Par avion,.

INSTITUT SEROLOGIQUE DE L’ETAT
Service de Standardisation Biologique

Dans toute communication portant
sur ce sujet prigre de rappeler le

Adresse télégraphique: STATSSERUM, Copenhague.
Téléphone: Central 2835.

Ref. cece he Biles ecee

 

Air- Mail.

THE STATE SERUM INSTITUTE
Department of Biological Standards

{n any further communication on
this subject please quote.

Copenhagen S.,........... NO Vea Gentes 19.45
(Denmark)

Dr. Joshua Lederberg,
Departuent of cenetics,
University of wisconsin,
MaADIS GN, Wisc.

UsSehe

 

Dear Dr. Lederberg,

ky friend Prof. Mogens westergeard {he is a geneticist and did some work
with Nitchel at Cal. Tech. as you may recall) and myself recently discussed
some of the details in your recombination technique.

We thereby got interested in trying out some modifications which -— with
luck - might increase the yield of recombinants. %e should therefore be very glad
if you could provide us with some of the mutant strains with which you have
worked yourself; among the mutants on tne list in your paper (Genetics 32, Be 505,
1947) I have thought oi the following as suited for our experiments:

kK 12 (wild type)
B- 58

TT 679

Bk 58-161
TL 679-680

TL By 410

BN Vir 440

TL By Vir 441

; I guess you still keep these strains and I should be very glad if you
would send them to me whenever it is convenicrt for you.

with kindest regards to yourself and your collegues at the department.
Sincerely Yours,

urate,

CO. Maalae.