Precursor Of Putrescine Research Articles

The development of a whole-cell biosensor enabled the identification of agmatine-producing Hafnia spp. in cheese

Agmatine, the decarboxylation product of arginine, is the precursor of putrescine - a harmful biogenic amine (BA) - that can accumulate in dairy products via bacterial metabolism involving the agmatine deiminase (AGDI) pathway. This first requires agmatine be produced via the decarboxylation of arginine and it remains unknown which microorganisms are responsible for this prior decarboxylation step.In addition, agmatine, as other BA, plays different physiological roles including those of co-transmitter and neuromodulator. Preclinical and clinical studies have shown agmatine to have a neuroprotective effect, rendering it of therapeutic interest being agmatine-producing bacteria proposed as psychobiotics.The identification of BA-producing microorganisms is based on the rise in pH due to the consumption of H+ during such decarboxylation reactions. However, in the detection of agmatine-producing microorganisms in cheese, this would lead to false positives since many bacteria possess arginine deiminase activity; this produces ornithine and ammonium from arginine, which also increases the pH. To overcome this problem, a whole-cell biosensor based on a previously developed agmatine-inducible transcription system was designed, and a protocol optimized for the successful identification of agmatine-producing microorganisms in cheese.The application of this protocol in cheese samples allowed for the isolation of agmatine-producing microorganisms identified as Hafnia spp. and unravels, for first time, the capacity of Hafnia paralvei to produce agmatine. This finding evidence the potential role of Hafnia spp. in putrescine accumulation in dairy products.

Impact of Gram-negative bacteria in interaction with a complex microbial consortium on biogenic amine content and sensory characteristics of an uncooked pressed cheese

The impact of Gram-negative bacteria on sensory characteristics and production of volatile compounds as well as biogenic amines (BA) in the core of an uncooked pressed type model cheese was investigated in the presence of a defined complex microbial consortium. Eleven strains of Gram-negative bacteria, selected on the basis of their biodiversity and in vitro BA-production ability, were individually tested in a model cheese. Four out of 6 strains of Enterobacteriaceae (Citrobacter freundii UCMA 4217, Klebsiella oxytoca 927, Hafnia alvei B16 and Proteus vulgaris UCMA 3780) reached counts close to 6log CFU g−1 in the model cheese. In core of cheeses inoculated with Gram-negative bacteria, only slight differences were observed for microbial counts (Enterococcus faecalis or Lactobacillus plantarum count differences below 1log CFU g−1), acetate concentration (differences below 200mgkg−1) and texture (greater firmness) in comparison to control cheeses. Cheese core colour, odour and volatile compound composition were not modified. Although ornithine, the precursor of putrescine, was present in all cheeses, putrescine was only detected in cheeses inoculated with H. alvei B16 and never exceeded 2.18mmolkg−1 cheese dry matter. Cadaverine was only detected in cheeses inoculated with H. alvei B16, K. oxytoca 927, Halomonas venusta 4C1A or Morganella morganii 3A2A but at lower concentrations (<1.05mmolkg−1 cheese dry matter), although lysine was available. Only insignificant amounts of the detrimental BA histamine and tyramine, as well as isopentylamine, tryptamine or phenylethylamine, were produced in the cheese model by any of the Gram-negative strains, including those which produced these BA at high levels in vitro.

Lack of Arginine Decarboxylase in Trypanosoma cruzi Epimastigotes

The presence of arginine decarboxylase (ADC) enzymatic activity in Trypanosoma cruzi epimastigotes is still a matter of controversy due to conflicting results published during the last few years. We have investigated whether arginine might indeed be a precursor of putrescine via agmatine in these parasites. We have shown that wild-type T. cruzi epimastigotes cultivated in a medium almost free of polyamines stopped their growth after several repeated passages of cultures in the same medium, and that neither arginine nor omithine were able to support or reinitiate parasite multiplication. In contrast, normal growth was quickly resumed after adding exogenous putrescine or spermidine. The in vivo labelling of parasites with radioactive arginine showed no conversion of this amino acid into agmatine, and attempts to detect ADC activity measured by the release of CO2 under different conditions in T. cruzi extracts gave negligible values for all strains assayed. The described data clearly indicate that wild-type T. cruzi epimastigotes lack ADC enzymatic activity.

