scholarly journals Systemic Control of Cell Division and Endoreduplication by NAA and BAP by Modulating CDKs in Root Tip Cells ofAllium cepa

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Jigna G. Tank ◽  
Vrinda S. Thaker
Keyword(s):  
Cell Division ◽  
Allium Cepa ◽  
Vegetative Growth ◽  
Research Work ◽  
Colchicine Treatment ◽  
Root Tip ◽  
Root Tips ◽  
Ofallium Cepa ◽  
Elongation Process ◽  
Growth Formation

Molecular mechanism regulated by auxin and cytokinin during endoreduplication, cell division, and elongation process is studied by usingAllium cepa rootsas a model system. The activity of CDK genes modulated by auxin and cytokinin during cell division, elongation, and endoreduplication process is explained in this research work. To study the significance of auxin and cytokinin in the management of cell division and endoreduplication process in plant meristematic cells at molecular level endoreduplication was developed in root tips ofAllium cepaby giving colchicine treatment. There were inhibition of vegetative growth, formation of c-tumor at root tip, and development of endoreduplicated cells after colchicine treatment. This c-tumor was further treated with NAA and BAP to reinitiate vegetative growth in roots. BAP gave positive response in reinitiation of vegetative growth of roots from center of c-tumor. However, NAA gave negative response in reinitiation of vegetative growth of roots from c-tumor. Further, CDKs gene expression analysis from normal, endoreduplicated, and phytohormone (NAA or BAP) treated root tip was done and remarkable changes in transcription level of CDK genes in normal, endoreduplicated, and phytohormones treated cells were observed.

scholarly journals Genotoxic Effect of Heavy Metals Cr, Cu, Pb and Zn using Allium cepa L.

2017 ◽  
Vol 14 (3) ◽  
pp. 1181-1186 ◽  
Author(s):  
M.N. Abubacker ◽  
C. Sathya
Keyword(s):  
Heavy Metals ◽  
Allium Cepa ◽  
Chromosomal Abnormalities ◽  
Root Tip ◽  
Chromosome Loss ◽  
Chromosome Break ◽  
Root Tips ◽  
Lead And Zinc ◽  
Chromosome Bridge ◽  
Copper Lead

ABSTRACT: Angiosperms are recognized as appropriate genetic models to detect heavy metal based environmental mutagens and are used in monitoring studies. Allium cepa (onion) has been used to evaluate DNA damages like chromosome aberrations and abnormalities in the mitotic cycle. The aim of the present study is to analyze the cytotoxic effects of chromium, copper, lead and zinc in A. cepa root tip squash mitotic cell divisions. The root tips were treated with three concentrations, viz. 5, 10 and 20 mg/100 ml of chromium, copper, lead and zinc at room temperature for 24 h. Mitotic indices and chromosomal abnormalities were calculated. It was observed that these heavy metals induced different types of chromosomal abnormalities comprising of Chromosome break, Chromosome bridge, C-mitosis, Vagrant, Delayed Anaphase and Vagrant, Chromosome Loss, Polyploidy and Chromosome Bridge, Chromosome Loss and Loculated Nucles, Stickiness, Multipolarity and Polyploid prophase along with the increasing doses. The effect of chromium and lead at 20 mg/100 ml concentration was found to be more toxic rather than copper and zinc to the root meristem of A. cepa. The ranking of cytotoxic potentials was in the descending order: lead > chromium > copper > zinc.

scholarly journals Effect of Ferrous Gluconate on Chromosomal Abnormality Index of Allium Cepa Root Tip

2021 ◽  
Vol 9 (4) ◽  
pp. 755-758
Author(s):  
Nergis Kaya
Keyword(s):  
Allium Cepa ◽  
Chromosomal Aberration ◽  
Chromosomal Abnormality ◽  
Genotoxic Effect ◽  
Root Tip ◽  
Control Group ◽  
Root Tips ◽  
Ferrous Gluconate ◽  
Allium Cepa L ◽  
Abnormality Index

