Mixture Of Antagonists Research Articles

Induction of systemic resistance by mixtures of antagonist bacteria for the management of crown rot complex on banana

Among nine native bacterial strains isolated from banana fruit surface and rhizosphere and six bacterial strains introduced from the culture collection, three native strains viz., non-fluorescent Pseudomonas (NFP6), Pseudomonas fluorescens (Pf3a), and Bacillus subtilis (BS1); and two bacterial strains from culture collection viz., Azospirillum (AS1) and Azotobacter (AZ1) have recorded maximum inhibition of mycelial growth of crown rot pathogens (Lasiodiplodia theobromae and Colletotrichum musae) under in vitro condition. When these effective bacterial strains were treated on banana fruits under in vivo, significant reduction of crown rot disease and increased shelf life of banana was observed. However, bacterial strains applied as three way combinations (NFP6 + Pf3a + BS1) had greater effect compared with individual and two way combination of bacterial antagonist treatments. The effect of crown rot disease reduction was also comparable to that of fungicide Benomyl (0.1%) both under cold and room temperature storage conditions. Besides, the induction of defense-related enzymes such as phenylalanine ammonia-lyase (PAL), peroxidase (PO), polyphenoloxidase (PPO), and the accumulation of phenolics in banana fruit due to the application of bacterial antagonists were also studied at five different time intervals viz. 0th, 1st, 3rd, 5th and 7th days after treatment. When banana fruits treated with bacterial antagonists (individually and also in different combinations) and challenge-inoculated with crown rot pathogens, up to fourfold increase in defense-related enzymes and 3.6 fold increase in phenolic content was observed compared with control. The activity of these defense-related enzymes and phenolic content had gradually increased from 1st day after treatment to 3rd after treatment and reached their peak on 5th day after treatment. Among the bacterial antagonists which have been applied individually and in different combinations, the banana fruits treated with three-way antagonist mixture, i.e., NFP6 + Pf3a + BS1 recorded maximum induction of defense-related enzymes and accumulation of phenolics compared with individual and two-way combination of antagonist mixtures. This study suggest that the increased induction of defense-related enzymes and phenolic content due to the treatment of banana fruits with bacterial antagonists might have involved in the reduction of crown rot severity and in turn increased the shelf life of banana fruits.

The Efficiency of <i>Trichoderma harzianum</i> and <i>Aneurinobacillus migulanus</i> in the Control of Gladiolus Corm Rot in Soil-Less Culture System

Problem statement: Gladiolus is cultivated commonly for cut flower production, frequently as a protected crop. The glasshouse or polytunnel environment, providing excellent conditions for flower production, also make conditions more favorable for disease to develop. Approach: The pathogen Fusarium oxysporum f. sp. gladioli causes wilt diseases in a wide range of economically important plants and can have devastating effects on crop production. Trichoderma harzianum and Aneurinobacillus migulanus were tested separately and in combination for controlling F. oxysporum f. sp. gladioli activity in soilless culture using Perlite as the substrate. Results: The efficiency of both of antagonists against corm rot was evaluated based on vegetative and root growth parameters and on flowering parameters. T. harzianum was more effective than A. migulanus in disease suppression and also enhanced plant growth, increased flower production and quality. A. migulanus enhanced plant growth when tested alone. The mixture of antagonists reduced the efficiency of T. harzianum. Numbers of T. harzianum CFU in the substrate and on corms increased following application compared with treating with both antagonists. No T. harzianum was detected in the substrate by 120 day after planting, however, A. migulanus CFU significantly decreased on corms when inoculated in combination with T. harzianum and F. oxysporum f. sp. gladioli. However, A. migulanus CFU was not detected in the substrate of the same combination. SEM and Glasshouse results suggested that suppressive mechanisms of T. harzianum and A. migulanus differed. T. harzianum appeared to operate through a combination of antibiosis and substrate competition, whereas A. migulanus produced an electron-dense substance which may have inhibited the penetration of host tissues by F. oxysporum f. sp. gladiolus. Greater growth of T. harzianum was observed when inoculated alone or with F. oxysporum f. sp. gladioli hyphae. Conclusion: It was concluded that T. harzianum provided a more efficient and effective control of F. oxysporum f. sp. gladioli corm rot of Gladiolus when inoculated without A. migulanus.

