mM Of Putrescine Research Articles

Chitosan–putrescine nanoparticle coating attenuates postharvest decay and maintains ROS scavenging system activity of strawberry cv. ‘Camarosa’ during cold storage

ABSTRACT The application of some natural compounds and cold storage can reduce postharvest loss and improve fruit quality and storability, which increase the fruit marketing period and exportation to distant markets. This study investigated the effectiveness of using coatings based on natural polymers to prolong the shelf life of fruits and protect their tissues from damage. Specifically, the researchers examined the impact of putrescine (PUT), chitosan (CTS) and chitosan–putrescine nano-composites (CTS-PUT NPs) on preserving the quality and reducing decay in strawberry. Strawberries were treated with either 1 mM or 2 mM of PUT, 0.1% CTS, 0.1% CTS-PUT NPs or distilled water at a temperature of 20°C for 5 min and then stored at 4°C for 12 days. At the end of the storage period, the lowest decay percentage was related to the treatments of CTS-PUT NPs and CTS, and the highest was observed in the control. The results showed that all coating treatments effectively prevented the excessive loss of ascorbic acid, fruit firmness, total soluble solids (TSS), and acidity (TA) compared to control at the end of the storage period. Additionally, strawberries treated with CTS-PUT NPs and CTS demonstrated the highest levels of total anthocyanin and total flavonoid. Antioxidant enzyme activities containing CAT and SOD were preserved at higher levels in treated strawberries than in the control during cold storage. These results confirm that the application of CTS and CTS-PUT NPs can effectively preserve fruit quality and prolong the longevity of strawberries during cold storage by enhancing their antioxidant capacity and scavenging free radicals.

Exogenous citric acid, salicylic acid, and putrescine treatments preserve the postharvest quality and physicochemical properties of broccoli (Brassica oleracea L. var. italica) during cold storage

AbstractTo extend the postharvest storage life of broccoli samples (Brassica oleracea L. var. italica), an exogenous application of citric acid (CA), salicylic acid (SA), and putrescine (PUT) was tested in multiple combinations (0.5 and 1 mM) at 4 ± 0.5°C and 90 ± 5% relative humidity (RH) for 21 days (d). The weight loss (WL), respiration rate (RR), total soluble solids (TSS), pH, color (L*, a*, b*, chroma, and hue angle), proximate and mineral contents, phenolic and flavonoid contents, and other biochemical properties of the treated and untreated broccoli samples were evaluated throughout the storage duration. The lowest WL was observed when exposed to 0.5 mM of PUT. 1 mM CA and PUT treatments were affected by RR, depending on storage conditions. The lowest TSS content was observed in broccoli samples treated with 0.5 mM CA among all treatments. The chroma value of the samples was preserved by the 0.5 mM SA treatment. The most abundant element in broccoli samples was potassium in the control application, followed by a 1 mM SA treatment. In addition, the protein content was the highest in the 1 mM PUT treatment. The highest vitamin C was determined in the 1 mM CA treatment, and the most abundant vanillic acid was found in broccoli exposed to the 0.5 mM and treatment. Glucose content was determined at the lowest level in the 0.5 mM SA treatment, while higher increases occurred in other treatments. In terms of these findings, 1 mM CA, 1 mM SA, and 1 mM PUT delay WL, RR, and color degradation and prolong the storage life of broccoli samples stored at 4 ± 0.5°C. It was concluded that the biochemical content, fresh weight, and green color of broccoli samples throughout postharvest and storage can be maintained longer by exogenous application of these natural compounds. Therefore, we recommend 1 mM PUT and 1 mM CA treatments to maintain the quality of broccoli by minimizing losses in morphological properties, mineral, and biochemical compositions during postharvest storage.

Colorimetric Paper Sensor for Food Spoilage Based on Biogenic Amine Monitoring.

