in CF individuals and is responsible for chronic infection, resulting in severe tissue damage and poor patient outcome. Prolonged antibiotic administration has led to the emergence of multidrug resistance in P. aeruginosa. In this direction, antivirulence strategies achieving targeted inhibition of bacterial virulence pathways, including quorum sensing, efflux pumps, lectins, and iron chelators, have been explored against CF isolates of P. aeruginosa. Hence, this review article presents a bird's eye view on the pulmonary infections involving P. aeruginosa in CF patients by laying emphasis on factors contributing to bacterial colonization, persistence, and disease progression along with the current line of therapeutics against P. aeruginosa in CF. We further collate scientific literature and discusses various antivirulence strategies that have been tested against P. aeruginosa isolates from CF patients.

Mucosal organs exhibit distinct response signatures to hydrogen sulphide in Atlantic salmon (Salmo salar)

Hydrogen sulphide (H2S) is considered an immunotoxicant, and its presence in the water can influence the mucosal barrier functions of fish. However, there is a significant knowledge gap on how fish mucosa responds to low environmental H2S levels. The present study investigated the consequences of prolonged exposure to sub-lethal levels of H2S on the mucosal defences of Atlantic salmon (Salmo salar). Fish were continuously exposed to two levels of H2S (low: 0.05 µM; and high: 0.12 µM) for 12 days. Unexposed fish served as control. Molecular and histological profiling focused on the changes in the skin, gills and olfactory rosette. In addition, metabolomics and proteomics were performed on the skin and gill mucus. The gene expression profile indicated that the gills and olfactory rosette were more sensitive to H2S than the skin. The olfactory rosette showed a dose-dependent response, but not the gills. Genes related to stress responses were triggered at mucosal sites by H2S. Moreover, H2S elicited strong inflammatory responses, particularly in the gills. All mucosal organs demonstrated the key molecular repertoire for sulphide detoxification, but their temporal and spatial expression was not substantially affected by sub-lethal H2S levels. Mucosal barrier integrity was not considerably affected by H2S. Mucus metabolomes of the skin and gills were unaffected, but a matrix-dependent response was identified. Comparing the high-concentration group's skin and gills mucus metabolomes identified altered amino acid biosynthesis and metabolism pathways. The skin and gill mucus exhibited distinct proteomic profiles. Enrichment analysis revealed that proteins related to immunity and metabolism were affected in both mucus matrices. The present study expands our knowledge of the defence mechanisms against H2S at mucosal sites in Atlantic salmon. The findings offer insights into the health and welfare consequences of sub-lethal H2S, which can be incorporated into the risk assessment protocols in salmon land-based farms.

Carbon Monoxide as a Potential Therapeutic Agent: A Molecular Analysis of Its Safety Profiles

Carbon monoxide (CO) is endogenously produced in mammals, with blood concentrations in the high micromolar range in the hemoglobin-bound form. Further, CO has shown therapeutic effects in various animal models. Despite its reputation as a poisonous gas at high concentrations, we show that CO should have a wide enough safety margin for therapeutic applications. The analysis considers a large number of factors including levels of endogenous CO, its safety margin in comparison to commonly encountered biomolecules or drugs, anticipated enhanced safety profiles when delivered via a noninhalation mode, and the large amount of safety data from human clinical trials. It should be emphasized that having a wide enough safety margin for therapeutic use does not mean that it is benign or safe to the general public, even at low doses. We defer the latter to public health experts. Importantly, this Perspective is written for drug discovery professionals and not the general public.

Lactoperoxidase catalytically oxidize hydrogen sulfide via intermediate formation of sulfheme derivatives

The biological chemistry of hydrogen sulfide (H2S) with physiologically important heme proteins is in the focus of redox biology research. In this study, we investigated the interactions of lactoperoxidase (LPO) with H2S in the presence and absence of molecular dioxygen (O2) or hydrogen peroxide (H2O2). Under anaerobic conditions, native LPO forms no heme-H2S complex upon sulfide exposure. However, under aerobic conditions or in the presence of H2O2 the formation of both ferrous and ferric sulfheme (sulfLPO) derivatives was observed based on the appearances of their characteristic optical absorptions at 638 nm and 727 nm, respectively. Interestingly, we demonstrate that LPO can catalytically oxidize H2S by H2O2 via intermediate formation of relatively short-lived ferrous and ferric sulfLPO derivatives. Pilot product analyses suggested that the turnover process generates oxidized sulfide species, which include sulfateS O 4 2 - and inorganic polysulfides (H S x - ; x = 2-5). These results indicated that H2S can serve as a non-classical LPO substrate by inducing a reversible sulfheme-like modification of the heme porphyrin ring during turnover. Furthermore, electron paramagnetic resonance data suggest that H2S can act as a scavenger of H2O2 in the presence of LPO without detectable formation of any carbon-centered protein radical species, suggesting that H2S might be capable of protecting the enzyme from radical-mediated damage. We propose possible mechanisms, which explain our results as well as contrasting observations with other heme proteins, where either no sulfheme formation was observed or the generation of sulfheme derivatives provided a dead end for enzyme functions.

Membrane-Bound Ferric Hemoglobin in Nucleated Erythrocytes of the Black Scorpionfish Scorpaena porcus, Linnaeus 1758

The content of membrane-bound methemoglobin (MtHb) in nucleated erythrocytes was studied in the black scorpionfish Scorpaena porcus (Linnaeus, 1758) in vitro. Spectral characteristics were determined for a whole hemolysate, a hemolysate obtained by stroma precipitation (a clarified hemolysate), and a resuspended stroma. The MtHb proportion in the erythrocyte stroma was found to exceed 80% (6.20 ± 0.59 µM). Clarified hemolysates were nearly free of MtHb (0.5 ± 0.2 µM). Membrane-bound ferric hemoglobin did not affect the erythrocyte resistance to osmotic shock. The osmotic fragility range was determined using a LaSca-TM laser microparticle analyzer (BioMedSystems, Russia) to be 102-136 mOsm/kg, much the same as in other bony fish species. A nitrite load (10 mg/L) significantly increased the MtHb content in the blood. However, the membrane-bound ferric hemoglobin content did not change significantly, amounting to 6.34 ± 1.09 µM (approximately 95%). The finding suggested a functional importance for MtHb present in the plasma membrane of nucleated erythrocytes. Membrane-bound MtHb was assumed to neutralize the external oxidative load and the toxic effect of hydrogen sulfide in bottom water layers, where the species lives.

