Transcriptomic analysis of liver from mice subjected to simulated spaceflight euthanasia freezing and tissue preservation protocols

Multiple interacting factors were investigated: 1) To understand how euthanasia protocols affect gene expression when mouse carcasses are slow frozen mice were euthanized by either euthasol injection ketamine/xylazine injection or CO2 inhalation and carcasses slow frozen on dry-ice mimicking carcass preservation in the MELFI on the ISS. Carcasses were thawed and RNA extracted from livers; 2) To understand how carcass preservation protocols affect gene expression mice were euthanized with euthasol and carcasses preserved by flash freezing in liquid nitrogen slow freezing on dry ice or immersion in RNAlater following three-way segmentation.

Carcasses were thawed and RNA extracted from livers; 3) To understand how tissue preservation protocols affect gene expression mice were euthanized with euthasol and livers dissected and processed immediately or preserved by flash freezing in liquid nitrogen slow freezing on dry ice or immersion in RNAlater. Liver samples that were processed immediately were homogenized in RLT buffer and then either immediately further processed for RNA extraction or were stored for 70 days at -80C post-homogenization in sample RLT buffer prior to RNA extraction.