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  • Cell & Developmental Biology  (2,435)
  • 1975-1979  (1,486)
  • 1965-1969  (919)
  • 1905-1909  (30)
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  • 201
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 98 (1979), S. 125-136 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Stable variants of the macrophage-like cell line J774.2, defective in adenylate cyclase and protein kinase activities, were selected by cloning cells resistant to the growth-inhibitory effect of cholera toxin and 8-bromoadenosine 3′:5′ cyclic monophosphoric acid (8 Br-cAMP), respectively. These variants were analyzed for their ability to respond to cyclic AMP-mediated enhancement of phagocytosis and cyclic AMP-mediated inhibition of plasminogen activator secretion and growth. The adenylate cyclase variants were unaffected by cholera toxin but were sensitive to 8 Br-cAMP-mediated inhibition of plasminogen activator secretion and growth. One of these variants exhibited a defect in phagocytosis that could be corrected by 8 Br-cAMP. The protein kinase variants exhibited normal basal phagocytosis that could not be stimulated by either 8 Br-cAMP or cholera toxin; they were also insensitive to cyclic AMP-mediated inhibition of plasminogen activator secretion and growth. The studies demonstrate that the three effects of cyclic AMP in J774.2-inhibition of growth and plasminogen activator secretion, and enhancement of basal Fc-mediated phagocytosis-are mediated by a cyclic AMP-dependent protein kinase. The results support the usefulness of variants in cyclic nucleotide metabolism in understanding the regulation of differentiated cell function by cyclic AMP.
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  • 202
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 98 (1979), S. 137-144 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effect of phytohemagglutinin (PHA) on lymphocytes was examined with respect to free intracellular water volume and intracellular [K+]. At a cell concentration of 30 × 106 lymphocytes/ml in modified Hank's Buffered Salt Solution (HBSS) in the presence of 10% human AB serum, addition of PHA at 3 mg/ml resulted in a 24-27% decrease in free intracellular water space within 30 to 60 minutes and a return to control level after three hours. A larger change in intracellular water (44%) was observed under similar conditions in the absence of serum. The absolute intracellular K+ content did not change after PHA addition, but the cell water volume decrease arising from PHA addition resulted in a 29% increase in intracellular [K+] at 60 minutes. The decrease in lymphocyte water volume induced by PHA was also observed for concanavalin A which stimulates lymphocyte proliferation, but not for wheat germ lectin, an agglutinating agent which is not mitogenic. Thus, volume regulation may be closely associated with the mitogenicity of these compounds.
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  • 203
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 98 (1979), S. 161-166 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Adhesion between cells of different tissues from chick embryos was studied by the modified collecting particle (Pessac et al., 1977a) and stationary monolayer assays. These assays measure the number of 3H labeled cells that adhere to the surface of cell aggregates and tissue fragments or on top of cell monolayers. The numbers of cells from a given suspension that adhere to identical or different cells can be compared. Intercellular adhesion may be considered as tissue specific if, in identical conditions, more cells adhere to identical cells than to cells from different tissues. Neural retina, cerebrum, optic tectum, liver and kidney cells from 9-day-old chick embryos showed no tissue specificity of adhesion, while heart cells adhered preferentially to collecting heart fragments.
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  • 204
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 100 (1979), S. 519-529 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The interaction of mitogenic factors on a single cell type and the comparative activity of a given factor in diverse cell types have been studied byapplying the principles of Michaelis-Menten kinetics to clonal growth data. Such comparisons are facilitated by derivation of two parameters; Kmmitogen, the mitogen concentration that gives half-maximal clonal growth and a theoretical maximal growth rate, RMAXT. Both parameters are analogous to the Km and VMAX as applied to enzymatic reactions. Use of these parameters permits meaningful comparisons between cells with different growth rates.Using kinetic analysis of dose-response data, we found that normal human epithelial cells require 200 times more fetal bovine serum protein (FBSP) than a malignant line to multiply at their respective half-maximal rates. Further, the KmFBSP of normal cells was reduced to that of the malignant line by the inclusion of growth factors (EGF or FGF, and hydrocortisone) in the medium. On the other hand, even though greater levels of serum were required when growth factors and hydrocortisone were not present, their inclusion did not alter RMAXT. Interactions between mitogenic factors were shown to be unidirectional. Although EGF reduced the KmFBSP, FBSP did not change the KmEGF. The same type of analysis revealed that hydrocortisone, which potentiated the mitogenic activity of EGF did not change the KmEGF. Kinetic analysis of cell growth should prove useful in studies on the relation between growth and tumor promotion as well as in the evaluation of growth-inhibiting chemotherapeutic agents.
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  • 205
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 100 (1979), S. 539-550 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Binding of Concanavalin A to mouse L cells which were grown in serum free, chemically defined medium and depleted of their membrane sterol by blocking their de novo sterol synthesis was investigated. Kinetic analysis of binding data implied positive cooperativity, with two different affinities for Con A, in both experimental and control cultures. The amount of Con A bound to the cell surface at saturation was approximately 0.5 picomoles per mg cellular protein in controls and approximately 1.0 picomoles per mg cellular protein in 25-hydroxycholesterol treated cultures (which had a reduced sterol concentration of up to 50% in their plasma membranes). This phenomenon was reversed when cholesterol or mevalonate was added to the inhibited cultures to compensate for their inability to synthesize sterol. Our findings indicate that lectin binding to specific glycoprotein receptors is influenced by membrane lipid composition.
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  • 206
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 100 (1979), S. 579-588 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A novel variant of S49 mouse lymphoma cells is described which is resistant to growth arrest and cytolysis by dibutyryl cyclic AMP but, in contrast to previously described variants, has normal cyclic AMP-dependent protein kinase. The variant is also resistant to N6-monobutyryl cAMP but is sensitive to killing by 8-bromo cAMP and cholera toxin. Extracts of the variant appear to contain wild type levels of both O2′-butyrylesterase and cyclic AMP phosphodiesterase activities. Accumulation of exogenous [3H]dibutyryl cyclic AMP is reduced in the variant suggesting a defect in either uptake or secretion of the analog or its metabolic products. Accumulation of cyclic AMP in variant cells after stimulation of adenylate cyclase with either isoproterenol or cholera toxin is also reduced compared with wild type cells, although cyclase activity of membranes prepared from the variant cells is normal. Extracellular accumulation of cyclic AMP after stimulation of variant cells with isoproterenol is greater than that found with wild type cells. It is concluded that the variant has an alteration in its cyclic AMP secretion mechanism resulting in more efficient extrusion of cyclic AMP than in wild type cells.
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  • 207
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 101 (1979) 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 208
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    Journal of Cellular Physiology 101 (1979), S. 1-8 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have produced somatic cell hybrids between totipotent mouse teratocarcinoma cells and rat hepatoma cells. These hybrids were tested for the expression of liver specific functions expressed in the hepatoma cell parent and for their ability to differentiate when injected into nude mice. The results of this study indicate that hybrid cell clones do not resemble either of the parental cells, since they do not produce albumin and tyrosine aminotransferase that are expressed in the rat hepatoma parent, and are incapable of forming either teratocarcinoma or hepatomas when injected in experimental animals.
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  • 209
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 101 (1979), S. 9-16 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: When serum is made rate-limiting for clonal multiplication of human diploid fibroblasts, the presence of a 2-oxocarboxylic acid in the medium becomes essential. The requirement is independent of the 20 amino acids and glucose. Glyoxylic, pyruvic, 2-oxoglutaric, and oxalacetic acids are most effective. The types of 2-oxocarboxylic acids that support multiplication are oxidized substrates for several, pyridine nucleotide-linked intracellular oxidoreductases. The requirement is not satisfied by carboxylic acids, oxidized substrates for oxidoreductases that are not linked to pyridine nucleotides, or by nonspecific electron acceptors. The quantitative requirement for 2-oxocarboxylic acids in cell multiplication is markedly affected by the concentration of serum proteins in the medium. Therefore, 2-oxocarboxylic acid metabolism may be related to the mechanism by which serum growth factors regulate cell multiplication.
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  • 210
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 101 (1979), S. 129-138 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effect of insulin on glucose entry has been studied in monolayer cultures of human diploid fibroblastic cells. Influence of insulin on total cell glucose incorporation was evaluated using [14C] glucose. Glucose incorporation was increased up to two-fold in the presence of insulin. Insulin action occurred within 30 minutes and could be observed with insulin concentrations as low as 10-10 M (10 μU/ml). The action of insulin was enhanced by preincubation in glucose-free medium. After glucose starvation the cells converted glucose primarily to glycogen and nucleotides, and the stimulation by insulin was observed equally in both fractions.Influence of insulin on the kinetics of hexose transport was studied using 2-deoxyglucose and 3-0-methyl glucose. A large diffusion component was corrected using ρ-chloromercuribenzoic acid or phloridzin. Km for facilitated diffusion averaged 1.9 mM for 2-deoxyglucose and 5.3 mM for 3-0-methyl glucose, and Vmax ranged from 10-24 nmoles/min/mg cell protein. Insulin resulted in a 150% increase in Vmax with no significant change in Km. The data suggest that human diploid fibroblasts can be a useful system for the study of insulin's glucoregulatory action.
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  • 211
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 99 (1979), S. 369-381 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Friend erythroleukemic cells can be induced by a variety of agents to synthesize hemoglobin and to exhibit other characteristics suggesting erythroid maturation. Upon induction of hemoglobin synthesis with dimethyl-sulfoxide (DMSO), the chloride flux in Friend cells gradually increases, until after five days of exposure to DMSO (when the hemoglobin content of the cells approaches that of the mature erythrocyte) the flux is three times the value in non-induced cells. A similar flux increase is observed in the presence of a different type of inducer, hypoxanthine, but no increase in flux is seen in the mutant cell line, TG-13, which does not synthesize hemoglobin after DMSO treatment. Thus, the flux increase seems to be associated with the induction process, rather than being a direct effect of the inducing agent. After DMSO treatment, the sulphate flux decreases and the chloride/sulphate selectivity increases, as would be expected if the cells were becoming more like red cells. On the other hand, the sensitivity of the chloride flux to the inhibitor, furosemide, and to temperature is the same in the induced as in the non-induced Friend cells, and different from that of the mature red cell. Thus, the anion transport properties of the induced Friend cell are different from those of both the non-induced Friend cell and the mature erythrocyte. Either the system in the induced cell represents an intermediate stage in the development of the mature red cell characteristics, or else the maturation of transport function in the Friend cell differs from that in normal erythrocyte precursors.
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  • 212
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 101 (1979), S. 173-200 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The intracellular accumulation of free [3H] adenosine was measured by rapid kinetic techniques in P388 murine leukemia cells in which adenosine metabolism (phosphorylation and deamination) was completely prevented by depletion of cellular ATP and by treatment with deoxycoformycin. Nonlinear regression of integrated rate equations on the data demonstrate that the time courses of labeled adenosine accumulation at various extracellular adenosine concentrations in zero-trans and equilibrium exchange protocols are well described by a simple, completely symmetrical, transport model with a carrier:substrate affinity constant of about 150 μM. Adenosine transport was not affected by 1 mM deoxycoformycin indicating that this analog has a low affinity for the nucleoside transport system. The transport capacity of dog thymocytes and peripheral leukocytes was similar to that of P388 cells. Transport was not inhibited by deoxycoformycin and remained constant during the first two hours after mitogenic stimulation with concanavalin A.In untreated, metabolizing P388 cells transport was found to be the major determinant of the rate of intracellular metabolism, regardless of the extracellular adenosine concentration (up to at least 160 μM), but the long-term accumulation (longer than 30-60 seconds) of radioactivity from extracellular adenosine strictly reflected the rate of formation of nucleotides (mainly ATP). The metabolism of adenosine by whole cells was entirely consistent with the kinetic properties of the transport system and those of the metabolic enzymes. At low exogenous adenosine concentrations (1 μM and below) transport was slow enough to allow direct phosphorylation of most of the entering adenosine. The remainder was deaminated and rapidly converted to nucleotides via inosine, hypoxanthine, and IMP. At concentrations of 100 μM or higher, on the other hand, influx exceeded the maximum velocity of adenosine kinase about 100 times so that most of the entering adenosine was deaminated. But since the maximum velocity of adenosine deaminase exceeded those of nucleoside phosphorylase and hypoxanthine/guanine phosphoribosyltransferase about 5 and 100 times, respectively, hypoxanthine and inosine rapidly exited from the cells and accumulated in the medium. A 98% reduction of adenosine transport (at 100 μM), caused by the transport inhibitor Persantin, inhibited adenosine deamination by whole cells to about the same extent as transport, whereas adenosine phosphorylation was relatively little affected; thus in the presence of Persantin, transport and metabolism resembled that occurring at the low adenosine concentration. These and other results indicate that adenosine deamination is an event distinct from transport, which occurs only subsequent to adenosine's transport into the cell.
