Polyamine- and insulin-like growth factor-I-mediated proliferation of porcine uterine endometrial cells: a potential role for spermidine/spermine N(1)-acetyltransferase during peri-implantation

Insulin-like growth factor-I (IGF-I) and the polyamine catabolic enzyme spermidine/spermine N(1)-acetyltransferase (SSAT) are progesterone-regulated genes with maximal expression at peri-implantation in the porcine uterine endometrium. However, while IGF-I stimulates cell proliferation, SSAT, by acetylating the naturally occurring polyamines (PA) spermine (SPM) and spermidine (SPD), typically functions as a cell growth inhibitor. The present study examined the functional relationships of IGF-I, SSAT, and PA in the control of endometrial cell proliferation. Northern blot analysis indicated that SSAT mRNA levels change with distinct pregnancy stages, in contrast to those for the PA biosynthetic enzyme ornithine decarboxylase (ODC). Primary cultures of luminal and glandular epithelial (LE, GE) and stromal (ST) cells isolated from Day 12 pregnant pig endometrium had IGF-I mRNA levels for ST > LE > GE cells. The mRNA levels for SSAT and ODC were transiently diminished by IGF-I treatment, but only in GE cells. By contrast, SPM and SPD increased SSAT mRNA levels in GE and ST cells, but increased ODC mRNA levels only in GE cells. IGF-I, putrescine (PUT), and SPM individually increased cellular DNA synthesis as measured by tritiated thymidine incorporation in GE and ST cells, while SPD had an effect only in ST cells. IGF-I enhanced the proliferative effect of each PA in GE cells, but only of SPD in ST cells. The mitogen-activated protein kinase inhibitor, PD98059, inhibited the induction by SPM of GE cell DNA synthesis but not that of IGF-I. Wortmannin, a phosphatidylinositol-3-kinase inhibitor had no effect on either IGF-I or SPM induction of GE cell DNA synthesis. The relative concentrations of SPM, SPD, and PUT in uterine luminal fluids differed, with the levels for each PA higher at pregnancy Day 12 than at 11.5. These results suggest that IGF-I and PA act through distinct signaling pathways to mediate cell-type-specific growth of early pregnancy pig uterine endometrium. Further, SSAT, through its control of intracellular PA levels, likely plays a modulatory role in the establishment of an optimal uterine environment for successful embryo attachment.     

Changes in polyamines, c-myc and c-fos gene expression in osteoblast-like cells exposed to pulsed electromagnetic fields

Pulsed electromagnetic field (PEMF) stimulation promotes the healing of fractures in humans, though its effect is little known. The processes of tissue repair include protein synthesis and cell differentiation. The polyamines (PA) are compounds playing a relevant role in both protein synthesis processes and cell differentiation through c-myc and c-fos gene activation. Since several studies have demonstrated that PEMF acts on embryonic bone cells, human osteoblast-like cells and osteosarcoma TE-85 cell line, in this study we analyzed the effect on cell PAs, proliferation, and c-myc and c-fos gene expression of MG-63 human osteoblast-like cell cultures exposed to a clinically useful PEMF. The cells were grown in medium with 0.5 or 10% fetal calf serum (FCS). c-myc and c-fos gene expressions were determined by RT-PCR. Putrescine (PUT), spermidine (SPD), or spermine (SPM) levels were evaluated by HPLC. [(3)H]-thymidine was added to cultures for DNA analysis. The PEMF increased [(3)H]-thymidine incorporation (P < or = .01), while PUT decreased after treatment (P < or = .01); SPM and SPD were not significantly affected. c-myc was activated after 1 h and downregulated thereafter, while c-fos mRNA levels increased after 0.5 h and then decreased. PUT, SPD, SPM trends, and [(3)H]-thymidine incorporation were significantly related to PEMF treatment. These results indicate that exposure to PEMF exerts biological effects on the intracellular PUT of MG-63 cells and DNA synthesis, influencing the genes encoding c-myc and c-fos gene expression. These observations provide evidence that in vitro PEMF affects the mechanisms involved in cell proliferation and differentiation.     

