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Showing papers on "Growth medium published in 1977"


Journal ArticleDOI
TL;DR: Chick embryo fibroblasts transformed by Rous sarcoma virus have an increased content of two membrane proteins of molecular weights 78,000 and 95,000 which may have an important role in regulating the utilization of glucose in cultured cells.
Abstract: Chick embryo fibroblasts transformed by Rous sarcoma virus have an increased content of two membrane proteins of molecular weights 78,000 and 95,000. The increased content of the 95,000-dalton protein and the principal increase in the content of the 78,000-dalton protein are not an early consequence of cell transformation but instead are secondary to the rapid depletion of glucose from the growth medium of transformed cells. When glucose is maintained at high levels in the growth medium of transformed cells, the synthesis of the 95,000-dalton protein is arrested and that of the 78,000-dalton protein is markedly suppressed. Upon removal of glucose from the growth medium of normal cells, these proteins increase to levels comparable to those of transformed cells. Because the amount of these two proteins is influenced by the presence or absence of glucose, we suggest they be referred to as "glucose-regulated proteins." GRP-78 and GRP-95. These proteins may have an important role in regulating the utilization of glucose in cultured cells.

364 citations


Journal ArticleDOI
TL;DR: Kinetic studies showed that, after the osmolarity of the medium was changed, one protein was hardly incorporated into the membrane, whereas the other was incorporated with an increased rate, and both proteins were subsequently incorporated in the cell ensured this new ratio.
Abstract: Supplementation of the growth medium with high concentrations of NaCl, KCl, or sucrose caused a drastic change in the ratio of the two peptidoglycan-associated major outer membrane proteins of Escherichia coli K-12 in that the amounts of proteins b and c present in cell envelope preparations decreased and increased, respectively. Kinetic studies showed that, after the osmolarity of the medium was changed, one protein was hardly incorporated into the membrane, whereas the other was incorporated with an increased rate. After about 1.5 to 2 generations, the cell envelopes obtained the b/c ratio characteristic for the new medium, and both proteins were subsequently incorporated in the cell ensured this new ratio. Once proteins b and c were incorporated in the cell envelope, they were not converted into each other by changes in osmolarity of the growth medium.

330 citations


Journal ArticleDOI
TL;DR: A methanogenic bacterium using H2 and CO2 as sole energy and carbon source has been isolated in pure culture from digested sludge and its colonies on mineral agar are translucent, convex, circular with entire margins and yellow to brownish in colour.
Abstract: A methanogenic bacterium using H2 and CO2 as sole energy and carbon source has been isolated in pure culture from digested sludge. Its colonies on mineral agar are translucent, convex, circular with entire margins and yellow to brownish in colour. Cells are gram-positive, non motile and appear as straight cods, normally about 3 μm long. A marked pleomorphism depending on the media was observed. The organism is chemolithoheterotrophic, has a pH optimum of 7.0 and an optimal temperature for growth of 33–40°C; no growth occurs above 45°C. The generation time at optimal conditions is less than 5 h. Cysteine must be supplied in the growth medium. It can act as sole sulfur source. The addition of sulfide accelerates the growth at an optimum concentration of 10-4 to 10-5 molar. A growth factor, not identical with SH-coenzyme M, occurring in anaerobic sewage sludge and yeast extract shows a stimulatory effect. 7.0–8.2% of the total carbon dioxide uptake is assimilated and 11.2% of the energy obtained from the reduction of carbon dioxide to methane is refound in the caloric value of the biomass. 0.01 ppm of dissolved oxygen completely inhibits growth and methane production. However, the bacteria do not loose their viability when exposed to high oxygen concentrations. Further informations are needed before this organism (DSM 744) is specifically identified.