Induction patterns of new CYP1 genes in environmentally exposed rainbow trout

The cytochrome P4501 ( CYP1) gene family comprises four subfamilies in fish: CYP1A, CYP1B, CYP1C, and CYP1D. Only two CYP1 genes, CYP1A1 and CYP1A3, are so far known in rainbow trout ( Oncorhynchus mykiss). The present study aimed to identify other CYP1 subfamily genes in rainbow trout, to establish methods for quantitative mRNA expression analysis of these genes, and to determine their basal and induced mRNA expression in gills and liver. Another goal was to examine their mRNA expression in environmentally exposed fish. We cloned four new transcripts, denoted rbCYP1B1, rbCYP1C1, rbCYP1C2, and rbCYP1C3. Levels of these and the previously known rbCYP1A transcripts were determined by real-time PCR in unexposed fish, fish exposed to the potent aryl hydrocarbon receptor (AhR) agonist 3,3′,4,4′,5-pentachlorobiphenyl (PCB126), and fish caged in various waters in the Uppsala region (Sweden). The mRNA expression patterns observed in unexposed rainbow trout (basal levels) were markedly similar to those reported for orthologous genes in other species. All six transcripts were induced by PCB126 in gills and liver, suggesting all genes to be AhR regulated. The caged fish showed clear rbCYP1 induction in gills at all monitoring sites (up to 70-fold the basal level), whereas the liver responses were weak; induction (up to 5-fold) was recorded only at the Uppsala municipal sewage treatment plant outlet. Gill filament EROD activity was induced at all caging sites. Most interestingly, the rbCYP1 gene response patterns in gills differed among caging sites and among subfamilies. The EROD induction seemed to only reflect induction of rbCYP1A transcription. Response patterns of multiple CYP1 genes in gills and liver could provide an improved monitoring strategy. Such patterns could be used to characterize complex mixtures of AhR agonists and antagonists in aquatic environments.

Non-simultaneous ecotoxicity testing of single chemicals and their mixture results in erroneous conclusions about the joint action of the mixture

The ecotoxicity of binary chemical mixtures with a common mode of action is often predicted with the concentration addition model. The assumption of concentration addition is commonly tested statistically based on results of toxicity experiments with the two single chemicals and their binary mixture. The present simulation study shows that if not all these experiments are performed simultaneously, one has a 20–80% chance of concluding synergism or antagonism while the mixture is actually additive (false positive rate). Truly synergistic or antagonistic mixtures have a 10–50% chance of being falsely categorized as additive (false negative rate). Additionally, false positive rates decrease with increasing experimental error, while false negative rates increase with increasing experimental error. Based on these results, we put forward a number of recommendations for future mixture ecotoxicity evaluation.

Implications of Pathogenesis by Erwinia amylovora on Rosaceous Stigmas to Biological Control of Fire Blight

As a prerequisite to infection of flowers, Erwinia amylovora grows epiphytically on stigmas, which provide a conducive habitat for bacterial growth. Stigmas also support growth of several other bacterial genera, which allows for biological control of fire blight; although, in practice, it is very difficult to exclude E. amylovora completely from this habitat. We investigated the dynamics of growth suppression of E. amylovora by comparing the ability of virulent and avirulent strains of E. amylovora to compete with each other on stigmas of pear, apple, and blackberry, and to compete with a co-inoculated mixture of effective bacterial antagonists. When strains were inoculated individually, virulent E. amylovora strain Ea153N attained the highest population size on stigmas, with population sizes that were approximately double those of an avirulent hrpL mutant of Ea153 or the bacterial antagonists. In competition experiments, growth of the avirulent derivative was suppressed by the antagonist mixture to a greater extent than the virulent strain. Unexpectedly, the virulent strain enhanced the population size of the antagonist mixture. Similarly, a small dose of virulent Ea153N added to inoculum of an avirulent hrpL mutant of Ea153 significantly increased the population size of the avirulent strain. A pathogenesis-gene reporter strain, Ea153 dspE::gfp, was applied to flowers and a subset of the population expressed the green fluorescent protein while growing epiphytically on stigmas of apple. These results are consistent with the hypothesis that virulent E. amylovora modifies the epiphytic habitat presented by the stigma through a pathogenesis-related process, which increases host resources available to itself and, coincidentally, to nonpathogenic competitors. Over nine orchard trials, avirulent Ea153 hrpL significantly suppressed the incidence of fire blight four times compared with six for the antagonist mixture. The degree of biological control achievable with an avirulent strain of E. amylovora likely is limited by its inability to utilize the stigmatic habitat to the same degree as a virulent strain.

