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Background and Purpose: Given the overlapping clinical manifestations and pathology, the differentiation between essential tremor (ET) and Parkinson's disease (PD) is difficult. Our aims were to examine the plasma metabolomics profiling and their association with motor and non-motor symptoms (NMS) in patients with PD, and to determine differences between de novo PD compared to moderate-advanced PD vs. controls and patients with ET.Methods: Plasma samples were collected from 137 subjects including 35 age matched controls, 29 NOVO-PD, 35 PD and 38 ET patients. PD severity, motor and NMS including cognitive function were assessed using the UPDRS, NMS and PD cognitive rating scales, respectively. Metabolomics analysis was performed by UPLC-ESI-QToF-MS followed by unsupervised multivariate statistics. The area under the curve of the biomarkers according to distribution of their concentrations and the diagnosis of PD (NOVO-PD, advanced PD) vs ET and healthy controls was used as a measurement of diagnostic ability.Results: Several acyl-carnitines, bilirubin, tyramine and tetrahydro-21-deoxycortisol (THS) presented good predictive accuracy (AUC higher than 0.8) for differentiating de novo PD and advanced PD from controls and ET, suggesting an alteration in the lipid oxidation pathway. In multivariate regression analysis, metabolite levels were not significantly associated with motor and NMS severity in PD.Conclusions: Diverse acyl-carnitines, bilirubin, tyramine and some adrenal gland derived metabolites are suggested as potential biomarkers able to distinguish between PD from controls and ET. [ABSTRACT FROM AUTHOR]

Biogenic amines in dairy products such as pasteurized milk, gluten-free and lactose-free milk, lactose-free milk, milk cream, yoghurt, kefir, cottage cheese, kasar cheese, tulum cheese and kuflu cheese were evaluated by using liquid chromatography (HPLC) technique and compared in detail with literature. The HPLC method used for the separation of biogenic amines has been validated in terms of suitability, linearity, accuracy and sensitivity. For the used reversed-phase high-performance liquid chromatography method, the linearity were investigated in the concentration ranges of 0.01–10 mg/L (R2 = 0.996–0.999) for all biogenic amines. Mean recoveries for all biogenic amines ranged from 95 to 100.7%. The limits of detection and quantification were 6.13 × 10−4–3.22 × 10−3 mg/L and 2.04 × 10−3–1.07 × 10−2 mg/L, respectively. Tyramine, putrescine and spermine were detected in all products while other types were not determined in some products. The total amount of biogenic amines in pasteurized milk (12.48–19.82 mg/kg) were higher than both gluten-free and lactose-free milk (11.64 mg/kg) and lactose-free milk (8.65–10.33 mg/kg). It has been observed that the amount of tyramine and sermine in kefir and yoghurt products were similar. While cottage, kasar and tulum cheese products contained higher amount of tyramine compared to other biogenic amines, kuflu cheese was possessed of cadaverine. Although the types and amounts of biogenic amines in dairy products in Turkey were examined in many previous studies, it was evaluated in detail and combined in this study. In addition, gluten-free and lactose-free milk, lactose-free milk, milk cream and kuflu cheese were evaluated for the first time. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A detailed UPLC-ESI-MS study was performed on secondary metabolites in the biomass of a suspension plant cell culture of Turkmenian mandrake (Mandragora turcomanica Mizgir.), which has been maintained for over 30 years. Both compounds widespread in plants (amides of hydroxycinnamic acids with putrescine and feruloyltyramine) and very rare metabolites (glycosides of phenylethylamides of hydroxycinnamic acids) have been identified. The identification of compounds was carried out using ultra-performance liquid chromatography combined with high-resolution mass spectrometry with electrospray ionization (UPLC-ESI-MS) and detection of positive and negative ion modes. Structural analysis of glycosides of phenylethylamides of ferulic acid was carried out on the basis of interpreting MS spectra obtained by fragmentation of protonated molecular ions [M + H]+ of these compounds in the ionization source. Based on the obtained results, the presence of five hexosides of ferulic acid, three of which were with tyramine residues and one each with methoxytyramine and octopamine residues, respectively, in the M. turcomanica cells cultivated in vitro was revealed. One of the detected glycosides belongs to a very rare group of plant metabolites: feruloyltyramine dihexosides. The obtained results confirm the concept developed in the authors' works on the change in specialized metabolism of plant cells cultivated in vitro and indicate that dedifferentiated proliferating cells retain the ability to form a complex set of secondary metabolites, which contradicts the prevailing ideas about the loss or decrease in the intensity of specialized metabolism in plant cell cultures. [ABSTRACT FROM AUTHOR]

A new tyramine derivative, glycosamide A (1), together with two known amide alkaloids, N-benzoyltyramine methyl ether (2) and aurantiamide acetate (3), was isolated from the branches and leaves of Glycosmis craibii Tanaka. Their structures were elucidated through extensive 1D and 2D NMR and HR-ESI-MS spectroscopic analyses. All known compounds were isolated from the genus Glycosmis for the first time. Furthermore, the antiproliferative activities of all isolated alkaloids in vitro were evaluated. Compound 2 displayed weak antiproliferative activities against five human cancer cell lines, HL-60, SMMC-7721, A-549, MCF-7, and SW480. [ABSTRACT FROM AUTHOR]

This study investigated the positive effects of complete replacement of nitrite with a Lactobacillus fermentum on the quality and safety of Chinese fermented sausages, and evaluated the risk of this strain. The effects of the strain on pH, color, nitrite, thiobarbituric acid reactive substances (TBARS), total volatile basenitrogen (TVB-N), metmyoglobin (Met-Mb), biological amines, free amino acid content, and sensory index have been studied. The results revealed that the strain reduced the pH of the sausages, which reduced the risk of food-borne pathogens, and accelerated the acidification and gelation process. The inoculation of the strain produced pink color similar to 50 mg/kg nitrite, significantly reducing the residual risk of nitrite in the sausages. In addition, the strain effectively improved quality and nutrition of the sausages through preventing fat oxidation, protein decomposition, and myoglobin oxidation and increasing free amino acid content. The harmful biogenic amines species of the treated sample were reduced, although the tyramine contents were higher than the control, and the contents of the two groups were all far below the specified limit (800 mg/kg). The sensory analysis showed that the strain enhanced the taste, flavor, sourness, and overall acceptability of the sample sausages. Therefore, replacing nitrite completely with the strain L. fermentum could be a potential strategy to produce healthier and safer acceptable sausages through decreasing the risk of nitrite and improving nutrition and quality of the sausages. [ABSTRACT FROM AUTHOR]

