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991.
Two taxa of Carthamus, each with 32 pairs of chromosomes, merit specific status. C. baeticus (Boiss. & Reut.) Nym. is found on islands of and in countries surrounding the Mediterranean Sea, whereas C. turkestanicus Popov extends from western Turkey to Kashmir. Compared to C. baeticus, C. turkestanicus has wider leaves, wider and less divaricate bracts, larger heads with more florets and achenes, and florets with longer lobes. Their chromosomes differ to the extent that microsporocytes of their F1 hybrids had a reciprocal translocation in pachytene and a mean of over six, and up to 22, univalents at metaphase I. Pollen stainability and seed fertility were reduced in F1 hybrids. 相似文献
992.
Summary Small samples of soil amended with 2% (w/w) of glucose were preincubated either aerobically or anaerobically and then assayed
(N2
15 and C2H2-C2H4) either aerobically or anaerobically for different time periods. One-hour C2H2-C2H4 assays showed greatest activity when anaerobic assay followed anaerobic preincubation. During the anaerobic preincubation
a lag of 12–24 h occurred before rapid increase in one-hour assay activity was observed. When aerobic assay followed aerobic
preincubation a longer lag was observed and lower activities were obtained. When anaerobic assay followed aerobic preincubation
(orvice versa) negligible activities were observed in short assays, and longer assays showed increasing activity related to changes in
atmosphere and/or microbial population in the closed system.
Preincubation of soil on a diffusion gradient at a series of different partial pressures of oxygen confirmed the above pattern
and showed that as preincubation pO2 increased, the anaerobic assay activity rapidly decreased. As preincubation pO2 decreased from 0.2 atm the aerobic assay activity decreased but less rapidly.
The activities observed were related to the sizes of the Azotobacter and Clostridium populations. There was no evidence of
aerobic or anaerobic C2H2 reduction in any cultures of ‘oligonitrophiles’ isolated.
Incorporation of N2
15 was related to C2H2 reduction activity in the soil system studied. However, observed C2H4/N2 molar ratios ranged from 10 to 22 and appeared to be highest in samples which were preincubated anaerobically.
Issued as Macdonald College Journal Series No.618 and as Canadian IBP contribution No.84. 相似文献
993.
Monoclonal antibody to murine embryos defines a stage-specific embryonic antigen expressed on mouse embryos and human teratocarcinoma cells 总被引:16,自引:0,他引:16
A murine stage-specific embryonic antigen (SSEA3) is defined by reactivity with a monoclonal antibody prepared by immunization of a rat with 4- to 8-cell-stage mouse embryos. This antigenic determinant, present on oocytes, becomes restricted first to the inner cell mass at the blastocyst stage, and later to the primitive endoderm. Murine teratocarcinoma stem cells do not react with this antibody, whereas human teratocarcinoma stem cells are SSEA3-positive. This antigenic determinant is not expressed on a variety of other human and murine cell lines, but is found on the surface of human erythrocytes. It is a carbohydrate and is present on both cell-surface glycolipids and glycopeptides. These results demonstrate the feasibility of identifying stage-specific antigenic determinants with monoclonal antibody prepared against embryos. The need for thorough screening on a variety of cell types to establish developmentally important cross-reactivities is also emphasized. 相似文献
994.
The hapten structure of a developmentally regulated glycolipid antigen (SSEA-1) isolated from human erythrocytes and adenocarcinoma: a preliminary note 总被引:10,自引:0,他引:10
S Hakomori E Nudelman S Levery D Solter B B Knowles 《Biochemical and biophysical research communications》1981,100(4):1578-1586
Glycolipid antigen reacting to the monoclonal antibody directed to the developmentally regulated antigen SSEA-1 was isolated from human erythrocytes and colonic adenocarcinoma. The antigens have the Lex (Galβl→4[Fucα]→3]GlcNAcβl→R) or Ley (Fucαl→2Galβl→4[Fucαl→3]GlcNAcβl→R) structure at the termini of the branched polylactosaminolipid. In addition, a novel polyfucosyl structure locating exclusively at the internal GlcNAc was detected in the tumor antigen. The antibody reacts with a simple monovalent Lex glycolipid (Galβl→4[Fucαl→3]GlcNAcβl→3Galβl→4Glcβl→Cer) previously isolated from colonic carcinoma when presented at a high density on liposomes. The antibody therefore may react to the bivalent or multivalent Lex or Ley structure. 相似文献
995.
