Showing papers on "Growth medium published in 1981"
TL;DR: Results indicate that when grown to stationary phase in media containing high concentrations of certain sugars, C. albicans undergoes a change in cell surface composition which facilitates its adherence to acrylic surfaces.
Abstract: The adherence of Candida albicans to acrylic was measured in vitro after growth of the yeast to stationary phase in defined medium containing glucose, sucrose, galactose, fructose, or maltose as the carbon source. In each case, yeast adherence was proportional to the concentration of sugar in the growth medium, but equimolar concentrations of different sugars promoted adherence to different extents. In vitro adherence was further increased by the addition of divalent cations to assay mixtures but was inhibited when saliva-treated acrylic strips were used or when yeasts were suspended in mixed saliva during the assay. The rate of spheroplast formation of yeasts grown in media containing a 500 mM concentration of the different sugars correlated well with the relative adherence of the cells to acrylic. Galactose-grown yeasts were most resistant to spheroplast formation with Zymolyase-5000 and most adherent to acrylic, whereas fructose-grown organisms were least resistant to spheroplast formation and least adherent to acrylic. These results indicate that when grown to stationary phase in media containing high concentrations of certain sugars, C. albicans undergoes a change in cell surface composition which facilitates its adherence to acrylic surfaces. Electron microscopy of yeasts harvested from such media revealed the presence of an additional surface layer which may be responsible for this enhanced adherence.
242 citations
TL;DR: It is demonstrated that, at least on minimal medium plates, membrane damage contributes significantly towards cell killing, and the large variability often observed in near‐UV radiation survival data, is largely oxygen dependent.
Abstract: A DNA repair competent strain of Escherichia coli K-12 showed sensitivity to inorganic salts (at concentrations routinely used in minimal media) after irradiation with broad spectrum near–UV radiation, at fluences that caused little inactivation when plated on complex growth medium. This effect was not observed with cells that had been exposed to 254 nm radiation. This sensitivity to minimal medium was increased by increasing the salt concentration of the medium and by increasing the pH of the medium. This sensitivity was greatly increased by adding to the medium a low concentration of commercial glassware cleaning detergent that had no effect on unirradiated cells or far-UV irradiated cells. These findings may explain the large variability often observed in near-UV radiation survival data, and demonstrate that, at least on minimal medium plates, membrane damage contributes significantly towards cell killing. This phenomenon is largely oxygen dependent.
96 citations
TL;DR: Ten strains of Caldariomyces fumago and related fungi were found to produce extracellular chloroperoxidase when grown on a glucose - malt extract medium which provided a defined medium which, by comparison with the complex medium, produced the following results with both fungal strains.
Abstract: Ten strains of Caldariomyces fumago and related fungi were found to produce extracellular chloroperoxidase when grown on a glucose – malt extract medium. High enzyme levels and pigment production were observed for C. fumago ATCC 16373 and C. fumago CMI 89362. Removal of malt extract from the medium and the replacement of glucose by fructose as the carbon source provided a defined medium which, by comparison with the complex medium, produced the following results with both fungal strains. Chloroperoxidase was produced to similar levels, with maximum production after 6 days rather than 12 days of growth; pigmentation of the medium was reduced by 90% and the pH of the medium remained constant, thus stabilizing enzyme activity. Addition of urea or proline as a nitrogen supplement to nitrate enhanced enzyme production by strain CMI 89362. Comparison of the two strains indicated that CMI 89362 produced higher levels of chloroperoxidase than ATCC 16373.
54 citations
Patent•
07 May 1981
TL;DR: In this article, the authors described a method for isolating and culturing human mammary epithelial cells of both normal and malignant origin, which is suitable for a quantitative assessment of the cytotoxicity of particular treatment.
