Studying triplet repeat expansion in Arabidopsis at high temperatures could allow scientists to investigate similar disorders in humans. Triplet Repeat Expansion in Arabidopsis
While studying Bur-0, a wild strain of Arabidopsis thaliana, Dr. Sureshkumar Balasubramanian and his colleagues discovered that at warmer than normal conditions the plant did not flower and produced misshapen leaves. This ‘greenworm’ or ‘irregularly impaired leaves’ (iil) phenotype was discovered to have resulted from a TTC/GAA triplet repeat expansion in a gene involved in the synthesis of amino acids – isopropyl isomerase large subunit 1 (IIl1).
The study found that the triplet repeats occur in non-coding regions and result in massive expansions which hinder DNA polymerase. There are no changes in amino acids, but the decline in transcription leads to less protein being produced. According to Balasubramanian, the discovery of this genetic defect in Bur-0 provides an important research opportunity for scientists: “Because these expansions are so massive, it’s difficult to engineer them genetically to study … So in the absence of other systems, we feel that this one provides a very nice tool for study.”
Implications for Human Triple Repeat Disorders
Using Bur-0 as a model for research into triplet repeat disorders could potentially allow for investigation of such disorders in humans. In addition to disorders involving repeats in non-coding areas, such as in Bur-0, there are a number of disorders where triplet repeat expansions occur in the exons. These disorders affect glutamine or alanine levels. Huntington’s disease, Fragile X and Friedreich’s ataxia are all examples of human disorders resulting from triplet repeat expansion.
The results of this study have recently been published by Balasubramanian and his colleagues in Science, and certainly seem to suggest the merit of further investigation into triplet repeat expansions. Balasubramanian commented that: “Obviously there is an interest in a medical applications but the basic knowledge in terms of understanding at the population level is also important.”
Clearly, research into this little weed has a lot of potential.
Dr. Balasubramanian is currently working in the School of Biological Sciences at the University of Queensland.
Published by: 41617522
Sources
Article:
McDonald, K 2009, Hot Arabidopsis and its Triplet Trouble, Australian Life Scientist, viewed 16 May 2009, <http://www.biotechnews.com.au/article/303174/hot_arabidopsis_its_triplet_trouble?pp=4&fp=4&fpid=1012>.
Picture :
<http://www.missouriplants.com/Whitealt/Arabidopsis_thaliana_plant.jpg>.
