Cellular Toxicity of Aluminum in Root Tips of Vicia faba L.

In order to further understand and confirm the cytological mechanism of Al on roots of V. faba, the toxic effects on root growth, cell division, nucleolus and nucleoproteins (nucleophosmin, nucleolin and fibrillarin) were investigated by silver staining method and indirect immunofluorescence. The results showed that Al had an inhibitory effect on root growth at concentrations of 50 and 100 mu M Al during the entire treatment (72 h) in comparison with control (p<0.05). The mitotic cells decreased, indicating that Al was accumulated predominantly in the meristem, where it disturbed cell division and resulted the inhibition of root growth. Al could induce c-mitosis, chromosome stickiness, lagging chromosome and chromosome bridges in root tip cells. C-mitosis and chromosome stickiness are two major types of chromosomal aberrations. Results from silver-staining indicated that Al could affect the nucleolus and induce extrusion of silver-staining nucleolar particles containing argyrophilic proteins from the nucleolus into the cytoplasm in root tip cells of V. faba. Evidence from indirect immunofluorescence microscopy demonstrated that silver-stained particles/material released from the nucleolus into the cytoplasm in the roots exposed to Al contained nucleophosmin, nucleolin and fibrillarin. The data obtained here can provide valuable information for monitoring and forecasting early effects of exposure to Al under realistic conditions.