202 citations


Journal ArticleDOI
TL;DR: Photoautotrophic growth in C. rubrum cell suspension cultures was correlated with the CO2 level and was enhanced by lowering the auxin concentration, and best growth was attained at 10−8M 2,4-D.
Abstract: A method is described for growing cell suspension cultures of Chenopodium rubrum photoautotrophically for prolonged periods of time. By using a two-tier culture vessel the growth medium with the cells was separated from the CO2 reservoir. Definite CO2 concentrations were established by a K2CO3/KHCO3 buffer. Photoautotrophic growth in C. rubrum cell suspension cultures was correlated with the CO2 level. At 0.5% CO2 the cell cultures contained 68 μg chlorophyll/g fresh weight and showed an increase in fresh weight of about 80% in 18 days. At 1% CO2 an increase in fresh weight of 165% in 18 days was observed. The chlorophyll content rose up to 84 μg/g fresh weight. The photoautotrophic growth was also greatly influenced by the 2,4-D content of the medium. Cell growth was enhanced by lowering the auxin concentration. Best growth was attained (210% increase in fresh weight) at 10−8M 2,4-D. The photosynthetic activity of the cells was measured by the light dependent 14CO2 incorporation. At 0.5% CO2 the cell suspensions assimilated about 100 μmol CO2/mg chlorophyll × h. In the presence of 1% CO2 the light driven assimilation was raised up to 185 μmol CO2/mg chlorophyll × h. In both cases, the dark incorporation of CO2 was merely 1.8% of the values obtained in light.

162 citations


Journal ArticleDOI
TL;DR: A method for testing organic chemicals for their carcinogenic potential is described and found to be more than 90% accurate in distinguishing between carcinogens and non-carcinogens.
Abstract: A method for testing organic chemicals for their carcinogenic potential is described Baby hamster kidney cells (BHK-21/C1 13) were exposed to different doses of test compound in liquid tissue culture medium containing rat liver post-mitochondrial supernatant and cofactors (S-9 mix) to aid metabolism, but without serum Survival of cells following exposure to the compound was assessed by cloning in liquid growth medium Transformation was assessed by colony growth in semi-solid agar The dose-response curve for survival was used to determine the LC50 of the compound A dose-response curve for transformation was constructed and a 5-fold increase in transformation frequency at the LC50 was regarded as a positive test result The method may also be used for testing gaseous compounds Cells grown in monolayers and overlaid with serum-free medium and S-9 mix were exposed to vinyl chloride gas mixed with air After exposure, the treated cells were trypsinized, resuspended in growth medium, and survival and transformation assays performed The methods described are illustrated by examples taken from an evaluation study using 120 compounds and found to be more than 90% accurate in distinguishing between carcinogens and non-carcinogens

112 citations


Journal ArticleDOI
TL;DR: The gluconeogenic requirement of a growing culture of E. coli was shown to be one-twentieth of its total catabolic and anabolic needs, which countered to a large extent the severe repression of beta-galactosidase synthesis that glucose caused in these mutants.
Abstract: Physiological properties of mutants of Escherichia coli defective in glyceraldehyde 3-phosphate dehydrogenase, glycerate 3-phosphate kinase, or enolase are described. Introduction of a lesion in any one of the reversible steps catalyzed by these enzymes impaired both the glycolytic and gluconeogenic capabilities of the cell and generated an obligatory requirement for a source of carbon above the block (gluconeogenic) and one below (oxidative). A mixture of glycerol and succinate supported the growth of these mutants. Mutants lacking glyceraldehyde 3-phosphate dehydrogenase and glycerate 3-phosphate kinase could grow also on glycerol and glyceric acid, and enolase mutants could grow on glycerate and succinate, whereas double mutants lacking the kinase and enolase required l-serine in addition to glycerol and succinate. Titration of cell yield with limiting amounts of glycerol with Casamino Acids in excess, or vice versa, showed the gluconeogenic requirement of a growing culture of E. coli to be one-twentieth of its total catabolic and anabolic needs. Sugars and their derivatives inhibited growth of these mutants on otherwise permissive media. The mutants accumulated glycolytic intermediates above the blocked enzyme on addition of glucose or glycerol to resting cultures. Glucose inhibited growth and induced lysis. These effects could be substantially overcome by increasing the osmotic strength of the growth medium and, in addition, including 5 mM cyclic adenosine 3',5'-monophosphate therein. This substance countered to a large extent the severe repression of beta-galactosidase synthesis that glucose caused in these mutants.

