Ratiometric Fluorescence Aptasensor of Allergen Protein Based on Multivalent Aptamer-Encoded DNA Flowers as Fluorescence Resonance Energy Transfer Platform.

Life-threatening allergic reactions to food allergens, particularly peanut protein Ara h1, are a growing public health concern affecting millions of people worldwide. Thus, accurate and rapid detection is necessary for allergen labeling and dietary guidance and ultimately preventing allergic incidents. Herein, we present a novel ratiometric fluorescence aptasensor based on multivalent aptamer-encoded DNA flowers (Mul-DNFs) for the high-stability and sensitive detection of allergen Ara h1. The flower-shaped Mul-DNFs were spontaneously packaged using ultralong polymeric DNA amplicons driven by a rolling circle amplification reaction, which contains a large number of Ara h1 specific recognition units and has excellent binding properties. Furthermore, dual-color fluorescence-labeled Mul-DNFs probes were developed by hybridizing them with Cy3- and Cy5-labeled complementary DNA (cDNA) to serve as a ratiometric fluorescence aptasensor platform based on fluorescence resonance energy transfer. Benefiting from the combined merits of the extraordinary synergistic multivalent binding ability of Mul-DNFs, the excellent specificity of the aptamer, and the sensitivity of the ratiometric sensor to avoid exogenous interference. The developed ratiometric aptasensor showed excellent linearity (0.05-2000 ng mL-1) with a limit of detection of 0.02 ng mL-1. Additionally, the developed ratiometric fluorescence aptasensor was utilized for quantifying the presence of Ara h1 in milk, infant milk powder, cookies, bread, and chocolate with recoveries of 95.7-106.3%. The proposed ratiometric aptasensor is expected to be a prospective universal aptasensor platform for the rapid, sensitive, and accurate determination of food and environmental hazards.

Piceatannol: a renaissance in antibacterial innovation unveiling synergistic potency and virulence disruption against serious pathogens.

In the relentless battle against multi-drug resistant Gram-negative bacteria, piceatannol emerges as a beacon of hope, showcasing unparalleled antibacterial efficacy and a unique ability to disrupt virulence factors. Our study illuminates the multifaceted prowess of piceatannol against prominent pathogens-Proteus mirabilis, Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae. Notably, piceatannol demonstrated a remarkable ability to inhibit biofilm formation, reduce bacterial mobility, and diminish extracellular enzyme synthesis.Mechanistic insights into piceatannol's activity unraveled its impact on membrane potential, proton motive force, and ATP production. Furthermore, our study delved into piceatannol's anti-quorum sensing (QS) activity, showcasing its potential to downregulate QS-encoding genes and affirming its affinity to critical QS receptors through molecular docking. Crucially, piceatannol exhibited a low propensity for resistance development, positioning it as a promising candidate for combating antibiotic-resistant strains. Its mild effect on red blood cells (RBCs) suggests safety even at higher concentrations, reinforcing its potential translational value. In an in vivo setting, piceatannol demonstrated protective capabilities, significantly reducing pathogenesis in mice infected with P. aeruginosa and P. mirabilis. This comprehensive analysis positions piceatannol as a renaissance in antibacterial innovation, offering a versatile and effective strategy to confront the evolving challenges posed by resilient Gram-negative pathogens.

Efficacy and tolerability of monoamine oxidase inhibitors for the treatment of depressive episodes in mood disorders: A systematic review and network meta-analysis.

