Zea mays L. protein changes in response to potassium dichromate treatments.

The plant metabolic response to heavy metal stress is largely unknown. The present investigation was undertaken to examine the influence of different concentrations of potassium dichromate on the Zea mays L. plantlets. A clear effect of chromium on maize plantlets growth and seed germination was observed strating from 100-300 ppm up to 1500 ppm. In this concentration range, chromium uptake was dependent on the concentration in the medium. Metallothioneins, involved in heavy metal binding, were measured by capillary electrophoresis (CE), and showed a dose-response induction. Protein profile analyzed by two-dimensional gel electrophoresis showed differential expression of several proteins. Identification of spots of upregulated proteins was performed by MALDI mass spectrometry. Results showed that proteins induced by heavy metal exposure are principally involved in oxidative stress tolerance or in other stress pathways. Induction of proteins implicated in sugar metabolism was also observed. Identification of factors involved in plant response may lead to a better understanding of the mechanisms involved in cell protection and tolerance. This information could be used to improve agricultural production and environmental quality.

Eruption-triggered avalanche, flood, and lahar at mount st. Helens--effects of winter snowpack.

An explosive eruption of Mount St. Helens on 19 March 1982 had substantial impact beyond the vent because hot eruption products interacted with a thick snowpack. A blast of hot pumice, dome rocks, and gas dislodged crater-wall snow that avalanched through the crater and down the north flank. Snow in the crater swiftly melted to form a transient lake, from which a destructive flood and lahar swept down the north flank and the North Fork Toutle River.