1H NMR based sulfonation reaction kinetics of wine relevant thiols in comparison with known carbonyls.

Sulfite addition is a common tool for ensuring wines' oxidative stability via the activity of its free and weakly bound molecular fraction. As a nucleophile, bisulfite forms covalent adducts with wine's most relevant electrophiles, such as carbonyls, polyphenols, and thiols. The equilibrium in these reactions is often represented as dissociation rather than formation. Recent studies from our laboratory demonstrate, first, the acetaldehyde sulfonate dissociation, and second, the chemical stability of cysteine and epicatechin sulfonates under wine aging conditions. Thus, the objective of this study was to monitor by 1H NMR the binding specificity of known carbonyl-derived SO2 binders (acetaldehyde and pyruvic acid) in the presence of S-containing compounds (cysteine and glutathione). We report that during simulated wine aging, the sulfur dioxide that is rapidly bound to carbonyl compounds will be released and will bind to cysteine and glutathione, demonstrating the long-term sulfur dioxide binding potential of S-containing compounds. These results are meant to serve as a complement to existing literature reviews focused on molecular markers related to wines' oxidative stability and emphasize once more the importance of S-containing compounds in wine aging chemical mechanisms.

Dearomatization drives complexity generation in freshwater organic matter.

Dissolved organic matter (DOM) is one of the most complex, dynamic and abundant sources of organic carbon, but its chemical reactivity remains uncertain1-3. Greater insights into DOM structural features could facilitate understanding its synthesis, turnover and processing in the global carbon cycle4,5. Here we use complementary multiplicity-edited 13C nuclear magnetic resonance (NMR) spectra to quantify key substructures assembling the carbon skeletons of DOM from four main Amazon rivers and two mid-size Swedish boreal lakes. We find that one type of reaction mechanism, oxidative dearomatization (ODA), widely used in organic synthetic chemistry to create natural product scaffolds6-10, is probably a key driver for generating structural diversity during processing of DOM that are rich in suitable polyphenolic precursor molecules. Our data suggest a high abundance of tetrahedral quaternary carbons bound to one oxygen and three carbon atoms (OCqC3 units). These units are rare in common biomolecules but could be readily produced by ODA of lignin-derived and tannin-derived polyphenols. Tautomerization of (poly)phenols by ODA creates non-planar cyclohexadienones, which are subject to immediate and parallel cycloadditions. This combination leads to a proliferation of structural diversity of DOM compounds from early stages of DOM processing, with an increase in oxygenated aliphatic structures. Overall, we propose that ODA is a key reaction mechanism for complexity acceleration in the processing of DOM molecules, creation of new oxygenated aliphatic molecules and that it could be prevalent in nature.

Increased levels of a mycophenolic acid metabolite in patients with kidney failure negatively affect cardiomyocyte health.

Chronic kidney disease (CKD) significantly increases cardiovascular risk and mortality, and the accumulation of uremic toxins in the circulation upon kidney failure contributes to this increased risk. We thus performed a screening for potential novel mediators of reduced cardiovascular health starting from dialysate obtained after hemodialysis of patients with CKD. The dialysate was gradually fractionated to increased purity using orthogonal chromatography steps, with each fraction screened for a potential negative impact on the metabolic activity of cardiomyocytes using a high-throughput MTT-assay, until ultimately a highly purified fraction with strong effects on cardiomyocyte health was retained. Mass spectrometry and nuclear magnetic resonance identified the metabolite mycophenolic acid-ß-glucuronide (MPA-G) as a responsible substance. MPA-G is the main metabolite from the immunosuppressive agent MPA that is supplied in the form of mycophenolate mofetil (MMF) to patients in preparation for and after transplantation or for treatment of autoimmune and non-transplant kidney diseases. The adverse effect of MPA-G on cardiomyocytes was confirmed in vitro, reducing the overall metabolic activity and cellular respiration while increasing mitochondrial reactive oxygen species production in cardiomyocytes at concentrations detected in MMF-treated patients with failing kidney function. This study draws attention to the potential adverse effects of long-term high MMF dosing, specifically in patients with severely reduced kidney function already displaying a highly increased cardiovascular risk.