Abstract: Methods are disclosed for isolating and culturing human mammary epithelial cells of both normal and malignant origin. Tissue samples are digested with a mixture including the enzymes collagenase and hyaluronidase to produce clumps of cells substantially free from stroma and other undesired cellular material. Growing the clumps of cells in mass culture in an enriched medium containing particular growth factors allows for active cell proliferation and subculture. Clonal culture having plating efficiencies of up to 40% or greater may be obtained using individual cells derived from the mass culture by plating the cells on appropriate substrates in the enriched media. The clonal growth of cells so obtained is suitable for a quantitative assessment of the cytotoxicity of particular treatment. An exemplary assay for assessing the cytotoxicity of the drug adriamycin is presented.
46 citations
TL;DR: The results suggest that the morphology of the L. acidophilus cell may be an important consideration in the preparation of freeze-stable culture concentrates, and the bacilloid cells were more resistant to freezing and storage at conventional freezer temperatures.
Abstract: Examination of factors affecting the resistance of Lactobacillus acidophilus NCFM culture concentrates to freeze injury induced during frozen storage at -20°C revealed that calcium supplementation of the growth medium contributed to the storage stability of cells prepared in static culture. Culture concentrates of L. acidophilus NCFM were prepared from cells propagated in MRS broth or MRS broth supplemented with 0.1% calcium carbonate, calcium chloride, or calcium phosphate. After 28 days of frozen storage at -20°C, concentrated cells (3.2 × 10 9 colony-forming units per ml) prepared from MRS broth cultures showed an 84% reduction in viable cells. Of the remaining viable cells, 88% were sublethally injured and unable to form colonies on MRS agar supplemented with 0.15% bile. Cells prepared in calcium-supplemented MRS broths demonstrated more resistance to frozen storage. Viability and injury losses in the frozen concentrates were limited to 10 to 39% and 3 to 23%, respectively. It was observed that calcium supplementation of MRS medium resulted in a morphological transition of L. acidophilus NCFM from filamentous to bacilloid rods, and the bacilloid cells were more resistant to freezing and storage at conventional freezer temperatures. The results suggest that the morphology of the L. acidophilus cell may be an important consideration in the preparation of freeze-stable culture concentrates. Images
37 citations
TL;DR: The effect of CO2+ on the synthesis and activation of Bacillus licheniformis MC14 alkaline phosphatase has been shown by the development of a defined minimal salts medium in which this organism produces 35 times more alkalineosphatase than when grown in a low-phosphate complex medium or in the defined medium without cobalt.
Abstract: The effect of CO2+ on the synthesis and activation of Bacillus licheniformis MC14 alkaline phosphatase has been shown by the development of a defined minimal salts medium in which this organism produces 35 times more (assayable) alkaline phosphatase than when grown in a low-phosphate complex medium or in the defined medium without cobalt. Stimulation of enzyme activity with cobalt is dependent on a low phosphate concentration in the medium (below 0.075 mM) and continued protein synthesis. Cobalt stimulation resulted in alkaline phosphate production being a major portion of total protein synthesized during late-logarithmic and early-stationary-phase culture growth. Cells cultured in the defined medium minus cobalt, or purified enzyme partially inactivated with a chelating agent, showed a 2.5-fold increase in activity when assayed in the presence of cobalt. Atomic spectral analysis indicated the presence of 3.65 +/- 0.45 g-atoms of cobalt associated with each mole of purified active alkaline phosphatase. A biochemical localization as a function of culture age in this medium showed that alkaline phosphatase was associated with the cytoplasmic membrane and was also found as a soluble enzyme in the periplasmic region and secreted into the growth medium.
34 citations
TL;DR: The phenomenon of drug adaptation in Tetrahymena, at least with respect to cycloheximide, is associated with this ribosome phosphorylation, and enzymatic removal of this phosphate converts "starved cell" ribosomes into "growing cell" Ribosomes.
31 citations
TL;DR: There was a significant amount of dopamine in the growth medium from stationary-phase cultures and, to a lesser extent, logarithmic-phase cells.
27 citations
TL;DR: Results are consistent with the conclusion that D. discoideum exhibits two types of pinocytotic activity: one that is nutrient dependent and the other independent of nutrients, which persists in starvation medium and is unaffected by hadacidin.
