Exposure of Arabidopsis thaliana to Caesium137

1
Exposure of Arabidopsis thaliana to Caesium-137
Graham Hickman
2
Caesium-137

• Radioactive isotope of Caesium (Cs).
• Product of nuclear fission with a 30.23 year half
  life.
• Now the Principal radiation source of soil
  contaminated by the Chernobyl disaster.

3
Method3

• A. thaliana plants grown for one week.
• Transferred to plant medium containing low levels
  of Caesium-137 (controls to medium with no
  radioactivity) and left for further two weeks.
• Levels of Caesium-137 are chosen according to
  research and are reflecting occurring levels
  found in radioactively contaminated soil.
• The plants are then harvested for shoot and root
  samples before being hybridised onto ATH1 chips.

4
Experimental Results
5
Analysis of Shoot
Fold Difference 1.5, P-value Cut-off 0.05
6
Analysis of Root
7
Clustering
8
What's Changing?

• Roots found to have an increase in expression for
  genes related to ion homeostasis, plant stress
  e.g. UV radiation response.
• Root genes that were found to decrease in
  expression were related to metabolism and
  signalling.
• Shoot genes found to have a significant increase
  in expression involved in superoxide metabolism
  and response to metal ions. Only one unclassified
  gene decreased expression.
• No cross-over was found between significantly
  changing genes between root and shoot samples.

9
Conclusions

• Exposure to Caesium-137 causes a change in
  expression for a variety of genes in comparison
  to the control.
• Root and shoot tissue has responded differently
  to exposure to Caesium-137.
• Roots shows greater variation in expression and
  greater number of genes affected when compared
  with shoots.
• Increase in expression in stress and ion response
  genes, decrease in expression of a variety of
  metabolic and cell signalling genes.

10
Phytoremediation.

• Phytoremediation is the use of plants as a
  treatment for contaminated soils.
• Potential to use plants to remove Caesium-137
  from soil, for example at the Chernobyl site
  (sunflowers already in use for Uranium1).
• Brassicales have been identified as a taxa which
  generate high internal concentrations of Cs2.
• A. thaliana work could be used as a model for
  understanding phytoremediation in Brassicales
  (perhaps other plants).
• Explore results to get a better understanding of
  mechanism of Cs uptake and responses to radiation
  in plants.

11
Credits.

• Meagher, RB (2000). "Phytoremediation of toxic
  elemental and organic pollutants". Current
  Opinion In Plant Biology 3 (2) 153162.
• Willey. N.J, Tang. S and Watt. N.R (2005).
  Predicting Inter-Taxa Differences in Plant
  Uptake of Cesium-134/137. Journal of
  environmental quality 34 (5) 1478-1489.
• http//affymetrix.arabidopsis.info/narrays/experim
  entpage.pl?experimentid324
• Thanks to wikipedia editors for the nice images!

12
Any Questions?