KAROLINSKA INSTITUTET

STOCKHOLM 60, SYVE DEN

 

January, 25th, 1960.

DEPARTMENT OF BACTERIOLOGY

-rofessor Joshua Lederberg
Dept. of Genetics

Stanford

Palo Altro, Calif.

USA

Dear Prof. Ledcorberg,

About a year ago I became interested in the cultivatio!? S¥ microor-
ganisms under high rressure and several sidelines soon devsloned. One
concerned the effects of very high oressures on vhage-infected E.coli B.
The controls, where uninfected cells were*exposed, unexpectedly yielded
plaques, so we had to assume that induction of some proph:ge had taken
place. From the morphological point of viée the "new phage" resembles
T5 but it seems to differ from this virus in certain respects (burst size
etc.).

One of our present problems is that we don’t know anything about the
prevalence of the phage in other B lines. Our particular strain has
been used in this laboratory for more than ten years, and it would be in-
teresting to know, if the phage we induce is also found in the B-strains
from other laboratories. Could you possibly send us the regular B-line
which is used in your laboratory plus any mutants which you think we should
check for this peculiar kind of lysogenicity. I enclose a copy of a manu-
script which has been sent in for vyubhlication.

Recalling with sreat pleasure our contacts in the past, 1 remain

Youxs sincerely

Ge

é
Crees a;
C.-G.Hedén

Asso.vrof.M.D.

P,S.Letters similar to his one are also sent to Drs. Cohen, Delbriick,
Hershey, Luria and Spiegelman.