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  • 213
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have previously identified two stimulatory activities affecting blood cell maturation in PHA-stimulated human lymphocyte conditioned medium (PHA-LyCM). One was granulocyte-macrophage colony stimulatory activity (GM-CSA), and the other was T lymphocyte growth stimulatory activity (TL-GSA) in suspension culture. In this paper we have shown that although both activities can be produced from purified non-adherent human T lymphocytes, they are produced from two distinct subpopulations. The production of these activities was greatly enhanced by T cell mitogens. Both protein factors were relatively heat stable (56°, 30 minutes), were sensitive to trypsin treatment and were specific for primate blood cells. These two activities were fractionated by means of ammonium sulfate precipitation, Sephadex G-150 gel filtration, DEAE cellulose and Con A-Sepharose column chromatographies. MW of the major peak estimated from the elution volume of gel filtration in the presence of 0.5 M NaCl was 40,000 for GM-CSA and 13,000 for TL-GSA. Results from Con A-Sepharose column showed that while about 70% of TL-GSA was bound to Con A, less than 25% of GM-CSA was bound. These observations show that the majority of TL-GSA and GM-CSA were separable by these two conventional column chromatographic methods.
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  • 214
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    Journal of Cellular Physiology 101 (1979), S. 279-292 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Small (1 mm diameter) glass beads treated with acid and alkali provided a satisfactory substratum for the attachment and growth of normal and SV-40 transformed Balb/c 3T3 murine cells. Cells attached to the beads with similar, though slower kinetics as to flat glass surfaces, and spread and grew with their usual morphology; when detached by EGTA treatment, they left behind cellular substrate-attached material (SAM) which was similar electrophoretically to that obtained from tissue culture plastic. Because of their small size and rough etched surfaces, the beads have a large surface area and high adsorptive capacity, and so are a useful tool to isolate specific serum proteins adsorbed from the culture medium that may be important for cell attachment and spreading. The adsorbed serum proteins were solubilized with SDS and analyzed by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) under reducing and non-reducing conditions. They included all reduced species adsorbed to tissue culture plastic, and only small amounts of one other major protein extracted from a “bacteriological” polystyrene surface on which cells could not grow. Profiles of unreduced samples differed considerably. The profile of adsorbed proteins varied little with tiem (5 minutes-4 days), temperature (4°-37°C), pH (5-9), presence of the protease inhibitor PMSF, or serum concentration (0.1-10%). Much of the adsorbed protein, qualitatively similar to the SDS-extracted material, could be eluted with H2O or phosphate-buffered saline. Purified albumin and fibrinogen bound avidly to the beads; the material adsorbed from serum contained a large amount of albumin, however, little fibrinogen and no cold-insoluble globulin (as a 220 K protein) could be detected by Coomassie blue stained SDS-PAGE gels.
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  • 215
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    Journal of Cellular Physiology 101 (1979), S. 325-340 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Evidence is presented which suggests that a CHO-derived thymidine kinase (Tk) heterozygote, ts201, can reversibly inactivate the wild type Tk allele, and that this event may result in simultaneous inactivation of a linked allele, galactokinase (Glk). The clone ts201 was isolated as a revertant of a stable Tk- 5-bromodeoxyuridine (BrdU)-resistant mutant of CHO. The reacquired Tk activity differed from that of the wild type with respect to Km and heat resistance, supporting the contention that ts201 was genetically heterozygous (Tk+/-). At frequencies varying from 0.02-0.5, segregants of ts201 could be isolated by cloning in BrdU at 39°. These derivatives were phenotypically Tk- (by enzymology and by autoradiography of 3H-dT labeled cells), but after removal of BrdU, reacquired the Tk+ phenotype at frequencies varying randomly from clone to clone. From mutagenized populations of Ts201 two variants were isolated, 71t and 72c, by selection at 39° in 2-deoxygalactose (2-dgal). Resistance to 2-dgal has been correlated with a mutation in the gene for Glk, which is syntenic with that for Tk and evidence is presented suggesting that 71t and 72c are Glk+/-. Cloning efficiencies in doubly selective media and autoradiographic data showed that at 39° a coordination existed between the levels of Tk and Glk, which in 71t was inverse, and in 72c, direct. These data led to the hypothesis that pairs of linked alleles can be inactivated or re-expressed simultaneously. The inactivating effect was temperature-sensitive, since at 33°, the cloning efficiency in BrdU and in 2-dgal was very low.
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  • 216
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    Journal of Cellular Physiology 101 (1979), S. 359-359 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 217
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    Journal of Cellular Physiology 99 (1979), S. 37-42 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Tunicamycin, an antibiotic that inhibits protein glycosylation, elicited a rapid depletion of insulin binding activity at the surface of 3T3-L1 adipocytes. Disappearance of insulin receptors occurred more rapidly in the presence of tunicamycin than when protein synthesis was inhibited by cycloheximide and was accompanied by a diminution in sensitivity of the adipocytes to the acute effects of insulin and anit-insulin receptor antibody on hexose uptake and metabolism.
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  • 218
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    Journal of Cellular Physiology 99 (1979), S. 43-54 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: T98 and T98G are two related cell lines that were derived from a human glioblastoma multiforma tumor. T98G has almost twice as many chromosomes as T98, suggesting that it is a polyploid variant of T98. Three aspects of control of cellular proliferation were studied in T98 and T98G cells in comparison to WI-38 normal human diploid cells. WI-38 cells have the following properties: (1) they can undergo only a limited number of population doublings in vitro; (2) they cannot proliferate without anchorage; and (3) they become arrested in G1 phase under stationary phase conditions. T98 cells differ from normal cells in all three of these properties, as do many other transformed cell lines. However, the derivative of T98, namely T98G, expresses an unique combination of normal and transformed aspects of the control of cellular proliferation. T98G cells are like normal cells in that they become arrested in G1 phase under stationary phase conditions, yet they also exhibit the transformed characteristics of anchorage independence and immortality. Thus, T98G cells demonstrate that transformation to immortality and anchorage independence can exist without concomitant loss of the normal mechanism for G1 arrest in response to stationary phase conditions. This result supports the hypothesis that each of these three aspects of control of cellular proliferation can be altered independently. Partially transformed cell lines, such as T98G, should be useful for sorting out the biochemical changes associated with transformation in each of these aspects.
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  • 219
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    Journal of Cellular Physiology 99 (1979), S. 67-77 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have examined the kinetics of chick cell population aging in vitro using the percentage of labeled nuclei, the number of colonies formed from a low density inoculum and the number of cells/colony to monitor culture age. The results from these studies showed a gradual age-associated decline in each of the parameters which was first detected early in the culture lifespan and well in advance of changes in total cell number at confluency. Our results also indicated that each of the above parameters, in addition to the calendar time cells had been in culture, could be used to estimate the percentage of lifespan completed by the culture. A comparison of the methods used to estimate the remaining culture lifespan indicated that the percentage of labeled nuclei was the most accurate in describing cell age.
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  • 220
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Puromycin aminonucleoside selectively inhibits the synthesis of ribosomal RNA in human lung fibroblasts transformed by the oncogenic virus SV40. The mechanism of this inhibition was studied utilizing nuclei and nucleoli isolated from cells treated for 18 hours with 100 μg/ml of this compound. It was established that for a limited period of time nuclei and nucleoli isolated from the fibroblasts continue synthesis of RNA of size classes seen in intact cells, and that the inhibitory effect of aminonucleoside persists after isolation of these organelles. The inhibition was shown to be directed primarily to the activity of RNA polymerase I.Studies of the mechanism of this inhibition have indicated that the decreased rate of the polymerase reaction is not due to the impairment of the template function of nucleolar chromatin, and that unbound, as well as chromatin-bound, RNA polymerase I is present in both control and treated nucleoli. Analysis of the size distribution of the products of cell-free RNA synthesis showed that aminonucleoside pretreatment results in marked reduction in the synthesis of preribosomal 45S RNA, abnormal accumulation of 32S RNA, and reduced formation of mature ribosomal RNA species in the in vitro system. The data suggest that the inhibitory effect of aminonucleoside on ribosomal synthesis is due in part to a lower rate of transcription by RNA polymerase I of preribosomal RNA, and in part to its impaired maturation.
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  • 221
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    Journal of Cellular Physiology 99 (1979), S. 79-93 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Transmembrane electrical and pH gradients have been measured across human erythrocytes and peripheral blood lymphocytes using equilibrium distributions of radioactively labelled lipophilic ions, and of weak acids and weak bases, respectively. The distributions of methylamine, trimethylamine, acetic acid and trimethylacetic acid give calculated transmembrane pH gradients (pHe-pHi) for erythrocytes of between 0.14-0.21 for extracellular pH values of 7.28-7.16. The distributions of trimethylacetic acid, DMO and trimethylamine were determined for lymphocytes, establishing upper and lower limits of the calculated pH gradient over he external pH range of 6.7 to 7.7.Tritiated triphenylmethyl phosphonium ion (TPMP) and 14C-thiocyanate ion (SCN) equilibrium distributions were measured in order to calculate transmembrane electrical potentials, using tetraphenylboron as a catalyst to facilitate TPMP equilibrium. Transmembrane potentials of -7 to -10 mV were calculated from SCN and TPMP, respectively for red cells, and -35 to -52 mV respectively, in the case of lymphocytes. Distributions of TPMP and potassium ions were determined in the presence of valinomycin over a wide range of extracellular potassium concentrations for red cells and the calculated Nernst potentials for TPMP compared to the calculated potential using the Goldman equation for chloride and potassium ions. Distributions of TPMP, SCN and potassium ions were also determined for lymphocyte suspensions as a function of extracellular potassium and the calculated Nernst potentials for TPMP and SCN compared to the calculated potassium diffusion potential.
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  • 222
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    Journal of Cellular Physiology 100 (1979) 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 223
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    Journal of Cellular Physiology 100 (1979), S. 391-399 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Normal rat hepatocytes have been fused with highly differentiated rat hepatoma cells. Some of the hybrids express a physiologically significant level of activity of the urea cycle enzyme ornithine carbamoyltransferase (OCT), a liver-specific function not found in the hepatoma cells. These hybrids have 10% of the adult rat liver OCT specific activity, incorporate 3H-ornithine into protein arginine, and can be selectively grown in arginine-free medium supplemented with ornithine. Somatic cell hybridization of normal differentiated cells with highly differentiated neoplastic cells of the same tissue type may be useful as a general method for obtaining permanent cell lines with new tissue-specific phenotypes.
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  • 224
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    Journal of Cellular Physiology 100 (1979), S. 407-411 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This report strongly suggests that two compartments in Tetrahymena thermophila contain peptidase activity: the cytoplasm and the outer cell surface.Determinations of amino acid concentrations in the extracellular medium upon incubation of cells with peptides suggest that the surface-bound peptidase activity hydrolyses di- and tri-phenylalanine equally fast on a molar basis.Growth experiments designed to characterize the in vivo peptidase specificities showed that both T. thermophila and T. pyriformis can use L-leucyl-L-leucine, but not L-leucyl-D-leucine as a leucine donor. These results are independent of whether the cells form food vacuoles or not.
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  • 225
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    Journal of Cellular Physiology 100 (1979), S. 497-507 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A rapid reduction of cyclic nucleotide phosphodiesterase activity occurs after the replating of confluent cultures of BHK 21 c/13 fibroblasts into fresh medium. This reduction in activity depends on the density to which the cultures are reseeded and the concentration of serum in the medium. Enzyme activity in BHK cells is restored after 24 to 48 hours if cells are diluted into medium containing 10% fetal calf serum or 0.5% fetal calf serum supplemented with insulin (10-6 M), but not into 0.5% serum alone. The restoration in enzyme activity is blocked by cycloheximide or Actinomycin D.When BHK cells become quiescent by maintenance in 0.5% serum conditions for 48 hours, a rapid (15-60 minutes) increase in cyclic AMP phosphodiesterase activity occurs when 10% serum is added to the cultures. Enzyme activity is increased even further after 24 to 48 hours in the 10% serum. Cycloheximide or Actinomycin D do not affect the rapid increase in enzyme activity in response to serum, but completely inhibit the long term increase. In contrast to serum, insulin (10-8 to 10-6 M) has no short term effect, but does increase enzyme activity after 24 to 48 hours to levels comparable to those seen with addition of 10% serum. As is the case with serum, this long term effect of insulin on enzyme activity is prevented by inhibitors of protein and RNA synthesis.Kinetic analyses of cyclic AMP phosphodiesterase activity in homogenates of quiescent BHK cells indicate the presence of only high Km (≃ 20 μM) enzyme activity. Addition of serum or insulin to quiescent cells results in the appearance of apparent low Km enzyme activity in homogenates. Sucrose gradient analysis of BHK cells displays two forms of cyclic AMP phosphodiesterase enzyme activity: a 3-4 S form and 5-6 S form. In quiescent cells, the 5-6 form greatly predominates relative to the 3-4 form. Addition of serum to quiescent cells results in a rapid appearance of increased 3-4 S form enzyme activity. Insulin also increases the activity of this higher affinity 3-4 S enzyme form after 24 to 48 hours in culture. The functional significance of short and long term regulation of cyclic nucleotide phosphodiesterase(s) in cells is discussed.