Biogenic amines (BAs), nitrogenous molecules usually present in different foods, can be considered an indicator of freshness and food quality since their amount increases during food spoilage. Their detection, possibly in real time via the use of smart packaging, is therefore of crucial importance to ensure food safety and to fulfill consumers' demand. To this end, colorimetric sensors are considered one of the most feasible solutions. Here, we report a user-friendly colorimetric sensing paper able to detect BAs via the naked eye. The sensing molecule is the aglycone genipin, a natural cross-linking agent extracted from gardenia fruit, able to bind BAs producing water-soluble blue pigments. The paper sensor was applied to chicken meat quality monitoring and a quantitative analysis was performed with image acquisition via a smartphone camera, achieving a limit of detection equivalent to 0.1 mM of putrescine. The suitability of the BA sensing paper was assessed by integrating the sensor into smart packaging and analyzing commercial chicken meat samples stored at different temperatures; the results of the sensor paralleled the "best before date" indicated on the label, confirming the potential applicability of the sensor as a smart label.

Harvest time explains substantially more variance in yield, essential oil and quality performances of Salvia officinalis than irrigation and putrescine application.

Elicitors, irrigation regimes and harvest times influence the content, yield and compound of the essential oil (EO) in Salvia officinalis (sage), through changes in biomass dynamics and biosynthetic pathways. A two-year field experiment was conducted to determine if foliar application of putrescine under optimum and deficit stress conditions would favorably affect EO yield, content and profile of sage harvested in spring and summer. The response of dry weight, EO yield and content, myrcene and borneol concentrations to irrigation regime and putrescine concentration can be expressed by a quadratic model. The maximum dry weight (182.63gm-2) and EO yield (1.68gm-2) were predicted under irrigation regimes of 9.06% and 27.75% available soil water depletion (ASWD), respectively.The highest EO content (1.05%) was predicted under 3.04mM of putrescine. Based on results obtained from GC/MS analyses, 25 compounds (mostly monoterpenes) were identified in the EO of sage. Among EO compounds, α-thujone (54.08%), 1, 8-cineole (17.87%), pinocarvone (14.30%), β-thujone (7.97%) and camphor (8.76%) in turn were the most abundant. The concentration of myrcene was higher in spring than summer under the irrigation regimes of 60% and 80% ASWD. The myrcene concentration reached its maximum (4.53%) under the irrigation regime of 86.5% ASWD. The irrigation regimes of 48.03% and 45.6% ASWD caused the highest borneol concentrations of 1.47% and 1.41% by application of 1.5mM and 2.25mM putrescine, respectively. All treatments tested on sage, particularly harvest time, can play an important role in the improvement of EO quality and quantity. Averaged over both years, the irrigation regime of nearly 30% ASWD resulted in the highest EO yield harvested with greater quantity and better quality in summer. The EO content and quality changed slightly with the application of putrescine, without significant effect on yield.

Role of Post-harvest Treatment of Polyamines on Physico-physiological Qualities of Papaya (Carica papaya L.) Fruits Var. Red Lady during Ambient Storage

Polyamines are the natural compound, act as anti-senescent agents, reduce rate of respiration, delay ethylene production, retard colour change, maintain fruit firmness. Show that plays a pivotal role in postharvest life of fruits and vegetables. The objective of this study was to investigate the effect of post-harvest application of polyamines in different concentration on physico-physiological quality parameters of papaya fruits during ambient storage (33-36oC). Papaya fruits are treated with different concentration of polyamines i.e., T2-0.50mM Spermine, T3- 1.0mM Spermine,T4- 1.5mM Spermine,T5- 0.50 mMSpermidine, T6- 1 mM Spermidine,T7- 1.5mM Spermidine,T8- 2 mM Putrescine,T9- 3 mM Putrescine,T10- 4 mM Putrescine and T1-Control. Among the treatments, papaya fruits treated with 4 mM of Putrescine (T10) recorded significantly minimum physiological loss in weight, respiration rate and colourvalues (L*, a*, b*) of peel and pulp, fruit disease index and maximum firmness, shelf life compared to control (T1). Hence it is confirmed from the study that Putrescine at 4mM (T10) was found to be effective in delaying the physico-chemical and physiological process of papaya fruit cv. Red Lady.

Polyamines and ethylene action blocker (STS) effectively augment longevity and postharvest attributes in isolated flowers of Digitalis purpurea L.

