Re: Miroslav Hill responds

From: Dace (edace@earthlink.net)
Date: Wed 07 Dec 2005 - 21:18:09 GMT

  • Next message: Derek Gatherer: "Re: Miroslav Hill responds"

    Derek,

    > >What Hill has demonstrated is that when a colony of cells is subjected to
    a
    > >toxin and develops resistance to this toxin (over the course of
    > >generations), the same mutation enabling this resistance will also begin
    > >appearing in a closely related but physically separated culture. This
    > >indicates a nonrandom pattern of mutations in direct contradiction to
    > >neo-Darwinian orthodoxy.
    >
    > No, what it demonstrates is that putting fresh cells into a flask which
    has
    > previously been used, does odd things to the cells, in this case
    increasing the
    > mutation rate. What Hill compares is:
    >
    > 1) Cells from the parent stock, seeded into clean flasks. 2) Cells from
    the
    > parent stock, seeded into serial culture (the same flask into which the
    previous
    > seeding went)

    Here's Dr. Hill's latest response:

    >>>
    Dr. Gatherer confused the preliminary with decisive experiments. In a preliminary experiment (named serial assay), the tested cells were seeded on the top of depleted monolayer while in all subsequent, decisive experiments
    (redesigned serial assays) they were seeded into clean flasks. This has been said on the bottom of page 213 "....and seeded into separate flasks
    (instead of a depleted monolayer) containing the selection medium."
    >>>

    I'm afraid I haven't been of much help here, as I was also confused on this point. The decisive experiments, the ones on which the results are based, did not involve any reseeding of depleted monolayers. Hill redesigned the serial assay so as to avoid this step. All seeding was done into clean flasks.

    Also, keep in mind that the pattern of nonrandom mutations occurs in the physically separated culture never exposed to the toxin against which the mutation is beneficial. There's no odd pattern of mutations in the exposed culture but precisely the pattern that would be expected.

    ted

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