Enhanced Deoxyribonucleic Acid Polymerase Activity of Chromatin from Soybean Hypocotyls Treated with 2,4-Dichlorophenoxyacetic Acid

Leffler, H. R.; O’Brien, Timothy J.; Cherry, Joe H.

doi:10.1104/pp.48.1.43

Cited by 24 publications

(3 citation statements)

References 19 publications

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“…In soybean, the greatest RNA increase occurs in the ribosomal fraction (4,12). Increases in DNA content in cowpea hypocotyls following 2,4-D treatment indica:e an increase in cell division, as observed in soybean (10,12 (14) and RNA polymerase (21) in chromatin isolated from 2, 4-D-treated soybean hypocotyls increased over comparable activity in untreated controls. We have shown that at least one key enzyme in the synthesis of the pyrimidine nucleic acid precursors also shows enhanced activity following seedling treatment with 2,4-D.…”

Section: Resultsmentioning

confidence: 84%

Asparate Transcarbamylase Activity in Etiolated Cowpea Hypocotyls Treated with 2,4-Dichlorophenoxyacetic Acid

Johnson¹,

Niblett²,

Shively³

1973

Plant Physiol.

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Treating etiolated cowpea (Vigna unguiculata) seedlings with 2,4-dichlorophenoxyacetic acid resulted in 2.5-, 3.9-, and 6.5-fold increases in DNA, soluble protein, and RNA, respectively, over untreated controls 84 hours after treatment. Aspartate transcarbamylase activity increased within 12 hours after treatment, and by 84 hours it was almost 12-fold greater than that in the untreated controls. During that time, activity in untreated controls dropped 60%. The assay used '4C-aspartate, which was then separated from the "4C-ureidosuccinate product by Dowex 50 (H+ form) column chromatography. Thin layer chromatography of the reaction product indicated that most of the carbamyl-phosphate-dependent radioactivlity cochromatographed with ureidosuccinate. The reaction has a pH optimum near 10.0 and is inhibited by uridine 5'-phosphate and succinate. The data suggest that aspartate transcarbamylase is important in pyrimidine biosynthesis in 2,4-dichlorophenoxyacetic acid-treated seedlings.Aspartate transcarbamylase (carbamoylphosphate: L-aspartate carbamoyltransferase, EC 2.1.3.2) catalyzes the first reaction unique to pyrimidine biosynthesis: aspartic acid + carbamyl phosphate -* carbamyl aspartate (ureidosuccinate) + P,. This enzyme is regulated by feedback inhibition in several microorganisms (22). The pathway of synthesis of pyrimidine nucleotides in higher plants appears similar to that reported for microorganisms (26). Aspartate transcarbamylase from higher plants is a potential site for feedback regulation of the pathway, as it is inhibited strongly by UMP and somewhat by certain other pyrimidine nucleotides (19,20,28,29 cant increase in the activity of this enzyme should occur following 2, 4-D treatment. MATERIALS AND METHODSPlant Material. Etiolated cowpea (Vigna unguiculata L. Walp cv. Early Ramshorn) seedlings were grown in the dark at 29 to 30 C and 85% relative humidity. Seeds with unbroken seedcoats (15) were surface-sterilized 2 to 3 min in 0.5% NaOCI and planted in trays of moist vermiculite.Five days after planting, seedlings were sprayed to run-off with a 2,4-D solution (1 mg/ml) containing 4% ethanol. Controls received a comparable 4% ethanol spray. Hypocotyls were harvested at 12-hr intervals and stored at -18 C until extracted.Tissue Extraction. Frozen tissues were ground with a cold mortar and pestle in cold (3 C) 0.1 M ethanolamine-HCl buffer, pH 10.0. Five or six hypocotyls were ground per treatment, in 2 ml of buffer per g fresh weight. Extracts were centrifuged at 37,000g and 3 C for 15 min. Aliquots of the supernatant fluid were frozen for later determination of RNA, DNA, and soluble protein. Another portion was dialyzed for 16 to 20 hr in cold 0.05 M ethanolamine-HCl buffer, pH 10.0, for use in enzyme assays.Aspartate Transcarbamylase Assay. Four test tubes containing 0.5 ml of dialyzed enzyme and 0.25 ml of 0.05 M ethanolamine-HCl (pH 10.0) buffer were prepared for each treatment and stored at 3 C until 3 to 8 min before assay, when the tubes were shaken in a water bath at 37 C. The ...