104 citations


Journal ArticleDOI
TL;DR: The synthesis of ribosomal ribonucleic acid (rRNA), transfer RNA (tRNA) and messenger RNA (mRNA) was measured in Escherichia coli B/r after the addition of 100 mug of chloramphenicol (CAM) to cultures growing either in one of three minimal media or in the same three media supplemented with 20 amino acids, suggesting a regulation of rRNA and tRNA synthesis at the transcriptional level.
Abstract: The synthesis of ribosomal ribonucleic acid (rRNA), transfer RNA (tRNA) and messenger RNA (mRNA) was measured in Escherichia coli B/r after the addition of 100 mug of chloramphenicol (CAM) per ml to cultures growing either in one of three minimal media (succinate, glycerol, or glucose) or in one of the same three media supplemented with 20 amino acids. (i) During CAM treatment, rRNA and tRNA were synthesized in the same relative proportions (85:15) as during exponential growth. The faster accumulation of tRNA relative to rRNA in CAM was due to a decreased stability of rRNA that is synthesized in the presence of or immediately before the addition of CAM. (ii) CAM stimulated the synthesis of rRNA and tRNA two- to eightfold. The results fell into two groups; one group was from studies done in minimal media and the other was from amino acid-supplemented media. In each group the stimulation decreased with increasing growth rate of the culture during exponential growth before the addition of CAM; however, the stimulation in minimal media was lower than that in amino acid-supplemented media. (iii) CAM caused an increase in the proportion of rRNA and tRNA synthesis and a corresponding decrease in the proportion of mRNA synthesis. In minimal media, the residual proportion of mRNA synthesis after CAM treatment was 10 to 15% of total RNA synthesis; in amino acid-supplemented media this proportion was 0 to 10%. In either case, the residual proportion of mRNA synthesis was independent of the proportions observed during exponential growth in these media. (iv) The absolute rate of mRNA synthesis decreased severalfold with the addition of CAM; i.e., the rate of synthesis of rRNA and tRNA was increased at the expense of mRNA synthesis. (v) During exponential growth, the fraction of the instantaneous rate of total RNA synthesis that corresponds to mRNA is a function of both the growth rate and the presence or absence of amino acids in the growth medium: in the absence of amino acids, this fraction decreased with increasing growth rate; in the presence of amino acids, the fraction increased slightly with growth rate. These results are consistent with a regulation of rRNA and tRNA synthesis at the transcriptional level, e.g., with a CAM-induced increase in the affinity of RNA polymerase for the rRNA and tRNA promoters. The results also suggest the occurrence of a regulation of RNA polymerase enzyme activity, i.e., of an activation of RNA polymerase that is inactive during exponential growth. A distinction between these alternatives requires measurements of the rRNA chain growth rates during CAM treatment.

61 citations


Journal ArticleDOI
TL;DR: In WI-38, a normal human fibroblast, the rates of degradation of short lived and long lived proteins are identical whether the cultures are growing exponentially or are density-inhibited and the rate of degradation is closely coupled to certain medium alterations.

