Decarboxylase Enzyme Activity Research Articles

Identification and Characterization of Polyamine Metabolism in Citrus in Response to 'Candidatus Liberibacter asiaticus' Infection.

Citrus Huanglongbing, one of the most devastating citrus diseases, is caused by 'Candidatus Liberibacter asiaticus' (CLas). Polyamines are aliphatic nitrogen-containing compounds that play important roles in disease resistance and are synthesized primarily by two pathways: an arginine decarboxylation pathway and an ornithine decarboxylation pathway. However, it is unclear whether polyamines play a role in the tolerance of citrus to infection by CLas and, if so, whether one or both of the core polyamine metabolic pathways are important. We used high-performance liquid chromatography and ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry to detect the contents of nine polyamine metabolism-related compounds in six citrus cultivars with varying levels of tolerance to CLas. We also systematically detected the changes in polyamine metabolism-related compounds and H2O2 contents and compared the gene expression levels and the activities of enzymes involved in the polyamine metabolic pathway among healthy, asymptomatic, and symptomatic leaves of Newhall navel oranges infected with CLas. The tolerant and moderately tolerant varieties showed higher polyamine metabolism-related compound levels than those of susceptible varieties. Compared with the healthy group, the symptomatic group showed significantly increased contents of arginine, ornithine, γ-aminobutyric acid, and putrescine by approximately 180, 19, 1.5, and 0.2 times, respectively, and upregulated expression of biosynthetic genes. Arginase and ornithine decarboxylase enzyme activities were the highest in the symptomatic group, whereas arginine decarboxylase and agmatine deiminase enzyme activities were the highest in the asymptomatic group. The two polyamine biosynthetic pathways showed different trends with the increase of the CLas titer, indicating that polyamines were mainly synthesized through the arginine decarboxylase pathway in the asymptomatic leaves and were synthesized via the ornithine decarboxylase pathway in symptomatic leaves. These findings provide new insight into the changes in polyamine metabolism in citrus infected with CLas.

Production of Histamine by Diverse Gut Bacteria Can Activate Intestinal HRH1 and Promote Calcium Mobilization

Background: Histamine is a biogenic amine that impacts several physiological processes, including allergic reactions, neurotransmitter activity and immune regulation. Bacteria uptake L-histidine and convert it into histamine via the activity of histidine decarboxylase enzymes. Histamine can also be produced by host cells such as enterochromaffn-like cells, mast cells and neurons. We hypothesized that a diverse group of bacteria would be capable of generating histamine. We predicted that histamine producing bacteria in the gut would activate intestinal epithelial histamine receptors and promote gut health. Methods and Results: To investigate how widespread histamine production is across bacterial species, we examined 102,018 annotated genomes in the Integrated Microbiome Genome Database. We found 3,679 bacterial genomes (3.6%) possessed histidine decarboxylase. We found histidine decarboxylase in bacteria belonged to 9 phyla: Bacillota, Bacteroidota, Actinomycetota, Pseudomonadota, Lentisphaerota, Fusobacteriota, Armatimonadota, Cyanobacteriota, and Verrucomicrobiota. Although the majority of the identified bacteria were aquatic and terrestrial in origin, ~14% of the bacteria were from the human gut microbiota. We confirmed the ability of several gut bacteria to generate histamine in a chemically defined bacterial growth medium using liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based targeted metabolomics. Briefly, histamine and histidine quantification is performed using authentic analytical and stable-label deuterated internal standard compounds that are used to produce calibration curves that span a linear dynamic range of 0.977-1,000 ng/mL. We found higher concentrations of histamine produced by gut-associated Klebsiella aerogenes, Fusobacterium varium, Clostridium perfringens, Limosilactobacillus reuteri and Morganella morganii. To address the question if bacterial-derived histamine could activate intestinal epithelial histamine receptors in the gut, we examined histamine receptors in publicly available single cell RNAseq datasets. We found that HRH1 was expressed in all cell types of the small and large intestine. We did not observe any expression of HRH2, HRH3 or HRH4 in the gut epithelium. We confirmed this finding in human intestinal organoids derived from duodenum, jejunum, ileum and colon. HRH1 activation in airway epithelial cells is known to signal through MAPK and promote pro-inflammatory cytokine release. Using GCaMP6S transduced organoids, we found that multiple concentrations of histamine stimulated robust calcium mobilization. However, histamine did not alter the levels of phosphorylated MAPK members p38, JNK, ERK, CREB or AKT and did not stimulate the release of any of the 18 epithelial specific cytokines we examined. Conclusions: Our work reveals that gut bacteria are capable of generating histamine, and histamine in the gut can activate epithelial HRH1 to drive calcium signaling and other downstream signals. K01 DK123195 (M Engevik) K01 DK121869 (A Engevik F32 DK130288 (K Engevik) APS Postdoctoral Fellowship (K Engevik). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Geraniol attenuates behavioral and neurochemical impairments by inhibitions of HPA-axis and oxido-inflammatory perturbations in mice exposed to post-traumatic stress disorder

