Identification d'une nucléotide pyrophosphatase exocellulaire dans le milieu de culture de Streptomyces mediterranei ME/R 17

1979 ◽  
Vol 25 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Gérard Pellon ◽  
Georges Michel
Keyword(s):  
Enzyme Preparation ◽  
Culture Medium ◽  
Deae Cellulose ◽  
Growth Cycle ◽  
Exponential Phase ◽  
Nucleotidase Activity ◽  
Late Exponential Phase ◽  
Nucleotide Pyrophosphatase ◽  
Pyrophosphatase Activity ◽  
Positive Effect

An exocellular pyrophosphatase, active on the nucleotide precursors of peptidoglycans, has been found in the culture medium of Streptomyces mediterranei ME/R 17. This enzyme was separated from the DD-carboxypeptidase by batchwise adsorption on DEAE cellulose. The pyrophosphatase had no strict substrate requirements, it hydrolyzed various UDP-sugar substrates: UDP-GlcNAc. UDP-MurNAc and UDP-MurNAc peptides, giving rise to the corresponding sugar phosphate and to UMP. The enzyme preparation also contained a 5′-nucleotidase activity and UMP was further split to give uridine. This nucleotidase activity was inhibited by potassium tetraborate. Both cytoplasmic and particulate preparations from cells of S. mediterranei also contained a pyrophosphatase activity while only the particulate fractions showed the DD-carboxypeptidase activity.The pyrophosphatase excretion was tested during the growth cycle. The activity of the enzyme showed a constant increase throughout the exponential growth and a stronger increase in the late exponential phase. Such a result could be correlated with a consumption of the nutrients in the culture medium, in fact a relatively poor culture medium had a strong positive effect upon the production of the exocellular pyrophosphatase.

scholarly journals The mannophosphoinositides of Corynebacterium aquaticum

1975 ◽  
Vol 148 (2) ◽  
pp. 253-258 ◽  
Author(s):  
J A Hackett ◽  
P J Brennan
Keyword(s):  
Stationary Phase ◽  
Exponential Growth ◽  
Growth Cycle ◽  
Exponential Phase ◽  
Late Stationary Phase ◽  
Late Exponential Phase

Besides the monomannophosphoinositide previously reported in Corynebacterium aquaticum small amounts of other, apparently more glycosylated, mannophosphoinositides have been identified in stationary phase cells. Moreover, by labelling cells with [32P]Pi, phosphatidylinositol was found, comprising about 1.5% of the stationary-phase phospholipids. 2. Pulse-chase experiments performed on cells in the late exponential phase of growth further suggested the sequence phosphatidylinositol leads to monomannophosphoinositide as the first step in the biosynthesis of the mannophosphoinositides. 3. Di-and tri-mannophosphoinositides are apparently the main mannophosphoinositides present during exponential growth. Monomannophosphoinositide predominates only in late stationary phase; in the earlier stationary phase, phosphatidylinositol comprises 50% of the phosphoinositide lipid, and tetramannophosphoinositide constitutes much of the remainder. 4. The metabolism and functions of the mannophosphoinositides are discussed, particularly in relation to changes in their composition throughout the growth cycle.

Measurement of Primary Productivity in Dense Algal Cultures

1983 ◽  
Vol 40 (6) ◽  
pp. 807-810 ◽  
Author(s):  
S-R. Gentner
Keyword(s):  
Primary Productivity ◽  
Growth Cycle ◽  
Exponential Phase ◽  
Scintillation Counting ◽  
Late Exponential Phase ◽  
Limited Sample ◽  
Productivity Measurement ◽  
Limited Sample Size ◽  
Scenedesmus Acutus ◽  
Algal Cultures

The 14C-bicarbonate method of primary productivity measurement was modified for dense algal cultures by the addition of NaHCO3 to avoid exhaustion of carbon source. Using this method plus a modified procedure for scintillation counting of limited sample size, six species of chlorophyean algae were studied daily throughout the growth cycle. Scenedesmus acutus was the most productive with a peak productivity of 5.3 mg C∙L−1∙h−1 at 9.7 × 103 lx during late exponential phase. Peak productivity values (mg C∙L−1∙h−1) for the other species were 2 for Chlorella vulgaris, 2.3 for Ankistrodesmus braunii, and 3.4, 3.5, and 3.6 mg C∙L−1∙h−1 for Scenedesmus basiliensis, S. bijugatus, and S. parisiensis, respectively.

scholarly journals Purification and subunit structure of argininosuccinate lyase from Chlamydomonas reinhardi

1977 ◽  
Vol 167 (1) ◽  
pp. 71-75 ◽  
Author(s):  
R F Matagne ◽  
J P Schlösser
Keyword(s):  
Enzyme Activity ◽  
Crude Extract ◽  
Enzyme Preparation ◽  
Sodium Dodecyl ◽  
Gel Filtration ◽  
Deae Cellulose ◽  
Activity Analysis ◽  
Disc Electrophoresis ◽  
Subunit Structure ◽  
Argininosuccinate Lyase

Argininosuccinate lyase (EC 4.3.2.1) was purified by (NH4)2SO4 fractionation, chromatography on DEAE-cellulose and gel filtration on Sephadex G-200. The final enzyme preparation was purified 46-fold compared with the crude extract. Electrophoresis of this preparation revealed three bands, the major one having the enzyme activity. Analysis of the enzyme by gel filtration and by disc electrophoresis (in two different concentrations of acrylamide) gave mol.wts. of 200000 (+/- 15000) and 190000 (+/- 20000) respectively. Treatment with sodium dodecyl sulphate and mercaptoethanol dissociated the enzyme into subunits of mol.wt. 39000 (+/-2000). The results are indicative of the multimeric structure of the enzyme, which is composed of five (perhaps four or six) identical subunits.

