Molecular
biologists who were in graduate school in the 90’s learned how to
isolate plasmid DNA from E. coli cultures by a method called “boil-prep”
during their first lab rotation. This process involved mixing the
bacterial cell pellet in a little bit of detergent, salt and sucrose,
dabbed with some fresh lysozyme, and then you are ready to cook,
literally! Bacterial cell membranes are disrupted by boiling this soup
in a beaker of water over a Bunsen Burner for one minute, and the debris
(containing the broken cell membrane and attached chromosomal DNA) is
collected by centrifugation in a microfuge at top speed for 10 minutes.
Then comes the step that differentiates a true master of lab skills
versus a rotation student—if you knew just the right amount of bacterial
culture to begin with and handled the E coli pellet by the right
techniques, a skillful lab person could collect nearly all the liquid
without disturbing the pellet. Pouring out the plasmid-containing
supernatant without dislodging the goo on the side/bottom of the tube
was such a desirable skill that would not only give you your plasmid but
also give you admiration from fellow lab members. That is, of course,
if you were doing it before the mid-90’s, because after the introduction
of miniprep spin columns by Qiagen, nobody, even the true masters of
boil-preps (or its contemporary alkali prep that also involves pelleting
by centrifugation and careful removal of tiny volume of liquids
surrounding small pellets) would be showing off those skills any
longer.
It
is actually never easy or fun to collect liquid surrounding small
amount of beads or pellets as you always have to struggle to remove as
much liquid as possible while trying not to lose any of the beads
Some
of the old-timers used to also be very proud of being able to pour a
“sequencing gel” (a very thin ~40 cm x 30 cm polyacrylamide gel). I
still remember the first time I reported to the second rotation lab at
USC. After describing the lab research, the PI showed me around the lab
and complained how “Sarah destroyed all my sequencing gel plates”. But
consider this, in order to avoid any greasy spot on either plate, you
needed to wash both of them fanatically if not religiously. Why? You
would have just about a minute’s time to pour non-polymerized acrylamide
without leaking from the sides or bubbles forming anywhere in the DNA
running lanes, and then inserting a pair of paper-thin combs, all at a
speed quicker than TEMED/AP-catalyzed acrylamide polymerization. Good
thing that after capillary sequencing was invented, we all happily
retired our sequencing-gel pouring skills with a collective sigh of
relief.
Technology
will always move forward, so will the skills lab researchers will be
required to perfect. Using a spin column is very much a “skill-less”
technique in contrast to collecting pellets and washing beads after
centrifugation, but when there is a choice, people will chose the method
that requires “less skills”, such as the spin-column format as the
preferred platform for the new FP-nAb™ products.
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