Environmental and facility conditions promote singular gravity responses of transcriptome during Drosophila metamorphosis

Genome-wide transcriptional profiling showed that reducing gravity levels in the International Space Station (ISS) causes important alterations in Drosophila gene expression intimately linked to imposed spaceflight-related environmental constrains during Drosophila metamorphosis. However, simulation experiments on ground testing space-related environmental constraints, show differential responses. Curiously, although particular genes are not common in the different experiments, the same GO groups including a large multigene family related with behavior, stress response and organogenesis are over represented in them. A global and integrative analysis using the gene expression dynamics inspector (GEDI) self-organizing maps, reveals different degrees in the responses of the transcriptome when using different environmental conditions or microgravity/hypergravity simulation devices These results suggest that the transcriptome is finely tuned to normal gravity. In regular environmental conditions the alteration of this constant parameter on Earth can have mild effects on gene expression but when environmental conditions are far from optimal, the gene expression is much more intense and consistent effects. We compare the effects over the gene expression profile of Drosophila melanogaster during metamorphosis (3-4 days-long experiments) to altered gravity conditions into three GBF ("Ground Based Facilities" for micro/hyper- gravity simulation) using whole genome microarray platforms. In addition we perform this series of experiments including or not two environmental constrains to the system, a cold step of three days at 12C (ΔT) and a containment of the samples in a chamber that limitate the amount of available oxygen (↓O2). Descriptions of different GBFs ("treatments"): LDC means "Large Diameter Centrifuge". Samples can be placed under three conditions: inside LDC (at certain g level), at the LDC rotational control and at external 1g control (outside the LDC). RPM means "Random Positioning Machine". Samples can be placed under two conditions: inside RPM (at nearly 0g, Microgravity level) and at external 1g control (outside the RPM). At the magnet, means INSIDE the Magnetic levitator (another GBF). Samples can be placed under four conditions: inside Magnet 0g* (at microgravity with magnetic field), inside Magnet at 1g* (internal control with magnetic field) or inside the magnet 2g* (at hypergravity with magnetic field) and at external 1g control (outside the magnet)