Samples for RNA analysis

[martiny]

Dear colleagues,
I am planning on taking some seawater samples (oligotrophic open ocean) that I want to use for RNA expression analysis. In particular, I am interested in looking at gene expression of picocyanobacteria. To that end, I have a few questions that I am very interested in hearing your answers to.
What volume of seawater should I filter (I was thinking 1L)?
How would you store the samples? (I was thinking either as dry filters in liq. nitrogen or with RNAlater in liq. nitrogen)?

Any suggestions are very welcome.
Thanks,
Adam Martiny

[Heather Wright]

Adam
The Moore lab took samples for qPCR in the Southern Ocean. I believe 1L water was filtered through a double stacked GF/F and .2um (I can check that). The dry filter was then flash frozen in LN and stored in liquid until we dry shipped it back.  The samples are now in -80 freezer until processed.  If you are in oligotrophic waters you could filter a greater volume.  As I recall, the samples took a very long time to filter (partly from the doubling up of filters) and also because we were in productive waters.

Our reference was in consultation with Gabrielle Rocap from UW.

Best of luck,
Heather Anne