# of Recombinants Needed for Cloning

AL R. PLUMMER aplummer at sprint.uccs.edu
Fri Aug 4 15:46:10 EST 1995


I have a rather simple question.  I need to know what the minimum # of 
transformed colonies people have used to clone their genes of interest.
I know the figure of 100,000 (Guide to Yeast Genetics and Molecular 
Biology) is often used, but can anyone give me the rational behind this
(reference)?  I also know of the formula for determining the number of 
clones required (N) to isolate a gene with a certain probability (P),
but when I use this formula to calculate (N) with a (P=0.95) for a 
library containing 10-15 kb inserts I come with something around only
5,000 clones.  Finally, I have read a paper by Jasper Rine, where he
he describes targeted selection of recombinant clones through gene 
dosage effects.  In this paper he describes the cloning of a Tunicamycin
resistance gene with a multi-copy library with only 4,000 transformants.
                                                    ^^^^^               
I would appreciate answers for both CEN and 2-micron based plasmids.

Thanks for any answers or ideas,

		-AL(aplummer at sprint.uccs.edu)   



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