Role of the 3-mercaptopyruvate sulfurtransferase in colon/colorectal cancers

The 3-mercaptopyruvate sulfurtransferase (MPST) is a protein persulfidase, occurring mainly in mitochondria. Although function of this protein in cancer cells has been already studied, no clear outcome can be postulated up to now. Therefore, we focused on the determination of function of MPST in colon (HCT116 cells)/colorectal (DLD1 cells) cancers. In silico analysis revealed that in gastrointestinal cancers, MPST together with its binding partners can be either of a high risk or might have a protective effect. Silencing of MPST gene resulted in decreased ATP, while acetyl-CoA levels were elevated. Increased apoptosis was detected in cells with silenced MPST gene, which was accompanied by decrease in mitochondrial membrane potential, but no changes in IP3 receptor's protein. Mitochondria underwent activation of fission and elevated DRP1 expression after MPST silencing. Proliferation and migration of DLD1 and HCT116 cells were markedly affected, showing the importance of MPST protein in colon/colorectal cancer development.

Nonheme binuclear transition metal complexes with hydrosulfide and polychalcogenides

The intriguing chemistry of chalcogen (S, Se)-containing ligands and their capability to bridge multiple metal centres have resulted in a plethora of reports on transition metal complexes featuring hydrosulfide (HS-) and polychalcogenides (En2-, E = S, Se). While a large number of such molecules are strictly organometallic complexes, examples of non-organometallic complexes featuring HS- and En2- with N-/O-donor ligands are relatively rare. The general synthetic procedure for the transition metal-hydrosulfido complexes involves the reaction of the corresponding metal salts with HS-/H2S and this is prone to generate sulfido bridged oligomers in the absence of sterically demanding ligands. On the other hand, the synthetic methods for the preparation of transition metal-polychalcogenido complexes include the reaction of the corresponding metal salts with En2- or the two electron oxidation of low-valent metals with elemental chalcogen, often at an elevated temperature and/or for a long time. Recently, we have developed new synthetic methods for the preparation of two new classes of binuclear transition metal complexes featuring either HS-, or Sn2- and Sen2- ligands. The new method for the synthesis of transition metal-hydrosulfido complexes involved transition metal-mediated hydrolysis of thiolates at room temperature (RT), while the method for the synthesis of transition metal-polychalcogenido complexes involved redox reaction of coordinated thiolates and exogenous elemental chalcogens at RT. An overview of the synthetic aspects, structural properties and intriguing reactivity of these two new classes of transition metal complexes is presented.

Dual-Modality Imaging-Guided Manganese-Based Nanotransformer for Enhanced Gas-Photothermal Therapy Combined Immunotherapeutic Strategy Against Triple-Negative Breast Cancer

Activating the stimulator of the interferon gene (STING) is a promising immunotherapeutic strategy for converting "cold" tumor microenvironment into "hot" one to achieve better immunotherapy for malignant tumors. Herein, a manganese-based nanotransformer is presented, consisting of manganese carbonyl and cyanine dye, for MRI/NIR-II dual-modality imaging-guided multifunctional carbon monoxide (CO) gas treatment and photothermal therapy, along with triggering cGAS-STING immune pathway against triple-negative breast cancer. This nanosystem is able to transfer its amorphous morphology into a crystallographic-like formation in response to the tumor microenvironment, achieved by breaking metal-carbon bonds and forming coordination bonds, which enhances the sensitivity of magnetic resonance imaging. Moreover, the generated CO and photothermal effect under irradiation of this nanotransformer induce immunogenic death of tumor cells and release damage-associated molecular patterns. Simultaneously, the Mn acts as an immunoactivator, potentially stimulating the cGAS-STING pathway to augment adaptive immunity, resulting in promoting the secretion of type I interferon, the proliferation of cytotoxic T lymphocytes and M2-macrophages repolarization. This nanosystem-based gas-photothermal treatment and immunoactivating therapy synergistic effect exhibit excellent antitumor efficacy both in vitro and in vivo, reducing the risk of triple-negative breast cancer recurrence and metastasis; thus, this strategy presents great potential as multifunctional immunotherapeutic agents for cancer treatment.

Rapid HPLC method reveals dynamic shifts in coenzyme Q redox state

Ubiquinol or coenzyme Q (CoQ) is a lipid-soluble electron carrier in the respiratory chain and an electron acceptor for various enzymes in metabolic pathways that intersect at this cofactor hub in the mitochondrial inner membrane. The reduced form of CoQ is an antioxidant, which protects against lipid peroxidation. In this study, we have optimized a UV-detected HPLC method for CoQ analysis from biological materials, which involves a rapid single-step extraction into n-propanol followed by direct sample injection onto a column. Using this method, we have measured the oxidized, reduced, and total CoQ pools and monitored shifts in the CoQ redox status in response to cell culture conditions and bioenergetic perturbations. We find that hypoxia or sulfide exposure induces a reductive shift in the intracellular CoQ pool. The effect of hypoxia is, however, rapidly reversed by exposure to ambient air. Interventions at different loci in the electron transport chain can induce sizeable redox shifts in the oxidative or reductive direction, depending on whether they are up- or downstream of complex III. We have also used this method to confirm that CoQ levels are higher and more reduced in murine heart versus brain. In summary, the availability of a convenient HPLC-based method described herein will facilitate studies on CoQ redox dynamics in response to environmental, nutritional, and endogenous alterations.

Mefloquine-curcumin combinations improve host mitochondrial respiration and decrease mitotoxic effects of mefloquine in Plasmodium berghei-infected mice

Plasmodium infection is a health challenge. Although, antiplasmodial drugs kill the parasites, information on the effects of infection and drugs on the expression of some genes is limited. Malaria was induced in two different studies using NK65 (chloroquine-susceptible, study 1), and ANKA (chloroquine-resistant, study 2) strains of Plasmodium berghei in 30 male Swiss mice (n = 5) in each study. Mice orally received 10 mL/kg distilled water, (infected control), Mefloquine (MF) (10 mg/kg), MF and Curcumin (CM) (25 mg/kg), MF and CM (50 mg/kg), CM (25 mg/kg) and CM (50 mg/kg). Five mice (un-infected) were used as the control. After treatment, total Ribonucleic acid (RNA) was isolated from liver and erythrocytes while Deoxyribonucleic acid (DNA)-free RNA were converted to cDNA. Polymerase Chain Reaction (PCR) amplification was performed and relative expressions of FIKK12, AQP3, P38 MAPK, NADH oxidoreductase, and cytochrome oxidase expressions were determined. Markers of glycolysis, toxicity and antioxidants were determined using ELISA assays. While the expression of FIKK12 was blunted by MF in the susceptible study, co-treatment with curcumin (25 mg/kg) yielded the same results in the chloroquine-resistant study. Similar results were obtained on AQP3 in both studies. Curcumin decreased P38 MAPK in both studies. Plasmodium infection decreased NADH oxidoreductase and cytochrome oxidase but mefloquine-curcumin restored the expression of these genes. While glycolysis and toxicity were inhibited, antioxidant systems improved in the treated groups. Curcumin is needed for effective therapeutic efficacy and prevention of toxicity. Plasmodium infection and treatment modulate the expressions of some genes in the host. Curcumin combination with mefloquine modulates the expression of some genes in the host.