Glutamatergic Transmission Is Sustained at a Later Period of Development of Medial Nucleus of the Trapezoid Body–Lateral Superior Olive Synapses in Circling Mice

Synaptic transmission between the medial nucleus of the trapezoid body (MNTB) and the lateral superior olive (LSO) was investigated in circling mice, an animal model for inherited deafness, using the voltage-clamp technique. In postnatal day 9 (P9) approximately P11 homozygous (cir/cir) circling mice, perfusion with 10 microM DL-APV and 10 microM CNQX reduced the 10 min average of postsynaptic currents (PSCs) to 8.8 +/- 3.0% compared with controls (n = 6). In heterozygous (+/cir) mice in the same age range, the 10 min PSCs average was reduced to 87.5 +/- 3.7% compared with controls (n = 7). In P0 approximately P2 homozygous (cir/cir) and heterozygous (+/cir) mice, the 10 min PSCs averages were 11.0 +/- 2.6% (n = 9) and 84.1 +/- 4.6% (n = 11), respectively. The effects of a glutamate antagonist mixture were almost the same in single fiber stimulation of P9 approximately P11 mice, reducing mean PSCs to 5.2 +/- 3.1% (homozygous (cir/cir) mice, n = 8) and 78.3 +/- 4.3% (heterozygous (+/cir) mice, n = 12). Immunohistochemical study revealed that glycine receptor (GlyR) immunoreactivity in heterozygous (+/cir) mice was more prominent than in homozygous (cir/cir) mice, while immunoreactivities of NR1 and NR2A-type NMDAR of P16 homozygous (cir/cir) mice were more prominent than in heterozygous (+/cir) mice of the same age. No significant difference was found in the immunoreactivity of NR2B-type NMDAR. These results indicate that glutamatergic transmission is sustained at a later period of developing MNTB-LSO synapses in homozygous (cir/cir) mice.

Biological control of onion leaf blight disease by bulb and foliar application of powder formulation of antagonist mixture

Three antagonists: Pseudomonas fluorescens (Pf1), Bacillus subtilis and Trichoderma viride, were tested alone and in combination for suppression of onion leaf blight (Alternaria palandui) disease under glasshouse and field conditions. The average mean of disease reduction was 24.81% for single strains and 42.44% for mixtures. In addition to disease suppression, treatment with a mixture of antagonists promoted plant growth in terms of increased plant height and ultimately bulb yield. Though seed treatment of either single strain or strain mixtures alone could reduce the disease, subsequent application to root, leaves or soil further reduced the disease and enhanced the plant growth. The mixture consisting of Pseudomonas fluorescens Pf1 plus Bacillus subtilis plus Trichoderma viride was the most effective in reducing the disease and in promoting plant growth and bulb yield in greenhouse and field tests.

Reduced sickle erythrocyte dehydration in vivo by endothelin-1 receptor antagonists

Elevated plasma levels of cytokines such as endothelin-1 (ET-1) have been shown to be associated with sickle cell disease (SCD). However, the role of ET-1 in the pathophysiology of SCD is not entirely clear. I now show that treatment of SAD mice, a transgenic mouse model of SCD, with BQ-788 (0.33 mg.kg(-1).day(-1) intraperitoneally for 14 days), an ET-1 receptor B (ET(B)) antagonist, induced a significant decrease in Gardos channel activity (1.7 +/- 0.1 to 1.0 +/- 0.4 mmol.10(13) cell(-1).h(-1), n = 3, P = 0.019) and reduced the erythrocyte density profile by decreasing the mean density (D(50); n = 4, P = 0.012). These effects were not observed in mice treated with BQ-123, an ET-1 receptor A (ET(A)) antagonist. A mixture of both antagonists induced a similar change in density profile as with BQ-788 alone that was associated with an increase in mean cellular volume and a decrease in corpuscular hemoglobin concentration mean. I also observed in vitro effects of ET-1 on human sickle erythrocyte dehydration that was blocked by BQ-788 and a mixture of ET(B)/ET(A) antagonists but not by ET(A) antagonist alone. These results show that erythrocyte hydration status in vivo is mediated via activation of the ET(B) receptor, leading to Gardos channel modulation in SCD.

