INCORPORATION OF P32 INTO RIBONUCLEIC ACID OF RUSTED WHEAT LEAVES

1961 ◽  
Vol 39 (2) ◽  
pp. 263-267 ◽  
Author(s):  
R. Rohringer ◽  
R. Heitefuss
Keyword(s):  
Ribonucleic Acid ◽  
Rna Synthesis ◽  
Specific Activity ◽  
Leaf Material ◽  
Resistant Reaction ◽  
Wheat Leaves ◽  
Host Parasite ◽  
Parasite Complex ◽  
Metabolic Significance

P32-labelled orthophosphate was fed to rusted and non-rusted wheat leaves. The ribonucleic acid (RNA) isolated from this material was purified and its specific activity determined. The specific activity of RNA from susceptible reacting tissue had increased 60–208% [Formula: see text] days after inoculation, but [Formula: see text] days after inoculation it was not markedly different from RNA preparations of uninoculated leaf material, indicating an increase and eventual decline in RNA synthesis of the host–parasite complex. In the resistant reaction incorporation of P32 into the RNA was unaltered by infection. The possible metabolic significance of these observations is discussed.

THE PHYSIOLOGY OF HOST-PARASITE RELATIONS: IX. FURTHER OBSERVATIONS ON THE ACCUMULATION OF RADIOACTIVE SUBSTANCES AT RUST INFECTIONS

1961 ◽  
Vol 39 (6) ◽  
pp. 1393-1407 ◽  
Author(s):  
Michael Shaw
Keyword(s):  
Specific Activity ◽  
Dry Weight ◽  
Insoluble Fraction ◽  
Pentose Phosphate ◽  
Accumulation Ratio ◽  
X Ray ◽  
Specific Activities ◽  
Leaf Segments ◽  
Wheat Leaves ◽  
Host Parasite

Wang (Can. J. Botany, 38, 635–642 (1960)) concluded that the accumulation of radioactivity observed on radioautographs at infection sites on rusted leaves fed with C14-labelled substances was 'apparent' rather than real. The ‘accumulation ratio’ is defined as the ratio of the specific activities (c.p.m./mg dry weight of intact tissue) of rust-infected to uninfected areas of infected leaves. Theoretical considerations relating to the radioautography of leaves labelled with C14 and to the measurement of ‘accumulation ratios’ by extraction of C14-labelled substances from rusted and uninfected segments of infected leaves, as well as experimental data, show that Wang's conclusion is not generally applicable.Experimentally, it was shown using polymethacrylate C14 sources that differences in distance between sources and X-ray film of the order of 100 μ had no effect on the intensity of autoradiographs. Rust-infected leaves, fed with radioactive glucose, were radiographed between X-ray plates. Localization of radioactivity at infection sites was observed on both ‘dorsal’ and ‘ventral’ radiographs, indicating a real accumulation per unit area. Ventral were more radioactive than dorsal surfaces. The main development of the fungus occurred on the former. Radioautography revealed that C14 from glucose-1-C14, glucose-6-C14, and uniformly labelled glucose fed to excised wheat leaves became localized at 10-day-old rust infections in 2 hours. ‘Accumulation ratios’ calculated from the specific activity of leaf segments remained close to 1.0 for at least 6 hours after introduction of the tracer, but increased to more than 2 after 24 hours. When ‘accumulation ratios’ were calculated from the specific activities of individual pustules (excised with a punch 1 mm in diameter) and interpustular disks, values greater than 1 were observed in 2 hours, thus confirming the results of autoradiography. Differences between the ‘accumulation ratios’ observed with glucose-6-C14 and glucose-1-C14 were consistent with an increased role of the pentose phosphate pathway at infection sites. Incorporation of C14 from uniformly labelled glucose into the alcohol-insoluble fraction of rusted leaf segments was 2.5-fold that in uninfected segments in 6 hours and 3.65-fold in 24 hours. The humin formed during hydrochloric acid hydrolysis accounted for approximately 50% of the activity of the alcohol-insoluble material. The ‘accumulation ratio’ for the alcohol-soluble material was only 1.56 after 24 hours.All the results support the view (Shaw and Samborski, Can. J. Botany, 34, 389–405 (1956)) that there is a quantitative, metabolically dependent accumulation of C14 from radioactive glucose at vigorous rust infections. The relative roles of fungus and host in this process are discussed briefly.

INCORPORATION OF CYTIDINE-H3 INTO THE PRIMARY LEAF OF WHEAT FOLLOWING INFECTION WITH PUCCINIA RECONDITA ROB. EX DESM.

