SYNTHESIS OF MACROMOLECULES IN MAIZE ROOT TIPS

1967 ◽  
Vol 45 (4) ◽  
pp. 385-394 ◽  
Author(s):  
Ann Oaks
Keyword(s):  
Amino Acids ◽  
Cell Wall ◽  
Continuous Flow ◽  
Flow System ◽  
Dry Weight ◽  
Maximal Rate ◽  
Root Tips ◽  
Corn Roots ◽  
Rate Of Increase ◽  
Cell Wall Carbohydrates

Corn roots grown in a glucose–salts medium in a continuous flow system suffered an initial loss of protein before an increase was observed. A maximal rate of increase in cell-wall carbohydrates was achieved after 20 hours in culture. There was some loss in RNA while the increase in DNA was slight. A synthetic mixture of 15 L-amino acids enhanced the growth (defined as increase in length, dry weight, or alcohol-insoluble nitrogen) of glucose-grown roots. With this enriched medium there was a slight increase of protein over the initial 20-hour period and a faster rate of increase after this time. No lag in the increase in cell-wall carbohydrates was observed. Despite these symptoms of better growth the level of DNA was not improved by the addition of the amino acids and the RNA content was actually lower than in the glucose-grown roots. Although the level of RNA was less in cultured than in normal roots, ribosomal and soluble RNA accounted for similar proportions of the total RNA in each case.

Nutritional requirements for cell wall synthesis in Micrococcus lysodeikticus

1969 ◽  
Vol 15 (4) ◽  
pp. 327-334
Author(s):  
M. P. Hatton
Keyword(s):  
Amino Acids ◽  
Cell Wall ◽  
Glutamic Acid ◽  
Dry Weight ◽  
Defined Medium ◽  
Complete Medium ◽  
Magnesium Ions ◽  
Cell Wall Synthesis ◽  
Micrococcus Lysodeikticus ◽  
Total Dry Weight

Preferential cell wall synthesis in Micrococcus lysodeikticus, as determined by an increase in the dry weight of the cell wall, took place in a medium containing DL-glutamic acid, DL-alanine, L-lysine, glycine, magnesium ions, glucose and phosphate buffer, pH 7.0. Cell wall synthesis could not be completely dissociated from protein synthesis in the 'cell wall' medium. The cell wall synthesized in the defined medium accounted for 40–56% of the total dry weight increase of the cells. Chloramphenicol had no effect on cell wall synthesis. Incorporation of uracil and guanine in the medium did not result in any increase in the amount of cell wall synthesized. DL-Glutamic acid alone, or a mixture of the three amino acids DL-alanine, L-lysine, and glycine, were capable of replacing the four amino acids present in the complete medium, but under these conditions the total dry weight of cell wall synthesized was only 75% of that produced in the complete medium. There was no reduction in cell wall synthesis when L-glutamic acid replaced DL-glutamic acid, L-alanine replaced DL-alanine, or sucrose replaced glucose in the cell wall medium. Deprivation of magnesium ions produced the greatest decrease in wall synthesis; this was the most important single factor involved in cell wall synthesis which was studied in the present investigation. There was no observable change in the chemical composition of the cell wall synthesized in the 'wall' medium when compared to that synthesized by cells grown in a complex medium.

scholarly journals A Semi-Automated Bone Pretreatment System and the Pretreatment of Older and Contaminated Samples

Radiocarbon ◽  
1989 ◽  
Vol 31 (03) ◽  
pp. 247-253 ◽  
Author(s):  
I A Law ◽  
R E M Hedges
Keyword(s):  
Amino Acids ◽  
Cation Exchange ◽  
Continuous Flow ◽  
Exchange Resin ◽  
Flow System ◽  
Cation Exchange Resin ◽  
Flow Cells ◽  
Continuous Flow System ◽  
New Process ◽  
Degree Of Purification

A semi-automated continuous-flow system used to process archaeological bone to purified gelatin or amino acids for 14C dating is described. Powdered bone is retained in flow cells specifically designed to permit the sequential leaching of the bone with acid, alkali and water. Crude collagen obtained by this process is gelatinized, and than either purified directly using a macroporous cation exchange resin (BioRad AGMP-50), or hydrolyzed and the amino acids desalted on BioRad 50W-X8 resin. When compared with previous methods used by the laboratory, the new method allows more samples to be treated to a higher degree of purification. Examples of dates obtained on “standard” bones are presented, and confirm that no contamination is introduced from the components used in the new process.

