Involvement of putrescine in osmotic stress-induced ABA signaling in leaves of wheat seedlings

To elucidate one mechanism by which putrescine (Put) functions in plant signaling under osmotic stress, Put and ABAcontents, and plasma membrane-NADPH oxidase (PM-NOX) activity were detected in wheat seedling leaves. Underosmotic stress, ABA and Put contents, PM-NOX activity, and PM-NOX-dependent O2.- production all increased. Theinhibitor tungstate (T) of ABA bio-synthesis reduced the increases in ABA and Put contents under osmotic stress. Theinhibitor D-arginine (D-Arg) of Put bio-synthesis didn’t reduce osmotic-induced increase of ABA, but it inhibited theincreases of PM-NOX activity and O2. - production, and the inhibitory effects were reversed by exogenous Put. Thesefindings suggested that ABA might regulate Put biosynthesis, and Put might regulate PM-NOX activity. Treatments withthree inhibitors imidazole (I), diphenylene iodonium (DPI) and pyridine (P) of PM-NOX reduced significantly not only O2. -production, but also the stress-induced increase of Put content, which indicated that O2. - production might regulate Putbiosynthesis. Treatments with EGTA (Ca2? chelator), La3? and verapamil (V) (Ca2? channel blockers) reduced significantly the stress-induced increase of Put content, which suggested that Ca2? might regulate Put biosynthesis. With thesefindings, it could be concluded that Put was involved in ABA signaling induced by osmotic stress via regulating PM-NOXactivity in wheat seedling leaves.

Effect of different polyamines on some physiological traits, growth, and development of basil (Ocimum basilicum L.) in salt stress under hydroponic culture conditions

As basil occurs in the arid and semi-arid regions, the drought and salinity decrease the vegetative growth andleaf area. This research was carried out in Pakdasht private greenhouse to evaluate the effect of putrescine,spermine, and spermidine on quality and quantity of basil under conditions of salt stress. This research wasdone as a factorial experiment in a completely randomized block design with three replications. The treatmentsincluded application of putrescine, spermine, and spermidine at four levels (0, 50, 100, and 150 mg/l), salinitystress at four levels (0, 50, 100, and 150 mM), and control treatment. The results showed that the interactioneffects between polyamines, salinity, and concentration on plant height, fresh/dry shoot weight, fresh/dryweight of root, fresh/dry leaf weight, leaf chlorophyll content, catalase, peroxidase and guaiacol peroxidaseantioxidant enzymes, the ratio of K/Na ratio, ion leakage, and proline were statistically significant at 1% level.Interaction and simultaneous exposure of 150 mg/l spermidine and low salinity had a positive effect on all thestudied plant traits. In addition, the results showed that the concentration of 150 mM sodium chloride solutionreduced the mentioned traits. However, spermidine improved this condition, and symptoms of stress anddamages were less observed in spermidine-treated plants. Therefore, it can be used to withstand the oxidativestress of plants.

The application of polyamines and self-incompatibility control substance on yield indices and qualitative traits of apple cv ‘Red Delicious’ / A aplicação de poliaminas e substância de controle de auto-incompatibilidade em índices de produção e características qualitativas da maçã 'Red Delicious'

Among the main problems of some temperate fruit species, such as the apple tree (Malus domestica), are the poor set of fruits and low production. Polyamines and Self-Incompatibility Control Substances (SICS), involving mineral nutrients such as manganese and boron, are the major chemical compounds used to reduce these problems. The aim of this study was to use popular polyamines putrescine (Put) at 0.1, 0.25 mM, spermine (Spm) and spermidine (Spd) both at 0.05, 0.25 mM and SICS at 1, 2 mg L-1, alone or with cotton coverage bags and control to show the effects of these chemical compounds on yield indices and qualitative traits of apple (Malus domestica) cv ‘Red Delicious’. Results showed that Spd (0.25 mM) and SICS (1 mg L-1) had higher effect on yield per weight and per fruit number, final fruit set and ISI, but Spd (0.25 mM) decreased final drop. Put (0.1 mM + ccb), Spd (0.25 mM) and SICS (2 mg L-1 + ccb) were the most suitable treatments in order to increase the qualitative characteristics.