1963 ◽  
Vol 41 (10) ◽  
pp. 1501-1508 ◽  
Author(s):  
J. Nielsen ◽  
R. Rohringer
Keyword(s):  
Host Cell ◽  
Ribonucleic Acid ◽  
Host Tissue ◽  
Host Cells ◽  
Puccinia Recondita ◽  
Infected Leaf ◽  
Cell Nuclei ◽  
Short Term ◽  
Wheat Leaves ◽  
Host Parasite

In short-term experiments, cytidine-H3 was fed to rusted and healthy areas of wheat leaves. The incorporated activity, presumably residing in ribonucleic acid, was detected by microautoradiographic methods. Most of the label was found to be incorporated in host cell nuclei. Little incorporation occurred in extranuclear structures of host cells, including chloroplasts. Very long autoradiographic exposure times failed to reveal any incorporation into the fungus.Host cells in infected leaf areas contained considerably less label in their nuclei and cytoplasm than those in cells further from the site of infection. This effect of the fungus extended over some distance into uninvaded host tissue, but not beyond 100 μ from the periphery of the mycelium. The decreased cytidine incorporation in the affected host tissue is not caused by possible changes in pool size of endogenous cytidine. The significance of these results for the host–parasite interaction is briefly discussed.

scholarly journals Isotopic Labeling of Messenger and Stable Ribonucleic Acid and The Specific Activity of Newly Synthesized Ribonucleic Acid

1969 ◽  
Vol 244 (5) ◽  
pp. 1137
Author(s):  
N Mantel ◽  
R M Winslow ◽  
R A Lazzarini
Keyword(s):  
Ribonucleic Acid ◽  
Specific Activity ◽  
Isotopic Labeling

scholarly journals Ribonucleic Acid Biosynthesis in Human Leukocytes

Blood ◽  
1966 ◽  
Vol 28 (2) ◽  
pp. 188-200 ◽  
Author(s):  
MARTIN J. CLINE
Keyword(s):  
Density Gradient ◽  
Ribonucleic Acid ◽  
Turnover Rate ◽  
Rna Synthesis ◽  
Gradient Analysis ◽  
Sucrose Density Gradient ◽  
Acid Biosynthesis ◽  
Total Load ◽  
Human Leukocytes ◽  
Particle Ingestion

Abstract Phagocytosis has profound effects on several aspects of the RNA metabolism of human leukocytes. The major changes induced by particle ingestion appear to be (1) an increased uptake of pyrimidine precursors from the suspending medium, (2) a contraction in the size of the nucleotide pool, (3) an accelerated rate of destruction of preexisting RNA, and (4) an increased rate of RNA synthesis. Sucrose density gradient analysis of the newly synthesized RNA suggests that several classes of RNA are involved in this process. The increased turnover rate of the nucleotide pool and of the cellular RNA of the leukocyte is proportional, within limits, to the total load of ingested particles.

METABOLISM OF AROMATIC COMPOUNDS IN HEALTHY AND RUST-INFECTED PRIMARY LEAVES OF WHEAT: II. STUDIES WITH L-PHENYLALANINE-U-14C, L-TYROSINE-U-14C, AND FERULATE-U-14C

1967 ◽  
Vol 45 (11) ◽  
pp. 2137-2153 ◽  
Author(s):  
A. Fuchs ◽  
R. Rohringer ◽  
D. J. Samborski
Keyword(s):  
Amino Acids ◽  
Stem Rust ◽  
Aromatic Compounds ◽  
The Other ◽  
Major Portion ◽  
Insoluble Residue ◽  
Resistant Reaction ◽  
Wheat Leaves

Wheat leaves infected with stem rust, especially those of susceptible plants, contained more phenylalanine and tyrosine than healthy leaves. The utilization of phenylalanine was increased in both the susceptible and resistant reaction, but the utilization of tyrosine was increased only in the susceptible reaction. No evidence of interconversion of these amino acids was obtained.In n-butanol extracts, which contained glycosides, many constituents were labelled after feeding of L-phenylalanine-U-14C. Most of the n-butanol extractives from resistant-reacting leaves contained more label than those from susceptible-reacting leaves or from healthy leaves. However, one of the n-butanol extractives from susceptible-reacting leaves was 5–10 times as active as that isolated from the other tissues.With L-phenylalanine-U-14C and ferulate-U-14C as precursors, more activity was recovered in insoluble than in soluble esters (of ferulate and p-coumarate). With L-tyrosine-U-14C as precursor, the reverse was observed. After infection, the proportion of label in insoluble esters increased more in resistant leaves than it did in susceptible leaves, regardless of the precursor used.A major portion of the activity from these precursors was recovered in the insoluble residue that contained protein and other polymers. In the experiment with L-phenylalanine-U-14C, this residue was fractionated into protein and non-hydrolyzable material. Susceptible-reacting leaves contained equal amounts of activity in these fractions, while resistant-reacting leaves incorporated 2.5 times as much activity into the non-hydrolyzable material as into protein.