Abstract: In the present study we examine the effects of the drug hadacidin (N-formyl-N- hydroxyglycine) on pinocytosis in the eukaryotic microorganism dictyostelium discoideum. At concentrations of up to approximately 8 mg/ml, hadacidin inhibited the rate of pinocytosis of fluorescein isothiocyanate (FITC) dextran in cells in growth medium in a concentration-dependent manner but had no effect on cells in starvation medium. Because hadacidin also inhibits cellular proliferation at this concentration, the relationship between growth rate and pinocytosis was studied further using another drug, cerulenin, to produce growth-arrest. These experiments showed no changes in the rate pinocytosis even after complete cessation of cellular proliferation. Other studies showed that the transfer of cells from growth to starvation medium reduced the rate of pinocytosis by approximately 50 percent. A reduction of similar magnitude occurred if cells were transferred from growth to starvation medium containing hadacidin. Also, no additional reduction in pinocytosis occurred when cells that had been treated with hadacidin were transferred to starvation medium containing hadacidin. These cells were able to take up [(14)C]hadacidin in the starvation medium. In contrast to the results with hadacidin-treated cells, cells in a cerulenin-induced state of growth-arrest when transferred to starvation medium exhibited the same 50 percent reduction in pinocytosis observed in cells not previously exposed to either drug. Cells treated with azide, in either growth or starvation medium, exhibited an immediate inhibition of all pinocytotic activity. After the transfer of log-phase cells to starvation medium supplemented with glucose, the reduction in rate was only approximately 10-15 percent. In contrast, a 50 percent reduction was observed after supplementation of starvation medium with sucrose, KCl, or concanavalin A. Maintaining the cells in growth medium containing hadacidin for as long as 16 h had no effect on the rate at which cells aggregated. These results are consistent with the conclusion that D. discoideum exhibits two types of pinocytotic activity: one that is nutrient dependent and the other independent of nutrients. This latter activity persists in starvation medium and is unaffected by hadacidin, whereas the nutrient-dependent activity is present in growth medium and is inhibited by hadacidin.
26 citations
TL;DR: It is demonstrated for the first time that normal mammary cells can be maintained in a functional hormone-responsive state for extended periods in primary cell culture.
Abstract: Mammary cells from normal tissue of virginal, pregnant, and lactating rats have been adapted to long term monolayer culture in plastic culture dishes with retention of hormone-responsive functional activity. The addition of PRL, insulin, and corticosterone resulted in an increase in the proportion of epithelial cells, the development of intracellular lipid droplets, and the ordered aggregations of these cells. In the presence of these hormones, the milk protein, a-lactalbumin (a-LA), was secreted into the growth medium at rates of 20–100 ng/mg cellular protein-24 h. A double antibody RIA for a-LA capable of measuring 0.1 ng a-LA/100 μl growth medium was developed in our laboratory for these studies. Both intracellular and extracellular a-LA fell below detectability within 2-3 weeks after hormone withdrawal. Intracellular a-LA accounted for less than 3% of the total a-LA accumulated in each culture in 24 h. The production rate of cells continuously given hormones increased 4- to 7-fold over a period of sev...
23 citations
TL;DR: Studies of the marine bacterium Alteromonas haloplanktis 214 showed that as the Na+ concentration in the growth medium decreased from 230 to 34 mM, the lowest concentration permitting growth, the length of the lag period preceding exponential growth increased.
