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C Toga-Piquet A S Henderson J M Grillo A M Vagner-Capodano A Stahl 《Comptes rendus de l'Académie des sciences. Série III, Sciences de la vie》1984,298(14):383-386
The Pig chromosomes that contain rDNA sites displayed a polymorphism in the distribution of the genes among the nucleolar organizers located on pairs Nos. 8 and 10. Two, or more often three, active sites were observed in the chromosomes of lymphocytes stimulated with phytohemagglutinin. Only 5% of the metaphases showed a 4th small active site. At the onset of stimulation most cells contained one-two nucleoli; four nucleoli were never observed. After prolonged stimulation, the number of nuclei containing three nucleoli increased. A 4th small nucleolus appeared in a few cells, presumably formed by activation of the smallest rDNA site. 相似文献
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Entamoeba histolytica: effect of growth conditions and bacterial associates on isoenzyme patterns and virulence 总被引:11,自引:0,他引:11
D Mirelman R Bracha A Chayen A Aust-Kettis L S Diamond 《Experimental parasitology》1986,62(1):142-148
In xenic culture, isolates of Entamoeba histolytica from asymptomatic carriers are characterized, with rare exception, by possession of a nonpathogenic zymodeme. During the process of axenizing such an isolate, strain CDC:0784:4, a change in the pattern of the isoenzymes from nonpathogenic zymodeme I to pathogenic zymodeme II was observed 40 days after the amebae had been transferred from a medium for xenic cultivation to one used for axenic cultivation, but before axenization of the amebae had actually occurred. Axenization was accomplished by feeding the amebae lethally irradiated bacteria while suppressing and finally eradicating with antibiotics the bacterial flora accompanying the amebae in the original xenic culture. The change in zymodeme was accompanied by a change in virulence as evidenced by the ability of the amebae to produce hepatic abscesses in hamsters and to destroy monolayers of tissue culture cells. Two explanations are offered for the observed changes in zymodeme and virulence: a zymodeme is not a stable inherent property of the ameba. Alternatively, the original isolate consisted of two zymodeme populations and the conditions of growth selected for one or the other of the populations. In either case, our results suggest that the finding of a particular zymodeme in a culture of E. histolytica isolated from an asymptomatic carrier of the parasite cannot be used to predict a clinical condition or serve as a basis for the recommendation of therapy. 相似文献
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Kirsten Skamstrup Hansen Stefan Vieths Helle Vestergaard Per Stahl Skov Carsten Bindslev-Jensen Lars K. Poulsen 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2001,756(1-2)
The aim of the study was to investigate the possibility of a seasonal variation in reactivity to apples in 27 birch pollen allergic patients. Before and during the birch pollen season 1998, the patients were subjected to double-blind, placebo-controlled food challenges (DBPCFCs) with grated fresh Golden Delicious apple followed by an open food challenge with whole fresh apple. The clinical reactions elicited during the challenges were evaluated both by the patients and the investigators. Moreover, the skin reactivity and the in vitro reactivity to apple were evaluated by skin prick test (SPT), leukocyte histamine release (HR), measurement of specific IgE, and immunoblotting experiments. The sensitivity of the DBPCFC, when compared with the result of the open challenge, was 0.74 (14/19) before the season and 0.80 (16/20) during the season. None of the patients reacted to the blinded challenge without a subsequent reaction to the open challenge. One placebo reaction was registered both before and in season, but not in the same patient. The patient scores of the first positive challenges, and the maximal scores of each combined blinded and open challenge session, were significantly increased during the pollen season (P<0.05). The scores of the open challenge were significantly higher than the scores of the DBPCFC both before the season and during the in-season challenges (P<0.05). Specific IgE against Golden Delicious increased during season (P<0.05), while neither SPT, HR, nor immunoblotting experiments could confirm an increase in reactivity. In conclusion, the results of the oral challenge tests indicated an increase in clinical reactivity to apples during the birch pollen season in birch pollen allergic individuals. 相似文献
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B. K. Pierson S. J. Giovannoni D. A. Stahl R. W. Castenholz 《Archives of microbiology》1985,142(2):164-167
An unusual filamentous, gliding bacterium was found in a few hot springs in Oregon where it formed a nearly unispecific top layer of microbial mats. It contained a bacteriochlorophyll a-like pigment and an abundance of carotenoids. There were no chlorosomes or additional chlorophylls. The organism was aerotolerant and appeared to be photoheterotrophic. It was successfully co-cultured with an aerobic chemoheterotroph in a medium containing glucose and casamino acids. Although it has many characteristics in common with the genus Chloroflexus, the lack of chlorosomes and bacteriochlorophyll c and the aerobic nature of this organism indicate that it should be placed in a new genus. This conclusion is supported by 5S rRNA nucleotide sequence data. 相似文献
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K Murray S Stahl P G Ashton-Rickardt 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》1989,324(1224):461-476
The simplest application of the modern genetic manipulation methods to vaccine development is the expression in microbial cells of genes from pathogens that encode surface antigens capable of inducing neutralizing antibodies in the host of the pathogen involved. This procedure has been exploited successfully for development of a vaccine against hepatitis B virus (HBV) that is now widely used. Similar approaches have been directed towards formulations for immunization against several other animal and human diseases and some of these preparations are now presently in trials. Of no less importance is the impact of biotechnology in providing reagents for fundamental studies of topics such as the determination of virulence, antigenic variation, virus receptors and the immunological response to viral antigens. The core antigen of HBV is a good example of a product of genetic engineering that is a valuable diagnostic reagent, and that is finding important use in immunological studies of particular pertinence to vaccine development. 相似文献
8.
U A Bommer G Lutsch J Behlke J Stahl N Nesytova A Henske H Bielka 《European journal of biochemistry》1988,172(3):653-662
The location of initiation factor eIF-2 and of its subunits in quaternary initiation complexes (40S-ribosomal-subunit.eIF-2. GuoPP[CH2]P.Met-tRNAf) was investigated by immunoelectron microscopy. Quaternary complexes were fixed with glutaraldehyde and reacted with affinity-purified polyclonal antibodies against eIF-2 alpha, eIF-2 beta or eIF-2 gamma. The dimeric immune complexes obtained by sucrose gradient centrifugation were investigated electron microscopically after negative staining. Antibody-binding sites were observed on the interface side of the 40S ribosomal subunit in the region between the 'head' and the 'body' (neck region) of the 40S ribosomal subunit. Within this region, eIF-2 alpha points to the rear side, whereas eIF-2 beta and eIF-2 gamma point to the frontal side of the 40S subunit indicating an elongated shape of eIF-2 about 15 nm long. By analytical ultracentrifugation of isolated eIF-2 the sedimentation and diffusion coefficients were determined to be 6.54 S and 4.74 x 10(-7) cm2/s respectively. From these data, a molar mass of 122.4 kg/mol and a dry volume of 147.4 nm3 were calculated. For the shape of eIF-2 a prolate ellipsoid of revolution is assumed with a maximal length of about 15 nm and with an axial ratio of about 1:3.5. This conclusion is further confirmed by a calculated frictional ratio of 1.37 and a Stokes radius of about 4.54 nm. 相似文献
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