High altitude robotic yeast culture sampling - (Jun/25/2007 )

Hello,
I am in the process of building a yeast incubator that will robotically sample the cultures in a high altitude environment (near space). My problem is that directly after sampling I am interested in killing the yeast while maintaining RNA integrity for as long as 72 hours (T=30 degrees C). I'm looking for a reagent into which I can aliqote 3 ml of yeast culture that could accomplish this tasks. Any ideas?
Thanks

Trizol... which is a phenol/guanidine thiocyanate (with some extra bits) solution. This a commonly used solution to extract RNA. However I have no idea how long RNA will survive in said solution for prolong periods at elevated temperatures. You might need to do an experiment, ie incubating yeast cell in Trizol for 72hrs at 30 celsius.

If trizol is too pricy, you could make your own solution, along the same vein.

Liquid nitrogen is also good. Can't go wrong with that But you probably can't have a nice vat of liquid nitrogen.

In anycase, the main key to preserving RNA or DNA is to inhibit nucleases, which can be done by denaturing or inhibiting the protein's activity. (Thus the phenol and guanidine thiocyanate. EDTA to chelate Mg ions.. which are required for enzyme activity)

However RNA has an additional problems as it is labile in water. RNA gets hydrolysed more quickly then DNA. Can you spare any refridgeration for the cells?

Does anybody know how well does RNA take to incubating at 30 celsius for a prolong period?