DNA unmasked in the red rain cells of Kerala.

Extraordinary claims have been made for the biological properties of the red rain cells of Kerala, including a suggestion that they lack DNA. We have investigated the fluorescence properties of red rain cells, and the solubility of the red pigment in a variety of solvents. Extraction of the pigment with DMSO allowed successful demonstration of DNA using DAPI staining. Cellular impermeability to staining reagents due to the red pigment is the likely explanation for the failure of previous efforts to demonstrate DNA in red rain cells.