Salt-sensitive and salt-tolerant barley varieties differ in the extent of potentiation of the ROS-induced K(+) efflux by polyamines.

Generation of high levels of polyamines and reactive oxygen species (ROS) is common under stress conditions. Our recent study on a salt-sensitive pea species revealed an interaction between natural polyamines and hydroxyl radicals in inducing non-selective conductance and stimulating Ca(2+)-ATPase pumps at the root plasma membrane (I. Zepeda-Jazo, A.M. Velarde-Buendía, R. Enríquez-Figueroa, B. Jayakumar, S. Shabala, J. Muñiz, I. Pottosin, Polyamines interact with hydroxyl radicals in activating Ca2+ and K+ transport across the root epidermal plasma membranes, Plant Phys. 157 (2011) 1-14). In this work, we extended that study to see if interaction between polyamines and ROS may determine the extent of genotypic variation in salinity tolerance. This work was conducted using barley genotypes contrasting in salinity tolerance. Similar to our findings in pea, application of hydroxyl radicals-generating Cu(2+)/ascorbate mixture induced transient Ca(2+) and K(+) fluxes in barley roots. Putrescine and spermine alone induced only transient Ca(2+) efflux and negligible K(+) flux. However, both putrescine and spermine strongly potentiated hydroxyl radicals-induced K(+) efflux and respective non-selective current. This synergistic effect was much more pronounced in a salt-sensitive cultivar Franklin as compared to a salt-tolerant TX9425. As retention of K(+) under salt stress is a key determinant of salinity tolerance in barley, we suggest that the alteration of cytosolic K(+) homeostasis, caused by interaction between polyamines and ROS, may have a substantial contribution to genetic variability in salt sensitivity in this species.

New insights into the role of spermine in Arabidopsis thaliana under long-term salt stress.

Polyamines (putrescine, spermidine and spermine) are traditionally implicated in the response of plants to environmental cues. Free spermine accumulation has been suggested as a particular feature of long-term salt stress, and in the model plant Arabidopsis thaliana the spermine synthase gene (AtSPMS) has been reported as inducible by abscisic acid (ABA) and acute salt stress treatments. With the aim to unravel the physiological role of free spermine during salinity, we analyzed polyamine metabolism in A. thaliana salt-hypersensitive sos mutants (salt overlay sensitive; sos1-1, sos2-1 and sos3-1), and studied the salt stress tolerance of the mutants in spermine and thermospermine synthesis (acl5-1, spms-1 and acl5-1/spms-1). Results presented here indicate that induction in polyamine metabolism is a SOS-independent response to salinity and is globally over-induced in a sensitive background. In addition, under long-term salinity, the mutants in the synthesis of spermine and thermospermine (acl5-1, spms-1 and double acl5-1/spms-1) accumulated more Na(+) and performed worst than WT in survival experiments. Therefore, support is given to a role for these higher polyamines in salt tolerance mechanisms.

Production of cachexia mediators by Walker 256 cells from ascitic tumors.

In neoplasic cachexia, chemical mediators seem to act as initiators or perpetuators of this process. Walker 256 cells, whose metabolic properties have so far been little studied with respect to cancer cachexia, are used as a model for the study of this syndrome. The main objective of this research was to pinpoint the substances secreted by these cells that may contribute to the progression of the cachectic state. Since inflammatory mediators seem to be involved in the manifestation of this syndrome, the in vitro production of nitric oxide (NO), cytokines (tumor necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6)), and prostaglandin E2 (PGE2) was evaluated in Walker 256 cells isolated from ascitic tumors. After 4 or 5 h, a significant increase in NO production was observed (2.55 +/- 1.56 and 4.05 +/- 1.99 nmol NO per 10(7) cells, respectively). When isolated from a 6-day-old tumor, a significantly lower production of IL-6 and higher production of TNF-alpha than in cells from a 4-day-old tumor were observed, indicating a relationship between the production of cytokines and the time of tumor development after implantation. Considerable production of PGE(2) by Walker 256 cells isolated from the 6-day-old tumor was also observed. Polyamines were also determined in Walker 256 cells. Levels of putrescine, spermidine, and spermine did not show significant differences in tumors developed during 4 or 6 days. Direct evidence of the release of proinflammatory cytokines and PGE2 by Walker 256 cells suggests that these mediators can drive the cachectic syndrome in the host, the effect being dependent on tumor development time.

