Home made DH5alpha chemically comp. cells - (May/08/2008 )

Hi everyone
I just made my own DH5alpha chemically comp cells but they are acting funny----I'm getting transformants but the colonies are very small and seem to be growing very slowly (maybe 4-6 hours more than my old cells that I made)----is there a way to confirm that they are actually DH5alpha or should I just dump them and re-make them?
thanks for your help
Lisa

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I don't really remember abour the DH5 alpha but some cells are growing slowly than other I wouldn't be too worry as long as they don't cause any trouble. Maybe you change the quality of media ? (did you check them on an antibiotic LB plate to be sure ?)

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thanks-----I am growing on Amp plates and I know my antibiotic is OK----I was just worried that maybe I had some other strain of Ecoli when I grew up my original Dh5alpha and made this unknown strain comp too but then again if that happened I would see two different growth patterns on my plate

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I use regularly the Top 10f' from Invitrogen and they also grow as very tiny colonies so I don't think it's a real concern

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Hmmm, sounds like the growth characteristics of your cells have changed. We usually make our own competent cells from one of the original vials from the company so that each time we know the cells are going to be pretty close to what they should be. Cells can lose their characteristics over time. Have you changed vectors recently? Low copy vectors will give you smaller colonies. Recovering the cells following transformation improves colony size. You could make a new batch and see if the same thing happens, maybe they weren't growing well in this batch. Or, as Jipes said, if they're still producing what you want then you can also just continue using them.

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thanks for your help

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