BACKGROUND: Monoamine oxidase inhibitors (MAOIs) are considered third-line treatments for treatment resistant depression; however, they are underused in clinical practice. AIMS: This study aimed to assess the efficacy, tolerability, and acceptability of MAOIs for the treatment of depression in comparison with other antidepressant treatments. METHODS: A systematic review and network meta-analysis of randomised clinical trials was performed to compare the efficacy, tolerability and acceptability between MAOIs and other antidepressant treatments for the treatment of depressive episodes. RESULTS: A total of 83 double-blinded, randomised controlled trials were included in the analysis, with 7765 participants assigned to an active treatment and 1844 assigned to placebo. Several MAOIs, including isocarboxazid, phenelzine, tranylcypromine and moclobemide, showed significantly higher efficacy compared with placebo. The tolerability and acceptability of MAOIs was comparable to other antidepressants. LIMITATIONS: A disproportionate number of studies investigating the most commonly used MAOIs, such as moclobemide and phenelzine, and a lack of specific studies focusing on treatment-resistant and atypical depression. CONCLUSIONS: MAOIs are similar in efficacy to other antidepressants for the treatment of depression. However, more studies are needed comparing MAOI treatment in people with treatment-resistant, atypical and bipolar depression.

Synthesis, insecticidal Activity, and molecular docking analysis of some benzo[h]quinoline derivatives against Culex pipiens L. Larvae.

Some heterocycles bearing a benzo[h]quinoline moiety were synthesized through treating a 3-((2-chlorobenzo[h]quinolin-3-yl)methylene)-5-(p-tolyl)furan-2(3H)-one with four nitrogen nucleophiles comprising ammonium acetate, benzylamine, dodecan-1-amine, and 1,2-diaminoethane. Also, thiation reactions of furanone and pyrrolinone derivatives were investigated. The insecticidal activity of these compounds against mosquito larvae (Culex pipiens L.) was evaluated. All tested compounds exhibited significant larvicidal activity, surpassing that of the conventional insecticide chlorpyrifos. In silico docking analysis revealed that these compounds may act as acetyl cholinesterase (AChE) inhibitors, potentially explaining their larvicidal effect. Additionally, interactions with other neuroreceptors, such as nicotinic acetylcholine receptor and sodium channel voltage-gated alpha subunit were also predicted. The results obtained from this study reflected the potential of benzo[h]quinoline derivatives as promising candidates for developing more effective and sustainable mosquito control strategies. The ADME (absorption, distribution, metabolism, and excretion) analyses displayed their desirable drug-likeness and oral bioavailability properties.

Rational design and eco-friendly one-pot multicomponent synthesis of novel ethylidenehydrazineylthiazol-4(5H)-ones as potential apoptotic inducers targeting wild and mutant EGFR-TK in triple negative breast cancer.

A novel series of ethylidenehydrazineylthiazol-4(5H)-ones were synthesized using various eco-friendly one-pot multicomponent synthetic techniques. The anticancer activity of compounds (4a-m) was tested against 11 cancer cell lines. While the IC50 of all compounds was evaluated against the most sensitive cell lines (MDA-MB-468 and FaDu). Our SAR study pinpointed that compound 4a, having a phenyl substituent, exhibited a significant growth inhibition % against all cancer cell lines. The frontier anticancer candidates against the MDA-MB-468 were also examined against the wild EGFR (EGFR-WT) and mutant EGFR (EGFR-T790M) receptors. Most of the synthesized compounds exhibited a higher inhibitory potential against EGFR-T790M than the wild type of EGFR. Remarkably, compound 4k exhibited the highest inhibitory activity against both EGFR-WT and EGFR-T790M with IC50 values (0.051 and 0.021 µM), respectively. The pro-apoptotic protein markers (p53, BAX, caspase 3, caspase 6, caspase 8, and caspase 9) and the anti-apoptotic key marker (BCL-2) were also measured to propose a mechanism of action for the compound 4k as an apoptotic inducer for MDA-MB-468. Investigation of the cell cycle arrest potential of compound 4k was also conducted on MDA-MB-468 cancer cells. We also evaluated the inhibitory activities of compounds (4a-m) against both EGFR-WT and EGFR-T790M using two different molecular docking processes.

Mass Spectrometry Applications to Study Human Microbiome.

