From: Derek Gatherer (d.gatherer@vir.gla.ac.uk)
Date: Fri 02 Dec 2005 - 11:16:21 GMT
Exactly, the selection medium simply gets living cells dumped in on
top of the dead ones. The same flask is used, not a clean one. In
the unselected medium there is passage (which means spinning down
cells, taking an aliquot and seeding it into a clean flask with fresh
medium). So tell me then, where's the control? What is being
compared with what?
At 20:46 30/11/2005, Dace wrote:
>Derek,> From: Derek Gatherer <d.gatherer@vir.gla.ac.uk>>> Before you
>start fulminating, Ted, I suggest you re-read Hill's>
>paper. (bottom of p212 and the first paragraph of 213). Then
>reread> his reply.I don't see the contradiction. In response to
>your question, Dr. Hill saidthat at each passage the culture was
>divided into two subpopulations whichwere both placed in clean
>flasks. Here's what he wrote in his paper:"Briefly, cells in the
>logarithmic phase of growth are, at each passage,divided into two
>unequal samples and subcultured by seeding the large sampleinto a
>selection medium and by growing the small one in a parallel
>culturewithout selection."No contradiction there. Perhaps you were
>thinking of what he wrote next:"The cell monolayer in the selection
>medium, when depleted, is periodicallyreplenished by the addition of
>fresh cells from the parallel culture."This is a separate issue,
>having nothing to do with splitting the culture ateach
>passage. Since the exposed culture is depleted by the toxin, it has
>tobe replenished with cells from the unexposed culture. Are you
>suggestingthat this somehow contaminated the unexposed culture? You
>have yet toexplain how Dr. Hill's results were compromised.ted> At
>21:26 27/11/2005, you wrote:> > > From: Derek Gatherer
><d.gatherer@vir.gla.ac.uk>> > >> > > Just ask him. I think you'll
>find the reply interesting.> >> >As I expected, Dr. Hill says the
>cultures went into clean flasks. I> >refrained from passing on your
>question because, frankly, it's insulting.> >Of course he used clean
>flasks! The man is a highly respected scientist.> >He's obviously
>not going to put his cultures into used flasks.Fortunately> >I
>didn't have to send him your question as he found it himself on the
>web> >and graciously passed on his answer to me. Here's his
>post:> >> >Dear Ted Dace,> >> >Incidentally, I have stumbled on the
>question by Dr. Gatherer who wrote:> >"What I'd like to ask Dr Hill
>is, when he splits the unexposed culture,do> >the cells to be
>exposed to the agent go into the same flask as
>theprevious> >exposure was carried out in? Or is the exposure
>culture set up in a clean> >flask each time?".> >> >The answer is as
>follows: At each passage, the cells are split into
>two> >subpopulations. One of them (a small one) goes into a clean
>flask with> >growth (nontoxic) medium and the other one (the large
>one) into a clean> >flask with toxic medium.> >> >Dr. Gatherer can
>send next questions directly to me on my
>address> >hill@infobiogen.fr. I am not used to forum discussions on
>the Internet> >though I read my email.> >> >Sincerely yours,> >Dr.
>Miroslav
>Hill> >==============================================================
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This was distributed via the memetics list associated with the
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For information about the journal and the list (e.g. unsubscribing)
see: http://www.cpm.mmu.ac.uk/jom-emit
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