J Cell Sci, 1977 Jun, 25, 95 - 102 Preferential inhibition of rDNA transcription by 5-bromodeoxyuridine; Lykkesfeldt AE et al.; On a chemically defined growth medium the degree of substitution of thymidine with 5-bromodeoxyuridine (BUdR) in DNA of Tetrahymena pyriformis was controlled by the concentration of tetrahydrofiolic acid, BUdR and thymidine in the medium . A correlation between the degree of BUdR substitution in DNA and the reduction in rate of total RNA synthesis has been established . It was found that the reduction of total RNA synthesis results from inhibition of transcription of all RNA species which have been measured . However, independent of the degree of BUdR substitution in DNA, a preferential inhibition of the synthesis of 25s and 17s ribosomal RNA was found . It is concluded that the various genes may respond differently to BUdR substitution with respect to transcription. Int J Radiat Biol Relat Stud Phys Chem Med, 1977 Jun, 31(6), 507 - 18 Influence of a uvrD mutation on survival and repair of X-irradiated Escherichia coli K-12 cells; van der Schueren E et al.; The presence of a uvrD mutation increased the X-ray sensitivities of E . coli wild-type and polA strains, but had no effect on the sensitivities of recA and recB strains, and little effect on a lexA strain . Incubation of irradiated cells in medium containing 2,4-dinitrophenol or chloramphenicol decreased the survival of wild-type and uvrD cells, but had no effect on the survival of recA, recB and lexA strains . Alkaline sucrose gradient sedimentation studies indicated that the uvrD strain is deficient in the growth-medium-dependent (Type III) repair of DNA single-strand breaks . These results indicate that the uvrD mutation inhibits certain rec+lex+-dependent repair processes, including the growth-medium-dependent (Type III) repair of X-ray-induced DNA single-strand breaks, but does not inhibit other rec+lex+-dependent processes that are sensitive to 2,4-dinitrophenol and chloramphenicol. Genetics, 1977 Jun, 86(2 Pt . 1), 399 - 411 The effects of genotype frequency and population density on fitness differentials in Escherichia coli; Smouse P et al.; Two strains of Escherichia coli K-12, a lac+ wild type and a lac- auxotroph, were grown both as pure and mixed cultures, using a serial transfer procedure . Four different growth media were employed, consisting of the same minimal salts solution, but different total concentrations of the sugars lactose, arabinose, and glucose (in proportions 5:4:1) . Population densities and genotypic frequencies were assayed every 48 hours, at the time of transfer . Population density of the pure lac+ culture was greater than that of the pure lac- culture for all media; this was expected, since the latter cannot utilize lactose . Mixed cultures quickly approached the same density as the corresponding lac+ controls, and the frequency of the lac+ genotype increased steadily for all media . Trajectories of lambda = log (P divided by Q) were strictly nonlinear, indicating a dependence of the selective differential on population density and genotypic frequency . The rate of substitution decreased slightly with increasing sugar concentration, contrary to theoretical expectation . It was speculated that either the generation interval was longer for denser cultures (higher substrate concentrations) of that buildup of organic by-products reduced the selective differential in denser cultures . For a single medium, however, the behavior of completing genotypic strains was reasonably well predicted by theoretical models of frequency and density-dependent selection, the parameters of which may be related to the experimental inputs. Can J Microbiol, 1977 Jun, 23(6), 690 - 4 Induction of multispored asci in two-spored strains of Saccharomyces cerevisiae by amitrole; Ashraf M et al.; Although growth of two yeast strains characterized by consistent production of two diploid spores per ascus was inhibited in complex presporulation media containing amitrole, a fraction of the cells produced were able to form asci with more than two spores after transfer to acetate sporulation medium . Cells grown in a defined presporulation medium containing amitrole did not acquire this ability . The increase in spore numbers per ascus is attributed either to the induction by amitrole in growth medium of cells with more than one nucleus or to the restoration of normal meioses in the multispored asci. Jpn J Med Sci Biol, 1977 Jun, 30(3), 125 - 35 Studies on the respiratory system of Aspergillus oryzae . V . Some properties of the respiratory system of mitochondria from mycelia grown in the presence of chloramphenicol; Saito-Wakiyama S et al.; Presence of chloramphenicol in the growth medium for mycelia of Aspergillus oryzae was without effect on the oxidative activity, respiratory control, or P/O ratio of isolated mitochondria . The mitochondria oxidized Krebs cycle intermediates even in the presence of cyanide at the concentration markedly inhibiting the normal mitochondrial oxidation . However, the P/O ratio during the mitochondrial oxidation decreased by about 1.0 on addition of cyanide . The c-type cytochromes, shown to occur in large amounts than in normal mitochondria (Wakiyama and Ogura, 1972), were suggested to act as electron carriers in this cyanide-resistant oxidation . A novel pigment, demonstrated only in the mitochondria prepared from chloramphenicol-treated mycelia by a CO-difference spectrum, was presumed to be the terminal oxidase of the respiration in the presence of cyanide. J Biol Chem, 1977 May 25, 252(10), 3272 - 6 Induction of 3-hydroxy-3-methylglutaryl coenzyme A reductase in HeLa cells by glucocorticoids; Cavenee WK et al.; The activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase, EC 1.1.1.34) has been demonstrated both in homogenates and microsomes of the S3G strain of HeLa cells . It was increased 8- to 10-fold by the removal of serum from the growth medium . The presence of steroids, specifically of the glucocorticoid series, in the serum-less growth medium elicited an additional 100 to 345% increase over the serum-less control, whereas the addition of N6,O2'-dibutyryl adenosine 3':5'-monophosphate to the medium or dexamethasone to the assay mixture was without any stimulatory effect . Both inductions were blocked by cycloheximide and actinomycin D, suggesting a protein synthesis-dependent elevation of enzyme activity . Glucocorticoids were effective in the induction at concentrations ranging from 10(-6) to 10(-8) M and there was a demonstrated parallel between the magnitude of enzyme induction and glucocorticoid potency . The HMG-CoA reductase activities from steroid-induced and control cultures had identical assay characteristics (pH optima and apparent Km values for both NADPH and HMG-CoA) . This induction of the rate-controlling enzyme of cholesterogenesis occurred despite the observation that glucocorticoids specifically depress the rate of acetate or water, but not mevalonate, incorporation into cholesterol. Biochemistry, 1977 May 3, 16(9), 1881 - 90 Use of a fluorescent probe to determine the viscosity of LM cell membranes with altered phospholipid compositions; Esko JD et al.; The phospholipid compostition of LM cells grown in tissue culture was altered by substituting ethanolamine for choline in the growth medium . The plasma membrane isolated from cells grown in medium conatining ethanolamine for 83 h had a sixfold increase in the ratio of phosphatidylethanolamine to phosphatidylcholine, the two major phospholipid classes . This was accompanied by small changes in other lipid components of the membrane . There was also a sixfold increase in the amount of triacylglycerols and alkyldiacylglycerols which were not associated with the membrane fraction of the cell . No significant changes occurred in the lipid composition of cells during growth in choline containing medium . The viscosity of plasma membranes was studied in whole cells and isolated membranes using the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene . Plasma membranes isolated from ethanolamine-supplemented cells had greater viscosities than membranes isolated from choline-supplemented cells . When whole cells were labeled with the fluorescent probe, the opposite trend in the apparent membrane viscosity was observed . This was due primarily to the probe penetrating into nonmembranous neutral lipids rather than remaining localized in the surface membrane of the cells . Since the enthanolamine-supplemented cells contained more low viscosity neutral lipids, the whole cells gave an apparently lower viscosity as compared with choline-supplemented cells, thus, measurements carried out on whole cells gave an inaccurate determination of the viscosity of the surface membrane. Biochemistry, 1977 May 3, 16(9), 1871 - 5 Synthesis and uptake of gangliosides by choleragen-responsive human fibroblasts; Fishman PH et al.; Human fibroblasts, cultured in medium containing 10% fetal calf serum, responded dramatically to choleragen with an increase in cyclic adenosine monophosphate content to greater than 48 times basal levels . Analysis of these cells for gangliosides indicated that the major ganglioside was N-acetylneuraminylgalactosylglucosylceramide (GM3) with trace amounts (less than or equal to 100 pmol/mg of protein) of other gangliosides including GM1, the putative choleragen receptor . Although the cells contained three glycosyltransferases required for ganglioside synthesis, the N-acetylgalactosaminyltransferase activity necessary for the conversion of GM3 to more complex gangliosides was not detected . When the cells were grown in medium containing {14C}galactose or N-acety{3H}mannosamine, however, all of the gangliosides became labeled, indicating that the cells can synthesize complex gangliosides . Although fetal calf serum contains gangliosides including GM1, {3H}GM1 was taken up poorly from the growth medium and uptake at the rate observed could have accounted for less than 2% of the GM1 content of the cells . When the cells were incubated in chemically defined medium containing {3H}GM1 at the concentrations present in fetal calf serum, rapid uptake of the ganglioside occurred and the total GM1 content of the cells increased threefold in less than 3 h . Thus, although the cells are capable of binding exogenous gangliosides, the gangliosides in fetal calf serum are in a form not readily available to the cells. Mikrobiologiia, 1977 May-Jun, 46(3), 529 - 38 {Comparative cytomorphologic study of strains of Aspergillus terricola in the process of biosynthesis of proteolytic enzymes}; Usenko LI et al.; The cytology and morphology of three strains of Aspergillus terricola were studied in the course of synthesis of proteolytic enzymes . The level of the enzymes in the cultural broth was highest during the growth of the diffused mycelium, and was accompanied with specific cytodifferentiation of the fungal hyphae . The contact between the hyphae of the producing culture and the growth medium is presumed to be important for biosynthesis of the enzymes. J Lipid Res, 1977 May, 18(3), 379 - 88 Experimentally caused proliferation of lysosomes in cultured BHK cells involving an increase of biphosphatidic acids and triglycerides; Brotherus J et al.; When cultured hamster fibroblasts (BHK 21 cells) were incubated in a synthetic serum-free medium up to 4 days, they developed signs of a progressive proliferation of lysosomes . The cells became filled with vacuoles that contained polymorphic debris and showed acid phosphatase activity . The specific activities of acid protease and acid phosphatase in the cell cultures increased three- to fourfold . The process was accompanied by a marked decrease in the contents of protein, deoxyribonucleic acid, and total phospholipids of the cultures . The concentration of lysobisphosphatidic acid increased during the incubation from about 1.5% to 3-6% of the cellular phospholipids . The concentrations of two related lipids, bisphosphatidic acid and semilysobisphosphatidic acid also increased substantially . The triglyceride content of the cells increased several fold, whereas the concentration of phosphatidylcholine decreased markedly . Lysobisphosphatidic acid did not increase upon induction of vacuolization by exogenous sucrose, nor when there was an accumulation of triglyceride due to addition of oleic acid to the growth medium . These findings suggest that 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. Somatic Cell Genet, 1977 May, 3(3), 263 - 80 Increased intracellular phosphoribosylpyrophosphate and accelerated orotic acid decarboxylation in a mouse cell line resistant to purine and pyrimidine ribonucleosides; May SR et al.; A line of mouse fibroblasts (A9AU-1), originally selected for growth in the presence of 6-azauridine, has been found to be resistant to cytotoxic concentrations of adenosine, guanosine, and thymidine . A9AU-1 cells convert orotic acid to uridine 5'-monophosphate at twice the rate of the A9P line from which the A9AU-1 clone was selected . The resistant cells also excrete purines, synthesized de novo, into the medium at an increased velocity . The average intracellular 5-phosphoribosyl-1-pyrophosphate (PRPP) concentration of the resistant line is 45% higher than that of the parental line . The elevated PRPP concentration is likely to be responsible for both the apparent acceleration of pyrimidine synthesis and the increased excretion of purines into the growth medium; it might also account, by one of the several possible mechanisms, for the resistance of the cells to cytotoxic concentrations of the various nucleosides. J Protozool, 1977 May, 24(2), 275 - 83 Effects of dimethyl sulfoxide on Tetrahymena pyriformis GL . Fine structural changes and their reversibility; Nilsson JR; Fine-structural changes are induced in Tetrahymena by exposure to 7.5% dimethyl sulfoxide (DMSO) in the presence of growth medium . Some of these changes (nucleolar, mitochondrial, peroxisomal) resemble those seen during starvation, in agreement with the previously reported inhibitory effect of DMSO on food-vacuole formation; however, changes such as helical formations of polyribosomes indicate additional internal actions of the reagent . The effects vary to some extent within the same group of cells, suggesting that sensitivity to the reagent may differ with the stage in the cell cycle . The structural changes induced by a 1-hr exposure to DMSO are reversible, but recovery of the cells after removal of the reagent is slower than that seen after starvation . The observations suggest that the recovery is associated with renewed synthesis. Mikrobiologiia, 1977 May-Jun, 46(3), 433 - 9 {Mechanism of action of glucose on L-asparaginase synthesis by Escherichia coli bacteria}; Garaev MM et al.; The synthesis of L-asparaginase in Escherichia coli W and E . coli K-12 was almost completely supressed if glucose was added at a concentration of 0.5 per cent to a growth medium . The level of L-asparaginase synthesis decreased by ca . 