Humans may claim to have invented the hypodermic needle, but in fact, nature was plying them long before we came along. Through a vanishingly thin ‘needle’, certain viruses are able to infect bacteria, such as this Escherichia coli cell (large circle). The virus uses six fibres to rest on the bacterium, like a space shuttle on the moon, before piercing the surface with its tail (faded line emerging from small circle nearest bottom). Then, just as a doctor's syringe delivers its payload, the virus uses this tube to inject the unfortunate E.coli cell with its own DNA – the genetic code of life. The cell then unwittingly creates thousands more virus copies from this blueprint, which eventually burst out, killing the bacterium. Understanding this process is important because viruses that attack bacteria in this way could offer a weapon against drug-resistant strains.
Written by Jan Piotrowski
BPoD stands for Biomedical Picture of the Day. Managed by the MRC London Institute of Medical Sciences 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.