s4206010
For 50 years a popular rodenticide has been slowly growing redundant. The study and use of Warfarin began in 1950 after the symptoms of non-coagulating blood and the resulting deaths were observed in bovines. The warfarin acts by repressing the activity of the vitamin K reductase (VKOR) resulting in retardation of inhibitors of blood coagulation.
Several species of rats and mice were collected in a number of countries over four years. Scientists sequenced the VKORC1 genes of rodents that were trapped in anticoagulant prevalent areas. Many of these rodents exhibited differing genetic adaptations at the molecular level which reduced the effectiveness of Warfarin.
Other studies of the rats further proved that the VKORC1 genes were responsible for the growing resistance against warfarin. ‘Field investigations of the relative fitness of warfarin-resistant rats on a farm in Shropshire (UK) showed that when selection pressure from the anti-coagulant use was removed, frequency of the warfarin resistance gene fell from 80 to 33% over 18 months.’
These rats evolved through a process of natural selection, where those that survive, survive to sire offspring which in many cases would carry their parents resistant genes. This process is also necessary for the survival of many bacteria and relies on their rapid rate of reproduction.
http://www.biomedcentral.com/1471-2156/10/4
http://en.wikipedia.org/wiki/Warfarin
http://en.wikipedia.org/wiki/Anticoagulant