Discovery of Glycation Products: Unraveling the Unknown Glycation Space Using a Mass Spectral Library from In Vitro Model Systems.

The nonenzymatic reaction between amino acids (AAs) and reducing sugars, also known as the Maillard reaction, is the primary source of free glycation products (GPs) in vivo and in vitro. The limited number of MS/MS records for GPs in public libraries hinders the annotation and investigation of nonenzymatic glycation. To address this issue, we present a mass spectral library containing the experimental MS/MS spectra of diverse GPs from model systems. Based on the conceptional reaction processes and structural characteristics of products, we classified GPs into common GPs (CGPs) and modified AAs (MAAs). A workflow for annotating GPs was established based on the structural and fragmentation patterns of each GP type. The final spectral library contains 157 CGPs, 499 MAAs, and 2426 GP spectra with synthetic model system information, retention time, precursor m/z, MS/MS, and annotations. As a proof-of-concept, we demonstrated the use of the library for screening GPs in unidentified spectra of human plasma and urine. The AAs with the C6H10O5 modification, fructosylation from Amadori rearrangement, were the most found GPs. With the help of the model system, we confirmed the existence of C6H10O5-modified Valine in human plasma by matching both retention time, MS1, and MS/MS without reference standards. In summary, our GP library can serve as an online resource to quickly screen possible GPs in an untargeted metabolomics workflow, furthermore with the model system as a practical synthesis method to confirm their identity.

Nickel-organo compounds as potential enzyme precursors under simulated early Earth conditions.

The transition from inorganic catalysis through minerals to organic catalysis by enzymes is a necessary step in the emergence of life. Our work is elucidating likely reactions at the earliest moments of Life, prior to the existence of enzymatic catalysis, by exploring essential intersections between nickel bioinorganic chemistry and pterin biochemistry. We used a prebiotically-inspired acetylene-containing volcanic hydrothermal experimental environment to shed light on the efficient formation of nickel-organo complexes. The simplest bis(dithiolene)nickel complex (C2H2S2)2Ni was identified by UV/Vis spectroscopy, mass spectrometry, nuclear magnetic resonance. Its temporal progression and possible function in this simulated early Earth atmosphere were investigated by isolating the main bis(dithiolene)nickel species from the primordial experimental setup. Using this approach, we uncovered a significant diversity of nickel-organo compositions by identifying 156 elemental annotations. The formation of acetaldehyde through the subsequent degradation of these organo-metal complexes is intriguing, as it is reminiscent of the ability of Pelobacter acetylenicus to hydrate acetylene to acetaldehyde via its bis(dithiolene)-containing enzyme acetylene hydratase. As our findings mechanistically characterize the role of nickel sulfide in catalyzing the formation of acetaldehyde, this fundamental pre-metabolic reaction could play the role of a primitive enzyme precursor of the enzymatic acetylene metabolism and further strengthen the role of acetylene in the molecular origin of life.

Unraveling the interplay between root exudates, microbiota, and rhizosheath formation in pearl millet.