Abstract: Studies of the marine bacterium Alteromonas haloplanktis 214 (formerly referred to as marine pseudomonad B-16) showed that as the Na+ concentration in the growth medium decreased from 230 to 34 mM, the lowest concentration permitting growth, the length of the lag period preceding exponential growth increased. Once growth had begun, except for a slight reduction in rate of growth at 34 mM Na+, the generation time and extent of growth remained essentially constant over the range of Na+ concentrations tested. Plate counts showed that during the lag period the numbers of viable cells introduced as inoculum into a complex medium containing 33 mM Na+ decreased exponentially before increasing. Repeated subculture of the cells at 33 mM Na+ failed to eliminate the lag period or reduce the loss of viability of the cells. The viability loss and the lag period could be eliminated either by raising the NaCl concentration to 130 mM or by adding sufficient sucrose to make the osmotic pressure of the medium equal to that obtained by adding 130 mM NaCl. In a chemically defined medium, sucrose added to maintain tonicity reduced but did not eliminate the lag periods obtained at suboptimal Na+ concentrations. Increasing the number of cells plated on trypticase agar medium reduced the Na+ concentration required to permit growth. Evidence was obtained of a requirement of A. haloplanktis for Ca2+ for growth. Ca2+ spared to a small extent the requirement for Na+ for growth. Some 10(10) cells of a histidine-requiring, streptomycin-resistant mutant of A. haloplanktis 214, still viable after treatment with N-methyl-N'-nitro-N-nitrosoguanidine, were screened for capacity to grow in the absence of Na+. Since no non-Na+-requiring mutants were isolated, the requirement of this organism for Na+ would appear to be extremely stable.
TL;DR: The results suggest that both uptake of F into cells and their susceptibility to F inhibition vary with their metabolic state, which is not explained by an effect of pH on F inhibition of enolase which is believed to be the inhibitory site of F in cells.
TL;DR: The results indicate that ALA synthetase is not required for growth and bacteriochlorophyll synthesis in H5D and that γ,δ-dioxovaleric acid is probably not an intermediate in the formation of δ-aminolevulinic acid in the strains of Rhodopseudomonas sphaeroides studied.
01 Sep 1981
TL;DR: A strain ofFusarium moniliforme, previously used for microbial protein production, excreted lactase (β-D-galactosidase, EC.3.2.1 23) when cultivated either in a whey liquid medium or on a wheat bran solid medium and was particularly suitable for processing acid whey.
Abstract: A strain ofFusarium moniliforme, previously used for microbial protein production, excreted lactase (β-D-galactosidase, EC.3.2.1 23) when cultivated either in a whey liquid medium or on a wheat bran solid medium. The enzyme produced in both media had pH and temperature optima of 4–5 and 50–60°C respectively and was particularly suitable for processing acid whey. In the whey culture, maximum lactase yield was observed after 95 h of growth at 30°C and whey lactose concentration of 9%. The addition of ammonium, potassium and sodium ions to the growth medium considerably enhanced lactase production. A maximum enzyme yield corresponding to hydrolysis of 3 nmoles o-nitrophenyl-β-D-galactopyranoside sec−1 ml−1 of growth medium, at pH 5 and 60°C, was obtained. In the wheat bran culture, the maximum enzyme yield was obtained after 140 h of growth at 28–30°C. A marked increase in the enzyme production was observed when nitrate or phosphate was added to the growth medium. Also, the addition of certain agricultural by-products (molasses, whey) enhanced lactase production. The observed maximum yield corresponding to the hydrolysis of 182 nmoles of ONPG sec−1 g−1 of wheat bran, at pH 5 and 60°C, is comparable to that reported for certain microorganisms used commercially for lactase production.
TL;DR: A culture medium and culture conditions are described that enable generative cell division and sperm formation to occur in a large proportion (greater than 70%) of the pollen tubes of Tradescantia paludosa within six to eight hours of culture of pollen.
Abstract: A culture medium and culture conditions are described that enable generative cell division and sperm formation to occur in a large proportion (greater than 70%) of the pollen tubes of Tradescantia paludosa within six to eight hours of culture of pollen. The nature of the nitrogen source, speed of shaking, and ratio of pollen to medium are important parameters in determining the extent of sperm formation. Addition of the plant hormones indole acetic acid, gibberellic acid, and kinetin to the growth medium does not influence generative cell division.
Journal Article•
TL;DR: Two serum-free media (a minimal synthetic medium and a high-density synthetic medium) are described that support the growth and differentiation of human K562(S) and mouse clones 745, 707, and 3TCl 12 erythroleukemia cell lines in long-term culture.