75 per cent as a result of cyamutations when the bacteria could not produce cyclo-3',5'-AMP (cAMP) . Apparently, a decrease in the intracellular content of cAMP caused by glucose could not be the only factor inhibiting L-asparaginase synthesis . Lactate was found to stimulate L-asparaginase synthesis . Glucose caused the catabolite repression and catabolite inhibition of the components of a system involved in lactate transport . The inhibition of L-asparaginase synthesis by glucose seems to be due, at least partly, to the fact that it prevents the assimilation of lactate by the cells, as well as the utilization of some other compounds which stimulate synthesis of this enzyme. J Natl Cancer Inst, 1977 May, 58(5), 1515 - 8 Expression of Mason-Pfizer and simian type C viruses in the presence of 5-iododeoxyuridine and dexamethasone; Ahmed M et al.; Production of infectious Mason-Pfizer monkey virus (M-PMV) was enhanced after treatment of the CMMT cell line with 2.5 x 10(-5) M dexamethasone phosphate (DXM) . The reverse transcriptase (RT) activity and infectivity titers of treated culture fluids were enhanced by five- and tenfold, respectively . Along with stimulation of M-PMV synthesis, a simian type C virus (SCV) was also detected by electron microscopic and RT analyses . The SCV was serologically related to the endogenous baboon type C virus . 5-iododeoxyuridine (IUDR) also activated the SCV in the CMMT cell line while significantly inhibiting the production of infectious M-PMV . The activation of endogenous SCV by IUDR or DXM was transitory, since removal of these compounds from the growth medium resulted in the disappearance of SCV buds and the related RT activity; however, low levels of specific viral structural proteins continued to be synthesized intracellularly . Similarly, the enhancement of M-PMV production seen with DXM was lost when the treated cells were subcultured for 2 weeks in the absence of the hormone. Biochim Biophys Acta, 1977 Apr 18, 466(2), 336 - 46 Qualitative and quantitative variations of membrane lipid species in Acholeplasma laidlawii A; Wieslander A et al.; In Acholeplasma laidlawii A, strain EF 22, the relative amounts of the membrane polar lipids vary as a consequence of different fatty acid supplements to the growth medium . The number of lipid species also varies; a new apolar monoglucolipid containing four fatty acid residues was present only when saturated fatty acids dominated in the growth medium . A new phosphoglucolipid, probably with a glycerophosphoryl-monoglucosyldiglyceride structure, was also found . The most pronounced variations occurred between the two dominating glucolipids, monoglucosyldiglyceride and diglucosyldiglyceride; the former being found in larger amounts when a saturated or a trans-unsaturated fatty acid was present in the medium . The amount of diglucosyldiglyceride decreased accordingly . A qualitative relationship between fatty acid properties and membrane lipid variations was established over a wide fatty acid concentration range . Incorporation of supplied fatty acids reached higher levels than normally found in other acholeplasmas . The ratio between membrane protein and lipids exhibited significant and coherent variations during growth and was to some extent influenced by the fatty acids in the medium . These changes indicate variations in lipid-protein organization in the membranes during growth. Aust J Biol Sci, 1977 Apr, 30(1-2), 21 - 31 Dithionite reduction in the presence of a tetrapyrrole-containing fraction from the desulfoviridin of Desulfovibrio gigas; Skyring GW et al.; Low-molecular-weight fractions obtained from the desulfoviridin of D . gigas and from the growth medium of Desulfovibrio sp . 10455 promoted the reduction of sodium dithionite to sulphide in the presence of reduced methylviologen . These fractions contained a tetrapyrrole of the isobacteriochlorin type which was not complexed with iron, nor was it complexed with protein . The observations are discussed in relation to the function of sulphite reductases in the sulphate-reducing bacteria. Appl Environ Microbiol, 1977 Apr, 33(4), 906 - 10 Oxidative coupling of aromatic pesticide intermediates by a fungal phenol oxidase; Sjoblad RD et al.; The soil fungus Rhizoctonia praticola produced an enzyme that accumulated in the growth medium and caused the polymerization of phenolic and naphtholic intermediates of various pesticides . The dialyzed crude enzyme was purified by ion-exhange column chromatography with diethylaminoethyl-cellulose, followed by gel filtration with Sephadex G-200 . The enzyme, a phenol oxidase, was capable of polymerizing 2-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol, and 4-bromo-2-chlorophenol . 1-Naphthol, 2-naphthol, and some of their derivatives formed oligomers or polymers when incubated with the enzyme, but 4-nitrophenol and 2,4-dinitriphenol were not oxidized . Chlorinated and brominated anilines, which are derivatives of herbicides, were not altered by the phenol oxidase from R . praticola, but 4-methoxyaniline was transformed by the enzyme to 2-amino-5-p-anisidinobenzoquinone-di-p-methoxyphenylimine . The formation of polymeric products was determined by mass spectrometric analysis. Lipids, 1977 Apr, 12(4), 375 - 81 Erucic acid and phospholipids of newborn rat heart cells in culture; Rogers CG; Erucic acid (delta 13-docosenoic acid), labeled with 14C in the 1- or 14-position, was incorporated into fetal calf serum and fed to beating, neonatal rat myocardial cell in culture . Uptake of the docosenoic acid during the first 6 hr of incubation was 41 nM/hr/mg protein in 7-day old cells and 29 nM/hr/mg protein in 14-day old cells . Fifty-seven percent of the 14C-activity was taken up from the medium in 24 hr, of which 77% was in the cells and 23% was unaccounted for . Of the 14C-activity taken up, 26% was in extractable lipid, with two-thirds in neutral lipid and one-third in phospholipid . Within the neutral lipid fraction, 88% of the 14C-activity was present in triglycerides; while in phospholipids, 66% of the 14C-activity was in phosphatidylcholine (PC); 14% in phosphatidylethanolamine (PE); 6% in sphinogomyelin (SPH) and 1% or less in cardiolipin (DPG) . PC had the highest specific activity, followed by SPH and PE . The specific activity of PE was one-half that of SPH when the 14C-erucic acid substrate was labeled at the carboxyl position, but increased to equal that of SPH when the substrate was labeled at the double bond . The fatty acids of PC, PE, and SPH were influenced by erucic acid in the growth medium, but the amounts of each phospholipid were not affected . It is proposed that the altered fatty acid composition associated with incorporation of erucic acid or its metabolites into PC, PE, and SPH may affect integrity and function of heart cell membranes. J Bacteriol, 1977 Apr, 130(1), 485 - 94 Chemotaxis in Spirochaeta aurantia; Greenberg EP et al.; Cell of Spirochaeta aurantia M1 suspended in isotropic buffer solution swam in nearly straight lines and appeared to spin around their longitudinal axis . Occasionally, cells stopped and flexed, and then resumed translational motility, usually in a different direction . The average cell velocity was 26 micron/s . A quantitative assay for chemotaxis was used to test various chemicals for their ability to attract S . aurantia M1 . The cells exhibited a tactic response toward 5 X 10(-2) M D-glucose between 10 and 35degree C; the optimum response was at 25degree C . At 5 degree C motility was not impaired, but D-glucose taxis was abolished . Chemotaxis toward D-glucose was stimulated by L-cysteine (2 X 10(-4) M) . D-Glucose, 2-deoxy-D-glucose, alpha-methyl-D-glucoside, D-galactose, D-fucose, D-mannose, D-fructose, D-xylose, maltose, cellobiose, and D-glucosamine were effectve attractants for S . aurantia M1 . D-Galactose taxis and D-fucose taxis were induced by the presence of D-galactose in the growth medium . The amino acids tested did not serve as attractants, tgrowing cells of S . aurantia M1 exhibited an aerotactic response. Biochim Biophys Acta, 1977 Apr 1, 466(1), 148 - 59 Control of fatty acid composition of Acholeplasma laidlawii membranes; Melchior DL et al.; The temperature-dependent pattern of incorporation of palmitate and oleate from the growth medium into Acholeplasma laidlawii membrane lipids correlates with the physical state of the membrane defined by calorimetry . Both the pattern and the state can be changed at will by changing the fatty acid composition of the membrane lipids . The ratio of palmitate to oleate incorporated is independent of temperature when the membrane bilayer is below its transition and fully ordered, but becomes temperature dependent upon the onset of the transition and continues to be temperature dependent when the membrane is above its transition and fully fluid . This behavior is mimicked by the physical binding of palmitate and oleate to bilayers of extracted membrane lipids and to bilayers of lecithin . Selective binding by membranes may provide a means for controlling lipid fatty acid composition without invoking an enzymatic mechanism. Arch Microbiol, 1977 Apr 1, 112(3), 255 - 61 {Studies on development of the phycomycete Allomyces arbuscula . III . Polysome formation and RNA metabolism during differentiation of gametangia (author's transl)}; Fahnrich P; Polysomes were isolated both from growing gametophytes of Allomyces arbuscula and from gametangia prepared from mycelia at different periods during gametogenesis . Analysis of polysomes by sucrose gradients showed that ribosomes present in the gametangia monosome pool were shifted into polysomes . This shift was found to be correlated with gametangia differentiation . The ribosome distribution remained virtually unchanged during the early stage of gamete formation . In mature gametes and swarming zygotes a low level of polysomes was detected . Labeling of rRNA by 32PO4 demonstrated a de novo synthesis of monosomes throughout the period of gametangia differentiation . No incorporation of 32PO4 was found to be present in ribosomes prepared from gametangia after onset of gamete formation . On the basis of these labeling experiments it is concluded that radioactivity in polysomes extracted from mature gametes and swarming zygotes can be attributed in part to conserved mRNA . Synchronous formation of gametangia was induced by transferring the vegetative mycelia from growth medium into a low salt buffer . Under these conditions the incorporation of either 32PO4 or 3H-uridine into RNA, particularly into rRNA, was found to be markedly decreased . This obviously indicates a shutdown of RNA synthesis . rRNA from induced mycelia examined by polyacrylamide gel electrophoresis was found to be severely degraded . In contrast to this, rRNA isolated from ribosomes of developing gametangia and from gametes exhibited no degradation products . It is suggested that endonucleases cause rRNA hydrolysis in the hyphal cytoplasm during gametangia differentiation . Ribosomes compartmentalized in gametangia seem to be inaccessible to nucleases during the later process for gametogenesis. J Bacteriol, 1977 Apr, 130(1), 472 - 84 Growth and metabolism of inositol-starved Saccharomyces cerevisiae; Henry SA et al.; Upon starvation for inositol, a phospholipid precursor, an inositol-requiring mutant of Saccharomyces cerevisiae has been shown to die if all other conditions are growth supporting . The growth and metabolism of inositol-starved cells has been investigated in