H2S preconditioning induces long-lived perturbations in O2 metabolism

Hydrogen sulfide exposure in moderate doses can induce profound but reversible hypometabolism in mammals. At a cellular level, H2S inhibits the electron transport chain (ETC), augments aerobic glycolysis, and glutamine-dependent carbon utilization via reductive carboxylation; however, the durability of these changes is unknown. We report that despite its volatility, H2S preconditioning increases P50(O2), the O2 pressure for half-maximal cellular respiration, and has pleiotropic effects on oxidative metabolism that persist up to 24 to 48 h later. Notably, cyanide, another complex IV inhibitor, does not induce this type of metabolic memory. Sulfide-mediated prolonged fractional inhibition of complex IV by H2S is modulated by sulfide quinone oxidoreductase, which commits sulfide to oxidative catabolism. Since induced hypometabolism can be beneficial in disease settings that involve insufficient or interrupted blood flow, our study has important implications for attenuating reperfusion-induced ischemic injury and/or prolonging the shelf life of biologics like platelets.

Effect of reactive oxygen, nitrogen, and sulfur species on signaling pathways in atherosclerosis

Atherosclerosis is a chronic inflammatory disease in which fats, lipids, cholesterol, calcium, proliferating smooth muscle cells, and immune cells accumulate in the intima of the large arteries, forming atherosclerotic plaques. A complex interplay of various vascular and immune cells takes place during the initiation and progression of atherosclerosis. Multiple reports indicate that tight control of reactive oxygen species (ROS), reactive nitrogen species (RNS), and reactive sulfur species (RSS) production is critical for maintaining vascular health. Unrestricted ROS and RNS generation may lead to activation of various inflammatory signaling pathways, facilitating atherosclerosis. Given these deleterious consequences, it is important to understand how ROS and RNS affect the signaling processes involved in atherogenesis. Conversely, RSS appears to exhibit an atheroprotective potential and can alleviate the deleterious effects of ROS and RNS. Herein, we review the literature describing the effects of ROS, RNS, and RSS on vascular smooth muscle cells, endothelial cells, and macrophages and focus on how changes in their production affect the initiation and progression of atherosclerosis. This review also discusses the contribution of ROS, RNS, and RSS in mediating various post-translational modifications, such as oxidation, nitrosylation, and sulfation, of the molecules involved in inflammatory signaling.

Hydrogen sulfide responsive nanoplatforms: Novel gas responsive drug delivery carriers for biomedical applications

Hydrogen sulfide (H2S) is a toxic, essential gas used in various biological and physical processes and has been the subject of many targeted studies on its role as a new gas transmitter. These studies have mainly focused on the production and pharmacological side effects caused by H2S. Therefore, effective strategies to remove H2S has become a key research topic. Furthermore, the development of novel nanoplatforms has provided new tools for the targeted removal of H2S. This paper was performed to review the association between H2S and disease, related H2S inhibitory drugs, as well as H2S responsive nanoplatforms (HRNs). This review first analyzed the role of H2S in multiple tissues and conditions. Second, common drugs used to eliminate H2S, as well as their potential for combination with anticancer agents, were summarized. Not only the existing studies on HRNs, but also the inhibition H2S combined with different therapeutic methods were both sorted out in this review. Furthermore, this review provided in-depth analysis of the potential of HRNs about treatment or detection in detail. Finally, potential challenges of HRNs were proposed. This study demonstrates the excellent potential of HRNs for biomedical applications.

Fluorescence-based ratiometric sensors as emerging tools for CN- detection: Chemical structures, sensing mechanisms and applications

Hazardous cyanide anions (CN-) are increasingly threatening the environment and human health due to their widespread use in industry and many other fields. Over the past three decades, a large number of probes have been reported to sensitively and selectively detect this toxic anion, while a rather limited number of ratiometric fluorescent probes have been developed. The ratiometric probes have significant potential in bio-imaging and biomedical applications because of the ability to detect CN- in a quick, convenient and affordable way. In this review, we introduce 42 ratiometric fluorescent probes reported in the past 6 years (2018-2023) for CN- detection. Our description includes the chemical structures, photo-physical properties, CN- sensing mechanisms, solution color changes, limits of detection (LODs) and/or various applications of these chemical probes. This review provides guidelines for design and development of a new ratiometric probe for effective CN- detection.

MpaR-driven expression of an orphan terminal oxidase subunit supports Pseudomonas aeruginosa biofilm respiration and development during cyanogenesis

IMPORTANCE

Cyanide is an inhibitor of heme-copper oxidases, which are required for aerobic respiration in all eukaryotes and many prokaryotes. This fast-acting poison can arise from diverse sources, but mechanisms by which bacteria sense it are poorly understood. We investigated the regulatory response to cyanide in the pathogenic bacterium Pseudomonas aeruginosa, which produces cyanide as a virulence factor. Although P. aeruginosa has the capacity to produce a cyanide-resistant oxidase, it relies primarily on heme-copper oxidases and even makes additional heme-copper oxidase proteins specifically under cyanide-producing conditions. We found that the protein MpaR controls expression of cyanide-inducible genes in P. aeruginosa and elucidated the molecular details of this regulation. MpaR contains a DNA-binding domain and a domain predicted to bind pyridoxal phosphate (vitamin B6), a compound that is known to react spontaneously with cyanide. These observations provide insight into the understudied phenomenon of cyanide-dependent regulation of gene expression in bacteria.

