November 26, 1952

Dr. S. Granick
Rockefeller Institute
York and 66th

New York 21, N.Y.

Dear Granick:

a rota
oan

,G% J

I am enclosing a subline of strain K-12, W250, which should he
eminently suitable for ycur bicehemical mitation experiments. You ex-
pressed some hesitation about the possible influence of lysogenic phage,
and for this reason I am send you this strain, instead of K-12.

WD lacks the phage, lambda (and is susceptible to it), but is proto-
“trophic. It should be eminently suitable for recombination analysis, but

I auggest that we constlt about this in more detail when that occasion
arises, so as to be sure that you have in hand the bast possible parents.

If you should accumulate any number of auxotrophic mitants as a by-
product of your porphyrin studies, I will be grateful to hear about it,
and may possibly ask you for som éf then for other genetic studiss.

I am still a little sorry, pethaps, that you did not elect yeast, but
hope that the porphysin situation in E. coli works out for you.

Under separate cover, I am sending some reprints that may be of some
relevance to this problem. Thank you for keeping ne up to date on gours.

Yours sincerely,

Joshua Usderberg