Hormone-induced differentiation of antheridial branches in Achlya ambisexualis: dependence on ribonucleic acid synthesis

1974 ◽  
Vol 20 (7) ◽  
pp. 977-980 ◽  
Author(s):  
David K. Horowitz ◽  
Peter J. Russell
Keyword(s):  
Sexual Differentiation ◽  
Ribonucleic Acid ◽  
Rna Synthesis ◽  
Actinomycin D ◽  
Steroid Hormone ◽  
Acid Synthesis ◽  
Aquatic Fungus ◽  
Induced Differentiation ◽  
Sexual Steroid ◽  
Achlya Ambisexualis

Sexual differentiation in male strains of the aquatic fungus Achlya ambisexualis Raper is induced by antheridiol, a sexual steroid hormone secreted by female strains. Antheridiol-induced initiation of the morphologically distinct antheridial branches in male Achlya is completely prevented when DNA-dependent RNA synthesis is inhibited by actinomycin D. In addition antheridial branch elongation is inhibited to a degree proportional to the concentration of actinomycin D added. Thus, evidence indicates that RNA synthesis is required for antheridiol-induced initiation of antheridial branching and that continued RNA synthesis is required for elongation of antheridial branches.

METABOLISM OF LEPTOSPIRES: II. THE ACTION OF 8-AZAGUANINE

1967 ◽  
Vol 13 (12) ◽  
pp. 1621-1629 ◽  
Author(s):  
Russell C. Johnson ◽  
Palmer Rogers
Keyword(s):  
Nucleic Acids ◽  
Ribonucleic Acid ◽  
Rna Synthesis ◽  
Inhibitory Effect ◽  
Relative Increase ◽  
Purine Biosynthesis ◽  
Low Concentrations

Both the pathogen Leptospira pomona and the saprophyte L. biflexa Patoc I can convert exogenous adenine, guanine, and 8-azaguanine to the corresponding nucleotide and incorporate them into nucleic acids. L. pomona is inhibited by low concentrations of 8-azaguanine (50 μg/ml) and this inhibition is associated with less than a 5% replacement of the ribonucleic acid (RNA) guanine residues by the analogue. Guanine possessed the highest activity for antagonizing the inhibitory effect of 8-azaguanine. The biosynthetic process of L. pomona most affected by the analogue was a relative increase in RNA synthesis. The analogue-resistant L. biflexa incorporated 1/10 as much 8-azaguanine as L. pomona. The higher rate of purine biosynthesis, in addition to the lesser amount of 8-azaguanine incorporated, may account for the analogue resistance of L. biflexa.

The appearance and quantitation of cytoplasmic ribonucleic acid in the early chick embryo

Development ◽  
1972 ◽  
Vol 28 (2) ◽  
pp. 367-384
Author(s):  
C. C. Wylie
Keyword(s):  
Chick Embryo ◽  
Ribosomal Rna ◽  
Rna Synthesis ◽  
Specific Activity ◽  
Cell Number ◽  
Present Knowledge ◽  
Precursor Pool ◽  
Cytoplasmic Rna ◽  
Labelling Experiment ◽  
Neurula Stage

This paper seeks to extend our knowledge about RNA synthesis in early embryogenesis to the domestic fowl, Gallus domesticus. Using this species for research, apart from increasing our knowledge of higher vertebrate embryology, has certain advantages such as rapid uptake of isotopic precursors and ease of microdissection in culture. The following results are presented: (1) The cell number in the whole chick embryos is shown to be increasing logarithmically between the time of laying and the early neurula stage; with a doubling time of 7·4 h. (2) The onset of ribosomal RNA synthesis has been shown to be during mid-cleavage of the chick embryo, while development is taking place in the oviduct and uterus of the mother. (3) In a cumulative labelling experiment, embryos were labelled at the unincubated-egg stage, allowed to develop to various morphological stages up to neurulation, and their cytoplasmic RNA prepared and analysed by gel electrophoresis. (4) The specific activity of the precursor pool for RNA synthesis was measured at several stages, using the same labelling conditions, and the results were used to quantitate the RNA synthesis from the incorporated radioactivity. (5) Using these techniques, it was found that newly synthesized cytoplasmic RNA accumulates steadily in the whole chick embryo, reaching a level of 104 μg by the early neurula stage. On a per cell basis, however, the amount of newly synthesized cytoplasmic RNA seems to decrease slightly. These findings are discussed in the light of present knowledge about embryos of other vertebrates and certain invertebrates.

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