Canton S laboratory wildtype lines (Bloomington Stock Center) and a K+ channel mutant seizure (seizurets1 a gift from Dr. Barry Ganetsky published in Titus et al. 1997) a homolog of human hERG were used in this study. Flies launched to the International Space Station and the corresponding ground controls were housed in polystyrene vials (75 x24 mm) with 10 ml of standard cornmeal-based fly food containing double the usual amount of 10% Tegosept and cellulose acetate plugs. Approximately 24 hours prior to launch 15 vials were each loaded with 10 virgin females and 5 male adult flies. Loaded vials were placed in a Plexiglas tray and inserted into a vented fly box (VFB) a modified version of a Nanoracks box. The VFB was placed into a canvas case for loading into the Dragon capsule. Launch of SpaceX CRS-3 occurred at 19:25 UTC on April 18 2014. Flies were kept in the VFB throughout the 30-day mission and were stored aboard the docked Dragon capsule that shared atmosphere with the ISS. The Dragon capsule unberthed at 13:26 UTC (Co-ordinated Universal Time) on May 18 2014 and re-entry into the Earth xe2 x80 x99s atmosphere occurred the same day at 19:05 UTC. Following retrieval of the Dragon capsule off the coast of Mexico the VFB was offloaded at Long Beach Port California and transported by car to La Jolla California in a climate-controlled vehicle. Surviving adult flies born on the ISS were collected from the vials at 23:30 UTC on May 20 2014. Data collection which included negative geotaxis assays heart function studies tissue collection for RNAseq and tissue preservation for immunohistochemistry was completed by 07:30 UTC on May 21 2014 on all microg spaceflown and corresponding ground control flies. The VFB was oriented such that the g xe2 x80 x90load was directed down into the food supply located at the bottom of the vials. This orientation was maintained throughout the entirety of the mission from point of transfer at the lab at NASA Kennedy Space Center through stowage on the Dragon capsule and again from Dragon un-berthing to opening of the VFB in the lab at SBP Medical Discovery Institute in La Jolla California. Ground control flies were prepared and reared under identical conditions in ground-based incubators with temperature and humidity controlled to levels recorded on the ISS.