Distribution Of Metabolites Research Articles

Circulating metabolites associate with the QT interval in individuals without prevalent cardiovascular disease

Abstract Background Patients with metabolic syndrome have a higher prevalence of heart-rate corrected QT (QTc) interval prolongation. Despite this the effect of circulating metabolites on the QTc is largely unknown and limited to small studies. Purpose To test for association of circulating metabolites with the QTc interval in the UK Biobank study. Methods Participants were identified from the UK Biobank with same day plasma metabolite profiling and electrocardiograms. All 249 metabolites measured underwent quality control and log transformation to account for rightward skew and zero values. 149 metabolites with inter-correlations >0.7 were excluded. Participants taking QTc-prolonging medication or with a history of ischaemic heart disease or heart failure up to 6 months after the visit, were excluded. Participants were allocated to a training group (N=21,610) or an independent test group (N=5,304), if samples were obtained at recruitment or at a second visit, respectively. In the training group, each metabolite was tested separately for association with the QTc in linear regression analyses, adjusted for clinical covariates (age, sex, fasting time, body mass index (BMI), systolic blood pressure (SBP), smoking status, diabetes, lipid-lowering drug use and dietary factors). Significant metabolites (P<5x10-4) underwent validation in the test group. Sex-stratified analyses were also performed. In the training group, variables in two models underwent regularisation by LASSO regression (10-fold cross-validation) to reduce multicollinearity and downweigh less important variables; 1) clinical variables, 2) clinical variables and validated metabolites. Coefficients were used for QTc prediction in the test group. Significance between the models was evaluated by fisher’s transformation of R-squared statistics. Results In the per metabolite multivariate analysis, 56 metabolites were associated with the QTc interval. 19 metabolites validated in the test group. For 14 of these, absolute effect sizes were >5ms when comparing individuals in the top decile of the metabolite distribution verses the bottom (Figure 1), including the ketone body 3-hydroxybutyrate (9ms), and omega-6 fatty acid to total fatty acid ratio (7.2ms). For associations in males and females separately, significant effect size differences (P<0.05) were observed for 9 metabolites (Figure 2). In the training group, the combined LASSO model selected 17 (of 19) metabolites along with age, sex, SBP and BMI. In the test group, this model R-squared was 0.115 compared with 0.081 for clinical covariates alone, representing a significant 41.9% increase in QTc variation explained (P=0.002). Conclusions This study demonstrates clinically relevant metabolite associations with the QTc in individuals without cardiovascular disease and explain a significant proportion of QTc variation. Further investigation is warranted to test for direct effects on cardiac electrophysiology and proarrhythmic potential.Validated metabolitesSignificant sex differences

Exploring the medicinal potential of Dendrobium: Uncovering the spatial distribution of flavonoids and alkaloids in 15 species of Dendrobium using MALDI-MSI

Dendrobium, the second largest genus in the Orchidaceae family, has been regarded as a valuable medicinal plant throughout Chinese history. Secondary metabolites present in the stem of Dendrobium, including alkaloids and flavonoids, confer significant pharmacological effects such as anti-inflammatory, antibacterial, immunomodulatory, antitumor, and antioxidant properties. To our knowledge, this study is the first to apply matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) technology to comprehensively identify the spatial distribution of secondary metabolites, particularly flavonoids and alkaloids, in the mature stems of 15 common Dendrobium species. By analyzing the matching scores and relative concentrations of compounds, 20 flavonoids and 19 alkaloids with high identification credibility were identified, along with 4 sesquiterpenoid compounds. Their spatial distributions and compositions were analyzed, and the results revealed that despite the similar structural basis of the stems in the 15 Dendrobium species, significant differences existed in the distribution of secondary metabolites among different species. Flavonoids and alkaloids with different medicinal effects exhibited certain specific distribution patterns; for instance, flavonoids with antioxidant effects were mostly concentrated in the outer circle of thin-walled cells of Dendrobium stems, whereas those with antitumor effects were found in higher concentrations in the central areas of some Dendrobium species than in the periphery. Alkaloids with antitumor properties typically exhibited a higher concentration in peripheral thin-walled cells than in central regions. Furthermore, statistical analysis was conducted on the content of secondary metabolites with different effects among the 15 Dendrobium species to identify species with greater medicinal potential in terms of antioxidant and antitumor effects. The findings of this study not only enhance our understanding of the distribution patterns of flavonoids and alkaloids within Dendrobium stems but also offer valuable insights for the medicinal development and quality assessment of Dendrobium.

