scholarly journals Effects of gibberellic acid and AMO-1618 on the development of vegetative systems in generatively matured thalli of Chara vulgaris L.

2014 ◽  
Vol 49 (4) ◽  
pp. 445-458 ◽  
Author(s):  
Maria Kwiatkowska ◽  
Mirosław Godlewski
Keyword(s):  
Gibberellic Acid ◽  
Mitotic Activity ◽  
Main Axis ◽  
Chara Vulgaris ◽  
Cell Divisions ◽  
Lateral Buds ◽  
Apical Cells ◽  
Axenic Conditions ◽  
High Level ◽  
Amo 1618

Effects of GA<sub>3</sub> (10<sup>-11</sup>-10<sup>-4</sup> M) and AMO-1618 (10<sup>-6</sup>-10<sup>-4</sup> M) on the development of generatively matured thalli of <em>Chara vulgaris</em> were investigated during 21-day culture of plants in axenic conditions. It has been found that in the main bud the divisions of apical cells of the thalli are not stimulated by GA<sub>3</sub>, whereas in the lateral buds the cell divisions are stimulated by higher GA<sub>3</sub> concentrations. Subsequent mitotic activity of the apical cells in the branches of the main axis is not stimulated by GA<sub>3</sub>, whereas the lateral buds of these branches are activated. The development of rhizoids in younger nodes is accelerated by high GA<sub>3</sub> concentrations. The elongation of the polynuclear, internodal cells of the main axis and that of pleuridia are inhibited proportionally to the GA<sub>3</sub> concentration. AMO-1618 stimulates the development of new nodes, elongation of internodes and delays the activation of lateral buds as well as the formation of rhizoids. These results suggest that the GA<sub>3</sub>-induced inhibition of elongation of the thalli and diminution of the apical domination is connected with a high level of endogenous gibberellins in the generatively matured thallus.

scholarly journals Changes in the number and size of nucleoli of Chara vulgaris L. antheridial filament cells during the period preceding light-induced re-initiation of cell divisions following a mitodepressive effect of darkness

2014 ◽  
Vol 68 (4) ◽  
pp. 251-254
Author(s):  
Maria Kwiatkowska ◽  
Ewa Papiernik
Keyword(s):  
Cell Cycle ◽  
Developmental Stage ◽  
Mitotic Activity ◽  
Silver Staining ◽  
Staining Method ◽  
Chara Vulgaris ◽  
Cell Divisions ◽  
A Cell ◽  
Silver Staining Method

The changes in number and size of nucleoli of <em>Chara vulgaris</em> antheridial filament cells were monitored with the use of Howell and Black's silver staining method. After a 3-day mitodepressive treatment with darkness the cells were exposed to light which reactivated mitotic activity after 18-20 hours. Eight-celled antheridial filaments were observed. In the period preceding light-induced re-initiation of mitoses a gradual reconstruction of the number and size of nucleoli characteristic of control, as well as their total area per nucleus appeared. The obtained results indicate that one of the important conditions for a cell to be able to divide is accumulation of nucleolus components characteristic of a given developmental stage and this controls nucleologenesis of the subsequent cell cycle.

scholarly journals Effect of gibberellic acid on the formation and development of antheridia and oogonia in Chara vulgaris L.

2014 ◽  
Vol 49 (4) ◽  
pp. 459-469 ◽  
Author(s):  
Mirosław Godlewski ◽  
Maria Kwiatkowska
Keyword(s):  
Gibberellic Acid ◽  
The Other ◽  
Control Material ◽  
Chara Vulgaris ◽  
Other Hand ◽  
Axenic Conditions