The toxicity and addictive liability associated with cocaine abuse are well-known. However, its mode of action is not completely understood, and effective pharmacotherapeutic interventions remain elusive. The cholinergic effects of cocaine on acetylcholine receptors, synthetic enzymes, and degradative enzymes have been the focus of relatively little empirical investigation. Due to its genetic tractability and anatomical simplicity, the egg laying circuit of the hermaphroditic nematode, Caenorhabditis elegans, is a powerful model system to precisely examine the genetic and molecular targets of cocaine in vivo. Here, we report a novel cocaine-induced behavioral phenotype in C. elegans, cocaine-stimulated egg laying. In addition, we present the results of an in vivo candidate suppression screen of synthetic enzymes, receptors, degradative enzymes, and downstream components of the intracellular signaling cascades of the main neurotransmitter systems that control C. elegans egg laying. Our results show that cocaine-stimulated egg laying is dependent on acetylcholine synthesis and synaptic release, functional nicotinic acetylcholine receptors, and the C. elegans acetylcholinesterases. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC), as one of the most lethal cancers, significantly impacts human health. Attempts in this area tends to develop novel technologies with sensitive and multiplexed detection properties for early diagnosis. Here, we present novel hydrogel photonic crystal (PhC) barcodes with tyramine deposition amplified enzyme-linked immunosorbent assay (ELISA) for highly sensitive and multiplexed HCC biomarker screening. Because of the abundant amino groups of acrylic acid (AA) component, the constructed hydrogel PhC barcodes with inverse opal structure could facilitate the loading of antibody probes for subsequent detection of tumor markers. By integrating tyramine deposition amplified ELISA on the barcode, the detection signal of tumor markers has been enhanced. Based on these features, it is demonstrated that the hydrogel PhC barcodes with tyramine deposition amplified ELISA could realize highly sensitive and multiplexed detection of HCC-related biomarkers. It was found that this method is flexible, sensitive and accurate, suitable for multivariate analysis of low abundance tumor markers and future cancer diagnosis. These features make the newly developed PhC barcodes an innovation platform, which possesses tremendous potential for practical application of low abundance targets. [ABSTRACT FROM AUTHOR]

Inflammatory bowel disease (IBD) is characterized by dysbiosis of the gut microbiota and dysfunction of intestinal stem cells (ISCs). However, the direct interactions between IBD microbial factors and ISCs are undescribed. Here, we identify α 2A -adrenergic receptor (ADRA2A) as a highly expressed GPCR in ISCs. Through PRESTO-Tango screening, we demonstrate that tyramine, primarily produced by Enterococcus via tyrosine decarboxylase (tyrDC), serves as a microbial ligand for ADRA2A. Using an engineered tyrDC -deficient Enterococcus faecalis strain and intestinal epithelial cell-specific Adra2a knockout mice, we show that Enterococcus -derived tyramine suppresses ISC proliferation, thereby impairing epithelial regeneration and exacerbating DSS-induced colitis through ADRA2A. Importantly, blocking the axis with an ADRA2A antagonist, yohimbine, disrupts tyramine-mediated suppression on ISCs and alleviates colitis. Our findings highlight a microbial ligand-GPCR pair in ISCs, revealing a causal link between microbial regulation of ISCs and colitis exacerbation and yielding a targeted therapeutic approach to restore ISC function in colitis. [Display omitted] • Tyramine is a microbial ligand of α 2A -adrenergic receptor (ADRA2A) in ISCs • Enterococcus -derived tyramine suppresses ISC proliferation and exacerbates colitis • Enterococcus , tyramine, and ADRA2A are enriched in geographically distinct IBD cohorts • ADRA2A antagonist yohimbine disrupts the suppression on ISCs and alleviates colitis The direct interactions between microbial factors and intestinal stem cells (ISCs) in inflammatory bowel disease are poorly understood. Li et al. now reveal that Enterococcus -derived tyramine hijacks α 2A -adrenergic receptor (ADRA2A) in ISCs to suppress ISC proliferation and exacerbate colitis. ADRA2A antagonist yohimbine disrupts the ISC suppression and alleviates colitis. [ABSTRACT FROM AUTHOR]

This study investigated bacterial compositions and their contributions to biogenic amine (BA) formation in Cheonggukjang using metagenomic and culturomic analyses. Metagenomic analysis revealed Bacillus spp. as dominant (96.19%), of which B. piscis (74.79%) and B. hisashii (19.39%) were predominant. Based on the relative abundance of BA-associated genes, B. piscis showed the highest correlations with tyrosine (R2 = 0.76) and lysine decarboxylation (R2 = 0.50), and B. hisashii with histidine decarboxylation (R2 = 0.42). Meanwhile, culturomic analysis revealed that, among mesophilic bacteria, Bacillus spp. were dominant (98.78%). As lactic acid bacteria (LAB), only Enterococcus spp. were detected. Of halotolerant LAB, Enterococcus spp. were dominant (90.72%). Based on in vitro BA productivity of all bacterial strains, Enterococcus spp. contributed primarily to tyramine formation. Thus, it was observed that the bacterial compositions and their contributions to BA formation determined using the two analyses differed considerably. To verify such observations, Cheonggukjang fermentation experiments were conducted using Bacillus and Enterococcus strains. The tyramine content was higher in the Bacillus -fermented samples (over 120.00 ± 14.18 mg/kg) than in the Enterococcus -fermented sample (34.24 ± 3.37 mg/kg). However, the spermidine and spermine content was higher in the Enterococcus -fermented sample (108.04 ± 6.69 and 22.93 ± 6.28 mg/kg, respectively). Therefore, these two bacterial species may contribute together to BA formation in Cheonggukjang but in slightly different manners. [Display omitted] • Prominent bacteria for biogenic amine (BA) formation in Cheonggukjang were unveiled. • Through metagenomics, Bacillus spp. were found to be tyramine and histamine producers. • Culturomic analysis revealed that Enterococcus spp. were the main tyramine producers. • During fermentation, Bacillus contributed more to tyramine content than Enterococcus. • Polyamines formed during fermentation was due to Enterococcus rather than Bacillus. [ABSTRACT FROM AUTHOR]

Hazardous levels of biogenic amines (BA) are frequently detected in soy sauce. However, the microorganisms and mechanisms responsible for BA formation in soy sauce are not well understood. In this study, we investigated the dynamic changes and metabolic pathways of BAs during soy sauce fermentation via metabolome and metagenomic analyses. Spermidine and putrescine were the main BAs detected during koji making, while putrescine, tyramine, phenylethylamine, and histamine were dominant during moromi fermentation. PCA analysis revealed that the soy sauce fermentation process could be divided into five representative stages based on the dynamics of BAs. Metagenomic analysis uncovered that a total of 15 genera were mainly involved in BAs formation, particularly, histamine was principally produced by Klebsiella , and Bacillus was the major tyramine-synthesizing bacteria. Correlation analysis showed that pH increase inhibited the spermidine production during koji making, whereas elevated NaCl concentration facilitated the phenylethylamine formation during moromi fermentation. Co-occurrence network analysis unveiled the associations between the BA-producing microorganisms and other genera. Overall, these results have improved our understanding of the mechanism of BA formation during soy sauce fermentation and guided the development of fermentation agents capable of degrading BA in industrial manufacture soy sauce production. • Dynamics of biogenic amines were classified into five stages during soy sauce fermentation. • Spermidine, putrescine, tyramine, phenylethylamine, and histamine were the dominant BAs during soy sauce fermentation. • Biogenic amine metabolic network in soy sauce was constructed. • Enzymes and genera in the formation of biogenic amines were annotated. • The key factors affecting biogenic amine formation were revealed. [ABSTRACT FROM AUTHOR]

