High Concentrations Of Putrescine Research Articles

Effects of Diets Based on Hydrolyzed Chicken Liver and Different Protein Concentrations on the Formation and Deamination of Biogenic Amines and Total Antioxidant Capacity of Dogs.

Biogenic amines are synthesized through the bacterial decarboxylation of amino acids, commonly found in high levels in animal by-product meals due to spoilage. Furthermore, biogenic amines and other metabolites can be produced by the fermentation of proteins in the hindgut according to the protein source and concentration of crude protein (CP) in the diet. Thus, this study aimed to evaluate two protein sources (poultry by-product meal (PBPM) and hydrolyzed chicken liver powder (HCLP)) and three CP concentrations (24, 32, and 40%) and their effects on the consumption and fecal excretion of biogenic amines, plasma monoamine oxidase (MAO) and diamine oxidase (DAO) activities, and total antioxidant capacity (TAC) of healthy adult dogs after 30 days of feeding the experimental diets. Twelve dogs were randomly distributed into six treatments (n = 6/treatment): PBPM24 (PBPM with 24% CP); PBPM32 (PBPM with 32% CP); PBPM40 (PBPM with 40% CP); HCLP24 (HCLP with 24% CP); HCLP32 (HCLP with 32% CP); HCLP40 (HCLP with 40% CP). The PBPM and PBPM-based diets had higher concentrations of putrescine, cadaverine, tyramine, histamine, agmatine, and total biogenic amines. In contrast, HCLP and HCLP-based diets contained higher concentrations of spermidine, phenylethylamine, and spermine. The PBPM and PBPM-diets had higher biogenic amine index (BAI) indicating lower quality due to the high content of putrescine, cadaverine and tyramine. Dogs fed diets with PBPM and higher protein concentrations consumed more putrescine, cadaverine, tyramine, agmatine, and total amines (p < 0.0001), while dogs fed with HCLP consumed more spermidine, phenylethylamine, and spermine (p < 0.0001). Fecal excretion of phenylethylamine was greater in dogs fed HCLP32 and HCLP40 diets (p = 0.045). Dogs fed with HCLP tended to excrete more spermidine and tryptamine via feces, while higher protein concentrations tended to increase fecal excretion of cadaverine (p < 0.10). Plasma MAO activity was higher in dogs fed HCLP24 and PBPM32 diets (p = 0.024). The plasma activities of DAO and TAC were not different between diets (p > 0.05). Although we did not evaluate the intestinal activities of MAO and DAO, our results suggest that healthy adult dogs have an efficient deamination process on the gut epithelium.

Modelling biogenic amines in fish meat in Central Europe using censored distributions

The aim of the study is to model concentrations of selected biogenic amines in various fish species (Atlantic salmon, Atlantic cod, striped catfish) bought in retail stores in Central Europe. Since the data contains non-detectable values, statistical methods for left-censored values from the exponential and Weibull distributions are applied and used to evaluate and compare the amount of biogenic amines in fish samples. Moreover, a risk of exceeding certain limits of biogenic amine concentrations to protect human health is determined. There are relatively high concentrations of putrescine, cadaverine and histamine in almost all fish species. Moreover, there was a significant difference in mean concentrations (distributions of concentrations, respectively) of histamine, tyramine and spermidine among the species.

Long-term culture with 2,4-dichlorophenoxyacetic acid affects embryogenic competence in sugarcane callus via changes in starch, polyamine and protein profiles

