摘要:

AbstractA variant subline of Chinese hamster cells (line CHO) was isolated that had increased resistance to detachment from the substratum. Comparisons between parental and variant cells of the complex carbohydrates liberated during trypsin detachment showed that the variant cells synthesized little or no hyaluronic acid. These cells also had reduced amounts of other complex carbohydrates in the cell periphery. However, parental and variant cells did not differ in morphology, growth control, or cyclic AMP concentration. Profound changes in the physical and chemical nature of the cell periphery, in themselves, evidently are insufficient to cause changes in many aspects of cell behavior.

ISSN:0021-9541    

DOI:10.1002/jcp.1040900302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractThe metabolic flow of trace amounts of D‐[14C]‐galactose was followed in cultures of transformed and untransformed hamster cells over a period ranging from five minutes to two hours. The results of chromatographic and enzymatic analyses of the soluble pools are described. Non‐glycolytic cells (previously deprived of sugar for periods of up to 24 hours) convert D‐galactose to galactose‐1‐phosphate and uridine diphosphoglucuronic acid in 10 to 20 minutes. In the same short assay time, glycolytic cells which have been maintained for 24 hours in media containing glucose or galactose convert D‐galactose to uridine diphosphogalactose and uridine diphosphoglucose (ratio 1.4:1). Longterm deprivation of sugar also results in 3‐ to 4‐fold increases in the uptake of galactose. In addition, the incorporation of galactose label into chloroform‐methanol soluble material appears to be influenced by the culture conditions of the untransformed cells while incorporation in the transformed cells appears unaffected. When cycloheximide is included in the maintenance medium for extended periods, the non‐glycolytic cells also show increases in galactose uptake rates but the glucose‐fed, glycolytic cells lose uptake ability. UDPhexose is the main galactose metabolic peak in the soluble pools of the cycloheximide‐treated, glycolytic and the cycloheximide‐treated, non‐glycolytic cells. The results of these experiments suggest that uptake of galactose and its subsequent metaboli

ISSN:0021-9541    

DOI:10.1002/jcp.1040900303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractThe adherence, phagocytic activity and buoyant density of mouse peritoneal exudate colony forming units (CFU‐PE) were investigated. There was a significant enrichment in the proportion of CFU‐PE in the adherent cells population, defined as cells adhering to a plastic surface within 30 minutes of incubation. The phagocytic activity of CFU‐PE was studied by incubating exudate cells with iron particles for 45 minutes. The cells were then separated into phagocytic and non‐phagocytic cell fractions by passing the incubation mixture through a magnetic field. A significant enrichment of CFU‐PE was seen in the phagocytic cell fraction. When exudate cells were fractionated in a Ficoll discontinuous density gradient, more than 88% of CFU‐PE were recovered at the 16/18% and 18/20% interfaces. It is concluded that CFU‐PE are adherent cells, have strong phagocytic activity and have a buoyant density between 1.0562 and 1.0703. When bone marrow cells were studied by these techniques, the committed stem cells for both granulocytes and macrophages (CFU‐C) were enriched in both non‐adherent cell and non‐phagocytic cells populations. In the Ficoll density gradient, CFU‐C banded at a heavier densi

ISSN:0021-9541    

DOI:10.1002/jcp.1040900304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractAge‐related changes in the cytokinetics of human diploid cellsin vitrohave been compared in normal cultures and in cultures in which lifespan has been prolonged by the addition of hydrocortisone to the medium. For both cultures, with advancing age the fraction of cells in the actively proliferating pool decreased and the intercellular variation in cell cycle times increased. The average cell cycle time was prolonged during aging due almost entirely to changes in the duration of G1. The duration of S remained constant, while a small delay in G2was observed in late passage cells near the end of their lifespan. Although the same pattern of change in proliferative parameters occurred in both control and hydrocortisone‐treated cultures, the changes were somewhat delayed in the presence of the steroid. The results are interpreted in terms of several cell cycle models and suggest that the events controlling cell proliferation are sensitive to hydrocortisone modulation during the G1and possibly the G2peri

ISSN:0021-9541    

DOI:10.1002/jcp.1040900305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractFriend erythroleukemic cells (FLC) can be induced to differentiate in vitro by addition of dimethylsulfoxide (DMSO). We have studied the kinetics of induction by measuring cell volume, volume coefficient of variation and cell doubling time. Two distinct volume changes (early and late) are observed after the addition of the inducing agent. The early change occurs after ten hours and consists of a 10–20% decrease in volume compared to an untreated control population. This shift persists for two days and its magnitude is proportional to both the concentration of DMSO and the number of differentiated cells seen on day 5. FLC lines which induce weakly or not at all with DMSO exhibit a reduced or absent early volume shift. Inclusion of a local anaesthetic in the culture prevents the appearance of differentiated cells and also counteracts the early volume shift. The exact time of the early volume change is a function of cell growth rate and appears to be cell cycle related. Synchronized cell populations exposed to DMSO during G2and S phase undergo one round of mitosis before expression of the volume change whereas cells in G2‐M express the change only after a second mitosis.A later, more gradual decrease in volume is observed in those cultures which begin to produce hemoglobin. It occurs after approximately five doubling times and coincides with the first appearance of hemoglobin‐containing cells. Volume distribution parameters indicate that only a proportion of the population becomes smaller in