The present investigation focused on the study of the exogenous inclusion of anti-senescence biogenic polyamines (putrescine, spermidine and spermine) and ethylene antagonist silver thiosulphate on flower longevity and postharvest performance in excised flowers of Digitalis purpurea L. At one day before anthesis stage, isolated buds of Digitalis purpurea were transported to the laboratory in distilled water. The samples were divided into five sets with one set of flower buds (i.e., control) held in distilled water. The remaining four sets were respectively supplied with 0.5, 1 and 1.5 mM of putrescine (PUT), 0.1, 0.2 and 0.3 mM of spermidine (SPD), 0.2, 0.4 and 0.6 mM of spermine (SPM), 0.1, 0.2 and 0.3 mM of silver thiosulphate (STS). The inclusion of polyamines and STS in holding solutions enhanced the flower longevity of D. purpurea significantly compared to the control. The results indicated that the flower longevity of 14 days was recorded in 0.4 mM of spermine, followed by 13 days in 1 mM PUT, 12.5 days in 0.2 mM SPD and 12 days in 0.2 mM STS. This enhanced flower longevity corroborated with the higher values of soluble proteins, total sugars, floral diameter and membrane stability index. The improved flower longevity was also found to be positively associated with increased activities of various antioxidant enzymes viz., superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) and reduced activity of lipoxygenase (LOX). The flowers supplemented with different treatments retained a lower phenolic content than the control. This research concluded that polyamines and STS have a profound impact on the flower longevity of Digitalis flowers. SPM was found to be a more potential polyamine in augmenting the postharvest performance in isolated flowers of D. purpurea.

Withdrawn: Effects of water‐deficit stress and putrescine on performances, photosynthetic gas exchange, and chlorophyll fluorescence parameters of Salvia officinalis in two cutting times

A 2‐year (2017–2018) field experiment was performed to specify if the foliar application of putrescine (PUT) under optimum and water‐deficit stress (WDS) conditions would favorably affect leaf gas exchange, greenness, chlorophyll fluorescence parameters, pigments, sodium (Na), potassium (K), as well as yield and content of the essential oil (EO) relationships in Salvia officinalis L. (sage) in spring (cutting 1) and summer (cutting 2). Based on the results analysis of variance, the effects of WDS, PUT, and cutting time were significant for the dry weight, leaf area index (LAI), EO content, EO yield, chlorophyll (Chl) t, carotenoid, Na, and K of sage. According to regression results, the response of EO content, EO yield, non‐photochemical quenching (NPQ), spad, Chl a, Chl t, K, and K/Na to WDS can be expressed by a quadratic model, indicating that they would attain their maximum in 75.5%, 34.86%, 38.33%, 84.13% 60%, 70%, 50.40%, and 40.28% available soil water depletion (ASWD), respectively. The response of dry weight, LAI, EO content, EO yield, Fv/Fm, spad, ΦpsII, Chl a, Chl b, Chl t, carotenoid, K, and K/Na to PUT can be expressed by a quadratic model, showing that they would attain their most under 0.98, 1.14, 1.34, 1.16, 1.27, 1.18, 1.17, 1.25, 1.17, 1.27, 1.31, 1.21, and 1.19 mM of PUT, respectively. These findings suggest that, probably, the functions and structures of the photosynthetic system were further enhanced with PUT, thereby they can be promoting primary electron transfer in PSII. Also, stomatal and photosynthetic activity improved with increasing K levels with PUT.

Improvement of putrescine production through the arginine decarboxylase pathway in Escherichia coli K-12

In the bio-based polymer industry, putrescine is in the spotlight for use as a material. We constructed strains of Escherichia coli to assess its putrescine production capabilities through the arginine decarboxylase pathway in batch fermentation. N-Acetylglutamate (ArgA) synthase is subjected to feedback inhibition by arginine. Therefore, the 19th amino acid residue, Tyr, of argA was substituted with Cys to desensitize the feedback inhibition of arginine, resulting in improved putrescine production. The inefficient initiation codon GTG of argA was substituted with the effective ATG codon, but its replacement did not affect putrescine production. The essential genes for the putrescine production pathway, speA and speB, were cloned into the same plasmid with argAATG Y19C to form an operon. These genes were introduced under different promoters; lacIp, lacIqp, lacIq1p, and T5p. Among these, the T5 promoter demonstrated the best putrescine production. In addition, disruption of the puuA gene encoding enzyme of the first step of putrescine degradation pathway increased the putrescine production. Of note, putrescine production was not affected by the disruption of patA, which encodes putrescine aminotransferase, the initial enzyme of another putrescine utilization pathway. We also report that the strain KT160, which has a genomic mutation of YifEQ100TAG, had the greatest putrescine production. At 48 h of batch fermentation, strain KT160 grown in terrific broth with 0.01 mM IPTG produced 19.8 mM of putrescine.