order to determine the physiological state leading to "inositolless death" . The synthesis of the major inositol-containing phospholipid ceases within 30 min after the removal of inositol from the growth medium . The cells, however, continue in an apparently normal fashion for one generation (2 h under the growth conditions used in this study) . The cessation of cell division is not preceded or accompanied by any detectable change in the rate of macromolecular synthesis . When cell division ceases, the cells remain constant in volume, whereas macromolecular synthesis continues at first at an unchanged rate and eventually at a decreasing rate . Macromolecular synthesis terminates after about 4 h of inositol starvation, at approximately the time when the cells begin to die . Cell death is also accompanied by a decline in cellular potassium and adenosine triphosphate levels . The cells can be protected from inositolless death by several treatments that block cellular metabolism . It is concluded that inositol starvation results in a imbalance between the expansion of cell volume and the accumulation of cytoplasmic constituents . This imbalance is very likely the cause of inositolless death. Mutat Res, 1977 Apr, 43(1), 1 - 10 Alkaline sucrose sedimentation studies of MMS-induced DNA single-strand breakage and rejoining in the wild type and in UV-sensitive mutants of Saccharomyces cerevisiae; Jachymczyk WJ et al.; MMS-induced DNA single-strand breakage and rejoining was studied in the RAD strain and in rad6 and rad21 mutants, both very sensitive to this treatment as compared with the wild type . Alkaline sucrose gradient centrifugation showed that MMS treatment reduced the molecular weight of DNA in the RAD strain and in rad6 and rad21 mutants to the same extent . Four hours of post-incubation in synthetic growth medium after treatment with a dose of 0.4% MMS which reduces cell survival of RAD, rad21 and rad6 to 50, 20 and less than 0.01%, respectively, resulted in a significant increase in the molecular weight of DNA in the wild type, but in only slight increase in mutant strains . When the strains were exposed to a lower dose of MMS (0.04%) which led to 100% survival of RAD and 50 and 20% survival of rad21 and rad6, respectively, wild-type DNA sedimented to the position of control DNA, while in both mutants the increase in molecular weight of DNA was less pronounced. Appl Environ Microbiol, 1977 Apr, 33(4), 758 - 61 Fungal growth on C1 compounds: quantitative aspects of growth of a methanol-utilizing strain of Trichoderma lignorum in batch culture; Tye R et al.; A study was made of some salient parameters that influence growth of the methanol-utilizing fungus Trichoderma lignorum growing in batch culture on a minimal medium containing methanol as the sole source of carbon . Maximum cell yield was recorded at the expense of 1.58 g of methanol per liter . Inhibition was observed with methanol concentrations in excess of 4.7 g/liter . The optimum temperature for fungal growth was 23 degrees C . Growth of the fungus was directly proportional to an inorganic nitrogen concentration up to 0.2 g of NH4NO3 per liter . No inhibition of growth occurred at any concentration of NH4NO3 up to 11 g/liter . The pH of the growth medium decreased from 7.0 to 3.5 during growth of the fungus on methanol, which may have been due, in part, to the accumulation of trace amounts of organic acids in the growth medium . An analysis of the commercial potential of the fungus, as a source of edible protein, indicated that the strain of methanol-utilizing T . lignorum used was uneconomical in terms of the yield and the specific growth rate. J Bacteriol, 1977 Apr, 130(1), 464 - 71 Morphology of Ureaplasma urealyticum (T-mycoplasma) organisms and colonies; Razin S et al.; 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. J Bacteriol, 1977 Apr, 130(1), 297 - 302 Localization of enzymes in Ureaplasma urealyticum (T-strain mycoplasma); Masover GK et al.; Ureaplasma urealyticum cells were lysed by osmotic shock or by digitonin . The membrane fraction contained four to ten times as much protein as the cytoplasmic fraction . These values are in large excess of those reported for classical mycoplasmas, suggesting that the Ureaplasma membrane fraction was heavily contaminated with proteins derived from the growth medium . The U . urealyticum urease activity was localized in the cytoplasmic fraction, whereas the adenosine triphosphatase activity was localized in the membrane fraction . Significant urease activity could be detected also in nonviable cells . Urea, at concentrations above 0.25 M, was mycoplasmastatic to Acholeplasma laidlawii, Mycoplasma hominis, and U . urealyticum, so that the Ureaplasma urease did not afford preferential protection against urea toxicity . The intracellular localization of the urease would be expected to release ammonia from urea in the cytoplasm . The ammonia will take up protons to become ammonium ions . It can be hypothesized that the intracellular NH4+ plays a role in proton elimination or acid-base balance, which might be coupled to an energy producing ion gradient and/or transport mechanisms. J Bacteriol, 1977 Apr, 130(1), 292 - 6 Effects of carbon dioxide, urea, and ammonia on growth of Ureaplasma urealyticum (T-strain mycoplasma); Masover GK et al.; By use of a simple device for continuous CO2 gassing of Ureaplasma urealyticum cultures growing in a liquid medium, we have been able to separate some of the effects of urea, CO2, ammonia, and pH on growth . The CO2 acted as a superior buffer in the pH range 5.7 to 6.8, which is optimal for Ureaplasma growth . It was, therefore, possible to observe the effect of repeated additions of urea to the culture without alkalinization of the growth medium . We found that the repeated additions of urea did not enhance Ureaplasma growth, and the resultant accumulation of ammonium ions (greater than 2,000 microng/ml) did not cause more rapid death under these conditions . By abruptly changing the gaseous environment from CO2 to N2, it was possible to cause a rapid pH change in the culture to a value above 8.0 . This resulted in a more rapid death of the organisms. Biotechnol Bioeng, 1977 Apr, 19(4), 539 - 54 Growth characteristics of Candida utilis on volatile substrate in a multistage tower fermentor; Paca J et al.; The influence of increasing ethanol concentration in the feed on growth and physiological activity of the yeast Candida utlis was studied . The measurements were made at steady states of continuous culture under constant values of dilution rate, temperature, and pH in all stages of the fermentor; Synthetic ethanol was used as the sole source of carbon and energy in the concentration range 10-100 g/liter . The maximum biomass concentration in the effluent and maximum productivity was achieved at 75 g ethanol/liter in the feed . In respect to ethanol losses in the outlet and biomass yield, the optimum ethanol concentration in the input of the growth medium was found to be about 50 g/liter using a four-stage system. Biochemistry, 1977 Mar 8, 16(5), 944 - 53 Equilibration of fucosyl glycoprotein pools in HeLa cells; Yurchenco PD et al.; The pool sizes, label equilibration times, and specific radioactivity relationships of fucosyl glycoproteins and precursors have been examined in exponentially growing HeLa S3 cells (generation time about 23 h) using a quantitative radioisotopic approach . The specific radioactivity of the precursor GDP-fucose (pool size 0.52 +/- 4% nmol/10(7) cells) equilibrates with radioactive fucose in the medium in about 1 h . 10(7) cells contain 5.3 +/- 16% nmol of glycoprotein fucose of which 96-98% resides in or on the cell surfaces and is equilibrated isotopically within 22 h of labeling; 2% or less is in an internal pool, some of which is precursor to plasma membranes and some of which is released as soluble glycoprotein directly to the medium without random mixing with the plasma membrane glycoprotein . Because we cannot rule out the presence of internal free fucose, 2% of the total glycoprotein fucose could be in the degradative pathway being recycled internally before release of free fucose . In rate terms and in a particular culture where 10(7) cells contained 4.4 nmol of glycoprotein fucose, a total of 11.1 nmol of glycoprotein fucose is synthesized per generation (9-11% of the total cell glycoprotein fucose/h) . Of this, 2.5 nmol of glycoprotein fucose per generation is released directly into the growth medium without mixing with the plasma membrane glycoprotein fucose . The small internal pool feeding glycoprotein fucose to the plasma membrane does so at the rate of 8.6 nmol/10(7) cells per generation, 4.2 nmol per generation of which, after mixing with the plasma membrane glycoprotein fucose, is ultimately released into the growth medium, 75-80% as free frucose . This release process is independent of cell density and the presence of serum in the growth medium. Mikrobiologiia, 1977 Mar-Apr, 46(2), 304 - 10 {Causes of degeneration of cultures of Thermoactinomyces vulgaris}; Kokina VIa et al.; Passage of cultures of Thermoactinomyces vulgaris on a peptone-maize medium causes their degeneration which is manifested in an impaired formation of the sporulating aerial mycelium, and in an increase of the amount of non-germinating spores in populations . The process of degeneration depends on the following conditions: the location of the inoculated material (spores) on the surface of a solid growth medium, which is determined by the technique of inoculation; the state of the spores (degeneration is accelerated if the spores were not activated with low temperatures); the quality of the growth medium. Mikrobiologiia, 1977 Mar-Apr, 46(2), 252 - 6 {Influence of the nutrient medium on the total lipid fatty acid composition of Actinomyces canosus}; Koval'chuk LP et al.; GLC was used to study the composition of endocellular fatty acids of Actinomyces canosus 89 grown on a chemically defined medium and on a complex medium to which various components were added . Total lipids of the culture contain saturated and unsaturated fatty acids, from C13 to C18, with one or two double bonds . Addition of components to the medium stimulated the biosynthesis of myristic, stearic, oleic, and linoleic fatty acids . Changes in the composition of the growth medium modify the ratio between saturated and unsaturated fatty acids of total lipids, increasing the content of unsaturated fatty acids due to a higher rate of synthesis of linoleic and oleic fatty acids . An increase in the content of unsaturated fatty acids is a positive factor because these acids are involved in important physiological functions of both this organism and other living organisms. Cell Tissue Kinet, 1977 Mar, 10(2), 127 - 35 Relationship of nutritional factors to in vitro tumor cell growth and cytotoxicity produced by cytosine arabinoside; Momparler RL et al.; The in vitro relationship between nutritional factors, proliferative status of tumor cells, and the cytotoxic action of cytosine arabinoside (ara-C) was investigated . The reduction in the concentration of only one essential amino acid, L-isoleucine, in the growth medium of A(T1)C1-3 hamster fibrosarcoma cells decreased DNA synthesis in this cell population and slowed the rate of progression of G1 phase cells into S phase of the cell cycle . The complete omission of isoleucine from the growth medium blocked the progression of G1 phase cells into S phase and prevented the cytotoxic action of ara-C . The addition of isoleucine to the isoleucine-deprived cells permitted these cells to enter the S phase and restored their sensitivity to the cytotoxic action of ara-C . When G1 phase cells were placed in a medium containing reduced levels of all the amino acids and vitamins there was a prolongation of the G1 phase . Since medium with low levels of amino acids produced a delay in the entry of G1 phase cells into the S phase, the time interval in which these cells were most sensitive to the cytotoxic action of ara-C was different for G1 phase cells placed in medium with adequate levels of all the amino acids . These in vitro data indicate that nutritional factors can markedly effect the proliferation of tumor cells and the cytotoxic action of ara-C. J Biol Chem, 1977 Feb 25, 252(4), 1257 - 63 Novel enzymic machinery for the metabolism of oxalacetate, phosphoenolpyruvate, and pyruvate in Pseudomonas citronellolis; O'Brien R et al.; The metabolic pathways for the interconversion of oxalacetate, phosphoenolpyruvate, and pyruvate in Pseudomonas citronellolis form an interlocking system (Scheme 1) that would appear to require complex regulatory mechanisms to permit a proper flow of metabolites through the pathways and to prevent futile cycling . Oxalacetate decarboxylase (I in Scheme 1), P-enolpyruvate synthase (II), P-enolpyruvate carboxylase (III), and pyruvate kinase (V) are constitutive enzymes in this organism . Pyruvate carboxylase (VI) is inducible and has its highest activity in cells grown on glucose or lactate, moderate activity in cells grown on acetate, citrate, or glutamate, and virtually no activity in aspartate-grown cells . P-enolpyruvate carboxykinase (IV) was not detected . The presence of these five enzymes in a