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Biomedical subjects

J Ingle

Publications and source records attributed to J Ingle.

At least 37 records · Page 2Linked to original sources
PubMed1973

The nature of polydisperse ribonucleic acid in plants.

The aggregation of ribosomal RNA species during chromatography on methylated albumin on kieselguhr was decreased from 50 to 15% by the lower salt concentrations made possible by the use of higher pH values. The polydisperse RNA was resolved into two fractions. About 50% was eluted with the rRNA whereas the remainder was bound to the column, and was recovered only by solubilization of the methylated albumin. Both fractions of polydisperse RNA were similar in size range, but the bound fraction was considerably richer in AMP. No D-RNA (DNA-like RNA) peak was resolved under these conditions of column fractionation. However, the properties of the bound RNA were consistent with it containing both D-RNA and TB-RNA (tenaciously bound RNA). The relationship between these two fractions of AMP-rich RNA was considered. The bound RNA and ribosomal RNA responded differently to various treatments. The salt concentration required to elute ribosomal RNA was halved by increasing the pH of the fractionation, but the amount of bound RNA was in fact increased. Denaturation by hot urea decreased the binding of ribosomal RNA to the methylated albumin, but did not facilitate elution of bound RNA. The high affinity between the AMP-rich polydisperse RNA and the methylated albumin does not therefore appear to arise for the secondary structure conferred by the high AMP content.

Adenosine Monophosphate↗
PubMed1973

The genes for cytoplasmic ribosomal ribonucleic Acid in higher plants.

The genes for cytoplasmic ribosomal RNA are partially resolved from the bulk of the DNA by CsCl equilibrium centrifugation. Although in some plants the buoyant density of the ribosomal RNA genes is as expected from the base composition of ribosomal RNA, others show a large discrepancy which cannot be due to the presence of low G-C spacer-DNA. The cross-hybridization observed with 1.3 and 0.7 x 10(6) molecular weight ribosomal RNAs and DNA, which varies greatly with different plant species, is not due to contamination of the ribosomal RNAs, and is specific for the ribosomal DNA of each species, probably largely restricted to those sequences coding for the two stable ribosomal RNAs. The double reciprocal plot may be used for the extrapolation of saturation values only with caution, because in these cases such plots are not linear over the whole of the hybridization reaction.

Journal Article↗
PubMed1971

The molecular integrity of chloroplast ribosomal ribonucleic acid.

Instability of chloroplast rRNA has been observed with essentially all chloroplast RNA preparations. This paper describes experiments that show that, under normal conditions of preparation and fractionation, only the heavy chloroplast component (mol.wt. 1.1x10(6)) is unstable, the light chloroplast rRNA (mol.wt. 0.56x10(6)) and the cytoplasmic rRNA species (mol.wt. 1.3x10(6) and 0.70x10(6)) being stable. The stability of the 1.1x10(6)-mol. wt. molecule varies with different plant species, as also does the size and the number of fragments produced. Cleavages in three particular regions of the molecule are very frequent within the range of tissues studied. The 1.1x10(6)-mol.wt. rRNA is, however, stabilized by the presence of Mg(2+) during the preparation and fractionation of the RNA.

Calcium↗
PubMed1971

Effect of endotoxin on pyruvate kinase activity in mouse liver.

The pyruvate kinase (PK) activity of mouse liver increases after injection of endotoxin. It decreases in animals given cortisone alone and remains essentially unchanged in those given cortisone and endotoxin at the same time. CCl(4) causes an increase in liver PK activity, but neither it nor endotoxin changes the activity of muscle PK. Addition of octonoate to liver homogenates inhibits the activity of liver PK. These results suggest that the rapid depletion in liver glycogen after administration of endotoxin or CCl(4) may be related to increased PK activity. Induction of tolerance does not prevent the increase in liver PK activity in challenged animals.

Animals↗
PubMed1970

The Relationship between the Kinetics of Ribonucleic Acid Accumulation and the Morphological Development of the Fern Gametophyte, Dryopteris borreri.

