Autoradiographic evidence for the effects of light on RNA and DNA synthesis during chloroplast replication in spores of Polytrichum

1977 ◽  
Vol 28 (1) ◽  
pp. 61-70
Author(s):  
L.B. Kass ◽  
D.J. Paolillo
Keyword(s):  
Dna Synthesis ◽  
Nuclear Dna ◽  
Acid Synthesis ◽  
S Phase ◽  
Temporal Separation ◽  
Dark Incubation ◽  
Chloroplast Replication ◽  
Rna And Dna Synthesis ◽  
Rna And Dna ◽  
Stimulation Of

Light stimulates the incorporation of [3H]uridine and [3H]thymidine in addition to plastid replication in germinating Polytrichum spores. Significant amounts of [3H]uridine and [3H]thymidine are incorporated in darkness but not to the same level as in light. Plastids continue to produce nucleic acids when their capacity to multiply is suspended due to the absence of light. However, a higher amount of DNA synthesis in the light is correlated with the result that chloroplast replication begins again in the light after prolonged dark incubation. An imperfect association of plastid replication and nucleic acid synthesis is suggested by the lack of stimulation of DNA synthesis by light during plastid replication in the first 8 h of incubation. A temporal separation can be demonstrated for chloroplast and nuclear DNA synthesis at the beginning of germination in Polytrichum spores, with DNA synthesis in the chloroplasts preceding that in the nucleus. The mitotic S phase is longer than 16 h for at least half of the nuclei.

scholarly journals Lomofungin as an inhibitor of nucleic acid synthesis in Saccharomyces cerevisiae

1974 ◽  
Vol 142 (3) ◽  
pp. 457-463 ◽  
Author(s):  
Michael Cannon ◽  
Antonio Jimenez
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Synthesis ◽  
Rna Synthesis ◽  
Acid Synthesis ◽  
Growth Conditions ◽  
Dna And Rna ◽  
Dna And Rna Synthesis ◽  
Inhibition Of Dna Synthesis ◽  
Rna And Dna Synthesis ◽  
Rna And Dna

1. The antibiotic lomofungin was found to be a potent inhibitor of both DNA and RNA synthesis in Saccharomyces cerevisiae. Under selected growth conditions inhibition of DNA synthesis by the drug preceded inhibition of RNA synthesis. 2. Although in general lomofungin inhibited synthesis of ribosomal RNA and polydisperse RNA more effectively than that of low-molecular-weight RNA, under certain conditions the drug inhibited almost completely synthesis of both 4S and 5S RNA. 3. Inhibition of both RNA and DNA synthesis may be explained if RNA synthesis is required for DNA synthesis in yeast. Alternatively, lomofungin, in addition to interacting with DNA-dependent RNA polymerase, might interfere with a component(s) of the DNA-synthetic apparatus. The drug may thus prove to be of considerable value in studies of DNA synthesis in eukaryotes.

scholarly journals LIMITED DNA SYNTHESIS IN THE ABSENCE OF PROTEIN SYNTHESIS IN PHYSARUM POLYCEPHALUM

1966 ◽  
Vol 31 (3) ◽  
pp. 577-583 ◽  
Author(s):  
J. E. Cummins ◽  
H. P. Rusch
Keyword(s):  
Protein Synthesis ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Physarum Polycephalum ◽  
Nuclear Dna ◽  
S Phase ◽  
Early Prophase ◽  
Late Prophase ◽  
Removal Experiments ◽  
Inhibitor Of Protein Synthesis

Actidione (cycloheximide), an antibiotic inhibitor of protein synthesis, blocked the incorporation of leucine and lysine during the S phase of Physarum polycephalum. Actidione added during the early prophase period in which mitosis is blocked totally inhibited the initiation of DNA synthesis. Actidione treatment in late prophase, which permitted mitosis in the absence of protein synthesis, permitted initiation of a round of DNA replication making up between 20 and 30% of the unreplicated nuclear DNA. Actidione treatment during the S phase permitted a round of replication similar to the effect at the beginning of S. The DNA synthesized in the presence of actidione was replicated semiconservatively and was stable through at least the mitosis following antibiotic removal. Experiments in which fluorodeoxyuridine inhibition was followed by thymidine reversal in the presence of actidione suggest that the early rounds of DNA replication must be completed before later rounds are initiated.

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