Help! Quantification of total RNA, equal loading
Wed Jun 7 12:43:40 EST 1995

In some cases using a "housekeeping" gene to normalise expression is not
appropriate - for example when comparing expression of a gene under
different stress conditions.  In some cases expression of housekeeping
genes may decline with various types of stress.  In these cases perhaps a
better control is a rRNA probe, if you are loading total RNA on your gels
rather than isolated mRNA.  However there are caveats with this type of
control probe as well, perhaps the stress (or whatever) may change the
ratio of mRNA:rRNA in your sample, or the total amount of RNA isolated
from a tissue may also be affected.  In short, it is important to realise
that there are limitations to using these sorts of controls.  Though I'm
not sure that there are any better alternatives out there yet.  Let us
know if there is!

Kim Snowden
ksnowden at

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