RNA Synthesis as the Basis for EPTC and 2,4-D Antagonism

Weed Science ◽  
1972 ◽  
Vol 20 (1) ◽  
pp. 8-11 ◽  
Author(s):  
C. E. Beste ◽  
M. M. Schreiber
Keyword(s):  
Acetic Acid ◽  
Ribosomal Rna ◽  
Preliminary Analysis ◽  
Rna Synthesis ◽  
Selective Inhibition ◽  
Acid Synthesis ◽  
Inhibition Of Growth ◽  
Dichlorophenoxy Acetic Acid ◽  
Soybean Tissue ◽  
Hypocotyl Segments

Three-day-old soybean(Glycine max(L.) Merr., ‘Hawkeye 63′) hypocotyl segments (0.5 to 1.5 cm below the cotyledons) were utilized to evaluate the effects of the antagonistic interaction ofS-ethyl dipropylthiocarbamate (EPTC) and (2,4-dichlorophenoxy)acetic acid (2,4-D) on growth and nucleic acid synthesis. EPTC inhibited growth and RNA synthesis in soybean tissue. The addition of 2,4-D with EPTC was antagonistic to EPTC inhibition of growth and caused an increase in total RNA synthesis. Analysis of soybean tissue nucleic acids by methylated-albumin-kieselguhr(MAK) column chromatography showed that EPTC inhibited ribosomal-RNA (r-RNA), DNA like RNA (D-RNA), and tenaciously-bound-RNA (TB-RNA) synthesis. The combination of 2,4-D with EPTC caused an increase in D-RNA and TB-RNA synthesis compared to the EPTC treatment alone. The 2,4-D-enhanced synthesis of D-RNA and TB-RNA in the presence of EPTC appears to be the basis of the antagonism between EPTC and 2,4-D. Preliminary analysis of r-RNA indicated that EPTC preferentially inhibited the synthesis of 18S r-RNA more than 25S r-RNA and that 2,4-D had no effect on this selective inhibition.

Ribonucleic acid synthesis inPlasmodium knowlesimaintained bothin vivoandin vitro

Parasitology ◽  
1975 ◽  
Vol 71 (2) ◽  
pp. 199-209 ◽  
Author(s):  
P. I. Trigg ◽  
P. G. Shakespeare ◽  
Susan J. Burt ◽  
Sally I. Kyd
Keyword(s):  
Ribosomal Rna ◽  
Rna Synthesis ◽  
Nuclear Division ◽  
Plasmodium Knowlesi ◽  
Acid Synthesis ◽  
Agarose Gel Electrophoresis ◽  
Trophozoite Stage ◽  
Late Trophozoite

RNA extracted from purified parasites ofPlasmodium knowlesiwas fractionated using agarose gel electrophoresis. Preparations from parasites grown bothin vivoandin vitrocontained species of RNA with sedimentation coefficients of 4·0S, 5·0S, 16·6S, 24·2S, 31·4S, 38·0S and 48·3S. There was less RNA present in parasites grownin vitrothan the equivalent stage parasites grownin vivobut the proportional amounts of the various species of RNA was similar in both cases. It is suggested that the 24·2S and 16·6S species of RNA are ribosomal and that the high molecular weight 31·4S, 38·0S and 48·0S species are ribosomal precursors. Ribosomal RNA synthesis occurs throughout the cell cycle during growth from the ring to the schizont stage; maximum incorporation of [H3]-adenosine occurs at the late trophozoite stage before nuclear division.

An Investigation on the Mechanism of Action of Propachlor

Weed Science ◽  
1975 ◽  
Vol 23 (2) ◽  
pp. 142-147 ◽  
Author(s):  
W. B. Duke ◽  
F. W. Slife ◽  
J. B. Hanson ◽  
H. S. Butler
Keyword(s):  
Mechanism Of Action ◽  
Root Elongation ◽  
Rna Synthesis ◽  
Protein Biosynthesis ◽  
Acid Synthesis ◽  
Atp Formation ◽  
Inhibition Of Growth ◽  
Primary Mechanism ◽  
Cucumus Sativus ◽  
Inhibition Of Root Elongation