Polyamines, auxins and organogenesis in leafy spurge ( Euphorbia esula L.)

Summary Canaline and canavanine (inhibitors of polyamine biosynthesis) effects on root and shoot formation were determined in vitro for etiolated hypocotyl segments of leafy spurge ( Euphorbia esula L.). Canaline (an ornithine analogue) at 10 to 100μmol/L inhibited root and shoot formation. The simultaneous application of putrescine did not reverse canaline-induced inhibition of root formation. Ornithine, a precursor of putrescine via the ornithine decarboxylase pathway, unexpectedly inhibited root formation. Canavanine (an arginine analogue) at 30 to 100μmol/L inhibited root and/or shoot formation. Inhibition of root formation by canavanine was not reversed by agmatine or putrescine, but was partially reversed by arginine. Indoleacetic acid (IAA) inhibited shoot formation, stimulated root formation, and partially reversed the inhibition of root formation by either canaline or canavanine. IAA generally increased endogenous levels of free polyamines in controls and canaline- or canavanine-treated tissues, but these changes were small and probably had little effect on organogenesis. IAA also partially reversed the inhibition of root (but not shoot) formation by arcaine and pentamidine, inhibitors of polyamine action in mammals. The roles of the polyamines in plants is not clear, but the polyamines may play only minor roles in root and shoot formation.

Could the loss of regulation of genetic expression in cancer cells be used to cause their necrosis?

In cancer cells the control over the genetic message involved in the induction of mitosis is irreversibly lost. This fact is indicated by certain phenomena displayed by cancer cells under restricted nutritional conditions. Cells transformed by DNA viruses (which stabilize “p53”) keep on cycling and die. In starving cells at the inside of tumors the synthesis of pre-rRNA still proceeds while all other anabolic processes are already at a standstill. The reason is that glutamine, glycine and aspartate are channelled into the enzymatic pathways for the synthesis of nucleosides: thus, proteinsynthesis is denied those aminoacids. Such situations might be imitated through the administration of excess nucleosides and (within limits) the simulataneous restriction of some selected aminoacids. DNA replication depends on the stabilization of p53, but an accumulation of pre-rRNA might occur, which ultimately might be harmful for cancer cells. Several ways to improve this rationale might be tested on cultured cells and on research animals. They include the destruction of methionine with bacterial enzymes, or the addition of ornithine, a precursor of putrescine, which is an important factor of DNA and pre-rRNA synthesis.

Biosynthetic arginine decarboxylase in Escherichia coli is synthesized as a precursor and located in the cell envelope.

The biosynthetic form of arginine decarboxylase (ADC) catalyzes the synthesis of agmatine, a precursor of putrescine, in Escherichia coli. Selective disruption of the cell envelope and an assessment of ADC activity or immunoprecipitable ADC in various fractions demonstrated its location between the cytoplasmic membrane and peptidoglycan layer. Expression in minicells of the speA gene encoding ADC resulted in the production of two immunoprecipitable species (74 and 70 kilodaltons). Studies in vivo with a pulse and chase of radiolabeled amino acid into the two species suggest a precursor-product relationship. This relationship was corroborated by demonstrating the accumulation of the 74-kilodalton species in a strain of E. coli unable to process signal sequences. Peptide mapping experiments with V8 protease, trypsin, and alpha-chymotrypsin demonstrated that the two species of ADC were very similar except for a minor difference. These data were used to substantiate the compartmentalization hypothesis as to how exogenous arginine can be channeled preferentially into putrescine.