Tyramine signal amplification (TSA) has made its mark in immunoassay due to its excellent signal amplification ability and short reaction time, but its application in nucleic acid detection is still very limited. Herein, an ultrasensitive microRNA (miRNA) biosensor by coupling hybridization-initiated exonuclease I (Exo I) protection and TSA strategy was established. Target miRNA is complementarily hybridized to the biotin-modified DNA probe to form a double strand, which protects the DNA probe from Exo I hydrolysis. Subsequently, horseradish peroxidase (HRP) is attached to the duplex via the biotin-streptavidin reaction and catalyzes the deposition of large amounts of biotin-tyramine in the presence of hydrogen peroxide (H 2 O 2), followed by the conjugation of signal molecule streptavidin-phycoerythrin (SA-PE), which generates an intense fluorescence signal upon laser excitation. This method gave broad linearity in the range of 0.1 fM - 10 pM, yielding a detection limit as low as 74 aM. An increase in sensitivity of 4 orders of magnitude was observed compared to the miRNA detection without TSA amplification. This biosensor was successfully applied to the determination of miR-21 in breast cancer cells and human serum. By further design of specific DNA probes and coupling with the Luminex xMAP technology, it could be easily extended to multiplex miRNA assay, which possesses great application potential in clinical diagnosis. [Display omitted] • Novel assay of miRNA coupled with Exo I and TSA. • Excellent miRNA detection performance with a detection limit at aM. • 3–4 orders of magnitude of improvement in sensitivity by TSA. • Successful application for miRNA detection at the cellular level and blood level. [ABSTRACT FROM AUTHOR]

Abstract Objectives Photocrosslinking systems of polymers have been widely studied using UV or visible light irradiation. However, the photodegradation behavior derived from light irradiation was rarely reported, comparing with the photocrosslinking. In this study, the tyramine-modified hyaluronic acid (HA/Tyr) hydrogel was prepared using riboflavin (RF) as a photoinitiator, and the degradation behavior of HA by the reactive oxygen species (ROS) generated in photochemical process was investigated. Materials and methods The HA/Tyr conjugate was synthesized by EDC/NHS chemistry to introduce phenol group. Degree of substitution (DS, %) of phenol group to HA molecule was about 25%. The structural change of HA/Tyr was measured by proton nuclear magnetic resonance (1H-NMR) and attenuated total reflectance infrared spectroscopy (ATR-FTIR), and the rheological properties of photocrosslinked HA/Tyr hydrogel were investigated by rheometer. Results The HA/Tyr solution with 25% substitution formed a stable hydrogel via visible light irradiation in the presence of RF photoinitiator. Rheological data of HA/Tyr solution showed that the storage modulus (G’) was increased with increasing HA concentration. Additionally, it was found that RF initiated by visible light irradiation induced the degradation of HA molecular chain, and consequently reduced the viscosity of HA/Tyr solutions. Conclusion The results indicate that RF-based photoinitiator system caused the degradation of HA molecule by ROS generated in photochemical process as well as the crosslinking of HA/Tyr.

Neurotransmission related signals are involved in the control of response to toxicants. We here focused on the tyramine and the glutamate related signals to determine their roles in regulating nanoplastic toxicity in Caenorhabditis elegans. In the range of μg/L, exposure to nanopolystyrene (100 nm) increased the expression of tdc-1 encoding a tyrosine decarboxylase required for synthesis of tyramine, and decreased the expression of eat-4 encoding a glutamate transporter. Both TDC-1 and EAT-4 could act in the neurons to regulate the nanopolystyrene toxicity. Meanwhile, neuronal RNAi knockdown of tdc-1 induced a susceptibility to nanopolystyrene toxicity, and neuronal RNAi knockdown of eat-4 induced a resistance to nanopolystyrene toxicity. In the neurons, TYRA-2 functioned as the corresponding receptor of tyramine and acted upstream of MPK-1 signaling to regulate the nanopolystyrene toxicity. Moreover, during the control of nanopolystyrene toxicity, GLR-4 and GLR-8 were identified as the corresponding glutamate receptors, and acted upstream of JNK-1 signaling and DBL-1 signaling, respectively. Our results demonstrated the crucial roles of tyramine and glutamate related signals in regulating the toxicity of nanoplastics in organisms.

Diagnosis of pheochromocytomas and paragangliomas in patients receiving hemodialysis is troublesome. The aim of the study was to establish optimal conditions for blood sampling for mass spectrometric measurements of normetanephrine, metanephrine and 3-methoxytyramine in patients on hemodialysis and specific reference intervals for plasma metanephrines under the most optimal sampling conditions. Blood was sampled before and near the end of dialysis, including different sampling sites in 170 patients on hemodialysis. Plasma normetanephrine concentrations were lower (P < 0.0001) and metanephrine concentrations higher (P < 0.0001) in shunt than in venous blood, with no differences for 3-methoxytyramine. Normetanephrine, metanephrine and 3-methoxytyramine concentrations in shunt and venous blood were lower (P < 0.0001) near the end than before hemodialysis. Upper cut-offs for normetanephrine were 34% lower when the blood was drawn from the shunt and near the end of hemodialysis compared to blood drawn before hemodialysis. This study establishes optimal sampling conditions using blood from the dialysis shunt near the end of hemodialysis with optimal reference intervals for plasma metanephrines for the diagnosis of pheochromocytomas/paragangliomas among patients on hemodialysis. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Monoamine oxidase inhibitors (MAOIs) exert therapeutic actions by elevating extracellular levels of monoamines in the brain. Irreversible MAOIs cause serious hypertensive crises owing to peripheral accumulation of tyramine, but the role of tyramine in the central effects of MAOIs remains elusive, an issue addressed herein. To achieve robust inhibition of MAOA/B, the clinically used antidepressant tranylcypromine (TCP) was employed. Behavioral, histological, mass spectrometry imaging, and biosensor-mediated measures of glutamate were conducted with MAOIs in wild-type and TAAR1-knockout (KO) mice. Both antidepressant and locomotion responses to TCP were enhanced in TAAR1-KO mice. A recently developed fluoromethylpyridinium-based mass spectrometry imaging method revealed robust accumulation of striatal tyramine on TCP administration. Furthermore, tyramine accumulation was higher in TAAR1-KO versus wild-type mice, suggesting a negative feedback mechanism for TAAR1 in sensing tyramine levels. Combined histoenzymological and immunohistological studies revealed hitherto unknown TAAR1 localization in brain areas projecting to the substantia nigra/ventral tegmental area. Using an enzyme-based biosensor technology, we found that both TCP and tyramine reduced glutamate release in the substantia nigra in wild-type but not in TAAR1-KO mice. Moreover, glutamate measures in freely moving animals treated with TCP demonstrated that TAAR1 prevents glutamate accumulation in the substantia nigra during hyperlocomotive states. These observations suggest that tyramine, in interaction with glutamate, is involved in centrally mediated behavioral, transcriptional, and neurochemical effects of MAOIs. [ABSTRACT FROM AUTHOR]