Microbiotas are an adaptable component of ecosystems, including human ecology. Microorganisms influence the chemistry of their specialized niche, such as the human gut, as well as the chemistry of distant surroundings, such as other areas of the body. Metabolomics based on mass spectrometry (MS) is one of the primary methods for detecting and identifying small compounds generated by the human microbiota, as well as understanding the functional significance of these microbial metabolites. This book chapter gives basic knowledge on the kinds of untargeted mass spectrometry as well as the data types that may be generated in the context of microbiome study. While data analysis remains a barrier, the emphasis is on data analysis methodologies and integrative analysis, particularly the integration of microbiome sequencing data. Mass spectrometry (MS)-based techniques have resurrected culture methods for studying the human gut microbiota, filling in the gaps left by high-throughput sequencing methods in terms of culturing minor populations.

Applications of Proteomics in Probiotics Having Anticancer and Chemopreventive Properties.

Proteomics has grown in importance in molecular sciences because it gives vital information on protein identification, expression levels, and alteration. Cancer is one of the world's major causes of death and is the major focus of much research. Cancer risk is determined by hereditary variables as well as the body's immunological condition. Probiotics have increasing medical importance due to their therapeutic influence on the human body in the prevention and treatment of numerous chronic illnesses, including cancer, with no adverse effects. Several anticancer, anti-inflammatory, and chemopreventive probiotics are studied using different proteomic approaches like two-dimensional gel electrophoresis, liquid chromatography-mass spectrometry, and matrix-assisted laser desorption/ionization mass spectrometry. To gain relevant information about probiotic characteristics, data from the proteomic analysis are evaluated and processed using bioinformatics pipelines. Proteomic studies showed the significance of different proteomic approaches in characterization, comparing strains, and determination of oxidative stress of different probiotics. Moreover, proteomic approaches identified different proteins that are involved in glucose metabolism and the formation of cell walls or cell membranes, and the differences in the expression of critical enzymes in the HIF-1 signaling pathway, starch, and sucrose metabolism, and other critical metabolic pathways.

Synthesis and evaluation of larvicidal efficacy against C. pipiens of some new heterocyclic compounds emanated from 2-cyano-N'-(2-(2,4-dichlorophenoxy)acetyl)acetohydrazide.

Several infectious diseases are transmitted and spread by mosquitoes, and millions of people die annually from them. The mosquito, Culex pipiens is a responsible for the emergence of various Virus in Egypt. So, we devote our work to evaluate the larvicidal efficacy against C. pipiens of some new heterocyclic compounds containing chlorine motifs. The implementation was emanated from using 2-cyano-N'-(2-(2,4-dichlorophenoxy)acetyl)acetohydrazide (3) as scaffold to synthesize some new heterocyclic compounds. The structures of the synthesized compounds were interpreted scrupulously by spectroscopic and elemental analyses. Thereafter, the larvicidal activity against C. pipiens of thirteen synthesized compounds was estimated. Noteworthy, cyanoacetohydrazide derivative 3 and 3-iminobenzochromene derivative 12 showed a fabulous potent efficacy with LC50 equal to 3.2 and 3.5 ppm against C. pipiens, respectively, and are worth being further evaluated in the field of pest control.

Exploring the Antiproliferative Potency of Pyrido[2,3-d]Pyrimidine Derivatives: Studies on Design, Synthesis, Anticancer Evaluation, SAR, Docking, and DFT Calculations.

Herein, an efficient method for the synthesis of a new series of pyrido[2,3-d]pyrimidine derivatives has been adopted through the reaction of hydrazinyl pyrido[2,3-d] pyrimidine derivative (1) with different electrophilic species, such as ethyl cyanoacetate and different 1,3 diketone derivatives, gave the corresponding derivatives (2-5). Meanwhile, pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidines (6-11) were synthesized via reaction of hydrazine derivative 1 with phenylisothiocyanate, potassium thiocyanate, and carbon disulfide. Compound 1 was also submitted to react with different carbonyl compounds to afford pyrido-pyrimidine derivatives (12-15). All the newly synthesized compounds were tested in vitro for their antiproliferative activities against HCT-116 and MCF-7 cell lines. Compounds 2, 3, 7, and 8 displayed very strong inhibitory activity against the two cell lines compared with the standard drug doxorubicin. Furthermore, a docking study of the most active compounds was performed with the thymidylate synthase enzyme (PDB: Code 6qxg). Moreover, DFT calculation was carried out for the most biologically active compounds and a reference drug (Doxorubicin) using the B3LYP/6-31G+(d,p) level of theory. The calculated EHOMO and ELUMO energies were used to calculate the global reactivity parameters. Finally, Molecular electrostatic potential (MEP) and structure activity relationship (SAR) were studied to correlate the relation between chemical structure and reactivity.

