May 23, 1958

Dy. Charles Yanofsky

  

Dear Charlie:

I'm sorry I didn't remamber to discuss this with you when we met.
laca Cavalli, Esther and I have been working together here trying to get
a good mapping of the Gal loci, with rather discouraging results for
various technical reasons, “e are now trying to adopt interrupted mating
to the purpose. But the different autanta are so close together, and the
frequency of multiple crossing-over is so high, that we still have troubles.

Luea found that at least one tryptophan mtant is fairly closely
linked to Gal, and this would help ug a great deal. But the one we're
using (anthranilic™) is not too satisfectory on account of reversion. Also,
it may not be the closest to tha Gal region.

It might be especislly helpful if we couled try 2 variety of other
tryptophane mutants, especially a deletion type. Could you send us a
reprosentative set? It would be a complicated mtter to explain the optimal
conatillation of cther murkers. I¢ you have any that are also TLB, , 80 r,
mich the better! 2

Pos.

oye oy ome A

I don't doubt that any use we can extract for Gal ‘napping would be of
some advantage to your tryptophane program - we will keep in closa touch
with you and you are of course welcome to any of the stocks we set up.

As Cavalli's vieit is limited in time, I would especially appreciate
it if you can help us out as soon as convenient.

There's no definite word yet from Alway; I hear he has been officially
named as the Dean.

Yours,

Joshua Lederberg
Professor of Medical Genetics

JL/ow