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    Journal of Cellular Physiology 100 (1979), S. 531-538 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have previously shown that when resting 3T6 cells are serum stimulated in the presence of inhibitors of protein synthesis, poly(A)(+) mRNA content increases extremely rapidly relative to cells stimulated in the absence of drug. Poly(A)(+) mRNA content nearly doubles within two hours, but then remains constant for at least ten hours (Johnson and Meister, '77). In this report we show that continuous exposure to both serum and cycloheximide are required to maintain this elevated mRNA level. Removal of either leads to an equally rapid decrease in poly(A)(+) mRNA content. If cycloheximide is withdrawn at either two or ten hours following serum stimulation in the presence of the drug, allowing the rapid (〈 30 minutes) restoration of the rate of protein synthesis, we observe that poly(A)(+) mRNA content decreases within two hours to a level nearly equal to that found in resting cells prior to stimulation. If the drug is withdrawn but the serum stimulus is not, the rapid decrease in poly(A)(+) mRNA content is followed by an increase which is parallel to that which occurs in cultures stimulated in the absence of drug, but displaced from the latter by an interval approximately equal to the length of exposure of the drug. These results show that the mammalian cell is able to decrease as well as increase its content of poly(A)(+) mRNA in response to drug induced perturbations in the rate of protein synthesis. The changes in poly(A)(+) mRNA content occur extremely rapidly and may represent an attempt by the cell to correct the perturbation.
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  • 227
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    Journal of Cellular Physiology 100 (1979), S. 589-601 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Rous-sarcoma transformed BHK cells can be continuously cultured in a medium containing Eagle's Minimal Essential Medium, iron and biotin. The rate of cell multiplication increased when serine, or serine plus other non-essential amino-acids were added to the medium. With biotin deleted from the medium there is a reduction in DNA synthesis and most cells are blocked in G1.
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  • 228
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    Journal of Cellular Physiology 101 (1979), S. 49-55 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The role of hydrogen bonding in red cell aggregation induced by dextran was studied with the use of urea, an inhibitor for hydrogen bonding. In order to avoid hemolysis of red cells by the high concentration of urea, the studies were performed on human red cells hardened in glutaraldehyde. The degree of red cell aggregation at Hct = 45% was estimated by the use of a coaxial cylinder viscometer. The viscometric aggregation index (VAI) was calculated from viscosity values at shear rates of 52 sec-1 (ηH) and 0.05 sec-1 (ηL); VAI = (ηL-ηH)/ηH. Red cells with surface charge intact and with charge removal by neuraminidase treatment were studied. Urea at high concentrations, e.g., 6 M, significantly inhibited red cell aggregation induced by dextran. These findings indicate that hydrogen bonding plays an important role in dextran-induced red cell aggregation. An understanding of the nature of the forces involved in red cell aggregation serves to establish the physicochemical principles of cell-to-cell interactions induced by macromolecules.
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    Journal of Cellular Physiology 101 (1979), S. 67-75 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A comparison of the growth rates of established human lymphoid and tumor cell lines was performed in nutrient medium made hyperosmolal with mannitol, NaCl, or mixtures of NaCl and KCl at a constant Na/K ratio. It was found that considerably higher osmolalities were attained with mannitol than electrolytes before a reduction in the growth rate of the culture was observed. This suggests that mannitol and electrolytes affected the growth rate through different mechanisms. Mannitol uptake was studied with two of the cell lines and both cell lines were found to be permeable to mannitol. This eventually would have eliminated the osmolality gradient between the interior of the cell and the medium, and could explain why higher osmolalities were obtained with mannitol before the growth rate was effected. In addition, initial experiments showed that these cell lines may also be able to metabolize mannitol.
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    Journal of Cellular Physiology 101 (1979), S. 157-167 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Con A, a known T-cell mitogen, is also mitogenic for resident peritoneal macrophages. The stimulated cells morphologically resemble macrophages and are actively phagocytic. The concentration of con A (30 μg/ml) required to stimulate 3H-TdR incorporation is ten times that required for T-cell activation. Con A must be present throughout the entire culture period to produce the maximum effect, and con A-depleted supernatant fluids from con A-stimulated cells cannot replace the con A requirement. Stimulation of 3H-TdR incorporation occurs after a 48-hour lag period and is maximal on the fifth to seventh day of culture. At the peak of the response, 20-30% of the macrophages can be stimulated to incorporate 3H-TdR, but little or no increase in the total number of cells present in the culture occurs. This and pulse-chase experiments indicate that only a single cycle of replication occurs in the stimulated cells. Con A-responsive peritoneal macrophages appear to be a distinct subpopulation and might play a different role in the interaction with T cells and B cells in the immune response than the con A-non-responsive cells.
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    Journal of Cellular Physiology 101 (1979) 
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  • 232
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    Notes: Sugar deprivation of hamster fibroblasts (NILAbbreviations: ATP, ADP and AMP, adenosine 5′-tri-, di- and monophosphate respectively; CTP, CDP and CMP, cytosine 5′-tri-, di and monophosphate respectively; GTP, GDP and GMP, guanosine 5′-tri-, di- and monophosphate respectively; IMP, inosine 5′-monophosphate; Gal-1-P, α-D-galactose-1-phosphate; UDP-Gal, uridine 5′-diphosphogalactose; D-MEM, Dulbecco's modified Eagle's minimal essential medium; D-PBS, Dulbecco's phosphate-buffered saline (pH 7.2); NIL, a line of Syrian hamster fibroblasts; PyNIL, a polyoma virus-transformed line of NIL cells.) affected the steady state levels (pool sizes) of cellular acid soluble nucleotides in the following fashion; the pools of UTP, GTP and CTP decreased to a much greater extent than the cellular ATP pools, with the UTP pools undergoing the most dramatic reduction. Sugar deprivation of polyoma-transformed NIL cells (PyNIL) yielded even sharper decreases in the nucleoside triphosphate pools with relative changes similar to those of the untransformed cells. Inhibition of protein synthesis by cycloheximide, initiated at the onset of (and continued during) sugar deprivation, prevented the reduction in pool sizes and yielded values slightly higher than those observed for pool sizes in cells cultured in sugar-supplemented medium. Refeeding glucose to sugar-depleted hamster fibroblasts led to rapid increases (within 1 hour) in the UTP and CTP pools to levels well above the pool sizes observed in cells which were continuously cultured (16 hours) in sugar supplemented medium. Feeding NIL or PyNIL cells with fructose instead of glucose as the only hexose source did not appreciably affect any of the ribonucleoside triphosphate pool sizes. Measurements of hexose uptake by NIL and PyNIL cells under a variety of conditions suggest that hexose transport is not regulated by the total cellular pools of ATP or any of the other ribonucleoside triphosphates.
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    Journal of Cellular Physiology 101 (1979), S. 341-348 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Parathyroid hormone (PTH) is known to have a number of effects on bone tissue in vitro, including the stimulation of calcium release and the synthesis and turnover of hyaluronate. PTH-stimulated calcium release is inhibited by colchicine. Since hyaluronate may play a role in demineralization, calcium release into the media as a measure of bone resorption was correlated with the synthesis and secretion of 3H-glucosamine-labeled macromolecules. Newborn mice were labeled with 45Ca, and the calvaria removed and incubated in vitro in media containing 3H-glucosamine. Addition of colchicine to the culture media inhibited the release of 45Ca into the media while stimulating the synthesis and secretion of 3H-glucosamine labeled macromolecules. DEAE-cellulose chromatography resolved the labeled macromolecular material into four peaks, of which the third peak containing hyaluronate demonstrated approximately twice the amount of radioactivity. PTH stimulation of calcium release was inhibited likewise by colchicine, while 3H-glucosamine incorporation into labeled macromolecules was stimulated. Short term labeling studies emphasized the marked stimulatory effect that both PTH and colchicine have on the incorporation of 3H-glucosamine into hyaluronate. PTH stimulated the incorporation of 35S-sulfate, while colchicine markedly inhibited its incorporation into non-dialyzable material. Both PTH and colchicine inhibited protein synthesis. Based on the observations, colchicine appears to stimulate the synthesis and secretion of hyaluronate and alter a number of metabolic pathways. Hyaluronate does not appear to be directly involved in the demineralization process.
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    Notes: The objective of this study was to determine the points in the cell cycle at which normal and transformed cells become arrested as a result of polyamine deprivation. Treatment of normal (human fibroblast line PA2 and mouse 3T3) and transformed (CHO, HeLa and SV3T3) cells with methylglyoxal bis-(guanyl-hydrazone) resulted in a significant decrease in the levels of spermidine and spermine which was associated with an inhibition of growth. Examination of the prematurely condensed chromosomes (PCC) of the polyaminedepleted cells, revealed that normal fibroblasts were preferentially arrested in early G1 phase while a majority of cells in the transformed lines were blocked in S phase. A close examination of the PCC of the transformed cells indicated a significant decrease in the number of DNA replication sites suggesting that polyamines have an important role in DNA chain initiation.
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  • 235
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    Journal of Cellular Physiology 98 (1979), S. 469-473 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cholera toxin was used in an attempt to inhibit epidermal growth factor stimulated 3T3 cell division. Instead, cholera toxin alone at low concentrations (10-10 M), was able to stimulate cell division and could augment EGF stimulated cell division. The mitogenic effect of cholera toxin can occur despite a dramatic increase in the intracellular levels of cAMP in 3T3 cells. Cholera toxin stimulated mitogenesis could not be mimicked by choleragenoid, the binding but inactive subunit of cholera toxin, or by other agents which elevate cAMP levels in 3T3 cells.
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    Notes: A mutant (A204) of Chinese hamster ovary cells (CHO-K1), which is deficient in dihydroorotate (DHO) dehydrogenase (E.C. 1.3.3.1) activity, has been isolated by a replica plating procedure. The mutant does not show a requirement for exogenously added pyrimidines. Examination of intact cells shows that the mutant accumulates a large amount of carbamyl aspartate and is markedly but not totally deficient in biosynthesis of orotate from earlier precursors of pyrimidine biosynthesis, including aspartate and dihydroorotic acid, when compared to wild-type cells. Analysis of cell-free extracts of mutant and wild-type cells shows that the mutant is deficient in DHO dehydrogenase activity, possessing ca. 5% of the wild-type activity. This evidence leads to the conclusion that this mutant, A204, is in fact partially deficient in DHO dehydrogenase, and that in these cells it is this enzyme which carries out the fourth step of de novo pyrimidine biosynthesis.
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    Journal of Cellular Physiology 98 (1979), S. 475-481 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ornithine aminotransferase catalyzes the reversible transamination of L-ornithine to δ1-pyrroline-5-carboxylate, the immediate precursor of proline. The direction and flux through this pathway in mammalian cells has not been established. Glutamate has generally been considered to be the most important precursor for proline biosynthesis, but recent studies in xiphoid cartilage indicate that a significant fraction of cellular proline is derived from ornithine. Using newly isolated mutant Chinese hamster ovary cells with defined defects in the proline biosynthetic pathways, we now have established that cells can grow at a maximal rate with ornithine as the sole source of proline. Furthermore, we have measured the rate of proline formation from ornithine (1.6 nmol/h/106 cells). Future studies with these mutant Chinese hamster ovary cells may offer insight into the regulatory mechanism which coordinates proline biosynthesis from ornithine and glutamate.
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    Journal of Cellular Physiology 98 (1979), S. 491-502 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The removal of serum from the medium of ovarian granulosa cells in exponential or confluent stages of growth results in a rapid and pronounced decrease in the rate of transport of the non-metabolizable amino acid, α-aminoisobutyric acid. This decrease is rapidly and completely reversed by the addition of serum. The decrease and its reversal are insensitive to inhibitors of RNA and protein synthesis and are unaffected by a number of other metabolic inhibitors. The serum requirement cannot be replaced by peptide hormones known to stimulate cell division and secretion by these cells. These data are consistent with a model of post-translational control of AIB transport by a high-molecular-weight component of serum.
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    Journal of Cellular Physiology 98 (1979), S. 483-489 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Treatment of CHO cells with drugs which are known to increase membrane lipid fluidity reduced the cells' ability to adhere to protein coated substrates. The concentrations of local anesthetics, nonionic detergents or aliphatic alcohols required to reduce CHO cell adhesion by 50% were similar to those reported to block nerve conduction, indicating that these drugs can affect the membrane at physiologically significant concentrations. Nonionic detergents and aliphatic alcohols, but not local anesthetics, caused increases in the fluidity of CHO plasma membranes (measured by fluorescence polarization) at concentrations which inhibited cell adhesion. The adhesion versus temperature profile had a sigmoidal shape, suggesting that a temperature dependent cooperative process such as a lipid phase transition, might be involved. However, the temperature profile for CHO membrane fluidity manifested no discontinuities, indicating the absence of any discrete phase transitions of the lipid matrix. This observation, coupled with the result that the inhibition of CHO cell adhesion produced by low temperatures was not relieved by drugs which can increase membrane fluidity, suggests that the reduced adhesion seen at low temperature is probably not due to reduced lipid fluidity.