Effects of putrescine application in culture medium in improving chamomile (Chamomilla recutita (L.) Rauschert.) tolerance to osmotic stress under in vitro conditions

In order to assess the effect of osmotic stress induced by mannitol and putrescine under in vitro conditions on some growth parameters of chamomile (Chamomilla recutita (L.) Rauschert.), treatments were arranged and compared for the main effect of osmotic stress induced by mannitol in four levels (0, 2, 4, and 6 g/l), and the interaction effect of osmotic stress*putrescine (0, 0.5, and 1 mM). Osmotic stress, especially induced by 4 and 6 g/l of mannitol, were found to significantly reduce shoot height, root length, the number of shoot and root per plant, the fresh weight of shoot, and the fresh weight of root. At 0.5 mM of putrescine added fresh weight to root, carotenoid, chlorophyll a, and chlorophyll b was increased, compared to plants grown on medium with 0 and 1 mM of putrescine. Plants grown on medium with 0.5 and 1 mM of putrescine had an increased level of flavonoid, phenolic acid, and proline under four levels of mannitol. 0.5 mM of putrescine significantly improved plant biomass and essential oil content in plants grown on medium containing 0 and 2 g/l of mannitol. The results showed that the use of putrescine could improve chamomile tolerance to osmotic stress.

Estresse térmico no acúmulo de prolina livre de plântulas de guandu oriundas de sementes tratadas com poliaminas

It was studied the effects of seed treatment with polyamines of pigeonpea for proline content of seedling in order to verify that the application of these polyamines attenuates temperature stress on germination and early seedling growth, and see if exogenous putrescine and spermidine induce the accumulation of proline, this amino acid may be biochemical and physiological indicator in seedlings that are under suboptimal temperatures and supraoptmail. The seeds of pigeonpea cv. BRS Mandarin and cv. Caqui, treated with a solution of 0.5 mM of putrescine and spermidine, were subjected to suboptimal temperature (20oC, 18oC, 16oC and 14oC) and supraoptimal (36oC, 38oC, 40oC and 44oC) for 24 hours and 48 hours. After these periods, were subjected to 25°C until day 10, when the percentage of seed germination were observed, the proline content of vegetative parts and the dry mass of the seedlings. A completely randomized design in a factorial arrangement was used 3x4x2+3 (solutions with polyamines, temperature stress by cooling/heating, time of exposure to stress, plus additional factors em25oC with 0.0 mM and 0.5mM of Put and Spd), with four replicates of 25 seeds. The results were submitted to analysis of variance and means were compared by Tukey test at 5% probability, separately for each cultivar. Both exogenous polyamines attenuate the effects of cooling and heating, contributing to the growth of germinated seeds. Also, putrescine and spermidine exogenous mitigated the adverse effects by inducing proline accumulation, which leads to osmotic adjustment temperatures, although this physiological response has not minimized the negative effects of temperature stress on seedling growth of pigeonpea. Proline can be considered biochemical and physiological indicator in seedlings of both cultivars of pigeonpea treated with polyamines under temperature stress.

Polyamines modulate nitrate reductase activity in wheat leaves: involvement of nitric oxide

In the present work, the effect of polyamines (PAs) on nitrate reductase (NR) activity was studied in wheat leaves exposed to exogenously added PAs while assessing the nitric oxide (NO) involvement in the regulation of the enzyme activity. A biphasic response was observed along the time of treatment using 0.1 mM of putrescine (Put), spermidine (Spd) or spermine (Spm). At 3 h, Spd and Spm significantly reduced NR activity by 29 or 35%, respectively, whereas at 6 h, the activity of the enzyme decreased by an average of 25%. At 21 h, Put increased NR activity by 63%, while Spd and Spm elevated the enzyme activity by 114%. NR activity, that was reduced by 0.1 mM Spm at 3 and 6 h, returned almost to control values when c-PTIO (an NO scavenger) was used, confirming that NO was involved in the inhibition of NR activity. Nitric oxide was also mediating the PA-increase of the enzyme activity at longer incubation times, evidenced when the raise in NR activity produced by 0.1 mM Spm at the longest incubation time returned to the value of the control in the presence of cPTIO. Neither the protein expression nor the nitrate content were modified by PAs treatments. The involvement of PAs and NO in the regulation of NR activity is discussed.