The improbability of detecting trade-offs and some practical solutions.

Trade-offs are a fundamental concept in evolutionary biology because they are thought to explain much of nature's biological diversity, from variation in life-histories to differences in metabolism. Despite the predicted importance of trade-offs, they are notoriously difficult to detect. Here we contribute to the existing rich theoretical literature on trade-offs by examining how the shape of the distribution of resources or metabolites acquired in an allocation pathway influences the strength of trade-offs between traits. We further explore how variation in resource distribution interacts with two aspects of pathway complexity (i.e., the number of branches and hierarchical structure) affects tradeoffs. We simulate variation in the shape of the distribution of a resource by sampling 106 individuals from a beta distribution with varying parameters to alter the resource shape. In a simple "Y-model" allocation of resources to two traits, any variation in a resource leads to slopes less than -1, with left skewed and symmetrical distributions leading to negative relationships between traits, and highly right skewed distributions associated with positive relationships between traits. Adding more branches further weakens negative and positive relationships between traits, and the hierarchical structure of pathways typically weakens relationships between traits, although in some contexts hierarchical complexity can strengthen positive relationships between traits. Our results further illuminate how variation in the acquisition and allocation of resources, and particularly the shape of a resource distribution and how it interacts with pathway complexity, makes its challenging to detect trade-offs. We offer several practical suggestions on how to detect trade-offs given these challenges.

Effects of Pine Pollen Polysaccharides and Sulfated Polysaccharides on Ulcerative Colitis in Mice by Regulating Th17/Treg.

This study was to investigate the effects of the polysaccharides (PPM60-III) and sulfated polysaccharides (SPPM60-III) of pine pollen on the Th17/Treg balance, inflammatory cytokines, intestinal microbiota, and metabolite distribution in 3% DSS drinking water-induced UC mice. First of all, the physiological results showed that PPM60-III and SPPM60-III could alleviate UC, which was shown by the reduction in liver Treg cells, the rebalance of Th17/Treg, and the modulation of inflammatory cytokines. In addition, the 16S rRNA results showed that PPM60-III and SPPM60-III could decrease Beijerinck and Bifidobacterium, and increase Akkermansia, Escherichia coli, and Fidobacteria. Finally, the metabonomics results showed that PPM60-III and SPPM60-III also restored purine and glycerolipid metabolism, up-regulated nicotinate and nicotinamide metabolism and caffeine metabolism to inhibit inflammation. In conclusion, PPM60-III and SPPM60-III could inhibit UC by regulating gut bacteria composition and metabolite distribution; SPPM60-III showed better anti-colitis activity.

Molecular Imaging of Human Brain Organoids Using Mass Spectrometry.

Brain organoid models serve as a powerful tool for studying human brain development and function. Mass spectrometry imaging (MSI), a cutting-edge technology, allows us to map the spatial distribution of diverse molecules such as lipids, sugars, amino acids, drugs, and their metabolites within these organoids, all without the need for specific molecular probes. High-quality MSI data hinge on meticulous sample preparation. Fixatives play a pivotal role, but conventional options such as glutaraldehyde, paraformaldehyde, and cryopreserving such as sucrose may inadvertently impact tissue metabolites. Optimal fixation entails flash freezing in liquid nitrogen. However, for small organoids, a more suitable approach involves transitioning the organoids directly from the incubator into a warmed embedding solution, followed by freezing in dry ice-cooled ethanol. Another critical step is the embedding prior to cryosectioning, which also requires materials compatible with MSI, as traditional options can interfere with matrix deposition and ionization. Here, an optimized protocol for high resolution-MALDI-MSI of human brain organoids is presented, encompassing sample preparation, sectioning, and imaging using mass spectrometry. This method showcases the molecular distribution of small metabolites, such as amino acids, with high mass accuracy and sensitivity. As such, coupled with complementary studies of brain organoids, it can assist in illuminating complex processes governing early brain development, metabolic cell fate trajectories, and distinctive metabolite signatures. Furthermore, it provides insights into the precise locations of molecules within the organoid, enriching our understanding of the spatial organization of 3D brain organoid models. As the field continues to advance, a growing number of studies leveraging MSI to delve into brain organoids and complex biological systems is anticipated, thereby deepening the understanding of the metabolic aspects of human brain function and development.

