Characterizing arginine, ornithine, and putrescine pathways in enteric pathobionts.

Arginine-ornithine metabolism plays a crucial role in bacterial homeostasis, as evidenced by numerous studies. However, the utilization of arginine and the downstream products of its metabolism remain undefined in various gut bacteria. To bridge this knowledge gap, we employed genomic screening to pinpoint relevant metabolic targets. We also devised a targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) metabolomics method to measure the levels of arginine, its upstream precursors, and downstream products in cell-free conditioned media from enteric pathobionts, including Escherichia coli, Klebsiella aerogenes, K. pneumoniae, Pseudomonas fluorescens, Acinetobacter baumannii, Streptococcus agalactiae, Staphylococcus epidermidis, S. aureus, and Enterococcus faecalis. Our findings revealed that all selected bacterial strains consumed glutamine, glutamate, and arginine, and produced citrulline, ornithine, and GABA in our chemically defined medium. Additionally, E. coli, K. pneumoniae, K. aerogenes, and P. fluorescens were found to convert arginine to agmatine and produce putrescine. Interestingly, arginine supplementation promoted biofilm formation in K. pneumoniae, while ornithine supplementation enhanced biofilm formation in S. epidermidis. These findings offer a comprehensive insight into arginine-ornithine metabolism in enteric pathobionts.

CsCuAO1 Associated with CsAMADH1 Confers Drought Tolerance by Modulating GABA Levels in Tea Plants.

Our previous study showed that COPPER-CONTAINING AMINE OXIDASE (CuAO) and AMINOALDEHYDE DEHYDROGENASE (AMADH) could regulate the accumulation of γ-aminobutyric acid (GABA) in tea through the polyamine degradation pathway. However, their biological function in drought tolerance has not been determined. In this study, Camellia sinensis (Cs) CsCuAO1 associated with CsAMADH1 conferred drought tolerance, which modulated GABA levels in tea plants. The results showed that exogenous GABA spraying effectively alleviated the drought-induced physical damage. Arabidopsis lines overexpressing CsCuAO1 and CsAMADH1 exhibited enhanced resistance to drought, which promoted the synthesis of GABA and putrescine by stimulating reactive oxygen species' scavenging capacity and stomatal movement. However, the suppression of CsCuAO1 or CsAMADH1 in tea plants resulted in increased sensitivity to drought treatment. Moreover, co-overexpressing plants increased GABA accumulation both in an Agrobacterium-mediated Nicotiana benthamiana transient assay and transgenic Arabidopsis plants. In addition, a GABA transporter gene, CsGAT1, was identified, whose expression was strongly correlated with GABA accumulation levels in different tissues under drought stress. Taken together, CsCuAO1 and CsAMADH1 were involved in the response to drought stress through a dynamic GABA-putrescine balance. Our data will contribute to the characterization of GABA's biological functions in response to environmental stresses in plants.

Selenium treatment alters the accumulation of osmolytes in arsenic-stressed rice (Oryza sativa L.).

Arsenic (As), one of the major pollutants in the soil, is an important environmental concern as its consumption can cause adverse health symptoms in living organisms. Its contamination of rice grown over As-contaminated areas is a serious concern in South Asian countries. Selenium (Se) has been reported to influence various osmolytes under metal stress in plants. The present study reports the role of Se in mitigating As stress in rice by modulating osmolyte metabolism. Rice plants grown in As-amended soil (2.5-10 mg kg-1) in pots were treated with sodium selenate (0.5-1.0 mg Se kg-1 soil) in glass house conditions and leaf samples were collected at 60 and 90 days after sowing (DAS). As-treated rice leaves displayed a reduction in relative water content (RWC) and dry weight than control with a maximum reduction of 1.68- and 2.47-fold in RWC and 1.95- and 1.69-fold in dry weight in As10 treatment at 60 and 90 DAS, respectively. Free amino acids (1.38-2.26-fold), proline (3.88-3.93-fold), glycine betaine (GB) (1.27-1.72-fold), choline (1.67-3.1-fold), total soluble sugars (1.29-1.61-fold), and reducing sugars (1.67-2.19-fold) increased in As-treated rice leaves as compared to control at both stages. As stress increased the γ-aminobutyric acid (GABA), putrescine content, and glutamate decarboxylase activity whereas diamine oxidase and polyamine oxidase activities declined by 1.69-1.88-fold and 1.52-1.86-fold, respectively. Se alone or in combination with As improved plant growth, RWC, GB, choline, putrescine, and sugars; lowered proline and GABA; and showed a reverse trend of enzyme activities related to their metabolism than respective As treatments. As stress resulted in a higher accumulation of osmolytes to combat its stress which was further modulated by the Se application. Hence, the current investigation suggested the role of osmoprotectants in Se-induced amelioration of As toxicity in rice plants.

Polyamines and hormesis: Making sense of a dose response dichotomy.

The diverse biological effects of polyamines (putrescine, spermidine and spermine) were reviewed in the context of hormesis in an integrative manner for the first time. The findings illustrate that each of these polyamines commonly induces hormetic dose responses in a wide range of biological models and types of cells for multiple endpoints in numerous plant species and animal models. Plant research emphasized preconditioning experimental studies in which the respective polyamines conferred some protection against the damaging effects of a broad range of environmental stressors such as drought, salinity, cold/heat, heavy metals and UV-damage in an hormetic manner. Polyamine-based animal hormesis studies emphasized biomedical endpoints such as longevity and neuroprotection. These findings have important biological and biomedical implications and should guide experimental designs of low dose investigations.

Exogenous Putrescine Changes Biochemical (Antioxidant Activity, Polyphenol, Flavonoid, and Total Phenol Compounds) and Essential Oil Constituents of Salvia officinalis L.

Polyamines are small polycationic molecules containing amines that are present in almost all cells of living organisms and act in a wide range of physiological processes, growth, and development, biological and protection of cells against free radicals. This research is based on principal component analysis (PCA) and calculation of selection criteria (SC) to investigate the effect of foliar spraying of polyamine putrescine on essential oil yield, essential oil compounds, antioxidant activity, and biochemical compounds (polyphenol, flavonoid, and total phenol compounds) of Salvia officinalis. The treatments used included four levels of putrescine, Put (Control: 0, Put1: 500, Put2: 1000, and Put3: 1500 mg L-1 ) with five replications. Based on our results, four factors had eigenvalues≥1 and showed a cumulative variance percentage of 92.57 % by applying different concentrations of putrescine. According to the results of this research, putrescine had significant effects on the amount of total phenolic compounds, flavonoids, and antioxidant activity. The best attention to improving the essential oil yield of sage was 1000 mg L-1 . The crucial essential oil compounds of different Put treated sage were: cis-thujone (35.34 %), camphor (15.60 %), trans-thujone (9.90 %), 1,8-cineole (9.46 %), α-humulene (3.85 %), viridiflorol (3.62 %), camphene (3.58 %), α-pinene (3.50 %), ß-pinene (2.78 %), and limonene (1.23 %). The results showed that the amount of total phenol, the phenolic composition of catechin, and the antioxidant activity of sage plant extract increased significantly when putrescine was used at 1000 mg/liter. Results can use the current research to optimize the production management of medicinal plants and improve the quality of their products. In addition, the advantage of using putrescine is that it increases antioxidants and reduces oxidative damage, and can replace medicinal plants as suitable natural preservatives, thus improving food quality and safety.

Influence of lactic acid fermentation on the microbiological parameters, biogenic amines, and volatile compounds of bovine colostrum.