Somatic embryogenesis is a biotechnological tool with high application potential in the in vitro propagation and regeneration of crop plants, such as sugarcane. However, decreasing embryogenic competence is observed in embryogenic callus with successive subcultures, especially when the callus are maintained in the presence of 2,4-dichlorophenoxyacetic acid (2,4-d). Thus, the aim of this work was to investigate the morphological and molecular changes associated with the decreasing embryogenic competence in sugarcane embryogenic callus under long-term culture with or without 2,4-d. Sugarcane embryogenic callus were subcultured with 10 μM 2,4-d every 21 days for eight subcultures, and during each subculture, the callus were matured. In addition, the embryogenic callus from the first subculture after induction (S1) and after six subcultures with (S6) or without 2,4-d [S6(-)] were matured, and their histomorphological and histochemical features, endogenous polyamine levels and proteomic profiles were examined. The callus cultured with 2,4-d for a long time period showed reduced embryogenic competence after six subcultures, while callus cultivated in culture medium without 2,4-d maintained high embryogenic competence. In contrast to the callus in S6, those in the first subculture (S1) and S6(-) presented prominent nuclei, a high nucleus/cytoplasm ratio. Long-term culture with 2,4-d also affected polyamine (PA) metabolism, leading to high concentrations of putrescine (Put) and spermidine (Spd) in particular, and the synthesis and regulation of proteins, such as late embryogenesis abundant protein, chitinase, oleosin, and heat shock proteins. Therefore, we demonstrate that long-term culture with 2,4-d decreases embryogenic competence in sugarcane embryogenic callus. Loss in embryogenic competence in sugarcane callus by the long exposure to 2,4-d, is induced via changes in the synthesis/mobilization of reserves and protein abundance.

Putrescine modifies the pollen tube growth of tea (Camellia sinensis) by affecting actin organization and cell wall structure.

The aim of the current study was to examine the effect of different exogenous putrescine concentrations (200, 400, 600, and 800μM) on the tea pollen performance. It was shown that putrescine has a dose-dependent effect on pollen performance. Results exhibited that pollen germination and tube elongation were induced by 200 and 400μM putrescine treatment, especially, 400μM putrescine-enhanced pollen performance. However, pollen performance was inhibited by higher concentrations of putrescine. Putrescine concentrations above 400μM changed the actin filament distribution in pollen tubes by affecting the distribution of sucrose synthase enzyme. Alterations of the distribution on sucrose synthase enzyme also caused the alterations in the dispersion of cellulose and callose in the cell wall, and morphological alterations such as balloon-shaped and snake-shaped pollen tube tip accompanied them. Moreover, putrescine concentrations above 400μM caused a decrease of ROS level in apex and led to chromatin condensation of the generative nucleus. In conclusion, exogenous putrescine application can be used as a pollen performance enhancer at low concentrations while the high concentrations cause adverse effects reducing fertilization success.

Polyamines and antioxidant defense system are associated with cold tolerance in centipedegrass

Physiological responses to low temperature were analyzed in a chilling-tolerant centipedegrass (<i>Eremochloa ophiuroides</i>) accession, Shao Guan (SG), in comparison to the commercial cultivar, Common. Lower levels of ion leakage and higher chlorophyll (Chl) concentration were observed in SG than in Common during chilling stress. The maximum photochemical efficiency, the actual photosystem II (PSII) efficiency, photochemical quenching efficiency, and net photosynthetic rate were decreased during chilling stress in both genotypes, with higher levels of these parameters shown by SG than Common. In addition, higher activities of superoxide dismutase (SOD), catalase (CAT), ascorbate-peroxidase (APX) and glutathione reductase (GR), and higher concentrations of ascorbic acid (AsA) and glutathione (GSH) were observed in SG than in Common. Moreover, higher concentrations of putrescine (Put), spermidine (Spd), and spermine (Spm) were observed in SG than in Common. Correlation analysis indicated that SOD, CAT, APX and GR activities, and AsA and GSH concentrations showed high correlation to Put, while APX, GR, and AsA concentrations were correlated to Spd. Exogenous Put or Spd increased antioxidant enzyme activities and chilling tolerance. The results suggested that polyamine-regulated antioxidants are important for chilling tolerance in centipedegrass and protect plants against chilling induced oxidative damage.