Recent advances in pyroptosis, liver disease, and traditional Chinese medicine: A review

In recent years, the incidence of liver disease has increased, becoming a major cause of death. Various liver diseases are intricately linked to pyroptosis, which is one of the most common forms of programmed cell death. As a powerful weapon in the fight against liver diseases, traditional Chinese medicine (TCM) can affect pyroptosis via a number of routes, including the classical, nucleotide oligomerization domain-like receptors protein 3/caspase-1/gasdermin D (GSDMD) pathway, the nonclassical lipopolysaccharide/caspase-11/GSDMD pathway, the ROS/caspase-3/gasdermin E pathway, the caspase-9/caspase-3/GSDMD pathway, and the Apaf-1/caspase-11/caspase-3 pathway. In this review, we provide an overview of pyroptosis, the interplay between pyroptosis and liver diseases, and the mechanisms through which TCM regulates pyroptosis in liver diseases. The information used in the text was collected and compiled from the databases of PubMed, Web of Science, Scopus, CNKI, and Wanfang Data up to June 2023. The search was not limited with regard to the language and country of the articles. Research and review articles were included, and papers with duplicate results or unrelated content were excluded. We examined the current understanding of the relationship between pyroptosis and liver diseases as well as the advances in TCM interventions to provide a resource for the identification of potential targets for TCM in the treatment of liver diseases.

Chromosome-level genome assembly of the deep-sea snail Phymorhynchus buccinoides provides insights into the adaptation to the cold seep habitat

BACKGROUND

The deep-sea snail Phymorhynchus buccinoides belongs to the genus Phymorhynchus (Neogastropoda: Raphitomidae), and it is a dominant specie in the cold seep habitat. As the environment of the cold seep is characterized by darkness, hypoxia and high concentrations of toxic substances such as hydrogen sulfide (H2S), exploration of the diverse fauna living around cold seeps will help to uncover the adaptive mechanisms to this unique habitat. In the present study, a chromosome-level genome of P. buccinoides was constructed and a series of genomic and transcriptomic analyses were conducted to explore its molecular adaptation mechanisms to the cold seep environments.

RESULTS

The assembled genome size of the P. buccinoides was approximately 2.1 Gb, which is larger than most of the reported snail genomes, possibly due to the high proportion of repetitive elements. About 92.0% of the assembled base pairs of contigs were anchored to 34 pseudo-chromosomes with a scaffold N50 size of 60.0 Mb. Compared with relative specie in the shallow water, the glutamate regulative and related genes were expanded in P. buccinoides, which contributes to the acclimation to hypoxia and coldness. Besides, the relatively high mRNA expression levels of the olfactory/chemosensory genes in osphradium indicate that P. buccinoides might have evolved a highly developed and sensitive olfactory organ for its orientation and predation. Moreover, the genome and transcriptome analyses demonstrate that P. buccinoides has evolved a sulfite-tolerance mechanism by performing H2S detoxification. Many genes involved in H2S detoxification were highly expressed in ctenidium and hepatopancreas, suggesting that these tissues might be critical for H2S detoxification and sulfite tolerance.

CONCLUSIONS

In summary, our report of this chromosome-level deep-sea snail genome provides a comprehensive genomic basis for the understanding of the adaptation strategy of P. buccinoides to the extreme environment at the deep-sea cold seeps.

A bacterial pathogen induces developmental slowing by high reactive oxygen species and mitochondrial dysfunction in Caenorhabditis elegans

Host-pathogen interactions are complex by nature, and the host developmental stage increases this complexity. By utilizing Caenorhabditis elegans larvae as the host and the bacterium Pseudomonas aeruginosa as the pathogen, we investigated how a developing organism copes with pathogenic stress. By screening 36 P. aeruginosa isolates, we found that the CF18 strain causes a severe but reversible developmental delay via induction of reactive oxygen species (ROS) and mitochondrial dysfunction. While the larvae upregulate mitophagy, antimicrobial, and detoxification genes, mitochondrial unfolded protein response (UPRmt) genes are repressed. Either antioxidant or iron supplementation rescues the phenotypes. We examined the virulence factors of CF18 via transposon mutagenesis and RNA sequencing (RNA-seq). We found that non-phenazine toxins that are regulated by quorum sensing (QS) and the GacA/S system are responsible for developmental slowing. This study highlights the importance of ROS levels and mitochondrial health as determinants of developmental rate and how pathogens can attack these important features.

H 2 S preconditioning induces long-lived perturbations in O 2 metabolism

Hydrogen sulfide exposure in moderate doses can induce profound but reversible hypometabolism in mammals. At a cellular level, H 2 S inhibits the electron transport chain (ETC), augments aerobic glycolysis, and glutamine-dependent carbon utilization via reductive carboxylation; however, the durability of these changes is unknown. We report that despite its volatility, H 2 S preconditioning increases P 50(O2) , the O 2 pressure for half maximal cellular respiration, and has pleiotropic effects on oxidative metabolism that persist up to 24-48 h later. Notably, cyanide, another complex IV inhibitor, does not induce this type of metabolic memory. Sulfide-mediated prolonged fractional inhibition of complex IV by H 2 S is modulated by sulfide quinone oxidoreductase, which commits sulfide to oxidative catabolism. Since induced hypometabolism can be beneficial in disease settings that involve insufficient or interrupted blood flow, our study has important implications for attenuating reperfusion-induced ischemic injury, and/or prolonging shelf life of biologics like platelets.

Role of Hydrogen Sulfide in Inflammatory Bowel Disease

Hydrogen sulfide (H2S), originally known as toxic gas, has now attracted attention as one of the gasotransmitters involved in many reactions in the human body. H2S has been assumed to play a role in the pathogenesis of many chronic diseases, of which the exact pathogenesis remains unknown. One of them is inflammatory bowel disease (IBD), a chronic intestinal disease subclassified as Crohn's disease (CD) and ulcerative colitis (UC). Any change in the amount of H2S seems to be linked to inflammation in this illness. These changes can be brought about by alterations in the microbiota, in the endogenous metabolism of H2S and in the diet. As both too little and too much H2S drive inflammation, a balanced level is needed for intestinal health. The aim of this review is to summarize the available literature published until June 2023 in order to provide an overview of the current knowledge of the connection between H2S and IBD.

Clinical Applications for Gasotransmitters in the Cardiovascular System: Are We There Yet?

Ischemia is the underlying mechanism in a wide variety of acute and persistent pathologies. As such, understanding the fine intracellular events occurring during (and after) the restriction of blood supply is pivotal to improving the outcomes in clinical settings. Among others, gaseous signaling molecules constitutively produced by mammalian cells (gasotransmitters) have been shown to be of potential interest for clinical treatment of ischemia/reperfusion injury. Nitric oxide (NO and its sibling, HNO), hydrogen sulfide (H2S), and carbon monoxide (CO) have long been proven to be cytoprotective in basic science experiments, and they are now awaiting confirmation with clinical trials. The aim of this work is to review the literature and the clinical trials database to address the state of development of potential therapeutic applications for NO, H2S, and CO and the clinical scenarios where they are more promising.

