March 8, 1960

Dr. Joshua Lederberg
Department of Genetics
Medical School
Stanford University
Palo Alto, California

Dear Joshua and Esther:

f hope ali has been well with you and that you have a pleasant journey
to England next month. Alec Bernstein has been urging me to try and come
as the Symposium looks good, but I cannot for lack of funds and time. It
should be an interesting session,

T have a problem, We have been making more mutants for macping pur-
poses, etc., and at the moment have for these mutants some unwieldy numbers,
Could it be possible to get a batch of Gal numbers assigned to us, to avoid
the above p-oblem and also to avoid confusing the literature? Stock cultures
are becoming a problem with us, as our reference by page numbers are now
intruding into the lower W- numbers,

The second problem has to do with information on W3142 and W2312, I
believe these are deletion mutants, I have no record of obtaining rever-
sions and recent experiments to obtain them, even employing UV have been
unsuccessful. Reconstruction experiments on minimal Gal show that one is
able to recover added Gal” to 100% recovery so that it is not likely to be
a case of supression of the reversions by the Gal” background. These mut-
ants you will recall are not transformed to Gai* by any HFT lysate. | I think
that what this means is al although Gal* is dominant to Gal » Gal ig not
dominant to a deficiency. I have some experiments (Gal /Gal ——vomemmeeet >
HFT Gal*) in progress and will advise you of the results shot £5,

we have had no success at obtaining HFT 3 or HFT 9 even employing
W4654 as an indicator, I am suspicious of these mutants and perhaps the
double mutant hypothesis (one mutation a lethal?) is really correct. We
have several other HFT'S for our other mutants,

I expect within a couple of weeks to be able to classify, at least
partially, our mutants for the biochemical steps involved. Kinase-less
mutants should not be hard to identify in the group.
anon

The mapping goes not too badly and a late estimate I enclose below.
We have no cases of transductions of 4 -—=«x 3 yielding position effect
heterogenotes, with approximately 300 transductions streaked out. This
may be another exceptional case. Incidently, I talked with Benzer last week
at Purdue and he now has nutants that resemble the 4, 7 interaction. Said
he found them as scon as he looked for them,

Weather was very bad the last two weeks here, but I was away and didn't
mind it. Helvise and Margaret had to put up with the below zero weather.
Today is back to normal, a beautiful, bright, clear, warm day,

Best wishes,

MLH 32 bm