Free-branching poinsettia cultivars that produce numerous axillary shoots are essential for propagating desirable multi-flowered poinsettias (Euphorbia pulcherrima Wild. Klotz). For more than a ...decade, a biological agent has been suspected to cause free-branching in poinsettias. Attempts to identify the branching agent have failed. Isolation of the pathogen was accomplished using a living host and it was concluded that an unculturable phytoplasma is the cause of free-branching in poinsettias. This is the first reported example of a pathogenic phytoplasma as the causal agent of a desirable and economically important trait.
Oligonucleotide primers derived from sequences of the 16S rRNA gene (CMR16F1, CMR16R1, CMR16F2, and CMR16R2) and insertion element IS1121 of Clavibacter michiganensis subsp. sepedonicus (CMSIF1, ...CMSIR1, CMSIF2, and CMISR2) were used in nested PCR to detect the potato ring rot bacterium C. michiganensis subsp. sepedonicus. Nested PCR with primer pair CMSIF1-CMSIR1 followed by primer pair CMSIF2-CMSIR2 specifically detected C. michiganensis subsp. sepedonicus, while nested PCR with CMR16F1-CMR16R1 followed by CMR16F2-CMR16R2 detected C. michiganensis subsp. sepedonicus and the other C. michiganensis subspecies. In the latter case, C. michiganensis subsp. sepedonicus can be differentiated from the other subspecies by restriction fragment length polymorphism (RFLP) analyses of the nested PCR products (16S rDNA sequences). The nested PCR assays developed in this work allow ultrasensitive detection of very low titers of C. michiganensis subsp. sepedonicus which may be present in symptomless potato plants or tubers and which cannot be readily detected by direct PCR (single PCR amplification). RFLP analysis of PCR products provides for an unambiguous confirmation of the identity of C. michiganensis subsp. sepedonicus
A phylogenetic analysis by parsimony of 16S rRNA gene sequences (16S rDNA) revealed that species and subspecies of Clavibacter and Rathayibacter form a discrete monophyletic clade, paraphyletic to ...Corynebacterium species. Within the Clavibacter-Rathayibacter clade, four major phylogenetic groups (subclades) with a total of 10 distinct taxa were recognized: (I) species C. michiganensis; (II) species C. xyli; (III) species R. iranicus and R. tritici; and (IV) species R. rathayi. The first three groups form a monophyletic cluster, paraphyletic to R. rathayi. On the basis of the phylogeny inferred, reclassification of members of Clavibacter-Rathayibacter group is proposed. A system for classification of taxa in Clavibacter and Rathayibacter was developed based on restriction fragment length polymorphism (RFLP) analysis of the PCR-amplified 16S rDNA sequences. The groups delineated on the basis of RFLP patterns of 16S rDNA coincided well with the subclades delineated on the basis of phylogeny. In contrast to previous classification systems, which are based primarily on phenotypic properties and are laborious, the RFLP analyses allow for rapid differentiation among species and subspecies in the two genera
1 Molecular Plant Pathology Laboratory, Bldg 011A, Rm 252, BARC West, USDA, ARS, Beltsville, MD 20705, USA
2 Insect Biocontrol Laboratory, USDA, ARS, Beltsville, MD 20705, USA
3 Tel: +1 301 504 6024. ...Fax: +1 301 504 5449. e-mail: imlee{at}asrr.arsusda.gov
ABSTRACT
RFLP analyses of 16S rDNA nested PCR products from 34 phytoplasma strains with 17 restriction enzymes delineated distinct pattern types. Based on similarity coefficients derived from RFLP analyses, the 34 representative phytoplasma strains were differentiated into 14 major groups (termed 16Sr groups) and 32 sub-groups. The similarity coefficients of RFLP patterns between distinct groups were 90% or below. By including additional groups and sub-groups from which RFLP analyses were not performed but for which 16S rDNA sequence data were available to predict restriction sites, a total of 14 groups and 41 sub-groups were proposed. By combined RFLP analyses of 16S rRNA and ribosomal protein gene sequences, thus far, a total of 46 subgroups have been recognized. The phytoplasma 16Sr groups were consistent with the phylogenetic groups (subclades) defined by phylogenetic analysis of near-full-length 16S rRNA gene sequences, indicating that the RFLP-based groups are phylogenetically valid. The approach using RFLP analyses of PCR-amplified 16S rDNA (and ribosomal protein gene sequences) provides a simple, reliable and rapid means for differentiation and classification of unknown phytoplasmas.
Rationale
Dyskinesia affects the majority of levodopa-treated parkinsonian patients within 5–10 years of treatment with levodopa. Clinical and preclinical observations suggest that an increase in ...serotoninergic transmission can contribute to the appearance of dyskinesias. It is thus conceivable that a modulation of synaptic dopamine (DA) levels induced by the inhibition of serotonin (5-HT) release, as a consequence of 5-HT
1A
agonists administration, might alleviate dyskinesias.