In completed research, ferrous gluconate -a food additive- used to preserve black color to prevent discoloration during storage in ripe black olives, and Allium cepa L. species. A. cepa L. roots were treated with different doses of ferrous gluconate. The effective concentration EC50 (0.068 g/l) was determined. A. cepa root tips were treated with EC50/2 (0.034 g/l), EC50 (0.068 g/l), 2XEC50 (0.136 g/l) dose for 24, 48, 72 hours, and afterward, the root tips were prepared for observation under the light microscope according to the method of preparing mitotic preparation. Chromosomal abnormality index (CAI) and genotoxic effect of ferrous gluconate in A. cepa root tip cells were determined. Repeated measurement ANOVA and TUKEY multiple comparison tests were used to investigate the effect of time and dose together on genotoxicity. C-mitosis, polyploidy, polar shifting in anaphase, polar shifting in telophase, equatorial plate shifting, laggard chromosome was observed by microscope. The highest CAI (70.16±4.85) was observed at 72h for 2XEC50 dose. Chromosomal aberration is also observed in control group. While the most common chromosomal aberration is determined as C-mitosis; The least observed chromosomal aberration is determined as polyploidy. Research results revealed that ferrous gluconate has a genotoxic effect on the root tip of A. cepa.

DIURNAL RHYTHMS IN MITOSIS OF CELLS OF THE ONION ROOT TIP MERISTEM

1971 ◽  
Vol 13 (3) ◽  
pp. 597-599 ◽  
Author(s):  
Richard C. Bishop ◽  
Richard M. Klein
Keyword(s):  
Mitotic Activity ◽  
Allium Cepa ◽  
Constant Temperature ◽  
Time Of Day ◽  
Diurnal Rhythms ◽  
Root Tip ◽  
Root Tips ◽  
Complete Darkness ◽  
Onion Root

Seeds of Allium cepa were grown in complete darkness at constant temperature. The root tips, collected from hours 72 to 96 after the start of imbibition, exhibited four maxima and four minima in mitotic activity. The timing of this rhythm was dependent upon the time of imbibition and not upon the time of day.

scholarly journals Evaluation of Cytotoxic and Genotoxic Effect of Acacia nilotica (L.) Delile Extract Using Allium cepa Bioassay

2020 ◽  
pp. 154-159
Author(s):  
Samah Bodowara ◽  
Fauzia El Garaboli ◽  
Salem El shatshat
Keyword(s):  
Cell Division ◽  
Allium Cepa ◽  
Chromosomal Aberrations ◽  
Genetic Material ◽  
Genotoxic Effect ◽  
Bark Extract ◽  
Root Tips ◽  
Mitotic Abnormalities ◽  
Dividing Cells ◽  
Allium Cepa Assay

The present study aimed to measure the cytotoxic and genotoxic effect of the bark of A. nilotica extract. Allium cepa assay was used to find out the effect of A. nilotica extract on chromosome structure and behavior during cell division. The root tips meristem cells were treated with different concentration of A. nilotica bark aqueous extract (0.1, 0.01 and 0.001mg/ml) for 4, 6, 12 and 24 hours, respectively. Cytological analysis revealed decreasing in cell division in all used concentration especially at high ones. The obtained results indicate that aqueous extracts of A. nilotica plant have the ability to decrease the (MI%) values with increasing the concentration at (P<0.005). All treatments have caused different kind of mitotic abnormalities and chromosomal aberrations, such as: change percentage of mitotic phases, C-mitosis, stickiness, chromosome bridges, Micronucleus and vagrant chromosome. The action of A. nilotica bark extract on the genetic material led to decrease in dividing cells number which was concentration and time depended. This inhibition of cell division was due to disturbances in nucleus as a result of inhibition of DNA synthesis. KEY WORDS: Allium cepa assay: A. nilotica: Chromosomal aberrations; MI.

scholarly journals Antigenotoxic potential of gel extract of Aloe vera against Sodium azide genotoxicity in Allium cepa cells

2021 ◽  
pp. 1-5
Author(s):  
Akeem Akinboro ◽  
Aisha Jimoh
Keyword(s):  
Cell Division ◽  
Allium Cepa ◽  
Sodium Azide ◽  
Dose Range ◽  
Aloe Vera ◽  
Dependent Manner ◽  
Root Tips ◽  
Aloe Vera Gel ◽  
Lower Dose Range ◽  
Dose Dependent