Identifying mechanisms underlying alcohol‐related behaviors could provide important insights regarding the etiology of alcohol use disorder. To date, most genetic studies on alcohol‐related behavior in model organisms have focused on neurons, leaving the causal roles of glial mechanisms less comprehensively investigated. Here, we report our studies on the role of Tyrosine decarboxylase 2 (Tdc2), which converts tyrosine to the catecholamine tyramine, in glial cells in Drosophila alcohol sedation. Using genetic approaches that drove transgene expression constitutively in all glia, constitutively in astrocytes and conditionally in glia during adulthood, we found that knockdown and overexpression of Tdc2, respectively, increased and decreased the sensitivity to alcohol sedation in flies. Manipulation of the genes tyramine β‐hydroxylase and tyrosine hydroxylase, which respectively synthesize octopamine and dopamine from tyramine and tyrosine, had no discernable effect on alcohol sedation, suggesting that Tdc2 affects alcohol sedation by regulating tyramine production. We also found that knockdown of the vesicular monoamine transporter (VMAT) and disruption of the SNARE complex in all glia or selectively in astrocytes increased sensitivity to alcohol sedation and that both VMAT and the SNARE complex functioned downstream of Tdc2. Our studies support a model in which the synthesis of tyramine and vesicle‐mediated release of tyramine from adult astrocytes regulates alcohol sedation in Drosophila. Considering that tyramine is functionally orthologous to norepinephrine in mammals, our results raise the possibility that gliotransmitter synthesis release could be a conserved mechanism influencing behavioral responses to alcohol as well as alcohol use disorder. [ABSTRACT FROM AUTHOR]

The physicochemical properties, color characteristics, and biogenic amine (BA) concentrations of Konya Green cheese during ripening process with mold were investigated. Four productions were made in different periods, and the samples were analyzed at the end of the cold storage period (0) and on days 1, 3, 7, 15, 21, 24, and 30 of mold ripening. It was found that dry matter, acidity, and salt values tend to increase, whereas pH and aw values tend to decrease during the mold ripening period in all production groups. Total BA content increased significantly from 70.91 to 136.95 mg/kg during the ripening period (p <.01). Principal components explained 92.5% of the total variation among the four production group cheese. Based on the Hierarchical clustering analysis, three clusters were obtained: 1st (0, 3, 15), 2nd (1, 24, 30), and 3rd (7, 21). Tyramine, cadaverine, putrescine, and histamine were observed in 2nd cluster as per the PCA. Novelty impact statement: The biogenic amine formation and dominancy of the principal biogenic amins through ripening period of Konya Green cheese were determined using RP‐HPLC. The predominant biogenic amines determined at the end of the ripening time were tyramine, cadaverine, and putrescine which represent around 81% of the total BA present. To the best of our knowledge, this is the first study for determinig the biogenic amin production of Konya Green cheese. [ABSTRACT FROM AUTHOR]

Copyright of China Brewing is the property of China Brewing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Biogenic amines (BAs) produced by the action of bacterial amino acid decarboxylases in fermented foods cause various health problems in human. Despite the importance, detailed characterizations of the BA-producing decarboxylases are relatively less progressed than the studies on BA-producing bacteria, due to the time-consuming chromatography-based assay method. In this study, a simple and general colorimetric assay for aromatic amino acid decarboxylases coupled with an amine oxidase from Arthrobacter aurescens (AMAO) and horseradish peroxidase was developed using a tyrosine decarboxylase from Enterococcus faecium DSM20477 (EfmTDC) as a model enzyme. The activity profiles over pH and temperature and the kinetic analysis for EfmTDC revealed that the results by the colorimetric assay are compatible with those by the chromatographic assay. In addition, due to the broad substrate specificity of AMAO for histamine and 2-phenylethylamine, the colorimetric assay would be applicable to the characterization of other aromatic amino acid decarboxylases including histidine decarboxylases. [ABSTRACT FROM AUTHOR]

Background: Bariatric surgery, used to achieve effective weight loss in individuals with severe obesity, modifies the gut microbiota and systemic metabolism in both humans and animal models. The aim of the current study was to understand better the metabolic functions of the altered gut microbiome by conducting deep phenotyping of bariatric surgery patients and bacterial culturing to investigate causality of the metabolic observations. Methods: Three bariatric cohorts (n = 84, n = 14 and n = 9) with patients who had undergone Roux-en-Y gastric bypass (RYGB), sleeve gastrectomy (SG) or laparoscopic gastric banding (LGB), respectively, were enrolled. Metabolic and 16S rRNA bacterial profiles were compared between pre- and post-surgery. Faeces from RYGB patients and bacterial isolates were cultured to experimentally associate the observed metabolic changes in biofluids with the altered gut microbiome. Results: Compared to SG and LGB, RYGB induced the greatest weight loss and most profound metabolic and bacterial changes. RYGB patients showed increased aromatic amino acids-based host-bacterial co-metabolism, resulting in increased urinary excretion of 4-hydroxyphenylacetate, phenylacetylglutamine, 4-cresyl sulphate and indoxyl sulphate, and increased faecal excretion of tyramine and phenylacetate. Bacterial degradation of choline was increased as evidenced by altered urinary trimethylamine-N-oxide and dimethylamine excretion and faecal concentrations of dimethylamine. RYGB patients' bacteria had a greater capacity to produce tyramine from tyrosine, phenylalanine to phenylacetate and tryptophan to indole and tryptamine, compared to the microbiota from non-surgery, normal weight individuals. 3-Hydroxydicarboxylic acid metabolism and urinary excretion of primary bile acids, serum BCAAs and dimethyl sulfone were also perturbed following bariatric surgery. Conclusion: Altered bacterial composition and metabolism contribute to metabolic observations in biofluids of patients following RYGB surgery. The impact of these changes on the functional clinical outcomes requires further investigation. 1v6mePHgvKoyyAii3YMczB Video abstract [ABSTRACT FROM AUTHOR]

The effect of ε‐polylysine hydrochloride (ε‐PL) and thymol (TY) in the changes of biogenic amines (BAs) and the quality properties of Illex argentinus was evaluated by measuring the content of BAs, total viable count (TVC), pH, sensory score, and odor change. The experiment was divided into four groups, the control, ε‐PL, TY, and the compound (ε‐PL–TY) group. The results showed BAs‐producing bacteria contained Enterobacteriaceae bacterium, Citrobacter braakii, Klebsiella pneumoniae, Obesumbacterium proteus, Hafnia alvei, Hafnia paralvei, and Hafnia alvei sensu. ε‐PL, TY, and ε‐PL–TY effectively inhibited the increase of BAs content, TBA, pH, and maintained the fresh flavor and sensory properties. ε‐PL–TY was the best to reduce the content of phenethylamine, putrescine, cadaverine, and tyramine by 45.11%, 79.08%, 72.92%, and 63.53% compared with the control at the end of storage. ε‐PL–TY was a promising BAs inhibitor that could protect the edible value and safety of aquatic products. Practical applications: Illex argentinus is susceptible to corruption, and then microorganism in Illex argentinus will produce several biogenic amines, while the combined preservative is the most convenient way to protect its quality after postmortem. Although ε‐polylysine hydrochloride has a better antibacterial activity as a preservative, the single preservative cannot exert a better effect. Thymol is a natural plant ingredient with great antioxidant properties and antibacterial activities, which had an inhibitory synergy with ε‐PL in this study. ε‐polylysine hydrochloride– thymol could be a promising preservative to control the biochemistry activities and protect the edible value of squid. [ABSTRACT FROM AUTHOR]