Composition and properties of the cell wall of Methanospirillum hungatii

1980 ◽  
Vol 26 (2) ◽  
pp. 115-120 ◽  
Author(s):  
G. D. Sprott ◽  
R. C. McKellar
Keyword(s):  
Amino Acids ◽  
Cell Wall ◽  
Cell Walls ◽  
Weight Fraction ◽  
Dry Weight ◽  
Wall Material ◽  
Bond Breaking ◽  
High Molecular Weight Fraction ◽  
Cell Wall Proteins ◽  
Isolated Cell

Dithiothreitol reacted, at pH 9.0, with the isolated cell walls of Methanospirillum hungatii, to release about 23% of the cell wall dry weight as a high molecular weight fraction (> 0.5 million daltons). Untreated walls consisted of 70% amino acids, 11% lipid, and 6.6% carbohydrate. Sugars were identified as rhamnose, ribose, glucose, galactose, and mannose. The wall material that was released contained only 47% amino acids and was enriched in lipid, glucose, and phosphate. These results support data from electron micrographs, showing the localized release of cell wall material by the disulfide bond-breaking reagent at alkaline pH. In amino acid composition the untreated walls did not differ greatly from the material released by dithiothreitol, but differed considerably from the walls of another strain of M. hungatii. The ratios of the amino acids found in the cell wall proteins of several archaebacteria and of Bacillus cereus spore coats were similar.

scholarly journals RESPONSE OF `ALASKA' PEA SEEDLINGS TO FREEZING AND CHILLING STRESSES AFTER EXOGENOUS APPLICATION OF ABSCISIC ACID.

HortScience ◽  
1991 ◽  
Vol 26 (6) ◽  
pp. 737B-737
Author(s):  
Milton E. Tignor ◽  
Russell L. Weiser
Keyword(s):  
Amino Acids ◽  
Cell Wall ◽  
Abscisic Acid ◽  
Chilling Stress ◽  
Dry Weight ◽  
Visual Observation ◽  
Distilled Water ◽  
Fresh Weight ◽  
Pea Seedlings ◽  
Blank Solution

Alaska peas (Pisum sativum `Alaska') germinated in a dark growth chamber were treated ABA dissolved in a small amount of acetone before diluting in distilled water with 0.1% spreader. A blank solution was identically prepared without ABA. Both solutions were applied via paintbrush to the epicotyls of the peas every twelve hours for seven days following emergence. The blank solution was applied to two controls, chronological and physiological. A methanol bath was used to induce freezing and chilling stresses. ABA significantly improved cold tolerance (electrolyte leakage) in the pea seedlings for both freezing and chilling stress as compared to the physiological and chronological controls. Visual observation of the pea stems suggested a difference in stem flexibility among ABA treated peas and the controls. Pea stem elasticity and plasticity were measured along with plant dry weight, cell wall weight/gram fresh weight, and the quantity of cell wall sugars and amino acids.

An analysis of the metabolism and cell wall composition of Candida albicans during germ-tube formation

1983 ◽  
Vol 29 (11) ◽  
pp. 1514-1525 ◽  
Author(s):  
Patrick A. Sullivan ◽  
Chiew Yoke Yin ◽  
Christopher Molloy ◽  
Matthew D. Templeton ◽  
Maxwell G. Shepherd
Keyword(s):  
Amino Acids ◽  
Cell Wall ◽  
Germ Tube ◽  
Dry Weight ◽  
Tube Formation ◽  
Cell Wall Composition ◽  
Yeast Cells ◽  
Tube Forming ◽  
Insoluble Glucan ◽  
Germ Tubes

