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FEDERAL, SECURITY AGENCY
PUBLIC HEALTH SERVICE

IN REPLYING, ADDRESS THE

Tuberculosis Research Laboratory,
411 East 69th St., New York 21, N. Y.

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September 28, 1951,

Dr. Joshua Lederberg,
Department of Genetics,

The University of Wisconsin,
College of Agriculture,
Madison 6, Wisconsin.

Dear Joshua:

The replica plating method has been working beautifully.
I am not sure it will be too useful, however, for isolating a POB
mutantsince this factor is heavily excreted by wild type. Reconstruc-
tion experiments on a mixture of wild type with a mutant requiring
PABA, which is also excreted hy wild type, showed that even at fairly
low population densities (50-100 colonies per plate) the mutants grew
on minimal as well as supplemented medium. They could be distinguished
from wild type only by their smaller colony size at fairly early stages
in cultivation. Since the lag period immediately after exposure to
penicillin is highly variable, many mutant colonies appearing in our
experience only after three days, it might be necessary to introduce
intermediate cultivation between a penicillin exposure and replica
plating.

I enjoyed reading your manuscript on this subject which
Werner borrowed from Aaron. I recall that you had quite a complete
bibliography on the evidence for spontaneous mutation to drug resistance,
and wonder whether you got hold of the following reference, which I ran
into last night: Yegian, Budd, and Vanderlinde, J. Bact. 58, 257 (1949).

We have a few results on the strains vou sent. W1504 was a
mixture of tyrosine and proline auxotrophs (I hope this disclosure won't
discourage you from sending more\). PF=4 was a prototroph from which we
couldn't recover any tryptophan auxotrophs, PF-11 requires a rather high
concentration of Yeast Extract and does not respond to mixtures of any
of the factors we have on hand; this would be nice to look into, but
doesn't fit our plans at the moment. PF=21, in addition to its leucine
requirement, responds to a mixture of arginine and a pyrimidine. This
double requirement has been previously encountered by Rnepke as quoted
by Tatum in the Cold Snoring Harbor Symposium, and we have also picked
it up before. I am very grateful for it as I have been planning , with
our strain, to look into the possibility that Philip Cohen's citrulline

 
Dr. Joshua Lederberg September 28, 1951.

precursor might be a growth factor for this strain. PF=3, phenylalanine
auxotroph of Pseudomonas, is particularly interesting since it resembles
our coli mutants in this group, and the Salmonella ones you sent, in
responding to phenylpyruvic acid as well as phenylalanine , but it differs
in not excreting any tyrosine.

Thanks for the information about dried silica jelt. Ne nearly
lost a couple of valuable strains over the summer and will certainly
try this technique.

I gather you didn't care much for the papers of Zeller and
Yegian in recent issues of the Journal of Bacteriology. I haven't got
around to reading the first, but I don't have any strong reaction to
the second. The facts reported in it are of great interest to me and
I am delighted to be able to include them in the manuscript I have been
preparing on the PNBA=sulfonamide story. Yegian's interpretation seems
to me naive in that he doesn't consider any possibility other than the
action of the two drugs on different enzymes, - but for a man who has
been working on tubercle bacilli in a sanitorium fcr 20 years I hardly
would expect anything better; in fact, considering his background I was
really quite favorably impressed by his general analysis of the problem
of drug resistance in tubercle bacilli in the American Review of Tuber-
culosis: Yegian, D., and R. J. Vanderlinde, Am. Rev, Tuberc. 61, 483
(1950). As I got the story from Gardiner Middlebrook, Yegian went to a
tuberculosis sanitorium without any scientific training and is literally
a self-made man in this field. I trust you will forgive me for this
temporary excess of charityt

Sincerely yours,

ca

(- we Tt
Bernard D, Davis

BDD/h1

P.S. = Results on growth requirements of your multiple aromatics have

just ccme through; we are planring to look into their accumulations next.

In general, I would say you have under-estimated their requirements for
rapid grcwth, We verify your labelling of W-1426 as a triple (Ty- V-trypt)»

We find that SW-38 is, a HAR sg rather than double, W1427 a mixture of
triple and quadruple, ‘tatcher: ep tyrosine or tryptophan, W-1104 and

We1150 are quadruple rather than triple, You may not have picked up

their PAB requirement unless your glassware, etc., is very clean, since

the amount required is very small,

BeD.De