Dear Carl,

The only axenic strain with which I am acquainted is Ax-2. In its case,
one gets reproducible doubling times ~8hr when one tests sub-clones of an
originally stored clone. On the other hand, if one works with spores or
amoebae that are the products of many life cycles, the doubling time can
show a substantial increase relative to what it was in the initial
generation; in my experience, it never decreases. The problem does not
seem to occur with genuine (non-axenic) wild-type strains of D.
dictyostelium that are cultured on bacteria.

Best wishes,

Vidya

> Dear Dicty Community, I'm much obliged for an opinion as to whether our
> lab
> has gotten into trouble in our suspension culture of AX4. My concern is
> that we are now getting doubling times (measured at around 5x10^5
> cells/ml)
> of 14 to 15 hours whereas a year ago, it was typically 8 to 9 hours. We
> use
> Formedium HL5 with glucose and grow at 20-21 C temperature. I'm hoping
> that
> anyone with experience could say if this seems reasonable, or whether we
> should take it as a sign that we need to check more elements of our
> technique (we are using a fresh strain from the Stock Center, and replaced
> our pH meter). We can work with this doubling time, but I'm concerned that
> we won't be doing good science.  Thanks for reading (and thanks to the
> community for years of very helpful advice)!, Carl
>
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