Putrescine production by engineered Corynebacterium glutamicum

Here, we report the engineering of the industrially relevant Corynebacterium glutamicum for putrescine production. C. glutamicum grew well in the presence of up to 500 mM of putrescine. A reduction of the growth rate by 34% and of biomass formation by 39% was observed at 750 mM of putrescine. C. glutamicum was enabled to produce putrescine by heterologous expression of genes encoding enzymes of the arginine- and ornithine decarboxylase pathways from Escherichia coli. The results showed that the putrescine yield by recombinant C. glutamicum strains provided with the arginine-decarboxylase pathway was 40 times lower than the yield by strains provided with the ornithine decarboxylase pathway. The highest production efficiency was reached by overexpression of speC, encoding the ornithine decarboxylase from E. coli, in combination with chromosomal deletion of genes encoding the arginine repressor ArgR and the ornithine carbamoyltransferase ArgF. In shake-flask batch cultures this strain produced putrescine up to 6 g/L with a space time yield of 0.1 g/L/h. The overall product yield was about 24 mol% (0.12 g/g of glucose).

Spermine and putrescine enhance oxidative stress tolerance in maize leaves

The protective effects of spermine (SPM) and putrescine (PUT) against paraquat (PQ), a herbicide in agriculture and oxidative stress inducer, were investigated in the leaves of maize. Maize leaves were pretreated to SPM and PUT at concentrations of 0.2 and 1 mM and treated with PQ afterwards. Pretreatment with 1 mM of SPM and PUT significantly prevented the losses in chlorophyll and carotenoid levels induced by PQ. Ascorbic acid content in the leaves pretreated with both polyamines was found to be higher than those of the leaves pretreated with water. Also, pretreatment with SPM and PUT was determined to have some effects on the activities of superoxide dismutase (SOD) and peroxidase (POD). 1 mM of SPM increased SOD activity, but PUT has no significant effect on SOD activity. On the other hand, POD activity was recorded to increase slightly in response to both concentrations of SPM and 1 mM of PUT. The results showed that such polyamine pretreated plants may become more tolerant to oxidative stress due to increases in the antioxidative enzymes and antioxidants.

Polyamines: Induction and Effect on Rust Disease Control of Bean

Two experiments were conducted to evaluate the potential effect of polyamine induction (putrescence, spermidine and spermine) in bean plants on control of rust disease caused by Uromyces appendiculatus under both greenhouse and field conditions. Three concentrations, 0.5, 1.0 and 1.5 mM of putrescine, ornithine and arginine were used as precursors of diamine putrescence, the triamine spermidine and tetraamine spermine. In the greenhouse, the disease severity and the number of pustules and uredospores were substantially reduced by all tested concentrations of polyamines precursors. At the same time, spraying of precursors of polyamines led to significant increases in levels of free putrescence, spermine and spermidine during the 21 days of experimental period. Meanwhile, treated leaves also exhibited significant increase in the amount of soluble conjugated putrescence, spermidine and spermine. These changes were accompanied by significant increase in the activity of soluble ornithine decarboxylase (ODC) and polyamine oxidase (PAO) during the 21 days of experimental period. Polyamines concentrations, ODC activity and PAO activity were greatly decreased in inoculated control treatment. Levels of free, soluble conjugated polyamines, ODC activity and PAO activity were greatly increased following treatment with putrescine at 1 mM. Moreover, significant increases in activities of plant defence related enzymes, peroxidase, polyphenoloxidase, free and conjugated phenol contents and pathogen related proteins were recorded in treated plants compared with untreated infected plants. In field trials, twice application of precursor of polyamines led to a significant reduction in rust disease infection and the number of pustules and uredospores during growth periods. Significant increases in growth characters and final yield were obtained in comparison with the untreated control. The most effective treatment was putrescine at 0.5 and 1.0 mM. However, high effect was also obtained by ornithine and arginine at 1.0 and 1.5 mM. It is concluded that the potential activity of these compounds may be related to the accumulation of diamine putrescence and polyamines spermidine and spermine and specifically to their toxicity and role in resistance. It was suggested that induction of polyamines may become a promising new approach for controlling rust disease of bean plants.

