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Intact stamens of Tradescantia were fixed, dehydrated, and infiltrated with an epoxy resin. Each stamen was then put into a drop of resin on a microscope slide, which was transferred to the stage of a dissecting microscope so that individual hairs could be detached from the filament with fine tungsten needles. The detached hairs were transferred to drops of resin ca. 2 mm in diameter (6 or 7 in each of two rows) lying on a slide heavily coated with evaporated carbon. Polymerization was carried out in an oven until the resin attained a degree of viscosity that permitted orientation of the isolated hairs (by using a compound microscope) without their subsequent dislocation. When the small drops of resin had hardened after further polymerization, the positions of the hairs were marked by circumscribing the cells with India ink. The block was pried from the slide after rapid cooling with solid CO2, and was then trimmed and sectioned. Cells suspended in culture medium were embedded in much the same way; they were centrifuged to obtain a pellet, which was fixed, dehydrated, and infiltrated. A small fragment of the pellet with a little resin was placed on a microscope slide, where the cells were dissociated under a dissecting microscope at ca. 100 × magnification. Individual cells were then picked up with tungsten needles and transferred to droplets of resin on a carbon-coated slide. The subsequent steps were similar to those described for the staminate hairs. Pieces of tissue in the 50-500 μ range were also handled by the foregoing technique. However, after infiltration they were put into large drops of resin on a slide coated with silicone mold-release rather than on a surface coated with carbon. 相似文献
65.
Clostridium putrefaciens: A Neglected Anaerobe 总被引:2,自引:1,他引:1
Helen E. Ross 《Journal of applied microbiology》1965,28(1):49-51
66.
Linkage analysis of seven kindreds with the X-linked lymphoproliferative syndrome (XLP) confirms that the XLP locus is near DXS42 and DXS37 总被引:5,自引:0,他引:5
James C. Skare Helen L. Grierson John L. Sullivan Robert L. Nussbaum David T. Purtilo Bakary S. Sylla Gilbert M. Lenon Dorothy S. Reilly Bradley N. White Aubrey Milunsky 《Human genetics》1989,82(4):354-358
Summary Analysis of seven kindreds indicates that the XLP locus exhibits 1% recombination with DXS42 (lod = 17.5) and no recombination with DXS37 (lod = 13.3). 相似文献
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Russell G. Snell Leslie M. Thompson Danilo A. Tagle Tracey L. Holloway Glenn Barnes Helen G. Harley Lodewijk A. Sandkuijl Marcy E. MacDonald Francis S. Collins James F. Gusella Peter S. Harper Duncan J. Shaw 《American journal of human genetics》1992,51(2):357-362
We report both a recombination event that places the Huntington disease gene proximal to the marker D4S98 and an extended linkage-disequilibrium study that uses this marker and confirms the existence of disequilibrium between it and the HD locus. We also report the cloning of other sequences in the region around D4S98, including a new polymorphic marker R10 and conserved sequences that identify a gene in the region of interest. 相似文献
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Abstract: K252a, an inhibitor of trk phosphorylation and nerve growth factor signal transduction in PC12 cells, blocked nerve growth factor-induced responses in cultured adult rat dorsal root ganglion sensory neurones. The nerve growth factor-dependent appearance of capsaicin sensitivity and accumulation of the neuropeptide substance P were inhibited when dorsal root ganglion neurones were grown in the presence of low concentrations (100 n M ) of K252a. At higher concentrations (3 µ M ), however, K252a stimulated the development of capsaicin sensitivity and the accumulation of substance P even in the absence of nerve growth factor. By using a wide dose range, therefore, we showed that K252a could either inhibit or mimic nerve growth factor's actions on sensory neurones. These results may explain the apparent paradox in the literature that some groups show a blocking effect of K252a on nerve growth factor-dependent survival of dorsal root ganglion sensory neurones, whereas others report that K252a can substitute for nerve growth factor or other trophic factors and promote neuronal survival. 相似文献
70.
Helen E. Chadd Ian R. Joint Nicholas H. Mann Noel G. Carr 《FEMS microbiology ecology》1996,21(2):69-76
Abstract: Laboratory cultures of marine Synechococcus sp. WH 7803 were grown under conditions of restricted iron availability. The culture medium was adjusted to restrict iron availability: (i) by adding the iron chelator EDDA; (ii) by omitting iron; and (iii) by omitting both iron and EDTA. An adaptive response was observed to these iron-restricted conditions, including a decrease in cellular phycoerythrin and synthesis of a 36 kDa polypeptide in [35 S]methionine radiolabelled whole cell lysates separated by SDS-PAGE. The polypeptide was synthesized within 48 h of transferring exponential phase cells to the iron-restricted medium. The protein was localized to the cell membranes and not the cytoplasmic fraction. 相似文献