Studies were conducted to examine over time the effects of propachlor (2-chloro-N-isopropylacetanilide) on the growth of cucumber (Cucumus sativusL. ‘Straight Eight’) roots and associated biosynthetic reactions. Complete inhibition of root elongation occurred within 16 hr after exposure to propachlor. Inhibition of growth was not found to be a result of an effect on ATP formation or respiration. Protein biosynthesis was reduced several hours before the observed inhibition of growth therefore implicating it as the causal factor. Inhibition of protein synthesis occurred prior to an observed reduction in RNA synthesis suggesting that the primary effect of propachlor is on protein biosynthesis and that its effect on nucleic acid synthesis is secondary. It is concluded that the primary mechanism of action of propachlor is its effect on nascent protein biosynthesis.

scholarly journals RNA SYNTHESIS IN HELA CELLS

1970 ◽  
Vol 47 (3) ◽  
pp. 734-744 ◽  
Author(s):  
Thoru Pederson ◽  
Elliott Robbins
Keyword(s):  
Ribosomal Rna ◽  
Hela Cells ◽  
Rna Synthesis ◽  
Close Correlation ◽  
Selective Inhibition ◽  
Transfer Rna ◽  
Extracellular Medium ◽  
Hypertonic Medium ◽  
Nuclear Rna ◽  
Ribosomal Precursor

Interphase HeLa cells manifest a stepwise shutoff of RNA synthesis when the tonicity of the extracellular medium is gradually increased. Synthesis of heterogeneous nuclear RNA is most sensitive and is selectively inhibited at 1.5 times isotonicity (450 milliosmols/liter), while 45S ribosomal RNA synthesis is not affected significantly below 2.0 times isotonicity. Transfer RNA synthesis is least sensitive to increased osmolarity and is not completely inhibited until the electrolyte concentration of the medium is elevated to 2.8 times isotonicity. Although the transcription and methylation of 45S ribosomal precursor is unaffected at 1.5 times isotonicity, there is pronounced impairment of its processing into 32S and 18S RNA. Using a refined cell synchronization technique, we have been able to compare these effects of hypertonicity with the shutoff of RNA synthesis which occurs during the G2-prophase interval of the cell division cycle. In this case, as with random cells in hypertonic medium, a selective inhibition of heterogeneous nuclear RNA synthesis and slowed processing of 45S ribosomal RNA were found, whereas synthesis of 45S and transfer RNA continued unabated throughout G2-prophase. While it is known that RNA synthesis essentially ceases during metaphase, we have noted that transfer RNA synthesis continues in metaphase at 10–15% of the interphase rate, which is of particular interest in view of the relative resistance of this species to hypertonicity. The close correlation between the patterns of cessation of RNA synthesis at mitosis and during exposure to hypertonic medium supports our earlier contention that alteration of intracellular electrolyte levels provides a useful model for studying the mechanism of mitosis.

scholarly journals RELATIONSHIP BETWEEN RNA SYNTHESIS, CELL DIVISION, AND MORPHOLOGY OF MAMMALIAN CELLS

1966 ◽  
Vol 29 (3) ◽  
pp. 411-421 ◽  
Author(s):  
George P. Studzinski ◽  
Kay A. O. Ellem
Keyword(s):  
Cell Division ◽  
Nucleic Acids ◽  
Ribosomal Rna ◽  
Mammalian Cells ◽  
Rna Synthesis ◽  
Acid Synthesis ◽  
Cell Number ◽  
Puromycin Aminonucleoside ◽  
Cell Content ◽  
Electronic Particle Counter

Logarithmically growing HeLa cell monolayers were treated with a range of concentrations of puromycin aminonucleoside (AMS). The effects of AMS were studied by the following means: microscope examination of treated cells; enumeration of the cell number using an electronic particle counter; analyses for DNA, RNA, and protein content; incorporation of P32 and H3-thymidine into nucleic acids; and fractionation of nucleic acids by column chromatography. Taking the rate of incorporation of the isotopic precursor as a measure of nucleic acid synthesis, it was found that concentrations of the inhibitor which had a rapid effect on the rate of cell division inhibited the synthesis of all types of nucleic acids and of protein, but depressed ribosomal RNA synthesis most markedly. Lower concentrations of AMS selectively inhibited ribosomal RNA and, to a lesser extent, transfer RNA synthesis. Partial inhibition of ribosomal RNA synthesis with low doses had no effect on the rate of cell division within the period studied (3 generation times). The cell content of RNA returned to normal when the inhibitor was removed.

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