In this study we hypothesized that the relations between the bovine colostrum (BC) microbiota, biogenic amine (BA) as well as volatile compound (VC) profiles can lead to new deeper insights concerning the BC changes during the biological preservation. To implement such an aim, BC samples were collected from 5 farms located in Lithuania and fermented with Lactiplantibacillus plantarum and Lacticaseibacillus paracasei strains. Nonfermented and fermented BC were subjected to microbiological [lactic acid bacteria (LAB), Escherichia coli, and total bacteria (TBC), total Enterobacteriaceae (TEC) and total mold and yeast (M-Y) viable counts] and physicochemical (pH, color coordinates, BA content and VC profile) parameters evaluation, and the relationship between the tested parameters were also further analyzed. In comparison pH and dry matter (DM) of nonfermented samples, significant differences were not found, and pH of BC was, on average, 6.30, and DM, on average, 27.5%. The pH of fermented samples decreased, on average, until 4.40 in Lp. plantarum fermented group, and, on average, until 4.37 in Lc. paracasei fermented group. Comparing color characteristics among nonfermented BC groups, significant differences between lightness (L*) and yellowness (b*) were not detected, however, the origin (i.e., agricultural company), LAB strain used for fermentation and the interaction between these factors were statistically significant on BC redness (a*) coordinate. The microbial contamination among all the tested BC groups was similar. However, different LAB strains used for BC fermentation showed different effects toward the microbial contamination reduction, and specifically Lc. paracasei was more effective than Lp. plantarum strain. Predominant BA in BC were putrescine and cadaverine. The main VC in nonfermented and fermented BC were decane, 2-ethyl-1-hexanol, dodecane, 1,3-di-tert-butylbenzene, 3,6-dimethyldecane and tetradecane. Moreover, this study showed worrying trends with respect to the frozen colostrum storage, because most of the dominant VC in BC were contaminants from the packaging material. Additionally, significant correlations between separate VC and microbial contamination were obtained. Finally, these experimental results showed that the separate VC in BC can be an important marker for biological as well as chemical contamination of BC. Also, it should be pointed out that despite the fermentation with LAB is usually described as a safe and natural process with many advantages, control of BA in the end product is necessary.

Effect of putrescine supplementation to in vitro maturation medium on embryo development and quality in cattle.

This study aimed to investigate the effect of putrescine supplementation to maturation medium during in vitro embryo production in cattle on maturation and embryo development/quality. Oocytes obtained from the ovaries of Holstein cattle were used in the study. Obtained cumulus-oocyte complexes were evaluated according to morphological structure, cytoplasmic features, and cumulus cell number, and only Category-I ones were used in the study. Before the in vitro maturation step, oocytes were randomly divided into two groups. In the first group (Putrescine group, n = 159), 0.5 mM putrescine was added to the maturation medium before in vitro maturation. No addition was applied to the maturation medium of the second group (Control group, n = 149). Cumulus expansion degrees of oocytes following maturation (Grade I: poor, Grade II: partial, and Grade III: complete) were determined. In addition, the meiosis of oocytes after maturation was evaluated by differential staining. Then the oocytes were left for fertilization with sperm and finally, possible zygotes were transferred to the culture medium. After determining the developmental stages and quality of the embryos after in vitro culture, only the embryos at the blastocyst stage were stained with the differential staining method to determine the cell numbers. When the cumulus expansion degrees of the groups were evaluated, the Grade III cumulus expansion rate in the putrescine group was higher than the control group (74.21% and 60.4%; respectively) and the Grade I expansion rate (11.95% and 26.17%; respectively) was found lower (p < .05). When the resumption of meiosis was evaluated according to the cumulus expansion degrees, it was determined that the rate of resumption of meiosis increased as the cumulus expansion increased. In addition, the cleavage rates of oocytes and reaching the blastocyst in the putrescine group were found to be higher than in the control group (p < .05). Moreover, inner cell mass, trophectoderm cells, and total cell counts were found to be higher in blastocysts obtained after the putrescine supplementation to the maturation medium compared to the control group (p < .05). As a result, it was determined that the putrescine supplementation to the maturation medium during in vitro embryo production in cattle increased the degree of cumulus expansion and the rate of resumption of meiosis. In addition, putrescine supplementation was thought to increase the rate of reaching the blastocyst of oocytes due to better cell development in embryos.

