I am trying to screen my transformant yeast which contain
YEp-based shuttle vector by URA-3 auxotroph test.From the test I have got
the positive clones but when I check their plasmids,by glass bead
extraction and transform back into E.coli, I can't found them. Can anyone
explain to me why not have E.coli transformant when the auxotroph
screening is positive? And where can I get the detail of this case?