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.

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.

Interferon inhibition of DNA synthesis and cell division

1972 ◽  
Vol 18 (2) ◽  
pp. 145-151 ◽  
Author(s):  
M. V. O'Shaughnessy ◽  
S. H. S. Lee ◽  
K. R. Rozee
Keyword(s):  
Cell Division ◽  
Antiviral Activity ◽  
Dna Synthesis ◽  
S Phase ◽  
Cell Suspensions ◽  
Depression Effect ◽  
Growth Depression ◽  
Synchronized Cells ◽  
Inhibition Of Dna Synthesis ◽  
New Protein

Using monodispersed cell suspensions, interferon preparations were shown to have both a lethal and a growth-depression effect in the same concentration range as that required for antiviral activity. In addition, synchronized cells treated with interferon respond by delaying their normal uptake of thymidine during S phase until after a period during which new protein is synthesized. Puromycin added during this period prevents both the synthesis of this protein and the subsequent synthesis of DNA.

CELL DIVISION AND DNA SYNTHESIS IN THE MOUSE UTERUS DURING CONTINUOUS OESTROGEN TREATMENT

1972 ◽  
Vol 55 (3) ◽  
pp. 507-513 ◽  
Author(s):  
AUDREY E. LEE
Keyword(s):  
Drinking Water ◽  
Cell Division ◽  
Dna Synthesis ◽  
Thymidine Incorporation ◽  
Initial Increase ◽  
Luminal Epithelium ◽  
Third Wave ◽  
Mouse Uterus ◽  
Oestrogen Treatment ◽  
Second Wave

SUMMARY Continuous oestrogen stimulation produced an initial increase in mitosis and [3H]thymidine incorporation in the mouse uterine luminal epithelium on days 2 and 3 of treatment, but activity fell to the level of the untreated uterus on days 4 and 5. The implications of this control of cell division are discussed. A second wave of activity occurred about a week later, and in the longest experiment a third wave was seen on days 19 to 21. This pattern was similar to that seen in the glandular epithelium. There was little cell division in the stroma or myometrium. The rhythm was not due to diurnal variation. It was seen after treatment with oestrone and oestradiol, given either by injection or in the drinking water.

scholarly journals Insulin stimulates synthesis of soluble proteins in isolated rat hepatocytes

1980 ◽  
Vol 190 (3) ◽  
pp. 615-619 ◽  
Author(s):  
R L Clark ◽  
R J Hansen
Keyword(s):  
Protein Synthesis ◽  
Rat Hepatocytes ◽  
Isolated Hepatocytes ◽  
Cellular Protein ◽  
Soluble Proteins ◽  
Leucine Incorporation ◽  
Isolated Rat Hepatocytes ◽  
Hepatic Protein Synthesis ◽  
Isolated Rat ◽  
Stimulation Of

The incorporation of [3H]leucine into soluble cellular protein was measured in isolated hepatocytes at extracellular leucine concentrations ranging from 0.15 to 20.0 mM. Insulin caused a 12—15% stimulation of [3H]leucine incorporation in the presence of high extracellular leucine concentrations. It is concluded that insulin causes a small but significant increase in the rate of hepatic protein synthesis.

scholarly journals Long-lived crowded-litter mice have an age-dependent increase in protein synthesis to DNA synthesis ratio and mTORC1 substrate phosphorylation

2014 ◽  
Vol 307 (9) ◽  
pp. E813-E821 ◽  
Author(s):  
Joshua C. Drake ◽  
Danielle R. Bruns ◽  
Frederick F. Peelor ◽  
Laurie M. Biela ◽  
Richard A. Miller ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Dna Synthesis ◽  
Litter Size ◽  
Cellular Structures ◽  
Mtorc1 Signaling ◽  
Age Dependent ◽  
Model Protein ◽  
Substrate Phosphorylation ◽  
Mtor Complex 1 ◽  
New Protein