High-Dose Spermidine Supplementation Does Not Increase Spermidine Levels in Blood Plasma and Saliva of Healthy Adults: A Randomized Placebo-Controlled Pharmacokinetic and Metabolomic Study.

(1) Background: Spermidine is a biogenic polyamine that plays a crucial role in mammalian metabolism. As spermidine levels decline with age, spermidine supplementation is suggested to prevent or delay age-related diseases. However, valid pharmacokinetic data regarding spermidine remains lacking. Therefore, for the first time, the present study investigated the pharmacokinetics of oral spermidine supplementation. (2) Methods: This study was designed as a randomized, placebo-controlled, triple-blinded, two-armed crossover trial with two 5-day intervention phases separated by a washout phase of 9 days. In 12 healthy volunteers, 15 mg/d of spermidine was administered orally, and blood and saliva samples were taken. Spermidine, spermine, and putrescine were quantified by liquid chromatography-mass spectrometry (LC-MS/MS). The plasma metabolome was investigated using nuclear magnetic resonance (NMR) metabolomics. (3) Results: Compared with a placebo, spermidine supplementation significantly increased spermine levels in the plasma, but it did not affect spermidine or putrescine levels. No effect on salivary polyamine concentrations was observed. (4) Conclusions: This study's results suggest that dietary spermidine is presystemically converted into spermine, which then enters systemic circulation. Presumably, the in vitro and clinical effects of spermidine are at least in part attributable to its metabolite, spermine. It is rather unlikely that spermidine supplements with doses <15 mg/d exert any short-term effects.

Putrescine supplementation shifts macrophage L-arginine metabolism related-genes reducing Leishmania amazonensis infection.

Leishmania is a protozoan that causes leishmaniasis, a neglected tropical disease with clinical manifestations classified as cutaneous, mucocutaneous, and visceral leishmaniasis. In the infection context, the parasite can modulate macrophage gene expression affecting the microbicidal activity and immune response. The metabolism of L-arginine into polyamines putrescine, spermidine, and spermine reduces nitric oxide (NO) production, favoring Leishmania survival. Here, we investigate the effect of supplementation with L-arginine and polyamines in infection of murine BALB/c macrophages by L. amazonensis and in the transcriptional regulation of genes involved in arginine metabolism and proinflammatory response. We showed a reduction in the percentage of infected macrophages upon putrescine supplementation compared to L-arginine, spermidine, and spermine supplementation. Unexpectedly, deprivation of L-arginine increased nitric oxide synthase (Nos2) gene expression without changes in NO production. Putrescine supplementation increased transcript levels of polyamine metabolism-related genes Arg2, ornithine decarboxylase (Odc1), Spermidine synthase (SpdS), and Spermine synthase (SpmS), but reduced Arg1 in L. amazonensis infected macrophages, while spermidine and spermine promoted opposite effects. Putrescine increased Nos2 expression without leading to NO production, while L-arginine plus spermine led to NO production in uninfected macrophages, suggesting that polyamines can induce NO production. Besides, L-arginine supplementation reduced Il-1b during infection, and L-arginine or L-arginine plus putrescine increased Mcp1 at 24h of infection, suggesting that polyamines availability can interfere with cytokine/chemokine production. Our data showed that putrescine shifts L-arginine-metabolism related-genes on BALB/c macrophages and affects infection by L. amazonensis.

Spermidine dietary supplementation and polyamines level in reference to survival and lifespan of honey bees.

