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131.
Hermann Levy 《BMJ (Clinical research ed.)》1942,2(4254):82-83
132.
Stanley Levy 《Economic botany》1957,11(1):3-39
Like occasional other articles in Economic Botany, this one is little concerned with botany or plant utilization. Instead, it is a study in agricultural economics and social development in a part of the world where plant products, long produced under colonial management, have been significant items in development. 相似文献
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Invasion of Spores of the Arbuscular Mycorrhizal Fungus Gigaspora decipiens by Burkholderia spp. 总被引:1,自引:0,他引:1 下载免费PDF全文
Avram Levy Barbara J. Chang Lynette K. Abbott John Kuo Gerry Harnett Timothy J. J. Inglis 《Applied microbiology》2003,69(10):6250-6256
Burkholderia species are bacterial soil inhabitants that are capable of interacting with a variety of eukaryotes, in some cases occupying intracellular habitats. Pathogenic and nonpathogenic Burkholderia spp., including B. vietnamiensis, B. cepacia, and B. pseudomallei, were grown on germinating spores of the arbuscular mycorrhizal fungus Gigaspora decipiens. Spore lysis assays revealed that all Burkholderia spp. tested were able to colonize the interior of G. decipiens spores. Amplification of specific DNA sequences and transmission electron microscopy confirmed the intracellular presence of B. vietnamiensis. Twelve percent of all spores were invaded by B. vietnamiensis, with an average of 1.5 × 106 CFU recovered from individual infected spores. Of those spores inoculated with B. pseudomallei, 7% were invaded, with an average of 5.5 × 105 CFU recovered from individual infected spores. Scanning electron and fluorescence microscopy provided insights into the morphology of surfaces of spores and hyphae of G. decipiens and the attachment of bacteria. Burkholderia spp. colonized both hyphae and spores, attaching to surfaces in either an end-on or side-on fashion. Adherence of Burkholderia spp. to eukaryotic surfaces also involved the formation of numerous fibrillar structures. 相似文献
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Modifications of position 12 in parathyroid hormone and parathyroid hormone related protein: toward the design of highly potent antagonists 总被引:1,自引:0,他引:1
M Chorev M E Goldman R L McKee E Roubini J J Levy C T Gay J E Reagan J E Fisher L H Caporale E E Golub 《Biochemistry》1990,29(6):1580-1586
Truncated N-terminal fragments of parathyroid hormone (PTH), [Tyr34]bovine PTH(7-34)NH2, and parathyroid hormone related protein (PTHrP), PTHrP(7-34)NH2, inhibit [Nle8,18,[125I]iodo-Tyr34]-bPTH(1-34)NH2 binding and PTH-stimulated adenylate cyclase in bone and kidney assays. However, the receptor interactions of these peptides are 2-3 orders of magnitude weaker than those of their agonist counterparts. To produce an antagonist with increased receptor-binding affinity but lacking agonist-like properties, structure-function studies were undertaken. Glycine at position 12 (present in all homologues of PTH and in PTHrP), which is predicted in both hormones to participate in a beta-turn, was examined by substituting conformational reporters, such as D- or L-Ala, Pro, and alpha-aminoisobutyric acid (Aib), in both agonist and antagonist analogues. Except for N-substituted amino acids, which substantially diminished potency, substitutions were well tolerated, indicating that this site can accept a wide latitude of modifications. To augment receptor avidity, hydrophobic residues compatible with helical secondary structure were introduced. Incorporation of the nonnatural amino acids D-Trp, D-alpha-naphthylalanine (D-alpha-Nal), or D-beta-Nal into either [Tyr34]bPTH(7-34)NH2 or [Nle8,18,Tyr34]bPTH(7-34)NH2 resulted in antagonists that were about 10-fold more active than their respective 7-34 parent compound. Similarly, [D-Trp12]PTHrP(7-34)NH2 was 6 times more potent than the unsubstituted peptide but retained partial agonistic properties, although markedly reduced, similar to PTHrP(7-34)NH2. The antagonistic potentiating effect was configurationally specific.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
136.
Addi R. Fadel Dan Q. Jin Gaetano T. Montelione Ronald M. Levy 《Journal of biomolecular NMR》1995,6(2):221-226
Summary Order parameters for the backbone N–H and C–H bond vectors have been calculated from a 150 ps molecular dynamics (MD) simulation of human type- transforming growth factor in H2O solvent. Two kinds of crankshaft motions of the polypeptide backbone are observed in this MD trajectory. The first involves small-amplitude rocking of the rigid peptide bond due to correlated changes in the backbone dihedral angles i–1 and i. These high-frequency librational crankshaft motions are correlated with systematically smaller values of motional order parameters for backbone N–H bond vectors compared to C–H bond vectors. In addition, infrequent crankshaft flips of the peptide bond from one local minimum to another are observed for several amino acid residues. These MD simulations demonstrate that comparisons of N–H and C–H order parameters provide a useful approach for identifying crank-shaft librational motions in proteins. 相似文献
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