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21.
Laurence BR 《Parasitology today (Personal ed.)》1986,2(3):77-79
Human activity, particularly migration and the export of live animals, can provide vehicles for the dispersal of many parasites and their vectors. These movements, often overlooked until too late, provide potential for epidemic outbreaks and can profoundly alter accepted ideas on the geographic distribution and epidemiological status of particular species. In this review, Brian Laurence discusses the recent rapid spread of blowflies into the americas; these conspicious green flies transport a variety of gastro-intestinal pathogens between their favoured environments of latrines and exposed food, and some species are important parasites of flesh wounds, causing cutaneous myiasis. 相似文献
22.
Laurence Marechal Pierre Guillemaut Jean-Michel Grienenberger Geneviève Jeannin Jacques-Henry Weil 《Plant molecular biology》1986,7(4):245-253
Summary Two bean mitochondria methionine transfer RNAs, purified by RPC-5 chromatography and two-dimensional gel electrophoresis, have been sequenced usingin vitro post-labeling techniques.One of these tRNAsMet has been identified by formylation using anE. coli enzyme as the mitochondrial tRNAF
Met. It displays strong structural homologies with prokaryotic and chloroplast tRNAF
Met sequences (70.1–83.1%) and with putative initiator tRNAm
Met genes described for wheat, maize andOenothera mitochondrial genomes (88.3–89.6%).The other tRNAMet, which is the mitochondrial elongator tRNAF
Met, shows a high degree of sequence homology (93.3–96%& with chloroplast tRNAm
Met, but a weak homology (40.7%) with a sequenced maize mitochondrial putative elongator tRNAm
Met gene.Bean mitochondrial tRNAF
Met and tRNAm
Met were hybridized to Southern blots of the mitochondrial genomes of wheat and maize, whose maps have been recently published (15, 22), in order to locate the position of their genes. 相似文献
23.
Laurence S. Kaminsky F.Peter Guengerich Ghazi A. Dannan Steven D. Aust 《Archives of biochemistry and biophysics》1983,225(1):398-404
R- and S-warfarin metabolite profiles (regio- and stereoselectivity) have been determined with hepatic microsomes from untreated rats and rats treated with nine individual polybrominated biphenyl (PBB) congeners, a commercial mixture of PBBs, and, for comparison with phenobarbital and 3-methylcholanthrene. The metabolic rates have been correlated with cytochrome P-450 (P-450) isozyme concentrations in the microsomes determined by immunochemical quantitation techniques (G. A. Dannan, F. P. Guengerich, L. S. Kaminsky, and S. D. Aust, (1983) J. Biol. Chem., 258, 1282–1288). The warfarin hydroxylase activities of the P-450 isozyme components of the various microsomal preparations (F. P. Guengerich, G. A. Dannan, S. T. Wright, M. V. Martin, and L. S. Kaminsky (1982) Biochemistry, 21, 6019–6030) were multiplied by the corresponding isozyme concentrations to obtain an assessment of the potential warfarin hydroxylase capacity of the microsomes, and the results were compared with actual activities. The results of these studies and comparisons indicate that substrate regio- and stereoselectivities of microsomal-bound P-450s are essentially retained on purification of the isozymes to homogeneity and reconstitution, that warfarin metabolism by microsomal preparations can be used to predict microsomal P-450 isozyme compositions, and that microsomal warfarin hydroxylase activity is greater than would be predicted based on the approx 20:1 ratio of P-450 to NADPH-P-450 reductase in the microsomes and on the known activities of constituent isozymes. Two P-450 isozymes which are induced by treatment of rats with phenobarbital appear to be more tightly linked to NADPH-P-450 reductase than does an isozyme induced by β-naphthoflavone. 相似文献
24.
A previous investigation of the structure of the extracellular polysaccharide gum from the nitrogen-fixing Rhizobium strain cb744 (a member of the slow-growing Cowpea group) indicated that there were two β-(1→4)-linked d-glucopyranosyl residues for each α-(1→4)-linked d-mannopyranosyl residue, and that each mannose was substituted at O-6 by a β-d-galactopyranosyl residue having 71% of the galactose present as 4-O-methylgalactose. The present study shows that, although the gum appeared to have a simple tetrasaccharide repeating unit, it is composed of two closely associated components. One is a (1→4)-linked α-d-mannan substituted at each O-6 by a β-d-galactopyranosyl residue (71% 4-O-methylated). The second component is a (1→4)-linked β-d-glucan. The existence of the two polysaccharides was established by separation of the β-d-galactosidase-treated gum on a column of concanavalin A-Sepharose 4B. The d configurations were determined and the anomeric attribution of the linkages confirmed by the use of enzymes. The interaction between the two gum components is discussed. 相似文献
25.
Field Laurence H. 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1974,92(4):415-441
Journal of Comparative Physiology A - 相似文献
26.
The total parasite load, helminths and arthropods, was measured in wild antelopes (Antilopinae and Alcelaphinae) in Kenya. Two parasite faunas were present, one consisting of endemic species and the other of species introduced into Africa with human livestock, presumably within the last 2000 years. There was little evidence of natural immunity to helminthic infection and gazelle restricted by ranching died of acute helminth infection. The helminth fauna of antelopes was dissimilar from that of zebra and giraffe which graze in the same savannah area, although species of tick were shared. New host records from Kenya are given for Bigalkenema curvispiculum Gibbons, Paracooperia raphicerci Ortlepp, Trichostrongylus axei Cobbold and T. colubriformis Giles from Gazella thomsonii Gilnther, B. curvispiculum from G. granti Brooke, Cooperia fulleborni Hung from Connochaetes taurinus Burchell and Moniezia expansa Rudolphi from Giraffa camelopardalis tippel-skirchi L. The implication of parasitic infection to conservation programmes and the possible future erosion of the conservation areas in East Africa is discussed briefly. 相似文献
27.
28.
J. Dennis Pollack Norman L. Somerson Laurence B. Senterfit 《Journal of bacteriology》1969,97(2):612-619
Mycoplasma pneumoniae harvested from media which had become acid lost the ability both to induce formation of tetrazolium reduction inhibition antibody and to act as antigens in immunodiffusion against human convalescent-phase sera. Incorporation of N-tris(hydroxymethyl)-2-aminoethane sulfonic acid and N-2-hydroxyethylpiperazine-N'-2-ethane sulfonic acid buffers into a new medium containing PPLO Serum Fraction instead of horse serum delayed the pH decline. Tris(hydroxymethyl)aminomethane, triethanolamine, and 3,6-endomethylene-1,2,3,6-tetrahydrophthalic acid buffers inhibited growth. Mycoplasmas obtained from buffered cultures retained antigenicity as measured by immunodiffusion and could stimulate tetrazolium reduction inhibition antibody formation in animals. 相似文献
29.
Measurement of the weight of individual virus particles from untreated and antibody-treated populations was made by quantitative electron microscopy. The weight of antibody bound depended on the concentration of antibody in solution. One population of viruses exposed to an antibody concentration which resulted in 95% inhibition of hemagglutination showed a mass increase of 55%, corresponding to an absolute increase of 9.0 x 10-17 g in the median value. Another population, whose hemagglutination inhibition assay was 64%, showed a 39% increase in mass corresponding to an absolute median increase of 7.3 x 10-17 g. The larger viruses in each population bound a greater absolute amount of antibody than did the smaller ones, but the latter bound relatively more antibody in proportion to their mass. No cross-reactivity was found between the antibody to influenza A/PR8 and the influenza strain B/LEE. Influenza A/PR8 controls exposed to nonspecific gamma-globulin displayed a significant weight loss, at least in part owing to loss from the core, as judged from the electron micrographs. 相似文献
30.