Polyamines in tomato plants grown during an incidence of tospovirus exposure

This study aimed to evaluate the effect of an agrochemical mixture, Pyraclostrobin + Metiram (Cabrio Top)® (P + M), and Bacillus subtilis on polyamine levels and their potential relationship with plant growth stages. These experiments were conducted in an area of historical disease occurrence. Thirty-two hundred tomato plants (cv. “Saladinha Plus”) were used. The trays were divided into two groups; one group received a pre-treatment of P + M (3 g l −1) and Boscalid ® (0.3 g l −1), and no products were applied to the other half of the tray. After transplanting, the following spray treatments were used: P + M (2.0 g l −1), P + M (4.0 g l −1), B. subtilis (4.0 ml l −1) and Methamidophos® (1.0 ml l −1) for 20, 35, 50 and 65 days after (DAT). To analyze the free polyamine concentrations (putrescine, spermidine and spermine), the plant material was collected at 30, 45, 60, and 75 DAT. The fruit harvest and the assessment of the total production and average fruit weight were performed at 80 DAT by selecting 20 plants from each treatment group. Higher concentrations of putrescine and spermidine were found in the plants exposed to P + M at 4.0 g l −1, indicating that polyamine concentrations may be correlated with the plant’s resistance to stress. The optimal production and weight of the tomatoes were obtained following the application of P + M, demonstrating that this agrochemical mixture has great potential to protect tomato crop yields when applied during periods of high disease incidence.

Enhancing effect of lysine combined with other compounds on cephamycin C production in Streptomyces clavuligerus.

BackgroundLysine plays an important role in Streptomyces clavuligerus metabolism; it takes part in its catabolism, via cadaverine, and in its secondary metabolism, in which lysine is converted via 1-piperideine-6-carboxylate to alpha-aminoadipic acid, a beta-lactam antibiotic precursor. The role of lysine as an enhancer of cephamycin C production, when added to production medium at concentrations above 50 mmol l-1, has already been reported in the literature, with some studies attributing a positive influence to multifunctional diamines, among other compounds. However, there is a lack of research on the combined effect of these compounds on antibiotic production.ResultsResults from experimental design-based tests were used to conduct response surface-based optimization studies in order to investigate the synergistic effect of combining lysine with cadaverine, putrescine, 1,3-diaminopropane, or alpha-aminoadipic acid on cephamycin C volumetric production. Lysine combined with cadaverine influenced production positively, but only at low lysine concentrations. On the whole, higher putrescine concentrations (0.4 g l-1) affected negatively cephamycin C volumetric production. In comparison to culture media containing only lysine as additive, combinations of this amino acid with alpha-aminoadipic acid or 1,3-diaminopropane increased cephamycin C production by more than 100%.ConclusionThis study demonstrated that different combinations of lysine with diamines or lysine with alpha-aminoadipic acid engender significant differences with respect to antibiotic volumetric production, with emphasis on the benefits observed for lysine combined with alpha-aminoadipic acid or 1,3-diaminopropane. This increase is explained by mathematical models and demonstrated by means of bioreactor cultivations. Moreover, it is consistent with the positive influence of these compounds on lysine conversion to alpha-aminoadipic acid, a limiting step in cephamycin C production.

Lower polyamine levels in breast milk of obese mothers compared to mothers with normal body weight

Obesity is associated with risks for mother and infant, and the mothers' dietary habits influence breast milk composition. Polyamines are secreted in breast milk and are essential for the regulation of intestinal and immune function in newborns and infants. The present study aimed to investigate the level of polyamines in human milk obtained from obese and normal weight mothers at different times of lactation. Breast milk from 50 mothers was obtained at day 3, and at 1 and 2months after delivery. The mothers had normal body weight [body mass index (BMI)<25kgm(-2) ] or were obese (BMI>30kg/m(2) ). A subgroup of obese mothers participated in a weight reduction programme during pregnancy. Polyamines were analysed using high-performance liquid chromatography. The total polyamine content was significantly lower at all times in breast milk from obese mothers compared to milk from controls. Spermine levels did not differ between groups at any time in contrast to the levels of putrescine and spermidine. Putrescine concentrations were highest on day 3 and spermidine and spermine were highest at 1month of lactation. The obese mothers, who received dietary advice during pregnancy based on the Nordic Nutrition Recommendations, had higher concentrations of putrescine and spermidine in their milk than the obese mothers without any intervention. Polyamine concentrations were lower in breast milk from obese mothers compared to mothers with a normal weight. General dietary intervention in obese mothers increased the polyamine levels, suggesting that the low levels in obesity were at least partly associated with food habits. However, the consistency of spermine suggests a special metabolic function of this polyamine.

