PM05 Aquatic Vertebrate/Invertebrate Toxicology
Exhibit Hall
8:00 AM - Monday, 10 November 2003
(PM073) The Effects of Various Concentrations of Aluminum on the Growth and Development of Arabidopsis thaliana.
Hamissou, Mijitaba1, Goodman, Tomiko1, Morefield, Heather1, Willingham, Jason1, 1 Biology Department, Jacksonville State University, Jacksonville, Alabama, USA
ABSTRACT- Aluminum toxicity is a major factor limiting plant growth and development and contributes to the acidification of aquatic environment. It is among the most widespread stresses in plants. Aluminum can have an adverse effect on plants and animals within a short period of exposure. Plant species and animals differ in their mechanisms enabling them to grow and reproduce despite elevated concentrations of aluminum. The mechanisms of aluminum tolerance in animals are not well understood. Many plant species are thought to tolerate high concentrations of aluminum by secreting organic acids at the root zones. These organic acids are believed to chelate Al3+ and transform it into a less toxic form Al2+. The objective of this study is to investigate the molecular responses of arabidopsis plants and germinating embryos to various concentrations of aluminum. The experimental procedures consisted of growing arabidopsis plants in soil mixture in a growth chamber for 4 weeks before exposing then to different concentrations of AlCl3. In other experiments, seeds were germinated and maintained on 6% agar plates in a growth chamber at 25oC, 18 hour-light and 6 hour-dark for 36 hours before transferring them to new agar plates containing different concentrations of AlCl3. 6, 12, and 24 hours after exposure, leaf, root, and whole seedling samples were taken for proteins extraction by differential centrifugation. The proteins were biochemically assayed and analyzed by SDS-PAGE and Western blot. Preliminary data indicated a repression of high molecular weight proteins, an increase in dehydrogenase activities as aluminum concentration increases. We also observed that malate dehydrogenase appears to be the most abundantly secreted enzymes by arabidopsis under aluminum toxicity.
Key words: Arabidopsis, Aluminum, Dehydrogenase, Toxicity