Avermectin
Mostrando 13-24 de 25 artigos, teses e dissertações.
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13. Avermectins, New Family of Potent Anthelmintic Agents: Efficacy of the B1a Component
When given to sheep as a single oral dose at 0.1 mg/kg, the B1a component of the avermectins caused a reduction of >95% in the numbers of Haemonchus contortus, Ostertagia circumcincta (including inhibited L4 larvae), Trichostrongylus axei, Trichostrongylus colubriformis, Cooperia oncophora, and Oesophagostomum columbianum. When given to cattle as a single or
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14. Photoaffinity labeling of avermectin binding sites from Caenorhabditis elegans and Drosophila melanogaster.
An azido-avermectin analog [4'' alpha-(4-azidosalicylamido-epsilon-caproylamido-beta-alan ylamido)-4''-deoxyavermectin B1a; azido-AVM] was synthesized and used to photoaffinity label avermectin binding sites present in the membranes of Caenorhabditis elegans and Drosophila melanogaster. Azido-AVM was biologically active and behaved like a competitive inhibit
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15. Microbial conversion of avermectins by Saccharopolyspora erythraea: glycosylation at C-4' and C-4''.
Avermectins and ivermectins are glycosylated at C-4'' and C-4' by both growing and resting cells of Saccharopolyspora erythraea. The reaction is catalyzed by a glycosyltransferase which is constitutive. The enzyme uses UDP-glucose as the glycosyl donor and avermectin or ivermectin mono- and disaccharides as acceptors. Avermectin and ivermectin aglycones and
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16. Deletion analysis of the avermectin biosynthetic genes of Streptomyces avermitilis by gene cluster displacement.
Streptomyces avermitilis produces a group of glycosylated, methylated macrocyclic lactones, the avermectins, which have potent anthelmintic activity. A homologous recombination strategy termed gene cluster displacement was used to construct Neor deletion strains with defined endpoints and to clone the corresponding complementary DNA encoding functions for av
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17. Cloning and Analysis of a DNA Fragment Stimulating Avermectin Production in Various Streptomyces avermitilis Strains
American Society for Microbiology.
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18. Avermectin B1a, a paralyzing anthelmintic that affects interneurons and inhibitory motoneurons in Ascaris.
Avermectin B1a (AVM) is an antiparasitic agent that paralyzes nematodes without causing hypercontraction or flaccid paralysis. Using selective stimulation techniques, we have shown that AVM blocks transmission between interneuron(s) and excitatory motorneurons in the ventral nerve cord of Ascaris. It also inhibits transmissin between inhibitory motoneurons a
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19. Transposon mutagenesis by Tn4560 and applications with avermectin-producing Streptomyces avermitilis.
The Tn3-like Streptomyces transposon Tn4560 was used to mutagenize Streptomyces avermitilis, the producer of anthelmintic avermectins and the cell growth inhibitor oligomycin. Tn4560 transposed in this strain from a temperature-sensitive plasmid to the chromosome and from the chromosome to a plasmid with an apparent frequency of about 10(-4) to 10(-3) at bot
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20. "Streptomyces avermitilis" mutants defective in methylation of avermectins.
"Streptomyces avermitilis" mutants defective in the methylation of the avermectins have been isolated and characterized. Four mutant strains, CR-1, CR-2, CR-3, and CR-4, were unable to methylate the oxygen at C5 of the macrolide moiety and produced essentially only the avermectin B components. These four strains lack avermectin B2 O-methyltransferase (B2OMT)
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21. A second branched-chain alpha-keto acid dehydrogenase gene cluster (bkdFGH) from Streptomyces avermitilis: its relationship to avermectin biosynthesis and the construction of a bkdF mutant suitable for the production of novel antiparasitic avermectins.
A second cluster of genes encoding the E1 alpha, E1 beta, and E2 subunits of branched-chain alpha-keto acid dehydrogenase (BCDH), bkdFGH, has been cloned and characterized from Streptomyces avermitilis, the soil microorganism which produces anthelmintic avermectins. Open reading frame 1 (ORF1) (bkdF, encoding E1 alpha), would encode a polypeptide of 44,394 D
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22. Avermectins, New Family of Potent Anthelmintic Agents: Producing Organism and Fermentation
The avermectins are a complex of chemically related agents which exhibit extraordinarily potent anthelmintic activity. They are produced by a novel species of actinomycete, NRRL 8165, which we have named Streptomyces avermitilis. The morphological and cultural characteristics which differentiate the producing organism from other species are described. The av
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23. Absence or pharmacological blocking of placental P-glycoprotein profoundly increases fetal drug exposure
It was recently shown that naturally occurring Mdr1a mutant fetuses of the CF-1 outbred mouse stock have no placental Mdr1a P-glycoprotein (P-gp) and that this absence is associated with increased sensitivity to avermectin, a teratogenic pesticide. To further define the role of placental drug-transporting P-gp in toxicological protection of the fetus, we use
American Society for Clinical Investigation.
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24. Functional Analysis of OleY l-Oleandrosyl 3-O-Methyltransferase of the Oleandomycin Biosynthetic Pathway in Streptomyces antibioticus
Oleandomycin, a macrolide antibiotic produced by Streptomyces antibioticus, contains two sugars attached to the aglycon: l-oleandrose and d-desosamine. oleY codes for a methyltransferase involved in the biosynthesis of l-oleandrose. This gene was overexpressed in Escherichia coli to form inclusion bodies and in Streptomyces lividans, producing a soluble prot
American Society for Microbiology.