single cell has not been previously reported . In Scheme 1, three futile cycles are possible: the simultaneous operation of Reactions I and VI; of Reactions II and V; or of I, II, and III . An examination of the regulatory properties of the individual enzymes after partial purification offers support for the hypothesis of an intricate regulatory system . Oxalacetate decarboxylase (I) is inhibited by acetyl-CoA; phosphoenolpyruvate carboxylase (III) is activated by acetyl-CoA and ADP and inhibited by aspartate; phosphoenolpyruvate synthase (II) is inhibited by 5'-AMP and phosphoenolpyruvate; and pyruvate kinase (V) is activated by 5'-AMP and 2 keto, 3-deoxy,6-phosphogluconate and inhibited by ATP . The presence of metabolites with reciprocal but reinforcing functions is noteworthy . As an example, acetyl-CoA both inhibits the breakdown of oxalacetate and stimulates its formation . Only pyruvate carboxylase appears to be regulated by the carbon substrates of the growth medium. J Biol Chem, 1977 Feb 10, 252(3), 878 - 82 Metabolic regulation of aminoacyl-tRNA synthetase biosynthesis in bakers' yeast; Johnson RC et al.; The specific activities of 15 aminoacyl-tRNA synthetases in Saccharomyces cerevisiae were measured after growth under a variety of conditions that produced a range of cell-doubling times . The specific activity of each synthetase increased as cell-doubling time decreased . Control experiments eliminate the possibility that these results are due to preferential recovery of synthetases, or to the presence of activators in the faster growing cultures or inhibitors in the slower growing ones . These observations run counter to the expectation that synthetases in bacteria and yeast are negatively regulated by free amino acids, or, more likely, by aminoacyl-tRNA . In fact, as the growth medium was enriched, generation times decreased, and synthetase and aminoacyl-tRNA levels increased . It is suggested that cytoplasmic aminoacyl-tRNA synthetases may be more or less coordinately controlled such that their response to growth follows the pattern observed for ribosome production and RNA synthesis . This suggests the possibility of coordinated response of genes for components of the protein synthetic apparatus. Arch Microbiol, 1977 Feb 4, 112(1), 57 - 9 The cell content and secretion of water-soluble vitamins by several freshwater algae; Aaronson S et al.; Three green algae, Chlamydomonas reinhardii, Chlorella vulgaris and Scenedesmus obliquus, and one blue-green alga, Anabaena cyclindrica, were grown in chemically defined media . All the algae examined contained folates, beta-carotene and vitamins C and E; several of the B-vitamins and vitamin A were found in varying amounts in some but not in all the algae examined . All the green algae secreted significant amounts of folate and biotin and all but Scenedesmus secreted pantothenate into their growth medium; Anabaena secreted folate and pantothenate. J Gen Microbiol, 1977 Feb, 98(2), 587 - 93 The effect of growth and urea concentration on ammonia production by a urea-hydrolysing mycoplasma (Ureaplasma urealyticum); Masover GK et al.; 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 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 degrees C) or in an inadequate growth medium at 37 degrees C . 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 ureaplasms which depend on detecting ammonia colorimetrically. J Bacteriol, 1977 Feb, 129(2), 866 - 73 Control of arginine utilization in Neurospora; Weiss RL et al.; The response of Neurospora to changes in the availibility of exogenous arginine was investigated . Upon addition of arginine to the growth medium, catabolism is initiated within minutes . This occurs prior to expansion of the arginine pool or augmentation of catabolic enzyme levels . (Basal levels are approximately 25% of those found during growth in arginine-supplemented medium.) Catabolism of arginine is independent of protein synthesis, indicating that the catabolic enzymes are active but that arginine is not available for catabolism unless present in the medium . Upon exhaustion of the supply of exogenous arginine, catabolism ceases abruptly, despite an expanded arginine pool and induced levels of the catabolic enzymes . The arginine pool supports protein synthesis until the cells regain their normal capacity for endogenous arginine synthesis . These observations, combined with the known small level of induction of arginine catabolic enzymes, non-repressibility of most biosynthetic enzymes, and vesicular localization of the bulk of the arginine pool, suggest that compartmentation plays a significant role in controlling arginine metabolism in Neurospora. J Cell Physiol, 1977 Feb, 90(2), 233 - 40 Differential effects of inhibitors of cell division upon the growth stimulating activities of insulin and serum in nutritionally depleted human and mouse cells; Kamely D; 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. Infect Immun, 1977 Feb, 15(2), 510 - 7 Evaluation of experimentally induced Fusobacterium necrophorum infections in mice; Conlon PJ et al.; Two strains of mice, Swiss Webster and DBA/2Cr, were injected intraperitoneally or intravenously with varying dosages of Fusobacterium necrophorum . The ability to eliminate the infection was assessed by quantitative enumeration of the organisms present in the blood, liver, and spleen, Three- to 4-week-old DBA/2Cr mice were highly resistant to both routes of injection . The intraperitoneal injection of older mice failed to demonstrate a dose-effect relationship whereas an intravenous injection of as few as 10(4) cells of F . necrophorum produced progressively necrotic leg abscesses, apparently involving the lymphonodus ischiadicus which filters the site of injection . Mortality was increased with sensitization by a previous sublethal injection . Also, an ethanol-killed cell vaccine delayed the onset of lethal infection, whereas repeated sublethal live cell injections provided nonspecific protection since mice vaccinated with the growth medium were equally protected . The development of leg abscesses after intravenous injection visibly demonstrated the pathogenicity of F . necrophorum and may provide a suitable model for the evaluation of vaccines and the effectiveness of antibiotics. J Bacteriol, 1977 Feb, 129(2), 798 - 802 Developmentally induced autolysis during fruiting body formation by Myxococcus xanthus; Wireman JW et al.; The developmental events during fruiting body construction by the myxobacterium M . xanthus is an orderly process characterized by several sequential stages: growth leads to aggregation leads to formation of raised, darkened mounds of cells leads to autolysis leads to myxospore induction . The temporal sequence of autolysis followed by myxospore induction is consistent with the interpretation that developmental autolysis provides essential requirements for the surviving cells to induce to myxospores . At intermediate developmental times on agar plates a fraction of the cell population is irreversibly committed to lyse; i.e., lysis continues in liquid growth medium or in magnesium-phosphate buffer . Lysis is cell concentration independent and is therefore likely to be by an autolytic mechanism . The lysis sequence can be preliminarily characterized as having an early stage during which deoxyribonucleic acid synthesis continues and a later irreversible stage during which deoxyribonucleic acid synthesis does not occur . Irreversible lysis in liquid growth medium or in magnesium-phosphate buffer is initiated on agar plates during nutrient deprivation and such lysis results in the induction of a fraction of the population to myxospores . This induction is dependent upon the concentration of lysis products, thus providing evidence that developmentally induced autolysis is required for myxospore induction. J Cell Physiol, 1977 Feb, 90(2), 307 - 20 A serum factor requirement for the passage of cultured Vero cells through G2; Engelhardt DL et al.; 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. Biochem J, 1977 Feb 1, 161(2), 357 - 70 Solubilization, partial purification and properties of N-methylglutamate dehydrogenase from Pseudomonas aminovorans; Bamforth CW et al.; 1 . Extracts of amine-grown Pseudomonas aminovorans contained a particle-bound N-methylglutamate dehydrogenase (EC 1.5.99.5) . The enzyme was not present in succinate-grown cells, and activity appeared before growth began in succinate-grown cells which had been transferred to methylamine growth medium . 2 . Membrane-containing preparations from methylamine-grown cells catalysed an N-methylglutamate-dependent uptake of O2 or reduction of cytochrome c, which was sensitive to inhibitors of the electron-transport chain . 3 . N-Methylglutamate dehydrogenase activity with phenazine methosulphate or 2,6-dichlorophenol-indophenol as electron acceptor could be solubilized with 1% (w/v) Triton X-100 . The solubilized enzyme was much less active with cytochrome c as electron acceptor and did not sediment in 1 h at 150000g . Solubilization was accompanied by a change in the pH optimum for activity . 4 . The solubilized enzyme was partially purified by Sepharose 4B and hydroxyapatite chromatograpy to yield a preparation 22-fold increased in specific activity over the crude extract . 5 . The partially-purified enzyme was active with sarcosine, N-methylalanine and N-methylaspartate as well as with N-methylglutamate . Evidence suggesting activity with N-methyl D-amino acids as well as with the L-forms was obtained . 6 . The enzyme was inhibited by p-chloromercuribenzoate, iodoacetamide and by both ionic and non-ionic detergents . 2-Oxoglutarate and formaldehyde were also inhibitors . 7 . Kinetic analysis confirmed previous workers' observations of a group transfer (Ping Pong) mechanism . 8 . Spectral observations suggested that the partially purified preparation contained flavoprotein and a b-type cytochrome . 9 . The role of the enzyme in the oxidation of methylamine is discussed. Infect Immun, 1977 Feb, 15(2), 518 - 26 Levan and levansucrase of Actinomyces viscosus; Pabst MJ; A levansucrase was demonstrated in the growth medium and in association with the cell surface of Actinomyces viscosus . The amount of enzyme produced relative to cell density is not significantly affected by the growth conditions . Sugar alcohols inhibit growth of the cells . The levansucrase hydrolyzes sucrose to produce free glucose and levan; some free fructose is also formed . There is no requirement for cofactors . The Km for sucrose is 12 mM . A variety of heavy metal ions and two disaccharides, lactose and cellobiose, inhibit the enzyme . The levansucrase was purified to homogeneity and has a specific activity of 90 micronmol of glucose release per min per mg . The enzyme has a molecular weight of 220,000 and is composed of subunits of molecular weight 80,000 . The levan product contains both beta(2 leads to 1) and beta(2 leads to 6) linkages . The enzyme remains tightly bound to the levan product, resulting in the formation of high-molecular-weight polymer on the order of 10(8) daltons . The possible role of the levan and levansucrase of A . viscosus in the pathogenesis of periodontal disease is discussed. J Immunol Methods, 1977, 17(3-4), 211 - 6 A simple technique for studying immunoglobulin synthesis by normal and malignant plasma cells in vitro; Pritchard S et al.; Plasma cells from human marrows are saturated with C-14 labelled amino acids, harvested and recultured in unlabelled growth medium . The appearance of radioactivity in the growth medium then provides a simple and rapid measure of protein synthesis . The secreted radio-labelled material is characterized by isoelectric focusing and autoradiography in acrylamide gels, a technique which has advantages over established serological methods. J Supramol Struct, 1977, 6(2), 179 - 89 Role of the membrane potential in serum-stimulated uptake of amino acid in a diploid human fibroblast; Vilereal ML et al.; The Na+-dependent accumulation of alpha-aminoisobutyric acid (AIB), measured in normal growing and quiescent (serum-deprived) HSWP cells (human diploid fibroblast), was found to be twofold higher (AIB/in/AIBout = 20-25) under the normal growing conditions . Serum stimulation of quiescent cells increases their AIB concentrating capacity by approximately 70% within 1 hr . These observations suggest that the driving forces for AIB accumulation may be reversibly influenced by the serum concentration of the growth medium . Addition of valinomycin (Val) to cells preequilibrated with AIB causes an enhanced accumulation of AIB, suggesting that the membrane potential can serve as a driving force for AIB accumulation . After preequilibration with AIB in 6 mM K+, transfer to 94 mM K+ with Val results in a marked and rapid net loss of AIB . The effect of Val on the accumulation of AIB is greatest in quiescent cells, with the intracellular AIB concentrations reaching those seen both in Val-stimulated normal cells and in Val-stimulated serum-stimulated cells . By adjusting {K+}0, in the presence of Val, the membrane potential of growing cells can be matched to that of quiescent cells or vice versa . When this is done, the two accumulate AIB to the same extent . Hence the AIB