Children with Hirschsprung disease exhibited alterations in host-microbial co-metabolism after pull-through operation.

PURPOSE: This study aims to compare the fecal metabolome in post pull-through HD with and without HAEC patients and healthy young children using nuclear magnetic resonance (NMR) spectroscopy. METHODS: Fresh fecal samples were collected from children under 5 years of age in both post-pull-through HD patients and healthy Thai children. A total of 20 fecal samples were then analyzed using NMR spectroscopy. RESULTS: Thirty-four metabolites identified among HD and healthy children younger than 5 years were compared. HD samples demonstrated a significant decrease in acetoin, phenylacetylglutamine, and N-acetylornithine (corrected p value = 0.01, 0.04, and 0.004, respectively). Succinate and xylose significantly decreased in HD with HAEC group compared to HD without HAEC group (corrected p value = 0.04 and 0.02, respectively). Moreover, glutamine and glutamate metabolism, and alanine, aspartate, and glutamate metabolism were the significant pathways involved, with pathway impact 0.42 and 0.50, respectively (corrected p value = 0.02 and 0.04, respectively). CONCLUSION: Differences in class, quantity, and metabolism of protein and other metabolites in young children with HD after pull-through operation were identified. Most of the associated metabolic pathways were correlated with the amino acids metabolism, which is required to maintain intestinal integrity and function.

Comparative analysis of bile metabolic profile in patients with biliary obstruction complicated by Clonorchis sinensis infection.

Background: Clonorchiasis is an important foodborne parasitic disease. However, eggs of Clonorchis sinensis (C. sinensis) cannot be detected in feces during biliary obstruction. Moreover, many diseases can cause biliary obstruction, such as gallstones, adenocarcinoma, cholangiocarcinoma and Ascaris lumbricoides infection. Therefore, it is of great significance to distinguish between patients of biliary obstruction and biliary obstruction with C. sinensis infection. Methods: A total of 48 biliary obstruction patients were enrolled, including 23 infected with C. sinensis (C. sinensis) (OB+C.s) and 25 non-infected subjects (OB). The bile samples were collected by endoscopic retrograde cholangiopancreatography and analyzed using ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QTOF MS). Additionally, multivariate statistical analysis methods were employed to identify differential metabolites. Next, bile amino acid levels were determined by targeted metabolomics analysis. Result: A total of 146 and 132 significant metabolites were identified in electrospray ionization (ESI)+ and ESI- modes, respectively. The levels of amino acids (asparagine, glutamate, ornithine) and polyamines (spermidine and spermine) were significantly changed. Targeted analysis showed that the levels of amino acids (such as L-arginine, L-glutamine, L-lysine, L-propionic, and L-tyrosine) were lower in OB+C.s patients compared to those in OB patients. Marked metabolic pathways were involved in "Glutathione metabolism", "Caffeine metabolism", "Alanine, aspartate and glutamate metabolism", "Arginine and proline metabolism", "Purine metabolism", "Beta-Alanine metabolism", and "D-glutamine and D-glutamate metabolism". Conclusion: These results show that there were significant differences between OB+C.s and OB patients, especially in amino acids. The metabolic signature and perturbations in metabolic pathways may help to better distinguish OB+C.s and OB patients.

Pyruvate Kinase M (PKM) binds ribosomes in a poly-ADP ribosylation dependent manner to induce translational stalling.

In light of the numerous studies identifying post-transcriptional regulators on the surface of the endoplasmic reticulum (ER), we asked whether there are factors that regulate compartment specific mRNA translation in human cells. Using a proteomic survey of spatially regulated polysome interacting proteins, we identified the glycolytic enzyme Pyruvate Kinase M (PKM) as a cytosolic (i.e. ER-excluded) polysome interactor and investigated how it influences mRNA translation. We discovered that the PKM-polysome interaction is directly regulated by ADP levels-providing a link between carbohydrate metabolism and mRNA translation. By performing enhanced crosslinking immunoprecipitation-sequencing (eCLIP-seq), we found that PKM crosslinks to mRNA sequences that are immediately downstream of regions that encode lysine- and glutamate-enriched tracts. Using ribosome footprint protection sequencing, we found that PKM binding to ribosomes causes translational stalling near lysine and glutamate encoding sequences. Lastly, we observed that PKM recruitment to polysomes is dependent on poly-ADP ribosylation activity (PARylation)-and may depend on co-translational PARylation of lysine and glutamate residues of nascent polypeptide chains. Overall, our study uncovers a novel role for PKM in post-transcriptional gene regulation, linking cellular metabolism and mRNA translation.