Objective
Since 5-HT
1A
receptors are expressed in the subthalamic nucleus (STN), the aim of the present study was to assess the effect of the intrasubthalamic administration of sarizotan, a compound with full 5-HT
1A
agonist properties, on levodopa-induced dyskinesias in the 6-hydroxydopamine (6-OHDA) model of parkinsonism.
Materials and methods
Male Sprague–Dawley rats received a unilateral 6-OHDA administration in the nigrostriatal pathway. A test of apomorphine was performed to evaluate dopamine depletion. One week later, a cannula was implanted in the STN. Animals were treated with levodopa (6 mg/kg, i.p., twice at day) for 22 consecutive days. On day 23, several doses (1 ng, 10 ng, or 1 μg) of sarizotan were administered through the cannula to the STN. The higher doses of sarizotan effectively attenuated all levodopa-induced dyskinesias including axial, limb, and orolingual subtypes.
Conclusions
These results suggest that the STN is a target structure for the antidyskinetic action of sarizotan and indicate that drug-mediated modulation of STN activity may be an alternative option for the treatment of levodopa-induced dyskinesias in Parkinson’s disease.
Vilazodone has been reported to be an inhibitor of 5-hydoxytryptamine (5-HT) reuptake and a partial agonist at 5-HT1A receptors. Using 35SGTPgammaS binding in rat hippocampal tissue, vilazodone was ...demonstrated to have an intrinsic activity comparable to the 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT). Vilazodone (1-10 mg/kg p.o.) dose-dependently displaced in vivo 3HDASB (N,N-dimethyl-2-(2-amino-4-cyanophenylthio)benzylamine) binding from rat cortex and hippocampus, indicating that vilazodone occupies 5-HT transporters in vivo. Using in vivo microdialysis, vilazodone (10 mg/kg p.o.) was demonstrated to cause a 2-fold increase in extracellular 5-HT but no change in noradrenaline or dopamine levels in frontal cortex of freely moving rats. In contrast, administration of 8-OH-DPAT (0.3 mg/kg s.c.), either alone or in combination with a serotonin specific reuptake inhibitor (SSRI; paroxetine, 3 mg/kg p.o.), produced no increase in cortical 5-HT whilst increasing noradrenaline and dopamine 2 and 4 fold, respectively. A 2-fold increase in extracellular 5-HT levels (but no change in noradrenaline or dopamine levels) was observed after combination of the 5-HT(1A) receptor antagonist, N-2-4-(2-methoxyphenyl)-1-piperazinylethyl-N-(pyridinyl)cyclohexanecarboxamide) (WAY-100635; 0.3 mg/kg s.c.) and paroxetine (3 mg/kg p.o.). In summary, vilazodone behaved as a high efficacy partial agonist at the rat hippocampal 5-HT1A receptors in vitro and occupied 5-HT transporters in vivo. In vivo vilazodone induced a selective increase in extracellular levels of 5-HT in the rat frontal cortex. This profile was similar to that seen with a 5-HT1A receptor antagonist plus an SSRI but in contrast to 8-OH-DPAT either alone or in combination with paroxetine.
A series of compounds such as dual serotonin re-uptake inhibitor and 5-HT1A receptor agonist was found to increase central serotonin levels in rat brain to a greater extent than established ...antidepressants.
The dual serotonin (5-HT) re-uptake inhibitor and 5-HT1A receptor agonist vilazodone was found to increase central serotonin levels in rat brain. In the course of structural modifications of vilazodone 3-{4-4-(2-oxo-2H-1-benzopyran-6-yl)-1-piperazinyl-butyl}-1H-indole-5-carbonitrile 8i and its fluorine analogue 6-{4-4-(5-fluor-3-indolyl)-butyl-1-piperazinyl}-2H-1-benzopyran-2-one have been identified. These unsubstituted chromenones are equally potent at the 5-HT1A receptor and 5-HT transporter. The implementation of nitrogen functionalities in position 3 of the chromenones resulted in compounds acting as agonists at the 5-HT1A receptor and as 5-HT re-uptake inhibitors like vilazodone. Ex vivo 5-HT re-uptake inhibition and in vitro 5-HT agonism were determined in the PCA- and GTPγS-assay, respectively. The potential of these chromenones to increase central 5-HT levels was measured in microdialysis studies and especially the derivatives 3-{4-4-(3-amino-2-oxo-2H-chromen-6-yl)-piperazin-1-yl-butyl}-1H-indole-5-carbonitrile 8f, ethyl (6-{4-4-(5-cyano-1H-indol-3-yl)-butyl-piperazin-1-yl}-2-oxo-2H-chromen-3-yl)-carbamate 8h and N-(6-{4-4-(5-cyano-1H-indol-3-yl)-butyl-piperazin-1-yl}-2-oxo-2H-chromen-3-yl)-acetamide 8k give rise to rapid development of increased serotonin levels in rat brain cortex, lasting longer than 3h.
