December 16, 1953

ATRMATL

Dr, FE. L, Tetam
Department of Biology
Stanford University
California

Dear Fd:

I hope this is not too soon to extend the very best wishes of the season and
for the New Year,

I am writing primarily to ask a favor that you may possibly be in a position
to extend, Dr. Sidney Rubbo from the University of Melbourne is visiting us for a
few months to do some work in microbial genetics. We thought it might be instructive
to start a few pilot expcriments with yeast. I had in mind primarily a comparison of
some features of the mating process in yeast with I. coli K12, especially possible
differential effects of ultraviolet light and other agents on vegetative and sexual
vitality. We would like to execute these experiments along lines rather similar to
the coli work and for this purpose would like to have on hand a set of a few different
matritional mutants belonging to one and the other of the mating types. Do you have
any of this sort of material on hand? If so, may I ask whether you can sem this to
us within a reasonably short time, as Dr, Rubbo's time here is rather limited. I
have gotten a few things from Sy Pomper but he has just moved to a new laboratory and
is pretty well engrossed in those matters. Whatever details may be available on the
pedicrees of these cultures would be appreciated, too.

Lately I have been s:ending (and I hope not wasting) a good deal of time on single-
cell isolations of crossing cultures of E. coli. ‘So far out of several score isolations
I have picked up two interesting ones. The first of these consisted of a pair -f cells,
om resembling each pare fen plated, gave rise to a large yield of recombinants as
well as the two parents. second instance was a rather large cell which gave rise
to recombinants and one of tie parents (the F-) after plating. These are, of course,
just preliminary results, although they tend to support the mating idea,

Yours as ever,

Joshua Lederberg

/mg