Developmental changes of free amino acids in amniotic, allantoic fluids and yolk of broiler embryo.

1. A study was conducted to evaluate the developmental changes of protein and free amino acid concentrations in amniotic, allantoic fluids and yolk during the incubation period of broiler eggs.2. A total of 120 Cobb 500 fertile eggs were individually weighed and then placed in an incubator. On incubation day: 8, 11, 13, 14, 16, and/or 18, amniotic, allantoic fluids and yolk were collected from 20 eggs for analysis of protein content and free α-amino acid concentration in allantoic and amniotic fluids and yolk.3. The total protein concentration in amniotic fluid increased from d 11 of incubation, and reached a peak at d 16 (69.85 g/l; P < 0.01), then declined at d 18 (P < 0.05). The total protein concentration in allantoic fluid increased with age of the embryo (P < 0.01). Crude protein concentration in yolk decreased (P < 0.05) from d 0 to 8, then increased gradually from d 8, and reached a peak at d 16 (P < 0.05). The concentration of most free amino acids in amniotic and allantoic fluids and yolk was related to embryo weight. Amniotic fluid amino acids gradually increased from d 13 to 18, with arginine being the most abundant at d 11 and 14. Glutamate was the most predominant amniotic fluid amino acid at d 16 and 18. From d 13 to 18, the concentrations of most α-amino acids in allantoic fluid increased, and reached a peak at d 18 (aspartate, 373 µmol/l; asparagine, 519 µmol/l; glutamine, 1230 µmol/l; threonine, 537 µmol/l; citrulline, 112 µmol/l; arginine, 2747 µmol/l; alanine, 276 µmol/l; tyrosine, 330 µmol/l; tryptophan, 212 µmol/l; valine, 140 µmol/l; phenylalanine, 102 µmol/l; isoleucine, 92.39 µmol/l; lysine, 1088 µmol/l; P < 0.05). Glutamine was the second most abundant amino acid in allantoic fluid at d 13 and 18. Glutamate was the most abundant α-amino acids at d 8, and 13 in the yolk.4. These results demonstrated that the concentration of free α-amino acids in chicken embryo fluid was related to embryo weight. Arginine, glutamine and glutamate were abundant free α-amino acids in chicken embryo fluid, to support the higher rates of tissue protein synthesis and growth for the embryo.

Menghai Huangye, a novel albino tea germplasm with high theanine content and a high catechin index.

Yunnan Province has a very wide diversity of tea germplasm resources. A variety of special tea germplasms with outstanding traits have been discovered, including tea germplasms with high anthocyanin content and low caffeine content. Albino tea cultivars generally have higher contents of theanine that contribute to the umami taste, and the quality of tea brewed from it is higher. The catechin index (CI), the ratio of dihydroxylated catechins (DIC) to trihydroxylated catechins (TRIC), is a crucial index of suitability for processing tea. In this study, the albino tea plant Menghai Huangye (MHHY) with yellow leaves was identified. Analysis of the biochemical components revealed that MHHY was enriched in theanine and the total catechins (TC) were lower than Yunkang 10 (YK10). In addition, the CI value of MHHY was extremely significantly higher than that of YK10. Metabolic profile of catechins and the related gene expression profile analysis found that the coordinated expression of the key branch genes F3'H and F3'5'Ha for the synthesis of DIC and TRIC in tea plant was closely related to the high CI and low TC of MHHY. Further analysis of the F3'H promoter showed that a 284-bp deletion mutation was present in the F3'H promoter of MHHY, containing the binding sites of the transcriptional repressor MYB4 involved in flavonoid metabolism, which might be an important reason for the up-regulated expression of F3'H in MHHY. Overall, this study provides a theoretical basis for understanding the characteristics of albino tea germplasm resources and efficiently utilizing high-CI tea germplasm resources.

