The effect of aerated hydration on DNA synthesis in embryos of Brassica oleracea L.

1993 ◽  
Vol 3 (3) ◽  
pp. 195-199 ◽  
Author(s):  
J. M. Thornton ◽  
A. R. S. Collins ◽  
A. A. Powell
Keyword(s):  
Dna Damage ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Brassica Oleracea ◽  
Thymidine Incorporation ◽  
Recovery Process ◽  
Time Difference ◽  
Brussels Sprouts ◽  
Brassica Oleracea L

AbstractAgeing causes a delay in the onset of DNA replication in seeds. Aerated hydration for 8 h, a treatment to invigorate seeds, resulted in a reduction of about 12 h in the time difference in the onset of DNA synthesis between unaged and aged embryos of brassica seed. This effect is consistent with a recovery process occurring during aerated hydration of the seed involving the repair of accumulated DNA damage. The occurrence of hydroxyurea-resistant 3H-thymidine incorporation in aged Brussels sprouts embryos during the period 16–32 h from the start of hydration supports this interpretation.

Timing of nucleolar DNA replication in Amoeba proteus

1976 ◽  
Vol 22 (3) ◽  
pp. 521-530
Author(s):  
I. Minassian ◽  
L.G. Bell
Keyword(s):  
Electron Microscope ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Central Region ◽  
Thymidine Incorporation ◽  
Tritiated Thymidine ◽  
Amoeba Proteus ◽  
Electron Microscope Autoradiography ◽  
Microscope Autoradiography ◽  
G2 Phase

Light- and electron-microscope autoradiography have been used to follow the incorporation of [3H]thymidine at different stages during the interphase of synchronously growing populations of Amoeba proteus. Two main patterns were found for tritiated thymidine incorporation, i.e. DNA synthesis. The major incorporation was in the central region of the nucleus, but a lesser degree of incorporation occurred in the nucleolar region. The bulk of this nucleolar DNA was found to be late replicating, i.e. it replicated during the G2 phase.

scholarly journals Stwl Modifies Chromatin Compaction and Is Required to Maintain DNA Integrity in the Presence of Perturbed DNA Replication

2009 ◽  
Vol 20 (3) ◽  
pp. 983-994 ◽  
Author(s):  
Xia Yi ◽  
Hilda I. de Vries ◽  
Katarzyna Siudeja ◽  
Anil Rana ◽  
Willy Lemstra ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Replication Stress ◽  
Epigenetic Mechanism ◽  
Dna Integrity ◽  
Silent Chromatin ◽  
Chromatin Compaction ◽  
Cycle Arrest ◽  
Dna Replication Stress

Hydroxyurea, a well-known DNA replication inhibitor, induces cell cycle arrest and intact checkpoint functions are required to survive DNA replication stress induced by this genotoxic agent. Perturbed DNA synthesis also results in elevated levels of DNA damage. It is unclear how organisms prevent accumulation of this type of DNA damage that coincides with hampered DNA synthesis. Here, we report the identification of stonewall (stwl) as a novel hydroxyurea-hypersensitive mutant. We demonstrate that Stwl is required to prevent accumulation of DNA damage induced by hydroxyurea; yet, Stwl is not involved in S/M checkpoint regulation. We show that Stwl is a heterochromatin-associated protein with transcription-repressing capacities. In stwl mutants, levels of trimethylated H3K27 and H3K9 (two hallmarks of silent chromatin) are decreased. Our data provide evidence for a Stwl-dependent epigenetic mechanism that is involved in the maintenance of the normal balance between euchromatin and heterochromatin and that is required to prevent accumulation of DNA damage in the presence of DNA replication stress.

