THE UNIVERSITY OF WESTERN ONTARIO
FACULTY OF MEDICINE

 

DEPARTMENT OF BACTERIOLOGY AND IMMUNOLOGY
THE HAMILTON KING MEEK MEMORIAL LABORATORY

375 SoutH STREET,
LONDON, CANADA

November 9,1950

 

Dr. Joshua Lederberg
Department of Genetics

The University of Wisconsin *uyeues
College of Agriculture TLT¢S sBeus [woTuyooy. yeum omoo7zeso
Madison 6 aoos [TJM nof sune we J *syserzU0O poo

esey pue daxeys ete sydersozoud unox *g*g

Dear Lederberg,
Many thanks for allowing me to share in the pleasure of
looking at your interesting coli preparations.

The chromatin structures of H 226 are impressively larger
and optically better re xlved than those in the haploid strain. Murray and
I both feel that some c. the bacteria in the picture of # 226 lo indeed
more like B.cereus than anything we are used to find in ordinary strains
of E.coli. Nevertheless, the number of chromatinic complexes per
bacterium and the number and mode of arrangement of rodlets and granules
in individual complexes does not seem to exceed what is normally *ound in
large bacteria. A glanc at figs. 60 and 61 on plate II of ByDel._ orte's
article in Adv.i.Genetics III,(1950) will bear this out. I have indicated
with 7 and what I believe to be bacteria with comparable
chromatinic configurations in your two photographs. "cf.fig.3,1944" and
"figse5,6 1944" refers to plate 5 of my 1944 paper in the JeHyge In short,
I think there is probably the same number of granules and dumbbells per
nuclear structure in both forms and that the two strains differ only in
kim size.

I enclose a picture of S.sonnei, from a preparation by
Murray, as a further illustration that the H 226-type of nuclear structure
igs similar to what is normally found in relatively large, but presumably
xargxa haploid, bacteria. The preparation had not been hydrolysed and was
Stained with thionine, hence the nuclei are shown in relief, Owing to the
presence of about 7 musSpik meg/ml of chloromycetin in the medium the
arrangement of the nuclear structures in these cells is, in places, slightly
abnormal {you will note incipient snake formation) but the detail of
individual nuclear complexes is still the same as in normal material.

Are you satisfied that the preparation of K 12 shows all
there is to be seen ? The photograph looks a bit as if, after the osmiun,
the cells had & not been allowed to dry, and thereby flatten out, long
enough before being fixed with alcohol. Fully flattened cells might show
one more closely resembling, en miniature, the chromatin structures of
H 226.

Hoping that ny impressions are not too much at
variance with your own conclusions and with
renewed thanks

sincerely yours

C. 7b Phen