DEPARTMENT OF BACTERIOLOGY AND IMMUNOLOGY
HARVARD MEDICAL SCHOOL
- 25 SHATTUCK STREET

BOSTON 15, MASSACHUSETTS

November 13, 1957

Dr. Joshua Lederberg
Department of Genetics
University of Wisconsin
Madison, Wisconsin

Dear Dr. Lederberg:

In our course called Medical Sciences 201
the students carry out some experiments in
recombination with E. coli. We should like to
have them this year compare HFR frequencies
with standard strains.

Would you be so kind as to let us have
an HFR auxotroph that is streptomycin resistant?
We have on hand:

Strain K-12 = wild type strep sensitive F+
" n

.~ Strain W =
; 11A16 - req. isoleucine " F+
aaa 4 W1817 = reqe leucine strep resist. Ft
ny threonine
r thiamine
W1177 - req. leucine " F-
threonine
thiamine

We shall be very grateful for your assistance
and hope it will not cause you too much intone
venience.

-M Ft

JS ly- tb . R Sincerely yours,
Jw 7142 dem 7 Ma, ‘ } hevtdh Jove

 

Vata etE fr thy stilun of s Foam W
Ste

Harold Amos
Ctewbess 34. Pp. i emer

ogoreti “SVU