bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phosphate transport in fertilized sea urchin eggs. II. Effects of metabolic inhibitors and studies on differentiation
Authors: Whiteley Arthur H. , Chambers Edward L. 
Published: February 2005

AbstractMetabolic inhibitors were applied after the transport system was fully developed in concentrations sufficient to block cleavage. 0.5–1.0 × 10−4 M cyanide and anaerobiosis caused from negligible to moderate (40%) inhibition of phosphate uptake. The inhibition occurred late in the breeding season, and the inhibitory action of cyanide on uptake was associated with irreversible developmental effects. Azide (3 × 10−3 M) did not inhibit uptake when the chamber method was used, but the aliquot and Hopkins' tube methods gave considerable inhibition. Purified preparations of 2,4‐dinitrophenol (1 × 10−4 M) did not inhibit uptake. Sodium iodoacetate (up to 0.05 M) and phlorizin (0.005 M) exerted no effect.Calculations of the minimal work requirement for the transport process reveal that this amounts to only a small fraction (0.24% at an external phosphate concentration of 2 μM) of the total available metabolic energy.Exposure of eggs at five minutes after insemination (lag phase) to cyanide (5 × 10−5 M), anaerobic conditions, or azide (3 × 10−3 M) blocked the expected increase of phosphate uptake. Removal of the inhibitors led to resumption of development and the appearance of the phosphate transport system in an essentially normal pattern.Exposure of eggs to 1.4–2.0 × 10−4 M p‐chloromercuribenzoate (p‐CMB) during the accumulation phase severely depressed phosphate uptake, but cleavage was not inhibited nor delayed; recovery from the inhibition was accelerated by 1 × 10−3 M cysteine. Exposure to p‐CMB during the lag phase blocked the appearance of the transport system; cleavage proceeded normally. After the removal of p‐CMB little reversal occurred until the addtion of 1 × 10−3 M cysteine, when the phosphate transport system developed in an essentially normal manner.Trypsin (0.001–0.01%) neither activates the transport system in unfertilized eggs, nor inactivates it in denuded fertilized eggs by removal of surface proteins.The data are consistent with the conclusion that (1) the phosphate transport system is newly synthesized at fertilization in energy dependent reactions, and (2) phosphate transport is a carrier mediated process not directly dependent on metabolic energy.
The Mg, Ca, EDTA and ATP dependence of Na binding by rat liver microsomes
Authors: Sanui Hisashi , Pace Nello 
Published: February 2005

AbstractThe role of ionic interactions in the adenosinetriphosphate (ATP) dependent Na binding by rat liver microsomes was investigated. In the concentration range of 0 to 20 mM, Mg and Ca are demonstrated to compete strongly against Na for microsome binding sites. In the presence of Ca, the nonbiological complexing agent ethylenediaminetetraacetate (EDTA) produced a marked increase in Na binding accompanied by a concomitant decrease in Ca binding. Under similar conditions ATP, which is a weaker complexing agent than EDTA, produced quantitatively smaller but qualitatively similar changes in binding. The data show that the effect of ATP on Na binding is not dependent upon the formation of a hypothetical Na binding intermediate in the hydrolysis of ATP as other investigators have postulated. Rather, the effect of ATP is demonstrated to depend upon the presence of unhydrolyzed ATP and its ability to complex divalent cations, and thereby to reduce divalent cation competition against monovalent cations for membrane binding sites.
Nucleolar RNA synthetic activity in chinese hamster cells in vitro and the effects of actinomycin D and nogalamycin
Authors: Arrighi Frances E. 
Published: February 2005

AbstractRNA synthesis was studied by autoradiographic analysis using tritiated uridine incorporation in the Chinese hamster cell line Dede after a one‐minute pulse labeling period. RNA synthesis continues during all stages of interphase and mitosis except during metaphase and anaphase. Cytoplasmic RNA was apparently synthesized in the nucleus, since no grains were observed above the background level in the sample immediately following the labeling. Nucleoli synthesize their own RNA and are not reservoirs for RNA synthesized elsewhere. Both actinomycin D and nogalamycin inhibited the RNA synthetic activity of chromatin and nucleoli. However, the nucleolar synthetic activity was more susceptible to these agents than that of chromatin. Furthermore, actinomycin D was a stronger inhibitor than nogalamycin.
Some properties of alkaline phosphatase from a human cell strain and from a clonal derivative with low activity
Authors: Santachiara‐Benerecetti Silvana A. , Cesari I. , De Carli L. 
Published: February 2005

