TOQONOOGOOOOOX
peseveccesccoens
Department of Medical Genetics

April 29, 1957

Dear Larry: ON pa |

It's heen a couple of weeks since we returned now, but Ive had too
much to do to write sooner. Esther and I were pleased to get your sum
maries, just before we left, ani hope these are soon to be followed by
the op. magn. Esther would like to keep in touch with you about lambda
details; there 't much we can add that you don't know about. She's
been crossing Lp” Gal,” x Lp* Gal,~ and scoring the Gal” for Lp h/+, hoping
to get a map, but there aren't enough done yet to get any definite conclusions.
Also, we've been waiting in vain for an enzymatic diagnosis of Gal...
I am enclosing a summary, which of course leans heavily on older findings,
‘ which was part of an annual report I sent in a while ago. A fey experiment
we still want to do is tranaduction from a heterogemote by Pl or other phages,
but there are all kinds of s&lly snags. At present we have the ‘contradiction!
that the lambda from a heterogenote carries only one piece (which was recon~
firmed byt

+ ex/ 2 —x 47 ==s + ex/4” and no + ex/ 27
while in crossing, as you know, the opposite result is more frequent.

L-
In protoplasts, we have confirmed that 'satable/forms' arising during

the propagation of Y-10 in penicillin-sucrose agar include some DAP-auxotrophs;
we are still looking for other types. a'’ve still had no locking in dna-tranad.
with protoplastic recipients, but I am planning a strong push on this whole
problem for the next year. The last few weeks, we screened a couple pf hundred
different coli strains as potential reciplenta:

s¥ bac | S88 g® Lact --a, 8? Lac”
This was based on the plausible idea that only a rare strain would work; the
only thing we picked up was a ftmum false alarm or two and one coli straing

that seems to be exceptionally mitable for a series of markers, so you can
imagine the trouble it gave.

Alsca enclosed is a olipping that I imagine Roger will be interested
to see. (Our mailing address is just the same, but we're drawing plans for
about 5000 ft” of space for the department in a new research wing at the
Medical School (at the corner of Charter St. and Linden Drive); this won't
be ready for perhaps 2 years.) We are hot on the trail of our third member;
you probably know whom we have in mind. We have closed out our negotiations
with Stanford; and Harvard; Berkeley is still on a very alow fire, but it will
be julte some time before there's any chance of its coming to be boil.

Best. wishes,