DNA isolation

Zampicinini Giampaolo jpz at ipsnet.it
Tue Apr 8 10:27:42 EST 1997


>I extract DNA from vegetable plant for RAPD analysis. This is done with
>standaard CTAB extraction. The disruption of the plant material is done
>by a powerdrill in a eppendorf tube. Does anybody outthere in cyberspace
>know a method to disrupt 96 plant samples at once or has some good
>ideas.

>Greetings,

>Stefan van Lier
>Technical assistent Molecular Biology.



I think some kind of multi tube grinder/homogenizer could be made
more or less this way. The following items are needed:
-1 spare vortex machine or similar orbital shaker.
-2 identical eppendorf racks (x 96 tubes, I guess);
 they should hold the tubes fairly tightly.

Basically, the idea is to use one of the racks to hold the tubes,
while pestels are fixed to each well of the other rack; the rack with
the sample tubes  should be solidly fixed to the the shaker;
then, holding firmly the rack with the pestels, (adding to it some
kind of handle would help) the pestels are dipped in the tubes and
the shaker is started in order to homogenize the 96 samples at once.
However, with this method the pestels ar not actually rotating, and
the mechanical action may not be enough to disrupt the samples'
tissue; but it could be enough if the tissue is soft.
Making from scratch a machine with 96 rotating heads would be far too
complicated , it needs to be made to order by some outside firm and
would likely be expensive.  I think the best material for the pestels
would be polyethylene, which is easy to work even with the tools of
the average lab and can be glued simply by melting it with a flame;
an idea would be to use as pestels the polyethylene sticks that are
used by the kind of hot glue "guns" that work by melting the plastic
into a glue and can be found at most harware stores in a variety of
sizes; moreover, polyethylene is quite flexible, thus allowing for
the orbital radius of the shaker, and will produce a whipping action
that is likely to help homogenization.  Anyway, if you do this work
on a regular basis, the time wasted with this hardware fiddling could
be worth the effort.




                        I  <--- Handle
                        I
                        I
             ___________I___________   <--- Pestel rack
             I I I I I I I I I I I I


             U U U U U U U U U U U U
             -----------------------
             I                     I   <--- Eppendorf rack
             -----------------------
            __________TTT____________   
           [                         ]
           [ orbital shaker          ]
           [                         ]
           [                         ]
           [_________________________]




Greetings & happy grinding...

Giampaolo Zampicinini
graduating student
Universita' di Torino, dipartimento di Biologia Animale.






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