AbstractA comparative study of some physico‐chemical properties of alkaline phosphatase of a human cell line, the EUE, with high level of enzyme and one of its clonal derivatives the E6D, with low activity, has been carried out.Electrophoretic analysis reveals a multiple banding pattern within each line and qualitative differences between the two lines. The alkaline phosphatase activity of the E6D cell extracts is almost completely inhibited by 5 × 10−2 M inorganic phosphate while in the EUE the enzymic activity is reduced to one third under these conditions. The enzymes of the two lines show also a different thermostability which is not referable to extrinsic factors, as demonstrated by mixing experiments. The time course of heat inactivation at 70°C suggests molecular heterogeneity in each line, and a prevalence of a thermostable fraction in the cells with low activity and a thermolabile one in those with high enzymic levels. A rough estimate of inactivation constants does not rule out the possibility that the molecular species in the two lines are the same but in different proportions. The cytological analysis confirms the relationship between the number of small acrocentric chromosomes and alkaline phosphatase levels. The significance of the biochemical data in relation to the proposed model of a gene dosage effect is discussed.
An effect of exogenous thymidine on the cell cycle in Haplopappus gracilis
Authors: Ames Ira H. , Mitra Jyotirmay 
Published: February 2005

AbstractThe study of an effect of exogenous thymidine on the mitotic cycle demonstrated that a 30 minute exposure to unlabeled and to tritiated thymidine at a concentration of 2.9 × 10−6 M was sufficient to cause a significant increase in the mitotic index of root meristem cells of Haplopappus gracilis. An analysis of the data revealed that this was due to the prolongation of metaphase rather than to an increase in the actual number of cells entering division.
K+‐stimulated phosphatase of microsomes from gastric mucosa
Authors: Forte John G. , Forte Gertrude M. , Saltman Paul 
Published: February 2005

AbstractThe light microsomal fraction was isolated from homogenates of rabbit and bullfrog gastric mucosa. On examination with the electron microscope, the light microsomes appear as tubular membranous structures with morphology and dimensions similar to the elements of the smooth‐surfaced endoplasmic reticulum seen in intact oxyntic cells. A K+‐stimulated, Mg++‐requiring p‐nitrophenylphosphatase has been demonstrated in the gastric microsomes. Neither Na+ nor ouabain (10−6–10−3 M) altered the K+‐stimulated phosphatase. SCN− was not very effective as an inhibitor of the gastric microsomal phosphatase, in contrast to the effect of this anion on the ATPase activity; however, the gastric phosphatase as well as the ATPase are destroyed by phospholipase C, thus showing the lipoprotein nature of these enzymes. Kinetics of the K+ activation of the microsomal phosphatase suggest that the K+‐PNPP complex is the active substrate for the enzymic reaction. Rb+, NH4 + and Cs+ will substitute to some degree for K+ as an activator of the microsomal phosphatase. It is pointed out that K+ is an essential requirement for HCl secretion in intact gastric mucosa and the replacement of K+ with Rb+, Cs+ and NH4+ is discussed. The K+‐stimulated phosphatase presented in this paper may play a role in the H+ secretion process.
The purine and pyrimidine metabolism of Tetrahymena pyriformis
Authors: Hill Donald L. , Chambers Patti 
Published: February 2005

