Jamary 31, 1952

Dr. Werner K. Maas
Tee. Res. Lab.

411 FE. 69 Street
New York 21, N.Y.

Dear Werner:

I think that Msther and I had already written to you some time since
about our negative experiences with the infertile pant. mtants you pro-
vided. We worked primarily with your K1-QT~h. I take it that the sequence
of origin of this strain was K-12 -—- KIT ~—- Kl -~ Kl-QT —- K1l-QT-h. We
vere and continue to be unable to cross this with any of our stocks,
haploid or diploid. Wechave not examined any of the TS stocks; perhaps I
should try to make a 13,/+ diplcid for you even without suitable linkage
information.

Esther's infertile combinations haveturned into a rather remarkable
story which we have, however, been unable to relate to your cbservations
on pant. Her atock, W-1321 (ultimately from 58-161) may be designated F-
(ig contrast to type, ¢.g., 58161, Ft). Fe is a self-incomatibility
factor; we have also picked it up in some other lines. F~ x F~ is com
pletely infertile. F+ x F+, and esnecially F+ x F- are, of course, fertile.
To make a long story short, F+ is transmitted to F- cells with very high
efficlency when the two kinds of cells are mixed if 2 complete medium.
For example, 108 cells of 1321 + 10° 58-161 incubated for one hour, then
plated out, the 1321 colonies reisolated by fermentation markers, gave about
10% ¥-1321 now P+. The acquired F+ is genetically stable as is the original.
Filtrates end the BBB (Bernie's bacterial bundling board) gave no transmission
eo far. When 58-161 is grown with heavy aeration, the cells are a phenocopy
of F~. A small proportion may be irreversibly F-. I susvect that under
conditions of rapid growth, the F+ does not keep pace with the cells (like
kappa in Paragecium a la Preer.) F+ igs not lambda. Anyhow, your K1QTh is
also F+, as shown by transmission to \f-1321.

“hat I wanted to ask you about particularly was the surprise, turned up
in the lastnamed experiment that KIQTh is lysogenic for a phage active on
W-1177, and therefore not lambda. Since all of the other K1 and KiT stocks
you sent me behave the same way, I would assume that the phage turned up
between K-12 and the single K1T (ts) which I infer to be ancestral to all
the cultures sent. The phage is diffaécult to see; I noticed it only on
EMB Lac + 3m on which the KiQTh was inhibited. I would appreciate 1t if you
could either verify the point of origin, or send me your K-12 and KIT. Can
you offer any suggestion as to the possible origin of the, phage, except
that it might be some sort of lambda mutant? Vas KIT ever exposed to foreign
bacteria? As I remember the “ strain was not lysogenic, but I shall have to

heck that in.
enee ay aga Sincerely,