BACKGROUND: The rhizosheath, a cohesive soil layer firmly adhering to plant roots, plays a vital role in facilitating water and mineral uptake. In pearl millet, rhizosheath formation is genetically controlled and influenced by root exudates. Here, we investigated the impact of root exudates on the microbiota composition, interactions, and assembly processes, and rhizosheath structure in pearl millet using four distinct lines with contrasting soil aggregation abilities. RESULTS: Utilizing 16S rRNA gene and ITS metabarcoding for microbiota profiling, coupled with FTICR-MS metabonomic analysis of metabolite composition in distinct plant compartments and root exudates, we revealed substantial disparities in microbial diversity and interaction networks. The ß-NTI analysis highlighted bacterial rhizosphere turnover driven primarily by deterministic processes, showcasing prevalent homogeneous selection in root tissue (RT) and root-adhering soil (RAS). Conversely, fungal communities were more influenced by stochastic processes. In bulk soil assembly, a combination of deterministic and stochastic mechanisms shapes composition, with deterministic factors exerting a more pronounced role. Metabolic profiles across shoots, RT, and RAS in different pearl millet lines mirrored their soil aggregation levels, emphasizing the impact of inherent plant traits on microbiota composition and unique metabolic profiles in RT and exudates. Notably, exclusive presence of antimicrobial compounds, including DIMBOA and H-DIMBOA, emerged in root exudates and RT of low aggregation lines. CONCLUSIONS: This research underscores the pivotal influence of root exudates in shaping the root-associated microbiota composition across pearl millet lines, entwined with their soil aggregation capacities. These findings underscore the interconnectedness of root exudates and microbiota, which jointly shape rhizosheath structure, deepening insights into soil-plant-microbe interactions and ecological processes shaping rhizosphere microbial communities. Deciphering plant-microbe interactions and their contribution to soil aggregation and microbiota dynamics holds promise for the advancement of sustainable agricultural strategies. Video Abstract.

Chemical Stability of Thiol and Flavanol Sulfonation Products during Wine Aging Conditions.

Bisulfite (HSO3-) is the predominant form of sulfur dioxide, present as free and bound to wine relevant electrophiles under wine acidic pH. While sulfonation reactions of flavanols and thiols have been recently reported as key for wine preservation against oxidation, the transient mechanisms and physicochemical parameters responsible for that remain unknown. In the present study, sulfonation reaction kinetics of thiols and flavanols were monitored under simulated wine aging conditions. The reaction products were then characterized by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis, and their chemical stability during time was determined by 1H NMR spectroscopy. Thiol and flavanol sulfonation reaction yields were both promoted by the presence of iron and oxygen, while their chemical stability was confirmed under the same conditions. The sulfonation derivatives of epicatechin and cysteine were synthesized and quantified in young and aged wines. Higher concentrations were reported for both metabolites in older wines, indicating their participation on the strongly bound sulfur dioxide fraction. These findings offer new prospects for more precise use of sulfur dioxide in winemaking.

Evaluating the photochemical reactivity of disinfection byproducts formed during seawater desalination processes.

Reverse osmosis (RO) is widely used for seawater desalination but pre-chlorination of intake water produces halogenated disinfection byproducts (DBPs). The fate and environmental impacts associated with the discharge of DBP-containing RO brine wastewater are unknown. Therefore, to evaluate if photochemistry plays a role in DBP degradation in seawater, we collected samples at a desalination plant, which were desalted and concentrated using two-inline solid phase extraction (SPE) techniques combining reverse-phase polymeric (PPL) and weak anion exchange (WAX) resins. Both filtered water samples and SPE samples (extracts reconstituted in open ocean seawater) were exposed to simulated sunlight in a custom-built flow-through system. Optical property analysis during irradiation experiments did not provide distinguishing features between intake water and RO reject water (brine). Extractable organic bromine (organoBr) concentrations were low in intake water samples (7.8 µg Br L-1) and did not change significantly due to irradiation. OrganoBr concentrations in laboratory-chlorinated raw water were much higher (135 µg Br L-1) and on average decreased by 42 % after 24 h irradiation. However, while organoBr concentrations were highest in RO reject water (473 µg Br L-1), changes in organoBr concentrations in PPL SPE samples after 24 h irradiation were variable, ranging from a 1-46 % loss. Furthermore, most bromine-containing molecular ions identified by high resolution mass spectrometry that were present in RO reject water before irradiation were also found after both 24 h and 50 h exposures. Although only one RO reject water sample was tested in this study, results highlight that hundreds of yet to be identified brominated DBPs in RO reject water could be resistant to photodegradation or phototransform into existing DBPs in the environment. Future work examining the biolability of DBPs in RO reject water, as well as the interplay between photochemical and biological DBP cycling, is warranted.

