Co-existence of immunoreactivity to anti-dopamine,anti-serotonin and anti-vasotocin in the cerebral giant neuron of the pond snail Lymnaea stagnalis

Summary Consecutive sections of certain neurons in the central ganglia of the pond snail Lymnaea stagnalis appear to be immunoreactive to anti-dopamine and anti-serotonin. The Cerebral Giant Neurons stain in addition with antivasotocin. The observations indicate the presence of two biogenic amines within the same neuron and in addition their co-existence with a biologically active peptide.     

Partial Purification and Properties of Human Brain Aldehyde Dehydrogenases

Acetaldehyde and biogenic aldehydes were used as substrates to investigate the subcellular distribution of aldehyde dehydrogenase activity in autopsied human brain. With 10 microM acetaldehyde as substrate, over 50% of the total activity was found in the mitochondrial fraction and 38% was associated with the cytosol. However, with 4 microM 3,4-dihydroxyphenylacetaldehyde and 10 microM indoleacetaldehyde as substrates, 40-50% of the total activity was found in the soluble fraction, the mitochondrial fraction accounting for only 15-30% of the total activity. These data suggested the presence of distinct aldehyde dehydrogenase isozymes in the different compartments. The mitochondrial and cytosolic fractions were, therefore, subjected to salt fractionation and ion-exchange chromatography to purify further the isozymes present in both fractions. The kinetic data on the partially purified isozymes revealed the presence of a low Km isozyme in both the mitochondria and the cytosol, with Km values for acetaldehyde of 1.7 microM and 10.2 microM, respectively. However, the cytosolic isozyme exhibited lower Km values for the biogenic aldehydes. Both isozymes were activated by Mg2+ and Ca2+ in phosphate buffers (pH 7.4). Also, high Km isozymes were found in the mitochondria and in the microsomes.     

Biogenic Amine-Stimulated Cyclic Adenosine-3'',5''-Monophosphate Formation in the Rat Carotid Body

The subcutaneous injection of isoprenaline, salbutamol, histamine, and adrenaline to rats, which were subsequently killed by microwave irradiation, resulted in a rapid increase in the cyclic AMP content of the carotid body. On the other hand, noradrenaline, dopamine, adenosine, and 5-hydroxytryptamine, at doses at least 100 times greater than that of isoprenaline, did not significantly alter the cyclic nucleotide content in vivo. The response to isoprenaline was dose related, with an ED50 of 15 micrograms X kg-1, and reached a peak level 1-1.5 min after injection. Incubation of intact carotid bodies with isoprenaline (10(-5) M) in vitro also resulted in a 10-fold increase in cyclic AMP content. The in vivo response to isoprenaline could be blocked stereo-selectively by propranolol, and ICI 118.551, a beta 2-selective antagonist, blocks the isoprenaline-elicited increase in cyclic AMP completely at a dose of 30 micrograms X kg-1; whereas betaxolol, a beta 1-selective antagonist, was ineffective, even at a dose of 300 micrograms X kg-1. Hypoxia (5% oxygen in 95% N2) did not result in a significant increase in the cyclic AMP content, nor did it significantly alter the isoprenaline-stimulated increase in the cyclic AMP content of the rat carotid body. These results suggest that some catecholamines may stimulate cyclic AMP formation by interacting with a beta 2-adrenoceptor in the rat carotid body.     

In vitro investigation of α-amylase release from the digestive cells of the bivalve mollusc Pecten maximus: effect of second messengers and biogenic amines