Entre os principais problemas de algumas espécies frutíferas de clima temperado, como a macieira (Malus domestica), está o fraco conjunto de frutos e a baixa produção. As Poliaminas e Substancias de Controle de Auto-Incompatibilidade (self-incompatibility control substances-SICS) (envolvendo nutrientes minerais tais como manganês e boro) são os principais compostos químicos usados para reduzir esses problemas. O objetivo deste trabalho foi empregar a poliamina putrescina (Put) em 0,1, 0,25 mM, espermina (Spm) e espermidina (Spd) ambas em 0,05, 0,25 mM e SICS em 1,2 mg L-1, sozinhos ou com sacos cobertos de algodão, para demonstrar o efeito destes elementos químicos nos índices de produção e características qualitativas da maça (Malus domestica) ‘Red Delicious’. Resultados mostraram que a espermidina (0.25 mM) e SICS (1 mg L-1) tiveram um efeito maior na produção por peso e pelo número de frutos, o conjunto final de frutos e ISI, mas a espermidina (0.25 mM) caiu na produção final. Put (0.1 mM + sca), Spd (0.25 mM) e SICS (2 mg L-1 + sca) foram os tratamentos mais adequados para aumentar as características qualitativas.

A useful procedure for detection of polyamines in biological samples as a potential diagnostic tool in cancer diagnosis

Background: Polyamines present in human body are frequently considered as markers of occurrence of cancer. Therefore, the availability of simple and efficient method for determination of their level in body liquids and tissues is of some interest. Methods: Supported liquid membrane technology coupled with HPLC seems to be an appropriate technique to follow the level of polyamines in human blood and urine. Thus, the membranes of two different geometries: flat sheet and hollow fiber were studied as a mean for separation and enrichment of studied polyamines from urine and tissue samples in order to prepare samples to be analyzed by HPLC. Conclusions: Developed extraction systems offer an interesting alternative to traditional techniques such as: liquid-liquid or solid-phase extraction due to several features, which are: very high enrichment of polyamines without previous work-up, simple procedure of extraction and tiny volume of organic solvents used. This enables efficient determination of their levels in body liquids (AU)

Overexpression of NtPMT and HnH6H changed hyoscyamine-rich Atropa belladonna to scopolamine-rich varieties / 药学学报

Atropa belladonna L. is the commercial plant material for production of tropane alkaloids, including hyoscyamine and scopolamine. The wild-type Atropa belladonna is characterized by the hyoscyaminerich chemotype, in which the hyoscyamine content is much higher than the scopolamine content. It is the common goal for the pharmaceutical industry to increase the content of scopolamine in A. belladonna. Based on the T0 progeny of transgenic A. belladonna with NtPMT and HnH6H overexpression, T1 progeny of transgenic A. belladonna were obtained through self-pollination and used in a field trial. The 461 bp fragment of NtPMT and the 1 077 bp HnH6H were simultaneously expressed from T1 progeny of transgenic A. belladonna, but were not obtained from the wild-type A. belladonna. At the transcription level, the expression of NtPMT and HnH6H were detected in T1 progeny of transgenic A. belladonna, but were not detected in the wild-type plants. Further, the alkaloids were analyzed by HPLC. In the stems and leaves of T1 progeny of transgenic A. belladonna, hyoscyamine was not detected and scopolamine was detected at very high levels; in the stems and leaves of wild-type A. belladonna, hyoscyamine was detected at much higher levels. In the leaves of T1 progeny of transgenic A. belladonna, the content of scopolamine was 15-36 folds higher than that of wildtype leaves; in the stems of T1 progeny of transgenic A. belladonna, the scopolamine content was 37-108 folds higher than that of wild-type stems. In conclusion, overexpression of NtPMT and HnH6H greatly enhanced conversion of hyoscyamine into high-value scopolamine and improved the commercial value of A. belladonna.