Honey bee health has been an important and ongoing topic in recent years. Honey bee is also an important model organism for aging studies. Polyamines, putrescine, spermidine and spermine, are ubiquitous polycations, involved in a wide range of cellular processes such as cell growth, gene regulation, immunity, and regulation of lifespan. Spermidine, named longevity elixir, has been most analysed in the context of aging. One of the several proposed mechanisms behind spermidine actions is antioxidative activity. In present study we showed that dietary spermidine supplementation: (a) improved survival, (b) increased the average lifespan, (c) influenced the content of endogenous polyamines by increasing the level of putrescine and spermidine and decreasing the level of spermine, (d) reduced oxidative stress (MDA level), (e) increased the antioxidant capacity of the organism (FRAP), (f) increased relative gene expression of five genes involved in polyamine metabolism, and (g) upregulated vitellogenin gene in honey bees. To our knowledge, this is the first study on honey bee polyamine levels in reference to their longevity. These results provide important information on possible strategies for improving honey bee health by introducing spermidine into their diet. Here, we offer spermidine concentrations that could be considered for that purpose.

Novel Green Fluorescent Polyamines to Analyze ATP13A2 and ATP13A3 Activity in the Mammalian Polyamine Transport System.

Cells acquire polyamines putrescine (PUT), spermidine (SPD) and spermine (SPM) via the complementary actions of polyamine uptake and synthesis pathways. The endosomal P5B-type ATPases ATP13A2 and ATP13A3 emerge as major determinants of mammalian polyamine uptake. Our biochemical evidence shows that fluorescently labeled polyamines are genuine substrates of ATP13A2. They can be used to measure polyamine uptake in ATP13A2- and ATP13A3-dependent cell models resembling radiolabeled polyamine uptake. We further report that ATP13A3 enables faster and stronger cellular polyamine uptake than does ATP13A2. We also compared the uptake of new green fluorescent PUT, SPD and SPM analogs using different coupling strategies (amide, triazole or isothiocyanate) and fluorophores (symmetrical BODIPY, BODIPY-FL and FITC). ATP13A2 promotes the uptake of various SPD and SPM analogs, whereas ATP13A3 mainly stimulates the uptake of PUT and SPD conjugates. However, the polyamine linker and coupling position on the fluorophore impacts the transport capacity, whereas replacing the fluorophore affects polyamine selectivity. The highest uptake in ATP13A2 or ATP13A3 cells is observed with BODIPY-FL-amide conjugated to SPD, whereas BODIPY-PUT analogs are specifically taken up via ATP13A3. We found that P5B-type ATPase isoforms transport fluorescently labeled polyamine analogs with a distinct structure-activity relationship (SAR), suggesting that isoform-specific polyamine probes can be designed.

Ammonium improved cell wall and cell membrane P reutilization and external P uptake in a putrescine and ethylene dependent pathway.

Ammonium promotes rice P uptake and reutilization better than nitrate, under P starvation conditions; however, the underlying mechanism remains unclear. In this study, ammonium treatment significantly increased putrescine and ethylene content in rice roots under P deficient conditions, by increasing the protein content of ornithine decarboxylase and 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase compared with nitrate treatment. Ammonium treatment increased rice root cell wall P release by increasing pectin content and pectin methyl esterase (PME) activity, increased rice shoot cell membrane P release by decreasing phosphorus-containing lipid components, and maintained internal P homeostasis by increasing OsPT2/6/8 expression compared with nitrate treatment. Ammonium also improved external P uptake by regulating root morphology and increased rice grain yield by increasing the panicle number compared with nitrate treatment. The application of putrescine and ethylene synthesis precursor ACC further improved the above process. Our results demonstrate for the first time that ammonium increases rice P acquisition, reutilization, and homeostasis, and rice grain yield, in a putrescine- and ethylene-dependent manner, better than nitrate, under P starvation conditions.

Heterologous Expression and Characterization of Tea (Camellia sinensis) Polyamine Oxidase Homologs and Their Involvement in Stresses.

