Heavy metals are potent poisons for living cells. The reason for their toxicity in vivo remains uncertain but it is well known that they contribute to the accumulation of aberrant proteins (Chen and Piper, 1995, BBA, vol. 1268, pp. 59). The synthesis of heat shock proteins (hsp), a universal response of cells to heatshock, is also activated by treatments with heavy metals (Edelman et al., 1988, Plant Physiol., vol.86, pp.1048). Stressed cells also activate several components of the proteolytic system dependent on ubiquitin, that normally functions to turnover cytoplasmic and nuclear proteins. The involvement of this pathway on the response of the heat shock is well known and recently the resistance of yeast to cadmium has been related with the ubiquitin proteolytic pathway (Jungmann et al., 1993, Nature, vol. 361, pp. 369) In our work we followed the changes in both free ubiquitin and conjugated ubiquitin during the incubation of Lemna minor L. fronds in the presence of arsenite concentrations that confer thermotolerance to the plants. The observed increased levels of ubiquitin conjugates, detected by immunoblotting using antiubiquitin antibodies, suggests an involvement of the ubiquitin-mediated proteolytic pathway during arsenite treatment. This work was supported by grant PRAXIS XXI/BD/5699/95.
|Number of pages||1|
|Publication status||Published - 1997|