Effects of manganous sulphate on root growth,cell division,and nucleoli of Allium cepa

The effects of different concentrations of manganous sulphate on root growth,cell division, chromosome and nucleus morphplogy and nucleoli in root tip-cells of Allium cepa L. were studied. The concentrations of manganous sulphate used were 10-7,10-6,10-5 ,10-4,10-3, 10-2 and 10-1mol/L. The results indicated that manganese had a stimulatory effect on the root growth at lower concentrations (10-7 to 10-4mol/L). With increasing the concentration of Mn (10-3 to 10-1mol/L) and duration of treatment,manganese inhibited root growth and cell division, and had toxic effects on chromosomes,nuclei and nucleoli. Manganese Could induce mitotic irregularities,comprising c-mitosis,anaphase bridges and chromosome stickiness. The nuclei became irregular in shape and many micronuclei were scattered in the cytoplasm. Some similar silver-stained particulate materials were found scattered in the nucleus in root tip cells. The possible mechanism behind these phenomena is also briefly discussed.

Effects of Zn^（2＋） on root growth，cell division，and nucleoli of Allium cepa L．

The effects of different concentrations of Zn￣(2+)ion on root growth,cell division,and nucleoli of Allium cepa were studied. The test Zn￣(2+) ion concentration was made up from zinc sulphate (ZnSO4. 7H2O) ranging from 10￣(-7) to 10￣(-2) mol/L. The solutions were prepared in tap water (pH =6. 5).The results indicated that Zn￣(2+) could obviously inhibit root growth at concentrations from 10￣(-4)to 10￣(-2) mol/L.Roots treated with zinc sulphate showed the presence of c-mitosis, anaphase bridges,including sticky and fluidized bridges (at 10￣(-3) to 10￣(-2) mol/L) , chromosome stickiness, irregularly shaped nuclei, broken nuclei and micronuclei. A toxicity effect was also observed on the nucleoli using silver staining technique after 48h of treatment with 10￣(-4)to 10￣(-2) mol/L Zn￣(2+), e. g,the nucleolar particulate material scattered around the nucleoli in the nucleus of root tip cells.

镉对洋葱根生长和细胞分裂的影响

研究了不同浓度氯化镉溶液对洋葱根的生长,细胞分裂和染色体形态的影响.结果表明,随Cd^(2+)浓度增加,根的生长速率递减;随处理时间延长,每单位时间的根生长速度递减或停止,根尖细胞有丝分裂指数随Cd^(2+)的浓度增高和处理时间延长而递减.不同浓度Cd^(2+)都能引起染色体畸变,恢复培养后均能恢复生长。

铝(Al^(3+))对洋葱根生长和细胞分裂的影响

以洋葱(Allium cepa L.2n=16)为材料,研究不同浓度氯化铝(AlCl_3·6H_2O)溶液对根生长、根尖细胞有丝分裂和染色体形态的影响.研究结果表明,随着Al^(3+)浓度的增加,根的生长量递减,呈明显的负相关;随着处理时间的延长,每单位时间的生长量亦递减,甚至停止生长;在50～200ppm Al^(3+)处理下,根尖细胞有丝分裂指数随着Al^(3+)浓度增高而递减,随着处理持续时间的延长而递减;不同浓度的Al^(3+)处理都能引起染色体畸变,如,c-有丝分裂、染色体桥、染色体粘连等;恢复培养后各处理的鳞茎均能恢复生长.染色体畸变率降低.

氯化钠对分蘖葱头根尖细胞有丝分裂的影响及其致畸效应

以分蘖葱头根尖为试验材料,研究了氯化钠对分蘖葱头根尖的毒性效应。用不同浓度(0.05、0.1、0.2、0.3 mol/L)的氯化钠水溶液对分蘖葱头根尖细胞染毒12 h、24 h、48 h,观察分蘖葱头根尖细胞有丝分裂指数、微核率以及染色体畸变情况。结果表明:在试验剂量范围内,随着氯化钠水溶液浓度的升高,染毒时间增长,分蘖葱头根尖细胞的有丝分裂指数逐渐降低,染色体畸变率和微核率逐渐升高,并且均在氯化钠水溶液浓度为0.3 mol/L、染毒时间为48 h时达到最大值,说明氯化钠是一种胁迫因子。