Pharmacophore-based, rationale design, and efficient synthesis of novel tetrahydrobenzo[b]thiophene candidates as potential dual Topo I/II inhibitors and DNA intercalators.

A series of tetrahydrobenzo[b]thiophene derivatives was designed and synthesized as dual topoisomerase (Topo) I/II inhibitors implicating potential DNA intercalation. Ethyl-2-amino-3-cyano-4,5,6,7-tetrahydrobenzo[b]thiophene-4-carboxylate (1) was prepared by modification of the Gewald reaction procedure using a Fe2O3 nanocatalyst and then it was used as a building block for the synthesis of tetrahydrobenzo[b]thiophene candidates (2-14). Interestingly, compound 14 showed the best cytotoxic potential against hepatocellular, colorectal, and breast cancer cell lines (IC50 = 7.79, 8.10, and 3.53 µM), respectively, surpassing doxorubicin at breast cancer (IC50 = 4.17 µM). Meanwhile, the Topo I and II inhibition assay displayed that compound 3 could exhibit the best inhibitory potential among the investigated candidates (IC50 = 25.26 and 10.01 nM), respectively, in comparison to camptothecin (IC50 = 28.34 nM) and doxorubicin (IC50 = 11.01 nM), as reference standards. In addition, the DNA intercalation assay showed that compound 14 could display the best binding affinity with an IC50 value of 77.82 µM in comparison to doxorubicin (IC50 = 58.03 µM). Furthermore, cell cycle and apoptosis analyses described that compound 3 prompts the G1 phase arrest in michigan cancer foundation-7 cancer cells and increases the apoptosis ratio by 29.31% with respect to untreated cells (2.25%). Additionally, the conducted molecular docking assured the promising binding of the investigated members toward Topo I and II with potential DNA intercalation. Accordingly, the synthesized compounds could be treated as promising anticancer candidates for future optimization.

Novel Insights into Changes in Gene Expression within the Hypothalamus in Two Asthma Mouse Models: A Transcriptomic Lung-Brain Axis Study.

Patients with asthma experience elevated rates of mental illness. However, the molecular links underlying such lung-brain crosstalk remain ambiguous. Hypothalamic dysfunction is observed in many psychiatric disorders, particularly those with an inflammatory component due to many hypothalamic regions being unprotected by the blood-brain barrier. To gain a better insight into such neuropsychiatric sequelae, this study investigated gene expression differences in the hypothalamus following lung inflammation (asthma) induction in mice, using RNA transcriptome profiling. BALB/c mice were challenged with either bacterial lipopolysaccharide (LPS, E. coli) or ovalbumin (OVA) allergens or saline control (n = 7 per group), and lung inflammation was confirmed via histological examination of postmortem lung tissue. The majority of the hypothalamus was micro-dissected, and total RNA was extracted for sequencing. Differential expression analysis identified 31 statistically significant single genes (false discovery rate FDR5%) altered in expression following LPS exposure compared to controls; however, none were significantly changed following OVA treatment, suggesting a milder hypothalamic response. When gene sets were examined, 48 were upregulated and 8 were downregulated in both asthma groups relative to controls. REACTOME enrichment analysis suggests these gene sets are involved in signal transduction metabolism, immune response and neuroplasticity. Interestingly, we identified five altered gene sets directly associated with neurotransmitter signaling. Intriguingly, many of these altered gene sets can influence mental health and or/neuroinflammation in humans. These findings help characterize the links between asthma-induced lung inflammation and the brain and may assist in identifying relevant pathways and therapeutic targets for future intervention.