Geraniol is an acyclic isoprenoid monoterpenoid analogue that has been shown to elicit neuroprotective functions, primarily through its ability to stimulate antioxidant and anti-inflammatory systems. An increase in inflammatory cytokines and oxidative stress exacerbate activation hypothalamic-pituitary-adrenal axis (HPA), leading to neurochemical dysfunction, which has important roles in the pathogenesis of post-traumatic disorder (PTSD), a mental health disorder characterized of post-trauma-induced intense fear. The aim of this study was to evaluate the anti-PTSD-like effects and underlying mechanisms of geraniol against single-prolonged-stress (SPS)-induced PTSD in mice. Following concomitant exposure to SPS (triple-paradigm traumatic events) and isolation for 7 days, mice (n = 9) were treated with geraniol (50 and 100 mg/kg, p.o.) or fluoxetine (10 mg/kg, p.o.) from days 8–21. Mice were assessed for behavioral changes. Neurochemical changes, inflammatory, oxido-nitrergic markers, adrenal weight, serum glucose and corticosterone concentrations were assayed. Geraniol inhibits SPS-induced anxiety- and depressive-like features as well as behavioral despair in the depression paradigms. SPS-induced locomotor and memory impairments were also abated by geraniol treatment similarly to fluoxetine. SPS-induced adrenal hypertrophy and increased blood glucose and corticosterone concentrations, were attenuated by the geraniol treatment. Elevated levels of TNF-α and IL-6, and malondialdehyde, nitrite, acetylcholinesterase enzyme were reduced by geraniol. Geraniol also increased glutathione, superoxide-dismutase, and catalase levels as well as dopamine, serotonin concentrations and GABAergic glutamic acid decarboxylase enzyme activity in the striatum, prefrontal cortex and hippocampus in the PTSD-mice relative to SPS control. In conclusion, geraniol attenuates behavioral impairments and neurochemical dysregulations by inhibitions of HPA-axis and oxido-inflammatory perturbations in mice exposed to PTSD.

Histamine and Tyramine in Chihuahua Cheeses during Shelf Life: Association with the Presence of tdc and hdc Genes.

Cheese is a product of animal origin with a high nutritional value, and it is one of the most consumed dairy foods in Mexico. In addition, Chihuahua cheese is the most consumed matured cheese in Mexico. In the production process of Chihuahua cheese, maturation is carried out by adding acid lactic microorganisms, mainly of the Lactococcus genus and, in some cases, also the Streptococcus and Lactobacillus genus. As part of the metabolism of fermenting microorganisms, biogenic amines can develop in matured foods, which result from the activity of amino decarboxylase enzymes. In cheeses, histamine and tyramine are the main amines that are formed, and the consumption of these represents a great risk to the health of consumers. In this work, the presence of biogenic amines (histamine and tyramine) was determined by HPLC at different times of the shelf life of Chihuahua cheeses. In addition, the presence of genes hdc and tdc that code for the enzymes responsible for the synthesis of these compounds (histidine and tyrosine decarboxylase, or HDC and TDC) was determined by molecular techniques. A significant correlation was observed between the presence of both histamine and tyramine at the end of shelf life with the presence of genes that code for the enzymes responsible for their synthesis.

