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: cs Genstics Department
i a. . University of Wisconsin
oo , Madison, Wisconsin

an oe _ March 9, 195h

“De Germaine Coben-Bazire
‘Service of Microbial se laeaiial
‘Paster Institute _

‘23 EueDr. Roux

Paris 15

‘ FRANCE

Dear Dr. Cohen-Basires — a

72 > qathin the past few days I have enjoyed a visit from Jacques Monod,
and we have discussed in some detail the work that you have done with tha
constitutive mutants of Z, coli. In particular we have agreed that cortain

: aspects of this work might p rofit from a collaborative examination,

-One feature of the report that you have published in the Annalesof

“the Pasteur Institute has been extremely puzzling to us, namely the recombin=
‘ation type that you describe as basing Lac~ constitutive. We have not ourselves
encountared such a type in the course of crossing or mutation studies, It
_dis, of course, entirely pessible that this is a matter of the limited mmbers
that have been examined, It would, however, be considerable reasaurance to
us if we could examine by our own techniques the culture such as you havs
deacribed in your papsr. Would 1% be possible for you to send to us for
this examination two such cultures, as follows: 1) tha recombinant dese
-eribed as having been obtained by crossing Lace by constitutive in E. colt

' Xel2, and the similar type that you deacribe as having issued froma 7
.mutation experiment, I am sending duplicates of this letter to Paris and

_ to Berkeley in hopes cf one of than Teaching a proper destination Lor tha
tuifilinent of this request, ;

——e | Jacques, if thie letter reaches you, no further ‘comment would ‘be

_ “necessary, We had dona a few additional experiments by way of isolating
-' lactose-negative mitants from our constitutive stock, but none of these
have proved to be the Lace constitutive combination.
ok an . I would be grateful for a reprint of the paper referred to hater
- we do not seen to have received a  SOPy before, shou I would not inzist

Yours sinceraly,

Josmua Lederberg

 

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