Molecular and immunological studies on Theileria equi and its vector in Egypt.

Equine piroplasmosis is not fully understood regarding pathogenicity, prophylaxis, host immune response expression, and specific vectors. Accurately identifying the parasite vector is crucial for developing an effective control plan for a particular infection. This study focused on morphologically identifying two Hyalomma species (H. anatolicum and H. marginatum) and one Rhipicephalus annulatus (R. annulatus) at the species level. The identification process was followed by phylogenetic analysis using the neighbor-joining method based on the cytochrome oxidase subunit 1 (COXI) gene as a specific vector for Theileria equi (T. equi) in horses. T. equi was diagnosed morphologically and molecularly from infected blood samples and crushed tick species using conventional PCR. Subsequently, phylogenetic analysis based on the amplification of the 18 S rRNA gene was conducted. The obtained sequence data were evaluated and registered in GenBank under accession numbers OR064161, OR067911, OR187727, and OR068139, representing the three tick species and the isolated T. equi, respectively. The study demonstrated that T. equi infection leads to immune system suppression by significantly increasing the levels of oxidative stress markers (CAT, GPx, MDA, and SOD) (P ≤ 0.0001), with this elevation being directly proportional to parasitemia levels in infected blood cells. Furthermore, a correlation was observed between parasitemia levels and the expression of immune response infection genes (IFN-gamma, TGF-ß1, and IL-1ß cytokines) in infected horses compared to non-infected equine. Common macroscopic symptoms indicating T. equi infection in horses include intermittent fever, enlarged lymph nodes (LN), and tick infestation.

Discovery of a non-covalent ligand for Rpn-13, a therapeutic target for hematological cancers.

The ubiquitin-proteasome system serves as the major proteolytic degradation pathway in eukaryotic cells. Many inhibitors that covalently bind to the proteasome's active sites have been developed for hematological cancers, but resistance can arise in patients. To overcome limitations of active-site proteasome inhibitors, we and others have focused on developing ligands that target subunits on the 19S regulatory particle (19S RP). One such 19S RP subunit, Rpn-13, is a ubiquitin receptor required for hematological cancers to rapidly degrade proteins to avoid apoptosis. Reported Rpn-13 inhibitors covalently bind to the Rpn-13's Pru domain and have been effective anti-hematological cancer agents. Here, we describe the discovery of TCL-1, a non-covalent binder to the Pru domain. Optimization of TCL-1's carboxylate group to an ester increases its cytotoxicity in hematological cancer cell lines. Altogether, our data provides a new scaffold for future medicinal chemistry optimization to target Rpn-13 therapeutically.

Back to Old Books Toward Affordable Research: Homemade Phenol-Based Reagent for Triphasic RNA Purification.

Covid-19 crisis did hit many socio-economic aspects in the whole world. In the scientific research, the problem is getting even worse, since most of materials and consumable are allocated to the health sector. Many research laboratories around the world have big delay in receiving their purchases to accomplish their research projects. In the developing countries, the situation is much more difficult, since most of the funding resources are directed to the Covid-19 crisis and there is a notable increase in reagents' prices. Therefore, the aim of the present study is to make a homemade reagents for RNA purification from eukaryotic cells/tissues. The homemade phenol-based RNA extraction reagents were prepared using saturated phenol pH 4.3 (adjusted by 0.5 M citrate buffer) and guanidine thiocyanate. To validate the phenol-based reagent, RNA was purified from different biological samples (cell line, tissues, and fungi) using homemade phenol-based versus a commercial one. Concentration of RNA samples extracted from the same number of cells were compared to assess the homemade preparation of phenol-based reagent. In conclusion, homemade phenol-based reagent is cost effective and comparable to the commercial one. Using homemade phenol-based, RNA extraction was successfully purified from different biological sources.

Targeting Cancer Stem Cells as the Key Driver of Carcinogenesis and Therapeutic Resistance.