Control of blue mold of apple by combining controlled atmosphere, an antagonist mixture, and sodium bicarbonate

‘Golden Delicious’ apples were wound-inoculated with Penicillium expansum and treated with various combinations of sodium bicarbonate and two antagonists ( Metschnikowia pulcherrima, Cryptococcus laurentii), and then stored in air or controlled atmosphere (CA = 1.4 kPa O 2 and 3 kPa CO 2) for 2 or 4 months at 1 °C. The antagonists survived and their populations increased during both air and CA storage. The antagonists alone reduced blue mold but were more effective when combined. Sodium bicarbonate tended to reduce lesion size when used with these antagonist, either when they were used alone or combined. Storage under CA conditions also increased the effectiveness of both antagonist, when used alone or in combination. The only treatment that completely eliminated P. expansum-incited decay was the combination of the two antagonists and sodium bicarbonate on fruit stored under CA conditions. The proper combination of alternative control measures can provide commercially acceptable long-term control of fruit decay and could help reduce our dependency on fungicides.

Relationships between locomotor activation and alterations in brain temperature during selective blockade and stimulation of dopamine transmission

It is well known that the dopamine (DA) system plays an essential role in the organization and regulation of brain activational processes. Various environmental stimuli that induce locomotor activation also increase DA transmission, while DA antagonists decrease spontaneous locomotion. Our previous work supports close relationships between locomotor activation and brain and body temperature increases induced by salient environmental challenges or occurring during motivated behavior. While this correlation was also true for psychomotor stimulant drugs such as methamphetamine and MDMA, more complex relationships or even inverted correlations were found for other drugs that are known to increase DA transmission (i.e. heroin and cocaine). In the present study we examined brain, muscle and skin temperatures together with conventional locomotion during selective interruption of DA transmission induced by a mixture of D1 and D2 antagonists (SCH-23390 and eticlopride at 0.2 mg/kg, s.c.) and its selective activation by apomorphine (APO; 0.05 and 0.25 mg/kg, i.v.) in rats. While full DA receptor blockade decreased spontaneous locomotion, it significantly increased brain, muscle and skin temperatures, suggesting metabolic brain activation under conditions of vasodilatation (or weakening of normal vascular tone). In contrast, APO strongly decreased skin temperature but tended to decrease brain and muscle temperatures despite strong hyperlocomotion and stereotypy. The brain temperature response to APO was strongly dependent on basal brain temperature, with hypothermia at high basal temperatures and weak hyperthermia at low temperatures. While supporting the role of DA in locomotor activation, these data suggest more complex relationships between drug-induced alterations in DA transmission, behavioral activation and metabolic brain activation.

Inosine released after hypoxia activates hepatic glucose liberation through A3adenosine receptors

