blue colonies-no Xgal

[Michael H. Bracey]

I recently cloned some PCR products into InVitrogen's tailed vector and 
transformed the ligation products into their SureShot Top10 cells which 
are supposed to have a lacIq repressor.  In the *absence* of both IPTG 
and X-gal, I got back about 50% blue colonies.  Is there a trivial 
explanation for this that I'm overlooking?  Where is the blue coming 
from?

Emailed replies are especially welcome.


Thanks,
Michael
mbracey at unix1.sncc.lsu.edu