Response of Liverwort Cells to Peroxidizing Herbicides

1992 ◽  
Vol 47 (5-6) ◽  
pp. 394-399
Author(s):  
Shuji Iwata ◽  
Naoko Nakayama ◽  
Shunji Nakagawara ◽  
Yoshimoto Ohta ◽  
Takaharu Tanaka ◽  
...  
Keyword(s):  
Cell Growth ◽  
Oxidative Damage ◽  
Early Treatment ◽  
Protoporphyrin Ix ◽  
Cell Suspension Cultures ◽  
Exponential Phase ◽  
Marchantia Polymorpha ◽  
Late Exponential Phase ◽  
Kinetics Of

Cell suspension cultures of the liverwort, Marchantia polymorpha L. were found useful to study the influence of peroxidizing herbicides either on the greening process or on the fully green cells. The cells of both physiological stages exhibit a characteristic sensitivity to the herbicides. The sensitivity increased rapidly during the exponential phase of growth, reached a maximum during the late exponential phase, and then decreased in the stationary phase. We investigated the kinetics of accumulation of protoporphyrin IX (PPIX) in Marchantia cells treated with several peroxidizing herbicides at various stages of cell growth, and observed a correlation between accumulation of PPIX and herbicidal damage. The glutathione (GSH) content in the cell was also investigated to examine the role of GSH against herbicide treatment. In the light, GSH levels in the cells treated with AFM rose rapidly reaching a peak after 8 h, and rapidly decreased subsequently. The beginning of PPIX accumulation coincided with the decline of GSH after 8 h of treatment. Obviously, GSH plays a key role in protection against oxidative damage caused by AFM in the early treatment period. In the dark, AFM also induced an accumulation of GSH and PPIX, followed by a decline in GSH and PPIX contents during a 20 h incubation. The decline of PPIX was observed several hours after GSH starts to decrease, remaining at a constant level for the following 40 h, leading to accumulation of an other fluorescent still-unknown pigment.

scholarly journals The effect of inhibitors on the oxygen kinetics of terminal oxidases of Acanthamoeba castellanii

1979 ◽  
Vol 182 (1) ◽  
pp. 11-15 ◽  
Author(s):  
D Lloyd ◽  
S Edwards ◽  
B Kristensen ◽  
H Degn
Keyword(s):  
Competitive Inhibition ◽  
Acanthamoeba Castellanii ◽  
Exponential Phase ◽  
Oxygen Utilization ◽  
Late Exponential Phase ◽  
Salicylhydroxamic Acid ◽  
Terminal Oxidases ◽  
Low Concentrations ◽  
Transport Chain ◽  
Oxygen Sensitive

1. Respiration of growing cultures of Acanthamoeba castellanii is inhibited less than 60% by azide (35 mM); the respiration of early-exponential-phase cultures differs from that of late-exponential-phase cultures in being stimulated by up to 120% by low concentrations (less than 1 mM) of this inhibitor. Azide (0.5 mM) plus 1 mM-salicylhydroxamic acid gives 80% inhibition of respiration in early- or late-exponential-phase cultures. 2. Lineweaver-Burk plots of 1/v against 1/[O2] for growing and stationary-phase cultures give values of less than 1 muM for the apparent Km for oxygen. 3. These values are not significantly altered when determined in the presence of 1 mM-salicylhydroxamic acid. 4. Higher values (greater than 7 muM) for apparent Km values for oxygen were obtained in the presence of azide, which gives non-linear Lineweaver-Burk plots. 5. Competitive inhibition of respiration by CO occurs with Ki 2.4 muM. 6. The results are discussed in terms of the presence of three terminal oxidases in this organism, namely two oxidases with high affinities for oxygen (cytochrome c oxidase of the main phosphorylating electron-transport chain and the salicylhydroxamic acid-sensitive oxidase) and a third oxidase with a low affinity for oxygen, sensitive to inhibition by cyanide but not by azide or salicylhydroxamic acid. The relative contributions to oxygen utilization by these oxidases change during the growth of a batch culture.