The (neuro)endocrine control of enzyme release from invertebrate digestive cells remains poorly understood. A tissue dissociation procedure was developed to investigate the regulatory mechanisms of -amylase discharge from the cells of the stomach-digestive gland complex of the scallop Pecten maximus. The validity of the experimental system was tested by increasing the intracellular concentration of second messenger analogues (N ⁶,2-o-dibutyryl-adenosine-3,5 cyclic monophosphate and the ionophore A23187) known to mimic the activity of naturally occurring secretagogues in vertebrates: N ⁶,2-o-dibutyryl-adenosine-3,5 cyclic monophosphate increased the time and dose-dependent release of -amylase in a similar way as in vertebrates. A23187 was also very effective in inducing enzyme discharge. Since the in vitro bioassay was shown to be functional and because axon terminals were previously seen in close contact to -amylase secreting cells, the effect of some classic neurotransmitters was explored. Only the cholinergic agonist carbachol and dopamine evoked a secretory response. Maximal stimulation of -amylase release was reached at 10^-5 mol·l^-1 carbachol; at the same concentration dopamine was less effective than carbachol. By contrast, serotonin was totally inactive. The in vitro bioassay should prove useful for the identification of regulatory molecules involved in the control of enzyme discharge and to study stimulus secretion coupling mechanisms in scallop digestive cells.Abbreviations DBcAMP N ⁶, 2-O-dibutyryl-adenosine-3,5 cyclic monophosphate - cAMP adenosine-3,5 cyclic monophosphate     

Adrenergic control of hypothalamic function during osmotic stress in the mallard duck (Anas platyrhynchos)

Summary The role of the paraventricular nucleus (PVN) and biogenic amines (BA) in regulating the level of corticoids in the serum of osmotically stressed mallard ducks (Anas platyrhynchos) was analyzed employing three experimental approaches: 1) pharmacologic alteration of central BA levels, 2) microscopic evaluation of BA distribution, and 3) placement of electrolytic lesions into the PVN. Reserpine and -methyl-p-tyrosine (mpt), agents that decrease the amount of BA's in the central nervous system, produced a fivefold increase in the concentration of serum corticoids. Conversely, pargyline and amphetamine, agents that increase the functional pool of BA's, prevented the rise in serum corticoid concentration normally observed in birds challenged with an intraperitoneal injection of hypertonic saline. When the topographic distribution of BA's was analyzed in the brains of osmotically stressed and nonstressed ducks distinct changes in the intensity of catecholamine (CA) fluorescence were observed in only one location, the PVN of the hypothalamus. Additionally, electrolytic lesions stereotaxically placed in the PVN blocked the osmotic stress-induced rise in serum corticoid concentration. These data therefore indicate that the PVN in the mallard duck plays some role in regulating the observed stress-induced rise in serum corticoid concentration, and that this regulatory function is probably inhibited by catecholamines.This research was supported by research grant No. GB 33321 from the National Science Foundation. We wish to express our sincere thanks to Mr. Howard Funk, research director, Colorado Division of Wildlife, for the use of the State's animal facilitiesThis research was submitted as partial fulfillment for the degree of Doctor of Philosophy, Department of Physiology and Biophysics, Colorado State University, Ft. Collins, CO 80521     

Biomineralization of Poorly Crystalline Fe(III) Oxides by Dissimilatory Metal Reducing Bacteria (DMRB)

Dissimilatory metal reducing bacteria (DMRB) catalyze the reduction of Fe(III) to Fe(II) in anoxic soils, sediments, and groundwater. Two-line ferrihydrite is a bioavailable Fe(III) oxide form that is exploited by DMRB as a terminal electron acceptor. A wide variety of biomineralization products result from the interaction of DMRB with 2-line ferrihydrite. Here we describe the state of knowledge on the biotransformation of synthetic 2-line ferrihydrite by laboratory cultures of DMRB using select published data and new experimental results. A facultative DMRB is emphasized ( Shewanella putrefaciens ) upon which most of this work has been performed. Key factors controlling the identity of the secondary mineral suite are evaluated including medium composition, electron donor and acceptor concentrations, ferrihydrite aging/recrystallization status, sorbed ions, and co-associated crystalline Fe(III) oxides. It is shown that crystalline ferric (goethite, hematite, lepidocrocite), ferrous (siderite, vivianite), and mixed valence (magnetite, green rust) iron solids are formed in anoxic, circumneutral DMRB incubations. Some products are well rationalized based on thermodynamic considerations, but others appear to result from kinetic pathways driven by ions that inhibit interfacial electron transfer or the precipitation of select phases. The primary factor controlling the nature of the secondary mineral suite appears to be the Fe(II) supply rate and magnitude, and its surface reaction with the residual oxide and other sorbed ions. The common observation of end-product mineral mixtures that are not at global equilibrium indicates that microenvironments surrounding respiring DMRB cells or the reaction-path trajectory (over Eh-pH space) may influence the identity of the final biomineralization suite.     