Effects of polyamines on the release of gonadotropin-releasing hormone and gonadotropins in developing female rats

Polyamines, putrescine (PUT), spermidine (SPD), spermine (SPM), and agmatine (AGM), are polycationic amines related to multiple cell functions found in high concentrations during the development of hypothalamus and pituitary. In previous works, we demonstrated that alpha-difluoromethylornithine (DFMO), an inhibitor of polyamines biosynthesis, induced a delay in puberty of female rats, accompanied by high, sustained follicle-stimulating hormone (FSH) levels during the infantile period. Also, DFMO treatment induced changes in polyamine concentration both in hypothalamus and pituitary of rats, mainly a decrease of PUT and SPD, an increase in SPM, and no change in AGM. In the present work, we investigated the direct effects of polyamines on the secretion of hypothalamic GnRH and pituitary gonadotropins in 6- and 15-day-old female rats. In 6-day-old animals, in vitro incubations with PUT, SPD, and AGM of hypothalami or anterior pituitaries were able to inhibit GnRH, FSH, and leutinizing hormone (LH) secretion, respectively. SPM showed a nonspecific transient inhibitory effect on FSH. When challenged with either high K(+) (hypothami) or GnRH (pituitaries), the tissues incubated in the presence of polyamines showed no differences when compared with their controls. No effects of polyamines in 15-day-old rats in either tissue were observed. Pituitary cell cultures of 6-day-old animals incubated with DFMO for 4 days showed a significant increase in FSH, but not in LH. We conclude that high PUT, SPD, and AGM levels during the first 10 days of life are important for the development of the hypothalamic-hypophyseal unit, probably related to an inhibitory effect on GnRH and gonadotropins. Therefore, polyamine participation, especially PUT and SPD, is of importance in the regulation of GnRH and gonadotropin secretion in the neonatal and infantile periods, critical stages in the establishment of sexual differentiation.     

Polyamine metabolism in McCoy cells: III. Comparative studies of the metabolic fate of exogenous putrescine in human fibroblasts and McCoy cultures

The fate of exogenously added 14C-putrescine following incubation for 24 hours with McCoy and human skin fibroblast cultures was examined. The nature of the polyamine derivatives found were quite different indicative of a difference in the cellular metabolism of polyamines. Exogenously added putrescine (PUT) was metabolized by both McCoy and human skin fibroblast cultures to form spermidine (SPD), spermine (SPM), gamma-aminobutyric acid (GABA) and some unidentified compounds. Within the experimental period of observation, human cultured fibroblasts metabolized PUT more efficiently than McCoy cells and converted more than 50% of it into SPD, SPM, GABA and unknown compounds. Monoacetyl putrescine (MAP) was formed by human skin fibroblasts. It was mainly identified in the culture medium. No MAP was detectable either intracellularly or extracellularly in McCoy cultures. The percentage of 14C-radioactivity found as PUT in the culture medium was greater in McCoy cells (86.0%) than in human fibroblasts (53.9%). The reverse was true for the percentage distribution of 14C-radioactivity as PUT inside the cells. No low Mr conjugates of SPD or SPM were found in the medium or intracellularly with either culture type. Some low Mr putrescine conjugates were found in the culture media; these were identified by the liberation of PUT upon acid hydrolysis.     