1. The pharmacological properties of the novel diarylacetamide kappa-opioid receptor agonist, EMD 61753, have been compared with those of ICI 197067 (a centrally-acting kappa agonist) and ICI 204448 ...(a peripherally-selective kappa agonist). 2. EMD 61753 binds with high affinity (IC50 5.6 nM) and selectivity (kappa:mu:delta:sigma binding ratio 1:536:125: > 1,786) to kappa-opioid receptors and is a full and potent (IC50 54.5 nM) agonist in an in vitro assay for kappa-opioid receptors (rabbit vas deferens preparation). 3. Systemically-applied 14C-EMD 61753 is found in high concentrations in the lungs, liver, adrenal glands and kidneys. Considerably less radioactivity is detected in the whole brain, and this radioactivity is concentrated in the region of the cerebral ventricles in the choroid plexuses. EMD 61753 penetrates only poorly into the CNS. 4. EMD 61753 was weakly effective in pharmacological tests of central activity. This compound reversed haloperidolol-induced DOPA accumulation in the nucleus accumbens of the rat only at a dose of 30 mg kg-1, s.c., (doses of 0.1, 1.0 and 10 mg kg-1, s.c., and 1.0, 10 and 100 mg kg-1, p.o., were inactive). Hexobarbitone-induced sleeping in mice was prolonged by EMD 61753 at threshold doses of 10 mg kg-1, s.c., and 100 mg kg-1, p.o., whereas the motor performance of rats in the rotarod test was impaired by EMD 61753 with an ID50 value of 453 mg kg-1, s.c. 5. EMD 61753 produced dose-dependent, naloxone-reversible antinociception in the mouse formalin test (1st phase ID50 1.9 mg kg-1, s.c., and 10.4 mg kg-1, p.o.; 2nd phase ID50 0.26 mg kg-1, s.c., and 3.5 mg kg-1, p.o.) and rodent abdominal constriction test (ID50 mouse 1.75 mg kg-1, s.c., and 8.4 mg kg-1, p.o.; ID50 rat 3.2 mg kg-1, s.c., and 250 mg kg-1, p.o.). EMD 61753 was inactive, or only weakly effective, in the rat pressure test under normalgesic conditions. After the induction of hyperalgesia with carrageenin, however, this compound elicited potent, dose-dependent (ID50 0.08 mg kg-1, s.c., and 6.9 mg kg-1, p.o., after remedial application, and 0.2 mg kg-1, s.c., and 3.1 mg kg-1, p.o., after prophylactic application) and naloxone-reversible antinociception. The antinociceptive action of systemically-applied (50 mg kg-1, p.o.) EMD 61753 in the hyperalgesic pressure test was completely inhibited by injection of the K-opioid antagonist norbinaltorphimine (100 Lg) into the inflamed tissue, a result which indicates that this opioid effect is mediated peripherally.6. Cutaneous plasma protein extravasation produced by antidromic electrical stimulation of the rat saphenous nerve was dose-dependently inhibited by systemically-applied EMD 61753 (ID13 values 3.7 mg kg-1, s.c., and 35.8 mg kg-1, p.o.), and this effect was completely antagonized by intraplantar application of norbinaltorphimine (50 microg). Extravasation elicited by the intraplantar application of substance P (10 microg) was not influenced by the administration of EMD 61753.7. EMD 61753 produced dose-dependent diuresis in non-hydrated rats at doses of and above 1.0 mg kg-1, s.c., and 10 mg kg-1, p.o., and in saline-loaded rats at doses of and above 10 mg kg-1, s.c.,and 30mgkg-1, p.o.8. The prostaglandin-mediated fall in mean arterial blood pressure elicited in anaesthetized rats by i.v.application of arachidonic acid was not inhibited by prior treatment with EMD 61753 (10mg kg-1,p.o.). Thus, a blockade of prostaglandin synthesis via inhibition of cyclo-oxygenase activity does not contribute to the in vivo effects of EMD 61753 and its metabolites.9 The present experiments therefore indicate that EMD 61753 is a potent, selective and orally-effective full ic-opioid receptor agonist which has a limited ability to penetrate the blood-brain barrier and elicit centrally-mediated sedation, putative aversion, diuresis, and antinociception. The inhibitory actions of systemically-applied EMD 61753 against hyperalgesic pressure nociception and neurogenic inflammation are mediated peripherally, probably by opioid receptors on the endings of sensory nerve fibres.
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