Abstract: Only two chemicals (transferrin and selenium dioxide) are required to supplement serum-free Roswell Park Memorial Institute Medium 1640 for long-term growth and for spontaneous and induced differentiation of established lines of human and mouse erythroleukemia cells. We describe here two serum-free media (a minimal synthetic medium and a high-density synthetic medium) that support the growth and differentiation of human K562(S) and mouse clones 745, 707, and 3TCl 12 erythroleukemia cell lines in long-term culture. The doubling times of the erythroleukemic cell populations are longer in minimal synthetic medium that in serum-containing medium. Cell saturation density in minimal growth medium is one-half that obtained in serum-containing medium for clone 745, whereas for K562(S) it is approximately the same. Cell saturation density in high-density medium (containing albumin) is greater than that achieved in serum-containing medium for K562(S), whereas for clone 745 cell saturation density increases for cells in midlogarithmic growth, although not to the density of cells grown in serum-containing medium. The differences in saturation density are due to a decreased doubling time as well as to better survival of the cells 3 or 4 days after plating. The cells can grow in the synthetic media and be passaged for as many generations as desired without impairment of growth capabilities. In the minimal synthetic medium, spontaneous differentiation of erythroleukemia cells continues to occur, indicating that spontaneously differentiating cells are the result of intracellular mechanisms controlling the expression of a genetic program of some of the cells at any given time. Hemoglobin synthesis can be induced in cells growing in synthetic medium by using lower concentrations of the same inducers that are effective in serum-containing medium, indicating that these chemicals do not depend on serum factors to initiate the process of differentiation. The percentage of benzidine-positive cells and the concentration of hemoglobin per cell, however, are less in the synthetic medium than in serum-containing medium, suggesting that serum factors do play a role in modulating the extent of hemoglobin synthesis. The types of hemoglobins synthesized by cells in synthetic medium are identical to those reported in serum-containing medium.
TL;DR: The nonfat dry milk filtrate is inexpensive, is easily prepared, and is a substitute for serum in epithelial cell culture media.
Abstract: A number of milk types and milk fractions were investigated as possible substitutes for serum in cell culture media. A filtrate of reconstituted nonfat dry milk showed promise. Culture fluids containing 5% of the nonfat dry milk filtrate were used to propagate primary and continuous cell cultures, and the cell growth from these cultures was compared with that of cells grown in a serum-containing medium. The nonfat dry milk filtrate-supplemented medium supported the growth of all epithelial cells tested, but two fibroblast-type cultures failed to replicate. Cells grown in the medium containing the milk filtrate grew slowly for 2 to 3 days and then propagated to confluency in 6 to 8 days. Viable cell counts of 9 days were comparable to those of serum-grown cells that had been propagated for 7 days. Cells grown in the milk filtrate could be split 1 to 4 when subcultures were prepared. Cell growth could be stimulated by refeeding on days 2 to 3 or by the addition of 30 microM 2-mercaptoethanol to the growth medium. Virus susceptibility and titer comparisons with poliovirus 1, coxsackievirus B2, echovirus 7, and herpes simplex virus indicated that approximately the same data were obtained when either the nonfat dry milk filtrate-treated or the serum-treated cells were studied. The nonfat dry milk filtrate is inexpensive, is easily prepared, and is a substitute for serum in epithelial cell culture media.
TL;DR: There is a novel proline transport system in S. typhimurium which is activated in media of elevated osmolarity, and putP- proP- double mutants, which lack both of the known proline permeases are resistant in minimal medium to the toxic proline analogues 3,4-dehydro-D, L-proline and L-azetidine-2-carboxylate.
