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161.
Suzanne M. Watt David J. Gilmore Donald Metcalf Stephen P. Cobbold Trang K. Hoang Herman Waldmann 《Journal of cellular physiology》1983,115(1):37-45
A rat monoclonal antibody, YBM/42, directed against mouse leukocyte common antigen, was used for the analysis and separation of hemopoietic progenitor cells from mouse bone marrow and fetal liver. Cells were fractionated on a FACS-II cell sorter and the resulting subpopulations examined for their morphology and ability to form colonies in agar (for day 7 colonies) and methylcellulose (for day 2 erythroid clones). The antibody bound to all leukocytes, including blast cells and day 7 hemopoietic progenitor cells (day 7 colony forming cells, CFC), but not to erythrocytes or nucleated erythroid cells. This antibody can be used to advantage to enrich for early progenitor cells from mouse fetal liver, in which the majority of cells (70%) are nucleated erythroid cells. In day 12 fetal liver, approximately 10% of all cells bind this antibody strongly and, of these approximately 70% are blast cells. Contained within this positive population are 95% of all day 7 CFC. In the most enriched fraction about 20% of the cells formed day 7 colonies. This represents a 25-fold enrichment over unsorted fetal liver. The negative fractions contain 94% of all cells forming erythroid clones (≥8 cells) on day 2 of culture (day 2 CFU-E). In the most enriched fraction, 20% of the cells are day 2 CFU-E. Day 7 CFC can therefore be well separated from day 2 CFU-E, with good recovery of both cell types, by use of a single label. Day 7 colony forming cells were classified as granulocyte (G-CFC), macrophage (M-CFC), mixed granulocyte/macrophage (GM-CFC), pure erythroid (E), or mixed erythroid (Emix). A high enrichment for multipotential cells is achieved and constitues 3–5% of cells in the most enriched fraction. Most types of day 7 CFC could not be separated with YMB/42, but GM-CFC and M-CFC exhibit a broader distribution than the other CFC with regard to fluorescence intensity. This implicit heterogeneity in GM-CFC and M-CFC is further substantiated by the finding that myeloid progenitors in the different FACS fractions also share a differential reactivity to different sources of growth factors. 相似文献
162.
Donald Spencer Peter M. Chandler Thomas J. V. Higgins Adam S. Inglis Michael Rubira 《Plant molecular biology》1983,2(5):259-267
Serological studies and comparison of N-terminal amino acid sequences with the amino acid sequence deduced from a cDNA clone have been used to establish the sequence relationships between the subunits of the pea seed storage protein, vicilin. Subunits smaller than Mr~50 000 (i.e., Mr 34 000, 30 000, 25 000, 18 000, 14 000, 13 000 and 12 000) show extensive homology with molecules within Mr~50 000 group. Both the sequencing and serological data confirm earlier evidence from studies on vicilin synthesisin vivo andin vitro which indicated that the vicilin subunits smaller than Mr~50 000 arose by endoproteolytic cleavage of parent molecules within the Mr~50 000 group. Cleavage in different Mr 50 000 parent molecules containing either one or both of two susceptible processing sites accounts for the formation of all the vicilin subunits smaller than Mr~50 000, with the possible exception of the Mr34 000 polypeptide. The position of these sites in the putative parents were defined by reference to a complete amino acid sequence deduced from the sequence of DNA complementary to mRNA for one member of the Mr~50 000 group. 相似文献
163.
Donald C. Morizot Jeffrey A. Greenspan Michael J. Siciliano 《Biochemical genetics》1983,21(9-10):1041-1049
Electrophoretic variation ascribable to three protein-coding loci, coding for glutamine synthetase (GS), uridine monophosphate kinase (UMPK), and transferrin (Tf), was observed in three species of fish of the genus Xiphophorus. Electrophoretic patterns in interspecific F1 hybrid heterozygotes suggested monomeric subunit structures of UMPK and Tf and a multimeric structure of undetermined subunit number of GS. Linkage analyses in backcross hybrids indicated a recombination map of GS-0%-Tf-10.8%-UMPK. This group (designated Xiphophorus linkage group VI) was shown to assort independently from the 14 enzyme loci assigned to linkage groups I-V and from 19 other informative markers within the limits of the data. 相似文献
164.
165.
Studies of the limited degradation of mucus glycoproteins. The effect of dilute hydrogen peroxide. 总被引:5,自引:3,他引:2
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1. The action of dilute H2O2 on a series of ovarian-cyst glycoproteins and glycopolypeptides was investigated. 2. Both native glycoproteins and the glycopolypeptides were carbohydrate-rich, of relatively low molecular weight and of simple structure. 3. At pH 5.6 and 37 degrees C, exposure to H2O2 for a limited time brought about a partial degradation, the molecular weight being decreased by 2-4-fold. 4. Carbohydrate analysis showed very little change in the oligosaccharide moiety, apart from a small decrease in sialic acid in some samples. 5. Amino acid analysis showed minor changes in serine, threonine and proline contents, but almost total loss of histidine. Concomitantly, there was a small gain in aspartic acid. 6. Myosin, examined at both pH 5.7 and 6.7, exhibited generally similar behaviour, there being losses of other amino acid residues as well as histidine: the viscosity was decreased to a low value, and a range of peptides of widely varying size was produced. 7. It is suggested that attack on the histidine residue, with partial conversion into aspartic acid, is accompanied by scission of the histidyl peptide bond. 相似文献
166.