52 citations


Journal ArticleDOI
TL;DR: The fatty acid composition of lactic acid bacteria, inhibited by the antibiotic cerulenin, can be modulated by exogenously added oleic acid (or Tween 80) without the concurrent endogenous fatty acid synthesis from acetate.
Abstract: The viability of Streptococcus lactis and Lactobacillus sp. A-12 after freezing at -17°C for 48 h was better preserved when the cells were grown in medium supplemented with oleic acid or Tween 80 (polyoxyethylene sorbitan monooleate). A pronounced change in the cellular fatty acid composition was noted when the bacteria were grown in the presence of Tween 80. In S. lactis the ratio of unsaturated to saturated fatty acids increased from 1.18 to 2.55 and in Lactobacillus sp. A-12 it increased from 0.85 to 1.67 when Tween 80 was added to the growth medium. The antibiotic cerulenin markedly inhibited the growth of lactic acid bacteria in tomato juice (TJ) medium but had almost no effect on the growth of the bacteria in TJ medium containing Tween 80 (or oleic acid). The antibiotic inhibited markedly the incorporation of [1-14C]acetate but had no inhibitory effect on the incorporation of exogenous [1-14C]oleate (or [1-14C]palmitate) into the lipid fractions of lactic acid bacteria. Thus, the fatty acid composition of lactic acid bacteria, inhibited by the antibiotic cerulenin, can be modulated by exogenously added oleic acid (or Tween 80) without the concurrent endogenous fatty acid synthesis from acetate. The data obtained suggest that cerulenin inhibits neither cyclopropane fatty acid synthesis nor elongation of fatty acid acyl intermediates. The radioactivity of cells grown in the presence of [1-14C]oleate and cerulenin was associated mainly with cyclopropane Δ19:0, 20:0 + 20:1, and 21:0 acids. As a consequence, cerulenin caused a decrease in the ratio of unsaturated to saturated fatty acids in lactic acid bacteria as compared with cells grown in TJ medium plus Tween 80 but without cerulenin. Cerulenin caused a decrease in the viability of S. lactis and Lactobacillus sp. A-12 after freezing at -17°C for 48 h only when Tween 80 was present in the growth medium. We conclude that the sensitivity of lactic acid bacteria to damage from freezing can be correlated with specific alterations in the cellular fatty acids.

52 citations


Journal ArticleDOI
TL;DR: Leucine proved to be a desirable marker for protein turnover studies due to its minimal metabolism when labeling was performed in growth medium and the appearance of radioactive leucine in the medium of cells previously labeled with [14C]leucine was shown to be directly correlated with loss of radioactivity in cellular protein.

40 citations


Journal ArticleDOI
01 Aug 1977-Diabetes
TL;DR: The present results strongly suggest that the increased stimulatory effect of normolipemic human diabetic serum on growth and cell proliferation of aortic medial cell cultures is due to increased serum growth hormone concentration.
Abstract: Growth medium containing serum from young diabetic subjects caused a significant stimulation both of cell proliferation and of the outgrowth in cultures of rabbit aortic medial cells above that noted with normal human sera. The addition to the sera of guinea-pig human growth hormones antibody caused a marked inhibition of these stimulatory effects. The growth effect of rabbit serum was not affected by the human growth hormone antiserum. Reinvestigation of the effect of human growth hormone disclosed that the same increase as observed in growth with the diabetic sera could be obtained with a growth hormone concentration of 0.2 ng. per milliliter medium. The present results strongly suggest that the increased stimulatory effect of normolipemic human diabetic serum on growth and cell proliferation of aortic medial cell cultures is due to increased serum growth hormone concentration.

Journal ArticleDOI
TL;DR: The formation of the bisphosphatidic acids may be specifically linked to the autolysis of the phospholipids of the cellular membranes and the formation of triglycerides associated with this process.

Journal ArticleDOI
TL;DR: The addition of both urea and putrescine to the growth medium and incubation in a humidified CO2 atmosphere are recommended for improved growth and formation of fried-egg colonies of U. ureaplyticum on agar.
Abstract: The morphology of Ureaplasm urealyticum in broth cultures was studied by phase-contrast microscopy. Most organisms appeared singly or in pairs. Long filaments and long chains of cocci, common in classical mycoplasma cultures, were not observed. On solid medium, U. urealyticum produced "fried-egg" colonies which developed according to the scheme suggested by Razin and Oliver (J. Gen. Microbiol., 1961) for the morphogenesis of the classical mycoplasma colonies. The formation of the peripheral zone of the colonies followed that of the central zone only when growth conditions were adequate, Hence, the appearance of peripheral zones, and consequently the larger colony size, can be taken as an indicator of improved growth conditions. Incubation in an atmosphere of 100% CO2 resulted in significantly larger colonies than in an atmosphere of N2, O2, or air. CO2 acts as a buffer, keeping the pH at the optimal range for Ureaplasma growth (pH 6.0 to 6.5) in the presence of the ammonia produced from the urea hydrolyzed by the organisms. The addition to the medium of 0.01 M urea together with 0.01 M putrescine enabled better growth than with urea alone. Small amounts of phosphate improved growth in an atmosphere of CO2, apparently fulfilling a nutritional role. Under nitrogen, higher phosphate concentrations were required for good growth, apparently serving as a buffer as well as a nutrient. Sodium chloride and sucrose which had been added to increase the tonicity of the medium inhibited growth above 0.1 M. An increase in the agar concentration above 2% resulted in decreased colony size. Likewise, prolonged drying of the agar plates caused a marked decrease in colony size, mostly affecting the peripheral zone. The addition of both urea and putrescine to the growth medium and incubation in a humidified CO2 atmosphere are recommended for improved growth and formation of fried-egg colonies of U. ureaplyticum on agar. It must be emphasized that these experiments were carried out with a laboratory-adapted strain.

