Experienced, but OP50 problems . . .

Andrew Spencer aspencer at biochem.wisc.edu
Tue Dec 31 11:28:10 EST 2002


Hi All,

Recently I moved from a C. elegans lab to a lab that does a little C. 
elegans (two of us).  Since the move, my plates look strange with the 
OP50 appearing brittle.  That is, when you touch the surface with a 
pick, it tends to crack instead of being the normal soft and sort of 
creamy consistency I'm used to.  I don't think this is a 
contaminating strain of bacteria for the following reasons: 1. It 
looks and smells normal; and 2. I've tried streaking out fresh OP50 
from four different worm labs here and from a CGC plate I was sent 
harboring a worm strain and get the same problem. Plus, it's slow 
growing; doesn't take over the plate like most contaminating bacteria.

What is the problem here? The worms are happy (phenotypes are 
consistent, crosses work), but it's driving me nuts.

I assume the problem may be with my plates, so here is how I make them, FYI.

For 1 liter of NGM:

3 g NaCl
17 g Bacto-Agar (Becton, Dickinson)
2.5 g Bacto-Peptone (Difco)
Add 975 ml ddH20, autoclave

Add 1 ml 1M CaCl2; 1 ml 1M MgSO4; 12.5 ml 1M KPO4 buffer (made w/ 
monobasic and dibasic, pH 6.0)
(Sometimes I add 1 mg/ml uracil as per some recipes, but this doesn't 
corrolate with the OP50 problem.)

Add 1 ml 5 mg/ml cholesterol in EtOH.

That's it. Thanks for any ideas.

Andy



Andrew G. Spencer, Ph.D.
Department of Biochemistry
University of Wisconsin-Madison
ph: 608-262-0005 x3428
em: aspencer at biochem.wisc.edu

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