Toxic models on the fly

15 September 2009

The fruit fly Drosophila melanogaster is one of the most commonly used model organisms in biology, and has been used extensively to study bacterial infection.

Now scientists at the University of Bath have found a way to use Drosophila embryos to track the way bacterial toxins work in real time at the critical early stages of infection - a system that could prove useful in studying other pathogens and their toxins.

The researchers looked at how embryonic Drosophila haemocytes (part of the organism's immune system) responded to disease-causing and non-disease-causing bacteria, using time-lapsed microscopy.

While the haemocytes recognised and ingested non-disease-causing E. coli with no problems, the disease-causing bacterium P. asymbiotica made them instantly 'freeze' and caused significant rearrangement of their structure.

The scientists were able to reproduce this effect using a purified toxin found in P. asymbiotica, by either injecting it into the haemocyte or introducing it via bacteria expressing the toxin gene. This, together with studies of Drosophila mutants - such as those with haemocytes deficient in their ingestion machinery - suggests that the entry of the toxin into the cell is key to its method of action.

Image: Drosophila melanogaster. Credit: Image Editor on Flickr

Reference

Vlisidou I et al. Drosophila embryos as model systems for monitoring bacterial infection in real time. PLoS Pathog 2009;5(7):e1000518.