Inosine, an endogenous nucleoside, has recently been shown to exert potent effects on the immune, neural, and cardiovascular systems. This work addresses modulation of intermediary metabolism by inosine through adenosine receptors (ARs) in isolated rat hepatocytes. We conducted an in silico search in the GenBank and complete genomic sequence databases for additional adenosine/inosine receptors and for a feasible physiological role of inosine in homeostasis. Inosine stimulated glycogenolysis (approximately 40%, EC50 4.2 x 10(-9) M), gluconeogenesis (approximately 40%, EC50 7.8 x 10(-9) M), and ureagenesis (approximately 130%, EC50 7.0 x 10(-8) M) compared with basal values; these effects were blunted by the selective A3 AR antagonist 9-chloro-2-(2-furanyl)-5-[(phenylacetyl)amino][1,2,4]-triazolo[1,5-c]quinazoline (MRS 1220) but not by selective A1, A2A, and A2B AR antagonists. In addition, MRS 1220 antagonized inosine-induced transient increase (40%) in cytosolic Ca2+ and enhanced (90%) glycogen phosphorylase activity. Inosine-induced Ca2+ mobilization was desensitized by adenosine; in a reciprocal manner, inosine desensitized adenosine action. Inosine decreased the cAMP pool in hepatocytes when A1, A2A, and A2B AR were blocked by a mixture of selective antagonists. Inosine-promoted metabolic changes were unrelated to cAMP decrease but were Ca2+ dependent because they were absent in hepatocytes incubated in EGTA- or BAPTA-AM-supplemented Ca2+-free medium. After in silico analysis, no additional cognate adenosine/inosine receptors were found in human, mouse, and rat. In both perfused rat liver and isolated hepatocytes, hypoxia/reoxygenation produced an increase in inosine, adenosine, and glucose release; these actions were quantitatively greater in perfused rat liver than in isolated cells. Moreover, all of these effects were impaired by the antagonist MRS 1220. On the basis of results obtained, known higher extracellular inosine levels under ischemic conditions, and inosine's higher sensitivity for stimulating hepatic gluconeogenesis, it is suggested that, after tissular ischemia, inosine contributes to the maintenance of homeostasis by releasing glucose from the liver through stimulation of A3 ARs.

Dopamine D 1 and D 2 receptor contributions to L-DOPA-induced dyskinesia in the dopamine-depleted rat

Using a rat model of L-DOPA-induced dyskinesia (LID), the contributions of dopamine D 1 and D 2 receptors to axial, limb, and orolingual (ALO) abnormal involuntary movements (AIMs) elicited by L-DOPA were examined. Chronic L-DOPA-treated rats received the D 1 receptor antagonist SCH23390 (0.01, 0.1, and 1.0 mg/kg; ip), the D 2 receptor antagonist Eticlopride (0.01, 0.1, and 1.0 mg/kg; ip), a mixture of both antagonists (0.01, 0.1, 1.0 mg/kg each; ip), or vehicle 30 min prior to L-DOPA (6 mg/kg; ip) + Benserazide (15 mg/kg; ip). SCH23390 (0.1 and 1.0 mg/kg) significantly reduced axial and limb AIMs, while the same doses of Eticlopride significantly decreased axial, limb, and orolingual AIMs. Co-administration of SCH23390 + Eticlopride significantly reduced axial (0.01, 0.1 and 1.0 mg/kg), limb (0.1 and 1.0 mg/kg ), and orolingual (0.1 and 1.0 mg/kg) AIMs. These results indicate the importance of D 1 and D 2 receptors to LID and further validate the rat AIMs model.

Long-Term Plasticity Mediated by mGluR1 at a Retinal Reciprocal Synapse

The flow of information across the retina is controlled by reciprocal synapses between bipolar cell terminals and amacrine cells. However, the synaptic delays and properties of plasticity at these synapses are not known. Here we report that glutamate release from goldfish Mb-type bipolar cell terminals can trigger fast (delay of 2-3 ms) and transient GABA(A) IPSCs and a much slower and more sustained GABA(C) feedback. Synaptically released glutamate activated mGluR1 receptors on amacrine cells and, depending on the strength of presynaptic activity, potentiated subsequent feedback. This poststimulus enhancement of GABAergic feedback lasted for up to 10 min. This form of mGluR1-mediated long-term synaptic plasticity may provide retinal reciprocal synapses with adaptive capabilities.

Improving biocontrol using antagonist mixtures with heat and/or sodium bicarbonate to control postharvest decay of apple fruit

‘Golden Delicious’ apples were wound-inoculated with either Colletotrichum acutatumor Penicillium expansumand then treated with various combinations of heat (38 ◦ C) for 4 days, 2% sodium bicarbonate, and two biocontrol agents alone or combined. The fruit were stored for 4 months at 1 ◦ C and then at 20 ◦ C for 2 weeks. Either heat or the antagonists reduced decay caused by C. acutatum, but a combination of the two was required to completely eliminate decay caused by this pathogen in most cases. Sodium bicarbonate alone or in combination with the antagonists had little effect on C. acutatum. The antagonists alone reduced decay caused by P. expansum but tended to be more effective when combined. Sodium bicarbonate increased the effectiveness of decay control by each antagonist alone or in combination. All of the treatments that included heat virtually eliminated decay caused by this pathogen. The proper combination of alternative control measures can provide an effective strategy to reduce postharvest decay of apple fruit. Published by Elsevier B.V.

Temperature and Pomaceous Flower Age Related to Colonization byErwinia amylovoraand Antagonists

ABSTRACT Fire blight of apple and pear is initiated by epiphytic populations of Erwinia amylovora on flower stigmas. Predicting this disease and managing it with microbial antagonists depends on an understanding of bacterial colonization on stigmas. Detached 'Manchurian' crab apple flowers were inoculated with E. amylovora and subjected to a range of constant temperatures or various fluctuating temperature regimes. Results may have application to disease risk assessment systems such as the Cougarblight model, which now are based on in vitro growth of the pathogen. In other experiments, detached crab apple flowers and attached 'Gala' apple flowers were maintained at different temperatures for various periods before inoculation with E. amylovora or antagonists (Pseudomonas fluorescens strain A506 and Pantoea agglomerans strains C9-1 and E325). Maximum stigma age supporting bacterial multiplication decreased as temperature increased, and was reduced by pollination. Stigmas were receptive to bacteria at ages older than previously reported, probably due to less interference from indigenous organisms. The study revealed antagonist limitations that possibly affect field performance (e.g., the inability of strain A506 to grow on relatively old stigmas conducive to the pathogen). Such deficiencies could be overcome by selecting other antagonists or using antagonist mixtures in the orchard.

Effects of various hormones on the sexual maturity of European eel (Anguilla anguilla L.) females from farm and lakes.

Previously described and alternative methods of the induction of sexual maturation in the European eel were investigated. Weekly administrations of a gonadoliberin agonist (nnRH-A=D-Phe6-GnRH-Ea) did not induce statistically significant effect on the gonads of treated eels in none of the dosages used (0.1 microg and 10 microg/fish). Carp pituitary extract and carp pituitary extract together with a dopamine antagonist caused considerable external changes (increase in eye size) and significant gonadal development in two treatment groups: wild and cultivated stocks. The induction of the ovulation by double amount of CP and gonadoliberin agonist with dopamine antagonist mixture was not successful in a wild stock. Fertilisation of stripped eggs of farm eel was attempted unsuccessfully in, due to low egg quality. An advanced phase of the sexual maturation process could be induced in specimen infected by Anguillicola crassus indicating, that nematode infection is not a limiting factor in the artificial propagation of the European eel.

Evaluation of mycoparasites as biocontrol agents of Rosellinia root rot in cocoa

Abstract Rosellinia spp. cause substantial mortality of cocoa (Theobroma cacao), especially in acidic soils rich in organic matter (O.M.) and, reportedly, low available phosphate. Cultural and chemical control are relatively ineffective and a supplementary biocontrol strategy would be highly desirable. Our aim was the isolation and evaluation of promising mycoparasites against Rosellinia of cocoa. We isolated 45 mycoparasites using a baiting technique. Three of them and a commercial isolate were prioritized for further evaluation based on their broad hostrange and/or effectiveness in pot bioassays. Because Rosellinia is favored by the same soil factors as mycoparasites, we investigated the effect of soil pH (range 4–6), O.M. (6–12%), and phosphate (0– 1000 mg kg −1 ) on their interaction. In vitro, both pathogens and antagonists grew well on a wide range of phosphate (0– 9500 mg kg −1 ) and at various pH (3.0–10.0) levels. The pH optimum usually coincided with the soil of origin and the phosphate optimum depended on the phosphate source used. In pot bioassays using natural soils, mixtures of antagonists exhibited more control than single strains and mixtures were effective over a wider range of soil conditions. High O.M. favored the pathogen more than its biocontrol agents. Soil pH interacted with the treatments such that biocontrol was most efficient at higher pH values and with the highest mixtures of antagonists. The addition of phosphate enhanced plant growth but had little effect on biocontrol efficacy. We conclude that mixtures of mycoparasites should be field tested in combination with liming and removal of O.M.