accumulating capacity is characteristic of the membrane potential rather than of the growth state . In summary, these data suggest that the accumulation of AIB in HSWP cells is influenced by changes in membrane potential and that a serum-associated membrane hyperpolarization could be responsible for the increased capacity for AIB accumulation in serum-stimulated cells. Eur J Biochem, 1977 Jan, 72(2), 385 - 92 Fate of histone messenger RNA in synchronized HeLa cells in the absence of initiation of protein synthesis; Stahl H et al.; The fate of cytoplasmic histone mRNA was studied under conditions in which initiation of protein synthesis in synchronized HeLa cells is S phase was blocked by increasing the osmolarity of the growth medium with NaCl . In contrast to the interruption of DNA replication with hydroxyurea, which results in an exponential degradation of translatable histone mRNA with a half-life of about 10-13 min, blocking the initiation of protein synthesis leads to only a marginal loss of biologically active histone mRNA in the cytoplasm . When the initiation of protein synthesis was interrupted by treating cells with 150 mM NaCl, 40-50% of the total cytoplasmic histone mRNA previously translated in polyribosomes appears in the cytoplasm integrated into mRNA-protein particle(s) sedimenting between 15 S and 30 S . On the other hand, in untreated S-phase cells or in cells blocked with hydroxyurea only 3-6% of the total translatable histone mRNA is found in the cytoplasm not bound to ribosomes or their subunits . In addition, the degradation of histone mRNA in hydroxyurea-blocked S-phase cells is prevented when the initiation of protein synthesis is inhibited with NaCl . These studies clearly indicate that the inhibition of initiation of protein synthesis per se is not the cause for the rapid degradation of cytoplasmic histone mRNA observed when DNA replication is turned off and that the inactivation of these mRNAs is a process dependent on continuous protein synthesis. J Supramol Struct, 1977, 6(4), 571 - 7 Sialic acid uptake by BHK cells and subsequent incorporation into glycoproteins and glycolipids; Hirschberg CB et al.; BHK cells can be grown in the presence of growth medium to which radiolabeled sialic acid has been added . After 24 h, 85 percent of the radioactivity in the cells is covalently bound to glycoproteins and glycolipids . No metabolism of the radiolabeled sialic acid could be detected. Arch Virol, 1977, 54(4), 333 - 43 Persistent infection of BHK21/WI-2 cells with rubella virus and characterization of rubella variants; Sato M et al.; Persistently infected cell lines of BHK21/WI-2 cells have been established by infection with the wild type rubella virus strain M-33 . These cell lines, BHK-MP1 and BHK-MP2, showed immunity-like resistance to superinfection with M-33 virus at both 34 degrees and 39.5 degrees C . They also showed intrinsic interference with the replication of Newcastle Disease Virus at 34 degrees C but not at 39.5 degrees C . They released a small number of infectious virus particles which were temperature sensitive variants, being able to form plaques at 34 degrees C, but not at 39.5 degrees C on BHK21/WI-2 and on its derivative, BSR . When BHK-MP1 cells were cultured at 34 degrees C in growth medium containing 10--20 microgram/ml of 5-bromodeoxyuridine (BudR) there was a 5- to 10-fold increase in infectious virus in the medium as compared with the untreated controls . Mitomycin C (0.5 microgram/ml) treatment for 7 hours likewise stimulated the release of virus from these cells . The enhancement of viral release by BudR was completely blocked by pretreatment with actinomycin D (5 microgram/ml) for 3 hours prior to BudR treatment . Since the variant can be induced by these prophage inducers and inhibited by actinomycin D it is suggested that the viral genome is converted to a DNA provirus which is analogous to the lysogenic state of bacteriophage. Natl Inst Anim Health Q (Tokyo), 1977 Summer, 17(2), 54 - 7 Chicken kidney cell culture in medium without serum; Yamaguchi S et al.; 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 0.3% 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. Genetics, 1977 Jan, 85(1), 35 - 54 The effect of ochre suppression on meiosis and ascospore formation in Saccharomyces; Rothstein RJ et al.; The effect of altered tyrosyl-tRNAs on the developmental process of sporulation was examined . Mutations in eight independent loci resulting in tyrosine-inserting nonsense suppressor were tested for their effects on sporulation . Different levels of inhibition were found ranging from SUP3-omicron, which caused the greatest reduction of sporulation (7-17% of wild type), to SUP11-omicron which caused no reduction in sporulation . Since the SUP3-omicron mutation exhibited the greatest effect, it was studied in detail . Although SUP3-omicron is a dominant nonsense suppressor, its effect on sporulation is recessive . Expression of the sporulation deficiency is dependent upon the stage of transfer from glucose growth medium (i.e., log, early stationary, etc.) to sporulation medium . SUP3-omicron/SUP3-omicron diploid cells transferred from log or early stationary phase are capable of sporulation, whereas cells transferred after early stationary phase (i.e., after adaptation to respiration) exhibit poor sporulative ability . Sporulation events were examined under restrictive conditions to observe those events completed by SUP3-omicron/SUP3-omicron diploids . The early events of sporulation occur in these cells . Later events are completed by progressively fewer cells . Premeiotic DNA synthesis occurred in approximately 40% of the cells, nuclear segregation occurred in 20%, and finally, only 2% formed asci . The fact that fewer late-sporulation events occur under restrictive conditions can be explained by increased efficiency of suppression. J Gen Microbiol, 1977 Jan, 98(1), 177 - 86 Fluctuations in buoyant density during the cell cycle of Escherichia coli K12: significance for the preparation of synchronous cultures by age selection; Poole RK; The buoyant densities of Escherichia coli K12 were investigated by isopycnic centrifugation in gradients of colloidal silica (Ludox) and polyvinylpyrrolidone . Bacteria from an exponential culture in a defined medium supplemented with hydrolysed casein banded at densities between 1-060 and 1-115 g ml-1; the mean density was 1-081 g ml-1 . At the higher densities, two populations of cells were present: smaller cells were approximately twice as numerous as, and half the modal volume of, the population of larger cells . A homogeneous population of cells of intermediate volume equilibrated in the least dense region of the density band . Synchronous cultures were established by inoculating cells selected from the most or least dense regions of the band into spent growth medium . The results are consistent with a fluctuation between maximal density at cell birth and division, and minimal density near the middle of the cell cycle . In synchronous cultures prepared by continuous-flow age selection, the first division occurred after a period that was significantly shorter than the length of subsequent cell cycles . Cells selected by this procedure were of similar mean density to those in the exponential culture but were more homogeneous with respect to size . The possibility that the smallest (and densest) cells in an exponential culture are retained in the rotor, and are thus excluded from the synchronous culture, is discussed. Antonie Van Leeuwenhoek, 1977, 43(2), 153 - 67 ATP formation associated with fumarate and nitrate reduction in growing cultures of Veillonella alcalescens; de Vries W et al.; Molar growth yields, fermentation balances and enzyme activities were measured in Veillonella alcalescens grown anaerobically with different substrates in the absence or presence of fumarate or nitrate . The molar growth yields on malate (14.3 g dry wt bacteria/mole substrate) and citrate (19.3) were higher than that on lactate (8.6) . The molar growth yield on lactate was increased to 15.5 or 19.8 by the addition of fumarate or nitrate, respectively, to the growth medium, and the molar growth yield on citrate was increased to 25.3 by addition of nitrate . Active growth on pyruvate was only observed in the presence of nitrate, and the molar growth yield was 25.5 . From fermentation balances and fermentation systems similar YATP values (g dry wt bacteria/mole ATP) were calculated for all substrates or mixtures of substrates assuming that one mole of ATP is generated at the electron transport from pyruvate, NADH and NADPH to nitrate or fumarate whereas ATP is not produced in the electron transport from lactate to fumarate or nitrate, and, therefore, this assumption was considered to reflect the actual situation . The mean YATP value at a doubling time of 1 h was 16.5 g dry wt bacteria/mole ATP for growth without an added hydrogen acceptor, 14.4 for growth with fumarate, and 14.2 for growth with nitrate. Intervirology, 1977, 8(4), 204 - 17 Further biological properties of the human syncytial virus; Loh PC et al.; Some biological properties of the human syncytial virus have been examined . A 13-day plaque assay in whole human embryo fibroblasts (HEF) has been developed using a liquid (growth medium) overlay . The plaques were 0.7-2 mm in diameter and often showed a clear central zone with irregular edges . Pretreatment of HEF monolayers with the polycation DEAE-dextran for either 30 min or 1 h was found to enhance plaque formation by a factor of from 2- to 7-fold . The plaque assay procedure required cell cultures undergoing active cell division . Adsorption kinetics and growth cycle studies in HEF indicated a relatively long adsorption period (3 h) and a relatively prolonged latent period of 24 h . Even under optimal conditions, virus yields were low and did not exceed 1 PFU per infected cell . Like other animal syncytium-forming 'foamy' viruses, the human virus induced both intranuclear and cytoplasmic antigens detectable by immmunofluorescence and was also markedly labile to freezing and thawing. J Supramol Struct, 1977, 6(3), 363 - 74 Defective transport of thymidine by cultured cells resistant to 5-bromodeoxyuridine; Lynch TP et al.; A line of HeLa cells resistant to 5-bromo-2'-deoxyuridine (BUdR) was established by continuous culture in growth medium containing BUdR; during the selection period, BUdR concentrations, initially 15 micrometer, were gradually increased to 100 micrometer . Cells of a clone (HeLa/B5) established from this line were also resistant to 5-fluoro-2'-deoxyuridine (FUdR), but not to the free base, 5-fluorouracil . Although extracts of HeLa/B5 cells exhibited levels of thymidine kinase activity comparable to those of parental cells, rates of uptake of BUdR, FUdR, and thymidine into intact cells were much reduced . The kinetics of uptake of uridine and adenosine, nucleosides which appear to be transported independently of thymidine in HeLa cells, were similar for HeLa/B5 and the parental line (HeLa/O) . Relative to thymidine uptake by HeLa/O cells, that by HeLa/B5 cells was distinctly less sensitive to nitrobenzylthioinosine (NBMPR), a specific inhibitor of nucleoside transport in various types of animal cells . Despite this difference in NBMPR sensitivity, both cell lines possessed the same number of high affinity NBMPR binding sites per mg cell protein . The altered kinetics of thymidine uptake and the NBMPR insensitivity of that function in HeLA/B5 cells suggest that resistance to BUdR is due to an altered thymidine transport mechanism. Acta Microbiol Pol, 1977, 26(1), 59 - 64 Formylation and acetylation of 4-chloroaniline by a Streptomyces sp; Russel S et al.; 4-Chloroaniline was metabolized in a liquid growth medium by a Streptomyces sp . which was isolated from soil . After 60 gours of incubation the aniline had disappeared and several metabolites could be detected by thin layer chromatographic analysis . 