摘要:

AbstractPreincubation of C57BL adult marrow cells or CBA fetal liver cells with a 250‐fold excess concentration of purified GM‐CSF failed to reduce the frequency of cells forming eosinophil, megakaryocyte or erythroid colonies in subsequent agar cultures. When excess concentrations of purified GM‐CSF were added to agar cultures stimulated by pokeweed mitogen‐stimulated spleen conditioned medium (SCM), no reduction was observed in the frequency of eosinophil, megakaryocyte or erythroid colonies. Addition of 4 units of purified erythropoietin (EPO) to cultures of fetal liver or adult marrow cells stimulated by SCM increased the number of erythroid colonies but did not reduce the number of non‐erythroid colonies or the non‐erythroid content of mixed erythroid colonies.Although neither GM‐CSF nor EPO alone was able to stimulate erythroid colony formation in agar cultures of fetal liver cells, small numbers of large erythroid colonies were stimulated to develop in cultures containing both purified regulators. Purified GM‐CSF was also able to support the survival in vitro of a small proportion of erythroid colony‐forming cells in fetal liver populations cultured initially in the absence of SCM and the survival of some eosinophil and megakaryocyte colony‐forming cells in similar cultures of adult marrow cells.The results do not support the hypothesis that GM‐CSF and EPO compete for a common pool of uncommitted progenitor cells. On the contrary, the data indicate that GM‐CSF and EPO are able to collaborate in stimulating the proliferation of some erythropoietic cells. Furthermore, purified GM‐CSF appears to be able to support temporarily the survival and/or initial proliferation of at least some cells forming erythroid, eosinophil and megakaryocyte colonies, even though GM‐CSF is unable to stimulate the formation

ISSN:0021-9541    

DOI:10.1002/jcp.1040990202

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

年代:1979

数据来源: WILEY

摘要:

AbstractFollicle stimulating hormone (FSH) stimulates “colony formation” by immature rat Sertoli cells in primary culture. “Colony formation” involves cell aggregation. Consequently, the involvement of cell surface glycoproteins in cell aggregation was investigated by treatment of dissociated 10‐day rat testis cells with sodium metaperiodate, glucosamine, various lectins, tunicamycin, and puromycin. Treatment of control cultures with 5 μM glucosamine stimulated cell aggregation; however, glucosamine did not affect FSH‐stimulated cultures. Treatment of dissociated testis cells with 5 μM sodium metaperiodate, 10 μg/ml castor bean agglutinin (ricin), or 2.5 μg/ml horseshoe crab agglutinin inhibited FSH stimulation of cell aggregation. A similar inhibition of cell aggregation was observed following addition of 10 μg/ml puromycin or tunicamycin to culture media from 0‐ to 18‐hours incubation. Treatment with soybean agglutinin, concanavalin A, or wheat germ agglutinin had no effect. The galactose‐specific lectins, Ricin,Ricinus communisagglutinin I, andBendeirea simplicifoliaagglutinin, inhibit the FSH stimulation of3H‐aminoacid incorporation as well as cell aggregation in 24‐hour cultres. The inhibition of cell aggregation by sodium metaperiodate treatment was reversed with 5 μM sodium borohydride reduction. Sodium metaperiodate treatment did not alter cell viability (as assayed with trypan blue dye exclusion), did not alter cell attachment, nor significantly decrease125I‐FSH binding by cultured testis cells. The results suggest that FSH stimulation of cell aggregation by immature rat Sertoli cells requires cell surface glycoprotein interactions. Furthermore, the specificity of lectin inhibition suggests that glycoproteins with terminal galactose and sialic acid residues are required for the FSH

ISSN:0021-9541    

DOI:10.1002/jcp.1040990203

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

年代:1979

数据来源: WILEY

摘要:

AbstractExogenous 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 HMOAcells, a recently cloned rat hepatoma cell line that has a greatly stabilized ODC, it has been possible to demonstrate that 10−5M 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 10−2M 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 thi

ISSN:0021-9541    

DOI:10.1002/jcp.1040990204

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

年代:1979

数据来源: WILEY

摘要:

AbstractVero (African green monkey kidney) cells grown in tissue culture monolayer were sensitive toClostridium perfringensenterotoxin. Within 30 minutes of exposure to the enterotoxin gross morphological damage was observed and within 40 minutes approximately 75% of the cells had detached. Nearly half of the cells were nonviable following 35 to 40 minutes incubation with the enterotoxin. Doses as low as 0.1 ng caused small but detectable inhibition of plating efficiency of the cells while more than 100 ng caused the inhibition to approach 100%. Total inhibition of DNA, RNA, and protein synthesis occurred within 30 minutes exposure to enterotoxin. Heat inactivated enterotoxin had no apparent effects upon cellular morphology, detachment, viability, plating efficiency, or incorporation. We propose that the enterotoxin induces structural damage to the cytoplasmic membrane which results in loss of electrolytes and other essential substances from the cells. The outcome of this process is shut down of macromolecular synthesis, gross morphological damage, and eventual death of the cell.

