Characterization of vascular postsynaptic NPY receptor function and regulation and differential sensitivity of Y1 and Y2 receptor function to changes in extracellular calcium availability and prior in vitro peptide exposure

Effects of calcium-free buffer, nifedipine, or prior cumulative neuropeptide Y (NPY) receptor agonist concentration exposure on vasoconstrictive responsiveness to the agonists were assessed in norepinephrine (NE)-conditioned isolated rat femoral artery rings. Calcium-free buffer and nifedipine partially inhibited responsiveness to initial NPY exposure; residual responsiveness to NPY re-exposure was unaffected. In contrast, these treatments markedly inhibited responsiveness to the Y2 agonist NPY13-36, the calcium channel agonist BAY K 8644 (BAY) and the partial alpha 1 adrenoceptor agonist indanidine but did not alter to the Y1 agonist [Leu31,Pro34]NPY. Responsiveness to NPY and NPY13-36 but not to BAY or indanidine was markedly reduced 120 min following conditioning regardless of prior ring exposure to the same peptide; only prior exposure reduced responsiveness to [Leu31,Pro34]NPY. Responsiveness changes to NPY at various times or after various numbers of NE and/or NPY exposures indicated that pre-exposure and time-related responsiveness reductions were discriminable and temporally unrelated to conditioning. Postsynaptic vascular Y2 receptor activation therefore accounts for the known sensitivity of NPY-induced pressor and vasoconstrictive actions to nifedipine. The 'time-dependent' loss of Y2 receptor function may also explain prior failures to observe postsynaptic arterial Y2 receptors in vitro.

Characterization of vascular postsynaptic neuropeptide Y receptor function and regulation. 1. NPY-induced constriction in isolated rat femoral artery rings is mediated by both Y1 and Y2 receptors: evidence from benextramine protection studies

Neuropeptide Y (NPY), a potent pressor agent and vasoconstrictor, is thought to contribute to the sympathetically mediated postsynaptic regulation of blood pressure primarily through activation of vascular Y1 rather than Y2 NPY receptors. However, data are available that conflict with this conclusion. In this article, the relative roles of postsynaptic Y1 and Y2 receptors as mediators of direct NPY-induced isolated rat femoral artery ring vasoconstriction were evaluated through use of selective Y1 and Y2 agonists, [Leu31, Pro34]NPY ([Leu, Pro]NPY) and NPY13-36 [NPY(13-36)], respectively, and the NPY receptor antagonist benextramine (BXT). NPY, [Leu, Pro]NPY and NPY(13-36) were equipotent as vasoconstrictors, and constriction induced by each peptide, but not by the calcium channel agonist BAY K 8644 (BAY), was almost completely blocked by 10 microM BXT. Each of the three peptides also induced self- and cross-desensitization and protection from BXT blockade, except that [Leu, Pro]NPY neither desensitized nor protected NPY(13-36)-associated responses. NPY also failed to protect [Leu, Pro]NPY- and NPY(13-36)-elicited constriction, and NPY(13-36) failed to provide self-protection, from BXT blockade. However, in these instances, as opposed to the [Leu, Pro]NPY-NPY(13-36) cross-protection experiments, the occurrence of protection was probably masked by the relatively large magnitude of desensitization concurrently induced by the protecting peptide. Taken together, the present findings suggest that NPY-induced rat femoral artery vasoconstriction is mediated by separate, BXT-sensitive, postsynaptic Y1 ([Leu, Pro]NPY-activated) and Y2 [NPY(13-36)-activated] receptors.

An Arabidopsis thaliana lipoxygenase gene can be induced by pathogens, abscisic acid, and methyl jasmonate

We isolated and characterized a 2.8-kb, full-length, Arabidopsis thaliana cDNA clone encoding a lipoxygenase. DNA sequence analysis showed that the deduced amino acid sequence of the Arabidopsis protein is 72 to 78% similar to that of legume seed lipoxygenases. DNA blot analysis indicated that Arabidopsis contains a single gene, LOX1, with appreciable homology to the cDNA clone. RNA blot analysis showed that the LOX1 gene is expressed in Arabidopsis leaves, roots, inflorescences, and young seedlings. LOX1 expression levels were highest in roots and young seedlings. In mature plants, LOX1 mRNA levels increased upon treatment with the stress-related hormones abscisic acid and methyl jasmonate and remained high for at least 96 h. Expression of the LOX1 gene was examined following infiltration of leaves with virulent (Psm ES4326) and avirulent (Pst MM1065) strains of Pseudomonas syringae. LOX1 mRNA levels were induced approximately 6-fold by both virulent and avirulent strains; however, the response to avirulent strains was much more rapid. Infiltration of leaves with Pst MM1065 resulted in maximal induction within 12 h, whereas maximal induction by Psm ES4326 did not occur until 48 h. When a cloned avr gene, avrRpt2, was transferred to Psm ES4326, LOX1 mRNA accumulated in a pattern similar to that observed for the avirulent strain Pst MM1065.