Objective: To study the protective effects of N-trans-feruloyltyramine (NTF) on scopolamine-induced cholinergic dysfunction, apoptosis, and inflammation in rat brains. Materials and Methods: Treatments were administered intraperitoneally (i.p.). Wistar rats (8-week-old) were allocated into 4 groups (n = 3) as follows: scopolamine-only, NTF-only, NTF + scopolamine and control. Spatial cognition was evaluated by Morris water maze. ROS assay and Western blot analyses were conducted in 3 brain regions: the frontal cortex, hippocampus, and temporal cortex. Results: NTF treatment inhibited scopolamine-induced memory impairment and significantly attenuated scopolamineinduced changes in the three brain regions. Investigated scopolamine-associated changes were as follows: increases in ROS production and BACE1 level, decrease in ChAT level, increases in inflammatory and apoptotic markers, and activation of signaling pathway kinases related to inflammation and apoptosis. Conclusion: With its in vivo antioxidant, cholinergic-promoting, anti-apoptosis, and anti-inflammatory biological activities, NTF is a promising candidate to be further investigated as a potential treatment for Alzheimer's-associated neurodegeneration. [ABSTRACT FROM AUTHOR]

Tyrosine decarboxylase (TyDC), a pyridoxal-5′-phosphate (PLP)-dependent aromatic amino acid decarboxylase, catalyzes the decarboxylation of l-tyrosine (Tyr) to generate the important biogenic tyramine. This amine was reported to be a biosynthetic precursor of the Amaryllidaceae alkaloids, a group of pharmaceutically important natural products. Herein, we cloned two TyDC-encoding genes from Lycoris radiata, a galanthamine (GAL, a characteristic Amaryllidaceae alkaloid)-producing and medicinally and ornamentally important perennial herbaceous plant. Heterologous expression of LrTyDCs in Escherichia coli and the following purification gave recombinant LrTyDCs to homogeneity for enzymatic reactions. Tyramine was detected and validated by HPLC–DAD and HRESIMS analyses of the LrTyDC-catalyzed reaction mixture, which revealed the catalytic decarboxylation activity of LrTyDCs. The transcriptional LrTyDCs were detected in all tissues of L. radiata by quantitative real-time PCR analyses. The present works demonstrated that TyDC-catalyzed decarboxylation reaction is a key step to generate the non-catechol biosynthetic precursor of the Amaryllidaceae alkaloids. [ABSTRACT FROM AUTHOR]

Bacterial vaginosis (BV) is the most common vaginal disorder of reproductive-aged women, yet its etiology remains enigmatic. One clinical symptom of BV, malodor, is linked to the microbial production of biogenic amines (BA). Using targeted liquid chromatography mass spectrometry, we analyzed 149 longitudinally collected vaginal samples to determine the in vivo concentrations of the most common BAs and then assessed their relationship to BV and effect upon the growth kinetics of axenically cultured vaginal Lactobacillus species. Increases in cadaverine, putrescine, and tyramine were associated with greater odds of women transitioning from L. crispatus-dominated vaginal microbiota to microbiota that have a paucity of Lactobacillus spp. and from Nugent scores of 0 to 3 to Nugent scores of 7 to 10, consistent with BV. Exposure to putrescine lengthened the lag time and/or slowed the growth of all vaginal Lactobacillus spp. except L. jensenii 62G. L. iners AB107's lag time was lengthened by cadaverine but reduced in the presence of spermidine and spermine. The growth rate of L. crispatus VPI 3199 was slowed by cadaverine and tyramine, and strain-specific responses to spermine and spermidine were observed. BAs were associated with reduced production of D- and L-lactic acid by vaginal Lactobacillus spp., and this effect was independent of their effect upon Lactobacillus species growth. The exceptions were higher levels of D- and L-lactic acid by two strains of L. crispatus when grown in the presence of spermine. Results of this study provide evidence of a direct impact of common biogenic amines on vaginal Lactobacillus spp. IMPORTANCE Lactobacillus spp. are credited with providing the primary defense against gynecological conditions, including BV, most notably through the acidification of the vaginal microenvironment, which results from their production of lactic acid. The microbial production of BAs has been hypothesized to play a mechanistic role in diminishing Lactobacillus species-mediated protection, enabling the colonization and outgrowth of diverse anaerobic bacterial species associated with BV. Here, we demonstrate that in vivo increases in the most commonly observed BAs are associated with a loss of Lactobacillus spp. and the development of BV, measured by Nugent score. Further, we show that BAs formed by amino acid decarboxylase enzymes negatively affect the growth of type strains of the most common vaginal Lactobacillus spp. and separately alter their production of lactic acid. These results suggest that BAs destabilize vaginal Lactobacillus spp. and play an important and direct role in diminishing their protection of the vaginal microenvironment. [ABSTRACT FROM AUTHOR]

Ribonucleoprotein (RNP) granules are dynamic condensates enriched in regulatory RNA binding proteins (RBPs) and RNAs under tight spatiotemporal control. Extensive recent work has investigated the molecular principles underlying RNP granule assembly, unraveling that they form through the self-association of RNP components into dynamic networks of interactions. How endogenous RNP granules respond to external stimuli to regulate RNA fate is still largely unknown. Here, we demonstrate through high-resolution imaging of intact Drosophila brains that Tyramine induces a reversible remodeling of somatic RNP granules characterized by the decondensation of granule-enriched RBPs (e.g. Imp/ZBP1/IGF2BP) and helicases (e.g. Me31B/DDX-6/Rck). Furthermore, our functional analysis reveals that Tyramine signals both through its receptor TyrR and through the calcium-activated kinase CamkII to trigger RNP component decondensation. Finally, we uncover that RNP granule remodeling is accompanied by the rapid and specific translational activation of associated mRNAs. Thus, this work sheds new light on the mechanisms controlling cue-induced rearrangement of physiological RNP condensates. [ABSTRACT FROM AUTHOR]

The constant development and improvement of microelectromechanical systems (MEMS) have been given a great opportunity to develop new reliable microsystems devices for biomedical research. This article presents a locally addressable 2-D arrayed indium–tin oxide microelectrode platform with integrated thin-film transistors (TFTs) for biological and chemical sensing. Microelectrode arrays (MEAs) using TFT have the advantage of being transparent with a high density of microelectrodes on a large surface. In vitro 2-D electrical measurements on 28 parallel-connected lines selected from a 22 500 MEA were successfully performed with heart cells for the first time. Observation of cell contraction was performed simultaneously with an inverted microscope. Voltammetry and amperometry measurements were also demonstrated using the transparent microelectrodes as working electrodes and an integrated Ag/AgCl reference electrode. Due to its unique features, we believe that the TFT platform can provide more understanding of the key communication between heart cells, and large-scale cardiovascular and nervous systems. As a result, the platform offers unique access to versatile lab-on-a-chip devices that integrate many measurement techniques on one chip for the study of cell cultures, tissues, and organoids. [ABSTRACT FROM AUTHOR]

