Changes in some Enzymes involved in DNA Biosynthesis following Induction of Division in Cultured Plant Cells

1973 ◽  
Vol 13 (1) ◽  
pp. 121-138
Author(s):  
JENNIFER HARLAND ◽  
J. F. JACKSON ◽  
M. M. YEOMAN
Keyword(s):  
Enzyme Activity ◽  
Cell Division ◽  
Dna Polymerase ◽  
Plant Cells ◽  
Jerusalem Artichoke ◽  
Close Correlation ◽  
Tissue Cultures ◽  
Dna Biosynthesis ◽  
Major Increase ◽  
Thymidine Monophosphate

The biosynthetic enzymes DNA polymerase, thymidine kinase (TdR kinase) and thymidine monophosphate kinase (dTMP kinase) show characteristic patterns of activity associated with cell division in synchronously dividing tissue cultures of the Jerusalem artichoke. In each case the first major increase in enzyme activity is coincident with and dependent upon DNA replication. In addition the increased activities of all 3 enzymes are not due to the activation of pre-existing enzyme or to the removal of inhibitors. A theory is advanced to account for the close correlation between DNA synthesis and the major rise in activity of the 3 enzymes.

Correlation of PCB Transformation by Plant Tissue Cultures with Their Morphology and Peroxidase Activity Changes

1999 ◽  
Vol 64 (9) ◽  
pp. 1497-1509 ◽  
Author(s):  
Petra Kučerová ◽  
Martina Macková ◽  
Ludmila Poláchová ◽  
Jiří Burkhard ◽  
Kateřina Demnerová ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Polychlorinated Biphenyls ◽  
Peroxidase Activity ◽  
Plant Tissue ◽  
Plant Cells ◽  
Tissue Cultures ◽  
Transforming Activity ◽  
Plant Tissue Cultures ◽  
Transformation Capacity

The ability of plant cells cultivated in vitro to metabolize polychlorinated biphenyls (PCBs) was correlated with the morphology of the cultures tested as models for phytoremediation studies. More differentiated cultures showed generally higher transformation capacity. The ability of plant cells to transform PCBs is connected to their viability in the presence of PCBs and their behaviour can be positively correlated with the production of intracellular and extracellular peroxidases. The cultures with high PCB-transforming activity proved to exhibit high peroxidase activity in the presence of PCBs while those with low ability to metabolize PCB showed a decrease of the enzyme activity in the presence of PCBs. Experiments with propylgallate were used to distinguish the ratio of involvement of peroxidases in PCB metabolism.

scholarly journals The Effect of Cycloheximide on Cell Division in Partially Synchronized Plant Cells

1970 ◽  
Vol 23 (3) ◽  
pp. 573 ◽  
Author(s):  
RJ Rose
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Broad Bean ◽  
Plant Cells ◽  
Jerusalem Artichoke ◽  
Root Tips ◽  
Tuber Tissue ◽  
Jerusalem Artichoke Tuber ◽  
Bean Root ◽  
Mitotic Frequency

Cycloheximide blocked cell division at interphase, prophase, prometaphase, metaphase, and telophase in Jerusalem artichoke tuber tissue. Blocking at anaphase did not occur or was very infrequent. In any cell, the location of the block depended upon the stage of the cell cycle reached at the time of cycloheximide addition. In general, cycloheximide caused similar blocks in interphase and mitosis in cells of synchronised broad bean root tips. A reduction of mitotic frequency occurred after about 8 hr in cycloheximide, indicating a reversion of chromosome coiling.

Confocal microscopy of the cytoskeleton in living plant cells following microinjection of fluorescent probes

1993 ◽  
Vol 51 ◽  
pp. 130-131
Author(s):  
Ann Cleary
Keyword(s):  
Cell Division ◽  
Fluorescent Probes ◽  
Actin Filaments ◽  
Intracellular Transport ◽  
Cell Structure ◽  
Plant Cells ◽  
Cell Plate ◽  
Cell Cortex ◽  
Living Plant ◽  
Rhodamine Phalloidin

