Hi Vanessa,
Our best results happened when we started low (25) then ramped it up if cells were not dying up (50 was usually enough).  Then when colonies start standing out, go back to 25-35 and wait until they take over the dish.  You really have to look all the time.  This was for KOs only.  If possible, use another marker.
Jonathan

Dr. Jonathan Chubb
Division of Cell and Developmental Biology
School of Life Sciences
University of Dundee
Dow Street
Dundee
DD1 5EH
+44 (0) 1382 386336
>>> Vanessa Mcmains <[log in to unmask]> 02/27/09 8:03 PM >>>
Dicty community,

I am using hygromycin as a selectable marker for overexpression of a 
gene. I do not see high expression using 50ug/ul hygromycin for 
selection. What is the highest concentration that anyone has used in 
Dicty to successfully select for overexpressing cells using 
hygromycin?

Thanks,
Vanessa

The University of Dundee is a registered Scottish charity, No: SC015096