Foliar application of glycinebetaine and Zn fertilizer improves both the apparent and functional qualities of albino tea [Camellia sinensis (L.) O. Kuntze].

With Zn deficiency increasing in the global population, functional plant food (including tea) can help to fill the nutrition gap that the main crops cannot meet. Glycinebetaine (GB), an important bioactive substance with a wide range of natural sources, has received limited attention towards its effects on Zn biofortification and the quality of tea. The Zn enrichment and metabolite responses of albino tea [cv. White leaf No. 1 (WL-1)] to the foliar application of GB, Zn, and their combination (Zn + GB) were investigated in a field experiment. The result indicated that the 100-buds weight, total N, Zn, Thea, and total amino acid content in the young leaves of WL-1 with Zn2 + GB2 treatment were significantly increased, whereas the Chla contents were decreased (p < 0.05). The total catechins and CAF contents of Zn2 + GB2 treatment were lower than those of other treatments, with significance (p < 0.05). Multivariate analysis and general quantitative analysis returned complementary results, revealing that Zn2 + GB2 treatment was better for the apparent and functional quality of WL-1. The more theanine and Zn, limited chlorophyll, catechin, and caffeine contributed to the quality improvement, as well as to maintaining the leaf albinistic characteristics, inhibiting astringency and bitterness, exerting flavor and umami, and improving the ultimate beneficial functions. The combined application of Zn and GB is a promising practice for Zn biofortification and for the quality improvement of tea, with spraying 750 L ha-1 of 2.0 g L-1 Zn fertilizer and 3.2 g L-1 GB mixture recommended.

An In-vivo 1H-MRS short-echo time technique at 7T: Quantification of metabolites in chronic multiple sclerosis and neuromyelitis optica brain lesions and normal appearing brain tissue.

Magnetic Resonance Spectroscopy (MRS) allows for the non-invasive quantification of neurochemicals and has the potential to differentiate between the pathologically distinct diseases, multiple sclerosis (MS) and AQP4Ab-positive neuromyelitis optica spectrum disorder (AQP4Ab-NMOSD). In this study we characterised the metabolite profiles of brain lesions in 11 MS and 4 AQP4Ab-NMOSD patients using an optimised MRS methodology at ultra-high field strength (7T) incorporating correction for T2 water relaxation differences between lesioned and normal tissue. MS metabolite results were in keeping with the existing literature: total N-acetylaspartate (NAA) was lower in lesions compared to normal appearing brain white matter (NAWM) with reciprocal findings for myo-Inositol. An unexpected subtlety revealed by our technique was that total NAA differences were likely driven by NAA-glutamate (NAAG), a ubiquitous CNS molecule with functions quite distinct from NAA though commonly quantified together with NAA in MRS studies as total NAA. Surprisingly, AQP4Ab-NMOSD showed no significant differences for total NAA, NAA, NAAG or myo-Inositol between lesion and NAWM sites, nor were there any differences between MS and AQP4Ab-NMOSD for a priori hypotheses. Post-hoc testing revealed a significant correlation between NAWM Ins:NAA and disability (as measured by EDSS) for disease groups combined, driven by the AP4Ab-NMOSD group. Utilising an optimised MRS methodology, our study highlights some under-explored subtleties in MRS profiles, such as the absence of myo-Inositol concentration differences in AQP4Ab-NMOSD brain lesions versus NAWM and the potential influence of NAAG differences between lesions and normal appearing white matter in MS.

From Tea Leaves to Factories: A Review of Research Progress in l-Theanine Biosynthesis and Production.

l-Theanine is the most popular nonprotein amino acid contained in tea leaves. It is one of the umami components of green tea, contributing to the unique flavor of tea. Because of its various health functions, l-theanine has been commercially developed as a valuable ingredient easily used for various applications in food and pharmaceutical industries. Nowadays, l-theanine is mass-produced by plant extraction, chemical synthesis, or enzymatic transformation in factories. This review embodies the available up to date information on the l-theanine synthesis metabolism in the tea plant as well as approaches to produce it, placing emphasis on the biotransformation of l-theanine. It also gives insight into the challenges of l-theanine production on a large scale, as well as directions for future research. This review comprehensively summarizes information on l-theanine to provide an approach for an in-depth study of l-theanine production.

