CENTRO DE INVESTIGACION Y DE ESTUDIOS AVANZADOS
DEL
INSTITUTO POLITECNICO NACIONAL

APARTADO POSTAL 14-740 MEXICO 14, D. F. CABLE: POLINVEST,

 

DEPARTAMENTO: Bioquimica

REFERENCIA:

Dr. Esther M. Lederberg

Department of Genetics

Stanford University School of Medicine
falo Alto, California 94304

U. 8. Ae

Dear Dr. Lederberg;

Iam very glad to send you this “preliminary
‘report" about our work with the Hfr S- abony strains that
you sent us

The Hfr sw-1444 has worked beautifully. The
results obtained trying to locste the position of the
structural gene of pyruvate kinase are very clear and
reproducible. As a matter of fact I can tell you that we
have placed it, tentatively, at 2% minutes of the point of
entrance of the SW-1444 chromosome. :

however, strains SiW-1418, SW-1403, Syw-1452
have not worked at all. I understand that their recombination
frecuency is lower than that of SW-1444 but I suspect that
by some reason they have lost their Hfr character.

I am really ashamed of bothering you again
but, will you be so kind as for sending me new samples of
SW-1418, SW-1403 and §i7-1452? I shals be extremely grateful.

I hope you will excuse ail the troubles I
Give you, please accept my thanks and best wishes.

 

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