Pre-harvest Application of Putrescine Influences Japanese Plum Fruit Ripening and Quality

To investigate the role of pre-harvest application of putrescine (PUT) in regulating fruit ripening and quality of early-, mid- and late-season maturing Japanese plum fruit, whole trees were sprayed with an aqueous solution containing PUT (0, 0.1, 1.0 and 2.0 mM) one week before anticipated commercial harvest for each cultivar separately. The PUT (2.0 mM) treatment reduced the respiration rate and ethylene production more than untreated fruit during fruit ripening at ambient temperature (20 ± 1 °C). Activities of ACS and ACO enzymes, and ACC content were delayed and suppressed in all plum cultivars and these effects were more pronounced with higher PUT concentrations. PUT application reduced the fruit softening, soluble solids content, titratable acidity ratio, the levels of ascorbic acid, total carotenoids and total antioxidants in all plum cultivars. 'Black Amber' did not exhibit any change in fruit color parameters, while, PUT application to 'Amber Jewel' and 'Angelino' fruit, delayed the changes in chroma value and hue angle during fruit ripening. In conclusion, pre-harvest application of 2.0 mM PUT delayed the fruit ripening with reduced respiration rate, ethylene production, activities of ACS and ACO enzymes, ACC content, fruit softening, levels of ascorbic acid, total carotenoids and total antioxidants in Japanese plum.

Identification and Characterization of a Diamine Exporter in Colon Epithelial Cells

SLC3A2, a member of the solute carrier family, was identified by proteomics methods as a component of a transporter capable of exporting the diamine putrescine in the Chinese hamster ovary (CHO) cells selected for resistance to growth inhibition by high exogenous concentrations of putrescine. Putrescine transport was increased in inverted plasma membrane vesicles prepared from cells resistant to growth inhibition by putrescine compared with transport in inverted vesicles prepared from non-selected cells. Knockdown of SLC3A2 in human cells, using short hairpin RNA, caused an increase in putrescine uptake and a decrease in arginine uptake activity. SLC3A2 knockdown cells accumulated higher polyamine levels and grew faster than control cells. The growth of SLC3A2 knockdown cells was inhibited by high concentrations of putrescine. Knockdown of SLC3A2 reduced export of polyamines from cells. Expression of SLC3A2 was suppressed in human HCT116 colon cancer cells, which have an activated K-RAS, compared with their isogenic clone, Hkh2 cells, which lack an activated K-RAS allele. Spermidine/spermine N(1)-acetyltransferase (SAT1) was co-immunoprecipitated by an anti-SLC3A2 antibody as was SLC3A2 with an anti-SAT1 antibody. SLC3A2 and SAT1 colocalized on the plasma membrane. These data provide the first molecular characterization of a polyamine exporter in animal cells and indicate that the diamine putrescine is exported by an arginine transporter containing SLC3A2, whose expression is negatively regulated by K-RAS. The interaction between SLC3A2 and SAT1 suggests that these proteins may facilitate excretion of acetylated polyamines.

Dietary Putrescine Reduces the Intestinal Anticarcinogenic Activity of Sulindac in a Murine Model of Familial Adenomatous Polyposis

: The nonsteroidal antiinflammatory drug sulindac displays chemopreventive activity in patients with familial adenomatous polyposis (FAP). Sulindac metabolites induce apoptosis in colon tumor cells, in part, by a polyamine-dependent mechanism that can be suppressed with exogenous putrescine. To determine the relevance of this mechanism in animals, we treated ApcMin/+ mice, a model of human FAP, with sulindac alone or in combination with dietary putrescine. Sulindac increased steady-state RNA levels and enzymatic activity of the polyamine catabolic enzyme spermidine/spermine N1-acetyltransferase and intestinal levels of monoacetylspermidine, spermidine, and spermine in the small intestine of mice. Sulindac also decreased the activity of the biosynthetic enzyme ornithine decarboxylase but not adenosylmethionine decarboxylase (AMD). Dietary putrescine increased intestinal putrescine contents, whereas the combination of dietary putrescine and sulindac yielded the highest levels of intestinal putrescine and correlated with a statistically significant reduction in AMD enzyme activity. Dietary putrescine did not statistically significantly increase tumorigenesis, although it significantly increased the grade of adenoma dysplasia (P < 0.05). The effectiveness of sulindac to suppress intestinal carcinogenesis was partially abrogated by dietary putrescine. These data suggest that sulindac exerts at least some of its anticarcinogenic effects in mice via a polyamine-dependent mechanism. Because high concentrations of putrescine can be found in certain dietary components, it may be advantageous to restrict dietary putrescine consumption in patients undergoing treatment with sulindac.