Polyamine oxidase (PAO) is a key enzyme maintaining polyamine homeostasis, which affects plant physiological activities. Until now, the gene members and function of PAOs in tea (Camellia sinenesis) have not been fully identified. Here, through the expression in Escherichia coli and Nicotiana benthamiana, we identified six genes annotated as CsPAO in tea genome and transcriptome and determined their enzyme reaction modes and gene expression profiles in tea cultivar 'Yinghong 9'. We found that CsPAO1,2,3 could catalyze spermine, thermospermine, and norspermidine, and CsPAO2,3 could catalyze spermidine in the back-conversion mode, which indicated that the precursor of γ-aminobutyric acid might originate from the oxidation of putrescin but not spermidine. We further investigated the changes of CsPAO activity with temperature and pH and their stability. Kinetic parameters suggested that CsPAO2 was the major PAO modifying polyamine composition in tea, and it could be inactivated by ß-hydroxyethylhydrazine and aminoguanidine. Putrescine content and CsPAO2 expression were high in tea flowers. CsPAO2 responded to wound, drought, and salt stress; CsPAO1 might be the main member responding to cold stress; anoxia induced CsPAO3. We conclude that in terms of phylogenetic tree, enzyme characteristics, and expression profile, CsPAO2 might be the dominant CsPAO in the polyamine degradation pathway.

The importance of the urea cycle and its relationships to polyamine metabolism during ammonium stress in Medicago truncatula.

The ornithine-urea cycle (urea cycle) makes a significant contribution to the metabolic responses of lower photosynthetic eukaryotes to episodes of high nitrogen availability. In this study, we compared the role of the plant urea cycle and its relationships to polyamine metabolism in ammonium-fed and nitrate-fed Medicago truncatula plants. High ammonium resulted in the accumulation of ammonium and pathway intermediates, particularly glutamine, arginine, ornithine, and putrescine. Arginine decarboxylase activity was decreased in roots, suggesting that the ornithine decarboxylase-dependent production of putrescine was important in situations of ammonium stress. The activity of copper amine oxidase, which releases ammonium from putrescine, was significantly decreased in both shoots and roots. In addition, physiological concentrations of ammonium inhibited copper amine oxidase activity in in vitro assays, supporting the conclusion that high ammonium accumulation favors putrescine synthesis. Moreover, early supplementation of plants with putrescine avoided ammonium toxicity. The levels of transcripts encoding urea-cycle-related proteins were increased and transcripts involved in polyamine catabolism were decreased under high ammonium concentrations. We conclude that the urea cycle and associated polyamine metabolism function as important protective mechanisms limiting ammonium toxicity in M. truncatula. These findings demonstrate the relevance of the urea cycle to polyamine metabolism in higher plants.

Epigenetic effect of putrescine supplementation during in vitro maturation of oocytes on offspring in mice.

PURPOSE: To investigate the epigenetic safety of putrescine supplementation during in vitro maturation (IVM) to offspring. METHODS: Germinal vesicle oocytes retrieved from 12-week-old mice were randomly divided into two groups and cultured in IVM medium with or without 1 mmol/L putrescine for 16 h. Then, in vitro fertilization and embryo transplantation were conducted to produce the F1 offspring. The F1 mated with ordinary mice and bred the F2 offspring. The DNA methylation patterns in the brain and heart of F1 were investigated by reduced representation bisulfite sequencing. Imprinted gene expression levels of F1 oocytes were tested. The global methylation of F2 was examined by dot blot. RESULTS: The weight, organ coefficient, and histology were normal in the F1 and F2 offspring from the putrescine-treated oocytes. An overall methylation level of 31.23 to 32.53% was observed for all CpG sites in the brain and heart of the two groups. The DNA methylation patterns of the brain and heart in F1 were not altered in general, with subtle differences. The expression levels of imprinted genes including H19, Snrpn, Peg3, Igf2, and Igf2r did not statistically change. The global 5mC level of F2 was consistent with the control group. CONCLUSION: Putrescine supplementation during IVM did not directly affect the development, health, and reproduction, and did not affect the genome and global epigenetics of mouse offspring derived from those oocytes. The transient putrescine treatment for improving oocyte maturation shows its long-term safety of genome and epigenetics in the offspring of mice.

Expression of polyamines and its association with GnRH-I in the hypothalamus during aging in rodent model.