Characterization of L-theanine in tea extracts and synthetic products using stable isotope ratio analysis.

L-theanine involves a great number of health benefits and dietary supplements containing this molecule are becoming increasingly popular. There is, therefore, a growing need to find ways to discriminate between natural L-theanine extracted from tea leaves and the cheaper, synthetic one obtained using specific bacterial enzymes. A first attempt of stable isotope ratio analysis characterization of the possible synthetic adulterant L-theanine (δ13C of -14.3 ± 1.5‰), obtained from vegetable substrates with C4 photosynthetic cycle, and of the more expensive natural L-theanine (δ13C of -24.4 ± 1.3‰), extracted from Camellia sinensis plants with C3 photosynthetic cycle, is reported here.

Magnetic Resonance Spectroscopy following Mild Traumatic Brain Injury: A Systematic Review and Meta-Analysis on the Potential to Detect Posttraumatic Neurodegeneration.

INTRODUCTION: Traumatic brain injury (TBI) is the most relevant external risk factor for dementia and a major global health burden. Mild TBI (mTBI) contributes to up to 90% of all TBIs, and the classification "mild" often misrepresents the patient's burden who suffer from neuropsychiatric long-term sequelae. Magnetic resonance spectroscopy (MRS) allows in vivo detection of compromised brain metabolism although it is not routinely used after TBI. OBJECTIVE: Thus, we performed a systematic review and meta-analysis to elucidate if MRS has the potential to identify changes in brain metabolism in adult patients after a single mTBI with a negative routine brain scan (CCT and/or MRI scan) compared to aged- and sex-matched healthy controls (HC) during the acute or subacute postinjury phase (≤90 days after mTBI). METHODS: A comprehensive literature search was conducted from the first edition of electronic databases until January 31, 2020. Group analyses were performed per metabolite using a random-effects model. RESULTS: Four and 2 out of 5,417 articles met the inclusion criteria for the meta-analysis and systematic review, respectively. For the meta-analysis, 50 mTBI patients and 51 HC with a mean age of 31 and 30 years, respectively, were scanned using N-acetyl-aspartate (NAA), a marker for neuronal integrity. Glutamate (Glu), a marker for disturbed brain metabolism, choline (Cho), a marker for increased cell membrane turnover, and creatine (Cr) were used in 2 out of the 4 included articles. Regions of interests were the frontal lobe, the white matter around 1 cm above the lateral ventricles, or the whole brain. NAA was decreased in patients compared to HC with an effect size (ES) of -0.49 (95% CI -1.08 to 0.09), primarily measured in the frontal lobe. Glu was increased in the white matter in 22 mTBI patients compared to 22 HC (ES 0.79; 95% CI 0.17-1.41). Cho was decreased in 31 mTBI patients compared to 31 HC (ES -0.31; 95% CI -0.81 to 0.19). Cr was contradictory and, therefore, potentially not suitable as a reference marker after mTBI. CONCLUSIONS: MRS pinpoints changes in posttraumatic brain metabolism that correlate with cognitive dysfunction and, thus, might possibly help to detect mTBI patients at risk for unfavorable outcome or posttraumatic neurodegeneration early.

The Biosynthesis of Main Taste Compounds Is Coordinately Regulated by miRNAs and Phytohormones in Tea Plant (Camellia sinensis).