Profiling Metabolites Distribution among Various Leaf Layers of Chinese Cabbage

Chinese cabbage is an important vegetable from both a nutritional and an economic standpoint, with the leafy head serving as the primary harvested organ. However, the nutrient accumulation as well as influencing factors within the leafy head have not yet been elucidated. Thus, the distribution of metabolites (soluble sugars, minerals, carotenoids, vitamin C, flavonoid compounds, glucosinolates, and total phenolic compounds) were investigated in different leaf layers of Chinese cabbage with varying head types. The results showed that the inner leaves consistently displayed markedly higher levels of fructose and glucose when contrasted with the outer leaves. Similarly, there was an accumulation of glucosinolates in the inner leaves. By contrast, however, the antioxidants content exhibited a consistent decline from the outer leaves towards the central core, in line with the diminishing antioxidant capacity. This descending trend was also apparent in the mineral content, encompassing calcium, sodium, magnesium and sulfur. These results will provide dietary instruction, especially for consumers who have particular dietary needs.

The assessment of pharmacokinetics and neuroprotective effect of berberine hydrochloride-embedded albumin nanoparticles via various administration routes: comparative in-vivo studies in rats.

The current study aimed to evaluate the pharmacokinetics and neuroprotective effect of well-characterised berberine-bovine serum albumin (BBR-BSA) nanoparticles. BBR-BSA nanoparticles were generated by desolvation method. Entrapment efficiency, loading capacity, particle size, polydispersity index, surface morphology, thermal stability, and in-vitro release were estimated. In-vitro pharmacokinetic and tissue distribution were conducted. Their neuroprotection was evaluated against lipopolysaccharides-induced neurodegeneration. BBR-BSA nanoparticles showed satisfactory particle size (202.60 ± 1.20 nm) and entrapment efficiency (57.00 ± 1.56%). Results confirmed the formation of spheroid-thermal stable nanoparticles with a sustained drug release over 48 h. Sublingual and intranasal routes had higher pharmacokinetic plasma profiles than other routes, with Cmax values at 0.75 h (444 ± 77.79 and 259 ± 42.41 ng/mL, respectively). BBR and its metabolite distribution in the liver and kidney were higher than in plasma. Intranasal and sublingual treatment improves antioxidants, proinflammatory, amyloidogenic biomarkers, and brain architecture, protecting the brain. In conclusion, neuroinflammation and neurodegeneration may be prevented by intranasal and sublingual BBR-BSA nanoparticles.

The influence of spatial distribution and transcriptional regulation of secondary metabolites on the bioactivities of Adenophora triphylla (Japanese lady bell)

The distribution of secondary metabolites in plant tissues plays a crucial role in determining their pharmacological properties. In this study, we investigated the dynamics of the bioactive compounds in Adenophora triphylla, a medicinal herb with diverse therapeutic applications.The anti-inflammatory properties of the EtOAc fraction from the aerial part extract (A_ EtF) exhibited an IC50 value of 27.2 ± 2.3 μg/mL, significantly surpassing that of the EtOAc fraction from the root extract (R_EtF) with an IC50 of 38.9 ± 2.9 μg/mL. Similarly, the anti-melanogenic activity of A_EtF (IC50 = 68.9 ± 2.3 μg/mL) outperformed that of R_EtF (IC50 = 90.0 ± 5.5 μg/mL). Analysis of the distinct chemical profiles of these tissues using UPLC-ESI-Q-TOF-MS revealed that the distribution of secondary metabolites contributes to the observed variations in pharmacological properties between the aerial parts and roots. Transcriptome analysis further elucidated spatially regulated genes associated with secondary metabolism, highlighting the role of AbtYABBYs as potential regulators of phenylpropanoid biosynthesis. To validate their function, these genes were transiently expressed in tobacco leaves via agro-infiltration, confirming their role in modulating polyphenolic compound biosynthesis. Our findings underscore the importance of understanding spatial gene expression patterns for harnessing the complete pharmacological potential of medicinal plants. This study provides valuable insights into the spatial regulation of secondary metabolism and lays the groundwork for targeted manipulation of plant bioactivity for therapeutic and industrial applications.

In situ metabolomic analysis of osteonecrosis of the femoral head (ONFH) using MALDI MSI.