Nowadays, the increasing rate of human exposure to various kinds of environmental mutagens has necessitated the search for natural antimutagens /antigenotoxic agents in natural products. In this study, Aloe vera gel extract was tested for its possible antigenotoxicity following the Allium cepa assay. Ten onions (Allium cepa) per dose were grown for 48 and 72 hours on gel extract of A. vera at 6.25%, 12.5%, 25.0%, 50.0% and 100.0% in combination with sodium azide (0.05mg/ml) solution for microscopic and macroscopic evaluations, respectively. Distilled water and sodium azide were the negative and positive controls, respectively. The cell division in the root tips, and root growth in the exposed A. cepa were inhibited in a dose dependent manner by the mixture of A. vera and sodium azide. However, the mixture of absolute (100.0%) dose and sodium azide completely arrested cell division and induced a lower root length than that recorded for sodium azide alone. The genotoxicity of sodium azide was inversely reduced by the doses of A. vera except at 100.0%. These results show that gel extract of A. vera possesses strong antigenotoxic /antimutagenic potency at lower dose range of 6.25% to 25.0% in A. cepa cells, however, its higher doses above 50.0% to 100.0% could be severely toxic when being considered for suppression of environmental mutagens’ mutagenicity or genotoxicity. This suggests that gel extract of A. vera contains phytochemical(s) that can be useful in the development of anticancer drug.

scholarly journals Asymmetric distribution of cytokinins determines root hydrotropism in Arabidopsis thaliana

Cell Research ◽  
2019 ◽  
Vol 29 (12) ◽  
pp. 984-993 ◽  
Author(s):  
Jinke Chang ◽  
Xiaopeng Li ◽  
Weihao Fu ◽  
Jiawen Wang ◽  
Yueyuan Yong ◽  
...  
Keyword(s):  
Cell Division ◽  
Water Potential ◽  
Molecular Mechanisms ◽  
Plant Root ◽  
Moisture Gradient ◽  
Root Tip ◽  
Asymmetric Distribution ◽  
Root Tips ◽  
Cytokinin Biosynthesis ◽  
Primary Determinant

Abstract The phenomenon of plant root tips sensing moisture gradient in soil and growing towards higher water potential is designated as root hydrotropism, which is critical for plants to survive when water is a limited factor. Molecular mechanisms regulating such a fundamental process, however, are largely unknown. Here we report our identification that cytokinins are key signaling molecules directing root growth orientation in a hydrostimulation (moisture gradient) condition. Lower water potential side of the root tip shows more cytokinin response relative to the higher water potential side. Consequently, two cytokinin downstream type-A response regulators, ARR16 and ARR17, were found to be up-regulated at the lower water potential side, causing increased cell division in the meristem zone, which allows the root to bend towards higher water potential side. Genetic analyses indicated that various cytokinin biosynthesis and signaling mutants, including the arr16 arr17 double mutant, are significantly less responsive to hydrostimulation. Consistently, treatments with chemical inhibitors interfering with either cytokinin biosynthesis or cell division completely abolished root hydrotropic response. Asymmetrically induced expression of ARR16 or ARR17 effectively led to root bending in both wild-type and miz1, a previously known hydrotropism-defective mutant. These data demonstrate that asymmetric cytokinin distribution is a primary determinant governing root hydrotropism.

scholarly journals Actin in the preprophase band of Allium cepa.

1987 ◽  
Vol 104 (6) ◽  
pp. 1515-1519 ◽  
Author(s):  
B A Palevitz
Keyword(s):  
Thin Layer ◽  
Allium Cepa ◽  
Colchicine Treatment ◽  
Preprophase Band ◽  
Fluorescence Microscope ◽  
Root Tips ◽  
Rhodamine Phalloidin ◽  
Interphase Cells ◽  
Triton X

F-actin has been identified in the preprophase band of Allium cepa. Cells attached to subbed slides were obtained from formaldehyde-fixed root tips digested in EGTA and Cellulysin. The air-dried cells were extracted in Triton X-100, treated with rhodamine-phalloidin, rinsed briefly in PBS, and viewed in the fluorescence microscope. Interphase cells contain a network of actin fibers that extends into all areas of the cytoplasm. During preprophase, the network is replaced by a band of fibers aligned in the position of the preprophase band. Colocalization of F-actin with rhodamine-phalloidin and microtubules with tubulin immunocytochemistry confirms that the two bands are coincident. The actin appears to comprise a thin layer of fibers next to the plasmalemma. Like the microtubule preprophase band, the actin band narrows as preprophase progresses and disappears by midprophase. Fluorescent actin bands are not seen in fixed cells pretreated with excess unlabeled phalloidin before staining. They are also absent in roots exposed to cytochalasins B and D before fixation, but preprophase band microtubules at all stages of aggregation are still present. Colchicine treatment leads to the loss of both preprophase band microtubules and actin. The possible function of preprophase band actin is discussed.

