Effects of Cadmium Stress on Seed Germination, Seedling Growth and Seed Amylase Activities in Rice (Oryza sativa)

Two rice varieties, Xiushui 110 with high cadmium (Cd) tolerance and Xiushui 11 with low Cd tolerance were used to study the effects of Cd stress on seed germination, seedling growth and amylase activities. The low cadmium concentration had little effect on seed germination rate. However, cadmium stress could significantly inhibit plumule and radicle growth, especially for radicle growth. Germination index, vigour index, radicle length and amylase activities of Xiushui 11 decreased more significantly with the increasing cadmium level compared with Xiushui 110. The cadmium content in seedlings of Xiushui 11 was higher than that in Xiushui 110 when the cadmium concentration exceeded 5 μmol/L, which caused lower mitotic index in root tips and amylase activities, and more serious cadmium toxicity in Xiushui 11.

Mutagenic effects of chromium trioxide on root tip cells of Vicia faba

In this study on the mutagenic effects of different concentrations of chromium trioxide (CrO3) on Vicia faba root tip, micronucleus assay and chromosome aberration assay were used to determine the mitotic indexes, micronucleus rate and chromosome aberration rate of Vicia faba root tip cells. The results showed that the effects of CrO3 concentration on the mitotic indexes were complicated. CrO3 increases the micronucleus rate of Vicia faba root tip cells. It was found that within certain range of CrO3 concentration the micronucleus rate increased systematically with increased concentration of CrO3, but that the micronucleus rate decreased at higher level of CrO3 and that CrO3 also caused various types of chromosome aberration at a rate which increased systematically with increased concentration of CrO3. We concluded that CrO3 has significant mutagenic effect on Vicia faba root tip cells.

Allelopathic Potential of Rice （Oryza sativa L.） Cultivars on Barnyard Grass （Echinochloa crus-galh~

Laboratory and greenhouse studies were conducted to assess the allelopathic potential of 12 rice cultivars on barnyard grass. Polyethylene glycol （PEG） was used to determine the influence of osmotic potential on the bioassay materials. Effect of different concentrations of stem, root, and leaf extracts of rice cultivars on seed germination, radicle and primary shoot length of barnyard grass seedlings, and rate of respiration of root pieces were investigated in the laboratory experiments. Shoot height and dry weight of weed stands were studied in the greenhouse, Also total peroxidase activity, chlorophyll pigment and mitotic index were determined. Results indicated that, among rice cultivars, Mehr, Tarom-mahali, G3, Nemat, and Shahpasand caused the most inhibition effects on investigated factors. Amol-3 showed the least negative effects on growth of seedlings and stands of barnyard grass. In laboratory, the Mehr cultivar demonstrated the maximum inhibitory effects by reducing barnyard grass seed germination percentage （88%）, radicle length （100%）, primary shoot length （83%）, and root respiration （85%） Cell division, expressed as mitotic index, was significantly reduced in the presence of rice aqueous extracts. Mehr cultivar had higher inhibitory effect on mitosis compared to Amol-3. In greenhouse, the same cultivar showed the maximum inhibitory effect by reducing barnyard grass height （45%） and dry weight （64%）. With increase in extract concentration, the inhibitory effect increased. Leaf extract from rice plants was more effective compared with the root and stem extracts. Comparison of rice cultivars and PEG indicated that any reduction in germination and growth of barnyard grass using rice extract concentrations of 5% and 10% must have been the result of allelochemicals in the extracts. Lower extract concentrations showed a more pronounced inhibitory effect in the laboratory as compared to the greenhouse studies. These results suggest that rice leaf extracts may be a source of natural herbicide.

Ontogeny of rat chondrocyte proliferation:studies in embryo,adult and osteoarthritic (OA) cartilage

The aim of this work was to study the ontogeny of chondrocyte cell division using embryo, adult and osteoarthritic(OA) cartilage. We searched for mitosis phases and performed a comparative evaluation of mitotic index, basic fibro-blast growth factor b (FGFb), transforming growth factor β1 (TGF-β1) receptors, cyclin dependent kinase (CDK1)and Cyclin-B expression in fetal, neonate, 3, 5, 8 weeks old rats and experimental OA. Our results showed that mitosisphases were observed in all normal cartilage studied, although, we found a decrease in mitotic index in relation to tissuedevelopment. No mitosis was detected in OA cartilage. We also found a statistical significant reduction in cell number inOA cartilage, compared with the normal tissue. Furthermore, FGFb and TGF-β1 receptors diminished in relation totissue development, and were very scarce in experimental OA. Western blot assays showed CDK-1 expression in allcases, including human-OA cartilage. Similar results were observed for Cyclin-B, except for 8 weeks, when it was notexpressed. Our results suggest that cell division seems to be scarce, if not absent within the OA cartilage studied.Nevertheless, the existence of factors essential for cell division leaves open the question concerning chondrocyteproliferation in OA cartilage, which is likely to be present in the early stages of the disease.

