scholarly journals Incorporation of thymidine into onion root meristematic cell nuclei in presence of hydroxyurea and its role in recovery of mitotic activity

2015 ◽  
Vol 46 (4) ◽  
pp. 701-711
Author(s):  
H. Habdas
Keyword(s):  
S Phase ◽  
The Other ◽  
Cell Nuclei ◽  
Onion Root ◽  
Meristematic Cells ◽  
Hydroxyurea Treatment ◽  
Mitotic Block ◽  
Root Meristematic Cells ◽  
Mitotic Figures ◽  
Root Meristematic Cell

Hydroxyurea treatment of onion roots induced mitotic block which was released by transfer of bulbs to water, and also to some extent by addition of cold or <sup>3</sup>H-thymidine to hydroxyurea solutions. In presence of hydroxyurea there was noted very intense incorporation of <sup>3</sup>H-thymidine into cell nuclei, giving labelling index of 40-70%. However, all the mitotic figures appearing in presence of hydroxyurea and <sup>3</sup>H-thymidine were unlabelled. On the other hand, labelled mitotic figures were obtained when roots incubated with <sup>3</sup>H-thymidine in presence of hydroxyurea had been transferred to water. Incorporation of <sup>3</sup>H-uridine was unaffected by hydroxyurea. The results show that hydroxyurea arrests onion root meristematic cells, either in the S phase and the G<sub>2</sub> phase. Enhanced incorporation of <sup>3</sup>H-thymidine in the presence of hydroxyurea, and release by added thymidine of the mitotic block indicate that hydroxyurea induces in onion root meristematic cells a particular shortage of thymidylate.

Changes of dictyosome ultrastructure during the cell cycle in onion root meristematic cells. A morphometric and stereological study

PROTOPLASMA ◽  
1988 ◽  
Vol 146 (1) ◽  
pp. 35-40 ◽  
Author(s):  
J. A. Gonzalez-Reyes ◽  
F. Grac�a-Navarro ◽  
G. Garcia-Herdugo ◽  
P. Navas
Keyword(s):  
Cell Cycle ◽  
Onion Root ◽  
Meristematic Cells ◽  
Root Meristematic Cells

Ultrastructural association of the chromatin-containing lacunar spaces with the vacuolar component of the interphase nucleolus in Allium cepa

1982 ◽  
Vol 60 (12) ◽  
pp. 2624-2628 ◽  
Author(s):  
L. A. Chouinard
Keyword(s):  
Granular Material ◽  
Allium Cepa ◽  
Ultrastructural Level ◽  
Observational Evidence ◽  
The Other ◽  
Active Chromatin ◽  
Meristematic Cells ◽  
Fibrillar Material ◽  
Nucleolar Organizing Region ◽  
Root Meristematic Cells

At the ultrastructural level, some of the chromatin-containing lacunar spaces of the interphase nucleolus in root meristematic cells of Allium cepa are seen to be walled off, on one side, by dense-fibrillar material and to be contiguous, on the other side, to electron-transparent areas, of variable sizes and shapes, bordered by dense-granular material continuous with and indistinguishable from the dense-granular component of the nucleolar mass. These electron-transparent areas associated with the lacunar spaces are equated with nucleolar vacuoles since they contain scattered preribosomal-like granules and fibrils and are rimmed by dense-granular material. The relevant observational evidence would be consistent with the view that loops of transcriptionnally active chromatin emanating from the nucleolar organizing region project radially into either only the dense-fibrillar or both the dense-fibrillar and the interior of the electron-transparent vacuolar areas seen to be contiguous to the lacunar spaces in question. In relation to this problem, it is of interest to note that the vacuolar spaces of the interphase nucleolus in Allium cepa occasionally display within their confines discrete masses of fibrillar material, possibly chromatinic in character, and in various states of condensation and configuration.

scholarly journals The yeast S phase checkpoint enables replicating chromosomes to bi-orient and restrain spindle extension during S phase distress

2005 ◽  
Vol 168 (7) ◽  
pp. 999-1012 ◽  
Author(s):  
Jeff Bachant ◽  
Shannon R. Jessen ◽  
Sarah E. Kavanaugh ◽  
Candida S. Fielding
Keyword(s):  
Dna Replication ◽  
Chromosome Segregation ◽  
Replication Fork ◽  
S Phase ◽  
Origin Of Replication ◽  
Independent Manner ◽  
Checkpoint Signaling ◽  
Hydroxyurea Treatment ◽  
Chromatid Cohesion ◽  
S Phase Checkpoint

