Pustic HEALTH LABORATORY SERVICE
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CENTRAL PUBLIC HEALTH LABORATORY
COLINDALE AVENUE
LONDON, N.W.9

Telephone: COLINDALE 6041-4081
Telegrams: DEFENDER, HYDE, LONDON

 

25 th May, 1952 °

Dear Professor Lederberg,

I am sorry to have been so long replying to your letter of
April 18th but I delayed purposely expecting some news from Geneva about
the confirmation of my Fellowship. However nothing has yet arrived so
I had better delayno longer; though until it does I cannot make any
definite plans about dates.

In answer to your questions, I anticipated staying in the States
about 6 months of which I should like to spend 4 months with you and the
remaining two months travelling round and visiting other labs. Of course
I could always cut out the travelling part if anything important cropped
up on the research side,

It would interest me very much to try and find other recombination
systems in the Salmonellas and would also fit in with the work of my
department. Your suggestion about S.Thompson seems a very good one to
me and I have already started work on collecting strains of the organism;
amongst these are three which are lysogenic for S.Dublin and perhaps it
would be a good idea to try these first in making crosses between Salmonella
groups C and D. All the Dublin strains I have collected so far are atixo~
trophs. I have not yet had time to identify the deficiency but judging
from your paper in the Arch. B iochem., it is likely, to be for thiamime.

I have good contacts with Williams Smith and can almost certainly get hold
of a set of typing phages for S. Thompson.

As regards the S, Potsdam x typhi-muriun cross I have not yet got
around to synthepsiMg nutritional mutants and would gratefully accept
your offer of some auxotrophic typhi-murium strains, The conditions
existing in our lab, are not very favourable to the kind of work involved.
I am fairly certain that some kind of exchange takes place and that the
two organisms are not mutually lysogentc but have no clue whatsoever as to
the mechanism involved,

(1)
(2).

Prof, Lederberg, cont., 25th, May 1952

If you have no particular problem in mind I think it would
problably be best for me to try the Thompson crosses before returning to
Potsdam work, and to concentrate on the former, if I get any results with
it. I will keep:you informed as to how it goes, Incidentgy I have just
got what may be very useful as a marker, namely a Cobalt resistant strain
of typhi which was discovered accidentally by Dr. H.S Anderson here,

Yours sincerely,

COS ices

Professor J, Lederberg,
Dept. of Genetics,
University of Wisconsin,
Madison, 6

Wisconsin,

U.S.A.