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Section: Resultsmentioning

confidence: 84%

Asparate Transcarbamylase Activity in Etiolated Cowpea Hypocotyls Treated with 2,4-Dichlorophenoxyacetic Acid

Johnson¹,

Niblett²,

Shively³

1973

Plant Physiol.

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“…The reaction mixtures were incubated at 37 C for 60 min with R. meliloti extracts and 30 min with alfalfa bacteroid extracts. The reactions were terminated by immediate chilling on ice and the addition of an equal amount (v/v) of 10% trichloroacetic acid-2% pyrophosphate solution (10). The acid-insoluble product was collected on glass fiber disks (Whatman GF/A) and washed with 2 x 2 ml of 5% trichloroacetic acid-1% pyrophosphate solution and 10 x 2 ml of ice-cold distilled H20.…”

Section: Methodsmentioning

confidence: 99%

Comparison of DNA Polymerase of Rhizobium meliloti and Alfalfa Bacteroids

Paau¹,

Cowles²

1975

Plant Physiol.

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“…Bollum (1975) has reported that in most rapidly growing eukaryotie tissues, over 95% of the total DNA polymerase activity may be attributed to DNA polymerase-ci (6-8 S moleeule) and DNA polymerase-/3 (3.4 S moleeule). Although several researchers (Stout and Arens 1970, Leffler et al 1971, Dunham and Cherry 1973a, Robinson and Bryant 1975 have reported the presence of soluble and chromatin bound DNA polymerases in plants, detailed enzyme eharacterization as to molecular weight and reaction properties remain to be elueidated. Preliminary evidenee based primarily on moleeular weight studies in tobaeeo tissue cultures (Srivastava and Grace 1974) and sugar beet (Tymonko and Dunham 1975), has indicated the presence of multiple DNA polymerase activities in plant tissue.…”

Section: Introductionmentioning

confidence: 99%

Evidence for DNA Polymerase‐α and ‐β Activity in Sugar Beet

Tymonko

Dunham

1977

Physiologia Plantarum

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DNA polymerase preparations from incubated sugar beet (Beta vulgaris) root tissue exhibited multiple activities following DEAE‐cellulose chromatography and glycerol density gradient centrifugation (600‐fold purification). The two major polymerase activities eluted from DEAE‐cellulose differed in heat lability, pH and Mg2+ optima, and in response to ethanol, p‐hydroxymercuribenzoate, and N‐ethylmaleimide. Further purification by glycerol gradient centrifugation indicated the presence of a low molecular weight molecule (3.4 S), heterogeneous larger molecules (6.2, 6.8 S), and apparent aggregates (11–11.5 S). This investigation indicates similarities between sugar beet polymerases and the small (β) and large (α) molecular weight polymerases from mammalian systems.

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Enhanced Deoxyribonucleic Acid Polymerase Activity of Chromatin from Soybean Hypocotyls Treated with 2,4-Dichlorophenoxyacetic Acid

Cited by 24 publications

References 19 publications

Asparate Transcarbamylase Activity in Etiolated Cowpea Hypocotyls Treated with 2,4-Dichlorophenoxyacetic Acid

Asparate Transcarbamylase Activity in Etiolated Cowpea Hypocotyls Treated with 2,4-Dichlorophenoxyacetic Acid

Comparison of DNA Polymerase of Rhizobium meliloti and Alfalfa Bacteroids

Evidence for DNA Polymerase‐α and ‐β Activity in Sugar Beet

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