A.A. El-Ghamery’s research while affiliated with Al-Azhar University and other places

The effect of different benzyladenine (BA) treatments which is a phyto-regulator or plant hormone on the cytology and growth of Nigella sativa L. (Black seed) and Allium cepa L. (onion) were investigated. Six concentrations of benzyladenine ranging from 5 to 55 ppm were applied for 6, 12, 18, 24, 36 and 48 h. The treatments elevate the germination percentages of Nigella sativa L. and Allium cepa L. and increase the root growth of both plants. In contrast concentrations higher than 60 ppm for 48 h were caused an inhibition effect for both plant. The root growth initiation was concentration and/or time dependent. The applied concentrations of BA showed a promotor effect on cell division in root tips of both plants and caused an increase in their mitotic index values (MI). The elevation in MI values in root tips of Nigella sativa L. was more evident than that of Allium cepa L. All treatments changed the frequency of mitotic phases as compared with the control values. All the applied concentrations of BA significantly induced a number of chromosomal aberrations in root tip cells of Nigella sativa L. and Allium cepa L. The total percentages of abnormalities in Nigella sativa L. root tip cells were more than that in Allium cepa L. with all concentrations of BA. The most dominant types of observed abnormalities were stickiness, bridges, and C-mitosis. BA treatments produced a number of mitotic abnormalities in dividing cells in root tips of both plants resulting from its action on the spindle apparatus such as C-mitosis, lagging chromosomes and multipolar at ana-telophases. Also, BA induced vacuolated nuclei and irregular prophases. The induction of chromosomal stickiness and chromosomal aberrations such as bridges indicates its action on the chromosome. Also, the induced chromosomal bridges at ana-telophases indicates true clastogenic potential of this chemical. It may be concluded that BA causes toxic effect on root tip cells of Nigella sativa L. and Allium cepa L. and this toxicity induces different types of genic and chromosomal variations.

In this study we compared the cytological effect and chromosomal behavior of root meristems of Allium cepa, induced by ZnO bulk and ZnO nanoparticles (NP). Four different concentrations of ZnO bulk and ZnO nanoparticles (2.5, 5, 10 and 20 ppm) were used to treat the root tips at different durations (2, 4, and 6 hours). The influence of these treatments on germination percentage and radicle length as well as mitotic index and chromosomal aberration was investigated. Our results indicate that all applied concentrations of ZnO bulk and ZnO nanoparticles caused a reduction in seed germination percent and radicle growth, as well as in mitotic index (MI) of Allium cepa seeds as compared to control. These reductions were accompanied by increase in concentration and/or duration of treatment. The total percentage of chromosomal aberrations were variable, with the change in concentrations and duration of treatment. Both bulk ZnO molecules and ZnO nanoparticles, induced different types of chromosomal abnormalities such as micro-nuclei, disturbed chromosomes, chromosomal stickiness, laggards, bridges, chromosomal fragmentation and diagonal. These abnormalities indicates true clastogenic possibility of ZnO bulk and ZnO nanoparticles.

In the present study, the effect of various concentrations of cinnamon bark extracts (10-150%)for 6, 12 and 18 hrs duration was investigated on seed germination and radicle growth of Allium cepa and Vicia faba. Moreover, we achieved a genotoxicity study at cytological level in root meristems of both plants by means of traditional cytogenetic approach, to evidence possible alterations in mitotic activity, chromosomal aberrations, and micronuclei release. From these analyses it comes out that the cinnamon extract, after short-term exposure and under our experimental conditions, in both plants the germination percentage was significantly reduced with all treatments and radicle elongation was affected and significantly inhibited and the Allium cepa was more affected than Vicia faba. Both investigated criteria were concentration and treatment time dependent. The reduction was correlated with a decrease in the mitotic index where the lowest mitotic index value was found to be at 150% of extract treatment for 18 hrs in both plants. A dose-dependent increase A total mitotic aberrations was also observed according to concentration and time of treatment of the extract.. Significantly higher frequencies of cells with mitotic aberrations indicated the primary action of cinnamon to involve chromatin organization and mitoticspindles, leading to the induction of several abnormalities. The various abnormalities scored were irregular prophase, stickiness, C-mitosis, bridges, diagonal and lagging or vagrant chromosomes. Micronucleated cells were also observed at interphase and other phases. The induction of chromosomal aberrations that evidenced a cinnamon induced cytotoxic and genotoxic effect for both tested plants.

The effects of different treatments with zinc sulfate (Zn(2+)) on the cytology and growth of Nigella sativa and Triticum aestivum were investigated. Five concentrations of zinc sulfate ranging from 5 to 25mg/l were applied for 6, 12, 18, and 24h. The treatments reduced the germination percentages of N. sativa seeds and T. aestivum grains and inhibited the root growth of both plants. Concentrations higher than 25mg/l of Zn(2+) applied for 24h were toxic for both plants. The non-lethal concentrations of Zn(2+) showed an inhibitory effect on cell division in root tips of both plants and caused a decrease in their mitotic index values. The reduction in MI in root tips of T. aestivum was more evident than that of N. sativa. All treatments changed the frequency of mitotic phases as compared with the control values. The total percentage of abnormalities in N. saliva was more than that in T. aestivum. Zn(2+) treatments produced a number of mitotic abnormalities in dividing cells in root tips of both plants resulting from its action on the spindle apparatus such as C-metaphases, lagging chromosomes and multipolar anaphases and telophases. Also, Zn(2+) induced vacuolated nuclei and irregular prophases. The induction of chromosomal stickiness and chromosomal aberrations such as bridges and breaks indicates its action on the chromosome. These abnormalities (chromosome breaks and chromosomal bridges at ana-telophases) indicate true clastogenic potential of the ions tested.