4-Chloroformylaniline and 4-chloroacetanilide were identified as products . The formation of a formylanilide by the actinomycete indicates a new mechanism of microbial aniline transformation. J Virol, 1977 Jan, 21(1), 328 - 37 Viral protein synthesis in Friend erythroleukemia cell lines; Racevskis J et al.; Viral protein synthesis was studied in two Friend virus-induced erythroleukemia cell lines (Ostertag cell lines FSD1-F4 and B8) by the technique of immuno-precipitation with monospecific antisera to the major envelope glycoprotein gp70 and major core protein p30 . One of the cell lines (F4) releases active Friend virus complex to the growth medium, where release of virus from the other cell line (B8) is barely or nondetectable . It was found that in the nonproducer cell line B8, a large-molecular-weight protein of about 65,000 containing p30 antigenic determinants is synthesized, yet no p30 is produced upon prolonged incubation and chase, suggesting that this might be the actual lesion that prevents mature virus production by these cells . In both cell lines, the predominant protein species that is immunoprecipitated with monospecific anti-gp70 serum is a protein of 55,000 to 60,000 daltons that is labeled with glucosamine to a much lesser extent that gp70 and appears to become heterogeneous with time . Large amounts of gp70 can be detected in the cell-free medium, but none of the unstable species of 55,00 to 60,000 molecular weight. J Virol, 1977 Jan, 21(1), 366 - 74 Role of the pneumococcal autolysin (murein hydrolase) in the release of progeny bacteriophage and in the bacteriophage-induced lysis of the host cells; Ronda-Lain C et al.; The pneumococcal bacteriophage Dp-1 seems to require the activity of the N-acetylmuramic acid-L-alanine amidase of the host bacterium for the liberation of phage progeny into the medium . This conclusion is based on a series of observations indicating that the exit of progeny phage particles is prevented by conditions that specifically inhibit the activity of the pneumococcal autolysin . These inhibitory conditions are as follows: (i) growth of the bacteria on ethanolamine-containing medium; (ii) growth of the cells at pH values that inhibit penicillin-induced lysis of pneumococcal cultures and lysis in the stationary phase of growth; (iii) addition of trypsin or the autolysin-inhibitory pneumococcal Forssman antigen (lipoteichoric acid) to the growth medium before lysis; (iv) infection of an autolysin-defective pneumococcal mutant at a multiplicity of infection less than 10 (treatment of such infected mutant bacteria with wild-type autolysin from without can liberate the entrapped progeny phage particles); (v) release of phage particles and culture lysis can also be inhibited by the addition of chloramphenicol to infected cultures just before the time at which lysis would normally occur . Bacteria infected with Dp-1 under conditions nonpermissive for culture lysis and phage release secrete into the growth medium a substantial portion of their cellular Forssman antigen in the form of a macromolecular complex that has autolysin-inhibitory activity . We suggest that a phage product may trigger the bacterial autolysin by a mechanism similar to that operating during treatment of pneumococci with penicillin (Tomasz and Waks, 1975). Biochemistry, 1976 Dec 14, 15(25), 5443 - 8 Effect of VP-16-213 on the intracellular degradation of DNA in HeLa cells; Loike JD et al.; The effect of VP-16-213 on cellular DNA was studied by following the sedimentation profiles of radioactive DNA in HeLa cells on alkaline sucrose gradients . In VP-16-213 treated cells, high-molecular-weight DNA is converted to a lower molecular-weight form in a dose-dependent, temperature-dependent reaction . The effect of VP-16-213 on cellular DNA is reversed after the drug has been removed from the growth medium for 150 min . These results suggest that VP-16-213 induces single-stranded breaks in DNA in HeLa cells and that HeLa cells can repair these breaks within 150 min . The nonglucoside derivative of VP-16-213, 4'-demethylepipodophyllotoxin, also induces the cleavage of cellular DNA but podophyllotoxin has no effect on DNA . A structure-activity relationship study, in which the effects of various VP-16-213 and podophyllotoxin congeners were tested for their ability to cleave cellular DNA,revealed that an hydroxyl group at the C-4' position is required for activity and that the configuration of the C-4 carbon influences the activity of a congener . These results may offer insights into the mechanism of action of VP-16-213 as an antitumor agent. Dev Biol Stand, 1976 Dec 13-15, 37, 77 - 82 Problems related to the use of serum and trypsin in the growth of monkey kidney cells; Melnick JL et al.; A function of serum in the growth medium for primary monkey kidney cells has been shown to be inhibition of proteolytic enzymes . Serum inactivates the residual trypsin remaining from enzymatic digestion of the kidneys and the proteolytic enzymes subsequently synthesized by the cells . Freshly trypsinized cells could be grown to monolayers in the absence of serum provided that they were repeatedly washed to remove residual trypsin . In the absence of serum, cell growth ceased on the 4-5th day after initiation of the culture, at which time the culture fluids became active proteolytically . When the 5th day fluids were replaced with fresh serum-free medium, cell growth was accelerated and a monolayer was attained by the 7th day . If cells were grown in the absence of whole serum but in the presence of medium containing alpha globulins or fetuin which inhibit both trypsin and cell proteases, such cultures grew as well as cultures containing serum . The sterilization of trypsin for use in digestion of tissues and cell cultures poses a serious problem . After filtration through 0.22 micron filters, trypsin preparations may still contain adventitious viruses, mycoplasma and minute forms of pseudomonas and other bacteria or bacteria-produced toxins, which pass the membrane pores . A process of purifying and sterilizing trypsin without deleteriously affecting its proteolytic activity is described. Acta Radiol Ther Phys Biol, 1976 Dec, 15(6), 551 - 9 Radiation sensitizing effect of diamide on human cells cultivated in vitro; Pettersen EO et al.; Human cells of line NHIK 3025 were irradiated suspended in growth medium (E2a) in absence and presence of diamide under aerobic and extremely hypoxic (less than 4 ppm O2) conditions . A sensitizing effect of diamide was found for doses exceeding 8 Gy (800 rad) on cells irradiated under extremely hypoxic conditions in presence of diamide of concentration 200 micrometer, whereas no significant effect was observed for 20 micrometer. J Clin Microbiol, 1976 Dec, 4(6), 492 - 502 Cellular fatty acids and metabolic products of Pseudomonas species obtained from clinical specimens; Moss CW et al.; The cellular fatty acid composition of 112 reference strains and clinical isolates of Pseudomonas species was determined by gas-liquid chromatography (GLC) . The presence and relative amounts of cyclopropane, hydroxy, and branched-chain fatty acids were distinguishing features of these strains . Determination of short-chain fatty acids extracted from spent growth media provided an additional means for identifying some strains . Our results show that clinical isolates of pseudomonads can be divided into eight distinct GLC groups . The procedures were especially useful for distinguishing glucose-nonoxidizing pseudomonads, which are difficult to identify by conventional criteria . Since the GLC procedures are simple, rapid, and highly reproducible, they are useful in diagnostic laboratories that process large numbers of cultures . Coupled with selected conventional tests, the analysis of short-chain and cellular fatty acids can be very useful for rapid screening of clinical isolates of Pseudomonas species. J Bacteriol, 1976 Dec, 128(3), 708 - 16 Chromosome segregation in Escherichia coli B/r at various growth rates; Pierucci O et al.; Chromosome segregation was analyzed in three substrains of Escherichia coli B/r growing at various rates . The cultures were pulse labeled with {14C}thymidine and bound to the bottom surface of a nitrocellulose membrane filter, and the radioactivity in newborn cells released from the surface during continuous elution with growth medium was measured . Since there was a fixed orientation in the release of newborn cells, the time course of the change in radioactivity per effluent cell could be used to investigate the orientation of chromosome segregation . If the radioactive deoxyribonucleic acid strands were partitioned at random between the progenies remaining attached to the membrane filter and those released into the effluent, the radioactivity per cell would decrease twofold after each generation of elution . The decrease in radioactivity was less than twofold at C + D min of elution and larger than twofold one generation later, indicating that chromosome segregation was nonrandom. J Cell Physiol, 1976 Dec, 89(4), 677 - 81 Sodium: a regulator of glucose uptake in virus-transformed and nontransformed cells; Bader JP; Observations of cells transformed by the Bryan strain of Rous sarcoma virus (RSV-BH) suggested that the intracellular concentrations of sodium ion (Na+) may play a critical role in cellular metabolism . In an attempt to manipulate intracellular Na+, chick embryo cells were exposed to graded concentrations of Na+ in the cellular growth medium, and the effects on capacity for glucose uptake was examined . After incubation for six hours, the incorporation rate of 2-deoxyglucose (used as a substitute for glucose) was proportional to the external Na+ concentration over the range, 100 mM to 200 mM . Cells transformed by RSV-BH were less responsive than nontransformed cells to differences in Na+ at low concentrations . The changes were specifically dependent upon Na+, since K+, Li+, or choline + were ineffective as substitutes, and increasing the ionic strength above that of 120 mM Na+ was effective only when Na+ was the added cation. Biochemistry, 1976 Nov 30, 15(24), 5228 - 33 Molecular control of membrane properties during temperature acclimation . Membrane fluidity regulation of fatty acid desaturase action? Kasai R, Kitajima Y, Martin CE, Nozawa Y, Skriver L, Thompson GA Jr. Further studies on the molecular mechanisms of temperature acclimation have been carried out using the ciliate Tetrahymena pyriformis . The most prominent change in lipid metabolism during acclimation to high temperature--depression of fatty acid desaturase activity--could be simulated by supplementing the growth medium of isothermally-grown cells with polyunsaturated fatty acids . Such cells resisted the membrane-fluidizing effect of the incorporated exogenous acids by increased use of de novo synthesized saturated acids in their phospholipids . The data support the conclusions arising from earlier experiments with temperature-shifted cells (Martin, C.E., Hiramitsu, K., Kitajima, Y., Nozawa, Y., Skriver, L., and Thompson, G.A., Jr . (1976), Biochemistry 15), showing that, when membrane fluidity increased to a superoptimal level, the activity of membrane-associated fatty acid desaturases was decreased . Since the reaction is controlled by membrane fluidity, rather than temperature per se, we postulate that it is the general mechnaism employed by cells adjusting to any fluidity-modifying factor, such as cations, drugs, etc. Biochem J, 1976 Nov 15, 160(2), 305 - 14 One-carbon metabolism in Neurospora crassa wild-type and in mutants partially deficient in serine hydroxymethyltransferase; Cossins EA et al.; 1 . The concentrations of folate-dependent enzymes in Neurospora crassa Lindegren A wild type (FGSC no . 853), Ser-l mutant, strain H605a (FGSC no . 118), and for mutant, strain C-24 (FGSC no . 9), were compared during exponential growth on defined minimal media . Both mutants were partially lacking in serine hydroxymethyltransferase, but contained higher concentrations of 10-formyltetrahydrofolate synthetase than did the wild type . Mycelia of the mutants contained higher concentrations of these enzymes when growth media were supplemented with 1mM-glycine . In the wild-type, this glycine supplement also increased the specific activities of 5,10-methylenetetrahydrofolate dehydrogenase and 5,10-methylenetetrahydrofolate reductase . 5 . During growth, total folate and polyglutamyl folate concentrations were greatest in the wild-type . Methylfolates were not detected in mutant Ser-l, and were only present in the for mutant after growth in glycine-supplemented media . Exogenous glycine increased folate concentration threefold in the wild type, mainly owing to increases in unsubstituted polyglutamyl derivatives . 