The uptake of nutrients (glucose, glutamine, and N-acetylglucosamine), the intracellular concentrations of metabolites (glucose-6-phosphate, cyclic AMP, amino acids, trehalose, and glycogen) and cell wall composition were studied in Candida albicans. These analyses were carried out with exponential-phase, stationary-phase, and starved yeast cells, and during germ-tube formation. Germ tubes formed during a 3-h incubation of starved yeast cells (0.8 × 108 cells/mL) at 37 °C during which time the nutrients glucose plus glutamine or N-acetylglucosamine (2.5 mM of each) were completely utilized. Control incubations with these nutrients at 28 °C did not form germ tubes. Uptake of N-acetylglucosamine and glutamine was inhibited by cycloheximide which suggests that de novo protein synthesis was required for the induction of these uptake systems. The glucose-6-phosphate content varied from 0.4 nmol/mg dry weight for starved cells to 2–3 nmol/mg dry weight for growing yeast cells and germ tube forming cells. Trehalose content varied from 85 nmol/mg dry weight (growing yeast cells and germ tube forming cells) to 165 nmol/mg weight (stationary-phase cells). The glycogen content decreased during germ-tube formation (from 800 to 600 nmol glucose equivalent/mg dry weight) but increased (to 1000 nmol glucose equivalent/mg dry weight) in the control incubation of yeast cells. Cyclic AMP remained constant throughout germ-tube formation at 4–6 pmol/mg dry weight. The total amino acid pool was similar in exponential, starved, and germ tube forming cells but there were changes in the amounts of individual amino acids. The overall cell wall composition of yeast cells and germ tube forming cells were similar: lipid (2%, w/w); protein (3–6%), and carbohydrate (77–85%). The total carbohydrates were accounted for as the following fractions: alkali-soluble glucan (3–8%), mannan (20–23%), acid-soluble glucan (24–27%), and acid-insoluble glucan (18–26%). The relative amounts of the alkali-soluble and insoluble glucan changed during starvation of yeast cells, reinitiation of yeast-phase growth, and germ-tube formation. Analysis of the insoluble glucan fraction from cells labelled with [14C]glucose during germ-tube formation showed that the chitin content of the cell wall increased from 0.6% to 2.7% (w/w).

Nutrient uptake byCandida albicans: the influence of cell surface mannoproteins

1999 ◽  
Vol 45 (5) ◽  
pp. 353-359 ◽  
Author(s):  
Phyllis C Braun
Keyword(s):  
Amino Acids ◽  
Cell Wall ◽  
Candida Albicans ◽  
Aspartic Acid ◽  
Intracellular Transport ◽  
Strain Differences ◽  
Dry Weight ◽  
Culture Conditions ◽  
Wall Structure ◽  
Biochemical Analyses

Numerous ultrastructural and biochemical analyses have been performed to characterize the cell wall composition and structure of Candida albicans. However, little investigation has focused on how subtle differences in cell wall structure influence the intracellular transport of amino acids and monosaccharides. In this study C. albicans 4918 and ATCC 10231 were grown in culture conditions capable of modifying surface mannoproteins and induced surface hydrophobic or hydrophilic yeast cell wall states. Subcultures of these hydrophobic and hydrophilic yeasts were subsequently incubated with one of seven L-[3H] amino acids: glycine, leucine, proline, serine, aspartic acid, lysine, or arginine. The transport of [3H] mannose and [3H] N-acetyl-D-glucosamine were also investigated. This study revealed significant strain differences (P [Formula: see text] 0.05) between hydrophilic and hydrophobic yeast transport of these nutrients throughout a 2 h incubation. Hydrophilic cultures of 4918 and ATCC 10231 transported nearly two times more (pmol mg-1dry weight) proline, mannose, and N-acetyl-D-glucosamine than hydrophobic yeast. Hydrophobic cultures preferentially incorporated serine and aspartic acid in both these strains. Strain variation was indicated with the transport of leucine, lysine, and arginine, as follows: experiments showed that hydrophilic 4918 cultures selectively transported leucine, lysine, and arginine, whereas, the hydrophobic ATCC 10231 cultures incorporated these amino acids.Key words: Candida albicans, mannoproteins, amino acid transport.

Nitrification and Autotrophic Denitrification in Calcium Alginate Beads

1987 ◽  
Vol 19 (1-2) ◽  
pp. 175-182 ◽  
Author(s):  
Z. Lewandowski ◽  
R. Bakke ◽  
W. G. Characklis
Keyword(s):  
Calcium Carbonate ◽  
Calcium Ions ◽  
Continuous Flow ◽  
Calcium Alginate ◽  
Microbial Respiration ◽  
Flow System ◽  
Alginate Beads ◽  
Alginate Gel ◽  
Gel Beads ◽  
Calcium Alginate Gel

Immobilization of nitrifiers and autotrophic denitrifiers (Thiobacillus denitrificans) within calcium alginate gel was demonstrated. Calcium carbonate reagent was immobilized along with bacteria as the stabilizing agent. Protons released as a result of microbial respiration reacted with calcium carbonate producing calcium ions which internally stabilized the calcium alginate gel. The microbially active gel beads were mechanically stable and active for three months in a continuous flow system without addition of calcium.

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