GnRH-I and GnIH are the key neuropeptides that regulate the hypothalamic-pituitary-gonadal axis in mammals during aging. Polyamines are important aliphatic amines that are expressed in the brain and show variation with aging. The present study demonstrates evidence of variation in the level of expression of polyamines, GnRH-I and GnIH in the hypothalamus of female mice during aging. The study also suggests regulatory effects of polyamines over expression of the hypothalamic GnRH-I. The study shows a significant positive correlation between polyamines, its associated factors and GnRH-I along with significant negative correlation between polyamines, its associated factors and GnIH. This is the first study to report the effect of polyamines along with lactate or TNF-α or both on GnRH-I expression in GT1-7 cell line. TNF-α and lactate significantly decreased hypothalamic GnRH-I mRNA expression in GT1-7 cells when treated for 24 h. Polyamines (putrescine and agmatine) in contrast, significantly increased GnRH-I mRNA expression in GT1-7 cells when treated for 24 h. Also, polyamines increased GnRH-I mRNA expression when treated in presence of TNF-α or lactate thereby suggesting its neuro-protective role. This study also found 3809 differentially expressed genes through RNA-seq done between the hypothalamic GT1-7 cells treated with putrescine only versus TNF-α and putrescine. The present study suggests for the first time that putrescine treatment to TNFα-primed GT1-7 cells upregulates GnRH-I expression via regulation of several pathways such as calcium ion pathway, estrogen signaling, clock genes as well as regulating other metabolic process like neuronal differentiation and neurulation.

Putrescine is involved in root cell wall phosphorus remobilization in a nitric oxide dependent manner.

Phosphorus (P) deficiency is a key limited factor to affect the crop production in rice (Oryza sativa). Recently, accumulating evidences have shown that root cell wall P reutilization could be released to the cytoplasm to alleviate the P starvation and a set of plant hormone and signal molecules have been identified to be involved in it. However, the role of putrescine (Put) in this process is still unknown. In this study, we found that Put with a concentration of 0.001 mM, 0.01 mM and 0.1 mM increased the root and shoot biomass in Nipponbare (Nip) and Kasalath (Kas) under P deficiency, although only 0.1 mM Put could significantly elevated the root and shoot soluble P concentration in Nip. Exogenous 0.1 mM Put treatment reduced the root cell wall P content through increasing the pectin content and pectin methylesterase (PME) activity, indicating that Put can be involved in the root cell wall P reutilization under P starvation. In addition, Put treatment also stimulated the root-to-shoot translocation of P through upregulating the expression of PHOSPHORUS TRANSPORTER 2 (OsPT2) and OsPT8 that responsible for the long-distance transport. Put under P-deficient condition significantly enhanced the Nitric Oxide (NO) accumulation in root and the application of NO inhibitor carboxy-PTIO (cPTIO) could reverse the Put-alleviated P-deficient phenotype, suggesting this process is mediated by NO. In conclusion, our results demonstrated that Put acts upstream of NO to activate the root cell wall P remobilization in rice.

Exogenous putrescine attenuates the negative impact of drought stress by modulating physio-biochemical traits and gene expression in sugar beet (Beta vulgaris L.).

Drought tolerance is a complex trait controlled by many metabolic pathways and genes and identifying a solution to increase the resilience of plants to drought stress is one of the grand challenges in plant biology. This study provided compelling evidence of increased drought stress tolerance in two sugar beet genotypes when treated with exogenous putrescine (Put) at the seedling stage. Morpho-physiological and biochemical traits and gene expression were assessed in thirty-day-old sugar beet seedlings subjected to drought stress with or without Put (0.3, 0.6, and 0.9 mM) application. Sugar beet plants exposed to drought stress exhibited a significant decline in growth and development as evidenced by root and shoot growth characteristics, photosynthetic pigments, antioxidant enzyme activities, and gene expression. Drought stress resulted in a sharp increase in hydrogen peroxide (H2O2) (89.4 and 118% in SBT-010 and BSRI Sugar beet 2, respectively) and malondialdehyde (MDA) (35.6 and 27.1% in SBT-010 and BSRI Sugar beet 2, respectively). These changes were strongly linked to growth retardation as evidenced by principal component analysis (PCA) and heatmap clustering. Importantly, Put-sprayed plants suffered from less oxidative stress as indicated by lower H2O2 and MDA accumulation. They better regulated the physiological processes supporting growth, dry matter accumulation, photosynthetic pigmentation and gas exchange, relative water content; modulated biochemical changes including proline, total soluble carbohydrate, total soluble sugar, and ascorbic acid; and enhanced the activities of antioxidant enzymes and gene expression. PCA results strongly suggested that Put conferred drought tolerance mostly by enhancing antioxidant enzymes activities that regulated homeostasis of reactive oxygen species. These findings collectively provide an important illustration of the use of Put in modulating drought tolerance in sugar beet plants.

