YALE UNIVERSITY
OSBORN BOTANICAL LABORATORY
NEW HAVEN, CONNECTICUT

February 24, 1949

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

Dear Josh:

We recently finished our synthesis on "ONPG" and am sending
some under separate cover. Thanks very much for the ones you sent us.

We haven't as yet tried many inhibition tests on lactase but
have dealt primarily with bp olati on of the enzyme. Landman believes
at the moment that he has # crystalline. I won't believe this until
I see it repeated a few more times and in larger quantities. I am un-
able to send any crystalline but I can send a pretty well purified
Neurospora enzyme, if you still want it.

Your grapevine isn't very efficient, since I have perhaps one
or two more lactose negative mtants but certainly not wholesale. We -
have been unable to achieve a really satisfactory selective method
of obtaining these mutants. Our difficulty at the present time is
primarily that of devising an easier method of getting any mutants at
all. We are feeling more hopeful at present and using m-ray irradiat-
ed ascospores plated out in sorbose. We have what appears to be a
somewhat better system than the lactose system amt a system dealing
with the conversion of tryptophan to indole acetic acid. We have
been more successful in getting clear-cut mutants to this character.
It appears more straight-forward than lactose.

Any more dope on your diploid?

Best regards,

Sincerely,

David M. Bonner
Associate Professor of Microbiology

DMB