FEDERAL SECURITY AGENCY
PUBLIC HEALTH SERVICE

 

IN REPLYING, ADDRESS THE

ruberculosis Research Laboratory,
411 East 69th St., New York 21, N. Y.

July 16, 1951.

Dr. Joshua Lederberg,
Department of Genetics,

The University of Wisconsin,
College of Agriculture,
Madison 6, Wisconsin.

Dear Joshua:

I was glad to hear that the visit to Wisconsin can be
arranged. I plan to arrive there on Tuesday, August 7th, and shall
probably stay for about a week if that is all right with you.

My plan for the things I want to do in your laboratory
coincides with what you had in mind» I am interested mostly in
obtaining a heterozygote pant*/pant’® which is stable enough so that
it can be used for enzyme experiments.

You were correct in your statement about the loner activity
of the pant’® extracts. I had mentioned that to Bernie a while ago
and he must have told you about it. However, lately we have obtained
much more active pant® extracts. The enzyme activity of the acetone
preparations varies a great deal from one preparation to another,
voth for the wild type and the temperature sensitive extracts, Our
last few temperature sensitive preparations have been as active as
some of our better wild type preparations. Although I find this
variability in the acetone preparations disturbing, at the same time
I think it is possible to obtain a preparation of the postulated
heterozygote in which one can distinguish the, two enzymes.

So far I don't haye any linkage data on the pant’? locus.
All I kmow is that the pant 5 mutants recombine with your strains
58-161 and W677. I have started some crosses with W-677 in the
presence of pant and shall try to obtain the linkage data with the
fermentation characteristics you suggested in your letter, Since
these strains contain only one marker in addition to the pant’ require~-
ment, I have alse started some penicillin experiments to put additional
markers on these strains. As scon as I have the doubly marked strains
I shall send them to you together with the singly marked ones. If you
have time, I would appreciate it if you could carry out a cross to
Dr. Joshua Lederberg July 16, 1951.

determine the linkage of pant*5; we could then compare notes on our
data. In view of my lack of experience in doing linkage studies on
K-12, this would be very valuable for me.

I am not, qpite sure that I understand why we have to know
the position of pant ® before we undertake to look for the heterozygote.
The reason as I see it is that pant’® may be located in the deficient
region of the chromosome, near mal = or in some other region of the
chromosome which does not behave normally. The way I visualize our
experiments is, first, to cross a suitable pant’® strain with a Het
strain carrying fermentation markers, and then test the prototrophy
on EMB-lactose (or other sugar) medium, and look for variegated
colonies. I would appreciate it if you could outline to me your
plan for these experiments in some detail as I am not sure that you
have @ similar procedure in mind.

I am looking forward to hearing from you.

With best regards,
Sincerely yours,
leans.

Werner K. Maas

WEM/h2