Regulation of pollen and nectar foraging in honeybees is linked to differences in the sensitivity to the reward. Octopamine (OA) participates in the processing of reward‐related information in the bee brain, being a candidate to mediate and modulate the division of labour among pollen and nectar foragers. Here we tested the hypothesis that OA affects the resource preferences of foragers. We first investigated whether oral administration of OA is involved in the transition from nectar to pollen foraging. We quantified the percentage of OA‐treated bees that switched from a sucrose solution to a pollen feeder when the sugar concentration was decreased experimentally. We also evaluated if feeding the colonies sucrose solution containing OA increases the rate of bees collecting pollen. Finally, we quantified OA and tyramine (TYR) receptor genes expression of pollen and nectar foragers in different parts of the brain, as a putative mechanism that affects the decision‐making process regarding the resource type collected. Adding OA in the food modified the probability that foragers switch from nectar to pollen collection. The proportion of pollen foragers also increased after feeding colonies with OA‐containing food. Furthermore, the expression level of the AmoctαR1 was upregulated in foragers arriving at pollen sources compared with those arriving at sugar‐water feeders. Using age‐matched pollen and nectar foragers that returned to the hive, we detected an upregulated expression of a TYR receptor gene in the suboesophageal ganglia. These findings support our prediction that OA signalling affects the decision in honeybee foragers to collect pollen or nectar. [ABSTRACT FROM AUTHOR]

This work reports a voltammetric sensor for the individual and simultaneous determination of two important biogenic amines serotonin (ST) and tyramine (TYM) based on L-cysteine grafted glassy carbon electrode (p(L-cys)/GCE). Square wave voltammetric results reveal that the overpotential for the electro oxidation of these compounds were decreased and the peak current increased significantly at the modified electrode compared to bare GCE. The sensor displayed well defined peaks with sufficient peak separation for the simultaneous determination of these compounds when phosphate buffer of pH 7 was used as the supporting medium. All the sensor parameters were optimized and under these conditions, determinations have been achieved in wide linear ranges with nanomolar detection limits both individually and simultaneously. The proposed sensor has been used for practical application in synthetic blood serum samples. [ABSTRACT FROM AUTHOR]

In this study, biogenic amines levels of Van herby cheese (Van Otlu peynir) matured in dry-salted/filling (basma) and brine (salamura)-salted techniques were investigated. For this purpose, a total of 100 herby cheese samples matured by dry-salted and brine-salted techniques (50 dry-salted and 50 brine-salted) were purchased from the grocery stores in Van province, and chemical characteristics and biogenic amines contents of the samples were determined. The mean chemical composition for Van herby cheese matured by dry-salted method and brine-salted methods were, respectively, as follows: pH value 4.62 and 5.16, acidity 1.50% and 1.08%, salt content 7.85% and 7.15%, dry matter content 59.07% and 49.22%, fat 27.00% and 23.43%, protein content 23.39% and 17.17% and protein hydrolysis of 100.92 mM and 79.57 mM, indicating that dry-salted Van herby cheese had significantly lower pH values and significantly greater acidity and protein, dry matter, and fat content than brine-salted Van herby cheese (P < 0.05). In addition, only the tyramine levels were significantly greater in the dry-salted group than the brine-salted group approximately twice high (P < 0.001). In terms of the other biogenic amines, no significant difference was found between two groups (P > 0.05). In conclusion, none of the biogenic amines levels measured in Van herby cheese produced by both techniques were above the levels considered to be dangerous for human health. More detailed research is needed to better elucidate the importance of present findings in terms of human health. [ABSTRACT FROM AUTHOR]

In this study, non-enzymatic and enzymatic tyramine sensors were prepared by using P[5]A as a surface modification material. P[5]A, which belongs to the group of ionic liquids, enables the development of a biocompatible and stable electroactive electrode surface. In the modification process, P[5]A dispersed in gelatin solution was dropped on a glassy carbon electrode (GCE). In the preparation of enzymatic sensor, tyrosinase (TYR) was immobilized by used glutaraldehyde as a cross-linker on P[5]A modified GCE surface. Surface morphology and electrochemical behavior of P[5]A modified GCE was investigated by scanning electron microscope (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Experimental conditions such as pH, working potential and P[5]A amount were optimized as GCE/Gel/P[5]A and GCE/Gel/P[5]A/TYR. Under optimum experimental conditions, linear working ranges of GCE/Gel/P[5]A and GCE/Gel/P[5]A/TYR was $8.0\times 10^{-8} - 1.5\times 10^{-6}$ M with LOD of $4.0\times 10^{-8}$ M and $1.6\times 10^{-6} - 4.2\times 10^{-5}\text{M}$ with LOD of $5.0\times 10^{-7}$ M, respectively. These sensors showed a lower detection limit, high selectivity and good repeatability for tyramine. Analytical applicability of non-enzymatic and enzymatic sensor was examined by tyramine analysis and recovery studies in the sauerkraut sample. [ABSTRACT FROM AUTHOR]

Controlling the content of biogenic amines (BAs) is critical to guarantee the safety of fermented aquatic products. The degradation characteristics and application potential of amine-negative starter cultures (Virgibacillus halodenitrificans CGMCC 1.18601: G25, Virgibacillus pantothenticus CGMCC 1.18602: G38) screened from grasshopper sub shrimp paste (Gssp) were studied. The enzymes of the two strains G25 and G38 that degrade BAs were amine oxidases (AOs) located on their respective cell membranes. The conditions that promoted the AO activity of Virgibacillus spp. were NaCl concentrations 5–10%, temperature 37 °C, pH 7.0 and ethanol concentrations 0–2%. Safety assessments (antibiotic susceptibility, biofilm activity and hemolytic activity) indicated that Virgibacillus spp. do not present a risk to human health, and this isolate can be confidently recommended as safe starter cultures for the food industry. Then, the two strains were cultured separately as starters and applied to the Gssp to analyze their influence on the flavor and quality of the product. As far as the bad flavors in Gssp such as sulfur-organic and sulf-chlor were concerned, the response values in the starter groups by G25 and G38 were significantly reduced by 39% and 65%, respectively. For the ability of strains to degrade BAs in Gssp, G25 degraded 11.1% of histamine, 11.3% of tyramine, 15.5% of putrescine and 4.1% of cadaverine; G38 significantly degraded 10.1% of histamine, 21.8% of tyramine, 18.1% of putrescine and 5.0% of cadaverine. These results indicated that the selected species could be used as starter cultures for the control of BA accumulation and degradation in Gssp. [ABSTRACT FROM AUTHOR]

