UNIVERSITY of WASHINGTON
SCHOOL OF MEDICINE
DEPARTMENT OF MICROBIOLOGY
SEATTLE $

May 25, 1954

Dr. Joshua Lederberg
Department of Genetics

The University of Wisconsin
Madison 6, Wisconsin

Dear Dr, Lederberg:

Thank you for your reading of the manuscript and for the suggestions.
I have revised the paper on the basis of your suggestions and those of the
editorial staff of the Journal of Bacteriology. On the question of terminol-
ogy I prefer for the present to retain the term conversion for the diphtheria
phenomenon, Until the fundamental relationship of these diverse gers tic
phenomena become clarified I feel there is some merit in underlining their
differences.

In some recent work evidence has appeared which indicates tht the ability
of phage beta to toxigenize is a characteristica capable of segregating in an
independent fashion from other traits eg host range. Strain C4 lysogenized
with the non-toxigenizing phage is still sensitive to beta phage. Organisms
carrying what appear to be recombinant phages can be isolated from resistant
growth following beta lysis. Some strains are non—-toxigenic yet carry a phage
identical to beta in other characteristics. On the other hand some are toxi-
genic yet the phage being carried reflects for example the host range of
the original non-toxigenizing phage, It is this phase of the work that we
are currently werking on. Unfortunately teaching duties and loss of my tech-
nician through marriage have slowed up the effort,

While the above work pin points the critical site of activity in the
prophage to an even smaller unit I am in agreement with your observation that
we are still no closer to the basic mechanism of conversion, I am of the
opinion that for the present there is no way of frontally attacking the prob-
lem which resolves itself to one of nuclear-cytoplasmic interactions, Never-
theless the relationship of phage genetic material to that of the host is
an intriguing problem in itself.

Again my thanks for your time and I hope to continue this correspondence
with somewhat greater regularity than in the past.

Sincerely yours,

lan PGi

1B. Groman