Antizyme (AZ) regulates intestinal cell growth independent of polyamines

Since antizyme (AZ) is known to inhibit cell proliferation and to increase apoptosis, the question arises as to whether these effects occur independently of polyamines. Intestinal epithelial cells (IEC-6) were grown in control medium and medium containing 5 mM difluoromethylornithine (DFMO) to inhibit ODC, DFMO + 5 µM spermidine (SPD), DFMO + 5 µM spermine (SPM), or DFMO + 10 µM putrescine (PUT) for 4 days and various parameters of growth were measured along with AZ levels. Cell counts were significantly decreased and mean doubling times were significantly increased by DFMO. Putrescine restored growth in the presence of DFMO. However, both SPD and SPM when added with DFMO caused a much greater inhibition of growth than did DFMO alone, and both of these polyamines caused a dramatic increase in AZ. The addition of SPD or SPM to media containing DFMO + PUT significantly inhibited growth and caused a significant increase in AZ. IEC-6 cells transfected with AZ-siRNA grew more than twice as rapidly as either control cells or those incubated with DFMO, indicating that removal of AZ increases growth in cells in which polyamine synthesis is inhibited as well as in control cells. In a separate experiment, the addition of SPD increased AZ levels and inhibited growth of cells incubated with DFMO by 50 %. The addition of 10 mM asparagine (ASN) prevented the increase in AZ and restored growth to control levels. These results show that cell growth in the presence or absence of ODC activity and in the presence or absence of polyamines depends only on the levels of AZ. Therefore, the effects of AZ on cell growth are independent of polyamines.     

Analyzing the effects of exogeneous polyamines and growth regulators on plating efficiency of sweet potato protoplasts using a central composite test design

The effects of exogenous polyamines and growth regulators on plating efficiency of greenhouse-grown sweet potato (Ipomoea batatas Lam.) petiole protoplasts after six days were analyzed using a central composite test design. The medium components screened were 1-naphthaleneacetic acid (NAA), 6-benzylaminopurine (BAP), putrescine (PUT), spermidine (SPD), and spermine (SPM), each at five concentrations. Stepwise multiple regression analysis revealed significant interaction of NAA with BAP, PUT, and SPD as reflected in plating efficiencies. The interactions of NAA with BAP, and with SPD, were positive. The interaction of NAA and PUT appeared complex. A slight negative interaction was detected between PUT and SPM. These results indicated that plating efficiency of sweet potato protoplasts is highly sensitive to the concentrations of the medium components tested and it should be possible to further optimize the plating medium. Among the media formulations tested, the highest plating efficiency (10.8% after 6 days) was observed with NAA at 4.5 uM, BAP at 1.5 uM, PUT at 35.0 uM, SPD at 5.0 uM, and SPM at 2.5 uM.     

INFLUENCE OF POLYAMINES ON THE SPORULATION OF GRATELOUPIA (HALYMENIACEAE,RHODOPHYTA)1

Polyamines (PAs) such as putrescine (PUT), spermidine (SPD), and spermine (SPM) are ubiquitous aliphatic amines involved in widely varying physiological behavior, but particularly they are actively involved in cell growth, division, and differentiation during reproductive events in plants. The contents of PUT, SPD, and SPM in infertile and fertile thalli of the red macroalga Grateloupia sp. were compared, and the results revealed a significant decrease in quantity from infertile to fertile status. At the enzymatic level, l ‐ornithine decarboxylase (ODC) was mainly detected, and l ‐arginine decarboxylase activity was not diminished by the inhibition of ODC. The maximum enzymatic activities, within the range of activities observed, correlated with the lower levels of polyamines in fertile thalli. In culture, SPM promoted the maturation of cystocarps to the eventual liberation of spores from aseptic fertile explants. PAs accumulated in cultivated explants as compared with noncultivated, but exogenous SPM addition further increased the endogenous SPM. The addition of berenyl, cordycepin, cyclohexylamine, dicyclohexylamine, and aurintricarboxylic acid blocked the synthesis in culture at the level of PUT, and partially at SPD and SPM synthesis, but the addition of SPM restored the levels of SPD and SPM as SPM accumulated, and they appeared to interconvert each other. The results obtained suggest that the culture in presence of SPM restored a deficient SPM situation in fertile explants, thus promoting sporulation.     