Based on the abundance of taste compounds in leaves at different leaf positions on the same shoot, green tea made from one bud and one leaf, or even just one bud, has the best quality. To elucidate the mechanism underlying the regulation of the biosynthesis of these compounds, we profiled the metabolome, transcriptome, sRNA, degradome, and WGCNA using leaves from five leaf positions of shoots. Through this analysis, we found 139 miRNA-target pairs related to taste compound biosynthesis and 96 miRNA-target pairs involved in phytohormone synthesis or signal transduction. Moreover, miR166-HD-ZIP, miR169-NF-YA, IAA, ZA, ABA, and JA were positively related to the accumulation of gallated catechin, caffeine, and theanine. However, miR396-GRF, miR393-bHLH, miR156-SBP, and SA were negatively correlated with these compounds. Among these important pairs, the miR396-GRF and miR156-SBP pairs were further validated by using qRT-PCR, Northern blots, and cotransformation. This is the first report describing that miRNA-TF pairs and phytohormones might synergistically regulate the biosynthesis of taste compounds in the leaves of tea plants.

In Vivo Chemical Analysis of Plant Sap from the Xylem and Single Parenchymal Cells by Capillary Microsampling Electrospray Ionization Mass Spectrometry.

In plants, long-distance transport of chemicals from source to sink takes place through the transfer of sap inside complex trafficking systems. Access to this information provides insight into the physiological responses that result from the interactions between the organism and its environment. In vivo analysis offers minimal perturbation to the physiology of the organism, thus providing information that represents the native physiological state more accurately. Here we describe capillary microsampling with electrospray ionization mass spectrometry (ESI-MS) for the in vivo analysis of xylem sap directly from plants. Initially, fast MS profiling was performed by ESI from the whole sap exuding from wounds of living plants in their native environment. This sap, however, originated from the xylem and phloem and included the cytosol of damaged cells. Combining capillary microsampling with ESI-MS enabled targeted sampling of the xylem sap and single parenchymal cells in the pith, thereby differentiating their chemical compositions. With this method we analyzed soybean plants infected by nitrogen-fixing bacteria and uninfected plants to investigate the effects of symbiosis on chemical transport through the sap. Infected plants exhibited higher abundances for certain nitrogen-containing metabolites in their sap, namely allantoin, allantoic acid, hydroxymethylglutamate, and methylene glutamate, compared to uninfected plants. Using capillary microsampling, we localized these compounds to the xylem, which indicated their transport from the roots to the upper parts of the plant. Differences between metabolite levels in sap from the infected and uninfected plants indicated that the transport of nitrogen-containing and other metabolites is regulated depending on the source of nitrogen supply.

Glutamate detection at the cellular level by means of polymer/enzyme multilayer modified carbon nanoelectrodes.

Carbon nanoelectrodes in the sub-micron range were modified with an enzyme cascade immobilized in a spatially separated polymer double layer system for the detection of glutamate at the cellular level. The enzyme cascade consists of glutamate oxidase (GlutOx) that was immobilized in a hydrophilic redox silent polymer on top of a horseradish peroxidase (HRP)/redox polymer layer. In the presence of O2, glutamate was oxidized under concomitant reduction of O2 to H2O2 at GlutOx. H2O2 is further reduced to water by means of HRP and electrons are shuttled via the redox polymer matrix that wires the HRP to the electrode surface, hence delivering a current response proportional to the glutamate concentration. The nanometer-sized sensors could be successfully used to measure glutamate release from primary mouse astrocytes in 10 mM HEPES buffer.

"Oral" tribology study on saliva-tea compound mixtures: Correlation between sweet aftertaste (Huigan) perception and friction coefficient.

Sweet aftertaste (Huigan) is a sensation perceived after drinking tea, and lasts in the mouth and throat, leading to salivation for an extended period of time. The study aimed to reveal the underpinning mechanisms of Huigan and the its influencing factors. Tribology approach was applied to this study in conjunction with sensory analysis and other physiology assessments. Tea compounds of commercial interest were selected for the study. Preliminary sensory tests of 24 subjects were carried out to evaluate the Huigan intensity of these tea compounds. Based on these tests, 12 subjects were selected and divided into two groups, each with 6 subjects: sensitive subjects and non-sensitive subjects. In vitro tribology measurements were made for samples prepared either prepared as 1:1 mixtures of tea compound solution and human whole saliva or expectorated tea compound solutions along with the saliva which were collected from the subjects after oral processing. The Huigan intensity perceived by the sensitive group was found to be highly correlated with the friction coefficient measured, especially at the sliding speeds lower than 0.5 mm/s.