Microspore embryogenesis and plant regeneration in Brussels sprouts (Brassica oleracea L. var. gemmifera)

2015 ◽  
Vol 191 ◽  
pp. 31-37 ◽  
Author(s):  
Aisong Zeng ◽  
Yuanyuan Yan ◽  
Jiyong Yan ◽  
Lixiao Song ◽  
Bing Gao ◽  
...  
Keyword(s):  
Plant Regeneration ◽  
Brassica Oleracea ◽  
Microspore Embryogenesis ◽  
Brussels Sprouts ◽  
Brassica Oleracea L

Cole crop yield response to reduced nitrogen rates

1999 ◽  
Vol 79 (1) ◽  
pp. 149-151 ◽  
Author(s):  
K. R. Sanderson ◽  
J. A. Ivany
Keyword(s):  
Brassica Oleracea ◽  
Yield Response ◽  
Marketable Yield ◽  
Brussels Sprouts ◽  
Control Banding ◽  
Reduced Nitrogen ◽  
N Rates ◽  
Nitrogen Rates ◽  
Cole Crop ◽  
Brassica Oleracea L

Response of cabbage (Brassica oleracea L. var. capitata), Brussels sprouts (Brassica oleracea var. gemmifera) and broccoli (Brassica oleracea L. var italica) to reduced N rates was studied over 4 yr. Treatments were application methods, broadcast, split and banded with two rates of N; 120 and 90 kg ha−1 plus a control of 150 kg ha−1 broadcast N. Marketable yield was lower by 15, 23, and 13%, respectively, compared to the control. Banding lowered yield of cabbage and broccoli. The lower N rate had the lowest yield in all crops. Leaf N concentration varied with N rate. Key words: Broccoli, Brussels sprouts, cabbage, reduced nitrogen, yield

The Inifiation, Maintenance and Termination DNA Synthesis: A Study of Nuclear DNA Replication Using Amoeba Proteus As a Cell Model

1971 ◽  
Vol 9 (1) ◽  
pp. 1-21
Author(s):  
M. J. ORD
Keyword(s):  
Dna Replication ◽  
Dna Synthesis ◽  
Nuclear Dna ◽  
Thymidine Incorporation ◽  
Cell Model ◽  
Amoeba Proteus ◽  
Early Prophase ◽  
Precursor Pool ◽  
Endogenous Precursor ◽  
The Individual

By means of the nuclear transfer technique for amoeba, combinations of nuclei and cytoplasma from all parts of the cell cycle were available for examining the individual roles of the nucleus and cytoplasm in nuclear DNA replication. Neither S-phase nor division sphere cytoplasm proved capable of initiating a new round of nuclear DNA synthesis in the G2 nucleus. There was some indication that G2 nuclei which were transferred into early prophase cells, i.e. before the formation of a regular division sphere, did incorporate more [3H]thymidine than control G2 nuclei. Positive proof of the induction of DNA synthesis in ‘immature’ nuclei was observed in only two cases. When young G2 nuclei were transplanted into late G2 amoebae, the addition of the donor nucleus generally resulted in the older nucleus being held in a late G2 phase until the younger nucleus passed through its G2. Division of 90% of heterophasic homokaryons was synchronous, with a subsequent synchrony of DNA synthesis. A study of variance in [3H]thymidine incorporation by S nuclei sharing the same cytoplasm - using binucleate, trinucleate and multinucleate homokaryons - showed that nuclei through the peak-S period synthesized DNA at approximately similar rates. The large differences in [3H]thymidine incorporation by nuclei of amoebae of equal age appear due to differences in endogenous precursor pools. These would vary both with differences in food intake and with the draining of remote precursor pools for simultaneous cellular activities, particularly RNA synthesis. When sharing the same cytoplasm nuclei in peak S incorporated similar amounts of [3H]thymidine. Though cytoplasm did not influence the progress of DNA replication by a nucleus, it did influence the use of exogenous [3H]thymidine by the cell, and in so doing caused much of the variation observed in the labelling of nuclei during S. Nuclei sharing the same cytoplasm, and so subject to the same precursor pool changes, incorporated similar amounts of exogenous thymidine. Once DNA synthesis had been initiated it continued to completion regardless of the cytoplasm which surrounded it. Thus neither the maintenance nor termination of DNA synthesis required a special cytoplasmic state.

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