I've got a problem.
I constructed a cosmid library of a streptomyces species. The cosmid that
I used was Supercos suplied by Stratagene. After having constructed the
library I used the same to screen for a gene with a homologous probe by
colony hybridization. I got three clones. I picked these clones from the
glycerol stocks and cultuerd them. I extracted cosmid from these cultures,
digested them with AseI to release the incert. To my surprise there was no
incert. Next, I did a slot blot before digesting with AseI. There was no
In short, my problem is this, - when I do a colony blot, I get a
signal on colony hybridization, but when I do a slot blot I do not get a
signal. This I have repeated with a totally different probe and screened
the same library. This time too I got a clone, but on further analyses,
ie, slot blot and AseI digestion, the results turn out to be negative.
Can somebody help me with this please.
Thanks in advance.