The budding yeast S phase checkpoint responds to hydroxyurea-induced nucleotide depletion by preventing replication fork collapse and the segregation of unreplicated chromosomes. Although the block to chromosome segregation has been thought to occur by inhibiting anaphase, we show checkpoint-defective rad53 mutants undergo cycles of spindle extension and collapse after hydroxyurea treatment that are distinct from anaphase cells. Furthermore, chromatid cohesion, whose dissolution triggers anaphase, is dispensable for S phase checkpoint arrest. Kinetochore–spindle attachments are required to prevent spindle extension during replication blocks, and chromosomes with two centromeres or an origin of replication juxtaposed to a centromere rescue the rad53 checkpoint defect. These observations suggest that checkpoint signaling is required to generate an inward force involved in maintaining preanaphase spindle integrity during DNA replication distress. We propose that by promoting replication fork integrity under these conditions Rad53 ensures centromere duplication. Replicating chromosomes can then bi-orient in a cohesin-independent manner to restrain untimely spindle extension.

Effects of caffeine treatment on aged porcine oocytes: parthenogenetic activation ability, chromosome condensation and development to the blastocyst stage after somatic cell nuclear transfer

Zygote ◽  
2005 ◽  
Vol 13 (4) ◽  
pp. 335-345 ◽  
Author(s):  
Masaki Iwamoto ◽  
Akira Onishi ◽  
Dai-ichiro Fuchimoto ◽  
Tamas Somfai ◽  
Shun-ichi Suzuki ◽  
...  
Keyword(s):  
Somatic Cell ◽  
Blastocyst Stage ◽  
The Other ◽  
Control Group ◽  
Blastocyst Formation ◽  
Cell Nuclei ◽  
Somatic Nucleus ◽  
Membrane Breakdown ◽  
Caffeine Treatment ◽  
M Phase

The possibility of using aged porcine oocytes treated with caffeine, which inhibits the decrease in M-phase promoting factor activity, for pig cloning was evaluated. Cumulus–oocyte complexes (COCs) were cultured initially for 36h and subsequently with or without 5mM caffeine for 24h (in total for 60h: 60CA+ or 60CA– group, respectively). As a control group, COCs were cultured for 48h without caffeine (48CA–). The pronuclear formation rates at 10h after electrical stimulation in the 60CA+ and 60CA– groups decreased significantly (p<0.05) compared with the 48CA– group. However, the fragmentation rate was significantly higher (p<0.05) in the 60CA– group than in the 60CA+ and 48CA– groups. When the stimulated oocytes were cultured for 6 days, the 60CA+ group showed significantly lower blastocyst formation and higher fragmentation or degeneration rates (p<0.05) than the 48CA– group. However, the number of total cells in blastocysts was not affected by maturation period or caffeine treatment. When somatic cell nuclei were injected into the non-enucleated oocytes and exposed to cytoplasm for a certain duration (1–11h) before the completion of maturation (48 or 60h), the rate of nuclear membrane breakdown after exposure to cytoplasm for 1–2h in the 60CA– oocytes was significantly lower (p;<0.05) than in the other experimental groups. The rate of scattered chromosome formation in the same 60CA– group tended to be lower (p=0.08) than in the other groups. After the enucleation and transfer of nuclei, blastocyst formation rates in the 60CA+ and 60CA– groups were significantly lower (p<0.05) than in the 48CA– group. Blastocyst quality did not differ among all the groups. These results suggest that chromosome decondensation of the transplanted somatic nucleus is affected by both the duration of exposure to cytoplasm and the age of the recipient porcine oocytes, and that caffeine treatment promotes nuclear remodelling but does not prevent the decrease in the developmental ability of cloned embryos caused by oocyte aging.

scholarly journals Action of Ponceau 4R (E-124) food dye on root meristematic cells of Allium cepa L.

2015 ◽  
Vol 37 (1) ◽  
pp. 101 ◽  
Author(s):  
Gleuvânia Santana Marques ◽  
Josefa Janaína do Anjos Sousa ◽  
Ana Paula Peron
Keyword(s):  
Allium Cepa ◽  
Meristematic Cells ◽  
Food Dye ◽  
Root Meristematic Cells ◽  
Ponceau 4R

scholarly journals Rooting Induction in Allium cepa for the Study of Mitosis in a Hydroponics System

2020 ◽  
pp. 1-5
Author(s):  
Geovanio Alves da Silva ◽  
Eder Ferreira Arriel ◽  
Mellina Nicácio da Luz ◽  
Valeska Regina Silva Martins ◽  
Elisabeth de Oliveira ◽  
...  
Keyword(s):  
Allium Cepa ◽  
Genetic Information ◽  
Water Source ◽  
The Other ◽  
Root Mass ◽  
Root Number ◽  
Experiment Data ◽  
Hydroponic System ◽  
Meristematic Cells ◽  
System Water

The study of cell division processes is important for the understanding of how genetic information is transmitted from cell to cell and to descendants. To observe the phases of mitosis in meristematic cells of the onion root (Allium cepa), it is necessary to induce the rooting of this bulb that can be influenced by some factors like the type of water and the preparation form of the bulb of the onion for the success of rhizogenesis. In view of the above, the objective was to evaluate the influence of the water source and the opening of holes in the stem of the propagule to induce rooting in a hydroponic system. Two experiments were installed. In the first, one of the treatments was used distilled water and treated water. In the other experiment, three treatments were evaluated (without holes, few holes and a lot of holes in the stem of the bulb). Five days after installation of the first experiment, data were collected on the number of bulbs that gave off roots and this variable was analyzed using the X2 test. In the other test, also at five days, root number and fresh root mass data were obtained and the data were submitted for analysis of variance and the means were compared by the Scott-Knott test. For the induction of rooting in onion bulbs (Allium cepa) in a hydroponic system, water should be used, preferably treated, cleaned and decontaminated. The stem of the onion bulb should receive many perforations to facilitate the absorption of water with the essential nutrients for rooting.

scholarly journals Influence of extract from shoots of Taxus baccata var. elegantissima on ultrastructure and tubulin cytoskeleton of meristematic cells of Allium cepa L. roots

2014 ◽  
Vol 71 (3) ◽  
pp. 211-221 ◽  
Author(s):  
Agnieszka Majewska ◽  
Mirosława Furmanowa ◽  
Kazimierz Głowniak ◽  
Joanna Guzewska ◽  
Alicja Zobel ◽  
...  
Keyword(s):  
Allium Cepa ◽  
Chromatin Condensation ◽  
Preprophase Band ◽  
Taxus Baccata ◽  
Cell Nuclei ◽  
Root Tips ◽  
Meristematic Cells ◽  
Allium Cepa L ◽  
Interphase Cells ◽  
Average Size

We investigated the influence of extract from <em>Taxus baccata</em> var. Elegantissima (TbE) shoots in 1:8 dilution, containing paclitaxel in concentration of 81,6 µg/g fresh mass on ultrastructure and tubulin cytoskeleton of meristematic cells of <em>Allium cepa</em> L. root tips. Incubation time 3, 6, 12 and 24 h was followed with postincubation in water for 12 and 24 h. During shorter incubation (till 12 h) the surface of the cell nuclei decreased and chromatin became condensed (in comparison to control) but after 24 h the average surface increased and chromatin condensation decreased. In the course of incubation the average size of plastids and vacuoles increased. Moreover, after treatment mitochondria and plastids showed degradation of ultrastructure, which was reversed after 12 h of postincubation. Immunocytochemical assays demonstrated that in the course of incubation in the ThE extract, the tubulin cytoskeleton became partially disorganised. In most interphase cells, cortical microtubules (MTs) lost their oval transverse orientation. The preprophase band (PPB) position in the cell was often asymmetrical. The MTs array of the karyokinetic spindle and phragmoplast was also disturbed. These alterations were completely reversed during postincubation.

scholarly journals Sodium cacodylate as antimitotic agent

2014 ◽  
Vol 57 (3) ◽  
pp. 329-340
Author(s):  
Jadwiga A. Tarkowska
Keyword(s):  
Allium Cepa ◽  
Mitotic Spindle ◽  
Sodium Cacodylate ◽  
Antimitotic Agent ◽  
Ultrastructural Studies ◽  
Meristematic Cells ◽  
Cacodylate Buffer ◽  
Root Meristematic Cells ◽  
Dividing Cells

The effect of pure sodium cacodylate on dividing cells was studied. The root meristematic cells of <em>Allium cepa</em> L. (the roots were squashed in acetoorcein) and endosperm cells of <em>Haemanthus katherinae</em> Bak. (<em>in vitro</em> observations) were used. Serious disturbances in karyokinesis and cytokinesis were found that led most often to the formation of polyploid or multinucleate (<em>A. cepa</em>) cells. These results point to damage of the mitotic spindle and phragmoplast. Careful use of cacodylate buffer in ultrastructural studies of microtubules is advised.

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