Abstract: A variety of strategies have evolved for the regulation of the internal osmotic strength of organisms, but the details of these osmoregulatory mechanisms are poorly understood. In bacteria, internal osmolarity is maintained mainly by the accumulation of amino acids (3,10,16) and inorganic ions (4,9), such that it exceeds the osmolarity of the growth medium. A discovery made a quarter of a century ago by J. H. B. Christian suggested that proline has a special role in osmoregulation: in media of inhibitory osmolarity the growth and respiration rates of Salmonella orianenburg were stimulated specifically by the addition of proline (5,6). Using this observation as motivation, we have selected proline overproducing mutants of Salmonella typhimurium and found that some, as a result, have acquired an increased growth rate in media of inhibitory osmolarity (8; L. Csonka, manuscript in preparation). We found that in these proline over-producing mutants, the intracellular proline levels were regulated such that they increased with increasing osmotic stress. Here, we present experimental results which suggest that in the over-producing mutants, and in wild type strain, the proline permeases play an important role during osmotic stress for the regulation of the intracellular proline levels.
TL;DR: The growth of the pm nbg mutant strain of Neurospora crassa was inhibited by the amino acid analog para-fluorophenylalanine despite the fact that none of the three constitutive amino acid permeases is functional in this strain, leading to the detection of both a deaminase and a keto acid transport system.
Abstract: The growth of the pm nbg mutant strain of Neurospora crassa was inhibited by the amino acid analog para-fluorophenylalanine despite the fact that none of the three constitutive amino acid permeases is functional in this strain. This observation led to the detection of both a deaminase which was released into the growth medium in response to para-fluorophenylalanine and a keto acid transport system which allowed entry of the resulting keto acid into the cell. The transported keto acid was recovered in cellular protein, suggesting its regeneration as the amino acid. The cooperative activity of these two systems represents an additional mechanism for the intracellular accumulation of amino acids, which is distinct from the known amino acid permeases.
TL;DR: It is demonstrated that compared to growth of cells in serum‐free medium, growth in serum-containing medium can inhibit expression of cell surface β‐adrenergic receptors, implying that the presence of serum in medium in which cells are grown alters properties in the plasma membrane and may alter hormonal responses in such cells.
Abstract: Rat C6 glioma cells were grown in 5% fetal bovine serum-containing medium and under serum-free, defined conditions. In order to ask whether cells grown in serum-free medium are phenotypically identical to cells grown in serum, we examined effects of cell growth under both conditions on the beta-adrenergic receptor, a cell surface marker that activates adenylate cyclase and thereby regulates these cells. beta-Adrenergic receptors were qualitatively similar in cells grown in serum-containing and serum-free media, but the number of receptors was 30-50% less in cells grown with serum. This effect required several days to occur or to be reversed. The decreased number of receptors appeared to be caused by an inhibitory effect of serum on receptor number and not by a stimulatory action of the constituents of the serum-free medium. Growth medium with 5% fetal bovine serum maximally inhibited beta-adrenergic receptor numbers with 1% serum causing a half-maximal inhibition. The ability of serum to inhibit the expression of beta-adrenergic receptors could be blocked by dialyzing but not by boiling fetal bovine serum. beta-Adrenergic receptor-stimulated cyclic AMP accumulation was also decreased by growth in medium containing serum. These studies demonstrate that compared to growth of cells in serum-free medium, growth in serum-containing medium can inhibit expression of cell surface beta-adrenergic receptors. These results imply that the presence of serum in medium in which cells are grown alters properties in the plasma membrane and may alter hormonal responses in such cells.
TL;DR: The cell populations derived from these colonies, when propagated and injected into the nude mice, formed myxofibromas at the injection sites rather than the type of tumor (fibrosarcoma) previously described for chemical carcinogen-induced neoplasms.
TL;DR: It is suggested that galactofuranosidase activity is destroyed by acid protease(s) and that gal ACTO activity appears in the medium only after it is depleted of glucose and sufficient organic acid has been taken up to increase the pH of the medium above 4.
TL;DR: The profound increase in the total fatty acid content of palmitic acid-grown cells altered neither sensitivity to tetracycline or erythromycin nor the amount of hydrogen peroxide secreted.