Isolation and Identification of Tyramine-Producing Lactic Acid Bacteria from Fermented Olives

In the present study, we aimed to isolate and biochemically identify tyramine-producing lactic acid bacteria (LAB) from black and green fermented olive samples produced by traditional methods and obtained from different provinces of Turkey. A total of 36 LABs, including Enterococcus spp. (2 isolates), Lactobacillus spp. (16 isolates), and Lactococcus spp. (18 isolates) were isolated from the fermented olive samples. Among them, 27 isolates could decarboxylate tyrosine amino acid; however, the decarboxylase enzyme activity of the remaining 9 isolates was negative. The ability of LAB isolates with positive enzyme activity to produce tyramine was evaluated using high-performance liquid chromatography (HPLC), and 6 isolates were found to be significant tyramine producers in vitro, producing tyramine at concentrations ranging from 107.251 to 207.618 mg L–1.

Exogenous Hemin alleviated cadmium stress in maize (Zea mays L.) by enhancing leaf photosynthesis, AsA-GSH cycle and polyamine metabolism.

Cadmium (Cd) stress is one of the principal abiotic stresses that inhibit maize growth. The research was to explore (hemin chloride) Hemin (100 μmol L−1) on photosynthesis, ascorbic acid (AsA)-glutathione (GSH) cycle system, and polyamine metabolism of maize under Cd stress (85 mg L−1) using nutrient solution hydroponics, with Tiannong 9 (Cd tolerant) and Fenghe 6 (Cd sensitive) as experimental materials. The results showed that Hemin can increase leaf photosynthetic pigment content and ameliorate the ratio of Chlorophyll a/chlorophyll b (Chla/Chlb) under Cd stress. The values of ribose 1, 5-diphosphate carboxylase/oxygenase (RuBPcase) and phosphoenolpyruvate carboxylase (PEPCase), and total xanthophyll cycle pool [(violoxanthin (V), antiflavin (A) and zeaxanthin (Z)] increased, which enhancing xanthophyll cycle (DEPS) de-epoxidation, and alleviating stomatal and non-stomatal limitation of leaf photosynthesis. Hemin significantly increased net photosynthetic rate (Pn), stomatal conductance (gs), transpiration rate (Tr), photochemical quenching coefficient (qP), PSII maximum photochemical efficiency (Fv/Fm), and electron transfer rate (ETR), which contributed to the improvement of the PSII photosynthetic system. Compared with Cd stress, Hemin can reduce thiobartolic acid reactant (TBARS) content, superoxide anion radical (O2−) production rate, hydrogen peroxide (H2O2) accumulation, and the extent of electrolyte leakage (EL); decreased the level of malondialdehyde (MDA) content and increased the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT); slowed the decrease in dehydroascorbic acid reductase (DHAR) and monodehydroascorbate reductase (MDHAR) activity and the increase in glutathione reductase (GR) and ascorbate peroxidase (APX) activity in leaves; promoted the increase in AsA and GSH content, decreased dehydroascorbic acid (DHA) and oxidized glutathione (GSSG), and increased AsA/DHA and GSH/GSSG ratios under Cd stress. Hemin promoted the increase of conjugated and bound polyamine content, and the conversion process speed of free putrescine (Put) to free spermine (Spm) and spermidine (Spd) in maize; decreased polyamine oxidase (PAO) activity and increased diamine oxidase (DAO), arginine decarboxylase (ADC), ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (SAMDC) enzyme activities in leaves under Cd stress.

Ferulic acid inhibits catamenial epilepsy through modulation of female hormones.