L-arginine metabolism during interaction of Trypanosoma cruzi with host cells.

Trypanosoma cruzi invades a diversity of nucleated cells in the mammalian host. Macrophages are among the first cells to be parasitized and, after activation by inflammatory stimuli, they participate in the control of infection. However, some parasites manage to evade the immune response and establish a chronic infection in differentiated cells. L-arginine is located at the crossroads of divergent routes that produce metabolites, including nitric oxide and polyamines, which influence the outcome (i.e. resolution or progression) of infection. This article discusses the fate and actions of L-arginine-derived biomolecules formed both in the host and in the parasite during T. cruzi-host-cell interactions.

Effects of the porphyrinogenic compounds hexachlorobenzene and 3,5-diethoxycarbonyl-1,4-dihydrocollidine on polyamine metabolism.

The naturally occurring polyamines--putrescine, spermidine and spermine--are organic cations present in all living cells and essential for cell growth and differentiation. The aim of the present study was to extend the investigations on the effects of porphyrinogenic compounds on polyamine metabolism. This was achieved by studying putrescine, spermidine and spermine levels in a model of acute porphyria, i.e. 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-induced porphyria, and in a model of non-acute porphyria, i.e. hexachlorobenzene (HCB)-induced porphyria. HCB administration to female Wistar rats for 7, 14, 21, 28 and 56 days did not alter polyamine levels in liver, even though rats presented clear signs of HCB-induced porphyria. In contrast to HCB, DDC treatment resulted in a remarkable increase in putrescine levels in the liver of female and male Sprague-Dawley rats. This increase was due, at least in part, to ornithine decarboxylase (ODC) activation. DDC induction of putrescine levels did not show organ specificity, since it could also be seen in adrenal gland. Interestingly, the deregulation of polyamine biosynthesis occurred concomitantly with the deregulation of the heme biosynthetic pathway. In addition to porphyria, it is known that DDC intoxication affects several proteins of the hepatocyte cytoskeleton. It is suggested that DDC-induced increase in ODC activity and putrescine levels may be an early event contributing to alter the cytoskeleton.

Polyamine levels in testes and seminal vesicles from adult golden hamsters during gonadal regression-recrudescence.

The exposure of golden hamsters to short days results in early regression of the reproductive organs and subsequent spontaneous recrudescence characterized by active cellular regeneration and differentiation. Thus, adult male hamsters were subjected to short photoperiod (SP, 6L:18D) for 9, 12, 14, 16, 18, and 22 weeks or maintained under long photoperiod (LP, 14L:10D) for 22 weeks, to assess photoperiodic-related changes in testicular and seminal vesicle (SV) levels of polyamines (PA) that are involved in cell growth and differentiation. During the regression phase, the weights of the organs and the circulating levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin, testosterone, dihydrotestosterone, and 5 alpha-androstane-3 alpha, 17 beta-diol were significantly diminished and, thereafter, during the recrudescence phase, they recovered total or partially their control values. In both tissues, the exposure to SP for 14-16 weeks resulted in an increase of PA concentrations, followed by a return to control levels in the recrudescence period. At the time of maximal tissue involution, the ornithine decarboxylase (ODC) activity (key regulatory enzyme of PA biosynthesis) showed a significant increase in testis, preceding the sharp peak of PA concentration. However, a marked decrease in ODC activity was detected in SV. The concentration of N-acetyl PA in SV showed an increment at 16 weeks of SP, while no modifications were detected in testicular concentration. When PA, N-acetyl PA, and ODC activity were expressed per testis and per SV, values fell significantly during the involution period, but in the recrudescence phase levels were recovered concomitantly with the restoration of the organ weight and function. In conclusion, the photoperiodic-related changes in PA and their N-acetyl derivatives might play a crucial role in regrowth and differentiation of the male sexual organs during the spontaneous recrudescence phase. Additionally, organ-specific regulation of the PA biosynthesis pathway could also take place.