Journal ArticleDOI
TL;DR: The data strongly suggest that the mitochondrial protein-synthesis system is required for the normal function of the inorganic phosphate-carrier activity of Saccharomyces cerevisiae mitochondria.

Journal ArticleDOI
TL;DR: The rate of accumulation of ammonium ion in cultures of Ureaplasma urealyticum was independent of the growth rate and of the initial urea concentration above 0-025% in the medium, although the quantity of ammonia ion accumulating did depend on the initialUrea concentration.
Abstract: SUMMARY: The rate of accumulation of ammonium ion in cultures of Ureaplasma urealyti-cum was independent of the growth rate and of the initial urea concentration above 0.025% in the medium, although the quantity of ammonium ion accumulating did depend on the initial urea concentration. Ammonium ions accumulated at a similar rate in U. urealyticum cultures of both rapidly and slowly growing organisms. Viable but non-growing ureaplasmas also produced ammonia in complete medium at a lower temperature than usual (25°) or in an inadequate growth medium at 37 °. The rate of ammonium ion accumulation in a dying culture depended on the number of viable organisms present; this is relevant to diagnostic methods for ureaplasmas which depend on detecting ammonia colorimetrically.

Journal ArticleDOI
TL;DR: Evidence was obtained that the protozoa obtained the amino acids required for growth largely from engulfed bacteria, and there was no appreciable synthesis of protozoal protein from carbohydrate.
Abstract: Entodinium longinucleatum grown in vitro in the presence of bacteria engulfed a wide range of bacterial species at rates of 130–3400 bacteria/h/protozoon (from suspensions of 10 bacteria/ml), but showed a preference for Klebsiella aerogenes and Proteus mirabilis which occurred in the growth medium. Some of the bacteria were digested with release of soluble material into the medium. Free amino acids were incorporated by the protozoa in the presence of chloramphenicol at rates of 5·4–15·1 nmol/h/106 protozoa and approximately 40% of the amino acid-carbon was incorporated into protein. There was no appreciable synthesis of protozoal protein from carbohydrate. Evidence was obtained that the protozoa obtained the amino acids required for growth largely from engulfed bacteria.

Journal ArticleDOI
TL;DR: It is concluded that transit through G2 requires the presence of an extracellular factor, and Vero cells cannot pass through a transition point in G2.
Abstract: When Vero cells, a line derived from and African Green Monkey kidney, are grown under conditions where the saturation density is limited by serum, they deplete the growth medium of a factor necessary for cell division. The factor is a component of serum. When Vero cells are plated at low density (2 X 10(4)/cm2) in this depleted growth medium (after dialysis against serum-free Dulbecco's Modified Eagle's Medium) they initiate an unbalanced program of growth. Protein synthesis proceeds at the same rate as parallel cells in fresh serum, and and the cells accumulate protein as a function of time. DNA synthesis is also initiated in these cells, and the amount of DNA per cell increases for the next four days plating. However the cells quickly stop dividing. Measurements of DNA per cell using microspectrofluorometry show that the cells are accumulating in the late S and G2 period during this time. Thus we conclude that these cells cannot pass through a transition point in G2. When fresh serum is added to cells after three days in depleted growth medium, they divide before they begin to synthesize DNA. This further confirms that they are in late S and G2. Cell division is promoted in Vero cells in depleted growth medium by bovine fetuin, and to a lesser extent by bovine albumin. Cell division is not promoted by insulin, hydrocortisone, dexamethasone, linolenic acid, calcium, and typsin inhibitor form ovomucoid. From these data we conclude that transit through G2 requires the prescence of an extracellular factor.