A microdroplet cell culture based high frequency somatic embryogenesis system for pigeonpea, Cajanus cajan (L.) Millsp.

A protocol for high frequency production of somatic embryos was worked out in pigeonpea, Cajanus cajan (L.) Millsp. The protocol involved sequential employment of embryogenic callus cultures, low density cell suspension cultures and a novel microdroplet cell culture system. The microdroplet cell cultures involved culture of a single cell in 10 µl of Murashige and Skoog’s medium supplemented with phytohormones, growth factors and phospholipid precursors. By employing the microdroplet cell cultures, single cells in isolation were grown into cell clones which developed somatic embryos. Further, 2,4-dichlorophenoxyacetic acid, kinetin, polyethylene glycol, putrescine, spermine, spermidine, choline chloride, ethanolamine and LiCl were supplemented to the low density cell suspension cultures and microdroplet cell cultures to screen for their cell division and somatic embryogenesis activity. Incubation of callus or the inoculum employed for low density cell suspension cultures and microdroplet cell cultures with polyethylene glycol was found critical for induction of somatic embryogenesis. Somatic embryogenesis at a frequency of 1.19, 3.16 and 6.51 per 106 cells was achieved in the callus, low density cell suspension cultures and microdroplet cell cultures, respectively. Advantages of employing microdroplet cell cultures for high frequency production of somatic embryos and its application in genetic transformation protocols are discussed.

Exogenous application of putrescine at pre-anthesis enhances the thermotolerance of wheat (Triticum aestivum L.).

Antioxidant enzymes, besides being involved in various developmental processes, are known to be important for environmental stress tolerance in plants. In this study, the effect of treatment of 2.5 mM putrescine (Put), heat stress (HS -42°C for 2 h) and their combination on the expression and activity of antioxidant enzymes was studied at pre-anthesis in the leaves of two wheat (Triticum aestivum L.) cultivars — HDR77 (thermotolerant) and HD2329 (thermosusceptible). We observed that 2.5 mM Put before HS significantly enhanced the transcript levels of superoxide dismutase (SOD), catalase (CAT), cytoplasmic and peroxisomal ascorbate peroxidase (cAPX, pAPX) in both the cultivars. However, the activities of antioxidant enzymes (SOD, CAT, APX and GR), as well as accumulation of antioxidants (ascorbic acid and total thiol content) were higher in HDR77 than in HD2329 in response to the treatment 2.5 mM Put + HS. No significant change was observed in the proline accumulation in response to HS and combined treatment of 2.5 mM Put + HS. A decrease in the H2O2 accumulation, lipid peroxidation and increase in cell membrane stability (CMS) were observed in response to 2.5 mM Put + HS treatment, as compared to HS treatment alone in both the cultivars; HDR77 was, however, more responsive to 2.5 mM Put + HS treatment. Put (2.5 mM) treatment at pre-anthesis thus modulated the defense mechanism responsible for the thermotolerance capacity of wheat under the heat stress. Elicitors like Put, therefore, need to be further studied for temporarily manipulating the thermotolerance capacity of wheat grown under the field conditions in view of the impending global climate change.

Polyamine-mediated triterpenoid synthesis in suspension cells of Betula platyphylla induced by fungal elicitor / 中草药

