..._ INSTITUTUM JAN 15 1965
SERO-BACTERIOLOGICUM
UNIVERSITATIS

HELSINKI Helsinki January 1ith,1955

Prof.Jd Lederberg

Genetics Department

Stanford University Medical Senool
Pasteur Drive

Palo Alto, California

US a

Dear Josh,

This is just a manuscript of some of the work
I did in the Lister Institute last year. The Salmonella abony
F+ & Hfr system is surprisingly good giving reasonable recombinatior
even between Salmonella "species" snd between Palmonella and coli!
I do not think that this kind of work on O-antigens could have
been done with otner methods in Salmonella; I know that colicins
give too Tittle recombination under the circumstances, and the
typhimurium tifr s of “Zinder and Demerec sre too weak as well.

In some other crosses we found a novel type
of O-antigens in Salmonella, which seems to be 4 true between-form
of Smooth and Rough. The proposition is that these semirough strains
have only one repeat unit on their sidechains, hence much less
Specific reactivity and impaired stability in saline. Tnere snould
be @ paper together witn Nikaido 3nd otners in the January PNaS
about this. ,

Olli and I received an NIH grant for three
years, which we are very happy about. a new laboratory for our
institute is being built here, where we can @probably) move in
next year, and this makes the funds even more useful. Je suspect
that you nave been asked about our projects,and wisn to thank
you sincerely.

est regards to “stnher,

yours

P:Helena Makela