Journal ArticleDOI
TL;DR: The multiplication of Vero cells in vitro as measured by population doubling time and final saturation density is regulated by the serum concentration in the medium and not by the substratum area available for cell growth, consistent with the model that the growth of most cultured cells is controlled by medium components especially serum growth factors.

Journal ArticleDOI
01 Jan 1977-Planta
TL;DR: It is argued that the biological significance of the increased protein degradation does not lie in its contribution to respiration but as a mechanism to replace one set of enzyme adapted to a particular environmental condition (high nitrogen) with another set of enzymes adapted for low nitrogen in the environment.
Abstract: When Lemna is deprived of nitrogen, growth and respiration decrease and the pattern of 14CO2 release from [1-14C]glucose and [6-14C]glucose is consistent with a relatively strong inhibition of glycolysis. Protein degradation is enhanced but the concentration of free amino acid decreases. It is argued that the biological significance of the increased protein degradation does not lie in its contribution to respiration but as a mechanism to replace one set of enzymes adapted to a particular environmental condition (high nitrogen) with another set of enzymes adapted for low nitrogen in the environment. The change in enzyme pattern associated with the change from high to zero nitrogen in the growth medium has been examined for nine enzymes. The changes in activity observed are consistent with the observed apparent inhibition of glycolysis during nitrogen starvation, but do not explain the inhibition of the pentose phosphate pathway.

Journal Article
TL;DR: The time of appearance and degree of cytopathic effect, plaque-forming ability, and propagation of some avian viruses were similar in both cultures prepared in medium with or without serum.
Abstract: When chicken kidney cell (CKC) culture in a petri dish was prepared in medium with or without serum and incubated in a humidified incubator at 38 degreesC with no addition of CO2, monolayers of CKCs were formed completely on the 5th day of cultivation Growth medium used for CKC culture was Eagle's minimum essential medium containing 03% of dehydrated tryptose phosphate broth The number of cells in both cultures prepared in medium with or without serum was the same when measured on the 5th day of cultivation Monolayers of CKC culture prepared in medium with or without serum were maintained up to 21 days of cultivation, while maintenance medium was changed every 4th day The time of appearance and degree of cytopathic effect, plaque-forming ability, and propagation of some avian viruses were similar in both cultures prepared in medium with or without serum

Journal ArticleDOI
TL;DR: Aggregate properties (size, viability, and proliferation) of transformed cells correlated with growth in soft agar and tumorigenicity, and when transplanted into newborn rats, the transformed cells produced sarcomas.
Abstract: We studied the transformation of epithelial, diploid cell lines (RL-33 and RL-34) derived from W rat liver by the Kirsten murine sarcoma virus. On days 4-5 after virus infection, the epithelial cells began to pile up focally, forming small projections and releasing round cells from the foci. The epithelial cells grew in chains or as islets and grew in suspension above the cells attached to the bottom of the flasks when the cultures reached the confluent stage. The virus titration pattern was "one-hit." Three classes of transformed cells were isolated with respect to virus release and antigen expression: 1) virus producer, 2) non-producer, and 3) sarcoma-positive, leukemia-negative cells. When transplanted sc into newborn rats, the transformed cells produced sarcomas. The transformed cells formed within 1-3 days larger aggregates than those of their normal counterpart cells when suspended in liquid growth medium above an agar base. Aggregate properties (size, viability, and proliferation) of transformed cells correlated with growth in soft agar and tumorigenicity. RNA-dependent DNA polymerase and type C virus particles were readily induced in the normal rat liver epithelial cells after exposure to 5-iodo-2'-deoxyuridine.