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    Journal of Cellular Physiology 98 (1979), S. 503-513 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Components of the renin-angiotensin system were studied in established cell culture lines of 3T3 and SV3T3 mouse fibroblasts. The renin content in 3T3 cells was significantly higher than in virus-transformed SV3T3 cells. With time after infection, renin decreased in Simian virus 40 transformed cells, while it increased steadily in mock-infected 3T3 cells. In contrast to renin, angiotensinase activity was higher in SV3T3 cells.Angiotensin II stimulated cell proliferation in 3T3 mouse fibroblasts and decreased their renin content in a dose-related manner. In contrast, saralasin, an angiotensin receptor antagonist, inhibited cell growth in 3T3 and SV3T3 cells and caused an increase of cellular renin concentration. The angiotensin fragments angiotensin (2-8) heptapeptide and angiotensin (4-8) pentapeptide had no effect on cell growth. A significant negative correlation was found between cell proliferation and renin levels in 3T3 and SV3T3 cells irrespective of the treatment.Our results indicate (1) that angiotensin II may be involved in cell growth regulation, (2) that a negative feedback exists between angiotensin II added and intracellular renin content, and (3) that virus infection causes a decrease in intracellular renin synthesis, while non-specific angiotensinase activity is increased under this condition.
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    Journal of Cellular Physiology 100 (1979), S. 127-138 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Previous studies on the synthesis and function of the protein synthetic machinery through the growth cycle of normal cultured hamster embryo fibroblasts (HA) were extended here to a series of four different clonal lines of polyoma virus-transformed HA cells. Under our culture conditions, these transformed cells could enter a stationary phase characterized by no mitotic cells, very low rates of DNA synthesis, and arrest in post-mitotic pre-DNA synthetic state. Cellular viability was initially high in stationary phase but, unlike normal cells, transformed cells slowly lost viability.The rate of protein synthesis in the stationary phase of the transformed cells fell to 25-30% of the exponential rate. Though this reduction was similar to that seen in normal cells, it was accomplished by different means. The specific reduction in the ribosome complement per cell to values below that of any cycling cell seen in normal cells, was not seen in any of the transformed lines. This observation, which implies a loss of normal control of ribosome synthesis through the growth cycle after transformation, was confirmed in normal Chinese hamster embryo fibroblasts and transformed CHO cell lines. Normal control of ribosome synthesis was restored in L-73 and LR-73, growth control revertants of one of the transformed CHO lines. The transformed lines reduced their protein synthetic rates in stationary phase either by a greater reduction in the proportion of functioning ribosomes than that seen in normal cells or by a decrease in the elongation rate of functioning ribosomes; the latter effect was not seen in the normal cells.A model for growth control of normal cells and its derangement in transformed cells is presented.
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    Journal of Cellular Physiology 100 (1979), S. 139-146 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Benzo[a]pyrene-transformed Balb 3T3 cells (BP3T3) exhibit “normal” growth controls at low concentrations of serum. Epidermal growth factor (EGF) stimulates DNA synthesis and cell division in both Balb 3T3 and BP3T3 cells at physiological concentrations. The growth response of BP3T3 cells to EGF is qualitatively the same as that of 3T3 cells, however, the transformed cells have a lower quantitative requirement. Both 3T3 and BP3T3 cells show a density-dependent response to EGF, but the shift in the dose response curve for BP3T3 cells at high cell density is smaller than that seen for 3T3 cells. One cause of the restricted growth of 3T3 cells at high cell density compared with BP3T3 cells in the increased concentration of growth factor needed for stimulation of 3T3 cells at higher cell densities. A lower rate of depletion of other growth factory by BP3T3 cells may also explain the smaller effect of cell density on the EGF response of these cells.
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    Journal of Cellular Physiology 100 (1979), S. 159-168 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Plasma membranes isolated from normal and RSV transformed chick embryo fibroblasts were phosphorylated in vitro using endogenous protein kinase and ATP (γ32P) and the labeled phosphoproteins were analyzed by SDS-PAGE. A number of protein phosphorylation changes were observed following transformation, however in most cases they were relatively small quantitative differences. The four major changes were in proteins of 47,000, 58,000, 75,000 and 135,000 daltons. Decreased phosphorylation of the 47,000 dalton polypeptide was found in transformed cell membranes but this alteration was shown to be due to differences in cell growth rather than transformation. Increased phosphorylation of the 75,000 dalton protein was at least partially related to virus infection. However, increased phosphorylation of the 58,000 and 135,000 dalton polypeptides were entirely transformation specific.
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    Journal of Cellular Physiology 99 (1979), S. 125-137 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cultured cells of Microtus agrestis, the common field vole, perform unscheduled DNA synthesis after UV irradiation. They respond to incubation with a DNA synthesis inhibitor (1-β-D-arabinofuranosylcytosine) following UV in ways typical of cells capable of excision repair, with reduced survival and an accumulation of breaks in pre-existing DNA.Microtus cells irradiated with UV in a quiescent pre-S-phase state are more sensitive to UV than are proliferating cells, in terms of survival. Adding DNA precursors (deoxyribonucleosides), and - in the case of proliferating cells - growing in complete rather than dialysed serum, enhance UV survival.Quiescent cells show a higher rate of endonucleolytic incision of DNA after UV than do proliferating cells.The balance between incision (producing single-strand DNA breaks) and repair DNA synthesis (leading to rejoining of breaks) is shifted by the addition of deoxyribonucleosides, which suggests that DNA precursor supply is a rate-limiting factor in repair. The lower survival of quiescent cells (in the absence of added deoxyribonucleosides) may be due to insufficient precursor supply to meet the demands of the high incision rate.
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The isolation and characterization of a mutant murine T-cell lymphoma (S49) with altered purine metabolism is described. This mutant, AU-100, was isolated from a mutagenized populatio of S49 cells by virtue of its resistance to 0.1 mM 6-azauridine in semisolid agarose. The AU-100 cells are resistant to adenosine mediated cytotoxicity but are extraordinarily sensitive to killing by guanosine.High performance liquid chromatography of AU-100 cells extracts has demonstrated that intracellular levels of GTP, IMP, and GMP are all elevated about 3-fold over those levels found in wild type cells. The AU-100 cells also contain an elevated intracellular level of pyrophosphoribosylphosphate (PPriboseP), which as in wild type cells is diminished by incubation of AU-100 cells with adenosine. However AU-100 cells synthesize purines de novo at a rate less than 35% of that found in wild type cells.In other growth rate experiments, the AU-100 cell line was shown to be resistant to 6-thioguanine and 6-mercaptopurine. Levels of hypoxanthine-guanine phosphoribosyltransferase (HGPRTase) measured in AU-100 cell extracts, however, are 50-66% greater than those levels of HGPRTase found in wild type cell extracts. Nevertheless this mutant S49 cell line cannot efficiently incorporate labeled hypoxanthine into nucleotides since the salvage enzyme HGPRTase is inhibited in vivo.The AU-100 cell line was found to be 80% deficient in adenylosuccinate synthetase, but these cells are not auxotrophic for adenosine or other purines. The significant alterations in the control of purine de novo and salvage metabolism caused by the defect in adenylosuccinate synthetase are mediated by the resulting increased levels of guanosine necleotides.
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  • 246
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    Journal of Cellular Physiology 99 (1979), S. 153-158 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: When Chinese Hamster Ovary (CHO) cells, incubated in serum-free medium, are exposed to gonadotropins a transient increase in the intracellular concentration of cyclic AMP is observed. Maximum accumulation of cyclic AMP is noted 30 minutes after addition of either human chorionic gonadotropin (hCG) or follicle stimulating hormone (FSH). Within one to two hours after hormone addition, the intracellular concentrations of cyclic AMP have returned to basal levels. The enhancement of intracellular cyclic AMP levels by hCG is hormone concentration dependent, with maximal stimulation observed at 10 μg/ml hCG.The exogenous addition of gonadotropins also slows the growth rate of CHO cells. This effect on growth seems to be mediated through cyclic AMP since the growth rate of a mutant of CHO cells defective in the catalytic subunit of cyclic AMP dependent protein kinase is only slightly decreased.
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  • 247
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    Journal of Cellular Physiology 99 (1979) 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 248
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    Journal of Cellular Physiology 99 (1979), S. 183-190 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Exogenous diamines and polyamines added to rat hepatoma (HTC) cells in culture rapidly decrease ornithine decarboxylase (ODC) activity. Previous evidence has suggested that these amines act either at the level of blocking new enzyme synthesis or by the induction of a non-competitive protein inhibitor, termed antizyme, which complexes with ODC to form an inactive complex. With the use of HMOA cells, a recently cloned rat hepatoma cell line that has a greatly stabilized ODC, it has been possible to demonstrate that 10-5 M of exogenous putrescine blocks the increase in ODC activity, but unlike in the parent HTC cell line, without induction of the antizyme or formation of any inactive ODC-antizyme complex. However, complete blockade of ODC at 10-2 M putrescine is effected by induction of antizyme and formation of the ODC-antizyme complex, as now evidenced by the isolation of the active enzyme and antizyme components after Sephadex column chromatography in the presence of 250 mM NaCl. These findings indicate clearly that two polyamine-regulatory mechanisms for ODC exist and are separable in this cell line.
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  • 249
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    Journal of Cellular Physiology 100 (1979), S. 215-225 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A procedure is described in which animal cells grown in culture on a dish are rapidly rinsed in situ with 0.25 M sucrose solutions for subsequent measurement of total, intracellular and rapidly exchangeable Na+, K+, Mg2+ and Ca2+ by atomic absorption spectrophotometry. Repeated rinses with CO2-free (pH ∼7) 0.25 M sucrose solution produced essentially no loss of cellular protein or cations. One 10-second rinse with CO2-saturated (pH 4) 0.25 M sucrose solution removed a rapidly proton exchangeable cellular cation fraction which is interpreted as being externally (membrane) bound. Rinses with physiological electrolyte solutions are shown to produce loss of cellular protein as well as displacement of surface exchangeable cations. Thus, isotonic sucrose solution is more satisfactory than electrolytic media for rinsing cultured cells prior to measurement of cellular cations. The technique employing sucrose rinse media is very rapid and reproducible and permits measurement of total, intracellular or surface bound Na+, K+, Mg2+ and Ca2+ in the same sample.
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  • 250
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    Journal of Cellular Physiology 100 (1979), S. 199-213 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: AKR-2B mouse embryo cells undergoing the serum-stimulated transition from a quiescent to a proliferating state exhibit an increase in the rate of hnRNA synthesis which appears to be mediated through an increase in the actual number of RNA polymerase II molecules. α-Amanitin, administered early in the prereplication interval following stimulation, effectively inhibits hnRNA synthesis, polysomal mRNA accumulation, polyribosome formation, and subsequent DNA synthesis, and cell division. Unexpectedly, α-amanitin treatment also produces almost complete inhibition of the synthesis of 45SrRNA precursor and the increase in accumulation of cytoplasmic rRNA following serum stimulation. In order to determine whether the inhibition of new ribosomal synthesis might in itself be sufficient to prevent serum-stimulated DNA synthesis, the effects of 5-fluorouridine (5-FU), a specific inhibitor of 45SrRNA processing, were investigated. If added within eight hours following serum stimulation, 5-FU was found to completely inhibit subsequent DNA synthesis. These results suggest that quescent AKR-2B cells do not contain a sufficient excess of ribosomes to support the synthesis of proteins which are required for DNA synthesis in response to serum growth factors. Furthermore, an early polymerase II mediated synthesis of mRNA (s) coding for some factor(S) necessary for ribosomal gene transcription may be an essential step in the serum-stimulated synthesis of new ribosomes.
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  • 251
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: Epidermal growth factor (EGF) stimulates the growth of both benzo[a]pyrene-transformed Balb 3T3 cells (BP3T3) and untransformed Balb 3T3 cells. We describe here the binding, internalization, and degradation of [125I]-EGF by BP3T3 cells and 3T3 cells. Binding of [125I]-EGF reaches a maximum after 45 to 90 minutes incubation at 37°C. In both BP3T3 and 3T3 cells the extent of EGF binding required to stimulate DNA synthesis is density dependent; sparse cultures require a 15-30% occupancy to elicit a maximal response whereas dense cultures require a 70-85% occupancy. At physiological concentrations the total binding of [125I]-EGF to 3T3 cells is higher than to BP3T3 cells, and this difference increases at higher cell densities. The rate of degradation of [125I]-EGF is directly proportional to the total [125I]-EGF binding in each cell type. This supports the hypothesis that one cause of the diminished serum requrement of BP3T3 cells is a reduced rate of utilization of serum growth factors.
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  • 252
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    Journal of Cellular Physiology 100 (1979), S. 273-277 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mitogenic activity is present at a variety of sites in the central nervous system. A growth factor was purified from neonatal bovine spinal cord. It has a pI of 9.5-9.8 and a molecular weight of about 11,000 daltons. Spinal cord growth factor is a basic polypeptide that is inactivated by extremely acid or basic conditions. Its mobility on SDS polyacrylamide gels suggests that this factor is different from pituitary FGF and brain FGF-1.