The emerging concept of cancer stem cells (CSCs) as the key driver behind carcinogenesis, progression, and diversity has displaced the prior model of a tumor composed of cells with similar subsequently acquired mutations and an equivalent capacity for renewal, invasion, and metastasis. This significant change has shifted the research focus toward targeting CSCs to eradicate cancer. CSCs may be characterized using cell surface markers. They are defined by their capacity to self-renew and differentiate, resist conventional therapies, and generate new tumors following repeated transplantation in xenografted mice. CSCs' functional capabilities are governed by various intracellular and extracellular variables such as pluripotency-related transcription factors, internal signaling pathways, and external stimuli. Numerous natural compounds and synthetic chemicals have been investigated for their ability to disrupt these regulatory components and inhibit stemness and terminal differentiation in CSCs, hence achieving clinical implications. However, no cancer treatment focuses on the biological consequences of these drugs on CSCs, and their functions have been established. This article provides a biomedical discussion of cancer at the time along with an overview of CSCs and their origin, features, characterization, isolation techniques, signaling pathways, and novel targeted therapeutic approaches. Additionally, we highlighted the factors endorsed as controlling or helping to promote stemness in CSCs. Our objective was to encourage future studies on these prospective treatments to develop a framework for their application as single or combined therapeutics to eradicate various forms of cancer.

Marine Natural Compound (Neviotin A) Displays Anticancer Efficacy by Triggering Transcriptomic Alterations and Cell Death in MCF-7 Cells.

We investigated the anticancer mechanism of a chloroform extract of marine sponge (Haliclona fascigera) (sample C) in human breast adenocarcinoma (MCF-7) cells. Viability analysis using MTT and neutral red uptake (NRU) assays showed that sample C exposure decreased the proliferation of cells. Flow cytometric data exhibited reactive oxygen species (ROS), nitric oxide (NO), dysfunction of mitochondrial potential, and apoptosis in sample C-treated MCF-7 cells. A qPCR array of sample C-treated MCF-7 cells showed crosstalk between different pathways of apoptosis, especially BIRC5, BCL2L2, and TNFRSF1A genes. Immunofluorescence analysis affirmed the localization of p53, bax, bcl2, MAPKPK2, PARP-1, and caspase-3 proteins in exposed cells. Bioassay-guided fractionation of sample C revealed Neviotin A as the most active compound triggering maximum cell death in MCF-7, indicating its pharmacological potency for the development of a drug for the treatment of human breast cancer.

Evaluation of biochemical, hematological, and genotoxic parameters in mice exposed to individual and combined ethoprophos and cadmium.

Environmental contamination by complex mixtures of pesticides and metals is a major health problem in agriculture and industry. In real life scenarios, we are exposed to mixtures of chemicals rather than single chemicals, and therefore it is critical to assess their toxicity. The current work was conducted to assess the toxic effects of a low dose (2% median lethal dose) of ethoprophos (Etho, 0.16 mg kg-1 bw), and cadmium (Cd, 0.63 mg kg-1 bw); each alone or in combination on hematological, biochemical, and genotoxic parameters in male mice for one or four weeks. The tested toxicants resulted in a decline in body and organs weights, the most hematological indices, acetylcholine esterase activity, and the total protein content, while they significantly increased liver and kidney function parameters. Furthermore, they increased the mitotic index (MI), number of abnormal sperms, and chromosomes. In conclusion, Etho and Cd induce deleterious effects on all tested parameters in male mice which reflect more obvious impacts when both combined, particularly after 28 days of exposure. However, further research is needed to confirm toxicokinetic or toxicodynamic interactions between these two toxic compounds in the organisms.

Enhanced ADO-OFDM-based adaptive digital dimming VLC system.