Francis C. Monette Bernard S. Morse Donald Howard Eero Niskanen Frederick Stohlman Jr 《Cell proliferation》1972,5(2):121-129
The ability of a single injection of killed, intact bacteria to effect an increase in the proliferative rate of hemopoietic stem cells was studied. The total numbers of colony forming units in bone marrow, spleen and peripheral blood as well as the proportion of CFU in cycle was assessed. Splenic CFU were observed to rise exponentially due initially to in situ proliferation and later to proliferation in bone marrow with migration via the blood to the spleen. The results are discussed in the light of current concepts of stem cell regulation. 相似文献
167.
The effect of a number of inorganic anions on the quaternary structure of C-phycocyanin has been investigated by fluorescence polarization. Dissociation to monomer occurred in the order: SCN− > ClO4− > NO3− > Br− > Cl−. These results suggest that hydrophobic interactions are important in the hexamer-monomer equilibrium of C-phycocyanin. 相似文献
168.
Effects of Optically Active 1-(α-Methylbenzyl)-3-(3,4-dichlorophenyl)urea on Reactions of Mitochondria and Chloroplasts
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Effects of the R- and S-isomers and racemate of 1-(alpha-methylbenzyl)-3-(3,4-dichlorophenyl)urea (MBPU) were measured on phosphorylation and electron transport in mung bean (Phaseolus aureus L.) mitochondria and spinach (Spinacia oleracea L.) chloroplasts.In chloroplasts, S-MBPU inhibited basal and methylamine-uncoupled electron transport with ferricyanide as the oxidant, both photoreduction and coupled photophosphorylation with water as the electron donor and with ferricyanide and nicotinamide adenine dinucleotide phosphate (NADP) as oxidants, and cyclic photophosphorylation with phenazine methosulfate as the electron mediator under an argon gas phase. With ascorbate 2,6-dichloro-phenolindophenol as the electron donor, phosphorylation coupled to NADP reduction was inhibited, but the reduction of NADP was not inhibited. The R-isomer of MBPU, like the S-isomer, inhibited all of the photophosphorylation reactions studied. However, unlike the S-isomer, the R-isomer either did not inhibit or was a very weak inhibitor of all photoreduction reactions. The effects of the MBPUs on the chloroplast reactions can be explained by action at two different sites: an optically specific site near photosystem II and the oxygen evolution pathway, and a second optically nonspecific site associated with the generation of ATP.In mitochondria, both the R- and S-isomers stimulated state 4 respiration, inhibited state 3 respiration, and released oligomycin-inhibited respiration with malate, succinate, and NADH as substrates. Both enantiomers were equally active in all studies with malate and succinate as substrates. However, with NADH as substrate, R-MBPU was a stronger inhibitor of state 3 respiration and a weaker stimulator of state 4 respiration than S-MBPU. 相似文献
169.
This study was designed to test the hypothesis that in some species of primates individual differences in responsiveness to certain situations is related to dominance status. During the first phase of the study, the existence of a linear dominance hierarchy was confirmed by ratings of agonistic interactions. In the second phase, bar-pressing behavior was recorded on a cumulative recorder while the experimenter simultaneously rated, at 30-second intervals, all animals present in the research setting. Results indicated that dominance status was systematically related both to rate of bar-pressing and to duration of response blocks, with the more dominant animals bar-pressing at slower rates for longer blocks of time. The finding that individual differences in rate did not vary with social context suggests that dominance-related differences in responsiveness may be quite stable. Certain dominancerelated trends in the variation of social context in the research setting were also noted. 相似文献
170.
Summary The role of microtubules in tracheary element formation in cultured stem segments ofColeus has been investigated through the use of the antimicrotubule drug, colchicine. Colchicine treatment of the cultured stem segments produced a dual effect on xylem differentiation. If applied at the time of stem segment isolation or shortly thereafter, wound vessel member formation is almost completely blocked. However, if colchicine is applied after the third day of culture, it does not inhibit differentiation, but instead large numbers of xylem elements are formed which have highly deformed secondary walls. Both effects are related to colchicine's specific affinity for microtubules. In the first case it is shown that colchicine blocks mitosis, presumably by destroying the spindle apparatus, and thus inhibits divisions which are prerequisite for the initiation of xylem differentiation. While, if colchicine is applied after the necessary preparative divisions have taken place, it destroys specifically the cortical microtubules associated with the developing bands of secondary wall, thus causing aberrant wall deposition.Light and electron microscopic analysis of drug-treated cells reveals that the secondary wall becomes smeared over the surface of the primary wall and does not retain the discrete banded pattern characteristic of secondary thickenings in untreated cells. Examination of colchicine-treated secondary walls in KMnO4 fixed material shows that in the absence of microtubules the cellulose microfibrils lose their normal parallel orientation and are deposited in swirls and curved configurations, and often lie at sharp angles to the axis of the secondary wall band. Microtubules, thus, appear to play a major role in defining the pattern of secondary wall deposition and in directing the orientation of the cellulose microfibrils of the wall. Factors in addition to microtubules also act in controlling the secondary wall pattern, since we observe that even in the absence of microtubules secondary thickenings of two adjacent xylem elements are deposited directly opposite one another across the common primary wall. 相似文献