Progesterone and interferon tau regulate expression of polyamine enzymes during the ovine peri-implantation period†.

Progesterone (P4) and interferon tau (IFNT) are important for establishment and maintenance of pregnancy in ruminants. Agmatine and polyamines (putrescine, spermidine, and spermine) have important roles in the survival, growth, and development of mammalian conceptuses. This study tested the hypothesis that P4 and/or IFNT stimulate the expression of genes and proteins involved in the metabolism and transport of polyamines in the ovine endometrium. Rambouillet ewes (n = 24) were surgically fitted with intrauterine catheters on Day 7 of the estrous cycle. They received daily intramuscular injections of 50 mg P4 in corn oil vehicle and/or 75-mg progesterone receptor antagonist (RU486) in corn oil vehicle from Days 8-15, and twice daily intrauterine injections (25 µg/uterine horn/day) of either control serum proteins (CX) or IFNT from Days 11-15, resulting in four treatment groups: (i) P4 + CX; (ii) P4 + IFNT; (iii) RU486 + P4 + CX; or (iv) RU486 + P4 + IFNT. On Day 16, ewes were hysterectomized. The total amounts of arginine, citrulline, ornithine, agmatine, and putrescine in uterine flushings were affected (P < 0.05) by P4 and/or IFNT. P4 increased endometrial expression of SLC22A2 (P < 0.01) and SLC22A3 (P < 0.05) mRNAs. IFNT affected endometrial expression of MAT2B (P < 0.001), SAT1 (P < 0.01), and SMOX (P < 0.05) mRNAs, independent of P4. IFNT increased the abundance of SRM protein in uterine luminal (LE), superficial glandular (sGE), and glandular epithelia (GE), as well as MAT2B protein in uterine LE and sGE. These results indicate that P4 and IFNT act synergistically to regulate the expression of key genes required for cell-specific metabolism and transport of polyamines in the ovine endometrium during the peri-implantation period of pregnancy.

Arginine promotes testicular development in boars through nitric oxide and putrescine.

The present work aimed to explore the influence and underlying mechanisms involving arginine in testicular development in boars. To this end, thirty 30-day-old male Duroc piglets (7.00 ± 0.30 kg) were randomly sorted into two groups, maintained on either a basal diet (CON, n = 15) or a diet supplemented with 0.8% arginine (ARG, n = 15). Blood and testicular samples were collected during the experimental period to analyse amino acid composition and arginine metabolite levels. The results showed that dietary supplementation with arginine increased number of spermatogonia and height of the seminiferous epithelium (p < 0.05). Sperm density, total number and effective number of sperm of the boars in the ARG group increased significantly compared with those in the CON group (p < 0.05). Although arginine supplementation did not affect plasma amino acid levels, testicular arginine levels in 150-day-old boars exhibited a significant increase (p < 0.05). The level of serum nitric oxide (NO) and activity of nitric oxide synthase (NOS) also increased in 150-day-old boars in the ARG group (p < 0.05). Interestingly, dietary supplementation with arginine increased testicular levels of putrescine in 150-day-old boars (p < 0.05). These results indicated that arginine supplementation increased serum NO levels and testicular arginine and putrescine abundance, thereby improving testicular development and semen quality in boars.