Covalent modifications of antitetanus F(ab')2 fragments with natural and synthetic polyamines and their effects on the antibody endocytosis in cultured HL60 cells

For antibody therapeutics to succeed when intracellular target molecules are involved, a strategy must be applied to increase the delivery of antibodies into cells to reach their targets. Antibody cationization by chemical conjugation of a polyamine could be one such strategy. Both natural polyamines with increasing net charge valencies (putrescine, PUT; spermidine, SPD; and spermine, SPM) and a synthetic polyamine (hexamethylenediamine, HMD) can be used to cationize antibodies, but no comparison of the respective effects of these polyamines on intracellular delivery of antibodies has been performed yet. This study describes the covalent modification of antitetanus F(ab') 2 with these four polyamines using different reaction conditions, and compares the effects of these modifications on antibody interaction with cultured HL60 cells. The cationized antibodies retained > or =80% of the binding activity of the unmodified F(ab') 2 with regard to tetanus toxin, as measured by an antigen-binding capture enzyme immunoassay. This same method was used to quantify the amount of cell-associated F(ab') 2 following incubation with HL60 cells. Cationization was shown to enhance cell interaction of the F(ab') 2 : the higher the number of coupled polyamine molecules, the greater the amount of antibody associated with the cells. Moreover, coupling the F(ab') 2 to the SPD and SPM polyamines had greater effect on cell interaction than coupling the F(ab') 2 to the PUT and HMD diamines. Internalization of the cationized antibodies by the HL60 cells was demonstrated by confocal microscopy. This technique also showed that SPD and SPM were more effective than PUT and HMD in terms of intracellular delivery of the F(ab') 2 . It follows from all these results that electrostatic interaction involving charge density plays a predominant role in the endocytic transport mechanism of the F(ab') 2 modified with these polyamines. However, coupling the F(ab') 2 to SPM and SPD yielded the same maximum effects in terms of cell interaction, although coupling SPM was expected to increase the antibody net charge valency more than coupling SPD. This finding suggests that the effective global charge for the cell interaction and uptake of polyamine-modified antibodies does not simply correspond to the addition of the ionizable amine functions on the coupled polyamines, and that other factors may come into play.     

Polyamine Changes and Chilling Injury in Cold-stored Loquat Fruits

Free polyamine levels (spermine (SPM), spermidine (SPD), and putrescine (PUT)) were determined using thin-layer chromatography and fluorometric method in loquat (Eriobotrya japonica Lindl. cv. Dahongpao) fruits stored at 1℃ and 12℃ and in postharvest SPM treated fruits stored at 1℃ respectively to investigate the relationship between changes in polyamines and chilling injury. In the loquat fruits stored at 1℃, SPM level decreased gradually in the first two weeks, then increased sharply and reached a peak value after three weeks, thereafter it decreased rapidly. SPD level decreased steadily during the first three weeks and increased significantly afterwards. PUT level evolved in a similar way as the SPM level did except that it increased slowly in the first two weeks. The fruit showed symptom of chilling injury manifested as flesh leatheriness after three weeks. However, no significant increase and decrease of these three polyamines was detected during storage at the nonchilling temperature (12℃). The SPM-treated fruits maintained high levels of SPM and SPD and remained low level of PUT during storage at 1℃, and no symptom of chilling injury was observed. These results suggested that the increase in SPM level in response to chilling exposure might serve as a defense mechanism against chilling injury while the accumulation of PUT could be a cause of the stress-induced injury and the increase in SPD level could be a consequence of this kind of stress.     

Electric organ polyamines and their effects on the acetylcholine receptor

1. The electric organ of Torpedo nobiliana contained putrescine (PUT), spermidine (SPD), spermine (SPM), and cadaverine (CAD). Traces of acetylated SPD and SPM were occasionaly seen. 2. Upon fractionation of the tissue by differential centrifugation, the polyamines (PA) were found predominantly in the soluble fraction. The postsynaptic membrane fraction, containing a high concentration of acetylcholine receptor (AChR), was proportionally enriched in SPM. The molar ratio of SPM to AChR was approximately two in these membranes. 3. The effect of exogeneous PA on AChR function was studied by two methods: carbamoylcholine (CCh)-dependent 86Rb+ influx into receptor-rich membrane vesicles and [alpha-125I]bungarotoxin (Bgt) binding to the AChR. 4. SPM inhibited both ion influx and the rate of Bgt binding at concentrations above 1 mM, and therefore it appears to act as a competitive antagonist of the AChR. 5. At submicromolar concentrations, and only after preincubation with the receptor-rich membrane, SPM and PUT increased the ion influx by about 20% over control values. 6. Preincubation with 100 nM SPM did not affect the equilibrium binding of iodinated toxin or the rate of toxin binding, and therefore SPM was not uncovering new receptors. 7. By measuring the initial rate of toxin binding after different periods of preincubation with 1 microM CCh, the rate of the slow phase of receptor desensitization was determined. This rate was not changed by 100 nM SPM. 8. Although these results suggest that at low concentrations SPM is a positive modulator of the AChR, the precise mechanism of action is not determined yet.     