Microinjection of fluorescent probes into living plant cells reveals new aspects of cell structure and function. Microtubules and actin filaments are dynamic components of the cytoskeleton and are involved in cell growth, division and intracellular transport. To date, cytoskeletal probes used in microinjection studies have included rhodamine-phalloidin for labelling actin filaments and fluorescently labelled animal tubulin for incorporation into microtubules. From a recent study of Tradescantia stamen hair cells it appears that actin may have a role in defining the plane of cell division. Unlike microtubules, actin is present in the cell cortex and delimits the division site throughout mitosis. Herein, I shall describe actin, its arrangement and putative role in cell plate placement, in another material, living cells of Tradescantia leaf epidermis.The epidermis is peeled from the abaxial surface of young leaves usually without disruption to cytoplasmic streaming or cell division. The peel is stuck to the base of a well slide using 0.1% polyethylenimine and bathed in a solution of 1% mannitol +/− 1 mM probenecid.

scholarly journals Activity and Accumulation of Cell Division-Promoting Phenolics in Tobacco Tissue Cultures

1991 ◽  
Vol 97 (1) ◽  
pp. 288-297 ◽  
Author(s):  
Rita A. Teutonico ◽  
Matthew W. Dudley ◽  
John D. Orr ◽  
David G. Lynn ◽  
Andrew N. Binns
Keyword(s):  
Cell Division ◽  
Tissue Cultures

scholarly journals Cell Cycle-Specific Disruption of the Preprophase Band of Microtubules in Fern Protonemata: Effects of Displacement of the Endoplasm by Centrifugation

1992 ◽  
Vol 101 (1) ◽  
pp. 93-98 ◽  
Author(s):  
TAKASHI MURATA ◽  
MASAMITSU WADA
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Plant Cells ◽  
Preprophase Band ◽  
Higher Plant ◽  
The Future ◽  
Prophase Nucleus ◽  
Original Region ◽  
Fern Protonemata

The preprophase band (PPB) of microtubules (MTs), which appears at the future site of cytokinesis prior to cell division in higher plant cells, disappears by metaphase. Recent studies have shown that displacement of the endoplasm from the PPB region by centrifugation delays the disappearance of the PPB. To study the role of the endoplasm in the cell cycle-specific disruption of the PPB, the filamentous protonemal cells of the fern Adiantum capilius-veneris L. were centrifuged twice so that the first centrifugation displaced the endoplasm from the site of the PPB and the second returned it to its original location. The endoplasm, including the nucleus of various stages of mitosis, could be returned by the second centrifugation to the original region of the PPB, which persists during mitosis in the centrifuged cells. When endoplasm with a prophase nucleus was returned to its original location, the PPB was not disrupted. When endoplasm with a prometa-phase telophase nucleus was similarly returned, the PPB was disrupted within 10 min of termination of centrifugation. In protonemal cells of Adiantum, a second PPB is often formed near the displaced nucleus after the first centrifugation. In cells in which the endoplasm was considered to have been returned to its original location at the prophase/prometaphase transition, the second PPB did not disappear even though the initial PPB was disrupted by the endoplasm. These results suggest that cell cycle-specific disruption of the PPB is regulated by some factor(s) in the endoplasm, which appears at prometaphase, i.e. the stage at which the PPB is disrupted in non-centrifuged cells.

Characterization of two telomeric DNA processing reactions in Saccharomyces cerevisiae

1988 ◽  
Vol 8 (11) ◽  
pp. 4642-4650
Author(s):  
A W Murray ◽  
T E Claus ◽  
J W Szostak
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Division ◽  
Dna Polymerase ◽  
Dna Sequences ◽  
Inverted Repeat ◽  
Telomeric Sequence ◽  
Telomeric Dna ◽  
Telomeric Sequences ◽  
Telomere Elongation

We have investigated two reactions that occur on telomeric sequences introduced into Saccharomyces cerevisiae cells by transformation. The elongation reaction added repeats of the yeast telomeric sequence C1-3A to telomeric sequences at the end of linear DNA molecules. The reaction worked on the Tetrahymena telomeric sequence C4A2 and also on the simple repeat CA. The reaction was orientation specific: it occurred only when the GT-rich strand ran 5' to 3' towards the end of the molecule. Telomere elongation occurred by non-template-directed DNA synthesis rather than any type of recombination with chromosomal telomeres, because C1-3A repeats could be added to unrelated DNA sequences between the CA-rich repeats and the terminus of the transforming DNA. The elongation reaction was very efficient, and we believe that it was responsible for maintaining an average telomere length despite incomplete replication by template-directed DNA polymerase. The resolution reaction processed a head-to-head inverted repeat of telomeric sequences into two new telomeres at a frequency of 10(-2) per cell division.

