DEP- OF BIOLOGY
WSACHU~ IJJSTmOF TECRMOLCCY
   CAMBRIIGE3~,MASSACIIuSETl's

February 20, 1961

Dr. Jacques !&mod
In8titut Pasteur
25, Rue du Dr. m3.1~
ParfsXV, France

Dear Jacques,

Your mmuacript, which was avidly read, pmmpts ma to write about
several thbgs.  In the firs-t place, I expect to pstop in Paris for
two or three days at the be@xning of April, with Zella, on our way
back from Israel.  Would the dates of April 3-k-5 be convenient for
avisit? Atthattims I wouldlike alsotomake scme prelirni~
arrangements for spending; part of the acadoraic year l9%?-63 at the
Pasteur Institute.

COnt?Wning your manuscript with Franqois, would you please let ma
knowwhere itwill. appear.  I wish to quote it in my paper for Israel;
in fact> reference to this paper will make it possible to eliminate
several sections that I had already started to put in.

In connection with your paper, there are a number of points of interest
inour cxrrentwork.  'Gle have evidence that the level of B-galactosidase
formed in various Shigellas reflects diffemnt activities of a genetic
region located inor near the opescator.  Recombinantsbetween Shigella
and E. coli mar the 2 region often have intermediate levels of enzyme.
Mel is going to test the enzyme produced by the parents and tiae hybrids.
I would incriMnate the operator itself, were it not that the pemease
level is unaffected by the Shigella "operator" region. In addition,
we found t&t mmme3. of the z' strGins (rriostly yours) me low in
permeass, ~5 you no doubt have noticed.  The y- strains, on the other hmd,
sWmto ha.* full level of ensyase,  It seems reasonable that there may
be a segmental effect in the direction o+z+y.

Another matter of some interest is that the production of B-galaetosidass
isr imtediately stopped by infection with pm T6, whether the gene is in
the chrcmoscrrrser, in the F factor, or in a newly-entered Pl-lac phage.
This shows that all DNA except that of T6 itself ia destmyed, irrespective
Of location.

Finally, the question of the production of' enzyme after transduction has
apparently been solved in favor of the "abortive transduction!' theory.
This was done in a rather cute way involving double transduction. We
are now finally writing this up, while doing som more attempts to count
directly the cells that produce enzyrae.  I shall tell you more in Paris.

With best regards to you and all other frie&ds,

Xncerely,

S. E. Luria