ISSN:0021-9541    

DOI:10.1002/jcp.1040900306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractThe development of spike potential mechanisms during cell differentiation was studied in chick myotubes formed in vitro from trypsin‐dissociated myoblasts. The spike potential and its rate of rise were measured in myotubes from 4–14 day old cultures. A depolarizing current pulse was delivered to evoke the spike potential after the steady membrane potential had been adjusted to a standard level of −80 mV in all cases. This gives the greatest maximum rate of rise of the spike potential and eliminates variation due to differences in the resting membrane potential of the myotubes. The size and maximum rate of rise of the spike potential increased significantly during the period examined. The spike potential was blocked by tetrodotoxin in almost all myotubes. These results suggest that during differentiation myotubes develop the ability to generate a spike potential due to an inward current carried by sodium

ISSN:0021-9541    

DOI:10.1002/jcp.1040900307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractBromodeoxyuridine (BrdU) incorporation into cellular DNA has a differential effect on the cell‐associated fluorescence of several DNA‐specific dyes. After cells were treated with BrdU, flow microfluorometry was used to study the relative increase or decrease in fluorescence of stained cells. Bromodeoxyuridine incorporation into CHO cells increased the fluorescence of mithramycin‐, olivomycin‐, or chromomycin‐stained cells, decreased that of propidium iodide‐stained cells, and had little, if any, effect on the fluorescence of acriflavine Feulgen‐stained cells. Changes in relative fluorescence of cell‐associated dyes are due to changes in the amounts of dye bound to cells with BrdU‐substituted DNA. Colorimetric and absorbance measurement of DNA content showed that BrdU does not alter the diploid DNA content of CHO cells; however, BrdU induces perturbations in the distribution of cells about the cell cycle which cause an increase ina

ISSN:0021-9541    

DOI:10.1002/jcp.1040900308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractBone marrow cells from normal rats were separated by velocity sedimentation into three distinct populations corresponding to granulocytes, lymphocytes and reticulocytes. Cells from each population were surface labelled via the lactoperoxidase radioiodination or the tritiated borohydride reduction. Distinct labeling patterns were observed on SDS‐PAGE for each cell population. Separation of bone marrow cells from anemic rats injected with TAB vaccine led to four populations corresponding to successive stages of erythroid cell maturation. Labelled protein patterns were not in this case as different from one population to the other, except for one species which increased in intensity with the degree of maturation. The tritiated glycoprotein profiles show a shift from high to low molecular weight species during the process of maturatio

ISSN:0021-9541    

DOI:10.1002/jcp.1040900309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractWe have examined the relative quantities of 18S and 28S rRNA, 4S RNA and poly (A) + mRNA in the following cultured cells: the mouse fibroblast lines 3T3 and 3T6 in the resting (contact inhibited) and growing (sparse) states, 3T3 clones transformed with SV40 (SV3T3) and with both SV40 and polyoma (SV‐Py 3T3), hamster lung fibroblasts (V79), human cervical carcinoma cells (HeLa), and human diploid fibroblasts at early and late passage. The relative quantities of the RNA species were determined by labeling the cells to equilibrium with32PO4and measuring the amount of label in each RNA species.The ratio of mRNA to rRNA varied from 1.1% to 2.7% in the different cell lines, the more rapidly growing cell lines usually giving a higher ratio. In cells experiencing growth limitation either by contact inhibition or due to senescence, the ratio of mRNA to rRNA was about 30% lower than in the corresponding cells in the growing state. In most cell lines the ratio of 4S RNA to 18S rRNA was between 0.8 and 1.2, but in senescent fibroblasts, this ratio increased to greater than 1.7. Senescent fibroblasts also contained much more total RNA per unit of DNA than the same cells at early passage or than 3T6 or 3T3 cell

ISSN:0021-9541    

DOI:10.1002/jcp.1040900310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractThe effect of granulocyte‐macrophage colony stimulating factor (GM‐CSF) on the synthesis of RNA in liquid cultures of mouse bone marrow, spleen, thymus, peritoneal, peripheral blood leukocytes and lymph node cells was investigated. GM‐CSF appeared to stimulate RNA‐synthesis in syngeneic bone marrow cells within ten minutes of adding it to the culture. In the presence of GM‐CSF bone marrow cultures maintained their initial rate of RNA synthesis for approximately ten hours. GM‐CSF had no apparent effect on the uptake of3H‐uridine into bone marrow cells. This stimulation was still observed in the presence of puromycin and cycloheximide, but was abrogated by actinomycin D. The magnitude of the stimulation was not affected by the density of cells between 1 and 20 × 106cells/ml but was slightly smaller at 0.1 and 40 × 106cells/ml. Increasing concentration of GM‐CSF (up to 2 × 105units per ml) led to increased stimulation of RNA synthesis in bone marrow cells, but a significant stimulation could be detected at concentrations as low as 800 units/ml.GM‐CSF did not significantly stimulate RNA synthesis in spleen, thymus, mesenteric or subcutaneous lymph node cells. However a small stimulation was observed in peripheral blood leukocytes and peritoneal cells.Autoradiographic studies showed that GM‐CSF stimulated RNA synthesis in blast cells, myelocytes, metamyelocytes and polymorphs. Nucleated erythroid cells showed no increased labeling with GM‐CSF. Labeling in lymphoid‐like cells was highly variable but the level of labeling did not appear

ISSN:0021-9541    

DOI:10.1002/jcp.1040900311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY