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Stability of Bradyrhizobium japonicum Inoculants after Introduction into Soil 总被引:4,自引:3,他引:1
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Brigitte Brunel Jean-Claude Cleyet-Marel Philippe Normand Rene Bardin 《Applied microbiology》1988,54(11):2636-2642
Bradyrhizobium japonicum USDA 125-Sp, USDA 138, and USDA 138-Sm had been used as inoculants for soybean (Glycine max (L.) Merr.) in soils previously free of B. japonicum. At 8 to 13 years after their release, these strains were reisolated from soil samples. A total of 115 isolates were obtained through nodules, and seven colonies were obtained directly by a serological method. The stability of the inoculants was confirmed by comparing the reisolated cultures with their respective parental strains which had been preserved by being lyophilized or stored on a yeast extract-mannitol agar slant at 4°C. Comparisons were made on morphological and serological characters, carbon compound utilization (8 tested), intrinsic antibiotic resistance (9 tested), and enzymatic activity (19 tested). Mucous and nonmucous isolates of serogroup 125 were analyzed for symbiotic effectiveness and restriction fragment hybridization with a DNA probe. Our data suggest that the B. japonicum inoculants have survived for up to 13 years in the soils without significant mutation except for two reisolates with a slightly increased kanamycin resistance level. 相似文献
64.
Christophe N. N'soukpo-Kossi Jan Sielewiesiuk Roger M. Leblanc Richard A. Bone John T. Landrum 《生物化学与生物物理学报:生物膜》1988,940(2)
The linear dichroism of single monolayers of lutein, zeaxanthin and a mixture of lutein and synthetic phosphatidylcholine has been measured. The angle of orientation of the carotenoid molecules was found to lie between 45° and 51° relative to the plane of the solid support. Although the adsorbed monolayers were mostly in a monomeric state, microscopic observations, as well as the II-A isotherms, indicated the existence of crystalline islets. The results have been interpreted in connection with Haidinger's polarization brushes. 相似文献
65.
It has recently been suggested that topoisomerases could be important targets for drugs used in several diseases. This prompted us to purify and characterize the topoisomerases I and II present in the erythrocytes of protozoan parasites of the genus Plasmodium, the causative agent of malaria, in order to later use these enzymatic systems in antimalarial drug assays. The topoisomerases were purified from Plasmodium berghei, a parasite of mouse red cells. The Plasmodium topoisomerase II consists of two subunits with a molecular weight of about 160K. The enzyme is ATP- and Mg2+-dependent. The conditions for the reactions of relaxation, unknotting, decatenation, and catenation were found to be similar to those observed with enzymes from other eukaryotic cells. The Plasmodium topoisomerase I is a monomeric enzyme with a Mr of 70K-100K. It is ATP-independent and K+- or Na-dependent. Mg2+ is not required for relaxation but stimulates the reaction. Topoisomerase II was more sensitive to drug action than topoisomerase I. The most active drugs were the ellipticine derivatives. The antimalarial drugs, currently used in human clinical therapy, were poor inhibitors. Some antitumoral drugs stimulated the double-stranded DNA cleavage activity of Plasmodium topoisomerase II, like that of mammalian topoisomerases II. Antimalarial drugs had no stimulating activity. It is therefore suggested that Plasmodium topoisomerases are not good targets for antimalarial drugs. 相似文献
66.
Philippe Szankasi Christof Gysler Ulrich Zehntner Urs Leupold Jürg Kohli Peter Munz 《Molecular & general genetics : MGG》1986,202(3):394-402
Summary Recombination between dispersed yet related serine tRNA genes of Schizosaccharomyces pombe does occur during mitosis but it is approximately three orders of magnitude less frequent than in meiosis. Two mitotic events have been studied in detail. In the first, a sequence of at least 18 nucleotides has been transferred from the donor sup3 gene on the right arm of chromosome I to the related acceptor gene sup12 on the left arm of the same chromosome, thereby leading to the simultaneous change of 8 bp in the acceptor gene. This event must be explained in terms of recombination rather than mutation. It is assumed that it represents mitotic gene conversion, although it was not possible to demonstrate that the donor gene had emerged unchanged from the event. The second case reflects an interaction between sup9 on chromosome III and sup3 on chromosome I. Genetic and physical analysis allows this event to be described as mitotic gene conversion associated with crossingover. The result of this event is a reciprocal translocation. No further chromosomal aberrations were found among an additional 700 potential intergenic convertants tested. Thus intergenic conversion is much less frequently associated with crossingover than allelic conversion. However, the rare intergenic conversion events associated with crossingover provide a molecular mechanism for chromosomal rearrangements. 相似文献
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Claude Vallet-Strouve Charles Tellier Serge Poignant Philippe Boucrot 《The Journal of membrane biology》1985,84(1):73-79
Summary The effect of biliary salts and fatty acids on the bilayer structure of rabbit intestinal brush-border membranes was studied using the nonperturbing probe31P NMR. The broad. asymmetric lineshape of the31P NMR spectrum of isolated brush-border vesicles demostrates that their component phospholipids are organized in extended bilayers. These membranes are not significantly perturbed by incubation with physiological concentrations of biliary salts (3, 9, 18mm), demonstrating that the vesicles are highly stable, corresponding to their biological function. However, the emergence of a narrow peak superimposed on the broad lineshape indicates that a small proportion of the membrane phospholipids has reached isotropic motion, which may correspond to external or internal micellar structures. Incubation with mixed micelles of fatty acids and taurochlorate show that long-chain fatty acids enhance the membrane-perturbing effect of taurocholate while short-chain, watersoluble fatty acids do not, suggesting a difference in the absorption mechanisms. 相似文献
69.
Dr. Michel Jangoux Philippe Dubois Anne Lambert Catherine Yourassowsky 《Cell and tissue research》1985,242(3):657-660
Summary A microcanalicular network is demonstrated within the ossicle stroma and the dermal tissue of two asteroid species. Microcanaliculi are presumed to be mesodermal structures. They consist of convoluted tubular ducts lined by epithelial cells associated with scattered basiepithelial nervous processes. Such a microcanalicular system has not been reported previously from any echinoderm species. Its discovery in asteroids entails some conceptual changes, especially considering the physiology of the body wall.Research assistants of the National Fund for Scientific Research (NFSR, Belgium) 相似文献