scholarly journals SYNTHETIC ACTIVITIES DURING SPERMATOGENESIS IN THE LOCUST

1965 ◽  
Vol 25 (2) ◽  
pp. 387-395 ◽  
Author(s):  
Nirmal K. Das ◽  
Elsie P. Siegel ◽  
Max Alfert
Keyword(s):  
Protein Synthesis ◽  
Nucleic Acid ◽  
Dna Synthesis ◽  
X Chromosome ◽  
Rna Synthesis ◽  
Schistocerca Gregaria ◽  
Tritiated Thymidine ◽  
Chromatin Condensation ◽  
Chromosome Condensation ◽  
Meiotic Cycle

Isolated testes of the locust Schistocerca gregaria were immersed in solutions of tritiated thymidine, cytidine, uridine, or arginine for short periods to study nucleic acid and protein synthesis during spermatogenesis. DNA synthesis in this tissue is completed prior to initiation of meiosis. Protein synthesis continues throughout the whole meiotic cycle as well as during spermatid development. Meiotic cells, except those in metaphase through early telophase, and early spermatids are also actively synthesizing RNA. The heteropycnotic X-chromosome does not produce RNA at any stage of spermatogenesis. The rates of protein and particularly RNA synthesis decrease as chromosome condensation progresses. Depression of RNA synthesis, however, is not always accompanied by cytologically detectable condensation of chromatin, since very little or no RNA is synthesized in spermatids in which chromatin condensation has barely begun.

scholarly journals MACROMOLECULAR SYNTHESES RELATED TO THE REPRODUCTIVE CYST OF TETRAHYMENA PATULA

1973 ◽  
Vol 59 (3) ◽  
pp. 615-623 ◽  
Author(s):  
P. R. Gabe ◽  
L. E. de Bault
Keyword(s):  
Protein Synthesis ◽  
Dna Synthesis ◽  
Generation Time ◽  
Rna Synthesis ◽  
Culture Medium ◽  
Tritiated Thymidine ◽  
Growth Cycle ◽  
The Third ◽  
Rna And Protein Synthesis ◽  
The Mean

Macromolecular syntheses in encysted Tetrahymena patula were studied using Feulgen fluorescence cytophotometry, autoradiography, and inhibitors of RNA and protein synthesis. Cycloheximide significantly depressed protein synthesis and D-actinomycin effectively blocked RNA synthesis. Under these conditions, the cells within the cyst were unable to divide. Both cytophotometric measurements and autoradiographic data with tritiated thymidine show that DNA synthesis does not occur during the encystment divisions. Excysted cells placed in nutrient broth medium showed a prolonged generation time after the first cell growth cycle, and by the third generation the mean DNA content per cell was almost triple that of starved excysted cells. These findings indicate that (a) the encystment divisions require RNA and protein synthesis, which are apparently effected through turnover, (b) the encystment division cycles occur in the absence of DNA synthesis, and (c) excysted cells placed in culture medium may go through more than one DNA replication per cell cycle.

scholarly journals The Effect of L-Asparaginase on the Nucleic Acid Metabolism and Cell Cycle of Human Leukemia Cells

Blood ◽  
1972 ◽  
Vol 39 (4) ◽  
pp. 575-580 ◽  
Author(s):  
E. Fred Saunders
Keyword(s):  
Cell Cycle ◽  
Nucleic Acid ◽  
Dna Synthesis ◽  
Rna Synthesis ◽  
Lymphoblastic Leukemia ◽  
Buffy Coat ◽  
Leukemic Cells ◽  
Nucleic Acid Metabolism ◽  
Rapid Decline ◽  
Human Leukemia

Abstract The effect of L-asparaginase on the cell cycle and nucleic acid synthesis of leukemic cells was studied in five children with acute lymphoblastic leukemia. Following an intravenous infusion of the drug, serial marrow samples were obtained for buffy coat volume, mitotic index, and autoradiographic assessment of DNA and RNA synthesis using tritiated thymidine and tritiated uridine, respectively. A rapid decline in buffy coat volume indicated a lytic effect on lymphoblasts. There was a greater kill of proliferative (blasts in the cell cycle) than nonproliferative (G0) leukemic cells. Mitotic indices changed little until 24 hr; in contrast, thymidine labeling indices decreased markedly to less than 50% of control by 6 hr. The changes in labeling indices prior to changes in mitotic indices indicated that L-asparaginase blocked the entrance of cells into the DNA synthesis period of the cell cycle. Cells already in DNA synthesis appeared to continue into mitosis. Uridine labeling indices decreased progressively in all patients. Uridine uptake was inhibited equally in both proliferative and nonproliferative blasts. Therefore, inhibition of RNA synthesis by L-asparaginase was independent of the proliferative activity of the marrow.