Ratiometric orange fluorescent and colorimetric highly sensitive imidazolium-bearing naphthoquinolinedione-based probes for CN- sensing in aqueous solutions and bio-samples

The widespread use of cyanide (CN^-) in industry results in contamination of various effluents such as drain, lake, and tap water, an imminent danger to the environment and human health. We prepared naphthoquinolinedione (cyclized; 1-5) and anthracenedione (un-cyclized) probes (6-7) for selective detection of CN^-. The addition of CN^- to the probe solutions (1-5) resulted in a color change from pale green to orange under 365 nm illumination. The nucleophilic addition of CN^- to C2 of the imidazolium ring of the probes is responsible for selective CN^- detection. Among all probes, 1 gave the lowest fluorescence-based LOD of 0.13 pM. In contrast, the un-cyclized probes (6 and 7) were substantially inferior to the cyclized counterparts (1 and 2, respectively) for detecting a trace amount of CN^-. The notably low LOD displayed by probe 1 was maintained in the detection of CN^- in real food samples, human fluids, and human brain cells. This is the first report studying imidazolium-bearing naphthoquinolinedione-based probes for CN^- sensing in 100% water.

Simultaneous determination of cyanide and thiocyanate in milk by GC-MS/MS using cetyltrimethylammonium bromide as both phase transfer catalyst and protein precipitant

A method was developed for simultaneous determination of cyanide and thiocyanate in milk by gas chromatography-tandem quadrupole mass spectrometry (GC-MS/MS). Cyanide and thiocyanate were derivatized with pentafluorobenzyl bromide (PFBBr) as PFB-CN and PFB-SCN, respectively. Cetyltrimethylammonium bromide (CTAB) was employed both as a phase transfer catalyst and a protein precipitant in the sample pretreatment, which facilitates the separation of the organic and aqueous phases, and greatly simplifies the pretreatment procedures to achieve simultaneous and rapid determination of cyanide and thiocyanate. Under the optimized conditions, the limits of detection (LODs) of cyanide and thiocyanate in milk were 0.006 mg/kg and 0.015 mg/kg, and the spiked recoveries ranged from 90.1% to 98.2% and from 91.8% to 98.9% with relative standard deviations (RSDs) less than 18.9% and 15.2%, respectively. The proposed method was validated as a simple, fast and highly sensitive method for the determination of cyanide and thiocyanate in milk.

Computational Analysis Reveals Unique Binding Patterns of Oxygenated and Deoxygenated Myoglobin to the Outer Mitochondrial Membrane

Myoglobin (Mb) interaction with the outer mitochondrial membrane (OMM) promotes oxygen (O₂) release. However, comprehensive molecular details on specific contact regions of the OMM with oxygenated (oxy-) and deoxygenated (deoxy-)Mb are missing. We used molecular dynamics (MD) simulations to explore the interaction of oxy- and deoxy-Mb with the membrane lipids of the OMM in two lipid compositions: (a) a typical whole membrane on average, and (b) specifically the cardiolipin-enriched cristae region (contact site). Unrestrained relaxations showed that on average, both the oxy- and deoxy-Mb established more stable contacts with the lipids typical of the cristae contact site, then with those of the average OMM. However, in steered detachment simulations, deoxy-Mb clung more tightly to the average OMM, and oxy-Mb strongly preferred the contact sites of the OMM. The MD simulation analysis further indicated that a non-specific binding, mediated by local electrostatic interactions, existed between charged or polar groups of Mb and the membrane, for stable interaction. To the best of our knowledge, this is the first computational study providing the molecular details of the direct Mb-mitochondria interaction that assisted in distinguishing the preferred localization of oxy- and deoxy-Mb on the OMM. Our findings support the existing experimental evidence on Mb-mitochondrial association and shed more insights on Mb-mediated O₂ transport for cellular bioenergetics.

Awareness raising and dealing with methanol poisoning based on effective strategies

Intoxication with methanol most commonly occurs as a consequence of ingesting, inhaling, or coming into contact with formulations that include methanol as a base. Clinical manifestations of methanol poisoning include suppression of the central nervous system, gastrointestinal symptoms, and decompensated metabolic acidosis, which is associated with impaired vision and either early or late blindness within 0.5-4 h after ingestion. After ingestion, methanol concentrations in the blood that are greater than 50 mg/dl should raise some concern. Ingested methanol is typically digested by alcohol dehydrogenase (ADH), and it is subsequently redistributed to the body's water to attain a volume distribution that is about equivalent to 0.77 L/kg. Moreover, it is removed from the body as its natural, unchanged parent molecules. Due to the fact that methanol poisoning is relatively uncommon but frequently involves a large number of victims at the same time, this type of incident occupies a special position in the field of clinical toxicology. The beginning of the COVID-19 pandemic has resulted in an increase in erroneous assumptions regarding the preventative capability of methanol in comparison to viral infection. More than 1000 Iranians fell ill, and more than 300 of them passed away in March of this year after they consumed methanol in the expectation that it would protect them from a new coronavirus. The Atlanta epidemic, which involved 323 individuals and resulted in the deaths of 41, is one example of mass poisoning. Another example is the Kristiansand outbreak, which involved 70 people and resulted in the deaths of three. In 2003, the AAPCC received reports of more than one thousand pediatric exposures. Since methanol poisoning is associated with high mortality rates, it is vital that the condition be addressed seriously and managed as quickly as feasible. The objective of this review was to raise awareness about the mechanism and metabolism of methanol toxicity, the introduction of therapeutic interventions such as gastrointestinal decontamination and methanol metabolism inhibition, the correction of metabolic disturbances, and the establishment of novel diagnostic/screening nanoparticle-based strategies for methanol poisoning such as the discovery of ADH inhibitors as well as the detection of the adulteration of alcoholic drinks by nanoparticles in order to prevent methanol poisoning. In conclusion, increasing warnings and knowledge about clinical manifestations, medical interventions, and novel strategies for methanol poisoning probably results in a decrease in the death load.

Acute Cardiomyopathy and Delayed Neuropsychiatric Sequelae of Carbon Monoxide Poisoning: A Case Report

Carbon monoxide (CO) is an odorless and colorless gas that is formed by the combustion of hydrocarbon. CO poisoning is not an uncommon phenomenon that can have serious consequences for morbidity and mortality. The most frequent causes of accidental poisoning include smoke inhalation from fires, malfunctioning heating devices, smoke from motor vehicles in a poorly ventilated or enclosed space, and electrical cable fires. CO has a higher affinity to hemoglobin than oxygen leading to the formation of carboxyhemoglobin. It impairs the oxygen transport and cytochrome chain which, therefore, leads to further cellular and immunological changes. Here, we present a case of CO poisoning resulting in combined cardiac and neuropsychiatric complications.

