THE UNIVERSITY OF WISCONSIN
COLLEGE OF AGRICULTURE

Madison 6

DEPARTMENT OF GENETICS

May 5, 1953

Professor &. L. Tatum
Department of Biology
Stanford University
California

Deaé Ed:

I'm sorry we did not get to see you during your visit, but perhaps it's

just as well, since Esther and I were both half-expired with colds at the
time.

You must be as annoyed as I am about the inexcusable delays in the AAAS
publication. I am glad that you comcur in not wanting to revise: we could do
that sort of thing indefinitely. If I may confess one additional slight dis-
pleasuge, to which I may or may not be entitled, it is that you presented me
with a fait accompli on the reversal of authorship. I can underatand well enough
why you should exercise this prerogative, and will acquiesce in it, but would
have appreciated the opportunity to try to dissuade you from it. Let it stand,
but if you should change your mind during the next few years while this thing
is in press, I will hasten to insist on the restoration of the original order.

There are two scientific matters about which I wanted to ask for some infor—
mation. The first is 58-161 (perhaps we've gone over this before): do you have
any cultures of 58-161 or proximate derivative of it, for which there is any
hope of the retention of the biotin requirement? Everything I have is definitely
B+ (with 58 biobin-dependent as control), and Phyllis Fried was unable to so much.
as repeat the isolation of B- recombinants per table 4 of the 1947 Genetics
paper. I cannot find, in noted of experiments at Yale, explicit tests of the
nutrition of 58-161, except that it was noted that platings on methionine agar
were quite turbad, so that Be could not be used as a selective marfer. The most
recent experiment in which B~ recombinants were deéterted was 3/9/47..1 assumed
all along that either agar or methionine was furhishing or sparing biotin. -Wirthe
this—is—doubtkess—trus—to some extent, While these are both true, to som extent,
they do not explain the fact, meanwhile concealed, that "58-161" has lost its
biotin requirement. Would it be too much to ask what specific nutritional tests
you may have made on the biotin-requirement of 58-161 since its isolation? To
avoid further confusion, we intend to describe our present culture, B+M- as W6,
an inadvertent, spontaneous reversion of 58-161, B-M- (possibly no longer availabl

The aecond matter concerns a paper that Cavalli & I have been writing on the
genetics of resistance, for the Rome Congress, (We probably will not be there in
person, and CavhAli will read it). I do not know if there would still be time to
dnelude this reference, but I recall your once remarking on a brief study of resis
tance to valine or acetyl-valine. Has this ever been written up in any form? As
I remember there were some possibilities in these as markers. Any details you
could furnish, either for reference or for my own curiosity would be appreciated.

bu gore yey C he Cogn ? Spacoreiy,
ZS. Yete« awthootig Ya + Hail lL Ly soy eneat I

i E ML. ond SL. th Phe rece [hes can

Pitted wnt poor Ugehn wet hell whew boar Ue
(s° OW