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T J Guilfoyle

Publications and source records attributed to T J Guilfoyle.

59 records · Page 4Linked to original sources
PubMed1975

Isolation and Properties of Nuclei from Control and Auxin-treated Soybean Hypocotyl.

A quick procedure for the isolation of nuclei with good yield from soybean hypocotyl (Glycine max var. Wayne) was developed. The isolated nuclei appeared to retain their structural integrity. They were typically ellipsoidal with minima and maxima diameter of about 6 and 8 to 10 micrometers. While the nuclei were similar in size, the nucleoli were significantly larger in nuclei from auxin-treated tissue. The DNA content per nucleus was 4 +/- 1 picograms for both untreated and auxin-treated tissues. The DNA: RNA: protein ratio of isolated nuclei in untreated and auxin-treated tissues was 1: 3.1: 11 and 1: 5.4: 21.7, respectively. The purified nuclei were active in RNA synthesis; the level of RNA polymerase II activity expressed in the nuclei from untreated tissue was 50 to 60% higher than RNA polymerase. I. The nuclei from auxin-treated tissues contained about 2.5 times as much RNA polymerase I activity as nuclei from untreated tissue. The purified nuclei from both untreated and auxin-treated tissues were also active in the incorporation of (3)H-TTP into DNA.

Journal Article↗
PubMed1975

Isolation of nucleoli and localization of ribonucleic Acid polymerase I from soybean hypocotyl.

An effective method for the isolation of nucleoli from auxin-treated soybean (Glycine max, var. Wayne) hypocotyl was developed by polytron homogenization and sucrose gradient centrifugation. The nucleoli expressed only the alpha-amanitin-insensitive RNA synthetic activity. This activity chromatographed as RNA polymerase I on DEAE-cellulose. It appears that the plant nucleolus, like the animal nucleolus, is the site of localization for RNA polymerase I.

Journal Article↗
PubMed1974

Greater Length of Ribonucleic Acid Synthesized by Chromatin-bound Polymerase from Auxin-treated Soybean Hypocotyls.

An investigation has been made of the RNA synthesized by chromatin-bound RNA polymerase from soybean hypocotyls (Glycine max var. Wayne). Polymerase activity is 4- to 5-fold higher with chromatin from tissue treated with 2,4-dichlorophenoxyacetic acid, a synthetic auxin, compared to untreated tissue. Thin layer chromatography of the RNA hydrolysis products and acrylamide gel electrophoresis of the RNA synthesized by the chromatin show that increased activity induced by 2,4-dichlorophenoxyacetic acid is due primarily to the production of longer RNA chains, with only 20 to 50% increase in the number of RNA chains. The observation that 2,4-dichlorophenoxyacetic acid treatment leads to greater rates of RNA synthesis, producing longer chains in unit time, suggests that one manifestation of auxin activity is in activation of RNA polymerase I (ribosomal RNA polymerase).

Journal Article↗
PubMed1973

Increased Activity of Chromatin-bound Ribonucleic Acid Polymerase from Soybean Hypocotyl with Spermidine and High Ionic Strength.

Optimal activity of chromatin-bound RNA polymerase from soybeans is obtained with 1 mm Mn(2-), but only when high ionic strength or polyamines are included in the medium. Such inclusion does not increase the Mg(2+) activation of the polymerase, but it does lower the concentration needed for optimum activity from 10 mm to 1 mm. Mg(2-) activation is inhibited by added Mn(2+), and the inhibition is relieved by high ionic strength or spermidine. The RNA polymerase with either cation is almost entirely polymerase I at low and high ionic strength as evidenced by insensitivity to alpha-amanitin. Treatment of soybean seedlings with 2,4-dichlorophenoxyacetic acid does not change these characteristics; although the activity rises 3- to 4-fold.It is suggested that chromatin as prepared here may be a selected fraction enriched in polymerase I, which is activated by either Mg(2+) or Mn(2+), and that the Mn(2-) inhibition of activity is due to a known reaction of Mn(2-) with DNA which can be relieved by high ionic strength.

Journal Article↗