Biological research is changing in interesting ways due to the advent of a number of new technologies. One such technology is microarrays. The problem at hand was figuring out what genes were being affected by a change in iron concentration in the microbe
Pseudomonas syringae, an important pathogen of tomatoes. The relative absence of iron (Fe) is a signal for the microbe that it is now in its host.
In the old days, one would make mutations in the microbe and then screen for those that had problems with Fe metabolism. This was a tedious process, taking many months in most cases, and giving limited results, as only a subset of genes involved with Fe would be found by any one screen or selection.
Now, a microarray, containing the entire gene collection of the microbe is available. The microbe is simply grown in the presence and absence of iron and microarray data is collected under both conditions. A comparison of the two arrays will indicate which genes had a change of expression. A simple experiment in this case, replaces years of work using classical genetics and reveals all the genes influenced by changes in iron concentration. The experiment is presented in a paper by
Bronstein et al [5].