Enhancement of Sister Chromatid Exchanges in Peripheral Blood Lymphocytes of Thyroid Cancer Patients in Vitro

The aim of our study was to determine the chromosomal fragility of thyroid cancer patients in vitro. The cytogenetic methodology used in our study, was the SCEs （sister chromatid exchanges technique）. FPG （fluorescence plus giemsa） method, was used in order to dye chromosomes. PRI （proliferation rate index）, MI （mitotic index）, AGT （average generation time） and PDT （population doubling time） were also counted. CPT-11 （Irinotecan）, an original alkyliotic agent, was used in our experiments as a positive control. Samples from 19 thyroid cancer patients and 13 healthy donors were controlled. The levels of SCEs were analyzed as a quantitative index of genotoxicity and the PRI and the MI were estimated as qualitative indices of cytostaticity and cytotoxicity, respectively. After CPT-11 addition in human lymphocytes cultures, the chromosomes of the cancer patients had a significant increase of the mean SCEs frequency. PRI and MI of treated with CPT- 11 and untreated lymphocytes of thyroid cancer patients were significantly lower than those of healthy donors, The results suggested that peripheral lymphocyte chromosomes of cancer patients are highly fragile and the alkyliotic agents increase their genetic instability. It appears that the increased SCE levels in peripheral blood lymphocyte chromosomes of thyroid cancer patients often result in chromosomal brittleness,

The Effect of Gnaphafium oxyphyllum var. natalie on Cancer and Blood Cells

Gnaphalium oxyphyllum DC is a medicinal plant whose common uses by Mexican people include the treatment of cancer. The toxicity of the aqueous and organic fractions as well as the aqueous decoction of G. oxyphyllum var. natalie F. J. Espinosa were assessed on three human cancer cell lines as well as in blood cells in healthy human lymphocyte cultures. Cytotoxic activity was assessed by the Sulforhodamine B method on HeLa （human cervical carcinoma）, T47D （human breast carcinoma） and 22Rvl （human prostate carcinoma cancer）. Colchicine was used as positive control. The decoction was also tested on lymphocytes from healthy donors through the mitotic index as biomarker. We used whole blood for these cultures and estimated the effect of the extract on platelets, leukocytes and erythrocytes. The aqueous decoction was cytotoxic （EDs0 〈 20 μg/mL） on the three cancer cell lines. The mitotic index in the exposed lymphocyte cultures did not significantly differ from the control nor the blood counts showed any difference between the experimental and control cultures. These results prove that the toxic effect of the aqueous decoction of G. oxyphyllum var. natalie is specific for cancer cell lines.

How to use progestin in hormone replacement therapy: an animal experiment

Objective To determine whether continuous or cyclic hormone replacement therapy (estrogen and progestogen) is better.Methods One hundred and forty Sprague-Dawley rats were randomly divided into seven groups. The 1st and 2nd groups were normal estrous and ovariectomy (OVX) controls. Treatment of the other groups imitated the clinical regimen (continuous and cyclic) with estradiol valerate (E2V) and medroxy progesterone (MPA) in different ratios of combination. The rats were sacrificed and sections of uterus were stained with HE and histochemical metheds to detect mitosis and proliferating cell nuclear antigen (PCNA), respectively. The mitotic index (MI) and PCNA index were calculated.Results The MI and PCNA index were similar in luminal and glandular cells. Both markers were low in the two control groups. When E2V was given for 1 to 6 days, both the MI and PCNA index increased with duration of treatment. When MPA was added, both markers were reduced to a very low level. In the continuous regimen, both markers decreased as the MPA dosage increased. The ratio of E2V∶MPA=1∶0.5 was enough to suppress markers to a low level similar to that of normal estrous rats. A further increase in the ratio to 1∶1.0 showed no further decrease in PCNA index. In the cyclic regimen, MPA was added for the last 5 days. The mitotic index reached a significantly low level near 0 in all ratios, but the PCNA index in each subgroup was still as high as the positive control, even though the dosage of MPA was increased several times to 1∶8.0. When MPA was added for the last 10 days, the PCNA index at a ratio of 1∶4.0 could be reduced to a low level.Conclusion The results of this study suggest that the continuous regimen was better than the cyclic regimen in postmenopausal hormone replacement therapy (HRT). Progestin should be given for at least 10 days in the cyclic regimen.

Antioxidants in aqueous extract of Myristica fragrans(Houtt.) suppress mitosis and cyclophosphamide-induced chromosomal aberrations in Allium cepa L.cells

In this study, freeze-dried water extract from the leaves of Myristica fragrans （Houtt.） was tested for mutagenic and antimutagenic potentials using the Allium cepa assay. Freeze-dried water extract alone and its combination with cyclophosphamide （CP） （50 mg/kg） were separately dissolved in tap water at 500, 1000, 2000, and 4000 mg/kg. Onions （A. cepa） were suspended in the solutions and controls for 48 h in the dark. Root tips were prepared for microscopic evaluation. 2,2-Diphenyl-l-picrylhydrazyl （DPPH） free radicals＇ scavenging power of the extract was tested using butylated hydroxyanisole （BHA） and butylated hydroxytoluene （BHT） as standards. Water extract of Myristica fragrans scavenged free radicals better than BHA, but worse than BHT. The extract alone, as well as in combination with CP suppressed cell division, and induced chromosomal aberrations that were insignificantly different from the negative control （P≤0.05）. However, cytotoxic and mutagenic actions of CP were considerably suppressed. The observed effects on cell division and chromosomes of A. cepa may be principally connected to the antioxidant properties of the extract. The obtained results suggest mitodepressive and antimutagenic potentials of water extract of the leaves of M. fragrans as desirable properties of a promising anticancer agent.