scholarly journals Unique N-glycosylation of a recombinant exo-inulinase from Kluyveromyces cicerisporus and its effect on enzymatic activity and thermostability

2019 ◽  
Vol 13 (1) ◽  
Author(s):  
Junyan Ma ◽  
Qian Li ◽  
Haidong Tan ◽  
Hao Jiang ◽  
Kuikui Li ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Specific Activity ◽  
Jerusalem Artichoke ◽  
Fine Tuning ◽  
Substrate Affinity ◽  
Carbohydrate Binding ◽  
Secondary Structure Analysis ◽  
C Terminus ◽  
Glycosylation Sites ◽  
Carbohydrate Binding Modules

Abstract Background Inulinase can hydrolyze polyfructan into high-fructose syrups and fructoligosaccharides, which are widely used in food, the medical industry and the biorefinery of Jerusalem artichoke. In the present study, a recombinant exo-inulinase (rKcINU1), derived from Kluyveromyces cicerisporus CBS4857, was proven as an N-linked glycoprotein, and the removal of N-linked glycan chains led to reduced activity. Results Five N-glycosylation sites with variable high mannose-type oligosaccharides (Man3–9GlcNAc2) were confirmed in the rKcINU1. The structural modeling showed that all five glycosylation sites (Asn-362, Asn-370, Asn-399, Asn-467 and Asn-526) were located at the C-terminus β-sandwich domain, which has been proven to be more conducive to the occurrence of glycosylation modification than the N-terminus domain. Single-site N-glycosylation mutants with Asn substituted by Gln were obtained, and the Mut with all five N-glycosylation sites removed was constructed, which resulted in the loss of all enzyme activity. Interestingly, the N362Q led to an 18% increase in the specific activity against inulin, while a significant decrease in thermostability (2.91 °C decrease in Tm) occurred, and other single mutations resulted in the decrease in the specific activity to various extents, among which N467Q demonstrated the lowest enzyme activity. Conclusion The increased enzyme activity in N362Q, combined with thermostability testing, 3D modeling, kinetics data and secondary structure analysis, implied that the N-linked glycan chains at the Asn-362 position functioned negatively, mainly as a type of steric hindrance toward its adjacent N-glycans to bring rigidity. Meanwhile, the N-glycosylation at the other four sites positively regulated enzyme activity caused by altered substrate affinity by means of fine-tuning the β-sandwich domain configuration. This may have facilitated the capture and transfer of substrates to the enzyme active cavity, in a manner quite similar to that of carbohydrate binding modules (CBMs), i.e. the chains endowed the β-sandwich domain with the functions of CBM. This study discovered a unique C-terminal sequence which is more favorable to glycosylation, thereby casting a novel view for glycoengineering of enzymes from fungi via redesigning the amino acid sequence at the C-terminal domain, so as to optimize the enzymatic properties.

scholarly journals Characterization of two telomeric DNA processing reactions in Saccharomyces cerevisiae.

1988 ◽  
Vol 8 (11) ◽  
pp. 4642-4650 ◽  
Author(s):  
A W Murray ◽  
T E Claus ◽  
J W Szostak
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Division ◽  
Dna Polymerase ◽  
Dna Sequences ◽  
Inverted Repeat ◽  
Telomeric Sequence ◽  
Telomeric Dna ◽  
Telomeric Sequences ◽  
Telomere Elongation

We have investigated two reactions that occur on telomeric sequences introduced into Saccharomyces cerevisiae cells by transformation. The elongation reaction added repeats of the yeast telomeric sequence C1-3A to telomeric sequences at the end of linear DNA molecules. The reaction worked on the Tetrahymena telomeric sequence C4A2 and also on the simple repeat CA. The reaction was orientation specific: it occurred only when the GT-rich strand ran 5' to 3' towards the end of the molecule. Telomere elongation occurred by non-template-directed DNA synthesis rather than any type of recombination with chromosomal telomeres, because C1-3A repeats could be added to unrelated DNA sequences between the CA-rich repeats and the terminus of the transforming DNA. The elongation reaction was very efficient, and we believe that it was responsible for maintaining an average telomere length despite incomplete replication by template-directed DNA polymerase. The resolution reaction processed a head-to-head inverted repeat of telomeric sequences into two new telomeres at a frequency of 10(-2) per cell division.

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