Molecular Characterization of Cooking Processes: A Metabolomics Decoding of Vaporous Emissions for Food Markers and Thermal Reaction Indicators.

Thermal processing of food plays a fundamental role in everyday life. Whereas most researchers study thermal processes directly in the matrix, molecular information in the form of non- and semivolatile compounds conveyed by vaporous emissions is often neglected. We performed a metabolomics study of processing emissions from 96 different food items to define the interaction between the processed matrix and released metabolites. Untargeted profiling of vapor samples revealed matrix-dependent molecular spaces that were characterized by Fourier-transform ion cyclotron resonance-mass spectrometry and ultra-performance liquid chromatography-mass spectrometry. Thermal degradation products of peptides and amino acids can be used for the differentiation of animal-based food from plant-based food, which generally is characterized by secondary plant metabolites or carbohydrates. Further, heat-sensitive processing indicators were characterized and discussed in the background of the Maillard reaction. These reveal that processing emissions contain a dense layer of information suitable for deep insights into food composition and control of cooking processes based on processing emissions.

Soluble organic matter Molecular atlas of Ryugu reveals cold hydrothermalism on C-type asteroid parent body.

The sample from the near-Earth carbonaceous asteroid (162173) Ryugu is analyzed in the context of carbonaceous meteorites soluble organic matter. The analysis of soluble molecules of samples collected by the Hayabusa2 spacecraft shines light on an extremely high molecular diversity on the C-type asteroid. Sequential solvent extracts of increasing polarity of Ryugu samples are analyzed using mass spectrometry with complementary ionization methods and structural information confirmed by nuclear magnetic resonance spectroscopy. Here we show a continuum in the molecular size and polarity, and no organomagnesium molecules are detected, reflecting a low temperature and water-rich environment on the parent body approving earlier mineralogical and chemical data. High abundance of sulfidic and nitrogen rich compounds as well as high abundance of ammonium ions confirm the water processing. Polycyclic aromatic hydrocarbons are also detected in a structural continuum of carbon saturations and oxidations, implying multiple origins of the observed organic complexity, thus involving generic processes such as earlier carbonization and serpentinization with successive low temperature aqueous alteration.

Farnesoid X receptor activation by bile acids suppresses lipid peroxidation and ferroptosis.

Ferroptosis is a regulated cell death modality that occurs upon iron-dependent lipid peroxidation. Recent research has identified many regulators that induce or inhibit ferroptosis; yet, many regulatory processes and networks remain to be elucidated. In this study, we performed a chemical genetics screen using small molecules with known mode of action and identified two agonists of the nuclear receptor Farnesoid X Receptor (FXR) that suppress ferroptosis, but not apoptosis or necroptosis. We demonstrate that in liver cells with high FXR levels, knockout or inhibition of FXR sensitized cells to ferroptotic cell death, whereas activation of FXR by bile acids inhibited ferroptosis. Furthermore, FXR inhibited ferroptosis in ex vivo mouse hepatocytes and human hepatocytes differentiated from induced pluripotent stem cells. Activation of FXR significantly reduced lipid peroxidation by upregulating the ferroptosis gatekeepers GPX4, FSP1, PPARα, SCD1, and ACSL3. Together, we report that FXR coordinates the expression of ferroptosis-inhibitory regulators to reduce lipid peroxidation, thereby acting as a guardian of ferroptosis.

FT-ICR-MS reveals the molecular imprints of the brewing process.