Approximately 40% of women with epilepsy experience perimenstrual seizure exacerbation, referred to as catamenial epilepsy. These seizures result from cyclic changes in circulating progesterone and estradiol levels and there is no effective treatment for this form of intractable epilepsy. We artificially increased progesterone levels and neurosteroid levels (pseudo-pregnancy) in adult Swiss albino female mice (19-23g) by injecting them with pregnant mares' serum gonadotropin (5 IU s.c.), followed by human chorionic gonadotropin (5 IU s.c.) after 46h. After this, ferulic acid (25, 50, 100mg/kg i.p.) treatment was given for 10 days. During treatment, progesterone, estradiol, and corticosterone levels were estimated in blood on days 1, 5, and 10. Neurosteroid withdrawal was induced by finasteride (50mg/kg, i.p.) on treatment day 9. Twenty-four hours after finasteride administration (day 10 of treatment), seizure susceptibility was evaluated with the sub-convulsant pentylenetetrazol (PTZ) dose (40mg/kg i.p.). Four to six hours after PTZ, animals were assessed for depression like phenotypes using tail-suspension test (TST). Four to six hours following TST, animals were euthanized, and discrete brain parts (cortex and hippocampus) were separated for estimation of norepinephrine, serotonin, and dopamine as well as glutamic acid decarboxylase (GAD) enzyme activity. PMSG and HCG treatment elevated progesterone and estradiol levels, assessed on days 1, 5, and 10 causing a state of pseudo-pregnancy. Treatment with finasteride increased seizure susceptibility and depression-like characteristics possibly due to decreased progesterone and elevated estrogen levels coupled with decreased monoamine and elevated corticosterone levels. Ferulic acid treatment, on the other hand, significantly decreased seizure susceptibility and depression like behavior, possibly because of increased progesterone, restored estradiol, corticosterone, monoamines, and GAD enzyme activity. We concluded anticonvulsant effect of ferulic acid in a mouse model of catamenial epilepsy, evidenced by favourable seizure attenuation and curative effect on the circulating progesterone, estradiol, and corticosterone levels along with restorative effect on GAD enzyme activity and monoamine levels.

Hydrogen Sulfide Mitigates Chilling Injury of Postharvest Banana Fruits by Regulating γ-Aminobutyric Acid Shunt Pathway and Ascorbate-Glutathione Cycle.

This study aimed to determine the effect of hydrogen sulfide on chilling injury (CI) of banana (Musa spp.) during cold storage (7°C). It was observed that hydrogen sulfide application (2 mmol L–1) markedly reduced the CI index and showed significantly higher chlorophyll contents, along with suppressed chlorophyll peroxidase and chlorophyllase enzyme activity. The treated banana fruits exhibited substantially higher peel lightness (L*), along with significantly a lower browning degree and soluble quinone content. The treated bananas had substantially a higher endogenous hydrogen sulfide content and higher activity of its biosynthesis-associated enzymes such as D-cysteine desulfhydrase (DCD) and L-cysteine desulfhydrase (LCD), along with significantly lower ion leakage, lipid peroxidation, hydrogen peroxide, and superoxide anion concentrations. Hydrogen sulfide-treated banana fruits showed an increased proline content and proline metabolism-associated enzymes including ornithine aminotransferase (OAT), Δ1-pyrroline-5-carboxylate synthetase (P5CS), and proline dehydrogenase (PDH). In the same way, hydrogen sulfide-fumigated banana fruits accumulated higher endogenous γ-aminobutyric acid (GABA) due to enhanced activity of glutamate decarboxylase (GAD) and GABA transaminase (GABA-T) enzymes. The hydrogen sulfide-treated fruits exhibited higher total phenolics owing to lower polyphenol oxidase (PPO) and peroxidase (POD) activity and stimulated phenylalanine ammonia lyase (PAL). The treated banana exhibited higher ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR), and superoxide dismutase (SOD) activity, along with higher glutathione (GSH) and ascorbic acid (AsA) concentrations and a significantly lower dehydroascorbic acid (DHA) content. In conclusion, hydrogen sulfide treatment could be utilized for CI alleviation of banana fruits during cold storage.