Objective: To clarify whether polyamine-mediated triterpenoid synthesis in birch (Betula platyphylla) suspension cells induced by fungal elicitor. Methods: Fungal elicitor (40 μg/mL), putrescine (Put, 1 mmol/L), and D-arginine (D-Arg, 2 mmol/L) were added to the eight-day-old suspension cell culture, the content changes of triterpenoid and free polyamines were analyzed by chemical colorimetry and HPLC. The effect of polyamine on triterpenoid synthesis in B. platyphylla suspension cells induced by fungal elicitor was analyzed by pharmacology and restoration experiment. Results: After the treatment of fungal elicitor or Put, the contents and yields of free polyamines and triterpenoid were increased. Among of them, the triterpenoid content was the highest after 24 h treatment, the increasing rates were 68.54% and 30.34%, respectively. The triterpenoid content was increased by the cotreatment of fungal elicitor and Put, but the increasing degree of yield was lower than that by the treatment of fungal elicitor alone. Compared with the fungal elicitor alone, the cotreatment of fungal elicitor and D-Arg decreased the triterpenoid content by 40.57% in the highest degree of decreasing after 24 h treatment. In restoration experiment, with the treatment time prolonging, the effect of fungal elicitor, Put, or cotreatment of fungal elicitor and D-Arg on triterpenoid synthesis was decreasing to the control level finally. Conclusion: Polyamine could mediate the triterpenoid synthesis in cells of B. platyphylla induced by fungal elicitor.

Effect of putrescine on sucrose metabolism and triterpenoid accumulation in Betula platyphylla suspension cells / 中草药

Objective: To analyze the effect of exogenous putrescine on triterpenoid accumulation and sucrose metabolism. Methods: Putrescines (0.1, 1, and 5 mmol/L) were added to the eight-day-old suspension cell culture, and the content changes of sucrose, fructose, glucose, and triterpenoid, the activity of sucrose phosphate synthase (SPS) and sucrose synthase (SS) were analyzed by colorimetry. Results: Putrescine increased the content of sucrose in cells but decreased the conent in culture medium. Among them, the content of sucrose was most enhanced after putrescine induction for 6 h; The increasing rate was 169.41%. However, the contents of fructose and glucose were only increased in 6 h under the putrescine treatment, the other treatments decreased the contents of fructose and glucose. In addition to 5 mmol/L putrescine treatment, putrescine enhanced the activities of SPS and SS. The content of triterpenoid in suspension cells was increased in 12 h after 5-40 g/L sucrose induction, and the content of triterpenoid was most induced by 20 g/L sucrose, the increasing rate was 52.16%. In addition to increasing 27.37% on triterpenoid content in cells treated by 1 mmol/L putrescine and 5 g/L sucrose, the treatment of 1 mmol/L putrescine and other sucrose concentration decreases the accumulation of triterpenoid. Conclusion: Putrescine could increase the sucrose content and triterpenoid accumulation in suspension cell culture, and we preliminarily inferred that the induction of sucrose by putrescine could participate in the accumulation of triterpenoid in birch cells.

Contenido de poiiaminas libres en palmas afectaas por pudricion del cogollo enn las zonas central y occidental de Cloombia / Free olyamine coontent on oil palms aected by bud rot in the Colombiian central and western palm regions

La pudrición del cogollo (PC) es la principal enfermedad de la palma en Colombia. En las zonas palmeras Central (ZC) y Oriental (ZOR), las palmas enfermas pueden recuperarse naturalmente. En la Zona Occidental (ZOCC) el proceso de recuperación no es evidente. La recuperación de palmas está ligada a gran actividad meristemática que podría involucrar la acción de metabolitos como las poliaminas (PA). Este trabajo muestra la relación entre el contenido de poliaminas en el meristemo y la capacidad de recuperación de palmas con PC, en dos zonas agroclimáticas diferentes. Poliaminas extraídas del meristemo de palmas en ZC y ZOCC, fueron analizadas por HPLC. En ZC, donde existe recuperación espontánea, los niveles más altos de PA se presentan en palmas sanas y en recuperación y a medida que avanza la enfermedad la concentración desciende hasta un mínimo en el estado de PC inicial. Luego la concentración de PA aumenta hasta el estado de Buena Recuperación donde los valores de poliaminas son más altos que los de palmas sanas. En la ZOCC , el contenido de PA aumenta con la enfermedad llegando al máximo en plantas sin recuperación y el mínimo en plantas sanas. Las diferencias entre zonas pueden explicarse por los diferentes roles de las poliaminas en plantas. En la ZC la cantidad elevada de PA en palmas sanas o en recuperación funcionaría en la inducción de actividad meristemática, para la recuperación espontánea. En la ZOCC el aumento en el contenido de PA con la enfermedad puede estar relacionado con la producción de especies reactivas de oxigeno para defensa secundaria contra patógenos. A diferencia de lo observado en ZC , las plantas en ZOCC no pueden producir estructuras sanas que no sean re infectadas, por lo tanto los elevados contenidos de PA no están relacionados con la promoción de la actividad meristemática.