The study of fermentation and brewing has a long history of pioneering discoveries that continue to influence modern industrial food production. Since then, numerous research endeavors have yielded conventional criteria that guide contemporary brewing practices. However, the intricate open challenges faced today necessitate a more exhaustive understanding of the process at the molecular scale. We have developed an ultra-high-resolution mass spectrometric analysis (FT-ICR-MS) of the brewing process that can rapidly and comprehensively resolve thousands of molecules. This approach allows us to track molecular fluctuation during brewing at the level of chemical compositions. Employing biological triplicates, our investigation of two brewing lines that are otherwise identical except for the malt used revealed over 8,000 molecular descriptors of the brewing process. Metabolite imprints of both the similarities and differences arising from deviating malting temperatures were visualized. Additionally, we translated traditional brewing attributes such as the EBC-value, free amino nitrogen, pH-value, and concentration curves of specific molecules, into highly correlative molecular patterns consisting of hundreds of metabolites. These in-depth molecular imprints provide a better understanding of the molecular circumstances leading to various changes throughout the brewing process. Such chemical maps go beyond the observation of traditional brewing attributes and are of great significance in the investigation strategies of current open challenges in brewing research. The molecular base of knowledge, along with advancements in technological and data integration schemes, can facilitate the efficient monitoring of brewing and other productions processes.

Selectivity of ß-Cyclodextrin Polymer toward Aquatic Contaminants: Insights from Ultrahigh-Resolution Mass Spectrometry of Dissolved Organic Matter.

Selectivity in solid-phase extraction (SPE) materials has become increasingly important for analyte enrichment in sensitive analytical workflows to alleviate detrimental matrix effects. Molecular-level investigation of matrix constituents, which are preferentially extracted or excluded, can provide the analytical chemist with valuable information to learn about their control on sorbent selectivity. In this work, we employ nontargeted Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) to elucidate the molecular chemodiversity of freshwater-derived dissolved organic matter (DOM) extracted by the selective model sorbent ß-cyclodextrin polymer (ß-CDP) in comparison to conventional, universal SPE sorbents (i.e., Oasis HLB, Supel-Select HLB, and LiChrolut EN). Statistical analysis of MS data corroborated the highly selective nature of ß-CDP by revealing the extracted DOM spectra that are most dissimilar to original compositions. We found that its selectivity was characterized by pronounced discrimination against highly oxygenated and unsaturated DOM compounds, which were associated with the classes of lignin-like, tannin-like, and carboxylic-rich alicyclic molecules. In contrast, conventional sorbents excluded less highly oxygenated compounds and showed a more universal extraction behavior for a wide range of DOM compositional space. We lay these findings in a larger context that aids the analyst in obtaining an a priori estimate of sorbent selectivity toward any target analyte of interest serving thereby an optimization of sample preparation. This study highlights the great value of nontargeted ultrahigh-resolution MS for better understanding of targeted analytics and provides new insights into the selective sorption behavior of novel sorbents.

C2-addition patterns emerging from acetylene and nickel sulfide in simulated prebiotic hydrothermal conditions.

Chemical complexity is vital not only for the origin of life but also for biological evolution. The chemical evolution of a complex prebiotic mixture containing acetylene, carbon monoxide (CO), and nickel sulfide (NiS) has been analyzed with mass spectrometry as an untargeted approach to reaction monitoring. Here we show through isotopic 13C-labelling, multiple reaction products, encompassing diverse CHO and CHOS compounds within the complex reaction mixture. Molecules within the same chemical spaces displayed varying degrees of 13C-labelling, enabling more robust functional group characterization based on targeted investigations and differences in saturation levels among the described classes. A characteristic C2-addition pattern was detected in all compound classes in conjunction with a high diversity of thio acids, reminiscent of extant microbial C2-metabolism. The analysis involved a time-resolved molecular network, which unveiled the behavior of sulfur in the system. At the onset of the reaction, early formed compounds contain more sulfur atoms compared to later emerging compounds. These results give an essential insight into the still elusive role of sulfur dynamics in the origin of life. Moreover, our results provide temporally resolved evidence of the progressively increasing molecular complexity arising from a limited number of compounds.

Blue-green fluorescence during hypersensitive cell death arises from phenylpropanoid deydrodimers.