Postharvest γ-aminobutyric acid application mitigates chilling injury of aonla (Emblica officinalis Gaertn.) fruit during low temperature storage

Aonla is a nutrients rich underutilized subtropical fruit. It has short shelf life and is prone to chilling injury (CI) below 6 °C. So, the effect of γ-aminobutyric acid [5 mmol L−1 (GABA)] was investigated on aonla fruit CI mitigation during low temperature storage at 5 ± 1 °C for 24 d. Results showed that GABA treatment markedly suppressed CI, decay incidence, membrane permeability, malondialdehyde, superoxide anion and hydrogen peroxide in contrast with control. Treated fruit showed higher activity of glutamate decarboxylase (GAD) and GABA transaminase (GABA-T) enzymes which ultimately resulted in increased endogenous GABA content accumulation. Similarly, GABA application stimulated the activities of Δ1-pyrroline-5-carboxylate synthetase (P5CS) and ornithine aminotransferase (OAT) enzymes which thus enhanced proline accumulation. The GABA treated fruit exhibited higher phenylalanine ammonia lyase (PAL) and reduced polyphenol oxidase (PPO) enzyme activity and showed higher total phenols accumulation. In addition, total flavonoids, ascorbic acid and glutathione content were also significantly higher in GABA treated aonla fruit. In addition, GABA treated aonla fruit exhibited markedly higher ascorbate peroxidase (APX) catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) activities in comparison with the control. In addition, GABA treated fruit showed lower total soluble solids, ripening index and juice pH along with markedly higher concentration of titratable acidity. In conclusion, GABA treatment could be used for CI mitigation and overall quality maintenance of cold stored aonla fruit.

Computational analysis of non-synonymous single nucleotide polymorphism in UROD gene linked with familial Porphyria Cutanea Tarda

Porphyria Cutanea Tarda (PCT) is the most common type of human porphyria, characterized by onycholysis and blisters on the skin. It is a multifactorial disorder, mainly characterized by reduced uroporphyrinogen decarboxylase enzyme activity. Non-synonymous single nucleotide polymorphisms (nsSNPs) in UROD gene resulted in amino acid sequence alteration in protein product. Previous studies have reported that nsSNPs in UROD gene linked with familial PCT. The preliminary aim of current study is to evaluate the effect of nsSNPs on structure and function of UROD enzyme by developing the secondary and tertiary structures, computationally. Out of 294 nsSNPs, 115 nsSNPs within the coding region have been analyzed as deleterious by means of all evaluated tools, suggesting their involvement in downregulation of UROD gene expression and its protein product functioning. In future, the current study would be used to perform in-vitro analysis of reported nsSNPs, which ultimately lead towards the effective drug designing strategies.

Melatonin treatment induces chilling tolerance by regulating the contents of polyamine, γ-aminobutyric acid, and proline in cucumber fruit

The mechanism of melatonin (MT) induced chilling tolerance in harvested cucumber fruit was investigated at commercial maturity. In this study, cucumber fruits were treated with 100 µmol L–1 MT at 4°C and 90% relative humidity for 15 d of storage. In comparison with the control, cucumber treatment with MT resulted in reduced chilling injury (CI), decreased electrolyte leakage and enhanced firmness. The fruits treated with MT showed higher chlorophyll contents in storage conditions with suppressed chlorophyllase enzyme activity. MT treatment increased arginine decarboxylase (ADC) and ornithine decarboxylase (ODC) enzyme activities. Moreover, enhanced expression of the Cucumis sativus ADC (CsADC) and C. sativus ODC (CsODC) genes resulted in the accumulation of polyamine contents. Similarly, proline levels exhibited higher levels among treated fruits. Meanwhile, the proline synthesizing enzymes △1-pyrroline-5-carboxylate syntheses (P5CS) and ornithine aminotransferase (OAT) were significantly increased, while a catabolic enzyme of proline dehydrogenase (PDH) activity was inhibited by treatment. In addition, MT induced expression of C. sativus OAT (CsOAT) and C. sativus P5CS (CsP5CS) genes. Cucumber fruits treated with MT also exhibited higher γ-aminobutyric acid (GABA) content by enhanced GABA transaminase (GABA-T) and glutamate decarboxylase (GAD) enzyme activities and a higher C. sativus GAD (CsGAD) gene expression. To sum up, the results show that MT treatment enhanced chilling tolerance, which was associated with the regulation of polyamines, as well as proline and γ-aminobutyric acid.

Optimization of γ-Aminobutyric Acid (GABA) Accumulation in Germinating Adzuki Beans (Vigna angularis) by Vacuum Treatment and Monosodium Glutamate, and the Molecular Mechanisms.

