We were one of the labs that suggested vitamin supplements to counter precisely this problem.  Cells would grow at different speeds depending on background and in particular density (cells grew better above a threshold density in the region of 10^6/ml).  The vitamins (and also not autoclaving the sugar; we made a 20x supplement with both) made the problem completely go away.  They also slightly improved the doubling time.  They do, however, inhibit development somewhat.

Of course, that doesn't mean it'll answer your problem.  Also, we moved labs and now it isn't apparently necessary - we haven't had a recurrence, and don't use the vitamins any more.

Have you raised the issue with formedium?  They would want to know.  But our formedium HL5 seems fine.

	Robert

On 21 Jul 2010, at 15:43, Christian Hammann wrote:

> Is this also observed in other labs?
> What is the usual doubling time of AX2 in your hands?
> How constant is that doubling time?
> How many of you have tried to supplement the medium with vitamins, as stated in the technical comments on Dictybase, and how successful was that?

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Professor Robert Insall
CR-UK Beatson Institute for Cancer Research
Switchback Road, Bearsden
Glasgow G61 1BD, UK

Tel.  (0/44) 141 330 4005
Web http://www.beatson.gla.ac.uk/robert_insall
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