Determination of N-Carbamylglutamate in Feeds and Animal Products by High Performance Liquid Chromatography Tandem Mass Spectrometry.

N-carbamylglutamate (NCG), a synthetic analogue of N-acetylglutamate, is an activator of blood ammonia conversion and endogenous arginine synthesis. Here, we established an accurate quantitative determination of NCG in feeds, animal tissues, and body fluids using the high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). The sample pretreatment procedures included extraction with 0.5% of formic acid in water/methanol (80/20, v/v), and purification using an anionic solid phase extraction cartridge. Satisfactory separation of NCG was achieved in 20 min with the application of an Atlantis T3 column, and a confirmative detection of NCG was ensured by multiple reaction monitoring of positive ions. NCG spiked in feeds, tissues, and body fluids were evaluated in regard to linearity, sensitivity, recovery, and repeatability. Recoveries for different sample matrices were in the range of 88.12% to 110.21% with relative standard deviations (RSDs) less than 8.8%. Limits of quantification were within the range of 0.012 to 0.073 mg kg-1 and 0.047 to 0.077 µg mL-1 for solid and liquid samples, respectively. This study will provide a solid foundation for the evaluation of availability and metabolic mechanism of NCG in animals.

Comparative Transcriptomic Analysis Reveals Regulatory Mechanisms of Theanine Synthesis in Tea (Camellia sinensis) and Oil Tea (Camellia oleifera) Plants.

Tea provides a rich taste and has healthy properties due to its variety of bioactive compounds, such as theanine, catechins, and caffeine. Theanine is the most abundant free amino acid (40%-70%) in tea leaves. Key genes related to theanine biosynthesis have been studied, but relatively little is known about the regulatory mechanisms of theanine accumulation in tea leaves. Herein, we analyzed theanine content in tea (Camellia sinensis) and oil tea (Camellia oleifera) and found it to be higher in the roots than in other tissues in both species. The theanine content was significantly higher in tea than oil tea. To explore the regulatory mechanisms of theanine accumulation, we identified genes involved in theanine biosynthesis by RNA-Seq analysis and compared theanine-related modules. Moreover, we cloned theanine synthase (TS) promoters from tea and oil tea plants and found that a difference in TS expression and cis-acting elements may explain the difference in theanine accumulation between the two species. These data provide an important resource for regulatory mechanisms of theanine accumulation in tea plants.

Untargeted metabolomics coupled with chemometrics analysis reveals potential non-volatile markers during oolong tea shaking.

Shaking is a critical process in the formation of oolong tea quality, although the metabolites and their changes in this sensitive process have not yet been determined. In this study, untargeted analysis based on ultrahigh-performance liquid chromatography/quadrupole-Orbitrap mass spectrometry was conducted to comprehensively profile metabolite changes in different cultivars. Theanine glucoside was identified for the first time in oolong tea. Hierarchical cluster analysis indicated that shaking caused major changes in metabolite levels in oolong tea. Seventy-one, 83 and 73 potential features showed significant differences between pre- and post-shaking samples for var. sinensiscv. "Zimudan", "Shuixian", and "Huangmeigui," respectively. Chemometrics analysis of the three cultivars led to the identification of 18 shared metabolites, including epigallocatechin gallate, phenylalanine, tryptophan, proline, and hydroxy-jasmonic acid, as potential markers. This study identified the metabolites that allow monitoring of tea quality formation during both processing and preservation, and it provides a novel strategy for data reduction in studies to discover key metabolites.

Analysis of Young Shoots of 'Anji Baicha' (Camellia sinensis) at Three Developmental Stages Using Nontargeted LC-MS-Based Metabolomics.