Protein and Nucleic Acid Syntheses in Dark-dormant Common Purslane(Portulaca oleracea)Seed

Weed Science ◽  
1978 ◽  
Vol 26 (6) ◽  
pp. 669-672 ◽  
Author(s):  
Bonnie J. Reger ◽  
Ida E. Yates
Keyword(s):  
Protein Synthesis ◽  
Nucleic Acid ◽  
Rna Synthesis ◽  
Acid Synthesis ◽  
Portulaca Oleracea ◽  
Dark Incubation ◽  
Radicle Protrusion ◽  
Lag Period ◽  
Common Purslane ◽  
H Protein

Dark-incubated common purslane(Portulaca oleraceaL.) seed synthesize very little protein and essentially no nucleic acids. Dark-incubated seed incorporate only 14 × 10−3nmoles14C-leucine/mg protein/12-h dark. In contrast, seed exposed to 12-h light following 24-h dark incubation incorporate 365 × 10−3-nmoles14C-leucine/mg protein/12-h light. Once dormancy is broken by exposure of seed to light, initiation of radicle protrusion occurs at 12 h. Protein synthesis gradually increases with time in the light and precedes nucleic acid synthesis which is associated with radicle protrusion. During the 12-h lag period preceding radicle protrusion protein synthesis increases significantly by 3 to 9 h in light, RNA synthesis by 9 h in light, and DNA synthesis by 12 h in light. After 12 h in light,32P can be detected in all nucleic acid fractions, DNA and RNAs.

A comparison of the synthesis of DNA, RNA and proteins in the embryos of after-ripened and thermo- or FR-dormant Agrostemma githago L. seeds

1995 ◽  
Vol 5 (2) ◽  
pp. 87-97 ◽  
Author(s):  
U. Gerth ◽  
D. Bernhardt
Keyword(s):  
Protein Synthesis ◽  
Dna Synthesis ◽  
Rna Synthesis ◽  
Gradual Decrease ◽  
Two Dimensional ◽  
Dark Incubation ◽  
Low Level ◽  
Developmental Arrest ◽  
Stimulation Of

AbstractImbibed embryos of after-ripened and secondarily thermo- and FR-dormant Agrostemma githago seeds were investigated as to their ability to synthesize DNA, RNA and proteins with the aim of finding characteristic differences connected with the induction and maintenance of developmental arrest. A gradual decrease in DNA synthesis was observed during the induction of thermodormancy. However, DNA synthesis was stimulated up to that of embryos of 30–h-imbibed after-ripened seeds within 24 h approximately after transferring the thermodormant seeds into temperatures which normally allow germination. DNA synthesis of embryos of FR-dormant seeds remained constant at a relatively low level during 7 d FR and another 7 d dark incubation. RNA synthesis decreased to different extents during induction of thermo- and FR-dormancy when it was arrested at a relatively low level in seeds transferred to temperatures which normally allow germination. Processes leading to an increase in RNA synthesis such as in embryos of after-ripened seeds appeared to be quantitatively and/or qualitatively repressed. Interestingly, protein synthesis was extremely depressed during induction of thermodormancy whereas it was slightly stimulated during induction of FR-dormancy. Nevertheless two-dimensional protein PAGE revealed several polypeptides which were new, increased, decreased or not synthesized predominantly in axes of thermo- and FR-dormant seeds in comparison to germinating after-ripened seeds. It is suggested that a connection exists between these polypeptides and the repression of germination. After transferring seconarily dormant seeds to temperatures which normally allow germination, a temporary stimulation of protein synthesis could be observed in both cases.

scholarly journals Evidence for endogenous polypeptide-mediated inhibition of cell-cycle transit in human diploid cells.

1982 ◽  
Vol 94 (1) ◽  
pp. 187-192 ◽  
Author(s):  
G C Burmer ◽  
C J Zeigler ◽  
T H Norwood
Keyword(s):  
Cell Cycle ◽  
Protein Synthesis ◽  
Dna Synthesis ◽  
Tritiated Thymidine ◽  
Protein Synthesis Inhibitor ◽  
Synthesis Inhibitor ◽  
Human Diploid Fibroblasts ◽  
Senescent Phenotype ◽  
Human Diploid Cells ◽  
Diploid Cells

Previous studies have shown that the senescent phenotype is dominant with respect to DNA synthesis in fusions between late passage and actively replicating human diploid fibroblasts. Brief postfusion treatments with the protein synthesis inhibitor cycloheximide (CHX) or puromycin have been found to significantly delay (by 24-48 h) the inhibition of entry into DNA synthesis of young nuclei in heterokaryons after fusion with senescent cells. A significant fraction of the senescent nuclei incorporated tritiated thymidine in CHX-treated heterokaryons. The optimal duration of exposure to CHX was 1-3 h immediately after fusion, although treatments beginning as late as 9 h after fusion elevated the heterokaryon labeling index. Prefusion treatments with CHX were without a significant effect. These results are consistent with the interpretation that regulatory cell cycle inhibitor(s) which are dependent upon protein synthesis may be present in heterokaryons between senescent and actively replicating cells.