Infection of Arabidopsis with avirulent Pseudomonas syringae and exposure to nitrogen dioxide (NO2) both trigger hypersensitive cell death (HCD) that is characterized by the emission of bright blue-green (BG) autofluorescence under UV illumination. The aim of our current work was to identify the BG fluorescent molecules and scrutinize their biosynthesis, localization, and functions during the HCD. Compared with wild-type (WT) plants, the phenylpropanoid-deficient mutant fah1 developed normal HCD except for the absence of BG fluorescence. Ultrahigh resolution metabolomics combined with mass difference network analysis revealed that WT but not fah1 plants rapidly accumulate dehydrodimers of sinapic acid, sinapoylmalate, 5-hydroxyferulic acid, and 5-hydroxyferuloylmalate during the HCD. FAH1-dependent BG fluorescence appeared exclusively within dying cells of the upper epidermis as detected by microscopy. Saponification released dehydrodimers from cell wall polymers of WT but not fah1 plants. Collectively, our data suggest that HCD induction leads to the formation of free BG fluorescent dehydrodimers from monomeric sinapates and 5-hydroxyferulates. The formed dehydrodimers move from upper epidermis cells into the apoplast where they esterify cell wall polymers. Possible functions of phenylpropanoid dehydrodimers are discussed.

Discriminative Behavior of Cyclodextrin Polymers against Dissolved Organic Matter: Role of Cavity Size and Sorbate Properties.

Cyclodextrin polymers (CDPs) are promising next-generation adsorbents in water purification technologies. The selectivity of the polymer derivate cross-linked with tetrafluoroterephthalonitrile (TFN-CDP) for nonionic and cationic micropollutants (MPs) over dissolved organic matter (DOM) renders the adsorbent also attractive for many analytical applications. The molecular drivers of the observed selectivity are, nonetheless, not yet fully understood. To provide new insights into the sorption mechanism, we (i) synthesized TFN-CDPs with different cavity sizes (α-, ß-, γ-CDP); (ii) assessed their extraction efficiencies for selected nonionic MPs in competition with different DOM size fractions (<1, 1-3, 3-10, >10 kDa) to test for size-selectivity; and (iii) performed nontargeted, ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry analysis on CDP-extracted DOM compounds (<1 kDa) to probe for molecular sorbate properties governing their selective sorption. First, no evidence of size-selectivity was obtained through either the different CD cavity sizes (i) or the two independent approaches (ii) and (iii). Second, we found a dominant impact of sorbate oxygenation and polarity on the extraction of DOM and MPs, respectively, with relatively oxygen-poor/nonpolar molecules favorably retained on all α-, ß-, and γ-CDP. Third, our data indicates exclusion of an anionic matrix, such as carboxylic acids, but preferential sorption of cationic nitrogen-bearing DOM, pointing at repulsive and attractive forces with the negatively charged cross-linker as a likely reason. Therefore, we ascribe TFN-CDP's selectivity to nonpolar and electrostatic interactions between MPs/DOM and the polymer building blocks. These molecular insights can further aid in the optimization of efficient and selective sorbent design for environmental and analytical applications.

Chemical evolution of primordial salts and organic sulfur molecules in the asteroid 162173 Ryugu.

Samples from the carbonaceous asteroid (162173) Ryugu provide information on the chemical evolution of organic molecules in the early solar system. Here we show the element partitioning of the major component ions by sequential extractions of salts, carbonates, and phyllosilicate-bearing fractions to reveal primordial brine composition of the primitive asteroid. Sodium is the dominant electrolyte of the salt fraction extract. Anions and NH4+ are more abundant in the salt fraction than in the carbonate and phyllosilicate fractions, with molar concentrations in the order SO42- > Cl- > S2O32- > NO3- > NH4+. The salt fraction extracts contain anionic soluble sulfur-bearing species such as Sn-polythionic acids (n < 6), Cn-alkylsulfonates, alkylthiosulfonates, hydroxyalkylsulfonates, and hydroxyalkylthiosulfonates (n < 7). The sulfur-bearing soluble compounds may have driven the molecular evolution of prebiotic organic material transforming simple organic molecules into hydrophilic, amphiphilic, and refractory S allotropes.