'Anji Baicha' (Camellia sinensis) is a low-temperature-sensitive tea variety. During the development of young shoots, the leaves of 'Anji Baicha' exhibit periodic albinism. The quality of 'Anji Baicha' is closely related to the color of the fresh leaves, with whiter leaves affording a higher amino acid content and superior sensory quality after processing. However, the metabolic mechanism of its quality formation is still unclear. In this study, we analyzed the metabolomic changes of young shoots of 'Anji Baicha' and screened for metabolic markers that may be involved in the periodic albinism. Positive- and negative-mode UPLC-QTOF-MS was applied to the metabolomic analysis of young leaves of 'Anji Baicha' during three developmental stages (i.e., the pre-albescent, albescent, and regreening stages). The results revealed significant differences in the metabolic profiles of the young leaves at the three stages. The differential metabolites were mainly related to the pathways of flavonoid, phenylpropanoid, and amino acid biosynthesis. The concentrations of several amino acids (primarily l-theanine, l-glutamate, N2 -acetyl-l-ornithine, l-aspartic acid, d-proline, l-glutamine, l-leucine, and pyroglutamic acid) and 12-OPDA were significantly higher in the albescent stage. In contrast, during the albescent stages, the concentrations of several carbohydrates (d-fructose, ß-d-galactopyranose, 3-O-fucopyranosyl-2-acetamido-2-deoxyglucopyranose, galactose-ß-1, 4-xylose acetyl-maltose, and 2-fucosyllactose) were significantly lower. Moreover, catechins (mainly epigallocatechin and catechin derivatives), dimeric catechins (primarily proanthocyanidins), and flavonol and flavonol/flavone glycosides (mainly kaempferol, myricetin, quercetin, cyanidin, and delphinidin glycosides) were detected at the highest levels in the regreening or pre-albescent stages. The obtained results enhance the current understanding of the metabolic mechanisms of periodic albinism and quality development formation in 'Anji Baicha'. PRACTICAL APPLICATION: The obtained results not only provide information regarding differential metabolites but also advance the understanding of the mechanism of periodic albinism in 'Anji Baicha' at the metabolite level and open up new possibilities for the genetic improvement of tea cultivars.

Effect of Major Tea Insect Attack on Formation of Quality-Related Nonvolatile Specialized Metabolites in Tea ( Camellia sinensis) Leaves.

Insect attack is known to induce a high accumulation of volatile metabolites in tea ( Camellia sinensis). However, little information is available concerning the effect of insect attack on tea quality-related nonvolatile specialized metabolites. This study aimed to investigate the formation of characteristic nonvolatile specialized metabolites in tea leaves in response to attack by major tea insects, namely, tea green leafhoppers and tea geometrids, and determine the possible involvement of phytohormones in metabolite formation resulting from insect attack. Both tea green leafhopper and tea geometrid attacks increased the jasmonic acid and salicylic acid contents. The abscisic acid content was only increased under tea green leafhopper attack, perhaps due to special continuous piercing-sucking wounding. Tea green leafhopper attack induced the formation of theaflavins from catechins under the action of polyphenol oxidase, while tea geometrid attack increased the l-theanine content. Exogenous phytohormone treatments can affect the caffeine and catechin contents. These results will help to determine the influence of major tea pest insects on important tea quality-related metabolites and enhance understanding of the relationship of phytohormones and quality-related nonvolatile metabolite formation in tea exposed to tea pest insect attacks.

Visualized analysis of within-tissue spatial distribution of specialized metabolites in tea (Camellia sinensis) using desorption electrospray ionization imaging mass spectrometry.

Although specialized metabolite distributions in different tea (Camellia sinensis) tissues has been studied extensively, little is known about their within-tissue distribution owing to the lack of nondestructive methodology. In this study, desorption electrospray ionization imaging mass spectrometry was used to investigate the within-tissue spatial distributions of specialized metabolites in tea. To overcome the negative effects of the large amount of wax on tea leaves, several sample preparation methods were compared, with a Teflon-imprint method established for tea leaves. Polyphenols are characteristic metabolites in tea leaves. Epicatechin gallate/catechin gallate, epigallocatechin gallate/gallocatechin gallate, and gallic acid were evenly distributed on both sides of the leaves, while epicatechin/catechin, epigallocatechin/gallocatechin, and assamicain A were distributed near the leaf vein. L-Theanine was mainly accumulated in tea roots. L-Theanine and valinol were distributed around the outer root cross-section. The results will advance our understanding of the precise localizations and in-vivo biosyntheses of specialized metabolites in tea.