Synthesis of a phenyl beta-avobioside derivative of the disaccharide component of avoparcins

The synthesis of the phenyl beta-glycoside of avobiose, a disaccharide fragment present in the antibiotic avoparcin, is reported. It is based on glycosylation of phenyl 3,4,6-tri-O-benzyl-beta-D-glucopyranoside with 2,3,6-trideoxy-4-O-p-nitrobenzoyl-3-trifluoroacetamido-L-ribo-hex- 1-enitol, a fully protected glycal of L-ristosamine, in the presence of trimethylsilyl triflate.

[Isolation and identification of Leclercia adecarboxylate in clinical isolates in China]

1987, 3 strains of gram-negative straight rods were examined from 3 cases of patients with diarrhea. It's producing yellow pigment, fermentative metabolism of carbohydrates, oxidase test negative and motility with the help of peritrichous flagella. Through systematic biochemical identification, calculation of G+C mol% and homology of DNA/DNA, the species of Leclercia adecarboxylate are identified. While the susceptibility to certain antibiotics and the pathogenicity for white mice are tested, and relation of these microorganisms to clinical diarrhea is discussed.

[Homology study of leptospires by molecular hybridization]

Nick translation and random primer labelling method were applied to prepare three genomic DNA probes from Leptospira interrogans strain 017, Leptospira biflexa strain Patoc I and Leptonema illini strain 3055, and then hybridized with DNA of 17 strains leptospires from different genus, species, serogroup and serovar. The results showed no homology between Leptospira and Leptonema, and only a low degree of homology between L. interrogans and L. biflexa but it showed a high degree of homology among L. interrogans. The study also proved the possibility to establish a DNA probe prepared from a single leptospira strain to detect different serovars.

Induction of Arabidopsis defense genes by virulent and avirulent Pseudomonas syringae strains and by a cloned avirulence gene

We developed a model system to study the signal transduction pathways leading to the activation of Arabidopsis thaliana genes involved in the defense against pathogen attack. Here we describe the identification and characterization of virulent and avirulent Pseudomonas syringae strains that elicit disease or resistance symptoms when infiltrated into Arabidopsis leaves. The virulent and avirulent strains were characterized by determining growth of the pathogen in Arabidopsis leaves and by measuring accumulation of mRNA corresponding to Arabidopsis phenylalanine ammonia-lyase (PAL), beta-1,3-glucanase (BG), and chalcone synthase (CHS) genes in infected leaves. The virulent strain, P. syringae pv maculicola ES4326, multiplied 10(5)-fold in Arabidopsis leaves and strongly elicited BG1, BG2, and BG3 mRNA accumulation but had only a modest effect on PAL mRNA accumulation. In contrast, the avirulent strain, P. syringae pv tomato MM1065, multiplied less than 10-fold in leaves and had only a minimal effect on BG1, BG2, and BG3 mRNA accumulation, but it induced PAL mRNA accumulation. No accumulation of CHS mRNA was found with either ES4326 or MM1065. We also describe the cloning of a putative avirulence (avr) gene from the avirulent strain MM1065 that caused the virulent strain ES4326 to grow less well in leaves and to strongly elicit PAL but not BG1 and BG3 mRNA accumulation. These results suggest that the Arabidopsis PAL and BG genes may be activated by distinct signal transduction pathways and show that differences in plant gene induction by virulent and avirulent strains can be attributed to a cloned presumptive avr gene.