AbstractThe metabolism of purines and pyrimidines by the ciliated protozoan Tetrahymena was investigated with the use of enzymatic assays and radioactive tracers. A survey of enzymes involved in purine metabolism revealed that the activities of inosine and guanosine phosphorylase (purine nucleoside: orthophosphate ribosyltransferase, E.C. 2.4.2.1) were high, but adenosine phosphorylase activity could not be demonstrated. The apparent Km for guanosine in the system catalyzing its phosphorolysis was 4.1 ± 0.6 × 10−3 M. Pyrophosphorylase activities for IMP and GMP (GMP: pyrophosphate phosphoribosyltransferase, E.C. 2.4.2.8), AMP (AMP: pyrophosphate phosphoribosyltransferase, E.C. 2.4.2.7), and 6‐mercaptopurine ribonucleotide were also found in this organism; but a number of purine and pyrimidine analogs did not function as substrates for these enzymes. The metabolism of labeled guanine and hypoxanthine by intact cells was consistent with the presence of the phosphorylases and pyrophosphorylases of purine metabolism found by enzymatic studies. Assays for adenosine kinase (ATP: adenosine 5'‐phosphotransferase, E.C. 2.7.1.20) inosine kinase, guanosine kinase, xanthine oxidase (xanthine: O2 oxidoreductase, E.C. 1.2.3.2), and GMP reductase (reduced‐NADP: GMP oxidoreductase [deaminating], E.C. 1.6.6.8) were all negative. In pyrimidine metabolism, cytidine‐deoxycytidine deaminase (cytidine aminohydrolase, E.C. 3.5.4.5), thymidine phosphorylase (thymidine: orthophosphate ribosyltransferase, E.C. 2.4.2.4), and uridine‐deoxyuridine phosphorylase (uridine: orthophosphate ribosyltransferase, E.C. 2.4.2.3) were active; but cytidine kinase, uridine kinase (ATP: uridine 5'‐phosphotransferase, E.C. 2.7.1.48), and CMP pyrophosphorylase could not be demonstrated.
Differential response of two derivatives of the BHK21 hamster cell to thymidine
Authors: Tobey R. A. , Petersen D. F. , Anderson E. C. 
Published: February 2005

AbstractAttempts to synchronize the BHK21 hamster cell C‐13 and its polyoma‐transformed derivative P‐183 with excess thymidine resulted in the observation that the parent cell line could be readily synchronized but the transformed derivative could not. Differences in the growth pattern indicate that excess thymidine (10 mM) stops progress of the virus‐transformed derivative at all stages in the life cycle rather than exclusively in S. The data are suggestive but do not establish that the difference is a result of the presence of the virus genome.
Synthesis of antibody by spleen cells after exposure to kiloroentgen doses of ionizing radiation
Authors: Makinodan T. , Nettesheim Paul , Morita Toshiteru , Chadwick Carol J. 
Published: February 2005

AbstractMouse spleen cells in diffusion chambers were studied in an effort to assess the radiation survival curves of lymphoid cells during the different serological phases of immune response and to characterize morphologically and metabolically these radiation‐resistant cells. The results showed that the capacity of immunocompetent progenitor cells to proliferate and differentiate into antibody‐synthesizing cells was highly sensitive to x‐irradiation. Their fully differentiated progenies, which were made up mainly of mature plasma cells, were resistant in that they were able to synthesize antibody effectively for as long as several days after their exposure to radiation doses up to 10,000 R.As a result of these studies, a method with a high recovery yield was devised for obtaining a highly purified preparation of dispersed monospecific antibody‐synthesizing cells. This was done by simply exposing primed spleen cells to 10,000 R at the end of the log phase of response and harvesting the culture several days later.
Studies on carcinogenesis by avian sarcoma viruses. VI. Differential multiplication of uninfected and of converted cells in response to insulin
Authors: Temin Howard M. 
Published: February 2005

AbstractInsulin can replace the factor(s) in calf serum whose amount is limiting for multiplication in cell culture of chicken embryo fibroblasts and of chicken embryo fibroblasts infected and converted by avian sarcoma virus. In serum‐free, insulin‐containing medium, converted cells multiply more than do uninfected cells. It appears, therefore, that the increased multiplication in cell culture of converted cells as compared with uninfected cells results from a decreased requirement by the converted cells for an insulin‐like activity found in serum.
RNA synthesis in synchronously growing populations of HeLa S3 cells. II. Rate of synthesis of individual RNA fractions
Authors: Pfeiffer S. E. 
Published: February 2005

AbstractThe rates of synthesis of various species of RNA were examined in synchronously growing HeLa cells as a function of stage in the cell generation cycle. The synthesis of each RNA species examined occurs throughout interphase, but undergoes a two‐fold increase in rate during early S which is dependent on the duplication of DNA; blocking the initiation of DNA synthesis also blocks the acceleration of RNA synthesis. To explain the data, a model is discussed in which the acceleration of RNA synthesis during early S is regulated by the number of active cistrons present; thus, as the genome is duplicated, more template is available for transcription, and the rate of RNA synthesis increases. Some implications of the model, and experimental evidence bearing on them, are also discussed.
Factors influencing hematopoietic spleen colony formation in irradiated mice. V. Effect of foreign plasma upon colony forming cell kinetics
Authors: Boggs D. R. , Marsh J. C. , Chervenick P. A. , Cartwright G. E. , Wintrobe M. M. 
Published: February 2005