Paraquat toxicity is reduced by polyamines in rice leaves

The protective effect of polyamines against paraquat (PQ) toxicity of rice (Oryza sativa) leaves was investigated. PQ treatment resulted in a higher putrescine (PUT) and lower spermidine (SPD) and spermine (SPM) levels in rice leaves. Pretreatment with SPD and SPM, which resulted in a 10- and 20-fold increase in endogenous level of SPD and SPM, respectively, reduced PQ toxicity (30%). Limited reduction of PQ toxicity by exogenous SPD and SPM is most likely due to the fact that they are not readily transported in rice leaf cells and localized to those areas along the cut edges of detached rice leaves [4]. PUT pretreatment did not increase endogenous SPD and SPM levels and had no effect on reducing PQ toxicity. It was found that 1,10-phenanthroline, an iron chelator, treatment reduced the toxicity of PQ (35%) and increased the levels of SPD (27%). The results indicate that reduction of PQ toxicity by SPD and SPM is due to increased activities of catalase (18%) and peroxidase (40%).     

Polyamines and the Cell Cycle of Catharanthus roseus Cells in Culture

Investigation was made on the effect of partial depletion of polyamines (PAs), induced by treatment with inhibitors of the biosynthesis of PAs, on the distribution of cells at each phase of the cell cycle in Catharanthus roseus (L.) G. Don. cells in suspension cultures, using flow cytometry. More cells treated with inhibitors of arginine decarboxylase (ADC) and ornithine decarboxylase (ODC) were accumulated in the G₁ phase than those in the control, while the treatment with an inhibitor of spermidine (SPD) synthase showed no effect on the distribution of cells. The endogenous levels of the PAs, putrescine (PUT), SPD, and spermine (SPM), were determined during the cell cycle in synchronous cultures of C. roseus. Two peaks of endogenous level of PAs, in particular, of PUT and SPD, were observed during the cell cycle. Levels of PAs increased markedly prior to synthesis of DNA in the S phase and prior to cytokinesis. Activities of ADC and ODC were also assayed during the cell cycle. Activities of ADC was much higher than that of ODC throughout the cell cycle, but both activities of ODC and ADC changed in concert with changes in levels of PAs. Therefore, it is suggested that these enzymes may regulate PA levels during the cell cycle. These results indicate that inhibitors of PUT biosynthesis caused the suppression of cell proliferation by prevention of the progression of the cell cycle, probably from the G₁ to the S phase, and PUT may play more important roles in the progression of the cell cycle than other PAs.     

Spermidine,a sensor for antizyme 1 expression regulates intracellular polyamine homeostasis

Although intracellular polyamine levels are highly regulated, it is unclear whether intracellular putrescine (PUT), spermidine (SPD), or spermine (SPM) levels act as a sensor to regulate their synthesis or uptake. Polyamines have been shown to induce AZ1 expression through a unique +1 frameshifting mechanism. However, under physiological conditions which particular polyamine induces AZ1, and thereby ODC activity, is unknown due to their inter-conversion. In this study we demonstrate that SPD regulates AZ1 expression under physiological conditions in IEC-6 cells. PUT and SPD showed potent induction of AZ1 within 4 h in serum-starved confluent cells grown in DMEM (control) medium. Unlike control cells, PUT failed to induce AZ1 in cells grown in DFMO containing medium; however, SPD caused a robust AZ1 induction in these cells. SPM showed very little effect on AZ1 expression in both the control and polyamine-depleted cells. Only SPD induced AZ1 when S-adenosylmethionine decarboxylase (SAMDC) and/or ODC were inhibited. Surprisingly, addition of DENSpm along with DFMO restored AZ1 induction by putrescine in polyamine-depleted cells suggesting that the increased SSAT activity in response to DENSpm converted SPM to SPD, leading to the expression of AZ1. This study shows that intracellular SPD levels controls AZ1 synthesis.     