Osteonecrosis of the femoral head (ONFH) is a common orthopedic disease characterized by disability and deformity. To better understand ONFH at molecular level and to explore the possibility of early diagnosis, instead of diagnosis based on macroscopic spatial characteristics, a matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) method was developed for ONFH disease for the first time. The most challenging step for ONFH MSI is to deal with human bone tissues which are much harder than the other biological samples studied by the reported MSI studies. In this work, the MSI sectioning method of hard bone tissues was established using tender acids and a series of test criteria. Small-molecule metabolites, such as lipids and amino acids, were detected in bone sections, realizing the in situ detection of spatial distribution of biometabolites.By comparing the distribution of metabolites from different regions of normal femoral head, ONFH bone tissue (ONBT), and adjacent ONFH bone tissue (ANBT), the whole process of femoral head from normal stage to necrosis was monitored and visualized at molecular level. Moreover, this developed MSI method was used for metabolomics study of ONFH. 72 differential metabolites were identified, suggesting that disturbances in energy metabolism and lipid metabolism affected the normal life activities of osteoblasts and osteoclasts. This study provides new perspectives for future pathological studies of ONFH.

Study on the chemical composition of Gegen-Tianma decoction and its absorbed constituents in rat plasma, brain based on UPLC-Q-TOF-MS and DESI-MSI

In traditional Chinese medicinal practices, Gegen (GG) and Tianma (TM) are widely utilized for headache relief, but their material basis has not been comprehensively characterized. This research utilized ultra performance liquid chromatography-quadrupole-time of flight-mass spectrometry (UPLC-Q-TOF-MS) for precise determination of Gegen-Tianma's (GGTM) material composition, and employed desorption electrospray ionization-mass spectrometry imaging (DESI-MSI) to pinpoint the brain-absorbed components and various metabolites post oral administration to rats. A total of 80 chemical constituents were identified from GGTM, 11 prototypes and 18 metabolites were identified from plasma. The brain tissue was identified in total 4 prototypes and 5 metabolites, these constituents were basically located in the prefrontal cortex and thalamus. The absorption patterns of components in the rat brain aligned with the varied distribution of metabolites within the brain. This study provides a solid theoretical basis for in-depth exploration of potential drug targets and elucidation of the specific mechanism of action of GGTM in the treatment of migraine.

The protective influence of Secamone emetica (Retz.) R. Br. ex Sm.: Mitigating oxidative stress and glycoxidation in glucose-albumin system

The science and processes of anti-glycoxidation are integral for exploring novel approaches to address health concerns. The study examines the sustainable utilization of wild edibles, Secamone emetica, as a strategic solution to address health concerns and strengthen food security. A step-by-step attenuation method in a glucose-induced glycation system was used to study the impact of phytochemical content and antioxidant capabilities on glycoxidation. The distribution of metabolites and antioxidants adheres to a pattern of stem > root > leaf. The extracts effectively reduce protein carbonyls [86.45 % SSE (Stem extract of S. emetica), 84.97 % RSE (Root extract of S. emetica), 57.34 % LSE (Leaf extract of S. emetica) vs. 53.74 % in AGEs (Advanced glycation end products)] and inhibit amyloid β-aggregation (88.64 % SSE, 84.86 % RSE, 82.70 % LSE vs. 53.74 % in AGEs). Electrophoretic mobility significantly increased (9.99 × 10–5 cm2/V.s in SSE), surpassing the negative control (7.78 × 10‐5 cm2/V.s in AGEs after 72 h). Thiol group concentrations are maintained and lower 5-hydroxymethylfurfural (HMF) impurities are observed, indicating anti-glycoxidative properties. These results are comparable to aminoguanidine, suggesting the extracts scavenge free radicals and inhibit glycoxidation's consequences. Thus, highlighting the biological capacity of S. emetica in addressing oxidative stress and glycoxidation underscores its potential benefits.

MALDI-2-Enabled Oversampling for the Mass Spectrometry Imaging of Metabolites at Single-Cell Resolution.

Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) can provide valuable insights into the metabolome of complex biological systems such as organ tissues and cells. However, obtaining metabolite data at single-cell spatial resolutions presents a few technological challenges. Generally, spatial resolution is defined by the increment the sample stage moves between laser ablation spots. Stage movements less than the diameter of the focused laser beam (i.e., oversampling) can improve spatial resolution; however, such oversampling conditions result in a reduction in sensitivity. To overcome this, we combine an oversampling approach with laser postionization (MALDI-2), which allows for both higher spatial resolution and improved analyte ionization efficiencies. This approach provides significant enhancements to sensitivity for various metabolite classes (e.g., amino acids, purines, carbohydrates etc.), with mass spectral intensities from 6 to 8 μm pixel sizes (from a laser spot size of ∼13 μm) being commensurate with or higher than those obtained by conventional MALDI at 20 μm pixel sizes for many different metabolites. This technique has been used to map the distribution of metabolites throughout mouse spinal cord tissue to observe how metabolite localizations change throughout specific anatomical regions, such as those distributed to the somatosensory area of the dorsal horn, white matter, gray matter, and ventral horn. Furthermore, this method is utilized for single-cell metabolomics of human iPSC-derived astrocytes at 10 μm pixel sizes whereby many different metabolites, including nucleotides, were detected from individual cells while providing insight into cellular localizations.

Alterations in the gut microbiome and metabolism profiles reveal the possible molecular mechanism of renal injury induced by hyperuricemia in a mouse model of renal insufficiency

Objectives: To investigate the role of the intestinal flora and metabolites in the development of hyperuricemic renal injury in chronic kidney disease (CKD).Methods: Unilaterally nephrectomized mice were fed with adenine and potassium oxonate for 9 weeks. HE staining combined with plasma biochemical indicators was used to evaluate renal pathological and functional changes. We conducted 16S rRNA sequencing and untargeted metabolomics on feces and plasma samples to reveale changes in intestinal microbiota and metabolites.Result: Our analysis revealed significant differences in 15 bacterial genera, with 7 being upregulated and 8 being downregulated. Furthermore, metabolomic analysis revealed changes in the distribution of amino acid and biotin metabolites in basic metabolic pathways in both feces and serum. Specifically, differentially abundant metabolites in feces were associated primarily with histidine metabolism; the biosynthesis of phenylalanine, tyrosine, and tryptophan; and tyrosine metabolism. In plasma, the differentially abundant metabolites were involved in multiple metabolic pathways, including aminoacyl-tRNA biosynthesis; glycine, serine, and threonine amino acid metabolism; valine, leucine, and isoleucine biosynthesis; tyrosine biosynthesis and metabolism; biotin metabolism; and taurine and hypotaurine metabolism. Furthermore, correlation analysis revealed that Akkermansia, UCG-005, Lachnospiraceae_NK4A136_group, Lactococcus, and Butymonas were associated with various differentially abundant metabolites as well as renal function, oxidative stress, and mitophagy. The changes in the intestinal flora observed in hyperuricemia may lead to imbalances in amino acid and biotin metabolism in both the intestine and host, ultimately affecting oxidative stress and mitophagy in mice and accelerating the progression of CKD.Conclusion: Our findings provide insights into a potential pathogenic mechanism by which hyperuricemia exacerbates renal injury in mice with renal insufficiency. Understanding these pathways may offer new therapeutic strategies for managing hyperuricemic renal injury in CKD patients.

Determination of Anthropogenic Pollutants in Adipose Tissue of the Caspian Seal Pusa caspica Gmelin, 1788 by High-Resolution Accurate Mass Spectrometry.

Tissue contamination with persistent organic pollutants (POPs) in organisms proved possible to comprehensively characterize in a single test by combining gas chromatography and high-resolution accurate mass spectrometry. Adipose tissue samples were collected from two Caspian seals (Pusa caspica Gmelin, 1788) found dead on the Caspian Sea shore in 2020. Organochlorine pesticides, primarily DDT and HCH, and polychlorinated biphenyls (PCBs) were major pollutants found in the Caspian seals. The distribution of metabolites indicated the absence of recent pesticide use. The PCB content was relatively high, but still at the lower limit of the range of values determined previously, as was also the case with pesticides. Chlordanes, polychlorinated naphthalenes, and polybrominated diphenyl ethers were detected in minor quantities and were therefore not considered to be major pollutants of the Caspian seal. The pollutant levels were below a threshold at which a distinct effect on seal health can be expected. High-resolution accurate mass (HRAM) spectrometry was found to provide a convenient tool for both targeted and nontargeted analyses of a wide range of organic pollutants in a single experiment.

Novel mimetic tissue standards for precise quantitative mass spectrometry imaging of drug and neurotransmitter concentrations in rat brain tissues.

