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The genetic secrets of rats

Some rats are resistant to the poisons used to try and eradicate them, while others die as planned. Scientists at the Faculty of Agricultural Sciences at the University of Aarhus are trying to map the differences in genetic expression between resistant and receptive rats.

Rats may carry a large number of bacteria and viruses that pose a health risk to people and to other animals. They may also cause substantial material damage to buildings, roads and sewers. It is therefore the duty of the local governments to control these harmful rodents.

Unfortunately, some rats are able to make a meal of rat poisons without any ill effects they have become resistant to some of the more common rat poisons, and this is not conducive to effective rat control. Scientists at the Dept. of Integrated Pest Management at the University of Aarhus are therefore studying the genetic differences between the rats that are killed by the poisons and the rats that are resistant to them.

- In order to control resistance we have to know why rats become resistant, says PhD student Mette Drude Kjr Markussen at the Department of Integrated Pest Management. She is comparing receptive and resistant rats to see if there are any genetic differences. To this end she uses a so-called gene chip. The chip stores sequences encoding for certain rat genes, primarily a number of detoxification genes, and this enables any difference in the genetic expression of receptive and resistant rats to be measured.

- The detoxification gene is used by both rats and humans to aid the organism during a poisoning event. A couple of the so-called cytochrome P450 genes from this group of genes turn out to have a higher expression level in resistant rats. It therefore appears that part of what infers resistance in rats is how its detoxification genes are expressed, she explains.

- The knowledge we obtain in this study can be used to understand resistance in rats and hopefully be used in the organisation of future control strategies, says Mette Drude Kjr Markussen.

For further information please contact:
Mette Drude Kjr Markussen, Dept. of Integrated Pest Management, Faculty of Agricultural Sciences, University of Aarhus, telephone: +45 8999 3947, e-mail: [email protected].

Tuesday 10 April 2007 | Communication Unit