> Hello everybody, I have questions to ask for your help.
> I have used GeneClean to recover DNA from agarose. After eluting the DNA
> in TE, I discover quite serious DNA degradation from gel electrophoresis.
> I suspect the sources of contamination: TE or GlassMilk or both. In order
> to eliminate the problem, I autoclave the TE and the question is, is it
> possible to autoclave the GlassMilk without affect the DNA-binding
I think the glassmilk can be quite autoclaved.
> The second question is what density of the E.coli (OD600) suitable
> to make competent cells?
Usually OD600 must be about 0.5.
> Is it necessary that the higher OD (e.g. 6.0), the lower transformation
> efficiency as a result?
Yes, of course.