Understanding the relationship between the concentration of a drug and its therapeutic efficacy or side effects is crucial in drug development, especially to understand therapeutic efficacy in central nervous system drug, quantifying drug-induced site-specific changes in the levels of endogenous metabolites, such as neurotransmitters. In recent times, evaluation of quantitative distribution of drugs and endogenous metabolites using matrix-assisted laser desorption/ionization (MALDI)-mass spectrometry imaging (MSI) has attracted much attention in drug discovery research. However, MALDI-MSI quantification (quantitative mass spectrometry imaging, QMSI) is an emerging technique, and needs to be further developed for practicable and convenient use in drug discovery research. In this study, we developed a reliable QMSI method for quantification of clozapine (antipsychotic drug) and dopamine and its metabolites in the rat brain using MALDI-MSI. An improved mimetic tissue model using powdered frozen tissue for QMSI was established as an alternative method, enabling the accurate quantification of clozapine levels in the rat brain. Furthermore, we used the improved method to evaluate drug-induced fluctuations in the concentrations of dopamine and its metabolites. This method can quantitatively evaluate drug localization in the brain and drug-induced changes in the concentration of endogenous metabolites, demonstrating the usefulness of QMSI.

Spatial Mapping of Bioactive Metabolites in the Roots of Three Bupleurum Species by Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging.

Bupleurum is a kind of medicinal plant that has made a great contribution to human health because of the presence of bioactive metabolites: Bupleurum saikosaponins and flavonoids. Despite their importance, it has been a challenge to visually characterize the spatial distribution of these metabolites in situ within the plant tissue, which is essential for assessing the quality of Bupleurum. The development of a new technology to identify and evaluate the quality of medicinal plants is therefore necessary. Here, the spatial distribution and quality characteristics of metabolites of three Bupleurum species: Bupleurum smithii (BS), Bupleurum marginatum var. stenophyllum (BM), and Bupleurum chinense (BC) were characterized by Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI). Twenty-nine metabolites, including saikosaponins, non-saikosaponins, and compounds from the saikosaponin synthesis pathway, were characterized. Some of these were successfully localized and visualized in the transverse section of roots. In these Bupleurum species, twelve saikosaponins, five non-saikosaponins, and five saikosaponin synthesis pathway compounds were detected. Twenty-two major influencing components, which exhibit higher ion intensities in higher quality samples, were identified as potential quality markers of Bupleurum. The final outcome indicates that BC has superior quality compared to BS and BM. MALDI-MSI has effectively distinguished the quality of these Bupleurum species, providing an intuitive and effective marker for the quality control of medicinal plants.

Metabolic profiling and spatial metabolite distribution in wild soybean (G. soja) and cultivated soybean (G. max) seeds

Wild soybeans retain many substances significantly reduced or lost in cultivars during domestication. This study utilized LC-MS to analyze metabolites in the seed coats and embryos of wild and cultivated soybeans. 866 and 815 metabolites were identified in the seed extracts of both soybean types, with 35 and 10 significantly differing metabolites in the seed coat and embryos, respectively. The upregulated metabolites in wild soybeans are linked to plant defense, stress responses, and nitrogen cycling. MALDI-MSI results further elucidated the distribution of these differential metabolites in the cotyledons, hypocotyls, and radicles. In addition to their role in physiological processes like growth and response to environmental stimuli, the prevalent terpenoids, lipids, and flavonoids present in wild soybeans exhibit beneficial bioactivities, including anti-inflammatory, antibacterial, anticancer, and cardiovascular disease prevention properties. These findings underscore the potential of wild soybeans as a valuable resource for enhancing the nutritional and ecological adaptability of cultivated soybeans.

Visualization of metabolite distribution based on matrix-assisted laser desorption/ionization-mass spectrometry imaging of tea seedlings (Camellia sinensis).

Tea seedlings (Camellia sinensis) have a well-developed root system with a strong taproot and lateral roots. Compared with ordinary cuttings, tea has stronger vitality and environmental adaptability, thus facilitating the promotion of good varieties. However, there is less of detailed research on the rooting and germination process of tea seeds. In this study, matrix-assisted laser desorption ionization time-of-flight-mass spectrometry was used to conduct non-targeted spatial mass spectrometry imaging of the main organs during growth of tea seedlings. A total of 1234 compounds were identified, which could be divided into 24 classes. Among them, theanine, as the most prominent nitrogen compound, was synthesized rapidly at the early stage of embryo germination, accounting for >90% of the total free amino acids in the radicle, and it was then transferred to each meristem region through the mesocolumnar sheath, indicating that theanine-based nitrogen flow plays a decisive role in organ formation during the development of tea seedlings. Nutrients stored in the cotyledon were rapidly hydrolyzed to dextrin and 3-phosphoglyceraldehyde at the early stages of germination, and subsequently converted to other forms that provided carbon and energy for development, such as raffinose and d-galactose (glucose), which were mainly distributed in the growing zones of the root apex and the apical meristems of the stem. This study provides a new perspective on the synthesis and metabolism of substances during the development of tea seedlings and contributes to a better understanding of the biological characteristics of tea varieties.

