December 22, 1954

Dr. M. Demerec

Department of Genetics
Carnegie Institution

Cold Spring Harbor, L.I., N.Y.

Dear Dr. Demerec:

In order to complete our studies on the genetic determination of
flagellar antigens in Salmonella, I am anxious to look for auxotrophic
markers that night bealinked to the H, and H. loci. The chanesas of fin-
ding any are, of course, very low, but it wottld be worth some effort,

It would be extremely helpful and advantageous to us If we could
benefit from the work you and your assistants have already done in iso-
lating and screening sc many auxotrophs. As our interest lies exclusively
in this application, it would suffice for us to have each :mtant locus
that we might test represented merely by ita corresponding lysate. In
fact, 1f it were convenient for you, we could do very well with a mixture
of lysates of diverse mtants, aince our screening method (bebed on selec-
tion of H, transductions, and tests for correlated auxotrophics) would auto-
matically pick out what we wanted. In preparing such mixtures, it would
be wisest to use approximately equal aliquots for each component, and to
record what went in for later recosd.

I would be auch obliged to you if you can comply with this request.
The program will be under the immediate supervision of a naw student from
Japan (Tetsuo Iino}. He 1s not due to arrive until February 1, but I would
be pleased if the reagents were at hand at that time.

Unless we are ummally lucky, we will be spending some time at making
more mitants ourselves, and will be happy to exchange anything we run into
that would be of particular interest to your program.

With best wishes for the season,

Yours sincerely,

Joshua Lederberg
Professor of Genetics