Journal ArticleDOI
TL;DR: The results from these studies indicate possible differences in sugar uptake and/or utilization in Lemna perpusilla.
Abstract: Lemna perpusilla Torr, strain 6746 clones were maintained under conditions of continuous illumination with various concentrations of sucrose, glucose or fructose added to the growth, medium. After two weeks of growth, plants were harvested and either assayed for total glutamate dehydrogenase activity or fractionated into one chloroplast-rich and one mitochondria-rich preparation and then assayed for glutamate dehydrogenase activity. In all assays for glutamate dehydrogenase it was necessary to add bovine serum albumin to the extraction medium in order to obtain sufficient enzyme activity for accurate and reproducible results. The presence of sucrose in the growth medium reduced glutamate dehydrogenase activity in all studies. When samples containing intact organelles were assayed, sucrose inhibition of activity appeared to occur primarily in the chloroplast fraction. Glucose, on the other hand, increased glutamate dehydrogenase activity in the chloroplast-rich fractions. Upon freeze-thawing differences between the various treatments were less obvious. The results from these studies indicate possible differences in sugar uptake and/or utilization in Lemna perpusilla.

Journal ArticleDOI
TL;DR: Results indicate that CS from batch, semi-continuous and continuous cultures could be utilized as growth medium following the addition of lactalbumin hydrolysate (LH), tryptose phosphate broth (TPB), glucose, glutamine and 1% serum.

Journal ArticleDOI
01 Mar 1977
TL;DR: Two methods for the controlled formation of protoplasts of the yeastKloeckera sp.
Abstract: Two methods for the controlled formation of protoplasts of the yeastKloeckera sp. 2201 grown on methanol as sole carbon source are presented. For the lysis of yeast cell walls, an extracellular enzyme, produced byArtbrobacter luteus and called Zymolyase-5000, is used. The carbon source of the growth medium greatly influences the susceptibility of the yeast cell wall against the attack of this enzyme. Glucose-grown cells can easily be converted into protoplasts without preceding incubation with β-mercaptoethanol, whereas cells grown on methanol require preincubation. A 20–30% decrease of O.D.650 indicates complete formation of protoplasts. A further decrease of O.D. is the result of partial bursting of the protoplasts. The formation of protoplasts in isotonic media starts with the formation of holes in the yeast cell wall. This enzymatic perforation is then followed by the release of the protoplasts.

Journal ArticleDOI
TL;DR: It was concluded that possible sites for coremia develop intoPrimordia as a result of changes in nitrogen metabolism, and that local variations in the concentrations of certain amino acids or their metabolites may decide the pattern in which primordia form in the colony.
Abstract: Summary: Amino acids added to the growth medium stimulated development of coremium primordia in mycelium of Penicillium claviforme. Casein hydrolysate, l-asparagine, l-serine, l-glutamine, l-proline, l-hydroxyproline, l-glutamate and glycine accelerated development and also increased the final number of primordia per unit area of mycelium. A nearly linear relationship existed between the logarithm of casein hydrolysate concentration and the numbers of primordia developed, and a similar relationship was also shown with glutamate as nitrogen source. Mycelium developing from spores sown on agar plates showed some sites for coremium development within a few hours of germination, although most sites were not established until about 24 h later when the germlings had fused to form a network. At least 27 h exposure was required for amino acids to stimulate primordium development in 24 h-old mycelium. Cycloheximide, glucosamine and nystatin promoted primordium development at concentrations inhibiting hyphal growth; 2-deoxyglucose inhibited primordium formation. It was concluded that possible sites for coremia develop into primordia as a result of changes in nitrogen metabolism, and that local variations in the concentrations of certain amino acids or their metabolites may decide the pattern in which primordia form in the colony.

Journal ArticleDOI
Daphne Kamely1
TL;DR: The present results suggest that insulin‐stimulated growth is mediated by a different pathway than serum‐ Stimulated growth and is sensitive to mechanisms that occur at various times prior to insulin addition.
Abstract: Cultured mouse and human cells were arrested in their growth by artificially depriving them of phosphate The quiescent cells could be stimulated to synthesize DNA and to divide by addition to the growth medium of insulin, dialyzed serum and/or the full concentration of phosphate In order to gain insight into mechanisms by which insulin and serum stimulate growth, the inhibitory effects of antimitotic agents were examined Of the inhibitors tested, vinblastine and cytocalasin B abolished the growth promoting activity of insulin, while colchicine inhibited the activity of both serum and insulin The present results suggest that insulin-stimulated growth is meciated by a different path way than serum-stimulated growth and is sensitive to mechanisms that occur at various times prior to insulin addition

