THE JOHNS HOPKINS UNIVERSITY
SCHOOL OF HYGIENE AND PUBLIC HEALTH
615 NORTH WOLFE STREET

BALTIMOGORE=—35. MARYLAND

DEPARTMENT OF BIOCHEMISTRY April 23; 1958

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

Dear Josh:

We have been unable to obtain any transformations with the strain
WH-8(SnR), but this was not too surprising since WH-8 proved to be
sensitive to 50, /ml. streptomycin. We have, however, isolated a
streptomycin resistent strain of WH-8 which is resistant to greater
than 50 ,//ml. streptomycin, We shall test this strain, but 1 think it
not likely to be successful.

The hospital bacteriology group tested the WH-8 and have identified
it as a gram positive diptheroid. In addition, we have isolated a
Similar, if not identical, strain from our stock Rd culture, However,
Rd clones even after several passages do not show any WH-8-like organisms
after subculture in Penassay broth. In fact, they do not produce
appreciable coutfon subculture with PA. In view of these tests I
conclude that WH-8 and the organism we isolated are the result of contamina-~
tion.

I have arranged for United Airlines to handle the shipment of a
large thermos packed with dry ice containing competent Rd cultures to
Madison, The container should arrive on North Central Airline 5:30 p.m.
Tuesday, April 29, There should be sufficient dry ice to hold an
additional 2h hours, but it will be necessary to maintain the cultures
at dry ice temperature if you wish to hold them in the competent state.
You may keep the thermos for months if necessary since we have no need
of it, but I should like it returned eventually.

The cells should be diluted about 1/30, i.e., 0.1 to 3 ml. broth,
and the T.P. about 102, then incubated 30 min, at:36-37°C and further
diluted 10° to give a reasonable number of colonies per plate.

The procedure recommended for these cells follows:
2.8 ml. broth.
O.1 ml. T.P. diluted 102,
0.1 ml. cells.
Incubate 30 min. at236°,

(1)
(2)
(3)
cD)
(S) Dilute 103 - 9.0 ml. to plate.
Page 2

(6) Add +10 ml. Levinthal agar containing 1¥/ml. DPN.
(7) Incubate 2 hrs. at 37°.

(8) Layer with +10 ml, Levinthal agar containing 500 Y/ml. streptomycin.
(9) Incubate plates 16 hrs. or moreaf 37 °c,

Good luck and best regards,

Sincerely,

Sok

Sol H. Goodgal

SHG: csb