摘要:

AbstractHeat‐synchronizedTetrahymena pyriformishave 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 of3H‐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 divis

ISSN:0021-9541    

DOI:10.1002/jcp.1040990102

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

年代:1979

数据来源: WILEY

摘要:

AbstractA 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 Vmaxfor 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 c

ISSN:0021-9541    

DOI:10.1002/jcp.1040990103

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

年代:1979

数据来源: WILEY

摘要:

Abstract2‐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 × 10−3μmoles/45 sec/106PMN and 5.09 × 10−4μmoles/45 sec/106AM. 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 p

ISSN:0021-9541    

DOI:10.1002/jcp.1040990104

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

年代:1979

数据来源: WILEY

摘要:

AbstractWCB6F1mice of the genotype S1/S1ddid 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/S1dmice, 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/S1danemia is suggested and confirms previous reports on the microenvironmental nature of this abnormal

ISSN:0021-9541    

DOI:10.1002/jcp.1040990105

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

年代:1979

数据来源: WILEY

摘要:

AbstractTunicamycin, 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 metabol

ISSN:0021-9541    

DOI:10.1002/jcp.1040990106

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

年代:1979

数据来源: WILEY

摘要:

AbstractT98 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 aspe

ISSN:0021-9541    

DOI:10.1002/jcp.1040990107

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

年代:1979

数据来源: WILEY

摘要:

AbstractPuromycin 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 matura

ISSN:0021-9541    

DOI:10.1002/jcp.1040990108

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

年代:1979

数据来源: WILEY

摘要:

AbstractWe 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 ag

ISSN:0021-9541    

DOI:10.1002/jcp.1040990109

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

年代:1979

数据来源: WILEY

摘要:

AbstractTransmembrane 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) and14C‐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 diff

ISSN:0021-9541    

DOI:10.1002/jcp.1040990110

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

年代:1979

数据来源: WILEY

摘要:

AbstractA separation procedure has been developed for mouse splenic T and B lymphocytes which is based on their differential agglutination by wheat germ agglutinin (WGA). In the presence of 50‐100 μg/ml of WGA, multicellular aggregates are formed which are enriched in B cells. These aggregates can be separated from monodisperse T cells by gravity sedimentation and subsequently dissociated into single cells by treatment with N‐acetylglucosamine (NAG). Immunocytochemical analyses and mitogenic assays indicate approximately 10‐15% cross contamination of the resultant B and T cell fractions. The separation procedure is not only convenient and rapid but also allows the simultaneous recovery of viable T and B cells from the same spleen prepa

ISSN:0021-9541    

DOI:10.1002/jcp.1040990111

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

年代:1979

数据来源: WILEY