October 11, 1953

Dr. Seymour Pomper
Flééschmann Laboratorice
New York, Ne.

Dear 3y:

An Australian bacteriologist, Professor Rubbo, is due te visit Wisconsin
for a few months this winter. As he will be working primarily at the Enzyme
Inetitute, where Green and Lardy are deeply interéeted in mitochondrial
enzymology, and he has had a good deal of experience with the acridine dyes
(having been responsible for the development of "Euflavine’ as a topical
antiseptic), I thought he might well spend some time on the euflavine-"petite"
yeast problem. The routine might center on the effects of the acridine dyes
on isolated mitochondria, but I thought we ought to have a try at the artificial
reintroduction of wild type "mitochondria" into the petite cells.

Ne have not fully worked out the plana, but I thought to use some sort of
selective genetic approach, which brings me to the point of my letter. I om
writing to you in particular as almost the only yeast geneticiebtto have emphe-
sized the regular segregational benavior of your own straine! I hope we can
work on a system with no extra-Mendelian nonsense for the chromosomal markers.
Would you be able and willing to provide fertile, haploid cultures of the
following types:

prototrophic, and two distinct auxotrophs, preferably each in the two
mating types?

I would not be concerned about therequired growth factora for the mono-
ausotrophe, so long as they furnieh easily scored, unambiguous markere. Is
this too large an order?

Both for present and other purposes, do you know of any work (or did you do
any yourself at ORNL) on the mating capacity of haploid yeasts that have been
irradiated and made vegetatively inviable? One of. the problems will doubtless
be the introduction of the particles, and I though we might conceiagbly use the
mating procese for the purpose of venereal infection.

I don't think we will go very deeply into yeast genetics, the bacterial work
being more than we can handle. But this specific problem seemed like the most
appropriate for the immediate circumstances. I need not say that your help (and
any further co-nents you might have on the problem) would be deeply appreciated.

Yours sincerely,
Joshua Lederberg
PeSe Congratulatione on your escape

from Tennessee. I hope it ien't frying pan
into fire.