Increasing mouse litter size [crowded litter (CL)] presumably imposes a transient nutrient stress during suckling and extends lifespan through unknown mechanisms. Chronic calorically restricted and rapamycin-treated mice have decreased DNA synthesis and mTOR complex 1 (mTORC1) signaling but maintained protein synthesis, suggesting maintenance of existing cellular structures. We hypothesized that CL would exhibit similar synthetic and signaling responses to other long-lived models and, by comparing synthesis of new protein to new DNA, that insight may be gained into the potential preservation of existing cellular structures in the CL model. Protein and DNA synthesis was assessed in gastroc complex, heart, and liver of 4- and 7-mo CL mice. We also examined mTORC1 signaling in 3- and 7-mo aged animals. Compared with controls, 4-mo CL had greater DNA synthesis in gastroc complex with no differences in protein synthesis or mTORC1 substrate phosphorylation across tissues. Seven-month CL had less DNA synthesis than controls in heart and greater protein synthesis and mTORC1 substrate phosphorylation across tissues. The increased new protein-to-new DNA synthesis ratio suggests that new proteins are synthesized more so in existing cells at 7 mo, differing from 4 mo, in CL vs. controls. We propose that, in CL, protein synthesis shifts from being directed toward new cells (4 mo) to maintenance of existing cellular structures (7 mo), independently of decreased mTORC1.

scholarly journals MACROMOLECULAR EVENTS LEADING TO CELL DIVISION IN TETRAHYMENA PYRIFORMIS AFTER REMOVAL AND REPLACEMENT OF REQUIRED PYRIMIDINES

1965 ◽  
Vol 25 (2) ◽  
pp. 9-19 ◽  
Author(s):  
Ivan L. Cameron
Keyword(s):  
Cell Division ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Nuclear Dna ◽  
Early Period ◽  
Tetrahymena Pyriformis ◽  
Cell Number ◽  
Cellular Protein ◽  
Cellular Content ◽  
Endogenous Protein

Tetrahymena pyriformis were brought to a non-growing state by removal of pyrimidines from their growth medium. During pyrimidine deprivation cell number increased 3- to 4 fold, and this increase was accompanied by one or more complete cycles of macronuclear DNA replication. Autoradiographic studies show that endogenous protein and RNA were turning over throughout starvation and that RNA breakdown products were used to support the DNA synthesis that occurred during the early period of starvation. However, after 72 hours of starvation all DNA synthesis and cell division had ceased. Feulgen microspectrophotometry shows the macronuclei of these cells to have been stopped at a point prior to DNA replication (G1 stage). After pyrimidine replacement the incorporation of H3-uridine, H3-adenosine, and H3-leucine was measured by the autoradiographic grain counting method. The results indicate that RNA synthesis began to increase almost immediately, but that there was a lag of almost an hour before an increase in protein synthesis. In agreement with the autoradiographic data, chemical data also show that cellular content of RNA began to increase shortly after pyrimidine replacement but that cellular protein content did not increase until about one hour later. Pulse labeling of the cells with H3-thymidine at intervals after pyrimidine replacement shows that labeled macronuclei first began to appear at 150 minutes; that 98 per cent of the macronuclei were in DNA synthesis at 240 to 270 minutes; and that the percentage then began to decrease from 300 to 390 minutes, at which time only 25 per cent of the macronuclei were labeled. Cellular content of DNA did not increase for at least 135 minutes after pyrimidine replacement; however, just before the first cells divided (360 minutes) the DNA content had doubled. After pyrimidine replacement the cells first began to divide at 360 minutes, and 50 per cent had divided at 420 minutes; however, all cells had not divided until 573 minutes. This technique of chemical synchronization of cells in mass cultures makes feasible detailed biochemical analysis of events leading to nuclear DNA replication and cell division.

Angiotensin II stimulation of protein synthesis and cell growth in chick heart cells

1990 ◽  
Vol 259 (2) ◽  
pp. H610-H618 ◽  
Author(s):  
K. M. Baker ◽  
J. F. Aceto
Keyword(s):  
Protein Synthesis ◽  
Angiotensin Ii ◽  
Cell Growth ◽  
Relative Rate ◽  
Renin Angiotensin System ◽  
Cellular Protein ◽  
Cardiac Cells ◽  
Heart Cells ◽  
Ang Ii ◽  
Total Cellular Protein

