Ligation problems on agarose-isolated fragments

[Philippe Lefebvre]

We experienced and are stille xperiencing similar problems.  We think it is a 
conjonctipn of several factors like old phenol (more than 2 weeks), the quality of 
the BAP or CIAP you are using (you should frequently test it for DNA degradation), 
but the most important factor is the insert to vector ratio, and we've seen 
tremendous differences in ligation efficiency upon varying the ratio from 0.1 to 10. 
 We do not know why, but it may help to tezst these parameters