scholarly journals Environmental Risk Characterization of an Antiretroviral (ARV) Lamivudine in Ecosystems

2021 ◽  
Vol 18 (16) ◽  
pp. 8358
Author(s):  
Elizabeth Oyinkansola Omotola ◽  
Bettina Genthe ◽  
Luyanda Ndlela ◽  
Olatunde Stephen Olatunji
Keyword(s):  
Daphnia Magna ◽  
Allium Cepa ◽  
Lactuca Sativa ◽  
Germination Rate ◽  
Survival Rates ◽  
Antiretroviral Drugs ◽  
Trophic Levels ◽  
Adverse Impact ◽  
Root Tip ◽  
Root Tips

Antiretroviral drugs for the treatment of human immunodeficiency virus (HIV) and other viral infections are among the emerging contaminants considered for ecological risk assessment. These compounds have been reported to be widely distributed in water bodies and other aquatic environments, while data concerning the risk they may pose to unintended non-target species in a different ecosystem (environment) is scanty. In South Africa and other developing countries, lamivudine is one of the common antiretrovirals applied. Despite this, little is known about its environmental impacts as an emerging contaminant. The present study employed a battery of ecotoxicity bioassays to assess the environmental threat lamivudine poses to aquatic fauna and flora. Daphnia magna (filter feeders), the Ames bacterial mutagenicity test, Lactuca sativa (lettuce) germination test, and the Allium cepa root tip assay were conducted, testing lamivudine at two concentrations (10 and 100 µg/L), with environmental relevance. The Daphnia magna toxicity test revealed a statistically significant response (p << 0.05) with a mortality rate of 85% on exposure to 100 µg/L lamivudine in freshwater, which increased to 100% at 48-h exposure. At lower concentrations of 10 µg/L lamivudine, 90% and 55% survival rates were observed at 24 h and 48 h, respectively. No potential mutagenic effects were observed from the Ames test at both concentrations of lamivudine. Allium cepa bioassays revealed a noticeable adverse impact on the root lengths on exposure to 100 µg/L lamivudine. This impact was further investigated through microscopic examination, revealing some chromosomal aberration in the exposed Allium cepa root tips. The Lactuca sativa bioassay showed a slight adverse impact on both the germination rate of the seeds and their respective hypocotyl lengths compared to the control. Overall, this indicates that lamivudine poses an ecological health risk at different trophic levels, to both flora and fauna, at concentrations previously found in the environment.

scholarly journals Effects of cadmium on root growth, cell division and micronuclei formation in root tip cells of Allium cepa var. agrogarum L.

Phyton ◽  
2014 ◽  
Vol 83 (1) ◽  
pp. 291-298
Author(s):  
Wang QL ◽  
LT Zhang ◽  
JH Zou ◽  
DH Liu ◽  
JY Yue
Keyword(s):  
Cell Division ◽  
Root Growth ◽  
Allium Cepa ◽  
Root Tip ◽  
Tip Cells ◽  
Root Tip Cells

Effect of DCPA on Anatomy and Cytology of Roots

Weed Science ◽  
1968 ◽  
Vol 16 (4) ◽  
pp. 449-452 ◽  
Author(s):  
S. W. Bingham
Keyword(s):  
Cell Division ◽  
Cell Size ◽  
Allium Cepa ◽  
Cynodon Dactylon ◽  
Soil Surface ◽  
Cell Enlargement ◽  
Root Tips ◽  
Histological Studies ◽  
Metaphase Stage ◽  
Zea May

Dimethyl 2,3,5,6-tetrachloroterephthalate (DCPA) on the soil surface inhibited rooting at bermudagrass (Cynodon dactylon L., var 328) stolon nodes. Histological studies of these root tips showed that cell division had ceased while cell enlargement continued for some time. Cells became excessively large and irregularly shaped. In corn (Zea may L., var. Pioneer 310), radicle cell size was about the same in both instances; however, treated tissue contained six times as many dinucleate cells as untreated radicle tissue. Numerous nuclei were at metaphase stage of mitosis in treated tissue. In untreated onion (Allium cepa L., var. Yellow Globe Danvers) root tips, many nuclei were found at anaphase and telophase stage of mitosis while very few cells were dividing in treated tissue.

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