Visible light communication (VLC) has shown significant growth in recent years. VLC simultaneously offers illumination and communication. In VLC systems, dimming control is used to handle the lighting and energy consumption constraints. In this paper, a new, to the best of our knowledge, adaptive digital dimming optical-orthogonal frequency division multiplexing (ADDO-OFDM) based on pulse width modulation is proposed to combine enhanced asymmetrically clipped DC biased optical OFDM (EADO-OFDM) and negative EADO-OFDM (ENADO-OFDM). It exploits the performance benefits of EADO-OFDM and ENADO-OFDM. The proposed ADDO-OFDM controls the dimming level in a vast range with an acceptable bit error rate with a favorable data length.

A highly selective bulk optode based on 6-{4-(2,4-dihydroxy-phenyl)diazenyl)phenyl}-2-oxo-4-phenyl-1,2-dihydro-pyridine-3-carbonitrile incorporating chromoionophore V for determination of nano levels of cadmium.

A novel optical sensor has been fabricated for highly accurate, simple and selective determination of nanomolar levels of cadmium ions. The sensor depends on the interaction of 6-{4-(2,4-dihydroxyphenyl)diazenyl)phenyl}-2-oxo-4-phenyl-1,2-dihydropyri-dine-3-carbonitrile (DDPODC) with Cd(II) in plasticized (2-nitrophenyloctyl ether) (o-NPOE) polyvinylchloride (PVC) membrane incorporating chromoionophore V as a lipophilic H+-selective indicator. It would seem that the higher Cd(II) concentration, the lower absorbance of chromoionophore V in the membrane at 668 nm, whereas the absorbance at 586 nm increased. The developed sensor at pH 4.7 has a linear range of 5.0 × 10-12 - 2.5 × 10-5 M with limits of detection and quantification of 1.62 × 10-12 and 4.95 × 10-12 M, respectively. The relative standard deviation (RSD) for eight determination of 1.0 × 10-7 M Cd(II) was 1.67%. Finally, the proposed sensor gives good results for applications in the direct determination of cadmium ions in water, food, and biological samples. Additionally, we compared the obtained results with the data obtained from the flame atomic absorption spectrometry (FAAS).

Carbon Source-Dependent Reprogramming of Anaerobic Metabolism in Staphylococcus aureus.

To be a successful pathogen, Staphylococcus aureus has to adapt its metabolism to the typically oxygen- and glucose-limited environment of the host. Under fermenting conditions and in the presence of glucose, S. aureus uses glycolysis to generate ATP via substrate-level phosphorylation and mainly lactic acid fermentation to maintain the redox balance by reoxidation of NADH equivalents. However, it is less clear how S. aureus proceeds under anoxic conditions and glucose limitation, likely representing the bona fide situation in the host. Using a combination of proteomic, transcriptional, and metabolomic analyses, we show that in the absence of an abundant glycolysis substrate, the available carbon source pyruvate is converted to acetyl coenzyme A (AcCoA) in a pyruvate formate-lyase (PflB)-dependent reaction to produce ATP and acetate. This process critically depends on derepression of the catabolite control protein A (CcpA), leading to upregulation of pflB transcription. Under these conditions, ethanol production is repressed to prevent wasteful consumption of AcCoA. In addition, our global and quantitative characterization of the metabolic switch prioritizing acetate over lactate fermentation when glucose is absent illustrates examples of carbon source-dependent control of colonization and pathogenicity factors.IMPORTANCE Under infection conditions, S. aureus needs to ensure survival when energy production via oxidative phosphorylation is not possible, e.g., either due to the lack of terminal electron acceptors or by the inactivation of components of the respiratory chain. Under these conditions, S. aureus can switch to mixed-acid fermentation to sustain ATP production by substrate level phosphorylation. The drop in the cellular NAD+/NADH ratio is sensed by the repressor Rex, resulting in derepression of fermentation genes. Here, we show that expression of fermentation pathways is further controlled by CcpA in response to the availability of glucose to ensure optimal resource utilization under growth-limiting conditions. We provide evidence for carbon source-dependent control of colonization and virulence factors. These findings add another level to the regulatory network controlling mixed-acid fermentation in S. aureus and provide additional evidence for the lifestyle-modulating effect of carbon sources available to S. aureus.