UNIVERSITY OF ILLINOIS

DEPARTMENT OF BACTERIOLOGY

362 NOYES LABORATORY OF CHEMISTRY
URBANA

Deee18,1951
Dear Joshua:

I have got the job to answer your letter of Dec.9, since
I have been the last to read Boyd's naper.

It is hard to explain lysis inhibition on the basis of
a phage heterogeneity because of this: if one infects with
very low multiplicity using Tér*,without diluting before the
lysis, one does get lysis inhibition, presumably due to the
readsorption of _the first phage to be liberated onto the célis
which have notYlysé ey. If phage were heterogeneous, the
first phage to apvear should be of the rapidly lysing type and
therefore could not lysis-inhibit.-Also, if a no matter how
large multiplicity of phage is adsorbed in a very short period,
no lysis inhibition occurs.

According to old Doermann's paper a first single infection
with r followed by r* does not lysis inhibit. Still these data
should be checked with better techniques than those which
Doermann could use at that early time. On the plates, one
would say that a rt? plaque inhibits adjacent r plaques, but it
is hard to interpret what 1s going on on the plates.

As to Boyd's paper, I have been puzzled a lot, in trying

to find an ihterpretation able to explain all his data.

If it is only question of heterogeneity of the phage (and
“predominance” of the lysogenic one), one should expect to find

within a certain range of multiplicity a linear relationshin
between induced lysogenic and vhage input. His data are too scarce
to show such relationship.-If it is only a question of multipli-
city, one should not find this relationship.- From table III,
assuming this last hypothesis to be the good one, one can
calculate that approximately 2.5-3 particles are necessary to
make a cell lysogenice Then, in the .exreriments of table I,

(for instance in columns 10? ana 108 vhages/ec) one does gf
not understand why there is such a big loss of cells. Since

they get infected presumably after they have gone thru a few
divisions, one should exnect under these conditions that a
multiple infection of 2 or 3 phage particle on a cell adjacent
to one which met one phage particle and was lysed, is a very
common occurrence, following in most cases a lytic infection.

It is quite possible that there is some relation between
induced lysogenesis and lysis inhibition. Still, from what
we know on lysis inhibition, I have the impression that the
delaying block occurs at a later stage than one would expect for
a block supposed to make the multiplication of the prophage
indefinite (see for instance the data of Cohen on DNA in mul-
tiply infected cells).

I had news of you from Seymour. I might be able sometime
to win my natural laziness and come up to visit you.

Best regards,
sincerely

fre