Decenber 26, 1955

Dr. P. R. Edwards
Box 185
Chambaes, Ga.

Dear Phil:

Thanks for your helpful notes on 8. "java" N97. One of my stuients,
Tetsuo Tino recently found an exceptional b,i: enx resplt from the familiar
™2 —-x abony, and we are far enough along with it that I think we should
combine its analysis with that of N97. This exception behaves ac far as
if it 1s H,> H, + H,°™, and differes from corresponding derivatives of

N25 and N97 primarily in showing adauletenesiz® sear chs snternate), and the

b. If the case holds up, it would be analogous to so-called "unequal crossing-
over" which is known in Drosophila, and would help to understand the origin
of N25. I hope to send you some of the derivatives to verify the serotypes,
and will be grateful for your commnt on them.

As to 0-§ in abortus-equi, my reserwation was only whether its occurrence
should be ascribed to transduction, rather than apm other more inter esting
process—— in fact we had some indications that} might relate it to the lyso-
genic conversions of Uetake and Isekt. By the way, I just received a reprint
from Iseki that the 0-1] antigen is in fact converted in just this way-—— which
is in line with my distrust of Kauffmann's offhand claim of "trmsiuctdon" of
0-1.

To turn to another subject,

Wetin I don't see what the linked transduction of two markers has to do
with efficiency. If you are following a Linked pair, the second marker will
(by defihition’ go along in a high fraction of the transductions for the first
one. Any given transduction 4s accomplished by only one phage particle. It does
not seem unreasonable to me that the m&fatse efficiency of transduction will
vary widely from one system to another. My own experience would be gute con-
sistent with a frequency of linked transductions of H Fla, of about 10
(and with the right combinations, almost 1075) per phage particle.

What I wanted of you right away, Phil, was your possible advice about Dr.
Frits Orskov, and his wife Ida, from Keaffrann's laboratory. As I have hinted
with you and Bill Ewing for some tims, we would like to expand our efforts at
immunogenetic analysis of E. coli by crossing methods. I mentioned this to
Keaffmann also, and he is recommending that the @rskov's apply for a fellowship
to spend a year with me. My munvarsat correspondence with the Orskov's so far
has bean quite agreeable, and I would not hesitate? to have them come on their
own finances, but it may be necessary for me to find some local support in addi-
tion. Before I accept this responsibility, I would like to get any further ad-
vice or information that I can. Have you been acjuainted with them? Con you
suggest any one else who would be better suited to eome here? fny ides you
may have on this would be welcome.

With best wishes for 1956, Sincerely,

Joshua Lederberg