Fern gametophytes were grown under blue light with and without the addition of 5-fluorouracil or 8-azaguanine, and under red light. Nucleic acids were extracted by either the detergent-chloroform or the detergent-diethylpyrocarbonate method and analyzed by polyacrylamide gel electrophoresis. No significant differences in the relative distribution of the stable RNA components accompanied the transition to biplanar growth. The RNA content per average cell decreased with growth and also varied between the cultural conditions, yet it was independent of the pattern of morphological development. The falling RNA content per average cell resulted from a progressive reduction of the RNA content of the apical cell, as determined histochemically. Since filamentous growth occurred by division of this apical cell, the rate of cell division was independent of the RNA content of the dividing cell.

Journal Article↗
PubMed1968

Nucleic acid and protein synthesis associated with the induction of nitrate reductase activity in radish cotyledons.

1. RNA and protein synthesis was studied during the incubation of excised radish cotyledons in nitrate, conditions that induced nitrate reductase activity in the tissue. 2. Synthesis of total RNA and protein, as measured by the incorporation of radioactive precursor, was significantly stimulated in the presence of nitrate (compared with chloride control), but was decreased in the presence of ammonium nitrate, which induced higher enzyme activity. 3. Synthesis of RNA and protein was required for induction of enzyme activity, as determined by using the inhibitors actinomycin D, puromycin and cycloheximide. 4. On the basis of 5-fluorouracil inhibition, the synthesis of only DNA-like RNA was required for induction, but no differences, either quantitative or qualitative, were observed in DNA-like RNA synthesis in the presence or absence of induction. 5. A 100-fold purification of the nitrate reductase activity showed no increase in nitrate reductase protein, nor any increased incorporation of radioactive precursor into nitrate reductase protein in the induced versus the control system. Such results suggested that the protein synthesis required for induction may be for a protein other than nitrate reductase.

Carbon Isotopes↗
PubMed1968

The effect of light and inhibitors on chloroplast and cytoplasmic RNA synthesis.

Chloroplast RNA is synthesized in dark-grown radish cotyledons at about one-third the rate of that in the light. The synthesis, however, continues for longer in the dark and the percentage of chloroplast RNA can approach that in light-grown tissue. Light stimulates the synthesis and accumulation of both cytoplasmic and chloroplast RNA, but shows a 4-fold greater stimulation of the chloroplast RNA. Chloramphenicol, streptomycin and cycloheximide inhibit the synthesis of chloroplast RNA with little effect on cytoplasmic RNA. 5-Fluorouracil inhibits the synthesis of cytoplasmic more than chloroplast RNA. Synthesis of the 0.56 x 10(6) mol wt chloroplast RNA is inhibited much less than the other ribosomal RNA components by actinomycin D.

Antimetabolites↗
PubMed1968

The induction of biplanar growth in fern gametophytes in the presence of RNA base analogues.

The RNA base analogues, 5-fluorouracil, 2-thiouracil, and 8-azaguanine, inhibit the growth of Dryopteris borreri, but do not prevent the transition from filamentous to biplanar growth. Transition, which occurs only when the filament has developed to 4 or 5 cells, may be considerably delayed, due to inhibition of filamentous growth, but it always occurs when the critical cell number of the filament is reached. Furthermore, the inhibitors show only a marginal differential effect on biplanar compared to filamentous growth when the growth rates are determined from kinetic studies. It is suggested that the selective effects previously reported may result from the experimental techniques used, coupled with the actual growth characteristics of the gametophyte.

Journal Article↗
PubMed1968

Synthesis and Stability of Chloroplast Ribosomal-RNA's.

The chloroplast ribosomal-RNAs (1.1 x 10(6) and 0.56 x 10(6) mol wt) are synthesized in the normal ratio of 2:1. The non-ribosomal distribution observed after extraction and fractionation results from the lability of the 1.1 x 10(6) component, and a correction for this breakdown can be applied in certain cases. Newly synthesized 1.1 x 10(6) RNA is more stable than the older accumulated 1.1 x 10(6) RNA. Accumulation of the chloroplast RNA during growth of radish cotyledons occurs at a later time than the accumulation of cytoplasmic RNA, and its turnover is much less than that of the cytoplasmic ribosomal-RNA.

Journal Article↗