Insulin stimulates macromolecular synthesis in cultured glial cells from rat brain

1985 ◽  
Vol 249 (5) ◽  
pp. C484-C489 ◽  
Author(s):  
D. W. Clarke ◽  
F. T. Boyd ◽  
M. S. Kappy ◽  
M. K. Raizada
Keyword(s):  
Protein Synthesis ◽  
Growth Factor ◽  
Dna Synthesis ◽  
Rat Brain ◽  
Glial Cells ◽  
Rna Synthesis ◽  
Macromolecular Synthesis ◽  
Total Response ◽  
Dose Dependent ◽  
Stimulation Of

The effect of insulin on macromolecular synthesis in glial cells cultured from brains of 1-day-old rats was studied to investigate the role of insulin in brain growth. Insulin caused a dose-dependent stimulation of protein synthesis (measured by [3H]valine incorporation into protein) that became significant by 7 nM insulin. Maximal stimulation of protein synthesis of 145% of control occurred with 18 nM insulin. Long-term protein synthesis was also stimulated to 136% of control by insulin in a dose-dependent manner after 6 days of insulin incubation. Insulin also stimulated net RNA and DNA synthesis (measured by [3H]uridine and [3H]thymidine incorporation into RNA or DNA, respectively) with significant stimulation by 2 nM insulin. Net RNA synthesis stimulation was maximal at 120% of control by 18 nM insulin. Plateau stimulation of DNA synthesis of 175% of control was reached by 200 nM insulin. The effects of insulin on glial protein and RNA synthesis appear to be mediated completely by the insulin receptor. Insulin, in physiological concentrations, stimulated glial DNA synthesis via its interaction with the insulin receptor (46% of total response). At supraphysiological concentrations insulin may have stimulated DNA synthesis via its cross-reactivity with the insulinlike growth factor I receptor (54% of total response). Thus insulin, at concentrations known to exist in the brain, stimulates the processes necessary for growth in the glial cell and is an important growth factor in the developing rat brain.

THE EFFECT OF ACTINOBOLIN ON NUCLEIC ACID AND PROTEIN SYNTHESIS IN ESCHERICHIA COLI

1966 ◽  
Vol 12 (3) ◽  
pp. 515-520 ◽  
Author(s):  
D. E. Hunt ◽  
R. F. Pittillo ◽  
E. P. Johnson ◽  
F. C. Moncrief
Keyword(s):  
Escherichia Coli ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Nucleic Acid ◽  
Mechanism Of Action ◽  
Rna Synthesis ◽  
The Other ◽  
Cross Resistance ◽  
Inhibition Of Protein Synthesis

Actinobolin inhibits protein synthesis in Escherichia coli. When the antibiotic is added to a culture at the time of inoculation, RNA synthesis is also inhibited. Inhibition of RNA synthesis appears to be a consequence of inhibition of protein synthesis. Cross-resistance experiments suggest that the mechanism of action of actinobolin differs from that of the other inhibitors of protein synthesis, chloramphenicol and sparsomycin. Phenylalanine prevents the action of actinobolin provided the amino acid and antibiotic are added simultaneously; this effect is not observed if the phenylalanine is added 1 hour after the addition of the antibiotic. Evidence is presented that the mechanism by which phenylalanine prevents inhibition by actinobolin differs from that which has been suggested for azaserine and p-fluorophenylalanine.

scholarly journals RELATIONSHIPS BETWEEN NUCLEIC ACID SYNTHETIC PATTERNS AND ENCYSTMENT IN AGING UNAGITATED CULTURES OF ACANTHAMOEBA CASTELLANII

1971 ◽  
Vol 49 (2) ◽  
pp. 498-506 ◽  
Author(s):  
V. L. Rudick
Keyword(s):  
Nucleic Acid ◽  
Dna Synthesis ◽  
Dna Content ◽  
Rna Synthesis ◽  
Actinomycin D ◽  
Acanthamoeba Castellanii ◽  
Disc Electrophoresis ◽  
Dna And Rna ◽  
Inhibition Of Dna Synthesis ◽  
Growth Deceleration

Changes in the levels of DNA and RNA syntheses have been studied in unagitated cultures of Acanthamoeba castellanii during the phases of logarithmic multiplication (LM) and population growth deceleration (PGD). Pulse-labeling experiments show that the rate of DNA synthesis decreases at the same time that DNA per cell is known to drop by 50%. The drop in DNA content has been explained by demonstrating with hydroxyurea that the majority of LM amebas can replicate once when DNA synthesis is inhibited and, therefore, must be in G2, whereas the PGD amebas cannot multiply in the presence of inhibitor and, therefore, must be in G1. The inhibition of DNA synthesis in LM or PGD cells has been shown to induce encystment. The rate of RNA synthesis, as illustrated by pulse-labeling experiments, increases 25% in late LM-early PGD while RNA per cell increases 75%. The rate of synthesis then decreases 65%. The majority of accumulated RNA has been demonstrated to be ribosomal by disc electrophoresis. By using actinomycin D at different stages during the RNA build-up, the ability of the amebas to encyst has been shown to depend on the presence of this RNA. The observations on DNA and RNA are discussed with respect to the occurrence of cysts in the cultures during PGD.

Sign in / Sign up

Export Citation Format

Share Document