Polyamines in the male reproductive system.

This review covers some common aspects of the biosynthesis, interconversion pathways and biochemical functions of polyamines. A particular emphasis is given in experimental models as well as humans, to their presence in the male gonad, prostate gland, seminal vesicles, epididymis and semen. The interaction between hormones (androgens, LH, FSH and PRL) and the main enzymes involved on the polyamine biosynthesis, and the relationship of these compounds on cell growth and differentiation, are also discussed. In this regard, an attention is offered to the potential role of polyamines during early spermatogenesis stages and the use of some enzymes involved in their biosynthesis as sensitive and specific markers of the action of androgens and antiandrogens in the epididymis. Finally, a special issue is addressed to the controversial information documented on polyamines, their oxidation products and the relationship with male fertility.

Polyamines in the male reproductive system

This review covers some common aspects of the biosynthesis, interconversion pathways and biochemical functions of polyamines. A particular emphasis is given in experitemtal models as well as humans, to their presence in the male gonad, postate gland, seminal vesicles, epididymis and semen. The interaction between hormones (androgens, LH, FSH and PRL) and the main enzymes involved on the polymine biosynthesis, and the relationship of these compounds on cell growth and differentation, are also discussed. In this regard, an attention is offered to the potential role of polymines during early spermatogenesis stages and the use of some enzymed involved in their biosynthesis as sensitive and specific markers of the action of androgens and antiandrogens in the epididymis. Finally, a special issue is addressed to the controversial information documented on polymines, their oxidation products and the relationship with male fertility.

Polyamines in the male reproductive system

This review covers some common aspects of the biosynthesis, interconversion pathways and biochemical functions of polyamines. A particular emphasis is given in experitemtal models as well as humans, to their presence in the male gonad, postate gland, seminal vesicles, epididymis and semen. The interaction between hormones (androgens, LH, FSH and PRL) and the main enzymes involved on the polymine biosynthesis, and the relationship of these compounds on cell growth and differentation, are also discussed. In this regard, an attention is offered to the potential role of polymines during early spermatogenesis stages and the use of some enzymed involved in their biosynthesis as sensitive and specific markers of the action of androgens and antiandrogens in the epididymis. Finally, a special issue is addressed to the controversial information documented on polymines, their oxidation products and the relationship with male fertility. (AU)

Effects of 2,4-dichlorophenoxyacetic acid on polyamine transport and metabolism in Azospirillum brasilense Cd.

We had previously demonstrated that 1 mM 2,4-D inhibited cell growth, nucleic acid synthesis and protein synthesis (at the ribosomal level) of Azospirillum brasilense. These alterations were prevented by the presence of polyamines in the culture medium. On the other hand, polyamines did not affect the 2,4-D uptake. In this paper we demonstrate that 2,4-D alters the metabolism of polyamines and increases their uptake.

Putrescine decreases exploration of a black and white maze.

The effect of putrescine and cyclohexylamine on rat cortical polyamine concentration and on behavior in a black and white maze was studied. The levels of polyamines in brain cortex were determined 15 min, 2, 4, and 6 hours after injection of putrescine (200 or 400 mg/kg) or cyclohexylamine (380 mg/kg). Putrescine concentration increased 6-fold 15 min after injection of putrescine followed by a decline during the next 6 hours. Cyclohexylamine increased putrescine concentration doubling it 4 hours after injection. Spermidine and spermine concentrations did not change after either putrescine or cyclohexylamine injection. Behavior was studied in the Greek cross maze which provides the choice to enter either white or black compartments. Putrescine 200 mg/kg decreased entries into white but not black compartments, while putrescine 400 mg/kg decreased entries into both. The effect of cyclohexylamine was similar to putrescine 400 mg/kg. The behavioral effect of each treatment was independent of the time between injection and testing for up to 6 hours, while the levels of putrescine changed during the same period. Therefore, behavior was not directly related to total cortical putrescine.