Inhibitory and promotive effects of polyamines on transglutaminase-induced protein polymerization

Transglutaminase (TGase) has been reported to be involved in the regulation of cell growth. We examined the effects of polyamines on TGase activity. The polymerization of casein was inhibited by putrescine (PUT) and spermidine (SPD). On the other hand, polymerization of N,N-dimethylcasein was increased by spermine (SPM) and SPD. These results suggested polyamines played two distinct roles as inhibitor and promoter for TGase-catalyzed protein polymerization.     

Immunomodulatory action of spermine and spermidine on NR8383 macrophage line in various culture conditions

We examined the effect of spermine (SPM) and spermidine (SPD) on tumor necrosis factor (TNF)alpha and monocyte chemoattractant protein-1 (MCP-1) secretion from macrophages in various culture conditions, including several protocols of polyamines addition and media supplemented with 0, 1 or 15% fetal bovine serum. TNFalpha secretion was inhibited by SPM or SPD added 18h before stimulation in a concentration-dependent manner. Their effect was directly related to the presence of FBS. When SPM or SPD was added simultaneously to the stimulus, the TNFalpha secretion inhibition was higher than that obtained after pre-treatment. In this case, the effect was inversely proportional to the presence of FBS. The addition of polyamines also inhibited the secretion of MCP-1 in NR8383 cells. We conclude that SPM and SPD inhibited the secretion of inflammatory cytokines TNFalpha and MCP-1 in different ways, depending on culture conditions. In any case, SPM was more effective than SPD.     

Efficient plant regeneration from long-term callus cultures of rice by spermidine

A significant reduction in regeneration potential with increasing age (upto 12months) in rice (Oryza sativa L. cv.TN-1) embryogenic callus cultures was observed. Spermidine, while having an inhibitory effect on plant regeneration in fresh callus cultures, promoted morphogenesis in long-term callus cultures. A massive accumulation of polyamines, particularly putrescine (5-fold) was observed in 12 month old cultures resulting in a change of putrescine /spermidine ratio, which seems to be important for maintaining the morphogenetic response. Application of exogenous spermidine to 12 month old cultures showed increased levels of polyamines and restored the putrescine/spermidine ratio comparable to that found in freshly induced cultures, concomitantly, promoting the plant regeneration via somatic embryogenesis in long-term rice callus cultures.Abbreviations PA Polyamines - PCA Perchloric acid - PUT Putrescine - SPD Spermidine - SPM Spermine     

Amelioration in secretion of hyperthermostable and Ca2+ -independent alpha-amylase of Geobacillus thermoleovorans by some polyamines and their biosynthesis inhibitor methylglyoxal-bis-guanylhydrazone

AIM: Effect of polyamines and their biosynthesis inhibitors on the production of hyperthermostable and Ca2+ -independent alpha-amylase by Geobacillus thermoleovorans MTCC 4220. METHODS AND RESULTS: The alpha-amylase was produced in starch-yeast extract-tryptone (SYT) broth with different polyamines (PA) and polyamine biosynthesis inhibitors, methylglyoxal-bis-guanylhydrazone (MGBG) and cyclohexylammonium sulphate (CHA) at 70 degrees C. The bacterial pellets were obtained after growing G. thermoleovorans at different temperatures, and used in determining total PA. The cell-free culture filtrates were used in alpha-amylase assays. During growth, total polyamines in biomass increased till 2 h, and thereafter, decreased gradually. The total polyamine content was very high in the biomass cultivated at 55 degrees C when compared with that of higher temperatures. Enzyme titre enhanced up to 70 degrees C, and thereafter declined. Extracellular enzyme and protein levels declined in the presence of exogenously added PA. The intracellular enzyme titres, however, were higher in putrescine (put) and spermidine (spd) than in spermine (spm). Polyamine biosynthesis inhibitor, MGBG enhanced secretion of alpha-amylase in a laboratory fermentor as well as shake flasks, although CHA did not affect it. CONCLUSIONS: The intracellular accumulation of put in the presence of MGBG appeared to enhance synthesis and secretion of alpha-amylase. Extracellular enzyme and protein levels were low in the presence of exogenously added PA, but their intracellular levels, however, were higher in put and spd than in spm. SIGNIFICANCE AND IMPACT OF THE STUDY: A substantial increase in the synthesis and secretion of alpha-amylase was attained in G. thermoleovorans in the presence of polyamine biosynthesis inhibitor MGBG.     

