YALE UNIVERSITY
OSBORN BOTANICAL LABORATORY
NEW HAVEN, CONNECTICUT

November 15, 1949

Dr. Josh Lederberg
Department of Genetics
University of wisconsin
Madison, Wisconsin

Dear Josh:

I trust that the weather of Wisconsin has been as pleasant and
nice this fail as ours. It is stiil mildly like spring.

I am writing to see whether you would be willing to send me
jac” strains which are genetically distinct from Y-53. As you know, we are
interested in the lac™ character in Neurospora, and last spring started some
work on Y-53. we started on Y-53 since it seemed the easiest organism to
investigate the mutagenic effect of specific enzyme antisera. We have, in the
course of this serological work, run across some data that makes us anxious to
try some other geneticaily distinct lac~ strains.

the substance of our observation is simply that there is a
serological difference between K-12 grown on glucose and on lactose in terms
of the antilactase activity of the antisera, Y-53 does not grow on lactose,
yet when grown on glucose gives antisera having antilactase activity. We
would Like to know if this is true of other lac™ strains, and would appreciate
any culture you might send.

we find K-12 makes lactase on most carbohydrates, such as
maltese, galactose or even glycerol. Indeed this is true of Neurospora as well.
I wonder if’ you have any dope on this.

with pest regards to you both,

AS ever,

David M. Bonner
Research Associate