AbstractForeign plasma injection induces a profound and somewhat complex change in the size and location of the colony forming unit (CFU) cell compartment. Injection of foreign plasma before irradiation induces an increase in CFU cells as judged by endogenous colonies as well as by a modification of the endogenous method which excludes spleen colony formation from in situ spleen cells. However, the enlargement does not take place in the most populous CFU cell areas, the spleen and marrow. The concentration and/or total number of CFU cells in spleen and marrow was not increased by plasma injection whether judged by the number of transplantable cells or by the number of migrating endogenous cells.These studies emphasize the complexity of this cellular system and suggest that the use of but one type of stem cell assay may yield results which do not reflect changes within the total compartment. Evidence for cell damage in vitro as a factor influencing results in studies involving transplantation was searched for but was not forthcoming.
The stimulation of tumor cell growth by a substance produced by normal and tumor cells
Authors: Ichikawa Yasuo , Paran Michael , Sachs Leo 
Published: February 2005

AbstractIt has been shown that a dialyzable substance produced by normal and tumor cells can stimulate the growth of a myeloid, erythroid, and two lymphoid leukemias, and a sarcoma. The growth stimulation of the tumor cells was observed as an increase in cloning efficiency and number of cells per colony. Rat granulocytes stimulated the growth of mouse tumor cells as efficiently as a variety of mouse cells. The stimulating substance was found in conditioned medium, and it was produced by all the normal and tumor cells tested.
Isolation of nuclei from mature peritoneal granulocytes
Authors: Lipke Herbert , Hester Ralph , Groff William , Petrali John 
Published: February 2005

AbstractNuclei from mature neutrophil granulocytes were prepared from peritonal exudates of goats. Fluorescein mercuric acetate was required to stabilize the nuclei and fix nucleoproteins. Following differential centrifugation and detergent treatment, electron microscopy showed the interlobar region to be free of cytoplasmic tabs. All of the DNA of the cell was recovered in the nucleus and 71% of the RNA. The DNA : RNA was 6 : 1 in the intact cells, and 9 : 1 in the isolated nuclei. Protein:DNA was 11 : 1 and 4 : 1 for cells and nuclei, respectively. Representative fractions of histones and tryptophan‐rich acidic proteins were prepared with (asp + glu) : (lys + arg + hist) values averaging 0.7 and 1.4 respectively. Histones accounted for 30% of the nuclear proteins while the residual proteins contained the bulk of the cystinyl residues. Granulocytes were characterized by high glycine titers, from 8 to 18% of the nuclear proteins, and 70% of the total free amino acids of the cell.
Recovery of cells in vitro from the effects of hypoxia and hyperoxia
Authors: Shaw David H. , Pace Donald M. 
Published: February 2005

AbstractThe cytotoxic effect of high, as well as low, oxygen tension of proliferation and metabolism of Low line cells in culture is reversible even after several days of exposure provided the cells are returned to 95% air + 5% CO2 environment. This suggests that the activity of certain mechanisms within the cells may have been altered or in other ways inhibited by the abnormal environments but are quite rapidly regenerated once the adverse condition is removed. The cells tolerate a low O2 exposure for at least 20 days while continuous exposure to high O2 atmosphere results in degeneration and death after 7–10 days. Both glucose utilization and lactic acid production are elevated in cultures exposed to either low or high O2 tensions, although they are markedly higher in the latter condition. When cell so exposed are returned to an air + 5% CO2 atmosphere, rate of glucose uptake and lactic acid formation soon approaches that found in control cultures.
Differences between exogenous and endogenous hemopoietic spleen colonies
Authors: Jenkins V. K. , Upton A. C. , Odell T. T. 
Published: February 2005

AbstractHistologic examination of the spleens in RFM/Un mice killed 6 to 9 days after 350 to 800 R whole‐body x‐irradiation revealed hemopoietic colonies, the numbers of which decreased exponentially with increasing radiation dose. In such animals, myelocytic colonies were the predominant type on the sixth to the eighth day. However, they decreased in number with time, being fewer than erythropoietic colonies by the ninth day after irradiation. In C57BL mice, erythropoietic colonies were relatively more numerous, markedly predominating on both the eighth and the thirteenth days.RFM/Un mice injected with nonirradiated syngeneic bone marrow cells within 24 hours after 750 R developed colonies, predominantly of erythropoietic and undifferentiated types, the numbers of which were proportional to the numbers of marrow cells injected. The number of colonies formed from exogenous marrow cells increased slightly between the sixth and ninth days after inoculation, possibly because of a greater likelihood of counting them due to an increase in their size.
Thymidine as a synchronizing agent. II. Partial recovery of HeLa cells from unbalanced growth
Authors: Lambert W. Clark , Studzinski George P. 
Published: February 2005