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  • 253
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    Journal of Cellular Physiology 100 (1979), S. 239-250 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The preincubation of rabbit neutrophils with the chemotactic factor F-Met-Leu-Phe and the subsequent addition of cytochalasin B has previously been shown to induce a time, concentration and calcium dependent loss of secretory responsiveness in neutrophils. This has been termed desensitization. The results reported here first confirm that lysosomal enzyme release from neutrophils will still occur in the absence of extracellular calcium. In addition, a time dependent decrease in the magnitude of the cytochalasin B induced influxes of 45Ca and 22Na was found upon preincubation with F-Met-Leu-Phe. In the presence of extracellular Ca2+, this decrease in ionic responsiveness reaches a maximum by five minutes preincubation with F-Met-Leu-Phe. In the absence of added extracellular Ca2+ an initial and rapid (〈1 minute) loss of ionic responsiveness is followed by partial recovery as the length of the preincubation with the chemotactic factor is increased from one to five minutes. These changes in ionic responses correspond exactly to the changes in secretory behavior of the neutrophils. Desensitization can thus be explained on the same ionic basis as that underlying the secretory response of the neutrophils. In addition, these results provide information about the sequence of events involved in the cytochalasin B and chemotactic factor induced release of lysosomal enzymes in neutrophils.
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  • 254
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    Journal of Cellular Physiology 100 (1979), S. 251-261 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Sodium butyrate and hydroxyurea, effective inhibitors of DNA synthesis in HeLa cells, cause these cells to produce increased levels of the ectopic glycopeptide hormones human chorionic gonadotropin (hCG), follicle stimulating hormone (FSH), and free α chains for these hormones. The objective of this study was an assessment of the role of modulation of cell cycle events in the action of these two chemical agents. A variety of experimental approaches was employed to obtain a clear view of the drugs' effects on cells located initially in all phases of the cell cycle. Cells in early G1, G2, or M phase at time of addition of either inhibitor were not arrested at early time points, but by 48 hours became collected at a location characteristic for each drug, near the G1-S phase boundary. Flow microfluorometry (FMF) and thymidine labeling index revealed that butyrate-treated cells arrested late in G1 phase very close to S phase, while hydroxyurea-blocked cells continued to early S phase. Both inhibitors prevented cells originally in S phase from reaching mitosis. S cells exposed to hydroxyurea were killed by 48 hours, but those growing in 5 mM butyrate progressed to the end of S or G2 phase where they became irreversibly arrested although not removed from the monolayer. Analysis of the cell cycle location and viability of each subpopulation resulting from 48 hour exposure to butyrate or hydroxyurea is important for the study of the function of each cellular subset. Treatment of HeLa cells with lower concentrations of butyrate (1 mM) resulted in slowed yet exponential growth. Fraction labeled mitosis (FLM) analysis shows that this is a result of prolongation of the G1 phase.
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  • 255
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    Journal of Cellular Physiology 100 (1979), S. 263-272 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Change in division capability as a phenotypic expression of cellular transformation was investigated by using one of the temperature-sensitive (ts) mutants of the polyoma virus-transformed cell line, the 121-6-5 cells of BALB/3T3. When contact -inhibited cells were treated with hyaluronidase at 39°C, a single round of cell division was induced after which cell growth was inhibited by cell density. However, if the cells were incubated at 35°C, after the enzyme treatment, density-inhibition block disappeared and the cells entered a second division. This indicates that the release of cells from density-inhibition depends on the low temperature incubation. The ability of cells to complete a second division was examined by shifting the cells from 39°C to 35°C during different phases of the first division cycle after the enzyme-treatment. A 6-hour incubation of S phase cells at 35°C resulted in a second cycle of division, while the 24-hour incubation of G1 cells at 35°C did not induce a second round of division. These results suggest that expression of the transformed phenotype in 121-6-5 cells is clearly dependent upon both the temperature and the phase of the division cycle.
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  • 256
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    Journal of Cellular Physiology 98 (1979), S. 59-71 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cellular resistance to the cytotoxic purine analogues 8-azaguanine (AG) and 6-thioguanine (TG) is usually mediated by a mutation leading to the loss or reduction in hypoxanthine phosphoribosyltransferase (HPRT) activity. However, stable AG-resistant variants have often been shown to contain wild-type levels of HPRT, while cellular resistance to TG is always accompanied by a profound deficiency in HPRT activity. Such AG-resistant, HPRT-positive cells are still sensitive to TG. To investigate the basis of this differential sensitivity, we examined the inhibition of the HPRT activity by AG and TG in whole cells, in cell-free extracts, and with purified mouse HPRT. In addition, the relative incorporation and utilization of AG and TG by L929 cells were determined under a variety of culture conditions.Results show that, compared to TG, AG is generally a very poor substrate for HPRT. Incorporation of radioactive AG by HPRT-positive cells was extremely sensitive to the free purine concentrations in the medium, so that under the usual culture conditions employing undialyzed serum, cellular uptake and utilization was minimal even when relatively high levels of AG were present. In contrast, the incorporation of radioactive TG was comparable to that of a natural substrate, hypoxanthine. These results indicate that the differential cellular sensitivity to AG and TG is due to the difference between these two guanine analogues as substrates of HPRT. Additional data indicate also that cellular resistance to TG is mediated exclusively by HPRT deficiency, but resistance to very high levels of AG may result through at least two other mechanisms not involving HPRT deficiency. These observations may help resolve some of the conflicting data in the literature, and demonstrate that TG is a better selective agent for the HPRT-deficient phenotype.
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  • 257
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    Journal of Cellular Physiology 98 (1979), S. 95-105 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Human lymphocytes were equilibrated for 48 hours over a wide range of external potassium levels, and their contents of potassium, sodium, and water determined. As external potassium rose from zero, cell potassium rose steeply in a sigmoidal fashion, reached half-saturation at 0.4 mM external potassium, and then saturated at 129 mmoles/kg cells. The saturable cell potassium exchanged mole-for-mole with sodium. Analysis of the saturable components by a statistical-mechanical adsorption model demonstrated a cooperative interaction between sites determining equilibrium potassium-sodium distribution. Superimposed upon the saturable fraction of cell potassium was a smaller one that was non-saturable with increasing external potassium to at least 64 mM, and that, when expressed as mmoles/liter cell water, existed in a ratio to external potassium of 0.6. The results strongly support the association-induction hypothesis, which predicts a small non-saturable component of ions determined by exclusion from oriented cell water and a cooperative interaction between sites throughout the cell that associate with potassium or sodium.
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  • 258
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: A transplantable methylcholanthrene-induced fibrosarcoma of female BALB/c mice (the MC-2 fibrosarcoma) was dissociated by combined mechanical and enzymatic means, then fractionated by isopycnic centrifugation in linear albumin gradients.In some experiments recovered cells were both cultured in soft nutrient agar and inoculated subcutaneously into syngeneic recipients. In these experiments a highly significant correlation was observed between subsequent colony number and rapid growth phase tumor size suggesting identity of clonigenic and tumorigenic cells.It was consistently found that clonigenic cells were markedly depleted from the low density extremes of the cell density distribution profiles suggesting that the low density neoplastic cells had irreversibly left the growth fraction.With increasing tumor age, sequential studies showed that both total and clonigenic cell density distribution profiles were variable, showing no obvious trend, suggesting that in the age (13-35 days) and size (2-8 g) range studied growth fraction changes had little selective effect on cells of any specific density. These results imply that a marked selective depletion of low density clonigenic cells (or selective accumulation of low density non-proliferative cells) must mainly occur during an earlier phase of tumor growth. Studies on several other murine solid tumors also showed maximal depletion of clonigenic cells from the least dense fractions, suggesting that this situation may be common.
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  • 259
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    Journal of Cellular Physiology 99 (1979), S. 239-246 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A variant of murine L5178Y lymphoma resistant to procaine hydrochloride (PH) was selected by exposing the cells to gradual increments of PH in the growth medium until the cell grew exponentially in the presence of 1.5 mM PH. Using cinephotomicrography, it was observed that the majority of cells that initially succumbed to PH failed to undergo successful mitosis. With respect to chromosomal, cell size distribution and flow microfluorometric analyses, the PH-resistant cells are very similar to a spontaneous tetraploid cell line (R1T) previously cloned. The isolated cells, designated R1/P, were also found to be cross-resistant to analogues of PH, namely, lidocaine, tetracaine and dibucaine. The naturally-occurring tetraploid cell line (R1T) was also found to be more resistant to local anesthetics, although not to the same extent as R1/P cells. Since the enzyme that hydrolyzes procaine appears to be absent in all these lymphoid cell lines, the difference in resistance does not appear to depend on differences in the ability of these cells to remove the agent. It is suggested that an alteration in the structure and/or function of the plasma membrane in R1/P cells have rendered them either less sensitive to the membrane-perturbing effects of the local anesthetics or less permeable to local anesthetics molecules. The ability of local anesthetics to affect membranes and cytoskeleton structures may play a role in the genesis and/or selection of these cell variants.
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    Journal of Cellular Physiology 99 (1979), S. 261-277 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cultured Friend murine erythroleukemia cells (Friend cells) are induced to undergo erythroid differentiation when grown in the presence of dimethylsulfoxide (DMSO) and other compounds. The effects of unifilar substitution of bromouracil (BU) for thymidine in the DNA (BU-DNA) of Friend cells were examined. Cells were grown in the presence of 5-bromodeoxyuridine (BrdU) for one generation, then centrifuged and resuspended in medium containing DMSO without BrdU. These cells exhibited a delay in the appearance of heme-producing, benzidine-reactive (B+) cells and a decreased rate of cell proliferation in comparison to the control not containing BU-DNA. A transient inhibition of entry into S phase was observed when control cells or cells containing BU-DNA were grown in the presence of DMSO for 10 to 20 hours. This transient inhibition was increased in the BrdU culture. Thus, BU-substitution in Friend cells alters other cellular functions in addition to erythroid differentiation. The rate of increase in the percent of cells committed to differentiate (those forming B+ colonies in plasma clots) was similar in the BrdU and control cultures until 40 to 50 hours. After this time, a delay in the appearance of committed cells was observed in the BrdU culture. The effect of BrdU on the appearance of B+ cells was more pronounced and occurred earlier than its effect on the rate of commitment. Therefore, the delay in the appearance of B+ cells in the BrdU culture was due primarily to perturbation of post-commitment events such as the accumulation of hemoglobin.We also examined the effect on growth and differentiation after BrdU was incorporated during different intervals of S phase in cells synchronized by centrifugal elutriation or by double thymidine block and hydroxyurea treatment. The delay in the appearance of B+ cells and inhibition of cell proliferation were only observed when BrdU was incorporated in the first half of S phase. BrdU (10 μM) had no effect on growth or differentiation when present during late S or G1 and G2. These results, using two very different methods to achieve cell synchrony, indicate that the effects of BrdU on growth and differentiation described above are due to its incorporation into DNA sequences replicating during early S.
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    Journal of Cellular Physiology 99 (1979), S. 279-285 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Somatic cell hybrids between either normal human fibroblasts, phenotypically normal mouse fibroblasts or mouse peritoneal macrophages and HT1080 human diploid fibrosarcoma cells were studied for their ability to form tumors in nude mice. The results of this study indicate that tumorigenic behavior is expressed as a dominant trait in both human-human and mouse-human hybrid cells.
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    Journal of Cellular Physiology 99 (1979), S. 287-301 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ability to synthesize inosinetriphosphate was demonstrated in blood cells as well as in a variety of tissue extracts in spite of the presence of ITP pyrophosphohydrolase. At the expense of having sub-optimal conditions, an assay system was selected that completely repressed the hydrolyzing enzyme, thus permitting the accumulation of ITP.In an attempt to define the biosynthetic pathway of ITP, and since guanylate kinase has been implicated in the formation of ITP, the rate of synthesis of ITP and GTP in cell extracts was compared.The comparison of the specific activities of the [14C]-labeled hypoxanthine and guanine moieties of the inosine and guanosine phosphates formed during incubation with [8-14C]-inosine and [8-14C]-guanosine respectively, revealed striking differences in the relative rates of isotope incorporation. Tentative mechanisms are proposed to explain these differences.The data obtained thus far does not discard the possibility that ITP may be formed by stepwise phosphorylation and (or) by direct pyrophosphorylation of IMP.