The experiments were performed on <em>Chara vulgaris</em> thalli cultivated in axenic conditions. It has been found that application of GA<sub>3</sub> at concentrations of 10<sup>-9</sup> -10<sup>-4</sup> M has no effect on the numbers of developing antheridia and oogonia. GA<sub>3</sub> stimulates the gemmation of capitular cells thus increasing the number of filaments in antheridia (by 45% when 10<sup>-8</sup> M is used). The number of mitotic cycles preceding the differentiation of spermatozoids is not significantly modified by this gibberellin. The number of spermatozoids in antheridia increases by about 20% when 10<sup>-8</sup> -10<sup>-6</sup> M GA<sub>3</sub> concentrations are used. GA<sub>3</sub> shortens the duration of spermatogenesis (by 2.5 days, at 10<sup>-7</sup> M concentration). This effect is due to a shortening of the mitotic cycles in filaments. On the other hand, the time of spermatozoid differentiation, which in the control material lasts about 5.3 days, is not changed significantly by GA<sub>3</sub>. GA<sub>3</sub> hastens the maturation of oogonia and the formation of oospores - both effects are proportional to the GA<sub>3</sub> concentration used.

scholarly journals Effect of GA3, IAA and their mixtures on the formation and development of cell systems in the vegetative and generative thallus of Chara vulgaris L.

2014 ◽  
Vol 60 (3-4) ◽  
pp. 313-326 ◽  
Author(s):  
Maria Kwiatkowska ◽  
Aleksandra Gosek ◽  
Mirosław Godlewski
Keyword(s):  
Inhibitory Effect ◽  
Main Axis ◽  
Stimulatory Action ◽  
Cell Systems ◽  
Low Concentration ◽  
Chara Vulgaris ◽  
Vegetative Part ◽  
Lateral Branches ◽  
High Level ◽  
Generative Organs

In concentrations ranging from 10<sup>-7</sup> to 10<sup>-5</sup> M IAA strongly stimulates the growth of the main axis and pleuridia internodal cells, while it does not affect the number of lateral branches and generative organs. In the higher concentrations it reduces the number of spermatozoids in the antheridium. In the same concentration range, GA<sub>3</sub>, inhibits the growth of the main axis and pleuridia internodal cells, does not affect the number of lateral branches, increases the number of antheridia and increases the number of forming spermatozoids. Incubation in mixture of both regulators has shown that: a) IAA eliminates the inhibitory effect of GA<sub>3</sub> on the growth of internodal cells of the main axis and its stimulatory action is slightly weakened by GA<sub>3</sub>, b) IAA in a concentration of 10<sup>-5</sup> M along with a low concentration of GA<sub>3</sub>, (10<sup>-7</sup>) increases the number of main axis lateral branches. The conclusion is drawn that the growth of the vegetative part of the thallus is more intense when auxin predominates, but generative development requires a high level of gibberellin.

scholarly journals The effects of pulse cycloheximide treatments on the light-induced recovery of mitotic divisions in antheridial filaments of Chara vulgaris

2014 ◽  
Vol 68 (1) ◽  
pp. 9-14
Author(s):  
Maria Kwiatkowska ◽  
Sławomir Malinowski ◽  
Janusz Maszewski
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Mitotic Activity ◽  
Total Darkness ◽  
Chara Vulgaris ◽  
Cell Divisions ◽  
Cycle Arrest ◽  
Starting Point ◽  
G2 Phase ◽  
Preliminary Study

Within the proliferative period of spermatogenesis in <em>Chara vulgaris</em>, the progression throughout successive cell divisions in antheridial filaments is greatly influenced by changes in photoperiodic conditions. The extended (4-day) period of total darkness brings about cell cycle arrest in the early G2 phase. The recovery of mitosis requires about 20 hours of exposition to light. In the present study, a series of 8 pulse incubations of plants in cycloheximide (Cx; 2.5 mg/I, 2.5 h each pulse) were performed within the period elapsing till the resumption of mitotic divisions. Depending on the time of treatment, the effects induced by Cx vary considerably. Within the first 10 hs of exposition to light, incubations with Cx result in the delays of mitoses; within the period between the 10th and the 17th h, mitotic divisions become blocked, and, following the 17.5 h of light-induced recovery, no influence of Cx is noticed on mitotic activity, as compared with the untreaed control plants. The obtained results provide a starting point for the characteristic of proteins synthesized during the G2 phase and a preliminary study on those mechanisms, which become engaged in the regulation of the G1-deficient cell cycle evidenced in antheridial filaments of <em>Chara</em>.

scholarly journals The effect of light factor on the development of thallus and generative organs in Chara vulgaris L.

