Impurity in RNA Preparations which Inactivates RNase Inhibitor and Increases Alkaline RNase Activity.

Extracts from primary leaves of Lee wheat were prepared at various days following inoculation with races of leaf rust and tested for ribonuclease (RNase) activity. As early as 24 hours after inoculation there was a marked increase in the specific activity of the enzyme in extracts of rusted host tissues. A further increase in activity was observed during later stages of infection, with the susceptible and resistant reacting tissue differing only in the degree of their response. Extracts from noninoculated control leaves exhibited a constant RNase activity throughout the period of observation. The germination medium and extracts from germinating uredospores contained comparatively little RNase activity. No direct evidence was obtained either for the possible release of the enzyme from particulate cellular fractions of the host tissue as a result of infection or for the removal of an RNase inhibitor in the host tissue responding to infection.

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STUDIES ON THE FUNCTION OF INTRACELLULAR RIBONUCLEASES

The Journal of Cell Biology ◽

10.1083/jcb.8.3.665 ◽

1960 ◽

Vol 8 (3) ◽

pp. 665-673 ◽

Cited By ~ 26

Author(s):

Jay S. Roth

Keyword(s):

Enzyme Activity ◽

Biological Activity ◽

Rat Liver ◽

Liver Microsomes ◽

Rnase Activity ◽

Rat Liver Microsomes ◽

Rnase Inhibitor ◽

Normal Constituent ◽

Liver Ribosomes

Attempts have been made to prepare rat liver microsomes and ribosomes free of RNase activity. Washing of microsomes with a large number of reagents, as well as preparation of microsomes by homogenizing the liver in the presence of a variety of reagents chosen to remove or inhibit RNase activity, failed to abolish completely the enzyme activity. However, when rat liver was homogenized in the presence of optimal concentrations of ATP the microsomes subsequently obtained showed no RNase activity. The composition of such microsomes was compared to controls prepared without the use of ATP. Preparation of microsomes with the use of ATP apparently repressed but did not remove the RNase activity for, when such microsomes were treated with 1 per cent deoxycholate to obtain ribosomes, the latter exhibited normal RNase activity. A possible explanation for these results based on several experiments is given. The incorporation of C14 of L-leucine-C14 into control and ATP-treated microsomes was measured. Repression of RNase activity by use of ATP or with RNase inhibitor, significantly reduced the incorporation. As a result of these and other experiments it is tentatively concluded that an alkaline RNase is a normal constituent of rat liver ribosomes and plays a role in the biological activity of these particles.

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THE EFFECT OF A SINGLE LARGE DOSE OF 9α-FLUOROPREDNISOLONE ON NUCLEODEPOLYMERASE ACTIVITY AND NUCLEIC ACID CONTENT OF THE RAT THYMUS

Acta Endocrinologica ◽

10.1530/acta.0.0490138 ◽

1965 ◽

Vol 49 (1) ◽

pp. 138-144 ◽

Cited By ~ 23

Author(s):

Peter H. Wiernik ◽

Robert M. MacLeod

Keyword(s):

Body Weight ◽

Nucleic Acid ◽

Large Dose ◽

Rnase Activity ◽

Male Rats ◽

Nucleic Acid Content ◽

Post Injection ◽

Dnase Ii ◽

Rnase Inhibitor ◽

Rna Concentration

ABSTRACT The injection of male rats with 25 mg 9α-fluoroprednisolone/kg body weight caused a 29 % decrease in thymus RNA concentration 20 hours after injection. At this time, acid RNase activity had increased to more than twice control values. Alkaline RNase activity in whole thymus homogenates were increased 4 hours post injection. The removal of an alkaline RNase inhibitor from thymus homogenates greatly altered the response to steroid. Control values of alkaline RNase activity were 6 fold greater in homogenates from which the inhibitor had been removed. No effect of steroid on alkaline RNase activity was detected in homogenates from which the inhibitor was removed. DNase II activity was significantly elevated 2 hours post injection and reached a peak 2 hours later. No decrease in DNA concentration of thymus homogenates could be demonstrated.

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Modulation of cystolic RNase activity by endogenous RNase inhibitor in rat vaginal epithelial cells on estradiol administration

FEBS Letters ◽

10.1016/0014-5793(94)80029-4 ◽

1994 ◽

Vol 348 (2) ◽

pp. 221-221

Keyword(s):

Epithelial Cells ◽

Rnase Activity ◽

Rnase Inhibitor ◽

Vaginal Epithelial Cells

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Identification of lysine residues in the binding domain of ribonuclease A for the RNase inhibitor from human placenta.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(19)68364-x ◽

1982 ◽

Vol 257 (1) ◽

pp. 316-321

Author(s):

P. Blackburn ◽

J.G. Gavilanes

Keyword(s):

Human Placenta ◽

Ribonuclease A ◽

Binding Domain ◽

Rnase Inhibitor ◽

Lysine Residues

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STUDIES ON THE FUNCTION OF INTRACELLULAR RIBONUCLEASES

The Journal of Cell Biology ◽

10.1083/jcb.29.3.395 ◽

1966 ◽

Vol 29 (3) ◽

pp. 395-403 ◽

Cited By ~ 26

Author(s):

Takeshi Utsunomiya ◽

Jay S. Roth

Keyword(s):

Natural Products ◽

Sodium Chloride ◽

Rat Liver ◽

Messenger Rna ◽

Rnase Activity ◽

Optimum Ph ◽

Normal Rat ◽

Pancreatic Rnase ◽

The Stability ◽

Normal Constituent

The RNase activity and properties of ribosome and polysome preparations from normal rat liver and some hepatomas have been examined. Polysome and ribosome preparations from the Novikoff, McCoy MDAB, and Dunning hepatomas had considerably higher specific RNase activity than corresponding preparations from normal rat liver, Novikoff ascites, or Morris 5123 hepatomas. The optimum pH of the RNase was approximately 8.5 for all samples tested, and the samples showed no evidence of latent RNase activity when treated with 3 M sodium chloride, EDTA, urea, or p-chloromercuribenzenesulfonic acid. The RNase activity appeared to be associated principally with breakdown products and/or subunits smaller than 80S. In the presence of Mg++ ions, subunits could reaggregate to form monomer ribosomes indistinguishable from the natural products, but some of the reassociated ribosomes could contain RNase activity which had been bound to the smaller particles. Similar results were obtained with spermine. In the hepatomas, evidence was obtained for the preexistence of considerable amounts of the smaller, RNase-containing subunits in the cell. When a small amount of crystalline bovine pancreatic RNase was added to partly dissociated ribosomes, the RNase was found only in association with the smaller subunits, and little or no enzyme was taken up by ribosomes or polysomes. The results have led to the conclusion that RNase is not a normal constituent of the ribosome or polysome, but that RNase may become associated with these particulates if dissociation and reassociation take place. Some implications of these findings for the stability of messenger RNA and for the mechanism of its breakdown are discussed.

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