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    Journal of Cellular Physiology 99 (1979), S. 313-318 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effect of insulin on hexose transport in cultured human skin fibroblasts.Studies were carried out on cultures of human skin fibroblasts to explore the effect of insulin on hexose transport in serum-starved monolayers. Insulin (100 mU/ml) stimulated 2-deoxy-D-glucose transport (30% above control values) after 30 minutes exposure time, the response being similar up to four hours exposure to insulin. In several experiments (n = 22) employing three cell strains, insulin (100 mU/ml) exposure led to variable stimulation of 2-deoxy-D-glucose transport (an average of 37% above control values, with a range of 0 = 120%). The insulin-induced stimulation of 2-deoxy-D-glucose transport showed a dose dependency with increasing amounts of insulin, the response being maximal at an insulin concentration of 100 mU/ml. Kinetic analysis of 2-deoxy-D-glucose transport showed that insulin addition resulted in a slight change in the transport Km (3.13 to 4.06 mM) and a 1.8-fold increase in the transport Vmax (17.6 nanomoles/mg protein/min to 32.1 nanomoles/mg protein/min). Insulin also stimulated the transport of 3-0-methyl-D-glucose while the hexokinase activity of the cells was not affected. Further, this insulin-induced stimulation of sugar transport was not blocked by cycloheximide. The results indicate that insulin stimulated the stereospecific carrier-mediated of hexose transport in cultured human skin fibroblasts.
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    Journal of Cellular Physiology 99 (1979), S. 303-312 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A preliminary investigation was carried out to determine how conditional lethal mutants affected in particular aminoacyl-tRNA synthetases may be used to study the role of tRNA charging levels in protein synthesis. The relationship between rate of protein synthesis and level of histidyl-tRNA in wild-type cultured Chinese hamster ovary cells was determined using the analogue histidinol to inhibit histidyl-tRNA synthetase activity. This response was compared with that obtained using a mutant strain with a defective histidyl-tRNA synthetase that phenotypically shows decreased rates of protein synthesis at reduced concentrations of histidine in the growth medium. The approach used was based on measuring the histidyl-tRNA levels in live cells. The percentage charging was estimated by comparing [14C]histidine incorporated into alkali-labile material in paired samples, one of which was treated with cycloheximide, five minutes before terminating during the incubation, to produce maximal aminoacylation. Wild-type cells under histidinol inhibition exhibited a sensitive, sigmoidal relationship between the level of histidyl-tRNA and the rate of protein synthesis. A decrease in the relative percentage of acylated tRNAHis from 46% to 35% elicited a large reduction in the rate of protein synthesis from 90% to 30% relative to untreated cells. An unpredicted result was that the relationship between protein synthesis and histidyl-tRNA in the mutant was essentially linear. High acylation values for tRNAHis were associated with rates of protein synthesis that were not nearly as high as in wild-type cells. These findings suggest that the charging levels of tRNAHis isoacceptors could play a regulatory role in determining the rate of protein synthesis under conditions of histidine starvation in normal cells. The mutant appears to be a potentially useful system for studying the pivotal role of tRNA charging in protein synthesis, assuming that the altered response in the mutant is caused by its altered synthetase.
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    Journal of Cellular Physiology 99 (1979), S. 319-326 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: It is demonstrated here that cells in a suspension culture of an established mammalian cell line release non-dialyzable factors into their growth medium. These factors are capable of promoting the adhesion and spreading of these cells on a generally non-attachable substratum and also promote spreading on an adhering substrate. Evidence in presented which demonstrates that the spreading promotion activity of the conditioned medium is dependent on the cell density of the culture from which it was derived. Dilution of the conditioned medium results in a proportionate dilution of the spreading promotion activity. The results clearly demonstrate that the production of this spreading promotion factor is continued even in the absence of cell to substrate attachment.
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    Journal of Cellular Physiology 99 (1979), S. 327-331 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effect of the presence of nerve extracts on the development of tetrodotoxin (TTX)-sensitive sodium channels in cultures of dissociated embryonic chick skeletal muscle cells was examined by measuring the maximum rate of rise of TTX-sensitive spike potential. The addition of the nerve extract prepared from brain or spinal cord of chick embryos to the culture medium caused an increase in the channel density. Extracts of non-neural tissues, i.e., lung, kidney, and muscle, were ineffective Liver extract, however, produced an effect similar to the nerve extracts. These resutls suggest that the TTX-sensitive sodium channels in the muscle cell membrane are regulated by a diffusible chemical substance independently of innervation, and that this substance resides in neural tissues, and perhaps also in liver.
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  • 267
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    Journal of Cellular Physiology 99 (1979), S. 349-357 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Autophosphorylation of 3T3 cells, utilizing endogenous membrane protein kinase, can be detected by incubating the cells with μgM32P-ATP. The phosphorylation activity of growing cells is two to four-fold greater than quiescent ones. In this study, the increased phosphorylation activity of serum-stimulated cells was examined. Phosphorylation, measured at times after serum stimulation of quiescent cultures, was found to increase in early G1 and to reach a maximum prior to DNA synthesis. This increase in stimulated cells was dependent on RNA and protein synthesis but not on DNA synthesis. The increased activity decayed quickly (half-life approximately 2-3 hours) in the presence of cycloheximide, while the basal activity in quiescent cells was relatively unchanged. Insulin, prostaglandin E1 or prostaglandin F2α were also found to bring about the same increase in phosphorylation as serum, although in contrast with serum they caused only a small percentage of the culture to synthesize DNA. The results suggest that enhanced phosphorylation activity is a G1 event. It does not depend on subsequent DNA synthesis. Phosphorylation may be one of the biochemical steps in G1, necessary but not sufficient for cells to move into S phase.
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  • 268
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    Journal of Cellular Physiology 99 (1979), S. 343-348 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Human diploid skin fibroblasts derived from normal individuals and those with the testicular feminization syndrome (TFM) have been shown to be killed to the same degree by dihydrotestosterone in spite of the absence of high affinity cellular androgen receptors in the TFM fibroblasts. Furthermore, several different normal fibroblast strains from various anatomical sites all showed similar amounts of androgen-induced cytotoxicity even though their respective receptor contents differed by as much as ten-fold. These results suggest that steroid-induced cytotoxicity in human fibroblasts in not correlated with receptor content, unlike murine lymphoid cells in which the receptor content has been shown to be closely related to their ability to survive hormone exposure.
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  • 269
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    Journal of Cellular Physiology 99 (1979), S. 333-341 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Glucocorticoids induce several phenotypic changes in rat hepatoma cells in tissue culture, including the inhibition of plasminogen activator activity. Variant cell lines resistant to dexamethasone inhibtion of plasminogen activator activity have been isolated using an agar-fibrin overlay technique to identify colonies with fibrinolytic (plasminogen activator) activity. The variants are resistant to concentrations of dexamethasone 1,000 times that necessary to completely inhibit plasminogen activator activity in wild-type cells. The variant phenotype has been inherited in a stable manner for more than 300 generations in continuous culture in the absence of dexamethasone. These variants are unique in that the resistance is not secondary to defective or absent glucocorticoid receptors but is due to a lesion specific for regulation of plasminogen activator. Fluctuation analyses support the hypothesis that resistance to dexamethasone arises randomly and is not induced by dexamethasone. Because HTC cells are heteroploid and karyotypically highly variable, variants are thought to arise primarily by chromosomal segregation events. These variants provide a valuable tool for studying the mechanism of hormonal regulation of plasminogen activator as well as the role of proteases in hormonal regulation of membrane functions.
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  • 270
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    Journal of Cellular Physiology 99 (1979), S. 359-367 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mitotic HeLa cells (M cells) synthesize protein at about 25% of the rate of S phase cells. This decrease in protein synthesis is due to a reduction in the rate of initiation. However, extracts prepared from M cells are almost as active in protein synthesis as S cell extracts. Both cell extracts are quite active in in vitro initiation of protein synthesis. Moreover, two steps in initiation, binding of Met-tRNAf to 40S ribosomal subunits and binding of mRNA to ribosomes, show similar activity in both extracts. The difference in protein synthesizing activity observed in vivo is largely eliminated in the preparation of cell-free systems. The ribosomes of M cells contain small mot wt RNA, which inhibits protein synthesis in vitro. This RNA, which has possibly a nuclear origin, may be a cause of the reduction in the rate of protein synthesis in M cells.
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  • 271
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    Notes: The growth of cervical carcinoma cell (HeLa) cultures in a hyperosmolar environment stimulates increased production of the onco-developmental peptides human choriogonadotropin (hCG) and follitropin (FSH). This effect was observed in two sublines examined in this study, HeLa65 and HeLa71. hCG and FSH were measured by radioimmunoassay using antiserum against the β-subunit of the hormone dimer, thus insuring immunochemical specificity. The amounts of hCG and FSH produced by HeLa65 and HeLa71 cells cultured in hyperosmolar medium were 2- to 50-fold higher than corresponding hormone levels in basal cultures. Synthesis of gonadotropins depended on concentration and duration of exposure to hyperosmolar medium. Levels of culture medium osmolality effective in inducing hormone production also inhibit the incorporation of 14C-thymidine into acid-insoluble macromolecules. Hyperosmolality thus stimulates the ectopic production of gonadotropic hormones while retarding cellular growth and nucleic acid synthesis.
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  • 272
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    Journal of Cellular Physiology 98 (1979), S. 619-625 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Wild-type Cloudman S91 melanoma cells have a retarded rate of division when agents which raise cyclic AMP levels such as melanotropin, protaglandin E1, or cholera toxin are supplemented to the culture medium. A mutant cell line was isolated which had the opposite response, i.e., the mutant grew very slowly unless agents which raised cyclic AMP levels were present (Pawelek et al., '75a). In this report evidence is presented indicating that the molecular basis for the mutant phenotype resides in the major cyclic AMP-dependent protein kinase found in the cells. The mutant kinase had increased thermolability and an elevated activation constant for cyclic AMP over the corresponding wild-type kinase. It is proposed that the elevated requirement for cyclic AMP for the proliferation of cAdep cells is related to the elevated activation constant of this kinase, suggesting that the kinase is a positive regulator of proliferation in Cloudman S91 cells.
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  • 273
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    Journal of Cellular Physiology 99 (1979) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 274
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    Journal of Cellular Physiology 98 (1979), S. 637-642 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cytoplasts prepared from L929 or Hepa-2 cells were separated from whole cells using density gradients of renografin. Using this technique, cytoplasts can be isolated from cell lines which cannot be routinely enucleated with an efficiency of 100%. The purified cytoplasts excluded the vital dye trypan blue and were utilized in nuclear transplantation experiments to reconstruct whole viable cells capable of division. In addition, the renografin gradient technique was used to separate the newly reconstructed cells from any contaminating “non-renucleated” cytoplasts. This will permit immediate biochemical characterization of cytoplasmic-nuclear hybrid cells without interference from contaminating cytoplasts.
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  • 275
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    Journal of Cellular Physiology 98 (1979), S. 627-635 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The toxicity and extent of growth inhibition produced by chloramphenicol (CAP) in CAPs Chinese hamster cells (line V79-5) was found to be dependent on the type and concentration of hexose in the medium. In high levels of glucose (6.5 mM), cultures of CAPs cells underwent 7-8 population doublings in the presence of 100 μg/ml CAP and viability then dropped rapidly. In contrast, lower concentrations of glucose (1.0 mM) permitted only limited growth (2-3 doublings) in the presence of 100 μg/ml CAP, but the cells remained viable and apparently quiescent for prolonged periods of time. The growth potential of V79-5 cells in CAP appeared specifically dependent on glucose, as mannose and galactose could not substitute for glucose. The toxicity of CAP to these cells seemed to be determined primarily by the number of cell doublings in the presence of the drug.A CAPR derivative of V79-5, designated 5-3, was analyzed in order to determine whether the requirement for glucose for cell growth in the presence of CAP also occurred in cells that were isolated as resistant to the drug. In order to rigorously control the hexose in the medium, some experiments were performed with medium containing dialysed, instead of whole, fetal calf serum. It was seen that the growth of the CAPR line in the presence (but not the absence) of 100 μg/ml CAP was dependent on glucose in the medium. Thus, resistance to CAP in these cells appears to be a conditional state, dependent on glucose for expression. Furthermore, the glucose auxotrophy of these cells in the presence of CAP suggests that CAP is still affecting some activities in cells isolated as CAPR.
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  • 276
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    Notes: Heat-synchronized Tetrahymena pyriformis have been subjected to 5-, 15- and 30-minute pulses of hydrostatic pressure in the range 100-300 atm, without being simultaneously subjected to significant heats of compression. The pressure-induced division delays depend on (1) the level of pressure used, (2) the length of pressure pulse and (3) the time after the synchronizing treatment at which the pressure is applied. A pressure-dependent inhibition of 3H-leucine incorporation into protein was also measured. Comparison of the effects of pressure with those of pulse treatments of cycloheximide and emetine on cell division and protein synthesis revealed that the physical agent produced characteristically different responses from those of the chemical agents. Of particular interest was the fact that the division delays induced by pressures of 200 atm and above were greater than those observed after treatments with cycloheximide and emetine which produced comparable levels of protein synthesis inhibition. Pressure also delayed cells if it was applied at a time when addition of chemical inhibitors had little effect on the first synchronous division. The results show that inhibition of protein synthesis by pressure cannot entirely account for pressure-induced effects on cell division. The possibility that pressure may also directly affect other processes, such as the assembly of proteins into structures required for division, is discussed.