Formation of vesicular structures from fatty acids formed under simulated volcanic hydrothermal conditions.

Microscopic compartmentalization is beneficial in synthetic chemistry and indispensable for the evolution of life to separate a reactive "inside" from a hydrolyzing "outside". Here, we show compartmentalization in aqueous solution containing mixtures of fatty acids up to 19 carbon atoms which were synthesized by one-pot reactions of acetylene and carbon monoxide in contact with nickel sulfide at 105 °C, reaction requirements which are compatible to Hadean Early Earth conditions. Based on confocal, dynamic light scattering (DLS) and transmission electron microscopy (TEM) measurements, vesicle-like structures with diameters of 10-150 nm are formed after solvent extraction and resolubilisation. Moreover fluorescent dye was encapsulated into the structures proving their vesicular properties. This self-assembly could also have occurred on Early Earth as a crucial step in establishing simple membranes of proto-cells as a prerequisite in the evolution of metabolism and life.

Distinct Non-conservative Behavior of Dissolved Organic Matter after Mixing Solimões/Negro and Amazon/Tapajós River Waters.

Positive and negative electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry and 1H NMR revealed major compositional and structural changes of dissolved organic matter (DOM) after mixing two sets of river waters in Amazon confluences: the Solimões and Negro Rivers (S + N) and the Amazon and Tapajós Rivers (A + T). We also studied the effects of water mixing ratios and incubation time on the composition and structure of DOM molecules. NMR spectra demonstrated large-scale structural transformations in the case of S + N mixing, with gain of pure and functionalized aliphatic units and loss of all other structures after 1d incubation. A + T mixing resulted in comparatively minor structural alterations, with a major gain of small aliphatic biomolecular binding motifs. Remarkably, structural alterations from mixing to 1d incubation were in essence reversed from 1d to 5d incubation for both S + N and A + T mixing experiments. Heterotrophic bacterial production (HBP) in endmembers S, N, and S + N mixtures remained near 0.03 µgC L-1 h-1, whereas HBP in A, T, and A + T were about five times higher. High rates of dark carbon fixation took place at S + N mixing in particular. In-depth biogeochemical characterization revealed major distinctions between DOM biogeochemical changes and temporal evolution at these key confluence sites within the Amazon basin.

Interplay of Metallome and Metabolome in Amyotrophic Lateral Sclerosis: A Study on Cerebrospinal Fluid of Patients Carrying Disease-Related Gene Mutations.

Amyotrophic lateral sclerosis (ALS) is a lethal progressive neurodegenerative disease, characterized by a loss of function of upper and lower motor neurons. This study aimed to explore probable pathological alterations occurring in individuals with ALS compared to neurologically healthy controls through the analysis of cerebrospinal fluid (CSF), a medium, which directly interacts with brain parenchyma. A total of 7 ALS patients with disease-associated mutations (ATXN2, C9ORF72, FUS, SOD1, and TARDBP) and 13 controls were included in the study. Multiple analytical approaches were employed, including metabolomic and metallomics profiling, as well as genetic screening, using CSF samples obtained from the brain compartment. Data analysis involved the application of multivariate statistical methods. Advanced hyphenated selenium and redox metal (iron, copper, and manganese) speciation techniques and nontargeted Fourier transform ion cyclotron resonance mass spectrometry-based metabolomics were used for data acquisition. Nontargeted metabolomics showed reduced steroids, including sex hormones; additionally, copper and manganese species were found to be the most relevant features for ALS patients. This indicates a potential alteration of sex hormone pathways in the ALS-affected brain, as reflected in the CSF.