ISSN:0021-9541    

DOI:10.1002/jcp.1040990205

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

年代:1979

数据来源: WILEY

摘要:

AbstractThe sulfated mucopolysaccharide composition of normal and virus transformed Balb 3T3 and BHK21cell lines is reported. It is shown that normal 3T3 cells contain mainly chondroitin sulfate B and heparitin sulfate. Relatively higher amounts of chondroitin sulface AC were observed in polyoma virus transformed 3T3 cells, besides an absolute increase of all the three sulfated mucopolysaccharides in the polyoma and SV 40 transformed cells. It is shown also that the three sulfated mucopolysaccharides are at least in part at the cell surface. Similar differences in sulfated mucopolysaccharide composition of normal and virus transformed BHK cell lines were also observed.

ISSN:0021-9541    

DOI:10.1002/jcp.1040990206

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

年代:1979

数据来源: WILEY

摘要:

AbstractThe onset and rate of semiconservative DNA replication were measured in stimulated cultured rat fibroblasts and their Rous sarcoma virus‐transformed derivatives after a period of serum deprivation. Rat‐1 (tsLA24/RSV) cells initiated DNA synthesis following a shift to the permissive temperature or addition of serum at the non‐permissive temperature. Their rate of DNA replication was unaffected by the presence of serum at the permissive temperature, however, there was a serum requirement at the non‐permissive temperature. The transition probability was less at the permissive temperature, independent of serum, than at the non‐permissive temperature in the presence of serum. The amount of DNA induced to replicate by addition of serum at the non‐permissive temperature or by a shift to the permissive temperature was similar. Using the untransformed Rat‐1 cells and these cells transformed by wild‐type RSV (Rat‐1 (wt/RSV)), it was confirmed that the rate of entry into S phase (transition probability) was always lower in the transformed cell line at both 39° and 35°. In both cell lines the rate of DNA replication was independent of temperature, but the onset was delayed at the lower temperature. These results indicate that in the cell lines examined, (1) serum was able to commit the cells to replicate DNA (alter the transition probability) in both transformed and untransformed cells, but the transforming function was able to supplant a serum‐dependent process during G1necessary for the initiation of DNA replication, and (2) the effects of the transforming function and serum factor(s) on the alteration of the transition probability are not additive, suggesting that the transforming function initiates a process which acts at the level of the commitment to DNA replication which may render the normal serum‐related control mechanisms ineffective in t

ISSN:0021-9541    

DOI:10.1002/jcp.1040990207

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

年代:1979

数据来源: WILEY

摘要:

AbstractWe are examining the relationship of RNA metabolism and de novo pyrimidine synthesis as parameters of malignant transformation. These initial experiments on normal hamster embryo fibroblasts have shown that excreted nucleosides are markers for intracellular RNA metabolism. We employed affinity chromatography to concentrate the nucleosides in the medium and sensitive column chromatographic procedures to quantitatively measure them. The excretion of pyrimidine nucleoside from hamster embryo fibroblasts in culture was found to be dependent on the growth stage of the cells, with the greatest accumulation occurring during cell quiescence. The major nucleoside excretion products, uridine and cytidine, were both normal end products of RNA metabolism and the major nucleoside excretion products from cultured cells. The modified nucleosides N‐1‐methylguanosine, N‐2‐methylguanosine, N‐2‐dimethylguanosine, N‐4‐acetylcytidine, N‐1‐methylinosine, pseudouridine, N‐1‐methyladenosine, N‐3‐methylcytidine, and 5‐methylcytidine were found, as were sev

ISSN:0021-9541    

DOI:10.1002/jcp.1040990208

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

年代:1979

数据来源: WILEY

摘要:

AbstractThe morphological aspects of spermatogenesis are well described in many mammalian species, but functional changes are not completely understood. Electrophysiological parameters were investigated in primary spermatocytes and early and late spermatids isolated from the seminiferous tubules of the mouse. Substantial changes were not detected in membrane potential between different developmental stages. Membrane potential was dependent on both potassium and sodium ion concentration gradients, but not on chloride gradients. The ratio of the permeabilities PNa/PKvaried according to the extracellular concentrations of sodium and potassium. Ouabain, a specific inhibitor of Na+, K+‐activated ATPase, produced a maximal reduction in membrane potential of 20% Comparisons were drawn between differentiating germ cells and previously determined properties of mature spermatozo

ISSN:0021-9541    

DOI:10.1002/jcp.1040990209

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

年代:1979

数据来源: WILEY

摘要:

AbstractThe ability of human serum to support erythroid an dgranulocytic colony formation has been investigated. It was found that normal human serum could replace fetal calf serum in the cultures and was able to support the growth of these hemopoietic colonies. Serum fractions enriched for low density lipoproteins, either by precipitation with Heparin‐Mn++or by ultra‐centrifugation, was found to contain this growth supporting activity of human se

ISSN:0021-9541    

DOI:10.1002/jcp.1040990210

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

年代:1979

数据来源: WILEY

摘要:

AbstractA 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 v

ISSN:0021-9541    

DOI:10.1002/jcp.1040990211

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

年代:1979

数据来源: WILEY