The influence of polyamines on apricot ovary development and fruit set

AbstractPolyamine (PA) concentrations of ovaries of two apricot cultivars, ‘S405‐17’ and ‘Bergeron’, collected at three stages of floral development, were analysed. The relationships between PA profiles, ovule development and fruit load between the two apricot cultivars were also determined. We show that PA levels vary with ovary development, depending on the cultivar. Higher concentrations of putrescine (PUT), spermidine and spermine were found in S405‐17 cultivar at all phenological stages. In addition, S405‐17 cultivar had more developed ovules and a higher fruit load than Bergeron. Moreover, the exogenous application of 10 mM PUT in Bergeron increased the percentage of functional ovules from 17.1% (control) to 33.3%. These results prove the effects of PAs on ovary development and indicate the possible improvement of apricot ovule development by their exogenous application. All these results define the relationship between PA content and ovule development in apricot. Further studies would confirm the use of free endogenous PA concentrations as markers of the developmental stage of the ovary, because determination of PA contents is easier and faster than serial sectioning.

Excretion of Putrescine and Spermidine by the Protein Encoded by YKL174c (TPO5) in Saccharomyces cerevisiae

The properties of the protein encoded by YKL174c (TPO5) were studied. It was found that TPO5 excretes putrescine effectively and spermidine less effectively. Gamma-aminobutyric acid slightly inhibited the excretion of putrescine, but basic amino acids did not affect excretion, suggesting that TPO5 preferentially recognizes polyamines. Accordingly, yeast cells transformed with the plasmid encoding YKL174c (TPO5) were resistant to toxicity caused by 120 mm putrescine or by 3 mm spermidine, and a mutant with a disrupted YKL174c (TPO5) gene was sensitive to toxicity by 90 mm putrescine. The growth of this mutant was faster than that of the wild-type strain. In parallel, there was an increase in putrescine and spermidine content of the YKL174c (TPO5) mutant compared with wild-type. It is noted that TPO5 functions as a suppressor of cell growth by excreting polyamines. The level of YKL174c (TPO5) mRNA was increased by the addition of polyamines to the medium. The degree of induction of the mRNA was spermine > spermidine > putrescine. The subcellular localization of TPO5 was determined by immunostaining of hemagglutinin-tagged TPO5, and it was found on Golgi or post-Golgi secretory vesicles. Excretion of putrescine and spermidine by TPO5 was reduced in cells that have mutations in the secretory or endocytic pathways, indicating that both processes are involved in the excretion of polyamines.

Polyamines and colon cancer.

In colon cancer, the activities of polyamine-synthesizing enzymes and polyamine content are increased 3-4-fold over that found in the equivalent normal colonic mucosa, and polyamines have even been attributed as markers of neoplastic proliferation in the colon. Furthermore, and in contrast with all other cell systems in the body, normal and neoplastic cells in the colon are exposed to high concentrations of putrescine from the lumen, synthesized by colonic microflora. While such a high polyamine supply may be of benefit in non-neoplastic colonic mucosal growth, the role of luminal polyamines in colon cancer is a clear concern. Luminal polyamines are readily taken up by neoplastic colonocytes, they are utilized in full to support neoplastic growth, and their uptake is strongly up-regulated by the mitogens known to play an important role in colonic carcinogenesis. Inhibition of polyamine synthesis and their uptake, impaired utilization of exogenous polyamines, and enhanced catabolism of polyamines in neoplastic colonocytes are therefore logical approaches in the chemoprevention of colorectal cancer.