Effects of putrescine application on fruit set in ‘Housui’ Japanese pear ( Pyrus pyrifolia Nakai)

In Japan, artificial pollination is practiced to improve fruit set as well as fruit size and to obtain perfect round shapes in ‘Housui’ (S 3S 5) Japanese pear and most commercial cultivars that present gametophytic self-incompatibility. The period of artificial pollination application is limited by environmental conditions and the availability of a labor force. The present study aimed to determine if pre-pollination applications of putrescine (1.0 and 0.01 mM) positively affect fruit set in ‘Housui’ after hand-pollination. During 2002 and 2003, fruit set in late pollinated flowers increased with pre-pollination putrescine applications and concentrations of 1.0 mM had a better effect than 0.01 mM. In vitro pollination tests revealed that higher pollen germination was present in the stigmas of flowers sprayed with 1.0 mM of putrescine compared to the controls. Putrescine application did not affect post-pollination ethylene production in the styles. Moreover, in the styles of non-treated flowers, an increment of putrescine content and ethylene production after pollination was found, suggesting post-pollination responses and confirming the lack of antagonism between polyamines and ethylene at least during this process.

Brief Note : Improved in vitro embryo development of stenospermic grape by putrescine

The goal of this study was to determine the effect of putrescine, added to the culture medium, on the in vitro development of stenospermic grape (Vitis vinifera L) embryos. The cross breedings of Perlón x G.C88552 and Perlón x Argentina were used. 0 (control), 2 and 4 mM of putrescine were added to the immature seed's culture medium. In Perlón x Argentina, 2 mM of putrescine statistically increased the percentage of total embryos, direct germination, polyembryos and normal plants. In Perlón x G.C88552, only 2 mM of putrescine increased all the variables considered, eventually tripling the percentage of normal plants obtained. The results suggest that the endogenous concentration of putrescine may be a growth limiting factor. Adding putrescine to the culture medium of immature grape seeds is a legitimate resource to significantly increase the results of this technique.

Putrescine influences growth and production of coumarins in transformed and untransformed root cultures of witloof chicory (Cichorium intybus L. cv. Lucknow local)

The effect of putrescine on growth and production of two coumarins, esculin, and esculetin in the transformed and untransformed roots of chicory (Cichorium intybus L. cv. Lucknow local) was examined. To study the role of putrescine (Put) on growth and production of coumarins, polyamine inhibitors namely α-DL-difluromethylornithine (DFMO) and α-L-difluromethylarginine (DFMA) were used at 1 mM levels. Treatment with 1.5 mM of putrescine (Put) produced 1.96 - fold and 4.0 - fold increase in the growth of transformed and untransformed roots of chicory, respectively. The treatment with polyamine inhibitors showed much lower growth, as well as production compared with both 1.5 mM putrescine treatment and control in both transformed and untransformed chicory roots. The endogenous polyamines, both free and conjugated, were studied over the whole culture period, and it was seen that conjugated titers of all three polyamines viz., putrescine, spermidine and spermine were higher than level of free polyamines, throughout the culture period in both transformed and untransformed roots of chicory. Treatment in which polyamine inhibitors were used showed lower level of endogenous polyamines as compared with the 1.5 mM putrescine treated sample in both the systems. The treatment wherein putrescine was added at 1.5 mM level showed maximum accumulation of endogenous conjugated putrescine (2098.86±157.6 nmoles g−1 FW; 896.8±67.2 nmoles·g−1 FW), on the 14th day in both transformed and untransformed roots respectively. The production of esculin and esculetin was strictly correlated with growth in every treatment in both systems. Putrescine at 1.5 mM resulted in greater length of primary root in transformed (18.3±1.4 cm) and untransformed (6.86±0.51 cm) as compared with their respective controls (11±0.9 cm; 2.9±0.1cm) and greater number of secondary and tertiary roots. This study suggests that putrescine influences plant root development and differentiation, and it also provides insight into the morphological changes that occur in roots in response to the external supply of polyamines.