RhizoMAP: a comprehensive, nondestructive, and sensitive platform for metabolic imaging of the rhizosphere

BackgroundElucidating the intricate structural organization and spatial gradients of biomolecular composition within the rhizosphere is critical to understanding important biogeochemical processes, which include the mechanisms of root-microbe interactions for maintaining sustainable plant ecosystem services. While various analytical methods have been developed to assess the spatial heterogeneity within the rhizosphere, a comprehensive view of the fine distribution of metabolites within the root-soil interface has remained a significant challenge. This is primarily due to the difficulty of maintaining the original spatial organization during sample preparation without compromising its molecular content.ResultsIn this study, we present a novel approach, RhizoMAP, in which the rhizosphere molecules are imprinted on selected polymer membranes and then spatially profiled using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI). We enhanced the performance of RhizoMAP by combining the use of two thin (< 20 μm) membranes (polyester and polycarbonate) with distinct MALDI sample preparations. This optimization allowed us to gain insight into the distribution of over 500 different molecules within the rhizosphere of poplar (Populus trichocarpa) grown in rhizoboxes filled with mycorrhizae soil. These two membranes, coupled with three different sample preparation conditions, enabled us to capture the distribution of a wide variety of molecules that included phytohormones, amino acids, sugars, sugar glycosides, polycarboxylic acids components of the Krebs cycle, fatty acids, short aldehydes and ketones, terpenes, volatile organic compounds, fertilizers from the soil, and others. Their spatial distribution varies greatly, with some following root traces, others showing diffusion from roots, some associated with soil particles, and many having distinct hot spots along the plant root or surrounding soil. Moreover, we showed how RhizoMAP can be used to localize the origin of the molecules and molecular transformation during root growth. Finally, we demonstrated the power of RhizoMAP to capture molecular distributions of key metabolites throughout a 20 cm deep rhizosphere.ConclusionsRhizoMAP is a method that provides nondestructive, untargeted, broad, and sensitive metabolite imaging of root-associated molecules, exudates, and soil organic matter throughout the rhizosphere, as demonstrated in a lab-controlled native soil environment.

Mapping small metabolite changes after traumatic brain injury using AP-MALDI MSI

Traumatic brain injury (TBI) is an alteration of brain function caused by a sudden transmission of an external force to the head. The biomechanical impact induces acute and chronic metabolic changes that highly contribute to injury evolution and outcome. TBI heterogeneity calls for approaches allowing the mapping of regional molecular and metabolic changes underpinning disease progression, with mass spectrometry imaging (MSI) as an efficient tool to study the spatial distribution of small metabolites. In this study, we applied an innovative targeted atmospheric pressure-MALDI mass spectrometry imaging (AP-MALDI MSI) approach, starting from an extensive list of metabolites, representative of different metabolic pathways, individually validated on the tissue under analysis with original standards using 2,5-dihydroxybenzoic acid (DHB), to characterize the impact of TBI on regional changes to small metabolites in the brain. Brains from sham and TBI mice obtained 21 days post-injury were analyzed to examine the spatial metabolic profile of small metabolites belonging to different metabolic pathways. By a whole brain analysis, we identified four metabolites (alanine, lysine, histidine, and inosine) with higher abundance in TBI than sham mice. Within the TBI group, lysine, histidine, and inosine were higher in the hemisphere ipsilateral to the biomechanical impact vs. the contralateral one. Images showed a major involvement of the ipsilateral thalamus characterized by the increase of arginine, lysine, histidine, and inosine and a significant reduction of glutamic acid, and N-acetylaspartic acid compared to the contralateral thalamus. These findings indicate high-resolution imaging mass spectrometry as a powerful tool to identify region-specific changes after a TBI to understand the metabolic changes underlying brain injury evolution.