Berner

September 18, 1955

Dear Miriam:

I want to thank you for sending us the lyophil tube of Y-~87, as requested
via Kay Wilson. I would have aritten sooner but wanted to check some of the
features of this isolated.I was very pleased when Dot Gosting was able to iso-
late both an M~B*+ and an M-B-. As you may know, there has been some difficulty
on the history of the B- (biotin)requirement in derivatives of Tatum's original
58-161, and this is the first time in several years we have been able to charac-
terize that B~ requirement. We now have a clue (in differences in colony appearance)
on how the B- requirement came to be lost, and how to look for 1t again in older
cultures of 58-161. Do you think you could dig up old tubes of 58161 and its
imuediate derivative, Y~40, so that we can check on this point? I would appreciate
having the dates (if available) on the Y-87 as well as these other lyophils, to
try to reconstruct the history. If you wish, we will be happy to send you back
replacoment tubes on any of the repurified isolates. ‘These cultures happen to
be rathe» laportant in the history of the crossing work on K-12 or the matter
wouldn't be worth bothering about. It seens to have been years since we've
seen you and Bave— I'm sorry we didn't get out to Lansing, but there was too much
else in the way.

Sincerely,