January 2, 1953

br. S. E. Luria
Bacteriology
Uo? Hiincis
Urbana, Dlinois

Dear La:

I just had a letter from Benzer about a "UV conference” at lurdue
January 25-26. I want to ask whether you are planning to go (and if so, who
with you). The reason ly that we will be driving en route to Chamblee, Ga.
(via New Orleans, perhaps) and had planned to stop over at Urbana on the
25th or 26th. Spioer will be accompanying Esther and ae. There are a few
new developments on lysogenization/transduction I wanted to discuss with
you and Joe.

we did an X-ray experiment, but 200,000 r (in broth) gave only one
decade of attenuation of plaque-formation, and less than that of PA, so
this dcea mt seem very promising. You mentioned something about imitating
the indirect effects with peroxide. Alao, [{ know there mast be somewhere
a more detailed account of phage-inactivation with muatard, but I cannot
find these offhand. With UV, lysogenization can be completely separated
from transddction, und I have go fur no evidence of having nad uay access
at «11 to the included genetic miterdal PA. In view of the asoumed locus
of indirect X-ray effects, it is rather unlikely that we will get very far
with these ghther, but even the negative information might be useful. [Do
you have the supply of reprints of Watson II?)

Some of the ‘ayscerles of our lyscyanizution—transduction correiation may
be clearing up. We think that within the progeny of single infected cells
transduction cecurs in the same clones as are lysogenized, The non-transinduced,
phage~sensitive survivors in these experiments are the other progeny of the
infected cells. A rather useful tool haa soma up, a lytic mitant of PLT22, 22V
which has the property cf being interfered with by 22 iteelf. Thus, at low
miltiplicities one can recover as many bacteria resistant to a challenge of 22V
ten minutes later aa one has added particles of 22. It appears as if all of
the transductions are protected against 227, although only enougl PLT22 1s added
to protest 10% of the total bacteria. This I think may lead to fairly rigorous
procf that all transductione involve phage-lafected bacisria, wiich ia signifi-
cant when 1ow multiplicities of infection are involved. As with lambda, infected
Salmonella celis give rise to mixed, contaminated colonies, With higher milti-
plicities of infection, tha svlonies «aay be nearly pure lysogenic, but even here
there is a suspicion of « residuum of sensitive cells in the "lysogenie"™ colonies.
Under wy conditions, I have been getting negigible killing with any multiplicity,
though Ioan fabrly ccafident of Sordtn rssult dn other, are casual expts,

Sincerely,

Joah¥a Tadarhere