Bud Rot complex (BR) is the major disease of oil palm in Colombia . In the Central (ZC) and Eastern (ZE) oil palm regions, palms affected by BR are able to naturally recover. In the Western Region (ZW) the recovery process is not evident. Recovery of the palms is linked to high meristem activity, which could involve the promoting action of plant growth regulators such as polyamines (PA). This study shows the relationship between polyamine content and the capacity of palms to recover from BR in two regions with different agroclimatic conditions. Polyamines extracted from palms planted on ZC and ZW were analyzed by HPLC. On ZC where spontaneous recovery is present, the highest values were measured on healthy and recovery palms and with the progression of the disease, PA concentration decreased reaching a minimum point in the initial BR stage. From this point, PA concentration gradually increased until the Good Recovery stage in which PA values where higher than those found on healthy palms. In ZW , PA content increased with the disease, reaching the highest value in the affected palms without recovery, with the lowest values measured on healthy palms. The differences between regions might be related to the different roles polyamines play on plants. In ZC the increased amount of PA in healthy palms or in palms under recovery could have a major role in meristem activity induction, required for the spontaneous recovery. In the ZW, the increased of PA content with the disease could be related to the production of reactive oxygen species as a plant secondary defense mechanism due to the impossibility for the plants to, through the increment on meristem activity as the observed in the Central region, produce healthy structures which are not re-infected.

Polyamine patterns in haploid and diploid tobacco tissues and in vitro cultures

The aim of this work was to determine PAs levels in pith tissues and callus cultures from haploid and diploid tobacco plants, explanted from the apical and basal regions of the stem. These explants were cultured in an RM-64 medium supplied with IAA and kinetin, under light or in the dark, during successive subcultures. PAs levels followed a basipetal decrease in diploid and an increase in haploid, pith tissues. A similar pattern of total PAs (free + conjugated) was observed for the callus of diploid and haploid plants maintained in the light, and for the haploid callus in the dark, whereas the diploid callus in the dark showed a constant increase in total PAs levels until the end of culture. The PA increase in the diploid callus in the dark was related to free Put levels increase. The ploidy status of the plants could express different PA gradients together with the plant pith and in vitro callus cultures.

O objetivo deste trabalho foi determinar os níveis de PAs em tecidos de medula e cultura de calos de plantas haplóides e diplóides de tabaco, obtidas da região apical e basal do caule. Estes explantes foram cultivados em meio RM-64 suplementado com AIA e cinetina, na luz e no escuro, durante vários subcultivos. Nos tecidos medulares, os níveis de PAs apresentam um decréscimo basípeto em diplóides e um aumento em haplóides.Um padrão similar nos níveis de PAs totais (livres+ conjugadas) foi observado em calos haplóides e diplóides mantidos na luz, e haplóides no escuro, enquanto os diplóides cultivados no escuro mostraram um aumento constante até o final do cultivo. O aumento no conteúdo de PAs nos calos diplóides no escuro, foi devido ao aumento do conteúdo de Put livre. Foi observado que a ploidia da planta pode expressar diferentes gradientes de PA ao longo do tecido medular e nas culturas de calos in vitro.

Reguladores vegetais e teores endógenos de poliaminas durante o desenvolvimento de taro cultivado in vitro / Plant growth regulators in polyamines endogenous levels during the development of taro cultivated in vitro

Neste trabalho foi investigada a assepsia para obtenção de explantes oriundos de tubérculos e a ação das poliaminas espermidina e espermina exógenas associadas aos reguladores vegetais AIA e BA no desenvolvimento, na tuberização in vitro e nos níveis endógenos de putrescina (Put), espermidina (Spd) e espermina (Spm) de taro (Colocasia esculenta). Plantas crescidas em meio contendo espermidina e espermina mostraram tuberização e a associação dessas poliaminas com AIA e BA induziu aumento do número de brotações. Para o estímulo da rizogênese, não foi necessário o uso de reguladores vegetais. Altos teores de putrescina foram encontrados durante a emissão de brotações, enquanto que altos teores de espermidina foram observados durante a formação de rizomas in vitro.

