Life never stands still, and all living species are evolving over time. While evolutionary processes are usually pretty slow, one area where the pace of change picks up is between pathogens – namely viruses, bacteria and fungi – and the organisms they infect. It's like a genetic arms race with the host's immune system shifting and changing to fight off any infections, while the invaders becomes ever more clever at sneaking past its defences. These little red rods are Bacillus thuringiensis bacteria, busily infecting the body of a millimetre-long nematode worm and seen down a fluorescence microscope. By taking a closer look at the genes involved on both sides of this biological warfare, using worms and their attackers as a model system in the lab, researchers are starting to unpick the complex interactions between pathogens and their hosts as they evolve together, locked forever in their unending struggle.
Written by Kat Arney
BPoD stands for Biomedical Picture of the Day. Managed by the MRC Clinical Sciences Centre the website aims to engage everyone, young and old, in the wonders of biomedicine. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.