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  • 277
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    Journal of Cellular Physiology 99 (1979), S. 15-22 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A study was made of the transport of a variety of amino acids by uninfected and Rous sarcoma virus-infected chicken embryo fibroblasts. Following a period of amino acid starvation, transformed, but not normal cells, showed increased levels of transport for α-aminoisobutyric acid, proline and alanine, three amino acids which are transported primarily by the A transport system. There was no starvation-induced increase in the transport of leucine, phenylalanine, lysine, or cycloleucine. In the absence of starvation, normal and transformed cells exhibited comparable rates of amino acid transport. Cycloheximide was able to block the increase in uptake. The enhanced uptake was characterized by an increase in Vmax for transport and little change in Km.The data demonstrate that an alteration in the regulation of the A amino acid transport system is an early event in malignant transformation by Rous sarcoma virus. However, since this alteration is made manifest only following a period of starvation, our findings suggest that increased amino acid uptake does not play a role in generating the other manifestations of the transformed state seen in cell culture.
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  • 278
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    Journal of Cellular Physiology 99 (1979), S. 23-30 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: 2-Deoxyglucose transport was characterized in human polymorphonuclear leukocytes (PMN) and rabbit alveolar macrophages (AM). The Km was 1 mM for human PMN and 1.6 mM for rabbit AM, and the Vmax was 0.66 × 10-3 μmoles/45 sec/106 PMN and 5.09 × 10-4 μmoles/45 sec/106 AM. The rate of 2-deoxyglucose transport was the same before and after phagocytosis in PMN from normal individuals and three patients with chronic granulomatous disease, as well as rabbit AM. Studies of the kinetics of 2-deoxyglucose transport and intracellular fate of 2-deoxyglucose in human PMN indicate that the nature of the membrane transport system is not altered by phagocytosis. The results support the concept that the plasma membrane is mosaic in character with geographically separate transport and phagocytic sites.
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  • 279
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    Journal of Cellular Physiology 99 (1979), S. 31-35 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: WCB6F1 mice of the genotype S1/S1d did not form transient 5-day endogenous spleen colonies following midlethal irradiation, either spontaneously or in response to postirradiation bleeding. Their hematologically normal (+/+) littermates produced colonies equivalent in number and morphologic type to a normal strain (D2B6F1), as evaluated by both macroscopic and microscopic criteria. Bone marrow cells from S1/S1d mice, when transplanted into lethally irradiated +/+ mice, were able to generate equivalent numbers of transient endogenous spleen colonies (TE-CFUs), as compared to that obtained when syngeneic +/+ marrow cells were injected into lethally irradiated +/+ recipients. A defective growth of an early class of hematopoietic progenitor cells, resulting in the clinical course of the S1/S1d anemia is suggested and confirms previous reports on the microenvironmental nature of this abnormality.
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  • 280
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: Temporal inhibition of protein synthesis with cycloheximide prevents subsequent insulin, but not serum-stimulated DNA synthesis in G1-arrested chick embryo fibroblasts (CEF). The inhibition is measured by the incorporation of 3H-thymidine into acid insoluble material and confirmed by chemical estimate of the DNA content of inhibited and uninhibited cells. Cycloheximide treatment is without effect if the cell cultures are maintained at 4° C while exposed to the drug. Several α-keto acids (pyruvate, oxaloacetate, α-keto-butyrate) at 0.5-1 mM concentrations restore DNA synthesis in previously inhibited cells when combined with insulin. L-alanine (D-alanine is inert) is even more effective than the keto acids in stimulating DNA synthesis after cycloheximide treatment. Clucose transport was unaffected by cycloheximide treatment while lactate levels in medium from inhibited, insulin-stimulated CEF were reduced 70% compared to uninhibited counterparts. We speculate that cycloheximide treatment may lead to the decay of a glycolytic enzyme which compromises the ability of inhibited cells to synthesize pyruvate from glucose, and thus induces an exogenous requirement for α-keto acid or L-alanine. A serum component(s) with a molecular weight of about 100 permitted insulin-stimulated DNA synthesis in inhibited cells.
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  • 281
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    Journal of Cellular Physiology 101 (1979), S. 399-405 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cultures of heat-synchronized Tetrahymena pyriformis, growing in a proteose peptone medium, were subjected to short pulses of the amino acid analogue, p-flurophenylalanine, and high hydrostatic pressure. The pulses of these agents were chosen so that, when applied individually, they did not appreciably delay cell division. However, combined treatments, analogue pulse followed by pressure pulse, produced a pronounced synergism. The results are interpreted as further evidence to support the inclusion of analogue division proteins in pressure labile assemblies during the progression of Tetrahymena into division.
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  • 282
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    Journal of Cellular Physiology 101 (1979), S. 515-521 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The phenotype of a ouabain-resistant Aedes albopictus cell line has been partially characterized. Treatment of ouabain-sensitive cells with 0.005-1.0 mM ouabain resulted in an 80% reduction in the uptake of 86rubidium (86Rb+), an ion with an affinity for the K+ pump binding site; ouabain-resistant cells showed only a 40% reduction with 1.0 mM ouabain. When ouabain-sensitive cells were incubated in the presence of ouabain (0.1 mM) for one and one-half to three hours, the molar ratio of intracellular Na+/K+ rose from 0.2 to 4.2. In ouabain-resistant cells, a similar treatment had very little effect. Based on [3H] ouabain-binding studies, ouabain-resistant cells were estimated to have 60% fewer binding sites per cell than ouabain-sensitive cells. The spontaneous mutation rate from ouabain sensitivity to ouabain resistance was calculated to be 1-6 X 10-8 mutations/cell/generation, a value similar to that reported for mammalian cells at the analogous locus.
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  • 283
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    Journal of Cellular Physiology 100 (1979), S. 413-424 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Stimulation of Balb/c-3T3 cell growth by TPA requires factors found in serum. We examined the interaction between TPA and serum growth factors in the stimulation of cell growth. The number of cells synthesizing DNA (incorporating 3H-thymidine) within 24 to 30 hours after the addition of TPA and the growth factors to density-inhibited Balb/c-3T3 cultures in serum-free medium was determined by autoradiography. With no additions or with TPA (30-300 ng/ml) alone, only 3-7% of cells synthesized DNA. However, TPA synergistically promoted DNA synthesis in combination with each of the defined serum growth fractions, platelet derived growth factor and platelet poor plasma. TPA also synergistically promoted DNA synthesis in combination with purified growth factors including fibroblast growth factor, insulin (10-6-10-5 M), and epidermal growth factor. In all conditions, TPA enhancement of DNA synthesis also resulted in an increase in cell number. Because TPA synergistically enhanced the activity of each growth factor tested, it did not act identically to any of the growth factors.
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  • 284
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    Notes: Prostaglandin generation by human peripheral blood mononuclear cells is enhanced during co-culture with human thyroid cells. The objective of the present study was to determine the influence of various sera on this process.Human thyroid adenoma cell monolayers were cultured with normal human peripheral blood mononuclear cells for three days in the presence of a variety of sera, or serum fractions. Prostaglandin E (PGE) in the medium was measured by bioassay or by radioimmunoassay. Significantly more PGE was generated in cultures containing fetal calf serum than in those containing human serum. This difference was not abolished by dialysis of the human serum. When the 50% (NH4) 2SO4 precipitate of the serum was used, PGE generation was similar to that in fetal calf serum, indicating the presence of an inhibitory factor in human serum. The degree of this inhibitory activity was similar in autologous and heterologous human serum, as well as in normal subjects and patients with Graves' disease. Gel filtration and ion-exchange chomatography of human serum showed the inhibitor to co-migrate with albumin. Evidence presented suggests that the inhibitor is not albumin itself but is, instead, a factor tightly bound to albumin. Inhibitory activity was also found in rabbit, goat, rat and cow serum.Prostaglandins are potent modulators of immune-cell function. These data indicate that this process may be modulated by a factor in mammalian serum. The relative absence of this factor in fetal serum may have important implications in regard to the profound changes which occur in the immune system after birth.
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  • 285
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    Journal of Cellular Physiology 100 (1979), S. 439-444 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have recently found that aphidicolin, a tetracyclic diterpene-tetraol produced by several fungi, blocks DNA synthesis of sea urchin embryos by interfering with the activity of DNA polymerase α. These cells fail to proliferate in the presence of aphidicolin.In continuation of these studies, we determined the drug-sensitive stage in the first cell cycle of the sea urchin Clypeaster japonicus embryo.In continuous exposure to aphidicolin (2 μg/ml) from five minutes after fertilization, mitotic division of the embryo was completely suppressed. Embryos were exposed to the drug at progressively later intervals and their capability for cytokinesis was examined. Evidence was thereby obtained that aphidicolin acts at the S-period to inhibit DNA synthesis resulting in developmental arrest of the embryo.
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    Journal of Cellular Physiology 100 (1979), S. 445-455 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Treatment of embryonic chick heart fibroblast cultures with 0.2 M urea reversibly increases cellular overlap. The increase in cellular overlapping over that in control cultures may be quantitated by the overlap ratio (R), the ratio of the number of superimposed nuclei observed, to the number expected to occur when cells are assumed to be distributed randomly over the culture substratum (R = observed/expected overlaps). Reversal of the urea-induced increase in R is blocked by 0.2 μg/ml cycloheximide. In the presence of cycloheximide, normal (low) overlap ratios are restored to urea-treated cultures by adding non-dialyzable material recovered by washing fibroblast monolayers with serum-free medium. The overlap ratio assay revealed no effect of supernatant material added either to urea-treated cultures in the continued presence of urea, or to untreated cultures. Although unfiltered supernatants were shown by SDS-polyacrylamide gel electrophoresis to contain fibronectin (CSP; LETS; MWappar. = 220,000 d) and smaller proteins, the ability to reverse the urea-induced increase in overlap ratio was present in Diaflo and Millipore filtrates of culture supernatants in which fibronectin was greatly depleted or absent. In contrast, purified fibronectin preparations failed to lower urea-induced increases in overlap-ratio. Partially purified, biologically active supernatants, prepared from 14C-leucine or 125I-labeled cultures, contained several macromolecules smaller than fibronectin that were labeled by both radioisotopes. In particular, one band (MWappar. = 58-60,000 d) was present in polyacrylamide gels of active supernatant and also depleted in gels of homogenates from urea-treated cultures. These results indicate that external macromolecules other than fibronectin are synthesized by culture fibroblasts and can affect cell social behavior or culture morphology.
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    Journal of Cellular Physiology 100 (1979), S. 467-479 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The addition of a chemical inducer, such as dimethylsulfoxide (DMSO), to cultures of mouse Friend erythroleukemic cells results in the induction of a number of late erythroid events, including the accumulation of globin mRNA, the induction of hemoglobin synthesis, the appearance of erythrocyte membrane antigens (EMA), and the cessation of cell division. The experiments presented in this study demonstrate that heme is necessary but not sufficient for the loss of proliferative capacity associated with DMSO-induced Friend cell differentiation, whereas the accumulation of globin mRNA and EMA can occur in the absence of heme synthesis or heme itself. These conclusions were reached by selectively inhibiting heme synthesis in DMSO-treated cells in two independent ways: (i) Inducible cells were treated with 3-amino-1,2,4-triazole (AT), a drug which inhibits the induction of heme synthesis in Friend cells in a dose-dependent manner. Treatment of inducible Friend cells with 1.5% DMSO for five days caused the plating efficiency in methyl cellulose to decrease to 1% of that in untreated cultures. However, treatment of the cells with DMSO plus AT almost totally prevented this decrease in plating efficiency. The addition of exogenous hemin, which alone had no significant effect on plating efficiency, largely reversed the effect of AT in DMSO-treated cells, reducing the plating efficiency to below 5%. In contrast to the marked effects of AT on the proliferative capacity of differentiating Friend cells, the levels of globin mRNA and EMA were only partially decreased in cells treated with DMSO plus AT, compared to cells treated with DMSO alone. (ii) The relationship between heme synthesis, terminal cell division, and the induction of globin mRNA was investigated further through the use of non-inducible Friend cell variant clones. One such non-inducible clone, M18, appears to be a phenotypic analog of inducible cells treated with DMSO plus AT. Clone M18 did not accumulate heme or hemoglobin, as detected by benzidine staining, nor lose its proliferative capacity in response to DMSO. However, globin mRNA was induced by DMSO in this clone. Treatment of clone M18 with DMSO plus hemin overcame the block in hemoglobin accumulation suggesting that M18 has a defect in the induction of heme biosynthesis. In addition, exposure of M18 cells to DMSO plus hemin caused a gradual decrease in plating efficiency which was not due to non-specific toxicity. Prior incubation of M18 cells in DMSO for three to five days was necessary before hemin caused a rapid loss of proliferative capacity. Thus, these results, in agreement with the AT studies on inducible Friend cells and previous studies on the induction of EMA in clone M18, indicate that there may be both heme-dependent and heme-independent events in the program of Friend cell differentiation.