The present research investigated the asepsis for attainment of explants deriving of tubers and the polyamines espermidine and espermine exogenous effects associated with the plant growth regulators NAA and BA on the development and tuberization in vitro and the endogenous levels of putrescine (Put), spermidine (Spd) and spermine (Spm) of taro (Colocasia esculenta). Plants grown in the medium with spermidine and spermine showed tuberization and the association of these polyamines with NAA and BA increases number of shoots. Plant growth regulators were not necessary for root initiation. High levels of endogenous Put were found during the shoot emission, while high levels Spd were observed during in vitro root formation.

Papel de las poliaminas en la alimentación: Importancia de las poliaminas en la alimentación infantil

Durante la década de los 90 del siglo pasado comenzaron los primeros estudios que señalaban a las poliaminas como importantes factores de crecimiento de la leche materna. Sin embargo, todavía se desconoce mucho sobre el papel que desempeñan en la alimentación infantil y cual sería la ingesta recomendada para este grupo poblacional. En los últimos años va siendo cada vez mayor la atención que muestra la comunidad científica internacional hacia las poliaminas, debido no sólo al importante papel que desempeñan en el metabolismo celular, sino por su posible participación en diversas patologías y durante el desarrollo del organismo. Sería recomendable, teniendo en cuenta que el contenido en poliaminas de las fórmulas infantiles es unas 10 veces menor al de la leche materna, profundizar más en este campo, con el fin de garantizar una correcta alimentación durante la etapa de lactancia.

Role of polyamines in diet. Importance of polyamines in infant nutrition. The first studies indicating polyamines as important growth factors in breast milk began during the nineties of last century. Nevertheless, it is still not well known the role they play in infant nutrition or what the recommended intake would be for this population group. In recent years, there has been increased attention of the international scientific community towards polyamines, not only due to the important role they play in the cellular metabolism, but also to their possible implication in some diseases and during the development of the human organism. Bearing in mind that the content in polyamines of the infant formula is around tenfold less than in breast milk, it would be recommended to gain insight into this theme in order to guarantee correct nutrition during lactation.

Effects of Polyamines on Contractility of Guinea-Pig Gastric Smooth Muscle

This study was designed to investigate the effects of polyamines on mechanical contraction and voltage-dependent calcium current (VDCC) of guinea-pig gastric smooth muscle. Mechanical contraction and calcium channel current (I(Ba)) were recorded by isometric tension recording and whole-cell patch clamp technique. Spermine, spermidine and putrescine inhibited spontaneous contraction of the gastric smooth muscle in a concentration-dependent manner. Spermine (2 mM) reduced high K+ (50 mM)-induced contraction to 16+/-6.4% of the control (n=9), and significantly inhibited I(Ba) in a reversible manner (p<0.05; IC50=0.8 mM). Pre- and post-treatment of tissue with spermine (2-5 mM, n=10) also inhibited acetylcholine (10 micrometer)-induced phasic contraction to 5+/-6.4% of the control. Inhibitory effect of spermine on I(Ba) was observed at a wide range of test potentials of current/voltage (I/V) relationship (p<0.05), and steady-state activation of I(Ba) was shifted to the right by spermine (p<0.05). Spermidine and putrescine (1 mM each) also inhibited I(Ba) to 51+/-5.7% and 81+/-5.3% of the control, respectively. And putrescine (1 mM) inhibited I(Ba) at whole tested potentials (p<0.05) without significant change of kinetics (p<0.05). Finally, 5 mM putrescine also inhibited high K+ -induced contraction to 53+/-7.1% of the control (n=4). These findings suggest that polyamines inhibit contractions of guinea-pig gastric smooth muscle via inhibition of VDCC.

Effect of Melatonin Administration on the Immobilization Stress-induced Polyamine Responses in Brain and Gastrointestinal Tract / 대한정신약물학회지

OBJECTIVE: The present study was designed to identify the acute and chronic immobilization stress-induced polyamine (putrescine) responses and their modulation by administration of melatonin in brain regions (frontal cortex and hippocampus) and gastrointestinal tract regions (GIT, gastric mucosa and duodenal mucosa). METHOD: For immobilization stress (3 or 14 days), rats (250-300 g, male Sprague-Dawley rats) were placed in restrainers once daily, for 3 h. Melatonin (10 mg/kg, i.p.) was administered once daily immediately after stress. Rats were sacrificed 2 h after the final application of stress for the measurement of putrescine levels. RESULTS: The putrescine levels of frontal cortex, hippocampus, gastric mucosa and duodenal mucosa were significantly increased by acute stress (p<0.05, p<0.05, p<0.0005 and p<0.01, respectively). The putrescine levels of frontal cortex and duodenal mucosa were significantly increased by chronic stress (p<0.05, respectively). In chronic stress group, animals showed adaptation tendency. The changes of putrescine level in gastric and duodenal mucosa induced by chronic stress were significantly lower than those by acute stress (p<0.05, respectively). The putrescine responses to acute stress in frontal cortex, hippocampus, gastric mucosa and duodenal mucosa were attenuated by administration of melatonin (p<0.01, p<0.05, p<0.05 and p<0.05, respectively). The putrescine response to chronic stress in frontal cortex was attenuated by melatonin administration (p<0.05, respectively). CONCLUSION: The results suggested that putrescine may play a role in stress response of brain regions (frontal cortex and hippocampus) and GIT regions (gastric and duodenal mucosa). Melatonin can inhibit the stress-induced putrescine responses in the brain and GIT.

Effects of dexamethasone and DHEA on the changes of glutamate and polyamine uptake in rat astrocytes by lipopolysaccharide and antimycin A

Interactions among dexamethasone, dehydroepiandrosterone (DHEA), lipopolysaccharide (LPS), and antimycin A on the glutamate uptake and the polyamine uptake were investigated in primary cultures of rat cerebral cortical astrocytes to examine the effects of dexamethasone and DHEA on the regulatory role of astrocytes in conditions of increased extracellular concentrations of glutamate or polyamines. 1. (3H)Glutamate uptake: LPS and antimycin A decreased Vmax, but both drugs had little effect on Km. Dexamethasone also decreased basal Vmax without any significant effect on Km. And dexamethasone further decreased the antimycin A-induced decrease of Vmax. DHEA did not affect the kinetics of basal glutamate uptake and the change by LPS or antimycin A. 2. (14C)Putrescine uptake: LPS increased Vmax, and antimycin A decreased Vmax. They showed little effect on Km. Dexamethasone decreased Vmax of basal uptake and further decreased the antimycin A-induced decrease of Vmax, and also decreased Vmax to less than control in LPS-treated astrocytes. DHEA did not affect Km and the change of Vmax by LPS or antimycin A. 3. (14C)Spermine uptake: Antimycin A decreased Vmax, and LPS might increase Vmax. Km was little affected by the drugs. Dexamethasone decreased basal Vmax and might further decrease the antimycin A-induced decrease of Vmax. And dexamethasone also decreased Vmax to less than control in LPS-treated astrocytes. DHEA might increase basal Vmax and Vmax of LPS-treated astrocytes. 4. Vmax of glutamate uptake by astrocytes was increased by putrescine (1000 muM & 2000 muM) and spermidine (200 muM, 500 muM & 2000 muM). Spermine, 200 muM (and 100 muM), also increased Vmax, but a higher dose of 2000 muM decreased Vmax. Km of glutamate uptake was not significantly changed by these polyamines, except that higher doses of spermine showed tendency to decrease Km of glutamate uptake. In astrocytes, dexamethasone inhibited the glutamate uptake and the polyamine uptake in normal or hypoxic conditions, and the polyamine uptake might be stimulated by LPS and DHEA. Polyamines could aid astrocytes to uptake glutamate.

