MICROARRAY ANALYSIS: MORE ON BIOTECH SAFETY
Aug 25, 2008
In my March 20 post “ Organic and Biotech” I mentioned that most people probably don't know that many organic wheat varieties used for making organic pasta come from germplasm that was developed using mutation breeding i.e. introducing genetic variation by mutations caused by gamma rays.
I asked what is more radical or more unnatural- biotech corn or organic corn with germplasm that resulted from mutation induced techniques?
A recent article in the Proceedings of the National Academy of Sciences looks at changes in gene expression in plants that result from gene insertion ( biotech crops) vs mutagenesis ( conventional and organic crops). Basically, gene expression can be measured by mRNA levels. To risk criticism for oversimplifying the biology involved, the basic model for gene expression is as follows:
DNA ==> mRNA + other RNA ==> protein ( or expressed gene)
By measuring mRNA content, scientists can determine the level of expression of various genes. mRNA can be measured using microarray analysis. A microarray is a small chip that contains DNA or RNA fragments that can filter or capture DNA or RNA from a sample by bonding or ‘annealing’ to the sample DNA or RNA.
The annealing pattern can then be interpreted to measure gene expression. Again a simplification, but this method allows scientists to monitor the expression of thousands of genes simultaneously. When it comes to determining the unknown and possibly adverse effects of gene insertion, or any plant breeding method, microarray analysis is a powerful tool.
In the article itself, microarray analysis revealed that unintended alterations were much more extensive in mutagenized plants vs biotech varieties.
‘Microarray analyses reveal that plant mutagenesis may induce more transcriptomatic changes than transgene insertion’
PNAS March 4,2008 vol 105 no 9