Size of 23s and 16s RNA different - (Apr/24/2006 ) I did DNA
extraction from B. subtilis sample, but did not use any RNase to
remove RNA in my sample. Two distinct bands appear at size 1.2kb
and 1.7kb. I am suspecting they are 16s and 23s rRNA. However, I
found out the size of 23 and 16s respectively are 2.9kb and
1.5kb. Does electrophoresis conditions will affect the size of
the RNA? I run normal agarose gel by the way, under non-
denaturing conditions. Any other factors will affect the size of
the RNA from different bacteria? I'm not very familiar with this
topic, but I remember two possibilites: It is the RNA you
mention, but already fragmented. Or second, the RNA is somewhat
folded, i.e. having a secondary structure and so appearing to be
smaller as expected on the gel. But this are only guesses. sizes
of rRNAs will depend on percentage of gel, whether you use TBE
or TAE.....try a RNase digest to see if you remove them if it is
a problem.....? You can't accurately size RNA under non-
denaturing conditions.