Cyanide-dependent control of terminal oxidase hybridization by Pseudomonas aeruginosa MpaR

Pseudomonas aeruginosa is a common, biofilm-forming pathogen that exhibits complex pathways of redox metabolism. It produces four different types of terminal oxidases for aerobic respiration, and for one of these-the cbb3-type terminal oxidases-it has the capacity to produce at least 16 isoforms encoded by partially redundant operons. It also produces small-molecule virulence factors that interact with the respiratory chain, including the poison cyanide. Previous studies had indicated a role for cyanide in activating expression of an "orphan" terminal oxidase subunit gene called ccoN4 and that the product contributes to P. aeruginosa cyanide resistance, fitness in biofilms, and virulence-but the mechanisms underlying this process had not been elucidated. Here, we show that the regulatory protein MpaR, which is predicted to be a pyridoxal phosphate-binding transcription factor and is encoded just upstream of ccoN4, controls ccoN4 expression in response to endogenous cyanide. Paradoxically, we find that cyanide production is required to support CcoN4's contribution to respiration in biofilms. We identify a palindromic motif required for cyanide- and MpaR-dependent expression of ccoN4 and co-expressed, adjacent loci. We also characterize the regulatory logic of this region of the chromosome. Finally, we identify residues in the putative cofactor-binding pocket of MpaR that are required for ccoN4 expression. Together, our findings illustrate a novel scenario in which the respiratory toxin cyanide acts as a signal to control gene expression in a bacterium that produces the compound endogenously.

The chemistry of hydropersulfides (RSSH) as related to possible physiological functions

Hydropersulfides (RSSH) are oxidized thiol (RSH) derivatives that have been shown to be biologically prevalent with likely important functions (along with other polysulfur compounds). The functional utility of RSSH can be gleaned from their unique chemical properties. That is, RSSH possess chemical reactivity not present in other biologically relevant sulfur species that should allow them to be used in specific ways in biology as effector/signaling molecules. For example, compared to RSH, RSSH are considered to be superior nucleophiles, reductants and metal ligands. Moreover, unlike RSH, RSSH can be either reductants/nucleophiles or oxidants/electrophiles depending on the protonated state. It has also become clear that studies related to the chemical biology and physiology of hydrogen suflide (H₂S) must also consider the effects of RSSH (and related polysulfur species) as they are biochemically linked. Herein is a discussion of the relevant chemistry of RSSH that can serve as a basis for understanding how RSSH can be used by cells to, for example, combat stresses and used in signaling. Also, discussed are some current experimental studies regarding the biological activity of RSSH that can be explained by their chemical properties.

Regulation of enteroendocrine cell respiration by the microbial metabolite hydrogen sulfide

Endocrine functions of the gut are supported by a scattered population of cells, the enteroendocrine cells (EECs). EECs sense their environment to secrete hormones in a regulated manner. Distal EECs are in contact with various microbial compounds including hydrogen sulfide (H₂S) which modulate cell respiration with potential consequences on EEC physiology. However, the effect of H₂S on gut hormone secretion remains discussed and the importance of the modulation of cell metabolism on EEC functions remains to be deciphered. The aim of this project was to characterize the metabolic response of EECs to H₂S and the consequences on GLP-1 secretion. We used cell line models of EECs to assess their capacity to metabolize H₂S at low concentration and the associated modulation of cell respiration. We confirmed that like what is observed in colonocytes, colonic EEC model, NCI-h716 cell line rapidly metabolizes H₂S at low concentrations, resulting in transient increased respiration. Higher concentrations of H₂S inhibited this respiration, with the concentration threshold for inhibition depending on cell density. However, increased or inhibited oxidative respiration had little effect on acute GLP-1 secretion. Overall, we present here a first study showing the EEC capacity to detoxify low concentrations of H₂S and used this model to acutely address the importance of cell respiration on secretory activity.

Targeting the microbiota-mitochondria crosstalk in neurodegeneration with senotherapeutics

Neurodegenerative diseases are a group of age-related disorders characterized by a chronic and progressive loss of function and/or structure of synapses, neurons, and glial cells. The etiopathogenesis of neurodegenerative diseases is characterized by a complex network of intricately intertwined pathophysiological processes that are still not fully understood. Safe and effective disease-modifying treatments are urgently needed, but still not available. Accumulating evidence suggests that gastrointestinal dyshomeostasis and microbial dysbiosis might play an important role in neurodegeneration by acting as either primary or secondary pathophysiological factors. The research on the role of microbiota in neurodegeneration is in its early phase; however, accumulating evidence suggests that dysbiosis might promote neurodegenerative diseases by disrupting mitochondrial function and inducing mitochondrial dysfunction-associated senescence (MiDAS), possibly due to bidirectional crosstalk based on the common evolutionary origin of mitochondria and bacteria. Cellular senescence is an onco-supressive homeostatic mechanism that results in an irreversible cell cycle arrest upon exposure to noxious stimuli. Senescent cells resist apoptosis via senescent cell anti-apoptotic pathways (SCAPs) and transition into a state known as senescence-associated secretory phenotype (SASP) that generates a cytotoxic proinflammatory microenvironment. Cellular senescence results in the adoption of a detrimental vicious cycle driven by dysbiosis, mitochondrial dysfunction, inflammation, and oxidative stress - a pathophysiological positive feedback loop that results in neuroinflammation and neurodegeneration. Detrimental effects of MiDAS might be prevented and abolished by mitochondria-targeted senotherapeutics, a group of drugs specifically designed to alleviate senescence by inhibiting SCAPs (senolytics), or inhibiting SASP (senomorphics).

Interaction of Terminal Oxidases with Amphipathic Molecules

The review focuses on recent advances regarding the effects of natural and artificial amphipathic compounds on terminal oxidases. Terminal oxidases are fascinating biomolecular devices which couple the oxidation of respiratory substrates with generation of a proton motive force used by the cell for ATP production and other needs. The role of endogenous lipids in the enzyme structure and function is highlighted. The main regularities of the interaction between the most popular detergents and terminal oxidases of various types are described. A hypothesis about the physiological regulation of mitochondrial-type enzymes by lipid-soluble ligands is considered.