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  • 288
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have examined the distribution of several mechanochemical proteins inside rat A10 cells in monolayer culture, both in sparse cultures and at the edges of in vitro “wounds” in confluent cultures. The proteins examined were actin, myosin, tropomyosin, α-actinin, filamin, and tubulin. In each experiment, a pair of these proteins (one of which was usually actin) were examined simultaneously by double fluorescence staining methods. Actin was specifically stained by a method based on heavy meromyosin binding, whille the other proteins were specifically stained by indirect immunofluorescence procedures. The most important of the various results described was obtained with cells moving out from the edge of an in vitro wound. Within the flat leading lamella of such a cell, there was an extended region in which myosin was severely depleted or absent compared to the proximal regions of the same cells. By contrast, the other proteins were abundantly present throughout the leading lamella, except for tropomyosin, which was somewhat depleted but not as extensively as myosin. In Nomarski optics, there was no detectable morphological differentiation between the region depleted of myosin and the more proximal portion of the same lamella. While the depletion of myosin from the motile regions of cells does not rule out the involvement of some form of an actomyosin sliding filament mechanism, it suggests that other molecular mechanisms for generating motility be seriously considered.
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  • 289
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    Journal of Cellular Physiology 100 (1979), S. 551-561 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cation loss and hemolysis of various mammalian red cells suspended in isotonic non-electrolyte media were investigated. Sucrose buffered with 10 mM Tris-Hepes, pH 7.4 was used as the non-permeable non-electrolyte. Mammals from which the red cells were derived include the human, guinea pig, rat, rabbit, newborn calf, newborn piglet and pig, all of which contain K as the predominant cation species (HK type) and the dog, cat, sheep and cow, all of which possess Na as the predominant cation species (LK type). Of HK cells, a rapid efflux of K takes place from humans, rats and guinea pigs. Of LK type cells, the dog and cat exhibit an augmented membrane permeability to Na. The governing factors which influence cation permeability are the change in pH, temperature, and ionic strength. In response to increase in pH, the red cells of humans, dogs and cats become more permeable to cations, whereas the red cells of rat and rabbit are unaffected. In response to increase in temperature, HK type cells exhibit augmented K efflux, while the Na loss from the dog and cat cells manifest a well-defined maximum at near 37°C. In all cases, a small substitution of sucrose by an equal number of osmoles of salts results in a dramatic decrease in cation loss. By contrast, the red cells of the rabbit, newborn calf, adult cow, newborn piglet, adult pig and sheep display no discernible increase in ion-permeability under the conditions alluded to above. In some species including the newborn calf, dog and cat, an extensive hemolysis occurs usually within an hour in isotonic buffered sucrose solution. The osmolarity of sucrose solution affects these cells differently in that as the osmolarity increases from 200-500 mM, hemolytic rates of the calf and dog reach a saturation near 300 mM sucrose, whereas the hemolytic rate of the cat decreases progressively. Common features pertaining to this hemolysis are (1) the intracellular alkalinization process; and (2) the diminution of the cell volume which take place prior to and onset of hemolysis. SITS, a potent anion transport inhibitor, completely protects the cells from hemolysis by inhibiting chloride flux and the concomitant rise in intracellular pH.
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  • 290
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    Journal of Morphology 159 (1979), S. 29-47 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Early spermatids of the onychophoran Peripatopsis capensis are spherical cells with a centrally located nucleus, numerous mitochondria, Golgi complexes, microtubules and two centrioles. During spermiogenesis, Golgi vesicles migrate to one side of the cell where they form a tight aggregate, which is later shed. The mature spermatozoon has no acrosome. Several mitochondria fuse to form a middle piece containing three large mitochondria. Nucleus and middle-piece elongate, presumably under the influence of helically twisted microtubules. Outside this set of microtubules a continuous layer of endoplasmic reticulum cisternae is formed which separates the interior portion of the cell from an external cytoplasmic rim, which is later shed. Outside the 9 + 2 complex, the tail presents nine accessory microtubules, and a peripheral layer of microtubules beneath the plasma membrane. The enforcement of the tail structure may be related to the fertilization biology of this animal, which is by “hypodermal” impregnation.
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  • 291
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    Journal of Morphology 159 (1979) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 292
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The three major salivary glands of the monotreme echidna are described. The parotid is a typical serous gland with tubulo-acinar secretory endpieces and a well-developed system of striated ducts. The mandibular gland, although light microscopically resembling a mucous gland, secretes very little glycoprotein. Its cells are packed instead with serous granules, resembling in fine structure the “bull's eye” granules in the mandibular gland of the European hedgehog Erinaceus europaeus. The sublingual glands secrete an extremely viscous mucous saliva. Expulsion of this saliva through the narrow ducts is probably aided by contraction of the extensive myoepithelial sheaths surrounding the secretory tubules. Application of the glyoxylic acid induced fluorescence method failed to demonstrate adrenergic innervation in any of the glands.
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  • 293
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    Journal of Morphology 160 (1979), S. 103-119 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Classical light microscopic studies on pigmentation of Fundulus heteroclitus (killifish) indicated that there are three groups of light reflecting cells; one group on the surface of scales reflects white light, while two other deeper groups (the melaniridophores and the stratum argenteum) are iridescent. The results presented here show that: (1) The scale leucophores reflect white light by a Tyndall light-scattering mechanism, by virtue of the presence of randomly oriented organelles of “novel” morphology. (2) The iridophores of the melaniridophores contain stacks of irregularly-spaced, large reflecting platelets which function as an imperfect multiple thin layer interference system. (3) The stratum argenteum consists of a continuous layer(s) of iridophores with reflecting platelets which are so regularly packed as to approach an ideal multiple thin layer interference system. (4) In all three types of light reflecting cells, the dimensions and packing (orientation) of the reflecting organelles satisfactorily account for the chromogenic properties of the cells, including colors as viewed under transmitted, reflected, or polarized light. (5) The spacial relationships between these light reflecting cells and adjoining melanophores are different for each type of light reflecting cell. Furthermore, we propose to replace the term reflecting platelet with refractosome.
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  • 294
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    Journal of Morphology 160 (1979), S. 143-163 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The chloride cells in the interlamellar areas of the gills of young adult, anadromous sea lampreys, Petromyzon marinus L., captured in fresh water undergo structural modification during the adaptation of these animals to sea water. In fresh water the chloride cells are partially overlapped by mucus-secreting superficial cells and contain an extensive reticulum of cytoplasmic tubules, which are confluent with both lateral and basal plasma membranes, numerous mitochondria, a Golgi complex of moderate size, and numerous apical vesicles. Adaptation to sea water results in a retraction of the superficial cells, exposing the entire apical surface of the chloride cells, and a proliferation of both cytoplasmic tubules and mitochondria. Extensive enlargement of the Golgi complex in the chloride cells of these animals suggests the involvement of this organelle in the proliferation of cytoplasmic tubules. The extracellular tracer, ruthenium red, enters the tubules from the lateral or basal intercellular spaces in both freshwater- and seawater-adapted animals but never enters either tubules or vesicles from the apical surfaces, indicating that these are not confluent. The presence of dividing basal cells and newly-forming chloride cells, combined with evidence of degeneration of chloride cells, suggests that there is a turnover of this cell type. Both superficial and basal cells are phagocytic and involved in heterophagy of degenerating chloride cells. This phenomenon occurs in both fresh water and sea water indicating that the chloride cells may be functional in both environments.
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  • 295
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    Journal of Morphology 160 (1979) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 296
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    Journal of Morphology 159 (1979), S. 233-243 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Patterns of tracheation in the abdominal central nervous system and the cerci of Acheta domesticus are described from whole mounts, and light and electron microscopy.The tracheal supply of the ganglia is derived from ventral longitudinal tracheal trunks which have segmental connections to the spiracels. Each abdominal ganglion is served by a single pair of tracheal trunks, except the terminal ganglion, which has two pairs. Within the ganglia, tracheoles occur principally in association with glia-rich areas of the neuropile. We suggest that the respiratory exchange may be concentrated in the cell bodies of neurons and glia. Each cercus has a tracheal supply in paralle with a large air sac which, it is suggested, serves to lighten the cercus, functions as a resonator for sound reception, or facilitates tidal flow of hemolymph and postecdysial expansion of the cercus. No tracheae run continuously between ganglia or between the terminal ganglion and the cerci, and they do not appear to have a potential role as a contact guidance pathway for cercal nerve growth.
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  • 297
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    Journal of Morphology 159 (1979), S. 311-329 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Normal development of the urostyle is described during late stages of metamorphosis in five species of anurans: Xenopus laevis (Daudin), Bufo americanus Holbrook, Pseudacris triseriata (Wied), Hyla chrysoscelis Cope, and Rana pipiens Schreber. The developing urostyle of all five species is composed of essentially the same cartilaginous elements: one pair of basidorsals above the notochord and the subtended hypochord. Among the five species there is variation in such details as the number of spinal nerve foramina and the degree of fusion of the basidorsals; however, both the hypochord and basidorsals are very similar in all five genera examined. Consideration of the literature suggests that contradictory descriptions of the developing urostyle result from (1) varied methods of study (alizarin-staining of whole specimens or serial cross-sections), (2) the variety of species examined, and (3) the particular stage of development of the tadpole described by an investigator.
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  • 298
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    Journal of Morphology 159 (1979), S. 393-425 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Branchial food traps are regions of specialized secretory tissue in the tadpole pharynx, where suspended food particles are trapped in mucus.Light and scanning electron microscopy were used to study branchial food traps from larvae of ten anuran families (36 species). Most anuran larvae from “advanced” (suborder Neobatrachia) families (e.g., Hylidae, Ranidae, Bufonidae) have distinct secretory pits at the posterior margins of the branchial food traps and secretory ridges elsewhere on these surfaces. The apices of columnar PAS-positive, secretory cells are exposed on the floors of the secretory pits or in rows at the tops of the secretory ridges (secretory zone).Tadpoles from most “archaic” (suborder Archaeobatrachia) families (Ascaphidae, Discoglossidae and Pelobatidae) either lack secretory pits, or have them poorly defined. They also lack secretory ridges but have columnar, mucus-secreting cells whose apices are exposed in a seemingly random fashion in the branchial food traps. Rhinophrynus (Archaeobatrachia: Rhinophrynidae) has secretory ridges, but the apices of secretory cells are not arranged in rows at the tops of the ridges; instead they erupt singly or in small clusters on the epithelial surface, in a pattern similar to that in Ascaphus, the discoglossids and the pelobatids. It is proposed that the generalized condition for the branchial food trap mucosa is one where the apices of secretory cells are exposed haphazardly on a flat epithelium and the derived condition is one where the surface is organized into ridges. The morphology of the branchial food traps in Rhinophrynus suggests that, phylogenetically, ridges preceded the coalescing of secretory cell apices into distinct rows.Pipidae and Microhylidae have unique patterns in the gross and microanatomy of their branchial food traps specific to their families.Branchial food trap morphology relates to diets of tadpoles as well as to taxonomy. Obligate macrophagous (e.g., carnivorous) tadpoles, irrespective of family, tend to have reduced branchial food traps, regularly lack secretory ridges and, in extreme cases, lack columnar mucus-secreting cells. Obligate microphagous forms (midwater suspension feeding of Xenopus, microhylids and Agalychnis), have straight parallel secretory ridges with narrow secretory zones and shallow troughs between the ridges.Secretory ridges may help to form mucus strands in which food particles are trapped, but they are not essential for planktonic entrapment. The hydrodynamic implications of the various topographic patterns remain unclear.
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  • 299
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    Journal of Morphology 160 (1979), S. 1-5 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Tactile hairs, small chemoreceptor pegs, thick-walled chemoreceptors, thin-walled chemoreceptors of several types, coeloconic sense organs and campaniform sense organs are present on the flagellum of a stonefly, Allocapnia recta (Claassen).
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  • 300
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A stress analysis of the primate mandible suggests that vertically deep jaws in the molar region are usually an adaptation to counter increased sagittal bending stress about the balancing-side mandibular corpus during unilateral mastication. This increased bending stress about the balancing side is caused by an increase in the amount of balancing-side muscle force. Furthermore, this increased muscle force will also cause an increase in dorsoventral shear stress along the mandibular symphysis. Since increased symphyseal stress can be countered by symphyseal fusion and as increased bending stress can be countered by a deeper jaw, deep jaws and symphyseal fusion are often part of the same functional pattern. In some primates (e.g., Cercocebus albigena), deep jaws are an adaptation to counter bending in the sagittal plane during powerful incisor biting, rather than during unilateral mastication.The stress analysis of the primate mandible also suggests that jaws which are transversely thick in the molar region are an adaptation to counter increased torsion about the long axis of the working-side mandibular corpus during unilateral mastication. Increased torsion of the mandibular corpus can be caused by an increase in masticatory muscle force, an increase in the transverse component of the postcanine bite force and/or an increase in premolar use during mastication.Patterns of masticatory muscle force were estimated for galagos and macaques, demonstrating that the ratio of working-side muscle force to balancing-side muscle force is approximately 1.5:1 in macaques and 3.5:1 in galagos during unilateral isometric molar biting. These data support the hypothesis that mandibular symphyseal fusion is an adaptative response to maximize unilateral molar bite force by utilizing a greater percentage of balancing-side muscle force.
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