April 28, 1954

Dr. Neal Groman
Department of Microbiology
University of Washington
Seattle 5, Washington

Dear Dr. Groma@:

Thank you very much for the manuscript sent amder cover of your
note of the 7th. It was indeed useful for the discussions at the Oak
Ridge meting, and will be even more so for the formal paper I am now
writing as a general review of "genetic recombination in bacteria".

Have you sent, or do you plan to send, this paper to the Journal
of Bacteriology? I am interested to know how best to cite it (though
personal colmmnication, or to be published, should do) but also as I
would like to see it there on behalf of the Journal.

This is a very well written ms., and I could find little to criti-
cize either in form or in substance. Mynmost pressing suggestion on the
form is that you delete the section from pp. 7-9 as indicated on the
attached review sheet.

As to concept, I hope I will also have clarified my notions of
"transduction# as the term applies to the present case vs. Salmonella.
To my mind it id far less important that cne discuss whether this is a
transduction, and better to emphasize the descriptive conclusion that
the role of the phage here is quite different. But as I have tried (not
altogether successfully) to keep clear, genetic transduction is defined,
without reference to the role of phage, as any process of trananission
of genetic fragmenta from one cell to another, as distinct from fertiki-
zation, where an intact genome is transmitted to a zygote. Thus the
Salmonella case, where a phage acts as the vector of the fragment, and
the pneumococcus transformation, wherein no vector seems to be nesded
other than the hand of the chemist, are hoth sub-categories of transduc-
tion. |The term was developed before it was as clear as now seems that
the pn. t. was in fact a transduction in this sense]. what to call con-
version depends on how one defines"genetic Bragment"— your option.
"Trangformation" per se meaas only "change# and has, for example, been
applied equally to the mitations from S to R as to the more interesting
R to S in pneumococcus,

Yours sincerely
$

oshua Lederberg
Groman—- Evidence for the active role of bacteriophage in the conversion

of non-toxigenic Corynebacterium diphtheria to toxin production.

P L
1 8
4 11-14.
7 10
to
9 3
5 3
5 last

"intimately related tot is needkessly vague; I infer you mean "an
immediate consequence of",

This is the same as above. The quantity of phage released by young
cultures of lysogenic Salmonella is often (but not always) too small
to effect < deteciable number of transductions 3 you have a more sen-

sitive system. I would dele this.

I think this is overdoing the argumnt, and likely to do more harm
than good, ant would therefore leave it all out. Your conclusion is
certain on the following brief argument: In Salmonella, the vectorial
role of phage is shown by the separability of infective and transduc-
tive functions, i.e., not every particle accompliashes any particular
transduction. In diphtheria, your well designed axperiment failed to
separate these activities despite several single-plaque isolations 3» 89
that one can conclude that the phage per se invariably transforms the
recipicnt. Since transduction is defined(without reference to phage !!)
as a transmission of a hereditary fragment from one cell + another,
the question is ye tt¢* not so much whether conversion is a transduction
(which depends now on whather you chcose to regard the phage itself as
a hereditary fragnent) but the role of the phage in the two systens,
In Salmcnella, the phage is a passive vector: in dipgheria, at the extreme :
tre nace would have to be regarded as the genetis element itself.
This argument relies on the implicit assumption that the C7 is igself
convertible by phage grown on C7 or C4. Ctherwise » two possibly non-
homologous nontoxigenic strains could still interact by transduction
(Cf. restorations of motility in Salmonella in Stocker et al.).

Is the #OP of this system known?
10-11
Lt

16

19

DoD 2
20 9~10.

Excellent!
l, Might be clearer to write "and had not been propagated on C4"...
354 Again the past perfect "phage (3h) had been propagated" would
be clearer.

Discussion of Hyp. 1: The DNASE argument is meaningful only on condition
that the accessory factor has to he DNA, which of course it would not.

I would leave this out and point merely to the high dilution that you
must be able to allow whan you recover toxigens from single plaques.
This would necessitate an incredible excess of the accessory factor.
Hyp. 2 does not mean mch except in relation to the criteria that one
might employ to separate phage "itself" from each particle. You might
find it advantageous to use ultraviolet light which, in Salmonella,

and lysoggnizing

attenuates lytic/moh faster than transductive function. Your heat empt.
(617) is equally useful; the data should perhaps be recorded in the future.
10 I do not understand your possible reservations ebout chromosome—
linkage of lambda in EF. coli K~12, My wife and I did have to point out
the remote possibility that only an indispensable part of the prophage
was bound, and the rest still cytoplasmic {though there was no indication
of it]. App&eyard (CSH 1953) has since shom that at least one genetae
marker of the lambda is similarly bound, and this should clinch it. I agree
you have no way of telling about this in diphtheria, and it would be
ineautious to leap to generalization from this one casee

] Sp. compatibility

This would seem to read that "conversion is an induced change", I am

sure such a statement is deletable,

20 14-16. This observation goes back to den Dooren de Jong, I think ("mtilate" coleé-

nies).