The octapeptide [Ile5]angiotensin II (ANG II), which is the principal circulating hormone of the renin-angiotensin system, could modulate or mediate cardiac hypertrophy via indirect effects, through increases in total peripheral vascular resistance, or by direct effects on cardiac cells, which result in increased protein synthesis and cell growth. In this study we determined whether ANG II stimulated protein synthesis and cell growth in cultures of embryonic chick myocytes. After 3 h of exposure to ANG II, there were significant increases in total cellular protein at 120, 144, and 168 h and in the relative rate of protein synthesis at 120 and 144 h. There was a significant increase in the fractional rate of protein synthesis of 32.2% (0.0119 +/- 0.0008 h-1 for ANG II stimulated and 0.0090 +/- 0.0003 h-1 for control). The stimulatory effects of ANG II on protein synthesis and cell growth were inhibited by the ANG II antagonist [Sar1,Ile8]ANG II and the hexapeptide ANG II-(3-8). ANG II significantly increased total RNA levels in myocytes, at 12 h after exposure to the peptide. The stimulatory effect of ANG II (32%) on total cellular protein was slightly greater than that seen with norepinephrine (20%) in contrast to the greater stimulatory effect seen with phorbol 12,13-dibutyrate (47%). ANG II and [Sar1,Ile8]ANG II each stimulated increases in cytosolic-free Ca2+, whereas ANG II-(3-8) did not. Growth-related effects of changes in the chronotropic state of the myocytes were excluded, in that, ANG II-stimulated increases in protein synthesis and cellular protein were not inhibited by potassium chloride depolarization of the cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Protein Synthesis During the First Three Cleavages in Pond Snail Eggs (Lymnaea Stagnalis)

1968 ◽  
Vol 23 (11) ◽  
pp. 1512-1516 ◽  
Author(s):  
Brigitte Jockusch
Keyword(s):  
Protein Synthesis ◽  
Cell Division ◽  
Lymnaea Stagnalis ◽  
Leucine Incorporation ◽  
Pond Snail ◽  
Blastula Stage ◽  
Egg Capsules ◽  
The Third ◽  
Insoluble Material ◽  
Inorganic Medium

Egg cells of the pond snail Lymnaea stagnalis were isolated and reared in an inorganic medium, in which they reached the blastula stage with the same rate and yield as in the egg capsules. Synchrony of cell division was 70—90% depending on temperature and number of cell division. 3H-leucine incorporation into hot TCA-insoluble material as a function of developmental stage was studied by autoradiography. The rate of leucine incorporation during the metaphase of the first three cell divisions was found to be ca. 30% of the incorporation rate during the corresponding interphases. The interphase rates increased from a very low level before nuclear fusion to a 25 fold value in the third interphase. 3H-leucine incorporation could be inhibited by 78% by 5 × 10-3 M puromycin and hence seems to represent protein synthesis.

Stability of histone mRNAs is related to their location in polysomes

1986 ◽  
Vol 64 (2) ◽  
pp. 99-105 ◽  
Author(s):  
R. Curtis Bird ◽  
Frederik A. Jacobs ◽  
Bruce H. Sells
Keyword(s):  
Protein Synthesis ◽  
Dna Synthesis ◽  
Histone H4 ◽  
Histone Mrna ◽  
Specific Mechanism ◽  
Histone Mrnas ◽  
Inhibition Of Protein Synthesis ◽  
Rate Of Decay ◽  
Inhibition Of Dna Synthesis ◽  
New Protein

Synthesis of histone mRNAs is closely coupled to DNA synthesis. Following inhibition of DNA synthesis in L6 myoblasts with cytosine arabinoside, a coordinate and exaggerated rate of degradation of histone mRNAs occurs while other mRNAs, encoding ribosomal protein L32 and actin, are unaffected. Inhibition of protein synthesis by puromycin, emetine, or cycloheximide stabilizes histone mRNAs and results in their accumulation. When inhibition of DNA synthesis was followed immediately by inhibition of protein synthesis, the exaggerated rate of decay of the existing subspecies of histone H4 mRNAs was prevented and histone mRNA accumulated. If inhibition of protein synthesis was delayed longer than 3 minutes following inhibition of DNA synthesis, the ability to accumulate H4 mRNAs was lost. Furthermore, new protein synthesis was required to activate the mechanism which specifically destabilized histone mRNA. Puromycin was able to prevent the exaggerated rate of degradation of the various subspecies of H4 mRNA when added up to 15 min after inhibition of DNA synthesis, whereas emetine was effective only when added up to 5 min following inhibition of DNA synthesis. These data suggest that histone H4 mRNAs in polysomes are better targets than those released from polysomes for the specific mechanism which destabilizes histone mRNAs upon inhibition of DNA synthesis.

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