NEW YORK STATE COLLEGE OF AGRICULTURE
CORNELL UNIVERSITY

ITHACA, NEW YORK

 

LABORATORY OF BACTERIOLOGY

July 1, 1949

Dr. Joshua Lederberg
Genetics Department
University of Wisconsin
Madison 6, Wisconsin

Dear Josh:

Unfortunately your letter of June 20 did not reach me before
I left for my fishing trip.

I do have some information about H-168 and xylose. You will

remember that I did not have mech luck isolating the heterozygotes from
H-168 on EMS lactose. You suggested using either EMS mannitol or xylose.
We had just a little bit of xylose so I did use both media and suc-
ceeded in isolating the heterozygodés® cells on both media. Hence, at
the time I received H~168 from you, it was heterozygous for Xyl. Of
this I am absolutely positive. I subsequently used EMS mannitol to min-
tain the culture since we had no xylose and it is much more expensive.
I am going to plate from your original slant on EMS xylose today, and
will let you know if any Xyl+ colonies show up. I hope this will help
you formulate what might have happened. I think your explanation of a
new cross is a very probable one.

In regard to the "8"~217, my point was this: the only lethal
occurring in its immediate family tree was its sib. Hence, if the
segregation is associated with a lethal, it mst have ended up in that
particular sib. This is different from some of our earlier instances.
Why? Was "8"-108 a uninucleate het. cell, while the earlier were miti-
nuclear?

Now about H or W-206. I have been using EMS, lactose, and
maltose in attempting to isolate the heterozygous cells. What with trips
and all, I have not done too much with it, and I think I have some hetero-
zygous strains established. However, it seems that many of the colonies
picked from EMS are not heterozygous. What is the complete genotype of
this culture? Is it also heterozygous for B, M, T, L, ete.?

I will let you imow when I feel that I can handle H-215. [
should be back from Oak Ridge about July 20 or so, but may have to go
on active duty in the Navy for a couple of weeks in August. All in all
it looks as thoughitis going to be a rather broken up summer for me, but
I am anxious to continue this further so long as it appears profitable.

Very truly yours,

MRZ.-EBF M. t Zelle