This study addresses the application of native, multiple strain starter cultures for standardization of game meat sausages production. The designed starter cultures consisting of two indigenous Lactobacillus sakei and one Leuconostoc mesenteroides strains. These strains were used in both, the encapsulated and non-encapsulated form, in the game meat dough, individually or in combination, with eight treatments in total. Microbiological and physicochemical characteristics of the sausages were monitored throughout the manufacturing process, while sensory properties, biogenic amine content, and volatile compounds were evaluated in the final products. As revealed by rep-PCR, native starter cultures, encapsulated or non-encapsulated, had survived the whole sausage production process; however, to varying degrees. The application of indigenous decarboxylase negative Lb. sakei strains significantly (P < 0.05) reduced tyramine content, rapidly decreased pH and promoted the number reduction of Enterobacteriaceae and elimination of E. coli, L. monocytogenes and coliforms in ready-to-eat products. A total of 84 volatile compounds were identified by SPME–GC–MS in the eight treatment batches of game meat sausages, with only minor differences between the treatments. No significant differences in sensory traits (P > 0.05) between tested treatments were found, although treatment with the Lb. sakei strains received the highest scores for the sensory traits including cross-section, odour, hardness, aroma, and overall acceptability. Combination of multi-strain Lb. sakei starter cultures resulted in growth prevention of undesirable microbiota, reduction of tyramine content and increased the acceptability parameters of full-ripened sausages, which make them good candidates for industrial as well as artisanal application. [ABSTRACT FROM AUTHOR]

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The goal of this study was to examine vascular control after sympathetic stimulation by tyramine infusion in hypertensive rats submitted to swimming training. To this end, male rats were assigned to the following groups: sedentary (SN) and trained normotensive (TN), sedentary (SH) and trained hypertensive (TH). Arterial pressure (AP), heart rate (HR), HR variability (HRV), AP variability (APV), and cardiac autonomic function were recorded. Following, infusion of tyramine was administrated. The TN and TH showed a lower resting HR compared with their respective sedentary groups (p <.05). Pressure levels were less in TH than SH (p <.05). The TH showed a higher HRV together with a lower APV in comparison to SH (p <.05). The sympathetic modulation of HRV and APV was lower in TH than in SH (p <.05). Both trained groups presented an increased parasympathetic modulation of HRV compared with their respective sedentary groups (p <.05). The TN and TH groups had a higher vagal effect in comparison with their respective sedentary groups (p <.001). The sympathetic effect was lower in TH than in SH (p <.001). Pressor and HR responses to tyramine in different doses were attenuated in TH (p <.001). Further analysis showed a significant association between infusion of tyramine and normalized LF component of HRV (r = 0.84, p <.001), systolic APV (r = 0.58, p <.001) and diastolic APV (r = 0.49, p <.001). In conclusion, exercise training provokes less pressor response variation by tyramine infusion in hypertensive animals suggesting sympathetic nerve endings adjustments and decrease of the vasoconstrictor effect attenuates injury caused by hypertension improving cardiovascular autonomic dysfunction, which can be associated with sympathetic attenuation. [ABSTRACT FROM AUTHOR]

Tyramine (TRM) is a biogenic catecholamine neurotransmitter, which can trigger migraines and hypertension. TRM accumulated in foods is reduced and detected using additive cyclodextrins (CDs) while their association characteristics remain unclear. Here, single-crystal X-ray diffraction and density functional theory (DFT) calculation have been performed, demonstrating the elusive pseudopolymorphs in β-CD inclusion complexes with TRM base/HCl, β-CD·0.5TRM·7.6H 2 O ( 1 ) and β-CD·TRM HCl·4H 2 O ( 2 ) and the rare α-CD·0.5(TRM HCl)·10H 2 O ( 3 ) exclusion complex. Both 1 and 2 share the common inclusion mode with similar TRM structures in the round and elliptical β-CD cavities, belong to the monoclinic space group P 2 1 , and have similar herringbone packing structures. Furthermore, 3 differs from 2 , as the smaller twofold symmetry-related, round α-CD prefers an exclusion complex with the twofold disordered TRM-H + sites. In the orthorhombic P 2 1 2 1 2 lattice, α-CDs are packed in a channel-type structure, where the column-like cavity is occupied by disordered water sites. DFT results indicate that β-CD remains elliptical to suitably accommodate TRM, yielding an energetically favorable inclusion complex, which is significantly contributed by the β-CD deformation, and the inclusion complex of α-CD with the TRM aminoethyl side chain is also energetically favorable compared to the exclusion mode. This study suggests the CD implications for food safety and drug/bioactive formulation and delivery.

This study investigated the safety and functionality of traditional African sourdough flatbread (kisra), based on the content of biogenic amines (BAs) and antioxidant compounds and their improvement using lactic acid bacteria (LAB) species. The primary BAs detected in naturally fermented kisra were tyramine, histamine, putrescine, and cadaverine, with putrescine being the most abundant after baking. In vitro BA production of microorganisms isolated from kisra sourdough revealed that the Enterococcus genus contributed to tyramine accumulation, whereas presumptive yeasts may contribute to putrescine and cadaverine accumulation. The use of LAB species, including Lactiplantibacillus plantarum , Limosilactobacillus fermentum , Levilactobacillus brevis , and Weissella cibaria , significantly reduced putrescine content to less than about 23% of that of naturally fermented kisra, and eliminated tyramine, histamine, and cadaverine formation. Meanwhile, DPPH scavenging activity, total polyphenolic content, and tannin content in naturally fermented kisra were 85.16%, 1386.50 µg/g, and 33.16 µg/g, respectively. The use of LAB species did not affect the DPPH scavenging activity or tannin content but significantly increased the total phenolic content by up to 20% compared to naturally fermented kisra. Therefore, fermentation with LAB starter cultures might be a promising approach to improve the safety related to BAs as well as the functionality of kisra bread.

Cheese is a food in which toxic concentrations of biogenic amines (BA) may be reached, mainly as a consequence of the decarboxylation of determined amino acids by certain lactic acid bacteria (LAB). To maintain the food safety of cheese, environmentally friendly strategies are needed that specifically prevent the growth of BA-producing LAB and the accumulation of BA. The bacteriocins produced by LAB are natural compounds with great potential as food biopreservatives. This work examines the antimicrobial potential of 7 bacteriocin-containing, cell-free supernatants (CFS: coagulin A-CFS, enterocin A-CFS, enterocin P-CFS, lacticin 481-CFS, nisin A-CFS, nisin Z-CFS and plantaricin A-CFS) produced by LAB against 48 strains of the LAB species largely responsible for the accumulation of the most important BA in cheese, that is, histamine, tyramine, and putrescine. Susceptibility to the different CFS was strain-dependent. The histamine-producing species with the broadest sensitivity spectrum were Lentilactobacillus parabuchneri (the species mainly responsible for the accumulation of histamine in cheese) and Pediococcus parvulus. The tyramine-producing species with the broadest sensitivity spectrum was Enterococcus faecium, and Enterococcus faecalis and Enterococcus hirae were among the most sensitive putrescine producers. Nisin A-CFS was active against 31 of the 48 BA-producing strains (the broadest antimicrobial spectrum recorded). Moreover, commercial nisin A prevented biofilm formation by 67% of the BA-producing, biofilm-forming LAB strains. These findings underscore the potential of bacteriocins in the control of BA-producing LAB and support the use of nisin A as a food-grade biopreservative for keeping BA-producing LAB in check and reducing BA accumulation in cheese., (The Authors. Published by Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