Modulatory action of acetylcholine on striatal neurons: microiontophoretic study in awake, unrestrained rats.

Cholinergic interneurons innervate virtually all medium spiny striatal cells, but the relevance of this input in regulating the activity and afferent responsiveness of these cells remains unclear. Studies in anaesthetized animals and slice preparations have shown that iontophoretic acetylcholine (ACh) either weakly excites or inhibits striatal neurons. These differential responses may reflect cholinergic receptor heterogeneity but may be also related to the different activity states of recorded units and different afferent inputs specific in each preparation. Single-unit recording was combined with iontophoresis in awake, unrestrained rats to examine the effects of ACh and selective muscarinic (oxotremorine M or Oxo-M) and nicotinic agonists (nicotine or NIC) on dorsal and ventral striatal neurons. These effects were tested on naturally silent, spontaneously active and glutamate-stimulated units. We found that iontophoretic ACh primarily inhibited spontaneously active and glutamate-stimulated units; the direction of the ACh response, however, was dependent on the firing rate. The effects of ACh were generally mimicked by Oxo-M and, surprisingly, by NIC, which is known to excite units in most central structures, including striatal neurons in anaesthetized preparation. Given that NIC receptors are absent on striatal cells but located primarily on dopamine terminals, we assessed the effects of NIC after complete blockade of dopamine receptors induced by systemic administration of a mixture of D1 and D2 antagonists. During dopamine receptor blockade the number of NIC-induced inhibitions dramatically decreased and NIC had mainly excitatory effects on striatal neurons. Thus, our data suggest that under physiologically relevant conditions ACh acts as a state-dependent neuromodulator, and its action involves not only postsynaptic but also presynaptic cholinoreceptors located on dopamine- and glutamate-containing terminals.

Characterization of biocontrol activity of two yeast strains from Uruguay against blue mold of apple

In the present study, two yeast antagonists, Cryptococcus laurentii (strain 317) and Candida ciferrii (strain 283) isolated from the surface of healthy apples, controlled blue mold of apple caused by Penicillium expansum. Both antagonists reduced the incidence of blue mold by 80% at 25 °C. At 5 °C C. ciferrii (strain 283) maintained the efficacy of disease control, but C. laurentii (strain 317) only reduced disease incidence by 50%. Moreover C. ciferrii (strain 283) exhibited significant protection at lower concentrations than C. laurentii (strain 317). The population of both strains increased in wounds of apples at 25 and 5 °C, and both strains maintained viable over a period of 35 days at 5 °C. Nutrient competition into wounds appeared to be the principal mode of action of these antagonists. Nitrogen rather than carbon appeared to be the limiting factor to both the antagonists and the pathogen. Further research will explore commercial potential of these antagonists and the possibility of enhancing biocontrol efficacy by using mixtures of antagonists or addtives such as calcium chloride or deoxyglucose.

Sensitive pupil response of early-onset alzheimer’s patients to a dilute mixture of cholinergic antagonist and α-Adrenergic stimulant

To investigate possible differences in pupil dilation and light reflex in Alzheimer's disease patients that can be attributed to the age of onset of the disease, a statistical comparison was made of pupil dilation and light reflex among early- and late-onset Alzheimer's disease, Down syndrome, and patients with vascular dementia, and normal controls. The subjects included 53 probable Alzheimer's disease outpatients, including both early-onset type (AD: n=21) and late-onset type (SD: n=32). They were compared with normal controls (n=15), Down syndrome patients (DS: n=6), and patients with vascular dementia (VD: n=9). All subjects and controls were dark-eyed Japanese. Pupil dilation and light reflex were tested in 21 AD and 32 SD patients, and were compared with those in the control subjects; 6 DS and 9 VD patients. The measured maximum increase in pupil diameter after instilling a mixture of anticholinergic and α -adrenergic stimulating drugs (Midrin-P®), in one eye was significantly greater in AD and DS than in the controls. However, there was no difference among SD, VD, and controls, suggesting a stronger pupil response to these drugs in AD than in SD. Pupil movement in response to light became significantly smaller and faster after instillation of the drugs in Alzheimer's disease patients. The above findings may be useful for the early detection of Alzheimer's disease.