Regulation of expression of the cyanide-insensitive terminal oxidase in Pseudomonas aeruginosa

Microbiology ◽  
2003 ◽  
Vol 149 (5) ◽  
pp. 1275-1284 ◽  
Author(s):  
Megan Cooper ◽  
Gholam Reza Tavankar ◽  
Huw D. Williams
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Stationary Phase ◽  
Culture Medium ◽  
Homoserine Lactone ◽  
Exponential Phase ◽  
Terminal Oxidase ◽  
Regulation Of Expression ◽  
Potent Inducer ◽  
Protein Levels ◽  
In The Wild

The regulation of the cyanide-insensitive oxidase (CIO) in Pseudomonas aeruginosa, a bacterium that can synthesize HCN, is reported. The expression of a cioA–lacZ transcriptional fusion, CioA protein levels and CIO activity were low in exponential phase but induced about fivefold upon entry into stationary phase. Varying the O2 transfer coefficient from 11·5 h−1 to 87·4 h−1 had no effect on CIO expression and no correlation was observed between CIO induction and the dissolved O2 levels in the growth medium. However, a mutant deleted for the O2-sensitive transcriptional regulator ANR derepressed CIO expression in an O2-sensitive manner, with the highest induction occurring under low-O2 conditions. Therefore, CIO expression can respond to a signal generated by low O2 levels, but this response is normally kept in check by ANR repression. ANR may play an important role in preventing overexpression of the CIO in relation to other terminal oxidases. A component present in spent culture medium was able to induce CIO expression. However, experiments with purified N-butanoyl-l-homoserine lactone or N-(3-oxododecanoyl)homoserine lactone ruled out a role for these quorum-sensing molecules in the control of CIO expression. Cyanide was a potent inducer of the CIO at physiologically relevant concentrations and experiments using spent culture medium from a ΔhcnB mutant, which is unable to synthesize cyanide, showed that cyanide was the inducing factor present in P. aeruginosa spent culture medium. However, the finding that in a ΔhcnB mutant cioA–lacZ expression was induced normally upon entry into stationary phase indicated that cyanide was not the endogenous inducer of the terminal oxidase. The authors suggest that the failure of O2 to have an effect on CIO expression in the wild-type can be explained either by the requirement for an additional, stationary-phase-specific inducing signal or by the loss of an exponential-phase-specific repressing signal.

scholarly journals Treatment of HL-60 cells with dimethyl sulphoxide inhibits the formation of β-N-acetylhexosaminidase S

1990 ◽  
Vol 272 (1) ◽  
pp. 211-215 ◽  
Author(s):  
C Emiliani ◽  
F Falzetti ◽  
A Orlacchio ◽  
J L Stirling
Keyword(s):  
Specific Activity ◽  
Deae Cellulose ◽  
Normal Growth ◽  
Growth Cycle ◽  
Dimethyl Sulphoxide ◽  
Developmental Changes ◽  
Beta Subunits ◽  
Induction Of Differentiation ◽  
Low Cell Density ◽  
Beta Galactosidase

beta-N-Acetylhexosaminidase of HL-60 cells was separated into two main forms, A and S, by chromatography on DEAE-cellulose. Analysis of developmental changes in the isoenzyme pattern was complicated by the fact that the specific activity of beta-N-acetylhexosaminidase underwent a 6-fold change during the normal growth cycle. Two other lysosomal enzymes, beta-galactosidase and alpha-mannosidase, behaved similarly. Induction of differentiation of HL-60 cells with dimethyl sulphoxide at a low cell density (3 x 10(5) cells/ml) had a greater effect on the abundance of alpha-subunits of beta-N-acetylhexosaminidase, measured with 4-methylumbelliferyl-beta-N-acetylglucosaminide 6-sulphate, than of beta-subunits, measured with 4-methylumbelliferyl-beta-N-acetylglucosamine, and resulted in an isoenzyme profile in which A and B were the major forms, with the levels of form S greatly decreased.

Rajeunissement de clones matures d'Hevea brasiliensis (Müll. Arg.) par microgreffage in vitro

1994 ◽  
Vol 74 (3) ◽  
pp. 623-630 ◽  
Author(s):  
Y. Perrin ◽  
L. Lardet ◽  
F. Enjalric ◽  
M. P. Carron
Keyword(s):  
Key Words ◽  
Hevea Brasiliensis ◽  
Culture Medium ◽  
Shoot Elongation ◽  
Nodal Explants ◽  
Axillary Shoots ◽  
Juvenile Material ◽  
In Vitro Micrografting ◽  
Positive Effect

In vitro micrografting of apices of two mature genotypes of Hevea brasiliensis (Müll. Arg.), IRCA 18 and PB 235, on 3-wk-old seedlings grown in vitro permitted successfull in vitro micro-cutting of these two genotypes. Microcutting of micrografted material was impossible from nodal explants or shoot tips of scions developed in vitro on rootstocks. Such explants were incapable of caulogenesis activity after their isolation. This problem was resolved using mixed explants, each consisting of a part of the rootstock in contact with the culture medium, and of the clonal scion from which axillary shoots are developed regularly along the subcultures. Budding and shoot elongation abilities along the subcultures have been compared between mixed explants from micrografts, nodal explants from juvenile material and nodal explants from non-micrografted mature genotypes. The results show a very positive effect of micrografting on the in vitro caulogenesis ability in both genotypes. Moreover, shoots produced by mixed explants from micrografts exhibit the same rooting ability as shoots produced by explants collected on juvenile material. Key words: Rejuvenation, Hevea brasiliensis, in vitro micrografting, micropropagation, in vitro microcutting

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