January 20, 1960

Professor Joshua Lederberg
Department of Genetics
Sehool of Medicine
Stanford University

Palo Alto, California

Dear Joshua and Esther:

I have finally gotten into my new laboratory facilities and can settle
down to work in greater earnest, although we have been limping along during
the construction. I'll append our latest "map" which has been strengthened
by additional experiments and represents the pooling of data requested by
Armitage.

With regard to position effect heterogenctes, we have obtained the
following since last I wrote:

1) 2° «=x 3°
2) 17) wax 3°
3) 6° x 3°
(kh) 17 sx 9
(5) rv -ex 97
‘*} 27 nex 9
7 6" <x 9
(8) 7 w=x 9

This confirms Esther's previous isolation of these genotypes. However, in
the case of 6° --xX 3°, one of 3) transductions resulted in a PE heterogenote,
the others were all gal*, and some of the others are similar to this. I
don't know what the chances are of missing a PE colony when one streaks out
the partially gal* colony representing the transduction initially, but the
studies of 1, i 6, 7, that I have made previously gave results such as

20 of 20 \” -=x 1” yielded PE colonies in the first streaks. Gal |, ~-x Gal7,
and the reciprocal are characterized by the fact that none of some 200
transductions showed PE colonies in the first streak and I have had Gal*
heterogenotes containing both Galy and Gal?. As I have not as yet obtained
Gal3 and Galo HFT's, I have not béen able to check to see if the Gal*
transductants obtained in the various instances, contain both exo- and
endogenotic Gal”. This has also restricted my three point tests, but will
eventually overcome.
(2)

What I believe must be explained is why go some transductions yield
Gal* clones rather than PE more frequently than others.

With regard to our proposed trip to California, Margaret's spring
vacation is the week of April 10th, which is most inconvenient. Perhaps
you should advise of a week in later April or May when you will be there
and we can make arrangements for Margaret to get her school work in advance.
She has been looking forward to "our California trip" and is eager to go.

As T plan to give a paper at the SAB meeting May 1 - 5, I will be able only
to use part of that week for a Stanford trip, which part depending upon
when my paper is scheduled. Earlier than this, I must go to Philadelphia
Feb. 2-263 Purdue Feb. 28-Mar. 13 and New York Mar. 2=l3 so these dates
are out,

I heard recently that Alec Bernstein will most likely take the position
at Tulane that was offered him and plans to visit in New Orleans to see the
place the first week in February. I tried to get him to visit here also
but neither he nor I have the travel funds.

I have a problem on which I have been sitting for a month or so.
Bob Wright wrote me of a Barney Egan, whom he thought might want to come
to the U.S.A, for a Ph.D. after his M.S. in March, 1960. Ye looks like
a good prospect (I have his grades, etc) but I don't really believe I would
be doing him a service by taking him on here as a graduate student. Have
you heard of him or would you be interested in him? I believe he is
associated with Holloway at the moment.

Sincerely,

MLM slbm