Comparative analysis of Drosophila melanogaster and Caenorhabditis elegans gene expression experiments in the European Soyuz flights to the International Space Station.

The European Soyuz missions have been one of the main routes for conducting scientific experiments onboard the International Space Station, which is currently in the construction phase. A relatively large number of life and physical sciences experiments as well as technology demonstrations have been carried out during these missions. Included among these experiments are the Gene experiment during the Spanish "Cervantes" Soyuz mission and the ICE-1st experiment during the Dutch "Delta" mission. In both experiments, full genome microarray analyses were carried out on RNA extracted from whole animals recovered from the flight. These experiments indicated relatively large scale changes in gene expression levels in response to spaceflight for two popular model systems, Drosophila melanogaster (Gene) and Caenorabditis elegans (ICE-1st). Here we report a comparative analysis of results from these two experiments. Finding orthologous genes between the fruit fly and the nematode was far from straightforward, reducing the number of genes that we could compare to roughly 20% of the full comparative genome. Within this sub-set of the data (2286 genes), only six genes were found to display identical changes between species (decreased) while 1809 genes displayed no change in either species. Future experiments using ground simulation techniques will allow producing a better, more comprehensive picture of the putative set of genes affected in multicellular organisms by changes in gravity and getting a deeper understanding of how animals respond and adapt to spaceflight.

Drosophila melanogaster, a model system for comparative studies on the responses to real and simulated microgravity.

A key requirement to enhance our understanding of the response of biological organisms to different levels of gravity is the availability of experimental systems that can simulate microgravity and hypergravity in ground-based laboratories. This paper compares the results obtained from analysing gene expression profiles of Drosophila in space versus those obtained in a random position machine (RPM) and by centrifugation. The correlation found validates the use of the RPM simulation technique to establish the effects of real microgravity on biological systems. This work is being extended to investigate Drosophila development in another gravity modifying instrument, the levitation magnet.