scholarly journals VITAMIN B12 AND THE MACROMOLECULAR COMPOSITION OF EUGLENA

1970 ◽  
Vol 47 (2) ◽  
pp. 525-530 ◽  
Author(s):  
Edgar F. Carell ◽  
Pamela Leban Johnston ◽  
Alan R. Christopher
Keyword(s):  
Vitamin B12 ◽  
Macromolecular Composition

scholarly journals VITAMIN B12 AND THE MACROMOLECULAR COMPOSITION OF EUGLENA

1973 ◽  
Vol 57 (3) ◽  
pp. 668-674 ◽  
Author(s):  
Pamela Leban Johnston ◽  
Edgar F. Carell
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Dna Synthesis ◽  
Vitamin B12 ◽  
Protein Content ◽  
Euglena Gracilis ◽  
Cell Divisions ◽  
Synchronous Cell ◽  
A Minor ◽  
Macromolecular Composition

When vitamin B12 is added to B12-deficient cultures of Euglena gracilis, the cells undergo two relatively synchronous cell divisions within a shorter than usual period of time, apparently as a result of a transitory shortening of the cell cycle. The first cell division pulse, occurring 4.5 h after addition of B12, is preceded by the completion of DNA duplication, but appears to involve no net synthesis of RNA or protein. Before the second round of cell division at about 11 h, a significant amount of DNA synthesis is observed. This time it is accompanied by a minor increase in the RNA and protein content of the culture. The cellular contents of RNA and protein were observed to decrease steadily after the resumption of cell division in B12-depleted cultures receiving the vitamin. Ultimately all three macromolecules returned to their nondeficient, plateau stage levels; by this time, cell division had ceased.

Vitamin B12 and the macromolecular composition of Euglena

1974 ◽  
Vol 89 (1) ◽  
pp. 71-78 ◽  
Author(s):  
A.R. Christopher ◽  
K. Dobrosielski-Vergona ◽  
G. Goetz ◽  
P.L. Johnston ◽  
E.F. Carell
Keyword(s):  
Vitamin B12 ◽  
Macromolecular Composition

scholarly journals VITAMIN B12 AND THE MACROMOLECULAR COMPOSITION OF EUGLENA

1974 ◽  
Vol 62 (3) ◽  
pp. 672-678 ◽  
Author(s):  
George H. Goetz ◽  
Pamela L. Johnston ◽  
Kathy Dobrosielski-Vergona ◽  
Edgar F. Carell
Keyword(s):  
Protein Synthesis ◽  
Cell Division ◽  
Dna Synthesis ◽  
Vitamin B12 ◽  
Cellular Protein ◽  
Initial Increase ◽  
Leucine Incorporation ◽  
Total Cellular Protein ◽  
Macromolecular Composition ◽  
New Protein

When cycloheximide is added to (B12)-deficient cultures before or after replenishment of the cells with B12, reversion of these cells is inhibited. This inhibition is not caused by interference of the inhibitor in the uptake of B12 as measured by division kinetics. Cycloheximide does not inhibit the initial increase in the rate of DNA synthesis caused by B12 replenishment, but within 30–45 min the rate decreases and DNA synthesis ceases. Cycloheximide added to replenished deficient cells after completion of DNA duplication inhibits cell division. The total cellular protein and RNA in replenished cells treated with cycloheximide does not change. B12 added to deficient cells does not stimulate the incorporation of [14C]leucine into protein during resumption and completion of DNA duplication. However, there is a large increase in [14C]leucine incorporation into the protein of these cells soon after completion of DNA duplication and before resumption of cell division. The addition of cycloheximide to B12-replenished or to nonreplenished deficient cells rapidly inhibits the incorporation. We suggest that the addition of B12 accelerates the rate of DNA synthesis in the deficient cells and that possibly no new protein synthesis is required except for mitosis. However, protein synthesis is needed for continuous DNA synthesis.

Vitamin B12 Content of Liver and Serum in Malignant Neoplasia

1962 ◽  
Vol 42 (4) ◽  
pp. 414-418 ◽  
Author(s):  
Robert S. Nelson ◽  
Vasant M. Doctor
Keyword(s):  
Vitamin B12 ◽  
Malignant Neoplasia

55: The Risk of Vitamin B12 Deficiency is Low after Ileal Orthotopic Bladder Substitution

2004 ◽  
Vol 171 (4S) ◽  
pp. 15-15
Author(s):  
Urs E. Studer ◽  
Richard Aebischer ◽  
Katharina Ochsner ◽  
Werner W. Hochreiter
Keyword(s):  
Vitamin B12 ◽  
Vitamin B12 Deficiency ◽  
B12 Deficiency ◽  
Bladder Substitution

Switching to Oral Vitamin B12 Replacement

2006 ◽  
Vol 39 (18) ◽  
pp. 30
Author(s):  
JON O. EBBERT ◽  
ERIC G. TANGALOS
Keyword(s):  
Vitamin B12 ◽  
Oral Vitamin
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