A fluorescence probe based on molecularly imprinted polymers on red emissive biomass-derived carbon dots (r-BCDs@MIPs) was developed to detect tyramine in fermented meat products. The red emissive biomass-derived carbon dots (r-BCDs) were synthesized by the one-step solvothermal method using discarded passion fruit shells as raw materials. The fluorescence emission peak of r-BCDs was at 670 nm, and the relative quantum yield (QY) was about 2.44%. Molecularly imprinted sensing materials were prepared with r-BCDs as fluorescent centers for the detection of trace tyramine, which showed a good linear response in the concentration range of tyramine from 1 to 40 µg L -1 . The linear correlation coefficient was 0.9837, and the limit of detection was 0.77 µg L -1 . The method was successfully applied to the determination of tyramine in fermented meat products, and the recovery was 87.17-106.02%. The reliability of the results was verified through high-performance liquid chromatography (HPLC). Furthermore, we combined the r-BCDs@MIPs with smartphone-assisted signal readout to achieve real-time detection of tyramine in real samples. Considering its simplicity and convenience, the method could be used as a rapid and low-cost promising platform with broad application prospects for on-site detection of trace tyramine with smartphone-assisted signal readout., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

This study analyzed biogenic amine (BA) content in three varieties (types) of kimchi ( Baechu kimchi, Baek kimchi, and Yeolmu kimchi), identified the causative bacteria, and evaluated the gene expression associated with the BA formation during kimchi fermentation at 4 °C. Histamine content exceeding the toxicity limit was detected in a single Baechu kimchi product. Tyramine content in most Baechu kimchi products was approximately half of the toxicity limit. Other varieties had relatively lower BA content. Most BA producers isolated from all kimchi varieties were identified as Levilactobacillus brevis , which prominently produced tyramine. To clarify the role of L. brevis in tyramine formation in Baechu kimchi, fermentation experiments were performed using L . brevis BC1M20. The results showed that tyramine content and tyrosine decarboxylase gene ( tdc ) expression were higher in the inoculated kimchi than in the control. In addition, in the inoculated kimchi, the content decreased while the expression level was almost constant., Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-024-01627-8., Competing Interests: Conflict of interestThe authors declare no conflicts of interest., (© The Korean Society of Food Science and Technology 2024. Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.)

Inflammatory bowel disease (IBD) is characterized by dysbiosis of the gut microbiota and dysfunction of intestinal stem cells (ISCs). However, the direct interactions between IBD microbial factors and ISCs are undescribed. Here, we identify α 2A -adrenergic receptor (ADRA2A) as a highly expressed GPCR in ISCs. Through PRESTO-Tango screening, we demonstrate that tyramine, primarily produced by Enterococcus via tyrosine decarboxylase (tyrDC), serves as a microbial ligand for ADRA2A. Using an engineered tyrDC-deficient Enterococcus faecalis strain and intestinal epithelial cell-specific Adra2a knockout mice, we show that Enterococcus-derived tyramine suppresses ISC proliferation, thereby impairing epithelial regeneration and exacerbating DSS-induced colitis through ADRA2A. Importantly, blocking the axis with an ADRA2A antagonist, yohimbine, disrupts tyramine-mediated suppression on ISCs and alleviates colitis. Our findings highlight a microbial ligand-GPCR pair in ISCs, revealing a causal link between microbial regulation of ISCs and colitis exacerbation and yielding a targeted therapeutic approach to restore ISC function in colitis., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Tyramine, a trace monoamine produced from tyrosine by decarboxylation and found naturally in foods, plants, and animals, is a suspected virulence factor of Melissococcus plutonius that causes European foulbrood in honey bee brood. In the present study, we developed a method for quantitative analysis of tyramine in culture medium and honey bee larvae with a limit of quantitation of 3 ng/mL and a recovery rate of >97% using Liquid Chromatography-Mass Spectrometry/Mass Spectrometry and deuterium-labeled tyramine, demonstrating for the first time that a highly virulent M. plutonius strain actually produces tyramine in infected larvae. This method will be an indispensable tool to elucidate the role of tyramine in European foulbrood pathogenesis in combination with exposure bioassays using artificially reared bee larvae.

Salmonella has evolved various metabolic pathways to scavenge energy from the metabolic byproducts of the host gut microbiota, however, the precise metabolic byproducts and pathways utilized by Salmonella remain elusive. Previously we reported that Salmonella can proliferate by deriving energy from two metabolites that naturally occur in the host as gut microbial metabolic byproducts, namely, tyramine (TYR, an aromatic amine) and d-glucuronic acid (DGA, a hexuronic acid). Salmonella Pathogenicity Island 13 (SPI-13) plays a critical role in the ability of Salmonella to derive energy from TYR and DGA, however the catabolic pathways of these two micronutrients in Salmonella are poorly defined. The objective of this study was to identify the specific genetic components and construct the regulatory circuits for the TYR and DGA catabolic pathways in Salmonella. To accomplish this, we employed TYR and DGA-induced global transcriptional profiling and gene functional network analysis approaches. We report that TYR induced differential expression of 319 genes (172 up-regulated and 157 down-regulated) when Salmonella was grown in the presence of TYR as a sole energy source. These included the genes originally predicted to be involved in the classical TYR catabolic pathway. TYR also induced expression of majority of genes involved in the acetaldehyde degradation pathway and aided identification of a few new genes that are likely involved in alternative pathway for TYR catabolism. In contrast, DGA induced differential expression of 71 genes (58 up-regulated and 13 down-regulated) when Salmonella was grown in the presence of DGA as a sole energy source. These included the genes originally predicted to be involved in the classical pathway and a few new genes likely involved in the alternative pathway for DGA catabolism. Interestingly, DGA also induced expression of SPI-2 T3SS, suggesting that DGA may also influence nutritional virulence of Salmonella. In summary, this is the first report describing the global transcriptional profiling of TYR and DGA catabolic pathways of Salmonella. This study will contribute to the better understanding of the role of TYR and DGA in metabolic adaptation and virulence of Salmonella.

Innate behaviours are flexible: they change rapidly in response to transient environmental conditions, and are modified slowly by changes in the genome. A classical flexible behaviour is the exploration-exploitation decision, which describes the time at which foraging animals choose to abandon a depleting food supply. We have used quantitative genetic analysis to examine the decision to leave a food patch in Caenorhabditis elegans. Here we show that patch-leaving is a multigenic trait regulated in part by naturally occurring non-coding polymorphisms in tyra-3 (tyramine receptor 3), which encodes a G-protein-coupled catecholamine receptor related to vertebrate adrenergic receptors. tyra-3 acts in sensory neurons that detect environmental cues, suggesting that the internal catecholamines detected by tyra-3 regulate responses to external conditions. These results indicate that genetic variation and environmental cues converge on common circuits to regulate behaviour, and suggest that catecholamines have an ancient role in regulating behavioural decisions.

Biogenic amines (BAs) can be found in a wide range of meat and meat products, where they are important as an index for product stability and quality, but also for their impact on public health. This review analyzes the scientific evidence gathered so far on the presence and role of biogenic amines in meat and meat products, also considering the effect of technological conditions on BAs accumulation or decrease. The data provided can be useful for developing solutions to control BAs formation during the shelf-life, for example by novel starters for dry cured products, as well as by packaging technologies and materials for fresh meats. Further research, whose trends are reviewed in this paper, will fill the knowledge gaps, and allow us to protect such perishable products along the distribution chain and in the home environment.