RED RAIN: possible simple solution
Wed Dec 4 17:17:45 EST 1996
There has been a lot of concern over the reason, course and
solution for the infamous "RED RAIN" problem that has been appearing
,in ABI-377 gels. Following are my observations and possible simple
solution to eliminate the course. For those that do experience this
"RED RAIN" (and due to the course not everyone is going to be as
likely to observe the problem) please try this simple solution and let
me know, as well as others, whether this really is a solution.
Reason: I guess most people will have observed by know the the
reason for the "RED RAIN" is that bubbles get in front of the optics.
You can observe these bubbles by looking at you gel once it has
finished running (and you have "RED RAIN"). Remove the heater plate
and lift up the cross bar in front of the optics. These bubbles have
migrated (floated) from the bottom of the gel up. These bubbles are
between the gel and the glass plate as opposed to bubbles in the gel
itself. You can induce getting these bubbles i.e. make "RED RAIN"
(you can do this on a freshly used gel) by just lightly sticking a
spatula in at the bottom of your plate, jiggle it around, creating
bubbles in the plate then put it back in the ABI-377 and do plate
Course: The course for the above problem, i.e. the reason the
bubbles get there is due to drying of the gel as the gel is
polymerising. This courses the gel to wrinkle at the bottom. For
the polymerisation to give a good gel it has to have the correct media
(water) volume and stability (no evaporation) to work. As the gel is
polymerising and drying these wrinkles appear where bubbles can be
introduced and then these bubbles migrate up through these wrinkles.
I had gotten to the point where I had 100% success rate for predicting
which gels would produce "RED RAIN" (out of 15 gels run).
Solution: I have found that by putting a wet paper towel on the
bottom of the gel once it is poured, either on the Otter or as I do it
by tapping the solution down. This will keep the humidity up for the
gel and therefore will not have evaporation. Observing the gel that
is made this way you should observe that there is no wrinkling of the
gel at the bottom, and even after the gel has been run the bottom will
still be nice and even.
Well I hope this may help clear up some problems for all out
there. I am still using the wet towel method and haven't seen "RED
RAIN." Hopefully this was a simple solution and not just that it
happened to be good gels (hard to have good controls to totally test
this other than statistics and observation). Let us all know what you
Genome Therapeutics Corp.
100 Beaver St.
Waltham, MA 02154
tel: 617-893-5007 X2551
617-398-2551 (direct line)
toth at cric.com
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