Effects of DFMO on glioma cell proliferation, migration and invasion in vitro.

The polyamine inhibitor DL-alpha-difluoromethylornithine (DFMO) is a specific irreversible inhibitor of ornithine decarboxylase which is a rate-limiting enzyme in the polyamine bio-synthesis pathway. The present study describes the effects of DFMO on glioma cell proliferation, migration and invasion using multicellular spheroids from three glioma cell lines (GaMg, U-251 Mg and U-87 Mg). 10 mM DFMO reduced cell migration in the three cell lines by about 30-50%. 1 mM putrescine, added together with DFMO inhibited the DFMO effect. A stronger effect was observed in the growth assay where 10 mM DFMO reduced the spheroid growth, for all cell lines, by 90%. This effect was also reversed by adding 1 mM of putrescine. In vitro tumor cell invasion experiments indicated after 3 days of confrontation, an extensive invasion also after 10 mM DFMO treatment. The brain aggregate volumes were reduced to about the same extent as in the absence of drug, suggesting essentially no effects of DFMO on the invasive process. It is concluded that the tumor spheroids retained their ability to invade normal brain tissue even after DFMO exposure. However, DFMO inhibited spheroid growth and cell migration which supports the notion that cell growth, migration and invasion are biological properties that are not necessarily related to each other.

Regulation of cadaverine and putrescine levels in different organs of chick‐pea seed and seedlings during germination

In chick‐pea (Cicer arietinum L.) seed germinated in the presence of 14C‐lysine, the latter is taken up and partly metabolised to cadaverine and TCA‐precipitable molecules. Labelled cadaverine is detectable in seedlings only after 3 days, on a labelled lysine‐containing medium, as confirmed also by the presence of lysine decarboxylase (LDC) activity, measured in the embryo axis and cotyledons of the seed and in the epicotyl, cotyledons, hypocotyl and roots of the seedling on the basis of 14CO2 evolution from the labelled precursor. Putrescine biosynthesis occurred only via arginine decarboxylase (ADC) activities in soaked seeds and via both ADC and ornithine decarboxylase (ODC) activities in seedlings. Both putrescine and cadaverine were present in soaked seed, and accumulated in very large amounts in the different portions of both 3‐ and 8‐day‐old seedlings, while spermidine and spermine titers were maintained at similar levels with respect to the seed. Diamine oxidase activity, measured by evaluating oxygen consumption in the presence of putrescine, was absent in ungerminated seed and appeared in 3‐ and 8‐day‐old seedlings. In order to clarify the metabolic relationships between cadaverine and the more common polyamines, gradients of biosynthesis, accumulation and degradation of putrescine and cadaverine along the seedling axis were compared, indicating that the two diamines behave similarly during seed germination and seedling development. Their conspicuous accumulation (up to 6 mM for putrescine) seems to be regulated mainly via oxidation rather than biosynthesis.

Evidence that spermine, spermidine, and putrescine are transported electrophoretically in mitochondria by a specific polyamine uniporter.

We present evidence that polyamine uptake into rat liver mitochondria is mediated by a specific polyamine uniporter. Polyamine transport is not mediated by the ornithine, lysine, or Ca2+ transporters of mitochondria. Polyamine transport is a saturable process, with apparent Km values of 0.13 mM for spermine, 0.26 mM for spermidine, and 1 mM for putrescine. These substrates are mutually competitive inhibitors, indicating a common transport system. Polyamine transport is strictly dependent on membrane potential and insensitive to medium pH, showing that these polycations are transported electrophoretically. Spermine, spermidine, and putrescine are taken up by rat liver mitochondria at rates that increase with increasing valence of the transported species. The activation enthalpies for transport were 24, 32, and 59 kJ/mol for putrescine, spermidine, and spermine, respectively. These values, which amount to about 12 kJ/mol per charge transferred, may be compared to a value of 76 kJ/mol observed for monovalent tetraethylammonium cation. Flux-voltage analysis is consistent with the hypothesis that the mitochondrial polyamine transporter catalyzes transport via a channel mechanism.