3 . Feeding experiments using 14C-labelled substrates showed that C1 units were generated from formate, glycine and serine in the wild type . Greater incorporation of 14C occurred when mycelia were cultured in glycine-supplemented media . Formate and serine were precursors of C1 units in the mutants, but the ability to cleave glycine was slight or lacking. Atherosclerosis, 1976 Nov-Dec, 25(2-3), 205 - 12 Lipid metabolism in cultured aortic smooth muscle cells and comparison with other cell types . Part 2 . Reversibility of lipid accumulation caused by hyperlipemic serum; Pearson JD; The lipid compositions of cultured rabbit aortic smooth muscle cells and skin fibroblasts were determined for cells grown in media containing either normolipemic or hyperlipemic sera . Both cell types accumulated cholesteryl esters and triglycerides after treatment with hyperlipemic serum . Within 4 days of returning cells that had accumulated these neutral lipids to medium containing a low percentage of normolipemic serum, their concentrations in both cell types had returned to levels similar to those found in cells cultured in standard growth medium . Thus the accumulation of cholesteryl esters and triglycerides in smooth muscle cells, as in fibroblasts, may be completely reversed in vitro. Lipids, 1976 Nov, 11(11), 791 - 7 Lipid accumulation cells derived from porcine aorta and grown under anaerobic conditions; Briggs RG et al.; Fibroblast-like cells, derived from porcine aorta, were cultured under aerobic and anaerobic conditions . Light and electron microscopic examinations, lipid composition measurements, and incorporation of radioactive precursors into lipids of these cells were performed . Anaerobically grown cells accumulated oil red O stainable droplets and within 6 hr the triacylglycerol content increased to 4 times the level determined in cells grown under aerobic conditions . This ratio remained constant throughout an additional 12 hr of growth . The fatty acid composition of the triacylglycerols which accumulated under anaerobic conditions differed from the composition of fatty acids in the triacylglycerols present in the growth medium . The cellular unesterified fatty acids of the anaerobically grown cells differed only slightly in composition from the fatty acids in the growth medium, while the unesterfied fatty acids of aerobically grown cells differed to a greater extent from those of the growth medium. Diabetes, 1976 Nov, 25(11), 1011 - 7 Growth hormone stimulating the growth of arterial medial cells in vitro . Absence of effect of insulin; Ledet T; Earlier studies have shown a stimulatory effect of diabetic serum on the growth of rabbit aortic medial cell cultures . Growth media supplemented with normal serum with added insulin (50-2,000 muU./ml . serum) did not enhance the growth of the medial cell cultures . Control media containing serum from recent diabetics with low insulin concentration stimulated the growth (2p less than 0.01) . Supplementation of normal serum with human growth hormone (final concentration 1-5 ng./ml . medium) resulted in a significant enhancement of growth (2p less than 0.005) . The growth-promoting effect of growth hormone was not detectable with lower concentrations (0.5 ng . and 0.1 ng./ml . medium) . The growth effect of the low concentration of growth hormone could not be augmented by increasing the concentration of glucose in the incubation medium . Growth hormone in an amount of 1 ng./ml . medium increased both the number of 3H-thymidine-labeled cells as identified by autoradiography and the number of mitotic bodies (2p less than 0.005 and 2 p less than 0.025) . The present results demonstrate that the growth-stimulating factor(s) in diabetic human serum described earlier is not insulin but may well be growth hormone. J Bacteriol, 1976 Nov, 128(2), 598 - 603 Regulation of hypoxanthine transport in Neurospora crassa; Sabina RL et al.; Hypoxanthine uptake and hypoxanthine phosphoribosyltransferase activity (EC 2.4.2.8) were determined in germinated conidia from the adenine auxotrophic strains ad-1 and ad-8 and the double mutant strain ad-1 ad-8 . The mutant strain ad-1 appears to lack aminoimidazolecarboximide ribonucleotide formyltransferase (EC 2.1.2.3) or inosine 5'monophosphate cyclohydrolase (EC 3.5.1.10) activities, or both, whereas the ad-8 strain lacks adenylosuccinate synthase activity (EC 6.3.4.4) . Normal (or wild-type) hypoxanthine transport capacity was found to the ad-1 conidia, whereas the ad-8 strains failed to take up any hypoxanthine . The double mutant strains showed intermediate transport capacities . Similar results were obtained for hypoxanthine phosphoribosyl-transferase activity assayed in germinated conidia . The ad-1 strain showed greatest activity, the ad-8 strain showed the least activity, and the double mutant strain showed intermediate activity levels . Ion-exchange chromatography of the growth media revealed that in the presence of NH+/4, the ad-8 strain excreted hypoxanthine or inosine, the ad-1 strain did not excrete any purines, and the ad-1 ad-8 double mutant strain excreted uric acid . In the absence of NH+/4, none of the strains excreted any detectable purine compounds. Mycopathologia, 1976 Oct 22, 59(3), 171 - 4 Effects of adenine and cytokinins on growth and protein kinase activity of Verticillium albo-atrum; Atmar VT et al.; Growth of Verticillium albo-atrum in liquid Czapek-Dox broth was stimulated about four-fold by added 10 mM adenine, N6-benzyladenine, or kinetin . Less stimulation was evident at lower concentrations . With none of these included in the basal growth medium, detectable protein kinase activity in cell-free extracts was low and responded minimally to cAMP (adenosine 3',5'-cyclic monophosphate) in the reaction mixture . With each of these compounds as an additive to the growth medium, protein kinase activity was not only greater but also responded markedly (several fold) to cAMP . These results demonstrate a strong correlation between exogenously supplied adenine and related compounds, increased growth, increased protein kinase activity, and kinase response to cAMP in this organism. Biochim Biophys Acta, 1976 Oct 21, 450(1), 21 - 32 The manipulation of the fatty acid composition of Dictyostelium discoideum and its effect on cell differentiation; Weeks G; The fatty acid composition of Dictyostelium discoideum has been modified by growing the axenic strain, Ax-2, in media conta-ning long chain polyenoic fatty acids . Large amounts of linoleic and linolenic acids are incorporated into the cellular lipids and further desaturated to two unusual fatty acids, 5,9,12-octadecatrienoic acid and 5,9,12,15-octadecatetraenoic acid, respectively . Arachidonic acid is also extensively incorporated but not further de;aturated . D . discoideum normally contains none of the above polyenoic fatty acids, and the amount incorporated depends upon the concentration of the fatty acid in the growth media . The cells containing large quantities of polyenoic fatty acid grow normally b,t exhibit impaired differentiation when removed from the growth medium . The incorporation of smaller quantities of the fatty acid has no adverse effect on differentiation . Cells grown in the presence of saturated or monoenoic fatty acids exhibit, at the most, only slight changes in the fatty acid composition of the cellular lipid and both grow and differentiate normally. Eur J Biochem, 1976 Oct 1, 69(1), 257 - 63 The uptake and metabolism of uridine by the slime mould Physarum polycephalum; Birch B et al.; 1 . Uridine is taken up by microplasmodia of Physarum polycephalum via a saturatable transport system with an apparent Km of 29 muM . An intracellular concentration significantly higher than that in the growth medium is attained, suggesting that the uptake is an active process . Both deoxyribonucleosides and ribonucleosides are competitive inhibitors of the uptake of uridine . 2 . In contrast, the rate of entry of uridine into surface plasmodia is a linear function of the concentration of the nucleoside in the growth medium, and the uptake is not inhibited by other nucleosides . 3 . As well as serving as a source of pyrimidine nucleotides for the synthesis of nucleic acids, uridine is also catabolised by P . polycephalum . Uracil accumulates in the growth medium and there is also significant conversion of C-2 of the pyrimidine ring to CO2 . The proportion of uridine subject to catabolism in surface plasmodia is less than that observed for microplasmodia. Steroids, 1976 Oct, 28(4), 535 - 48 15-Azasteroid blockage of cell permeability and mitochondrial respiration; Chesnut RW et al.; The 15-azasteroid, 1,10,11,11a-tetrahydro-11a-methyl-2H naphth (1,2-g)indol-7-o1, inhibits the growth of the cell culture lines KB and L-M as well as several strains of bacteria . The inhibition of growth is reversed following removal of the steroid from the growth medium . Using in vitro grown L-M cells, the compound inhibited the transport of amino acids and uracil . The action was non-detergent like and at least 100 times more effective in terminating metabolite transport than sodium azide . The azasteroid inhibited the oxidation of glutamate in isolated rat liver mitochondria . The oxidation of succinate was not effected by the azasteroid alone but in the presence of glutamate, the azasteroid uncoupled the oxidation of succinate from the ADP-ATP control . It is suggested that the azasteroid may be acting directly on the electron transport system and/or acting indirectly through membrane perturbations which disrupts the electron transport process. J Bacteriol, 1976 Oct, 128(1), 170 - 3 Biosynthesis of saturated and unsaturated fatty acids by a T-strain mycoplasma (Ureaplasma); Romano N et al.; A human T mycoplasma (Ureaplasma urealyticum) incorporated radioactivity into its lipids from {1-14C}acetate in the growth medium . Methanolysis of the lipids showed the label to be confined almost entirely to the methyl esters of the fatty acids . About 80% of the label was associated with the methyl esters of the saturated fatty acids, and the rest was found in the unsaturated methyl ester fraction . Gas-liquid chromatography of the saturated methyl esters showed the label to be present in the peaks of palmitate, myristate, and stearate, whereas in the unsaturated methyl ester fraction most of the radioactivity emerged in the peak of palmitoleate . The addition of either oleic or palmitic acid to the growth medium markedly decreased the organisms' incorporation of radioactivity from acetate . It is concluded that the T mycoplasma strain is capable of de novo synthesis of both saturated and unsaturated fatty acids, in this respect differing from all of the Mycoplasma and Acholeplasma strains investigated to date. Cell, 1976 Oct, 9(2), 205 - 11 Characterization of a cell culture model for the study of adenosine deaminase- and purine nucleoside phosphorylase-deficient immunologic disease; Ullman B et al.; The absence of erythrocytic adenosine deaminase (ADA) or purine nucleoside phosphorylase (PNP) has been associated with severe immunodeficiency disease in children . We have developed a cell culture model to study the possible relationships between purine salvage enzymes and immunologic function using an established T cell lymphosarcoma (S49) and a potent inhibitor of ADA, erythro-9(2-hydroxy-3-nonyl) adenine (EHNA) . Wild-type S49 cells are killed by dexamethasone or dbc AMP, and adenosine (5 muM) in the presence of an ADA inhibitor (6 muM EHNA) also prevents the growth of and kills these S49 cells . It has been proposed that adenosine is toxic to lymphoid cells by virtue of its ability to increase the intracellular concentrations of cyclic AMP . We examined the sensitivity of three mutants of S49 cells, with distinctive defects in some component of cyclic AMP metabolism or action, to killing by adenosine and EHNA . All three mutants are resistant to killing by isoproterenol or cholera toxin and two are resistant to dbc AMP itself, but all are sensitive to killing by adenosine and EHNA . Similarly, two dexamethasone-resistant S49 mutants are as sensitive to adenosine and EHNA as are the wildtype cells . We have also simulated the purine nucleoside phosphorylase deficiency in S49 cells by adding inosine and adenosine to the growth medium . In the presence of EHNA or inosine, the toxic effects of adenosine can be partially reversed by addition of (10-20 muM) uridine, an observation suggesting that adenosine is toxic as the result of its inducing pyrimidine starvation. Biochim Biophys Acta, 1976 Sep 24, 444(2), 539 - 53 Cyclic AMP and growth of Ehrlich ascites tumor cells . Lack of cyclic AMP elevation in nutritionally deprived cells and mechanism of retardation of growth by dibutryl cyclic AMP; Kaminskas E et al.; Cyclic AMP levels in Ehrlich ascites tumor cells changed little after deprivation of cells of essential nutrients, serum, glucose and amino acids, deprival of each of which leads to marked inhibition of growth and protein synthesis . Cyclic AMP levels also changed little after the addition of these nutrients to deprived cells . Thus cyclic AMP is not likely to be the intracellular mediator for growth regulation by these three nutrients . Elevation of cyclic AMP levels for short periods by exposure of cells to choleratoxin or theophylline produced only slight changes in parameters of protein synthesis (polyribosome pattern and rate of {3H}leucine incorporation) . An exposure for 1 day to dibutyryl cyclic AMP did not inhibit cell growth . However, prolonged exposure to dibutyryl cyclic AMP inhibited the multiplication of Ehrlich ascites cells both in suspension and in stationary cultures . No morphological effects were evident in the former; in the latter, cells attached firmly to the substratum and formed elongated cytoplasmic processes . Inhibition of cell multiplication by dibutyryl cyclic AMP was related to cell density and to serum concentration . Cells in dibutyryl cyclic AMP-containing media plated at low cell densities multiplied as rapidly as control cells . The final densities cells reached were determined by the serum concentration; in dibutyryl cyclic AMP-containing media these densities were about one-half those of respective control cells . Limitation of cell multiplication by dibutyryl cyclic AMP was reversed by the addition of serum, by resuspending cells at lower densities, or by resuspending cells in media without dibutyryl cyclic AMP . These findings suggested that dibutyryl cyclic AMP may affect the utilization of serum factors by cells . Dibutyryl cyclic AMP did not inactivate serum factors and did not change the rate at which cells depleted the growth medium of serum factors . Dibutyryl cyclic AMP may limit cell multiplication by increasing the cellular requirement for serum factors. Mol Gen Genet, 1976 Sep 23, 147(3), 251 - 62 Influence of cultural conditions and mutations on the composition of the outer membrane proteins of Escherichia coli; Lugtenberg B et al.; Various Escherichia coli strains differ in the composition of their major outer membrane proteins . However, all E . coli K12 strains tested possess the same major outer membrane proteins a, b, c and d, although quantitative differences were detected . The influence of growth conditions on the composition of the major outer membrane proteins of E . coli was analyzed . It was found that neither the growth phase at which the cells are harvested, nor the fatty acid composition of the phospholipids has a considerable influence on the composition of these proteins . However, the composition of the growth medium, and, to a less extent, the growth temperature, have a pronounced influence . Certain mutants, changed in the composition of their lipopolysaccharide, are deficient in protein b . Also mutants deficient in protein c and d respectively, are described . Proteins b and c of E . coli K12 were found to be associated with peptidoglycan . Protein bands, corresponding with flagellin and pilin respectively, were identified. Biochem J, 1976 Sep 15, 158(3), 567 - 73 The synthesis of glycosaminoglycans by cultures of rabbit corneal endothelial and stromal cells; Yue BY et al.; Confluent monolayer cultures of rabbit corneal endothelial and stromal cells were incubated independently with {35S}sulphate and {3H}glucosamine for 3 days . AFter incubation, labelled glycosaminoglycans were isolated from the growth medium and from a cellular fraction . These glycosaminoglycans were further characterized by DEAE-cellulose column chromatography and by sequential treatment with various glycosamino-glycan-degrading enzymes . Both endothelial and stromal cultures synthesized hyaluronic acid as the principal product . The cell fraction from the stromal cultures, however, had significantly less hyaluronic acid than that from the endothelial cultures . In addition, both types of cells synthesized a variety of sulphated glycosaminoglycans . The relative amounts of each sulphated glycosaminoglycan in the two cell lines were similar, with chondroitin 4-sulphate, chondroitin 6-sulphate and dermatan sulphate as the major components . Heparan sulphate was present in smaller amounts . Keratan sulphate was also identified, but only in very small amounts (1-3%) . The presence of dermatan sulphate and the high content of hyaluronic acid are similar to the pattern of glycosaminoglycans seen in regenerating or developing tissues, including cornea. Cancer Treat Rep, 1976 Sep, 60(9), 1363 - 7 Amino acid-conferred resistance to melphalan . I . Structure-activity relationship in cultured murine L1210 leukemia cells; Vistica DT et al.; Melphalan cytotoxicity to murine L1210 leukemia cells in culture was reduced in growth medium containing amino acids . Investigation of the effect of single amino acids revealed that the L-isomers of glutamine and leucine, but not the D-isomers, were the most active in decreasing cytotoxicity . Protection was concentration dependent, with maximum protection occurring at approximately 0.25 mM, a physiologic concentration . The LD90 for melphalan in the presence of 0.1 mM L-glutamine or L-leucine was increased by 7.3- and 10.8-fold respectively, under conditions where the cells had been pre-incubated with the amino acids . These results are interpreted to suggest that melphalan transport by the L1210 leukemia cell is mediated by a system also responsible for the transport of glutamine and leucine and that interaction with such a system may play a significant role in the chemotherapeutic activity of this alkylating agent. Arch Microbiol, 1976 Sep 1, 109(3), 227 - 35 Regulation of amino acid transport in growing cells of Streptomyces hydrogenans . I . Modulation of transport capacity and amino acid pool composition during the growth cycle; Langheinrich W et al.; (1) The active uptake of different amino acids by growing cells of Streptomyces hydrogenans was shown to be correlated with the physiological age of the cells . During the lag phase of growth the transport capacity increased and attained its highest level when the growth rate was maximum . During further growth the transport capacity declined progressively . The lowest transport activity was observed when the culture shifted into the stationary growth phase . (2) Such modulation of transport capacity was independent on the presence or absence of amino acids in the growth medium of the cells . (3) The size and the composition of the pool of free intracellular amino acids was also undergoing substantial variations during the growth cycle of the culture . In the lag phase, the levels of all amino acids decreased markedly and attained their lowest values at the end of this phase . During further growth the pool size was slowly replenished . (4) Removal of the pool resulted in a considerable gain of transport capacity . Therefore, it was concluded that active amino acid transport in growing Streptomyces hydrogenans is under feedback control by intracellular amino acids . (5) Quantitatively, the modulation of the pool size could not fully account for the variation of the transport capacity . Since a pool-independent stimulation of transport was found to be correlated with the increase of the growth rate of the cells, the possibility is discussed that the stimulation of transport is either due to increased levels of distinct RNA species, which might provide positive feedback signals for transport, or by increased rates of de novo synthesis of transport limiting proteins. J Cell Physiol, 1976 Sep, 89(1), 111 - 22 Density-dependent regulation of proliferation rate in cultured, androgen-responsive, tumour cells; ROBINSON JH et al.; Short-term cultures of androgen-responsive Shionogi 115 (S115) cells exhibited density-dependent regulation of proliferation rate in the presence or absence of testosterone . The average surface area per cell exposed to the growth medium was inversely proportional to population density . By contrast, long-term cultures (serially passaged in testosterone-containing medium for several months) did not exhibit density-dependent regulation of proliferation rate when grown in testosterone-containing medium . In this medium, cells became elongated and no longer exhibited any obvious decrease in exposed surface area with increasing density . Nevertheless, when subcultured into testosterone-free medium, these cells reverted to an epithelial morphology and exhibited density-dependent regulation of proliferation rate . These relationships suggested that the proliferation rate of cells decreased with density in proportion to the decrease in exposed surface area... Can J Microbiol, 1976 Sep, 22(9), 1282 - 92 The isolation and characterization of gliding motility mutants of Myxococcus xanthus; MacRae TH et al.; Nonmotile and motility-altered mutants of Myxococcus xanthus have been obtained by the use of chemical mutagens, ultraviolet irradiation, and a procedure for selective spontaneous mutants . As judged by their behaviour on a variety of growth media, in both plate and slide culture, the mutants were divided into four groups . One group contains mutants which are truly nonmotile . Myxococcus xanthus NM, previously described as a nonmotile mutant, may be similar to type 3 mutants (described in text). J Bacteriol, 1976 Sep, 127(3), 1370 - 5 Iron transport of Escherichia coli K-12: involvement of the colicin B receptor and of a citrate-inducible protein; Hancock RE et al.; It was shown that feuB mutants (defective in ferric enterochelin uptake) were unable to adsorb colicin B . In addition, they were missing one of the three outer-membrane proteins which are over produced in strains grown in iron-deficient, extracted medium . Thus this protein (the feuB protein) is probably the receptor for colicin B and functions in enterochelin-mediated iron transport . The feuB gene was located by P1 transduction at approximately 72.5 min on the Escherichia coli K-12 genetic map and thus maps separately from the other genes concerned with the enterochelin system . The outer membranes of various strains grown in the presence of 1 mM citrate contained a high level of a protein which was present in very small amounts when citrate was absent from the growth medium . This protein was most easily observed in feuB mutants grown in the presence of citrate, since on polyacrylamide gels it ran in a similar position to the feuB protein, which is missing in these mutants . The relationship of this citrate-inducible protein to the inducible citrate-dependent iron uptake system is discussed. J Bacteriol, 1976 Sep, 127(3), 1307 - 14 Role of deoxyribonucleic acid polymerase III in the repair of single-strand breaks produced in Escherichia coli deoxyribonucleic acid by gamma radiation; Hamelin C et al.; Cell survival, deoxyribonucleic acid (DNA) degradation, and the repair of DNA single-strand breaks were measured for Escherichia coli K-12 pol+, polA1, polC1026(ts), and polA1 polC1026(ts) cells after 137Cs gamma irradiation . The results indicate that DNA polymerase III is required for growth medium-dependent (type III) repair in polA+ or polA cells . In pol+ or polC cells, DNA polymerase I performs type II repair efficiently . The relative deficiencies of each of these strains in DNA repair generally correlate with their relative sensitivities to cell killing and with the extent of DNA degradation observed. Cancer Res, 1976 Sep, 36(9 pt.1), 3207 - 11 Inhibition of membrane transport of 5-fluoro{6-3H}deoxyuridine into L5178Y mouse leukemia cells; Wigler PW et al.; The influx of 1.0 muM 5-fluoro{6-3H}deoxyuridine (5F{6-3H}dUrd) into L5178Y mouse leukemia cells followed a linear function with time from 2 to 10 min . Ammonium 5-bromodeoxyuridine 5'-methylphosphonate (BrdUrd-OPO2Me) inhibited the membrane transport of 5F{6-3H}dUrd into L5178Y cells . Influx of 5F{6-3H}dUrd into inhibited cells was observed from zero to 3 min; after 3 min the net rate of 5F{6-3H}dUrd uptake into the cells treated with 18 muM BrdUrd-OPO2Me was almost zero . The cellular uptake of 2'-deoxy{6-3H}uridine or 5-bromo{6-3H}deoxyuridine was inhibited by BrdUrd-OPO2Me . The L5178Y cells were grown for 96 hr in a medium that contained tritium-labeled BruDur-OPO2Me . An analysis of the labeled products in the growth medium showed that the ester linkage is not cleaved to separate the {3H}methylphosphonate group and the nucleoside moiety of BrdUrd-OPO2{3H}Me . The activity of thymidine kinase in a cell-free preparation from L5178Y cells was demonstrated . Although 37 muM 5-bromo-2'deoxyuridine produced an inhibition of approximately 45% in kinase activity, BrdUrd-OPO2Me had no effect on enzyme activity . The results indicate that BrdUrd-OPO2Me is an inhibitor of the cell membrane transport of the 5-fluoro and 5-bromo derivatives of 2'-deoxy{6-3H}uridine. Can J Microbiol, 1976 Sep, 22(9), 1300 - 6 Production of volatiles from decomposing plant tissues and effect of these volatiles on Rhizoctonia solani in culture; Lewis JA; Volatiles, of which NH3 is a major component, were evolved from decomposing immature corn tissue (c:n9) and affected R . solani in culture two ways: they supplied additional nitrogen to the growth medium so that fungal mycelial growth increased; and they raised substrate pH from 5.5 to 8.2 which induced melanization of mycelium . Volatiles increased fungus growth and pigmentation within 2 weeks of amendment addition to soil . Increases were concomitant with NH3 production from corn tissue . More NH3 evolved from decomposing corn tissues of C:N9 and 17 than from those of C-N 33 and 81 . More growth and pigmentation occurred in flasks through which volatiles from decomposing corn (C:N9) were passed than in flasks through which volatiles from nonamended soil or decomposing corn (C:N81) were passed . Carbon dioxide from decomposing tissues did not affect growth or pigmentation . Twice as much NH3 evolved from corn tissue (C:N9) which decomposed in saturated soil than from tissue which decomposed in soil at 50% of its water-holding capacity . Pigment production doubled under saturated conditions. Can J Microbiol, 1976 Sep, 22(9), 1233 - 44 Dependence of the superficial layers of Spirillum putridiconchylium on Ca2+ or Sr2+; Beveridge TJ et al.; Chelating agents disrupted the superficial layers on Spirillum putridiconchylium and adsorption of cationized ferritin indicated that both upper and lower surfaces of superficial layer fragments, as well as the outer membrane surface, possessed areas which were negatively charged . Growth of the bacterium in 1% casamino acids (vitamin free) resulted in cells which were devoid of the superficial layers, and negative staining of these cells revealed in amorphous precipitate together with a vesicular outer membrane component extruding from their surfaces into the medium . Addition of either 1 mM Ca2+ or 1 mM Sr2+ to the growth medium produced the typical regularly structured cell surface, whereas addition of equal concentrations of Li+, Na+, K+, Mg2+, Ba2+, Mn2+, Fe3+, or three polyamines produced the structureless surface. Biochem J, 1976 Aug 15, 158(2), 235 - 41 Polyamine and ornithine metabolism during the germination of conidia of Aspergillus nidulans; Stevens L et al.; 1 . The activities of ornithine decarboxylase, S-adenosylmethionine decarboxylase and ornithine-2-oxoglutarate aminotransf