This study aimed to investigate the optimal hypoxic and monosodium glutamate (MSG) stress conditions for the enrichment of γ-Aminobutyric acid (GABA) in germinating adzuki beans and to reveal the potential underlying molecular mechanisms of GABA accumulation. Using single-factor experiments and response surface model, we investigated the effects of germination time, germination temperature, vacuum time, and MSG concentration on GABA contents, and further explored the activity and gene expression of glutamate decarboxylase (GAD) and polyamine oxidase (PAO) critical rate restriction enzymes during GABA synthesis. The optimal soaking temperature, soaking time, and pH conditions were 35°C, 16 h, and 5, respectively. Furthermore, the optimal germination conditions for optimal GABA enrichment were 48 h, 1.99 mg/ml MSG concentration, germination temperature of 31.49°C, and vacuum time of 15.83 h. Under such conditions, the predicted GABA concentration was 443.57 ± 7.18 mg/100 g, with no significant difference between the predicted and experimental data. The vacuum + MSG (FZM) treatment has a maximum contribution rate of GABA to 38.29%, which significantly increase GABA content, and the increase was associated with increased GAD and PAO activity. In addition, MSG in combination with vacuum treatment could significantly induce VaGAD4 and VaGAD6 genes in 2 days germination of adzuki beans. According to the results of the present study, vacuum + MSG treatment is an effective approach to enhancing GABA accumulation in germinating adzuki beans, which could be employed in enhancing the functional quality of germinating adzuki beans.

3-O-Acetyl-11-keto-β-boswellic acid ameliorates chronic unpredictable mild stress induced HPA axis dysregulation in relation with glutamate/GABA aberration in depressive rats.

Overt expression of brain glucocorticoid receptor (GR) leads to elevation of glutamate release causes cerebral excitotoxicity which in turn produce neuropsychological disorders. The aim of our work is to study the consequence of 3-O-Acetyl-11-keto-β-boswellic acid (AKBA) on chronic unpredictable mild stress (CUMS) induced HPA axis dysregulation in relative to glutamate and GABA irregularity in depressive rats. AKBA (5, 10 &15mg/kg) was administered for 28days parallel with CUMS induction in rats. Behavioural studies, tail suspension test (TST), open field exploratory (OFT) and forced swim test (FST) were performed. Biochemical studies including plasma corticosterone, glutamate GABA and glutamic acid decarboxylase (GAD) enzyme activity were studied. Glucocorticoid receptor expression and brain histology were studied to observe the effect of AKBA. CUMS induction results in depressive state of the animals were confirmed by the sucrose preference test. The administration of AKBA significantly reduced the immobility time and improved the exploratory behaviour. Plasma corticosterone and brain glutamate level was decreased and GABA level were increased significantly evident with GAD activation in AKBA-treated animals, further confirmed with decreased GR expression improves architecture of prefrontal cortex region. Correlation study illustrates behavioural improvements undeviating the biochemical alteration and GR expression after AKBA treatment during depression. AKBA significantly reversed the CUMS-induced glutamate/GABA abnormalities through the adaptation of central HPA axis regulation. Hence this study concludes that AKBA can be a better alternative to treat depressive disorders.

Effects of wild type lactic acid bacteria on histamine and tyramine formation in sucuk

Biogenic amines (BAs) are formed by the decarboxylation of amino acids in fermented products and accumulate in these products due to the fermentation conditions, the natural microflora of the product, and the diversity of amino acids. Although they are inhibited by the human body, they are a hazard to public health. Starter cultures used in fermented sucuk should not have amino acid decarboxylase properties. The aim of the present study was to determine proteolytic activity, histidine and tyrosine decarboxylase enzyme activities of Lactobacillus plantarum, Lactobacillus sake, and Lactobacillus curvatus species and to evaluate the level of BA in sucuk groups containing these lactic acid bacteria (LAB). It was determined that none of the LAB generated these activities. While histamine values were not statistically significant in the sucuk groups (P> 0.05), tyramine values showed statistically significant differences (P<0.05). The tyramine values of GI ( = 1.43 ± 0.75) and GIII ( = 2.73 ± 1.02) groups were lower than C ( = 8.97 ± 5.29) and GII ( = 7.58 ± 2.90) groups. According to the results of the study, L. plantarum or L. curvatus can provide more reliable fermented products with respect to tyramine formation. L. plantarum, L. sake, and L. curvatus could reduce histamine and tyramine formation in fermented sucuk.

