Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Pb-induced cellular defense system in the root meristematic cells of Allium sativum L | Jiang and Liu BMC Plant Biology 2010 10 40 http 1471-2229 10 40 BMC Plant Biology RESEARCH ARTICLE Open Access Pb-induced cellular defense system in the root meristematic cells of Allium sativum L Wusheng Jiang1 Donghua Liu2 Abstract Background Electron microscopy EM techniques enable identification of the main accumulations of lead Pb in cells and cellular organelles and observations of changes in cell ultrastructure. Although there is extensive literature relating to studies on the influence of heavy metals on plants Pb tolerance strategies of plants have not yet been fully explained. Allium sativum L. is a potential plant for absorption and accumulation of heavy metals. In previous investigations the effects of different concentrations 10-5 to 10-3 M of Pb were investigated in A. sativum indicating a significant inhibitory effect on shoot and root growth at 10-3 to 10-4 M Pb. In the present study we used EM and cytochemistry to investigate ultrastructural alterations identify the synthesis and distribution of cysteine-rich proteins induced by Pb and explain the possible mechanisms of the Pb-induced cellular defense system in A. sativum. Results After 1 h of Pb treatment dictyosomes were accompanied by numerous vesicles within cytoplasm. The endoplasm reticulum ER with swollen cisternae was arranged along the cell wall after 2 h. Some flattened cisternae were broken up into small closed vesicles and the nuclear envelope was generally more dilated after 4 h. During 24-36 h phenomena appeared such as high vacuolization of cytoplasm and electron-dense granules in cell walls vacuoles cytoplasm and mitochondrial membranes. Other changes included mitochondrial swelling and loss of cristae and vacuolization of ER and dictyosomes during 48-72 h. In the Pb-treatment groups silver grains were observed in cell walls and in cytoplasm suggesting the Gomori-Swift reaction can indirectly evaluate the Pb effects on plant cells. Conclusions Cell walls can .