2014 ◽  
Vol 49 (4) ◽  
pp. 397-407 ◽  
Author(s):  
Janusz Maszewski
Keyword(s):  
Mitotic Activity ◽  
Axenic Culture ◽  
Light Period ◽  
Continuous Illumination ◽  
Chara Vulgaris ◽  
The Moment ◽  
Almost All ◽  
Effect Of Light ◽  
Generative Organs

During long-term axenic culture of Chara continuous illumination (L=24) increases mitotic activity of almost all types of cells. In such conditions only initiation of oogonia is inhibited, leading into a strong predomination of male generative organs. Prolonged darkness (L:D=1:23) exerts a mitodepressing effect. Oogonia and antheridia are especially susceptible to the reduction of the light period. Modifications of the elongating growth in various photoperiods are different in the polyploid regions of the vegetative thallus and in haploid cells of the antheridial filaments. Segments of both axial internodes and lateral pleuridia increase their dimensions at L:D=1:23, whereas at L=24 their growth is significantly inhibited. Different reaction is noted in the cells of antheridial filaments: at L=24 they are about 10% longer than in the control (L:D=14:10). The duration of the antheridium aevelopment, from the stage of unicellular filaments to the moment of antheridium opening, is 1.5 days shorter at L=24 as compared with the control. This shortening includes proportionally both the period of divisions within antheridial filaments and the period of spermatozoid differentiation.

Lateral bud growth on excised stem segments: effect of the stem

1975 ◽  
Vol 53 (3) ◽  
pp. 243-248 ◽  
Author(s):  
Carol A. Peterson ◽  
R. A. Fletcher
Keyword(s):  
Sucrose Solution ◽  
Apical Part ◽  
Endogenous Auxin ◽  
Cell Divisions ◽  
Cotyledonary Nodes ◽  
Lateral Buds ◽  
Lateral Bud ◽  
Bud Growth ◽  
Soybean Plants ◽  
Stem Segments

Lateral buds at the cotyledonary nodes of soybean plants grown under the conditions used in this study usually remain inhibited. These buds grow when the apical part of the plant is removed. They will grow, but less strongly, when the roots as well as the apex of the plant are removed and the basal end of the cut stem is placed in a mineral salt solution. Bud growth is further diminished by decreasing the length of stem left attached to the bud. The cotyledon is essential for bud growth on plant segments maintained in nutrient solution, but it can be replaced by a 1% sucrose solution during the early days of bud growth. Buds which are completely detached from the stem and placed in 1% sucrose do not elongate, but a small number of cell divisions are detectable, indicating that the early events of the release from inhibition have occurred. Buds elongate when they are apically or centrally located on stem segments. Increasing the length of the attached stem segments increases the growth of the buds. Additions of the cytokinin benzyladenine to plants causes a dramatic increase in bud growth when buds are attached to stem segments but does not stimulate growth of buds without stem segments. It is concluded that benzyladenine alone will not substitute for a factor(s) present in the stem which is necessary for bud growth. Increasing stem lengths above buds located at the basal ends of segments inhibits bud growth. It is suggested that this may be due to an accumulation of endogenous auxin at the site of the buds.

scholarly journals The effects of experimentally induced rest and exercise on the epidermal mitotic activity of the adult male mouse, Mus musculus L

1948 ◽  
Vol 135 (879) ◽  
pp. 233-242 ◽  
Keyword(s):  
Mitotic Activity ◽  
Adult Male ◽  
Male Mouse ◽  
Time Of Day ◽  
Excessive Exercise ◽  
Adult Male Mouse ◽  
Preliminary Study ◽  
High Level ◽  
Mitosis Rate ◽  
Rest And Exercise