The role of cyanoalanine synthase and alternative oxidase in promoting salt stress tolerance in Arabidopsis thaliana

BACKGROUND

Cyanide is a toxic chemical that inhibits cellular respiration. In plants, cyanide can be produced by themselves, especially under stressful conditions. Cyanoalanine synthase (CAS) is a key enzyme involved in plant cyanide detoxification. There are three genes encoding CAS in Arabidopsis thaliana, but the roles of these genes in the plant's response to stress are less studied. In addition, it is known that alternative oxidase (AOX) mediates cyanide-resistant respiration, but the relationship between CAS and AOX in regulating the plant stress response remains largely unknown.

RESULTS

Here, the effects of the overexpression or mutation of these three CAS genes on salt stress tolerance were investigated. The results showed that under normal conditions, the overexpression or mutation of the CAS genes had no significant effect on the seed germination and growth of Arabidopsis thaliana compared with wild type (WT). However, under 50, 100, and 200 mM NaCl conditions, the seeds overexpressing CAS genes showed stronger salt stress resistance, i.e., higher germination speed than WT seeds, especially those that overexpressed the CYS-C1 and CYS-D1 genes. In contrast, the seeds with CAS gene mutations exhibited salt sensitivity, and their germination ability and growth were significantly damaged by 100 and 200 mM NaCl. Importantly, this difference in salt stress resistance became more pronounced in CAS-OE, WT, and mutant seeds with increasing salt concentration. The CAS-OE seeds maintained higher respiration rates than the WT and CAS mutant seeds under salt stress conditions. The cyanide contents in CAS mutant seeds were approximately 3 times higher than those in WT seeds and more than 5 times higher than those in CAS-OE seeds. In comparison, plants overexpressing CYS-C1 had the fastest detoxification of cyanide and the best salt tolerance, followed by those overexpressing CYS-D1 and CYS-D2. Furthermore, less hydrogen sulfide (H₂S) was observed in CAS-OE seedlings than in WT seedlings under long-term salt stress conditions. Nonetheless, the lack of AOX impaired CAS-OE-mediated plant salt stress resistance, suggesting that CAS and AOX interact to improve salt tolerance is essential. The results also showed that CAS and AOX contributed to the reduction in oxidative damage by helping maintain relatively high levels of antioxidant enzyme activity.

CONCLUSION

In summary, the findings of the present study suggest that overexpression of Arabidopsis CAS family genes plays a positive role in salt stress tolerance and highlights the contribution of AOX to CAS-mediated plant salt resistance, mainly by reducing cyanide and H₂S toxicity.

H2S-Enriched Flush out Does Not Increase Donor Organ Quality in a Porcine Kidney Perfusion Model

Kidney extraction time has a detrimental effect on post-transplantation outcome. This study aims to improve the flush-out and potentially decrease ischemic injury by the addition of hydrogen sulphide (H2S) to the flush medium. Porcine kidneys (n = 22) were extracted during organ recovery surgery. Pigs underwent brain death induction or a Sham operation, resulting in four groups: donation after brain death (DBD) control, DBD H2S, non-DBD control, and non-DBD H2S. Directly after the abdominal flush, kidneys were extracted and flushed with or without H2S and stored for 13 h via static cold storage (SCS) +/− H2S before reperfusion on normothermic machine perfusion. Pro-inflammatory cytokines IL-1b and IL-8 were significantly lower in H2S treated DBD kidneys during NMP (p = 0.03). The non-DBD kidneys show superiority in renal function (creatinine clearance and FENa) compared to the DBD control group (p = 0.03 and p = 0.004). No differences were seen in perfusion parameters, injury markers and histological appearance. We found an overall trend of better renal function in the non-DBD kidneys compared to the DBD kidneys. The addition of H2S during the flush out and SCS resulted in a reduction in pro-inflammatory cytokines without affecting renal function or injury markers.

Assessing the Benefits and Costs of the Hydrogen Cyanide Antiherbivore Defense in Trifolium repens

Understanding the evolution of plant defenses against herbivores requires identifying the benefits and costs of defense. Here, we tested the hypothesis that the benefits and costs of hydrogen cyanide (HCN) defense against herbivory on white clover (Trifolium repens) are temperature dependent. We first tested how temperature affected HCN production in vitro, and then examined how temperature influenced the efficacy of HCN defense of T. repens against a generalist slug (Deroceras reticulatum) herbivore using no-choice and choice feeding trial assays. To understand how temperature affected the costs of defense, plants were exposed to freezing, and HCN production, photosynthetic activity, and ATP concentration were quantified. HCN production increased linearly from 5 °C to 50 °C, and cyanogenic plants experienced reduced herbivory compared to acyanogenic plants only at warmer temperatures when fed upon by young slugs. Freezing temperatures induced cyanogenesis in T. repens and decreased chlorophyll fluorescence. Cyanogenic plants experienced lower ATP levels than acyanogenic plants due to freezing. Our study provides evidence that the benefits of HCN defense against herbivores are temperature dependent, and freezing may inhibit ATP production in cyanogenic plants, but the physiological performance of all plants recovered quickly following short-term freezing. These results contribute to understanding how varying environments alter the benefits and costs of defense in a model system for the study of plant chemical defenses against herbivores.

Local delivery of gaseous signaling molecules for orthopedic disease therapy

Over the past decade, a proliferation of research has used nanoparticles to deliver gaseous signaling molecules for medical purposes. The discovery and revelation of the role of gaseous signaling molecules have been accompanied by nanoparticle therapies for their local delivery. While most of them have been applied in oncology, recent advances have demonstrated their considerable potential in diagnosing and treating orthopedic diseases. Three of the currently recognized gaseous signaling molecules, nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S), are highlighted in this review along with their distinctive biological functions and roles in orthopedic diseases. Moreover, this review summarizes the progress in therapeutic development over the past ten years with a deeper discussion of unresolved issues and potential clinical applications.

Interaction of Amphipathic Peptide from Influenza Virus M1 Protein with Mitochondrial Cytochrome Oxidase

The Bile Acid Binding Site (BABS) of cytochrome oxidase (CcO) binds numerous amphipathic ligands. To determine which of the BABS-lining residues are critical for interaction, we used the peptide P4 and its derivatives A1-A4. P4 is composed of two flexibly bound modified α-helices from the M1 protein of the influenza virus, each containing a cholesterol-recognizing CRAC motif. The effect of the peptides on the activity of CcO was studied in solution and in membranes. The secondary structure of the peptides was examined by molecular dynamics, circular dichroism spectroscopy, and testing the ability to form membrane pores. P4 was found to suppress the oxidase but not the peroxidase activity of solubilized CcO. The K_i(app) is linearly dependent on the dodecyl-maltoside (DM) concentration, indicating that DM and P4 compete in a 1:1 ratio. The true K_i is 3 μM. The deoxycholate-induced increase in K_i(app) points to a competition between P4 and deoxycholate. A1 and A4 inhibit solubilized CcO with K_i(app)~20 μM at 1 mM DM. A2 and A3 hardly inhibit CcO either in solution or in membranes. The mitochondrial membrane-bound CcO retains sensitivity to P4 and A4 but acquires resistance to A1. We associate the inhibitory effect of P4 with its binding to BABS and dysfunction of the proton channel K. Trp residue is critical for inhibition. The resistance of the membrane-bound enzyme to inhibition may be due to the disordered secondary structure of the inhibitory peptide.