A Novel Calcium-Independent Enzyme Capable of Incorporating Putrescine into Proteins

A Ca++-independent enzyme capable of incorporating [3H]-putrescine into proteins was detected in the rat intestine mucosa. The Ca++-independent incorporation of [3H]-putrescine into proteins was temperature-, pH-, time-, and dose-dependent. However, this enzyme was absent in the gastric mucosa. Similar to testicular Ca++-dependent transglutaminase, the optimal pH of intestinal Ca++-independent enzyme was 9.0. At 10−5M or less putrescine concentrations, the Ca++-independent enzyme in an intestinal cytosol preparation showed a greater activity than did the Ca++-dependent transglutaminase. However, at higher putrescine concentrations, the latter showed a greater activity than did the former. Both the intestinal Ca++-dependent and independent enzymes were inhibited by cystamine, thermal labile at 50°C and precipitated by 30 to 50% saturation of ammonium sulfate. The fact that these two enzymes shared many similar characteristics, with the exceptions of Ca++-requirement, suggests that they may have similar active site and intrinsic molecular function(s).

Cloning and disruption of the ornithine decarboxylase gene of Ustilago maydis: evidence for a role of polyamines in its dimorphic transition.

The gene encoding ornithine decarboxylase (ODC) from Ustilago maydis was cloned. A conserved PCR product amplified from U. maydis DNA was synthesized and used to screen a genomic library of the fungus. Alignment of its deduced protein sequence with those of other cloned ODCs showed a high degree of homology. Gene replacement was obtained by removal of a central part of the gene and insertion of the hygromycin resistance cassette. The null mutant thus obtained displayed no ODC activity and behaved as a polyamine auxotroph. This result is evidence that a single ODC gene exists in the fungus, and that U. maydis utilizes the ODC pathway as the only mechanism for polyamine biosynthesis. When grown in polyamine-containing media, the null mutant accumulated a polyamine pool which further sustained its normal rate of growth in polyamine-free media for approximately 12-16 h. When putrescine concentrations lower than 0.5 mM were employed, the mutant grew at a normal rate but was unable to engage in the dimorphic transition. Under conditions favourable for mycelial growth, the mutant grew with a yeast-like morphology in liquid media, and formed smooth colonies consisting of yeast cells on solid media. Reversion to normal dimorphic phenotype required high concentrations of putrescine or spermidine. These results are evidence that concentrations of polyamines higher than those necessary to sustain vegetative growth are required for the dimorphic transition in U. maydis.

Polyamine Distribution in Actinomycetes with Group B Peptidoglycan and Species of the Genera Brevibacterium, Corynebacterium, and Tsukamurella

Polyamine patterns of 75 strains of actinobacteria belonging to the genera Agrococcus, Agromyces, Aureobacterium, Brevibacterium, Clavibacter, Corynebacterium, Curtobacterium, Microbacterium, Rathayibacter, and Tsukamurella were analyzed in order to investigate the suitability of this approach for differentiation within this group. The results revealed that the overall polyamine contents differ significantly among genera and that various patterns are present in actinobacteria. One characteristic pattern found in the genera Clavibacter, Rathayibacter, and Curtobacterium included a high polyamine concentration, and the polyamines were mainly spermidine and spermine. This feature distinguished the 2,4-diaminobutyric acid-containing genera Rathayibacter, Clavibacter, and Agromyces, which contained low concentrations of polyamines. Strains of the genus Brevibacterium were characterized by the presence of high concentrations of cadavarine and usually high concentrations of putrescine. Members of the genus Corynebacterium had relatively low polyamine contents, and usually spermidine was the major polyamine. A similar polyamine pattern was detected in the species of the genus Tsukamurella. No homogeneous polyamine patterns were detected in representatives of the genera Microbacterium and Aureobacterium, which are phylogenetically intermixed (M. Takeuchi and A. Yokota, FEMS Microbiol. Lett. 124:11–16, 1994). The results of polyamine analyses are in good agreement with the genetic heterogeneity within the actinobacteria and demonstrate that polyamine patterns are suitable for use in classification of actinobacterial taxa.

