We chose to measure gene expression at the mRNA level since the technique to do this, called microarray analysis, is a highly advanced and convenient way to quantitatively measure the expression of every gene in a single experiment, said Wilson, who coordinated the teams molecular profiling efforts for the Nickerson lab, and played a central role in the performance of these experiments, including data analysis. It is a very powerful technique that was very applicable to the spaceflight experiment. The isolation of mRNA poses particular challenges since it is very sensitive to degradation, but we designed the experiment using a fixative that preserved the mRNA very well.
After logging in millions of miles in space, the invaluable and well-traveled bacterial samples were analyzed back on Earth, and for the protein profiling studies, were taken to the University of Arizonas core proteomics facility at its Center for Toxicology to measure the level of every protein that had been subjected to space flight.
Working with the UA group was great and we obtained very nice data that complemented the microarray analysis very well, said Wilson. Keep in mind also that our body of mRNA and protein expression data from this experiment is precious, since comprehensive analysis of an organisms molecular genetic response to space flight is very rare.
Compared to bacteria that remained on earth, the space-traveling Salmonella had changed expression of 167 genes. After the flight, animal virulence studies showed that bacteria that were flown in space were almost three times as likely to cause disease when compared with control bacteria grown on the ground.
The study discovered that an important regulatory protein, Hfq, may be a key molecule responsible for the increased virulence due to space flight. Hfq is a protein that binds to and regulates a number of regulatory RNAs, which in turn, control gene expression, said Nic
|Contact: Joe Caspermeyer|
Arizona State University