The effects of lactic acid bacteria inoculants and formic acid on the formation of biogenic amines in grass silages

Silages were prepared in six laboratory experiments from four direct-cut grassland swards and pure swards of perennial ryegrass and false oat with dry matter contents ranging between 180 and 325?g/kg. Grass was fermented at 22°C and silages were stored at the same temperature for 4 months. Untreated silages (negative control) and silages preserved with 3?g/kg of formic acid (positive control) were compared with silages inoculated with commercial strains of Lactobacillus plantarum, Lactobacillus buchneri and a mixed preparation Microsil. The inoculants were applied at a dose of 5.10⁶ CFU/g of grass. Seven biogenic amines were extracted from silages with perchloric acid and determined as N-benzamides by micellar electrokinetic capillary chromatography. Common chemical quality parameters of silages were also determined. Tyramine, cadaverine and putrescine were the amines occurring at the highest concentration. As compared to untreated silages, formic acid was most effective to suppress formation of the main amines. Also the inoculants often decreased amine contents significantly (P?相似文献   

The effects of using lactic acid bacteria inoculants in maize silage on the formation of biogenic amines

Silages from five ripened varieties of silage maize with dry matter contents ranging between 275 and 410 g/kg were prepared in five laboratory experiments. Whole-plant maize was fermented at 22°C and silages were then stored at the same temperature for 4 months. Spontaneously fermented silages were prepared as control variants and compared with silages inoculated with commercial strains of Lactobacillus plantarum, Lactobacillus buchneri and a mixed preparation Microsil containing L. plantarum, Lactobacillus casei, Enterococcus faecium and Pediococcus pentosaceus. The starter cultures were applied at doses 5·10⁵ and 5·10⁶ CFU/g of chopped maize. Seven biogenic amines and polyamines were extracted from silages with perchloric acid and determined as N-benzamides by micellar electrokinetic capillary chromatography. Common chemical criteria of silage quality were also determined. All three inoculants, mainly at the higher dose, decreased significantly contents of tyramine, putrescine and cadaverine, three undesirable amines occurring at the highest levels. L. plantarum was the most effective. Contents of histamine and tryptamine were low in all experimental silages. Also relatively low were levels of polyamines spermidine and mainly of spermine.     

The Importance of Amine-degrading Enzymes on the Biogenic Amine Degradation in Fermented Foods: A review

Biogenic amines (BAs) are a class of harmful compounds often be found in high protein foods, especially naturally fermented foods. BAs derive from free amino acid decarboxylation through microbial activities and can cause toxic effects (headache, heart palpitations, vomiting) on humans, depending on individual sensitivity. Indigenous amine-degrading strains or strains producing amine-degrading enzymes (ADEs) have drawn great attention since they play an important role in affecting BA accumulation, and enzymes/genes involved in the biosynthetic mechanisms. They also help maintain the sensory quality of the final products. Besides, due to ADEs’ harmless catalytic products, they can be further utilized in fermented foods and beverages to reduce BAs. This review describes in detail the mechanisms of BAs formation, as well as the diversity of ADEs able to degrade BAs in a model or real food systems. A deeper knowledge of this issue is crucial because ADEs’ activities are often associated with strains rather than species or genera. Moreover, this information can help to improve the selection and characterization of strains for further applications as starters or bioprotective cultures, to obtain high-quality foods with reduced BAs contents.