AbstractRandomly growing cultures of HeLa‐S3 cells were subjected to synchronizing treatment with excess thymidine. Unbalanced growth occurred during the thymidine treatment, but the abnormal cellular composition was found to revert to control levels so that at the time of the first mitosis following a 12–24 hour treatment with the inhibitor the cellular DNA, RNA and protein content and cell size were close to control values. However, an alkaline deoxyribonuclease which attacks denatured DNA was still found to be significantly elevated at this time. The results argue against the use of thymidine as a synchrony producing agent.
Macromolecular synthesis, differentiation and cell division in Tetrahymena pyriformis mating type I variety 1
Authors: Gavin Ray H. , Frankel Joseph 
Published: February 2005

AbstractIn Tetrahymena pyriformis, mating type I, variety 1, cycloheximide rapidly and completely inhibited incorporation of 14C‐L‐leucine into protein. Actinomycin D (25 μg per ml) inhibited incorporation of 14C‐uracil into cold‐TCA‐insoluble material, after a 5–10 minute lag. Frequently a subsequent decline in the amount of radioactivity was observed. Protein synthesis continued in actinomycintreated cultures for a variable time after cessation of RNA synthesis.Oral development was affected by cycloheximide virtually immediately, and by actinomycin D after a 10–15 minute lag. Cells affected by either drug before the onset of oral membranelle formation were permanently arrested in the stomatogenic field phase. Cells affected in the early and middle stages of membranelle formation completed development of membranelles, but did not invariably complete cell division. Cycloheximide, when added at the beginning of membranelle formation, brought about arrest or resorption of membranelles after they were completed. Actinomycin did not elicit resorption, but sometimes brought about blockage during cell division. Cells affected by either drug after membranelles were fully formed (and cell division was just beginning) completed oral development, nuclear divisions, and cell division. These results suggest that concurrent RNA and protein synthesis are essential for the initiation but not for the completion of membranelle differentiation. The results also suggest that a specific messenger RNA(s) with a very short half‐life is required for the synthesis of proteins involved in the initiation of membranelle differentiation.
The effect of polyamines on cell culture cells
Authors: Higgins M. Louise , Tillman M. Constance , Rupp James P. , Leach Franklin R. 
Published: February 2005

AbstractGrowth of KB cells was inhibited by both spermine and spermidine, but the inhibition is reduced in conditioned medium. The amount of spermine required for 50% inhibition of plating varied according to the type of serum used with medium 199 (calf, fetal bovine, and horse; 0.55, 0.9, and 24 μg/ml respectively). The spermine oxidase activity of the three sera was calf > horse > fetal bovine, which is not the same ordering as was obtained for the inhibition. When the concentration of sera in the media was varied, the inhibition decreased as calf and fetal bovine sera concentration increased, whereas, with horse serum, an increase in serum concentration increased the inhibition. The opposite effects of increasing concentrations of the sera on the inhibition suggest that at least two factors are involved in the inhibition. A scheme which involves three factors (spermine oxidase, another enzyme and its activator) is postulated to account for the inhibitions and reversals observed. Spermine oxidase alone cannot account for the action of polyamine on cells.
Reversible inhibition of ribosomal RNA synthesis in HeLa by lucanthone (Miracil D) with continued synthesis of DNA‐like RNA
Authors: Bases Robert , Mendez Frances 
Published: February 2005

AbstractRibosomal RNA synthesis was selectively inhibited in HeLa cells by lucanthone, a clinically useful schistosomicide which shares many of the properties of Actinomycin D. Synthesis of DNA‐like RNA continued during complete inhibition of ribosomal RNA synthesis. Under these conditions newly synthesized DNA‐like RNA accumulated normally in polyribosomes of the cell cytoplasm; most of it appeared to be messenger RNA. DNA synthesis was partially inhibited by lucanthone but protein synthesis was undisturbed. Synthesis of ribosomal RNA promptly resumed after removal of lucanthone and cell survival was not affected if exposures to the drug were limited to two hours.