No replies to this topic

[jn315]

I have been having issues with the vehicle controls in my NRU assays.  They must have an OD540 of >0.3.  Lately, the readings are between 0.20 and 0.27.  I have been using the Fisher NR (cat # N129-25).  I ordered some from Sigma (cat # N4638) and tried that.  With the Sigma NR, my readings were even lower.  The cells look fine, before adding NR, they are ~90% confluent, morphologically normal and there are still some mitotic cells present.

When I dilute the NR for use, it is in basal DMEM (no serum, antibiotics, L-glutamine) and incubated overnight at 37C.  Just before use, I filter it using a Millipore 0.2 micron filter.  Also, my media does not contain phenol red.

Does anyone have any helpful hints?  My Fisher NR is about 3 years old and has been stored appropriately.

Thanks!