The use of flow microfluorimetry in the analysis of the phenotype expression of mouse histocompatibility antigens 总被引:1,自引:0,他引:1
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Quantitation of the expression of cell surface antigens has hitherto been limited to analysis by either cytotoxicity tests or radioimmune assays (5, 15). We report here the use of a new methodology to analyze and quantitate the expression of mouse histocompabililty antigens (H-2 locus) in hybrid clones and parental cell types. The binding of fluorescein-tagged antibody is measured on a cell-to-cell basis in large viable cell populations using flow microfluorimetric techniques. These techniques have been used to measure hapten and immunoglobulin binding to lymphocyte populations (8, 9, 14). However, this is the first report in which these techniques have been used to examine the expression of the H-2 locus. The advantage of this approach is twofold: first, a large and statistically significant sample population may be analyzed one cell at a time, thus revealing the fine detail of heterogeneity in the expression of the cell surface markers within a population. Second, as has been demonstrated for analysis of specific components of the immune system, this method does permit fluorescence-activated sorting of cell types according to their different surface populations (8, 9, 14). 相似文献
996.
G Knowles 《The Journal of experimental biology》1976,64(1):131-140
Recent evidence suggests that the isolated Malpighian tubules of Calliphora possess mechanisms which restrict the loss of glucose and trehalose from the insect. This report establishes that the intact, diuresing fly does not excrete glucose or trehalose when solutions of these sugars are injected. When solutions of non-metabolized sugars such as sorbose and xylose are injected into the fly, these sugars are rapidly excreted. High concentrations of sorbose and xylose are found in the urine, suggesting that rapid reabsorption of fluid occurs in the excretory apparatus even during the diuresis which the injections provoke. However, injected sucrose is apparently not excreted in large amounts and it is possible that the Malpighian tubules when functioning in vivo are impermeable to disaccharides. 相似文献
997.
Effects of 2-deoxyglucose, glucosamine, and mannose on cell fusion and the glycoproteins of herpes simplex virus. 总被引:9,自引:9,他引:0
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2-Deoxyglucose and glucosamine were found to inhibit cell fusion caused by a syncytial mutant of herpes simplex virus and to inhibit the glycosylation of viral glycoproteins in the infected cells. The inhibition of fusion and the inhibition of glycosylation caused by 2-deoxyglucose were substantially prevented when mannose was also present during infection. When glycosylation was inhibited, three new bands were found in major glycoprotein region on sodium dodecyl sulfate-polyacrylamide gels. These bands may be precursors to the normal glycoproteins. The correlation between fusion and glycosylation in the presence of 2-deoxyglucose, glucosamine, and mannose suggests that the cells cannot fuse if their glycoproteins have a considerably reduced carbohydrate content. 相似文献
998.
Kinetics of Cell Fusion Induced by a Syncytia-Producing Mutant of Herpes Simplex Virus Type I
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Stanley Person Robert W. Knowles G. Sullivan Read Susan C. Warner Vincent C. Bond 《Journal of virology》1976,17(1):183-190
We have isolated a number of plaque-morphology mutants from a strain of herpes simplex virus type I which, unlike the wild type, cause extensive cell fusion during a productive viral infection. After the onset of fusion, there is an exponential decrease in the number of single cells as a function of time after infection. At a multiplicity of infection (MOI) of 3.8 plaque-forming units per cell, fusion begins 5.3 h after infection with the number of single cells decreasing to 10% of the original number 10.2 h after infection. As the MOI is gradually increased from 0.4 to 8, the onset of fusion occurs earlier during infection. However, when the MOI is increased from 8 to 86, the onset of fusion does not occur any earlier. The rate of fusion is independent of the MOI for an MOI greater than 1. The rate of fusion varies linearly with initial cell density up to 3.5 × 104 cells/cm2 and is independent of initial cell density at higher cell concentrations. To assay cell fusion we have developed a simple quantitative assay using a Coulter counter to measure the number of single cells as a function of time after infection. Data obtained using a Coulter counter are similar to those obtained with a microscope assay. 相似文献
999.
Summary Erythromycin-resistant mitochondria from species 1, 5 and 7 of P. aurelia were injected into erythromycin-sensitive paramecia of each of the same three species. Mitochondria from species 1 and 5 were successfully transferred to all three species, but species 7 mitochondria failed to develop in species 1 and 5. Minor differences were indicated in the frequency of successful transfers of species 1 mitochondria into species 1 and 5 cells. From studies on the transferability of mitochondria from hybrid cells, containing mitochondria from one species and nuclei from another, it was concluded that mitochondrial compatibility was mainly under control of the nuclear genome, with a possible minor control also by the mitochondrial genome.Dedicated to T.M. Sonneborn on the occasion of his seventieth birthday. This paper is part of a Sonneborn Festchrift most of which will appear in Genetical Research in 1976. 相似文献
1000.