Association of dexamethasone-induced apoptosis of G|1-arrest of human leukemic CEM cells with polyamine deficit

The effects of DFMO or/and putrescine on the dexamethasone-induced apoptosis of CEM cells were studied to investigate the role of polyamines in anti-leukemic glucocorticoid action. Dexamethasone-induced apoptosis was preceded by significant decreases of cellular polyamine contents and putrescine uptake activity. But DFMO produced decreases of putrescine and spermidine contents and marked increase of putrescine uptake activity, but did not induce apoptosis. However, dexamethasone and DFMO, respectively, induced G|1-arrest in cell cycle and hypophosphorylation of pRb, resulting in the increase of G|1 to S ratio and decrease of CEM cell count. DFMO enhanced the dexamethasone-induced apoptosis and G|1-arrest. On the other hand, putrescine little affected the apoptotic and G|1-arresting activities of dexamethasone, but almost suppress the effects of DFMO and also the DFMO-dependent enhancement of dexamethasone effects. These results suggested that the dexamethasone-induced apoptosis to be associated with pRb hypophosphorylation and G|1-arrest in CEM cells might be ascribed to the concomitant decreases of cellular polyamine contents and putrescine uptake activity.

Control of ornithine decarboxylase activity in jute seeds by antizyme.

The control of ornithine decarboxylase activity by antizyme was studied during early germination of jute seeds (Corchorus olitorius). When 2 mM of putrescine and spermidine were applied to the germinating medium, the enzyme activity was markedly inhibited (1.7-fold) during 16 h imbibition. This inhibition could be attributed to the formation of an inhibitory protein termed antizyme. The antizyme was partially purified from jute and barley seedlings. The activity of jute ornithine decarboxylase antizyme was weaker than that of barley.

Arginine decarboxylase is a component activity of the multifunctional.

A homogenous preparation of putrescine synthase, the versatile multifunctional enzyme involved in agmatine→putrescine conversion in Cucumis sativus was found to catalyze enzymatic decarboxylation of arginine also. Similarly, the purified arginine decarboxylase mediated the component as well as the complete set of coupled reactions harboured by putrescine synthase. Both the enzyme preparations exhibited identical electrophoretic and chromatographic behaviour and were immunologically indistinguishable. All the enzymic activities are stabilized concurrently by feeding arginine to the intact seedlings. Therefore, it is concluded that the multifunctional putrescine synthase in Cucumis sativus seedlings also harbours arginine decarboxylase activity unlike its counterpart in Lathyrus sativus.

Purification and characterization of putrescine synthase from cucumber seedlings. A multifunctional enzyme involved in putrescine biosynthesis.

The multifunctional enzyme, putrescine synthase has been purified from Cucumis sativus and characterized. This enzyme harbours agmatine iminohydrolase, ornithine transcarbamylase, putrescine transcarbamylase and carbamate kinase activities, whose concerted action results in agmatine → putrescine conversion. The enzyme resolved into two aggregation forms, enzyme aggregated and enzyme monomer upon electrophoresis at pH 8·3. Evidence has been provided by two-dimensional gel electrophoresis that both enzyme aggregated and enzyme monomer comprise of identical polypeptide chains. Under non-reducing conditions on sodium dodecyl sulphate-polyacrylamide gel electrophoresis, the protein moves as a single 150 KDa polypeptide; however, in the presence of 2-mercaptoethanol on sodium dodecyl sulphate-polyacrylamide gel elec trophoresis, it migrates as 3 polypeptides of molecular weight 48,000, 44,000 and 15,000. The enzyme undergoes age-dependent in vivo proteolytic degradation from a 66 KDa polypeptide (primary translational product), through 48 KDa polypeptide to 44 KDa species and finally to small molecular weight peptides.