AdRAP2.3, a Novel Ethylene Response Factor VII from Actinidia deliciosa, Enhances Waterlogging Resistance in Transgenic Tobacco through Improving Expression Levels of PDC and ADH Genes.

APETALA2/ethylene-responsive factor superfamily (AP2/ERF) is a transcription factor involved in abiotic stresses, for instance, cold, drought, and low oxygen. In this study, a novel ethylene-responsive transcription factor named AdRAP2.3 was isolated from Actinidia deliciosa ‘Jinkui’. AdRAP2.3 transcription levels in other reproductive organs except for the pistil were higher than those in the vegetative organs (root, stem, and leaf) in kiwi fruit. Plant hormones (Salicylic acid (SA), Methyl-jasmonate acid (MeJA), 1-Aminocyclopropanecarboxylic Acid (ACC), Abscisic acid (ABA)), abiotic stresses (waterlogging, heat, 4 °C and NaCl) and biotic stress (Pseudomonas Syringae pv. Actinidiae, Psa) could induce the expression of AdRAP2.3 gene in kiwi fruit. Overexpression of the AdRAP2.3 gene conferred waterlogging stress tolerance in transgenic tobacco plants. When completely submerged, the survival rate, fresh weight, and dry weight of transgenic tobacco lines were significantly higher than those of wile type (WT). Upon the roots being submerged, transgenic tobacco lines grew aerial roots earlier. Overexpression of AdRAP2.3 in transgenic tobacco improved the pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) enzyme activities, and improved the expression levels of waterlogging mark genes NtPDC, NtADH, NtHB1, NtHB2, NtPCO1, and NtPCO2 in roots under waterlogging treatment. Overall, these results demonstrated that AdRAP2.3 might play an important role in resistance to waterlogging through regulation of PDC and ADH genes in kiwi fruit.

Tuna Can Harbor Histamine-Producing Bacteria

Tuna fish may carry bacteria that, even at lowered temperatures, grow and retain histidine decarboxylase (HDC) enzyme activity, raising questions about the potential for those enzymes producing histamines in refrigerated fresh tuna, according to Kristin Bjornsdottir-Butler, of the Gulf Coast Seafood Laboratory, a Food and Drug Administration research facility on Dauphin Island, Ala., and her collaborators. These cold-tolerant, histamine-producing bacteria are indigenous to the fish, not contaminants introduced during handling, the researchers note. Details appeared 29 January 2016 in Applied and Environmental Microbiology (doi:10.1128/AEM.02833–15/).

Biogenic amines in seafood: a review.

The biogenic amines are low molecular weight organic bases present normally in the body with biological activity influencing important physiological functions. The physiological functions of these molecules are achieved by very low concentrations in the tissues. However, significantly high amounts of biogenic amines are produced during processing and storage of seafood as a result of microbial contamination and inadequate storage conditions. Microorganisms having decarboxylase enzyme activity convert amino acids to their respective biogenic amines. Biogenic amines in seafood have been implicated as a major causative agent of food borne illness, where intoxication results from the ingestion of foods containing higher amount of biogenic amines. Hence its identification, quantitation and awareness of this food borne toxin are important in relation to food safety and spoilage. The aim of this paper is to review the basic concepts of seafood quality and safety in relation to biogenic amines along with its control measures and future areas for research.