Abstract: The fatty acid content of Mycoplasma pneumoniae increased 2.5- to 9.6-fold when the growth medium was supplemented with a saturated, unsaturated, or beta-hydroxy fatty acid, the greatest increase occurring with palmitic acid. The amount of each supplemented fatty acid found within this organism was 2.8 to 5.5% of the total fatty acid content; the exception was palmitic acid. Up to 57% of the palmitic acid was utilized from the supplemented medium, whereas only 0.2 to 10% of the other fatty acids was utilized. Chromatographic and isotopic analyses revealed that 22% of the labeled palmitic acid incorporated from the palmitic acid-supplemented medium remained free in this organism. Also, even though complex lipid synthesis increased a minimum of 3.8-fold under these conditions, this mycoplasma continued to incorporate intact complex lipids from the growth medium. Bacteriostatic and bactericidal studies which used high concentrations of various long-chain fatty acids showed that only palmitic, myristic, and beta-hydroxydecanoic acids were not bactericidal. The addition of palmitic acid to the growth medium resulted in the formation of exceedingly long, filamentous cells in approximately 25% of the population. Osmotic fragility and electron spin resonance spectroscopy studies showed a correlation among this increased fatty acid content, decreased membrane fluidity, and the increased osmotic fragility of palmitic acid-grown cells. In addition, these cells had a lowered cholesterol content. The effect of such compositional changes on osmotic fragility is discussed in this paper. Finally, the profound increase in the total fatty acid content of palmitic acid-grown cells altered neither sensitivity to tetracycline or erythromycin nor the amount of hydrogen peroxide secreted. Images
TL;DR: Tumorigenic clonal lines derived from soft agar colonies induced by DMBA‐transformed feline embryo cells were isolated and characterized, the morphologically altered clonal cells formed large aggregates and produced progressively growing sarcomas.
Abstract: Tumorigenic clonal lines derived from soft agar colonies induced by DMBA-transformed feline embryo cells were isolated and characterized. The morphologically altered clonal cells formed large aggregates, growing in this aggregate form when suspended in liquid growth medium above an agar base and forming colonies in soft agar with high efficiency. When inoculated into athymic nude mice, chemically altered clonal cells produced progressively growing sarcomas. Cells established from the tumors morphologically resembled the DMBA-transformed feline embryo cells and were characterized as cat cells by karyological analysis. The tumorigenic lines were negative for feline oncornavirus-associated cell membrane antigen (FOCMA), and for "gag-X" the transformation-related polyprotein which is encoded by the replication defective feline sarcoma virus.
TL;DR: Wheat bran was the best cereal by-product forSCP production and compared favourably with glucose as a carbon source for SCP production by A. niger and A. terreus grown on wheat-bran medium.
Journal Article•
TL;DR: The results of the temperature growth/electrophoresis experiments support the view that a sharp change in membrane fluidity occurs in the yeast membrane and indicate the profound importance of the cell surface in the interaction with the antibiotic.
Abstract: The electrophoretic behaviour of fresh and liquid nitrogen stored inocula of Saccharomyces cerevisiae has been studied as a function of pH, ionic strength, buffer composition, growth temperature of the inoculum, number of washings of the inoculum prior to electrophoretic investigation, growth medium used in the preparation of the inoculum, interaction of the inoculum with nystatin, and interaction of the inoculum with calcium ions. The results provide a basis for a discussion of the role of the yeast cell surface in the mode of action of nystatin (a polyene antibiotic), on interaction with sensitive Saccharomyces cerevisiae cells. They indicate the profound importance of the cell surface in the interaction with the antibiotic. Moreover, the results of the temperature growth/electrophoresis experiments support the view that a sharp change in membrane fluidity occurs in the yeast membrane. The results are also discussed in the light of those reported in previous papers on the interaction of yeast cells with nystatin.
TL;DR: Growth, hydrogen production and cellulose digestion by Acetivibrio cellulolyticus strain CD2 were considerably greater when the culture pH was maintained at 70 than when the pH was not controlled.