UV-B radiation induces changes in polyamine metabolism in the red seaweed <Emphasis Type="Italic">Porphyra cinnamomea</Emphasis>

Early investigations on the productivity of intertidal seaweeds found that, unlike some seaweeds, members of the genus Porphyra, a Rhodophyte, could tolerate physical stressors such as ultraviolet-B radiation (UV-B) both during immersion and when exposed to air. Increased stress tolerance was thought to be due to an unknown mechanism that operated at the thylakoid level. As recent research has shown that polyamines (PAs), bound to the thylakoid membranes of chloroplasts, play a critical role in protecting the photosynthetic apparatus from high-light and UV damage in both higher plants and in unicellular algae, we investigated PA metabolism in Porphyra cinnamomea exposed to UV-B. Our results show that PA biosynthesis was significantly upregulated in P. cinnamomea in response to UV-B, with the greatest proportional increases being in bound soluble putrescine (PUT), which increased by over 200%, in bound soluble spermidine (SPD) and spermine (SPM) which both increased by more than 150% and in bound insoluble SPM which increased by more than 120%. As PAs can be synthesised from ornithine via ornithine decarboxylase (ODC) or from arginine via arginine decarboxylase (ADC) we investigated the pathway via which polyamines were synthesised in P. cinnamomea. While exposure to UV-B caused increases in the activities of both ADC and ODC, the increase in ADC activity was 10 fold greater than that of ODC, suggesting that the ADC pathway was the principle route by which PA levels increased in response to UV-B. Mechanisms of PA mediated UV-B protection are discussed.     

Infant formula supplemented with polyamines alters the intestinal microbiota in neonatal BALB/cOlaHsd mice

Polyamines play a critical role in the development of intestinal and immune systems during the infant breastfeeding period, but the effect of polyamines on the microbiota has not been reported. The aim of our study was to characterize the impact on the colonization pattern in neonatal BALB/cOlaHsd mice after supplementing an infant formula (IF) with a mixture of putrescine (PUT), spermidine (SPD) and spermine (SPM). A total of 48 pups (14 days old) were randomly assigned to 4-day intervention groups as follows: breast-fed (unweaned) pups (n=12); weaned pups (n=12) fed an infant formula (IF); weaned pups (n=12) fed an IF enriched with a low concentration of PUT, SPD and SPM (2.10, 22.05 and 38.00 μg/day, respectively); and weaned pups (n=12) fed with IF enriched with a high concentration of PUT, SPD and SPM (8.40, 88.20 and 152.00 μg/day, respectively) of polyamines in accordance with normal proportions found in human milk. Microbiota composition was analyzed by fluorescent in situ hybridization (FISH) with flow cytometry detection. Microbiota changes in formula-fed mice were significantly greater following supplementation with polyamines (P<.01). Bifidobacterium group bacteria, Akkermansia-like bacteria and Lactobacillus–Enterococcus group levels were higher in the groups fed infant formula supplemented with polyamines, resulting in even higher numbers of bacteria than in the breastfed pups. Our findings indicate that infant formulas enriched with polyamines may interact with gut microbiota, suggesting that further studies in human infants are required to assess the impact of polyamines on both growth and microbiota levels.