As a preliminary study of the conditions which affect the hour to hour variations in epidermal mitotic activity in the adult male mouse, experiments were carried out involving artificially induced sleep and exercise. In the first experiment the animals were injected with a dose of barbiturates sufficient to induce sleep for a period of 3 or 4 hr. at a time of day when they were usually active. The injections were given at 17.00 hr. as the animals were waking from their afternoon sleep, and they resulted in a sharp rise in mitotic activity. A maximum was reached at 20.00 hr., the time when the mitotic activity of the controls had dropped to a minimum. As the animals recovered and became active, their mitosis rate fell quickly to a low level. In the second experiment the animals were placed in a slowly revolving box, and so forced to remain awake and active throughout an afternoon when they would otherwise have been asleep. This treatment resulted in extremely low mitotic activity, in contrast to which that of the normally sleeping controls rose to a high level. It is probably significant that when the mice were released from the revolving box, and could at last sleep, their mitosis rate remained low. This suggests that the excessive exercise had either resulted in the production of some mitosis-depressing substance which remained in the system, or that some substance vital to mitosis had been used up and took some time to be replaced. The conclusion is now justified that the rate of epidermal mitosis normally increases during sleep, and decreases during hours of wakefulness and exercise. In this way the form of the diurnal mitosis cycle is determined by the habits of the animals.

scholarly journals Influence of hydroxyurea on cell divisions and microtubular cytoskeleton in Allium cepa root meristem

2014 ◽  
Vol 65 (1-2) ◽  
pp. 179-185 ◽  
Author(s):  
H. Q. Zhang ◽  
Y. Q. Li ◽  
M. Kuraś ◽  
J. Bednara ◽  
M. Cresti
Keyword(s):  
Mitotic Activity ◽  
Apical Meristem ◽  
Root Meristem ◽  
Distal Region ◽  
Mitotic Spindles ◽  
Immunofluorescence Method ◽  
Cell Divisions ◽  
Microtubular Cytoskeleton ◽  
Tubulin Immunofluorescence ◽  
Short Time

In onion roots, hydroxyurea (HU) causes a gradual depression of mitotic activity which ceases after 24-36 hrs. The effect is reversible; divisions begin after several hours of recovery and after 12-14 hrs about 90% cells undergo mitosis. Mitotic activity commences in the distal region of the apical meristem, and as a wave it spreads towards the apex. In the roots treated with HU for a short time, the tubulin immunofluorescence method reveals normal arrays of microtubules (MTs). After 36 hrs of HU treatment there are only cortical and endocytoplasmatic MTs. In the recovering roots, preprophase bands (PB) mitotic spindles and phragmoplasts appear. Some PBs are split into two parallel rings. These abnormal PBs mostly occur in elongated cells. Apart from this, HU does not appear to have any significant influence on microtubular organization.

Influence de la photopériode sur le comportement du méristème caulinaire du Celosia cristata

1977 ◽  
Vol 55 (11) ◽  
pp. 1488-1500
Author(s):  
D. Driss-Ecole
Keyword(s):  
Mitotic Activity ◽  
Shoot Apex ◽  
Unstable State ◽  
Axial Zone ◽  
Histological Studies ◽  
Daily Show ◽  
Differentiated Cells ◽  
Long Day ◽  
Celosia Cristata ◽  
High Level

Three groups of plants of Celosia cristata were grown in a 8-h, 12-h, or 16-h day. Histological studies of the shoot apex were performed during the vegetative and the prefloral phases.The apical meristems of the plants subjected to long-day conditions (16 h) flatten (fasciation). At the beginning of the fasciation, an activation of the corpus and a restructuration of the meristem are observed. The transformed meristem shows four superficial layers which cover a group of differentiated cells. The zonation is always recognizable and the apex initiates numerous leaves. The broadening of the meristem is due to the high level of mitotic activity of two opposite regions in the ‘anneau initial’ which takes an elliptical shape and to the peculiar orientation of the mitoses. During this transformation the volumes of the lateral and medullary zones increase while the volume of the axial zone remains almost identical. The long vegetative phase ceases with the homogeneization of the meristematic state of the four superficial layers and with the edification of a prefloral crest.The apex of plants grown under an 8-h photoperiod remains small sized. They never undergo fasciation and reach the prefloral phase very quickly.The meristems of the plants cultivated under 12 h of light daily show an unstable state and sometimes evolve tardily towards fasciation.

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