Cytogenetic studies of chromium(Ⅲ) oxide nanoparticles on Allium cepa root tip cells

The current study evaluates the cytogenetic effects of chromium（Ⅲ） oxide nanoparticles on the root cells of Allium cepa.The root tip cells of A.cepa were treated with the aqueous dispersions of Cr2O3 nanoparticles（NPs） at five different concentrations（0.01,0.1,1,10,and 100 μg/m L） for 4 hr.The colloidal stability of the nanoparticle suspensions during the exposure period were ascertained by particle size analyses.After 4 hr exposure to Cr2O3 NPs,a significant decrease in mitotic index（MI） from 35.56%（Control） to 35.26%（0.01 μg/m L）,34.64%（0.1 μg/m L）,32.73%（1 μg/m L）,29.6%（10 μg/m L） and 20.92%（100 μg/m L） was noted.The optical,fluorescence and confocal laser scanning microscopic analyses demonstrated specific chromosomal aberrations such as-chromosome stickiness,chromosome breaks,laggard chromosome,clumped chromosome,multipolar phases,nuclear notch,and nuclear bud at different exposure concentrations.The concentration-dependent internalization/bio-uptake of Cr2O3 NPs may have contributed to the enhanced production of anti oxidant enzyme,superoxide dismutase to counteract the oxidative stress,which in turn resulted in observed chromosomal aberrations and cytogenetic effects.These results suggest that A.cepa root tip assay can be successfully applied for evaluating environmental risk of Cr2O3 NPs over a wide range of concentrations.

Effects of the Application of Different Concentrations of NaN3 for Different Times on the Morphological and Cytogenetic Characteristics of Barley （Hordeum vulgate L.） Seedlings

Sodium azide （NAN3） has been used in many biological studies as a mutagen. In the present study, the morphological and cytogenetic effects of NaN3 on barley （Hordeum vulgare L.） seedlings were investigated. Seeds of barley were treated with different concentrations of NaN3 （0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 mmol/L） and applied for different periods of time （3 and 4 h）. Parameters investigated, except for the mitotic index, were determined on Days 7 and 14. Increasing concentrations of NaN3 affected germination rates on Days 7 and 14 following application for 3 and 4 h. Although the length of the roots and leaves was affected by treatment with NaN3 on Day 14 of the germination period, coleoptile length was affected by NaN3 treatment on Day 7. Increasing concentrations of NaN3 and increased treatment period decreased the mitotic index compared with the untreated control. The inhibitory effects of NaN3 on the mitotic index indicate that NaN3 can have genotoxic and mutagenic effects on barley seedlings.

Assessing combined toxic effects of tetracycline and P25 titanium dioxide nanoparticles using Allium cepa bioassay

Usage of titanium dioxide nanoparticles(TiO_(2) NPs)and tetracycline(TC)has increased significantly in the present era.This leads to their release and accumulation in the environment.Both the compounds,individually,can have adverse toxic effects on the plants.Their binary mixtures can increase this degree of damage.The present study aimed to evaluate the toxicity of both the contaminants in individual and binary mixtures in Allium cepa.Further,the toxicity of TiO_(2) NPs upon UVA pre-irradiation was also measured.Results showed that UVA pre-irradiated NPs(UVA-TiO_(2) NPs)had a significant decrease in cell viability than their non-irradiated counterparts(NI-TiO_(2)),denoting an increase in photocatalytic activity upon UVA pre-irradiation.Very low concentrations of TC(EC10=0.016µmol/L)mixed with TiO2 NPs significantly increased the toxicity for both UVA-TiO_(2) and NI-TiO_(2) NPs.Intracellular ROS generation was significantly high for UVA-TiO_(2) NPs.However,TC did not have any effects on ROS production.Both the compounds exhibited genotoxic potential in A.cepa.Different chromosomal abnormalities like anaphase bridges,telophase bridges,laggard chromosomes,binucleate cells,etc.were observed.The binary mixture of UVA-TiO_(2) NPs and TC showed the highest chromosomal aberrations(64.0%±1.26%)than the mixture with NI-TiO_(2) or the individual contaminants.This decreased significantly after recovery(46.8%±1.92%),denoting the self-repair processes.This study proved that UVA-TiO2 NPs were more toxic and could be enhanced further when mixed with a sub-lethal concentration of TC.This work will help to assess the risk of both compounds in the environment.