The Crosstalk between Microbiome and Mitochondrial Homeostasis in Neurodegeneration

Mitochondria are highly dynamic organelles that serve as the primary cellular energy-generating system. Apart from ATP production, they are essential for many biological processes, including calcium homeostasis, lipid biogenesis, ROS regulation and programmed cell death, which collectively render them invaluable for neuronal integrity and function. Emerging evidence indicates that mitochondrial dysfunction and altered mitochondrial dynamics are crucial hallmarks of a wide variety of neurodevelopmental and neurodegenerative conditions. At the same time, the gut microbiome has been implicated in the pathogenesis of several neurodegenerative disorders due to the bidirectional communication between the gut and the central nervous system, known as the gut-brain axis. Here we summarize new insights into the complex interplay between mitochondria, gut microbiota and neurodegeneration, and we refer to animal models that could elucidate the underlying mechanisms, as well as novel interventions to tackle age-related neurodegenerative conditions, based on this intricate network.

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.

Living on the edge – An overview of invertebrates from groundwater habitats prone to extreme environmental conditions

Groundwater ecosystems from cold polar and circumpolar regions, hot springs, as well as those developed in salt, gypsum or in volcanic rocks are one of the environments considered to exhibit extreme environmental conditions such as low (below 0°C) or high (over 45°C) temperatures, hypersaline waters, or with elevated content of toxic gases like hydrogen sulfide or methane. They represent the “unseen ecosystem beneath our feet” and are inhabited by a large diversity of organisms, persisting and flourishing under severe environmental conditions that are usually hostile to the majority of organisms. These types of groundwater ecosystems are remarkable “evolutionary hotspots” that witnessed the adaptive radiation of morphologically and ecologically diverse species, whereas the organisms living here are good models to understand the evolutionary processes and historical factors involved in speciation and adaptation to severe environmental conditions. Here, we provide an overview of the groundwater invertebrates living in continental groundwater habitats prone to extreme environmental conditions in one or more physico-chemical parameters. Invertebrates are represented by a wide variety of taxonomic groups, however dominated by crustaceans that show specific adaptations mostly metabolic, physiologic, and behavioral. Symbiotic associations among bacteria and invertebrates are also discussed enlightening this biological interaction as a potential adaptation of different groundwater invertebrates to cope with severe environmental conditions. Given the high pressures that anthropogenic activities pose on groundwater habitats worldwide, we predict that several of these highly specialized organisms will be prone to extinction in the near future. Finally, we highlight the knowledge gaps and future research approaches in these particular groundwater ecosystems by using integrative-omic studies besides the molecular approach to shed light on genetic variation and phenotypic plasticity at species and populational levels.

GRAPHICAL ABSTRACT

Energy metabolism disturbance in migraine: From a mitochondrial point of view

Migraine is a serious central nervous system disease with a high incidence rate. Its pathogenesis is very complex, which brings great difficulties for clinical treatment. Recently, many studies have revealed that mitochondrial dysfunction may play a key role in migraine, which affects the hyperosmotic of Ca²⁺, the excessive production of free radicals, the decrease of mitochondrial membrane potential, the imbalance of mPTP opening and closing, and the decrease of oxidative phosphorylation level, which leads to neuronal energy exhaustion and apoptosis, and finally lessens the pain threshold and migraine attack. This article mainly introduces cortical spreading depression, a pathogenesis of migraine, and then damages the related function of mitochondria, which leads to migraine. Oxidative phosphorylation and the tricarboxylic acid cycle are the main ways to provide energy for the body. 95 percent of the energy needed for cell survival is provided by the mitochondrial respiratory chain. At the same time, hypoxia can lead to cell death and migraine. The pathological opening of the mitochondrial permeability transition pore can promote the interaction between pro-apoptotic protein and mitochondrial, destroy the structure of mPTP, and further lead to cell death. The increase of mPTP permeability can promote the accumulation of reactive oxygen species, which leads to a series of changes in the expression of proteins related to energy metabolism. Both Nitric oxide and Calcitonin gene-related peptide are closely related to the attack of migraine. Recent studies have shown that changes in their contents can also affect the energy metabolism of the body, so this paper reviews the above mechanisms and discusses the mechanism of brain energy metabolism of migraine, to provide new strategies for the prevention and treatment of migraine and promote the development of individualized and accurate treatment of migraine.

Host-microbiome metabolism of a plant toxin in bees

While foraging for nectar and pollen, bees are exposed to a myriad of xenobiotics, including plant metabolites, which may exert a wide range of effects on their health. Although the bee genome encodes enzymes that help in the metabolism of xenobiotics, it has lower detoxification gene diversity than the genomes of other insects. Therefore, bees may rely on other components that shape their physiology, such as the microbiota, to degrade potentially toxic molecules. In this study, we show that amygdalin, a cyanogenic glycoside found in honey bee-pollinated almond trees, can be metabolized by both bees and members of the gut microbiota. In microbiota-deprived bees, amygdalin is degraded into prunasin, leading to prunasin accumulation in the midgut and hindgut. In microbiota-colonized bees, on the other hand, amygdalin is degraded even further, and prunasin does not accumulate in the gut, suggesting that the microbiota contribute to the full degradation of amygdalin into hydrogen cyanide. In vitro experiments demonstrated that amygdalin degradation by bee gut bacteria is strain-specific and not characteristic of a particular genus or species. We found strains of Bifidobacterium, Bombilactobacillus, and Gilliamella that can degrade amygdalin. The degradation mechanism appears to vary since only some strains produce prunasin as an intermediate. Finally, we investigated the basis of degradation in Bifidobacterium wkB204, a strain that fully degrades amygdalin. We found overexpression and secretion of several carbohydrate-degrading enzymes, including one in glycoside hydrolase family 3 (GH3). We expressed this GH3 in Escherichia coli and detected prunasin as a byproduct when cell lysates were cultured with amygdalin, supporting its contribution to amygdalin degradation. These findings demonstrate that both host and microbiota can act together to metabolize dietary plant metabolites.