Synthesis of disaccharide fragments of dermatan sulfate

Condensation of crystalline methyl 2-azido-4,6-O-benzylidene-2-deoxy-beta-D-galactopyranoside with methyl (2,3,4-tri-O-acetyl-alpha-L-idopyranosyl bromide)uronate in dichloromethane, in the presence of silver triflate and molecular sieve, provided 54% of methyl 2-azido-4,6-O-benzylidene-2-deoxy-3-O-(methyl 2,3,4-tri-O-acetyl-alpha-L-idopyranosyluronate)-beta-D-galactopyranoside . The use of methyl (2,3,4-tri-O-acetyl-alpha-L-idopyranosyl trichloroacetimidate)uronate as glycosyl donor, in the presence of trimethylsilyl triflate, improved the yield to 68%. Regioselective opening of the benzylidene group with sodium cyanoborohydride followed successively by O-sulfation with the sulfur trioxide-trimethylamine complex, saponification, catalytic hydrogenolysis and selective N-acetylation gave the disodium salt of methyl 2-acetamido-2-deoxy-3-O-(alpha-L-idopyranosyluronic acid)-4-O-sulfo-beta-D-galactopyranoside. Condensation of methyl 2-azido-4,6-O-benzylidene-2-deoxy-beta-D-galactopyranoside with methyl (2,3,4-tri-O-acetyl-alpha-D-glucopyranosyl bromide)uronate in dichloromethane, in the presence of silver triflate and molecular sieve, gave methyl 2-azido-4,6-O-benzylidene-2-deoxy-3-O-(methyl 2,3,4-tri-O-acetyl-beta-D-glucopyranosyluronate)-beta-D-galactopryano side in 85% yield. The sequence already described then gave the disodium salt of methyl 2-acetamido-2-deoxy-3-O-(beta-D-glucopyranosyluronic acid)-4-O-sulfo-beta-D-galactopyranoside.

HPLC analysis of montanoa species for pharmacologically active constituents1

A reversed phase HPLC method was developed for the qualitative and quantitative analysis of selected biologically active diterpenoid constituents of methanolic and hot water extracts of some MONTANOA species.

Analysis of the individual regulatory components of the IncFII plasmid replication control system

Replication of the IncFII plasmid NR1 is controlled by regulating the amount of synthesis of the repA1 initiator protein at both the transcriptional and translational levels. We have examined mutations which have altered each of these levels of regulation, resulting in different plasmid copy numbers. The genes which encode each of the individual wild-type or mutant regulatory components from the replication control region of NR1 have been cloned independently into pBR322 vectors, and their effects in trans, either individually or in various combinations, on plasmid incompatibility, stability, copy number, and repA1 gene expression have been defined.

Regulation of transcription of the repA1 gene in the replication control region of IncFII plasmid NR1 by gene dosage of the repA2 transcription repressor protein

Transcription of the repA1 gene of the IncFII plasmid NR1 is initiated at two promoters in the replication control region. Transcription from the upstream promoter is constitutive at a low level, whereas transcription from the downstream promoter is regulated. The 5' end of the constitutively synthesized transcript also encodes the transcription repressor protein for the regulated downstream promoter. Therefore, the level of the repressor protein in the cell is gene dosage dependent. Using both lac gene fusions and quantitative hybridization methods, we have determined the in vivo relationship between the rate of transcription from the regulated promoter and the repressor protein concentration as a function of gene dosage. At the wild-type copy number of NR1, transcription from the regulated promoter is 96% repressed, but substantial derepression occurs when the copy number falls below the normal value. At or above the normal plasmid copy number, the basal level of repA1 mRNA is provided by transcription from the constitutive upstream promoter.

IncFII plasmid incompatibility product and its target are both RNA transcripts

The region of DNA coding for incompatibility (inc) and copy number control (cop) of the IncFII plasmid NR1 is transcribed in both the rightward and leftward directions. The rightward transcripts serve as mRNA for the repA1 protein, which is required for replication. A small, 91-base leftward transcript is synthesized from the opposite DNA strand and is complementary to a portion of the rightward mRNA near its 5' end. A 262-base-pair Sau3A restriction fragment that encodes the small leftward transcript, but does not include the rightward transcription promoters, was cloned into the vector pBR322 or pUC8. The same fragment was cloned from an Inc- mutant of NR1 that does not make the small leftward transcript. Transcription through the cloned fragments in these derivatives was under control of the tetracycline resistance gene in pBR322 or the lac promoter-operator in pUC8. In one orientation of the inserted DNA, a hybrid transcript containing rightward NR1 RNA sequences was synthesized. In the other orientation, a hybrid transcript containing leftward NR1 RNA sequences was synthesized. These plasmids were used to vary the intracellular levels of the rightward or leftward NR1 RNA transcripts and to test their effects in trans on various coresident derivatives of NR1. An excess of rightward NR1 RNA in trans stimulated expression of the essential repA1 gene and caused an increase in the copy number of a coresident NR1 plasmid. An excess of leftward NR1 RNA in trans inhibited the expression of the repA1 gene and lowered the coresident NR1 copy number, thereby causing incompatibility. A pBR322 derivative with no transcription through the cloned NR1 DNA had no effect in trans. These results suggest that the small leftward transcript is the incompatibility inhibitor of NR1 and that its target is the complementary portion of the rightward mRNA.