Nicotiana glauca × Nicotiana langsdorffii tumor hybrid: growth, morphology, polyamines and nucleic acids in vitro

Callus of the tumor hybrid of Nicotiana glauca × N. langsdorffii grew better on agar in flasks than on liquid medium in flasks or on agar medium in Petri dishes. Asymmetric callus without roots produced small leaves and parenchyma cells were the most common type of cell. Few meristematic clusters were present, but these were very active during exponential and deceleration growth phases. The volume of their nucleoli, which were large and stained intensely, was used as a marker of the cell cycle. Shortly after transplantation the tissue divided synchronously, but thereafter it became asynchronous. An investigation of nucleic acids and polyamines showed that subcultures initiated a rapid synthesis and accumulation of DNA; thereafter the levels of tRNA and rRNA increased, especially in the deceleration phase, the amount of tRNA always being higher than rRNA. The polyamines putrescine and spermidine are always in larger amounts than in the normal tissue, and spermine could be detected in trace amounts. Their metabolism is correlated with arginine levels, the most important precursor of putrescine. Polyamine levels increased several fold during the deceleration phase, their increase being positively correlated with increased levels of nucleic acids, mainly during the very beginning of the subculture and, then during the deceleration phase.

Axonal transport of polyamines: A reappraisal

Axonal transport of putrescine and the polyamines in normal and transected motor axons of adult rat sciatic nerves was studied. [ 3H]Putrescine injected into the ventral horn region of the spinal cord was not transported distally along the course of the nerve as a function of time. l-[ 3H]ornithine, the immediate precursor of putrescine, when injected into the ventral horn of the spinal cord, was followed by rapid axonal transport of acid-insoluble material, but no transport of acid-soluble material, such as putrescine or the polyamines, was detected despite the demonstration that radioactive spermidine was synthesized at the site of the l-[ 3H]ornithine injection in the spinal cord. Furthermore, acid-soluble radioactive material failed to accumulate proximal to the site of a ligature of the sciatic nerve in acute and chronic experiments. Ligation of the sciatic nerve also failed to cause an accumulation of endogenous putrescine proximal to the ligature. The data showed no evidence for fast axonal transport of putrescine and the polyamines in normal and transected motor axons of the sciatic nerve in adult rats.

Products of L-[14C-carbamoyl] Citrulline Metabolism in Helianthus tuberosus Activated Tissue

Summary Activated tissues of Helianthus tuberosus tuber were fed with L-[ 14 C-carbamoyl] citrulline. Label could be detected in 14 CO 2 , N-carbamylputrescine (NCP) and arginine, indicating that citrulline may be a direct or indirect (via arginine) precursor of putrescine. Moreover the possibility exists of a further fate of citrulline, through conversion to arginine and then splitting via arginase and urease.

A biosynthetic ornithine decarboxylase in [formula omitted

Putrescine (1,4-diaminobutane) is found in E., coli , under a variety of growth conditions, at a level of approximately 15 micromoles per gram of wet weight. In spite of this relatively high intracellular concentration, very little is known about its biosynthesis. Tabor, Rosenthal and Tabor (1958) demonstrated the incorporation of 14C-ornithine into putrescine in intact E., coli , indicating that one of the late intermediates of the pathway of arginine biosynthesis is a precursor of putrescine. Gale (1940) demonstrated an induced ornithine decarboxylase in E., coli which catalyzed the formation of putrescine. However, since highly specialized culture conditions are required for the formation of this enzyme, it cannot be responsible for the large amounts of putrescine which are synthesized during growth in minimal medium. This induced ornithine decarboxylase probably serves a catabolic function. In this paper we report the presence of an ornithine decarboxylase in E., coli which appears to function in a biosynthetic rather than a catabolic capacity. This biosynthetic enzyme is distinct from the induced decarboxylase described by Gale, differing in its pH optimum, heat stability and conditions for formation.