Combination treatment for allergic conjunctivitis – Plant derived histidine decarboxylase inhibitor and H1 antihistaminic drug

Aim of present investigation was to study the effect of catechin and the combination of catechin and cetirizine in ovalbumin induced animal model of allergic conjunctivitis. Guinea pigs were divided into 5 groups: normal control, disease control, disease treated with catechin 100 mg/kg, disease treated with cetirizine 10 mg/kg, disease treated with combination of catechin and cetirizine, 50 mg/kg & 5 mg/kg respectively. Sensitization was carried out by intraperitoneal injection of ovalbumin for the period of 14 day. Simultaneously, catechin was administered orally for 14 days while, cetirizine was administered at the day of experiment. Determination of clinical scoring, mast cell and blood histamine content, histidine decarboxylase activity from stomach was carried out. Vascular permeability was measured by dye leakage after secondary challenge of allergen and conjunctival tissues were subjected for histopathological examinations. Treatment with catechin, cetirizine and combination showed significant (P < 0.05) decrease in clinical scoring and vascular permeability. While, catechin 100 mg/kg and catechin 50 mg/kg showed significant (P < 0.05) decrease in histamine content in mast and blood. The treatment also showed significant (P < 0.05) decrease in the histidine decarboxylase enzyme activity. However, cetirizine group did not show any difference in enzyme activity as well as histamine content. Histopathological examination also showed improvement in ulceration and decrease in edema and inflammation in all treatment groups. From the present study, we can conclude that catechin exhibits potent anti-allergic activity by histidine decarboxylase enzyme inhibition and combination shown significant anti-allergic activity at reduced dose by both enzyme inhibition as well as inhibition of histamine receptors.

Relation between coumarate decarboxylase and vinylphenol reductase activity with regard to the production of volatile phenols by native Dekkera bruxellensis strains under ‘wine-like’ conditions

Dekkera/Brettanomyces bruxellensis is considered a major cause of wine spoilage, and 4-ethylphenol and 4-ethylguaiacol are the most abundant off-aromas produced by this species. They are produced by decarboxylation of the corresponding hydroxycinnamic acids (HCAs), followed by a reduction of the intermediate 4-vinylphenols. The aim of the present study was to examine coumarate decarboxylase (CD) and vinylphenol reductase (VR) enzyme activities in 5 native D. bruxellensis strains and determine their relation with the production of ethylphenols under ‘wine-like’ conditions. In addition, biomass, cell culturability, carbon source utilization and organic acids were monitored during 60days. All strains assayed turned out to have both enzyme activities. No significant differences were found in CD activity, whilst VR activity was variable among the strains. Growth of D. bruxellensis under ‘wine-like’ conditions showed two growth phases. Sugars were completely consumed during the first growth phase. Transformation of HCAs into ethylphenols also occurred during active growth of the yeast. No statistical differences were observed in volatile phenol levels produced by the strains growing under ‘wine-like’ conditions, independently of the enzyme activity previously recorded. Furthermore, our results demonstrate a relationship between the physiological state of D. bruxellensis and its ability to produce ethylphenols. Inhibition of growth of D. bruxellensis in wine seems to be the most efficient way to avoid ethylphenol production and the consequent loss of wine quality.

Waterlogging-induced changes in fermentative metabolism in roots and nodules of soybean genotypes

Waterlogging blocks the oxygen supply to the root system which inhibits respiration, and greatly reduces the energy status of cells that affect important metabolic processes. This study evaluated fermentative metabolism and carbohydrate contents in the root system of two soybean (Glycine max L. Merril) genotypes under hypoxic and post-hypoxic conditions. Nodulated plants (genotypes Fundacep 53 RR and BRS Macota) were grown in vermiculite and transferred to a hydroponic system at the reproductive stage. The root system was submitted to hypoxia by flowing N2 (nitrogen) gas in a solution for 24 and 72 h. For recovery, plants returned to normoxia condition by transfer to vermiculite for 24 and 72 h. Fermentative enzyme activity, levels of anaerobic metabolites and carbohydrate content were all quantified in roots and nodules. The activity of alcohol dehydrogenase, pyruvate decarboxylase and lactate dehydrogenase enzymes, as well as the content of ethanol and lactate, increased with hypoxia in roots and nodules, and subsequently returned to pre-hypoxic levels in the recovery phase in both genotypes. Pyruvate content increased in nodules and decreased in roots. Sugar and sucrose levels increased in roots and decreased in nodules under hypoxia in both genotypes. Fundacep RR 53 was more responsive to the metabolic effects caused by hypoxia and post-hypoxia than BRS Macota, and it is likely that these characteristics contribute positively to improving adaptation to oxygen deficiency.