Tolerance to Putrescine Toxicity in Chinese Hamster Ovary Cells Is Associated with Altered Uptake and Export

When Chinese hamster ovary (CHO) cells were cultured with low concentrations of putrescine (< 5 mM) their cell cycle time increased significantly and a fraction of the cells died. A cell line tolerant to the cytotoxic and growth inhibitory effects of millimolar concentrations of putrescine was developed by growing CHO cells over many months in increasing concentrations of the polyamine. A putrescine-tolerant cell line was obtained which was capable of growing in concentrations up to 25 mMputrescine and displayed growth and cell division rates similar to the original untreated/parental CHO cells. The tolerant cells grown in putrescine displayed relatively high intracellular putrescine yet the cell-associated putrescine concentration was estimated to be 10-fold less than the culture medium level. This high concentration of cellular putrescine diminished within 60 min when the cells were changed to non-putrescine-containing media. The putrescine-tolerant phenotype was further characterized in regards to the mechanisms involved in putrescine uptake, efflux, and biosynthesis. The parental and tolerant cell lines had similar or identical levels of cellular spermidine and spermine and no differences in the acetylated polyamine pools or diamine oxidase activity. The activity of ornithine decarboxylase was also similar in the two cell lines in both the presence and the absence of ornithine. The tolerant cells, however, had a decreased uptake rate for putrescine. The tolerant cell line also showed a greatly enhanced ability to export putrescine, especially when treated with ornithine, suggesting that an upregulated polyamine export system may be present in the tolerant cells which could be responsible for the increased cell survival in high putrescine concentrations. The data are discussed in regard to the potential for identifying the transport protein(s) responsible for the maintenance of nontoxic intracellular concentrations of putrescine in a tolerant cell line grown in putrescine.

Growth, Potassium and Polyamine Concentrations of Scots Pine Seedlings in Relation to Potassium Availability under Controlled Growth Conditions

Summary Scots pine ( Pinus sylvestris L.) seedlings were grown under controlled growth conditions with three relative addition rates (2, 4 and 6 % RAR per day) of potassium. The relative growth rate (R G ) of the seedlings, and the potassium, nitrogen, phosphorus and free polyamine concentrations of the needles and roots were measured during the growth period. Visible symptoms of potassium deficiency developed in the needles at the lowest potassium level after 6 weeks. Although the needle potassium concentrations and the relative growth rate correlated positively, the decrease in potassium from the highest K level (6 % RAR) to the medium one (4 % RAR) affected only slightly the relative growth rate per day, which decreased from RG 5.8 % to 5.5 %. At the same time putrescine accumulated in needle and root tissues. A clear decrease in the relative growth rate from RG 5.5 % at the 4 % RAR level to RC, 4.7 % at the lowest 2 % RAR level coincided with the high putrescine concentrations and low spermidine and spermine concentrations of the needles at the 2 % RAR level. The spermidine and spermine concentrations of the roots were lower than in the needles and at about the same level in all the treatments. These results show that the putrescine concentrations indicate the potassium status of the seedlings and that spermidine and spermine may be involved in changes of the growth rate of the Scots pine seedlings under varying potassium nutrition.

Putrescine active uptake system in the Trypanosomatid Crithidia fasciculata.

Using the insect Trypanosomatid Crithidia fasciculata as a model parasite of mammalian pathogenic flagellates, i.e. Leishmania and Trypanosoma spp., we have studied the kinetic and regulatory characteristics of the polyamine uptake system. Putrescine transport was age-dependent with maximum expression values at the proliferative logarithmic phase. Putrescine transport in Crithidia fasciculata was energy-dependent and against a putrescine concentration gradient. The integrity of the membrane sulfhydryl groups was absolutely required for optimum transport rates. The specificity of this mechanism was studied in the presence of a series of different chain length aliphatic diamines, showing the high specificity for putrescine and the poor effect of this series at the highest concentration analyzed as well as the higher polyamines spermidine and spermine. Finally, the well-known inhibitor of polyamine biosynthesis, DFMO, led to an upward regulation of putrescine uptake correlating with the depletion of intracellular polyamine pool. In addition, the presence of high concentrations of putrescine in the culture medium produced a downward regulation of this system.