Abstract: Growth, hydrogen production and cellulose digestion by Acetivibrio cellulolyticus strain CD2 were considerably greater when the culture pH was maintained at 70 than when the pH was not controlled. Furthermore, if the pH of the growth medium was controlled the number of viable organisms was 6-fold greater after 3 d incubation and 100-fold greater after 6 d incubation compared with equivalent cultures in which the pH was not controlled. The differences were due to the combined effect of low pH values and acetic acid accumulation. The number of viable organisms was 2- to 3-fold lower after 12 h incubation in substrate-free medium containing 40 mm-acetic acid at pH 55 than in the same medium at pH 70. Addition of 90 mm-acetic acid during growth in a cellobiose-containing medium lowered the growth rate by 30% and the rate of hydrogen production by 40%. Exposure of A. cellulolyticus to oxygen for up to 2 h did not affect viability measurements provided that the organisms were subsequently transferred to reduced media.
TL;DR: The presence or absence of bicarbonate is without effect on chick embryo fibroblast proliferation over a 6‐day growth period and both lactic acid accumulation per mole of glucose consumed and the utilization of glutamine increase as a function of bismuth ion in the growth medium.
Abstract: The amount of glucose consumed by chick embryo fibroblasts in primary culture is strongly influenced by the presence of bicarbonate ion in the culture medium. Cells grown on glucose at physiologic concentration (5.5 mm) and in the absence of bicarbonate ion have a reduced rate of glucose utilization when compared to their counterparts cultivated in medium containing the usual 25 mM bicarbonate. The presence or absence of bicarbonate is without effect on chick embryo fibroblast proliferation over a 6-day growth period. Both lactic acid accumulation per mole of glucose consumed and the utilization of glutamine increase as a function of bicarbonate ion in the growth medium.
TL;DR: It is concluded that isolates 458 and 521 are representatives of two distinct physiological races of E. egressa.
Abstract: Isolate 458 of Entomophthora egressa from larvae of the eastern hemlock looper and isolate 521 from larvae of the spruce budworm differed in colony morphology on coagulated egg yolk medium, protoplast growth rate in modified Grace's medium, regeneration sequence, effect on growth medium [pH, osmolality, individual and total ninhydrin-positive compound (NPC) levels, total protein and glucose concentration], rate of glucose uptake, protein synthesis, degree of amino acid utilization and growth response to CO2. The major NPC utilized included t.-aspartic acid, iL-glutamic acid, L-lysine, L-histidine, L-tyrosine, L-leucine, L-valine, I-glutamine, glycine, DL-serine and /3-alanine. The major endogenous protoplast NPC were L-glutamic acid, L.histidine, L-alanine, DLt.-serine and glycine with moderate levels of L.-aspartic acid, t-arginine, i.-proline, t.-glutamine, tL-asparagine and /f-alanine. As a result of the observed developmental and physiological differences, we conclude that isolates 458 and 521 are representatives of two distinct physiological races of E. egressa.
TL;DR: Findings suggest that MeSH is an intermediate product between L-methionine and MeSAc, but its formation was dramatically inhibited by copper ions.
Abstract: S-Methyl thioacetate (MeSAc) production by brewer's yeast from methyl mercaptan (MeSH) was investigated under various conditions. At optimum, 98 mg/liter of MeSAc was produced from 500mg/liter of MeSH contained in culture broth. The MeSAc level in yeast growth medium was increased with increasing MeSH at relatively low levels (10 to 500 mg/liter). However, higher MeSH levels in medium (over 1 g/liter) inhibited yeast growth, and no MeSAc was produced. MeSAc was formed readily by incubating MeSH with yeast resting cells. Furthermore, S-ethyl or S-n-propyl thioacetate accumulated in yeast cell suspension when ethyl or n-propyl mercaptan, respectively, was incubated with resting cells. MeSAc was also produced from L-methionine by brewer's yeast, but its formation was dramatically inhibited by copper ions. This finding suggests that MeSH is an intermediate product between L-methionine and MeSAc.