Patent
11 Aug 1977
TL;DR: In this article, a semi-solid filter cake waste product from potato processing is used as a growth medium for producing single-cell protein, and a pre-fermenting yeast, such as Endomycopsis fibuliger, is introduced into the growth medium to produce amylase for breaking down into glucose the starch naturally present in the potato waste medium.
Abstract: A semi-solid filter cake waste product from potato processing is used as a growth medium for producing single-cell protein. A pre-fermenting yeast, such as Endomycopsis fibuliger, is introduced into the growth medium to produce amylase for breaking down into glucose the starch naturally present in the potato waste medium. A primary fermenting yeast, such as Candida utilis, is introduced to the potato waste medium and uses the glucose for growth.

Journal ArticleDOI
TL;DR: Thermally injured cells of Pseudomonas fluorescens were unable to produce colonies on Trypticase soy agar after dilution with 0.1% peptone, demonstrating that the heat treatment sensitized the cells to the trauma of dilution.
Abstract: Thermally injured cells of Pseudomonas fluorescens were unable to produce colonies on Trypticase soy agar (TSA) after dilution with 0.1% peptone. Nutritional exigency could not be used as the criterion for this injury, since varying the composition of the plating medium had little effect on the number of colonies that developed. The injured cells had no requirement for compounds known to leak out during the heat treatment in order to recover. The cells did not exhibit injury if dilution preceded heat treatment on the plating medium, demonstrating that the heat treatment sensitized the cells to the trauma of dilution. Substitution of 0.1% peptone with growth medium as the diluent largely offset the previously observed drop in TSA count. Little difference in survival was observed when monosodium glutamate or the balance of the defined medium was used as the diluent. The diluent effect was ionic rather than osmotic. The presence of cations was important in maintaining the integrity of the injured cell, and divalent cations enhanced this protective effect. The role of these cations at the level of the cell envelope is discussed.

Journal ArticleDOI
TL;DR: Adding Tween 80 to the growth medium of baker's yeast under anaerobic conditions resulted in an increased content of 9-cis-octadecenoic acid (oleic acid) in a membrane preparation consisting mainly of plasma membrane, presumably because of an oleate-induced increase in the permeability of the plasma membrane to pyruvate.
Abstract: Addition of Tween 80 to the growth medium of baker's yeast (Saccharomyces cerevisiae) under anaerobic conditions resulted in an increased content of 9-cis-octadecenoic acid (oleic acid) in a membrane preparation consisting mainly of plasma membrane. There was no significant effect on the pyruvate decarboxylation capacity of disintegrated cells, but that of intact cells was significantly enhanced, presumably because of an oleate-induced increase in the permeability of the plasma membrane to pyruvate.

Journal ArticleDOI
TL;DR: A growth medium with a specific oxidation-reduction potential containing peptone, dextrose, sodium succinate, sodium lactate, gelatin, sodium bicarbonate and blue tetrazolium in a tris(hydroxymethyl)aminomethane buffer was used to detect the presence of microorganisms in blood.
Abstract: A growth medium with a specific oxidation-reduction potential containing peptone, dextrose, sodium succinate, sodium lactate, gelatin, sodium bicarbonate and blue tetrazolium, an indicator dye, in a tris(hydroxymethyl)aminomethane buffer was used to detect the presence of microorganisms in blood. The procedure involved the introduction of blood (and bacteria) into the growth medium with the dye in its colorless state. As the bacteria grew, they converted the dye to a visible blue color (formazan) with their reductases. The growth medium served as its own contamination control, since microbial growth and be detected by a color change before it was used for blood culture. The experiments described herein demonstrate that the composition of this medium (with the dye) provides a unique system that is able to make a reliable and rapid detection of both gram-positive and gram-negative microorganisms and yeasts (Candida albicans) commonly associated with bacteremia.