WASHINGTON (&

  

 

Hf UNIVERSITY

 

 

SCHOOL OF MEDICINE

SAINT LOUIS (10)
DEPARTMENT OF BACTERIOLOGY AND IMMUNOLOGY

EUCLID AVENUE AND KINGSHIGHWAY Auge 29, 1947

Dear Lederberg,

Sl and 52 Boivin are sensitive to T2, 3, 4,(6) 7 and a phage "Bordet
small" among 13 tested. The tests were done with undiluted stocks, by the method
described in Genetics 31: 620+ I recommend reading results at about 8 hours. None
of the tests distinguished between S1 and S2- All the active phages showed up
secondary colonies, so you should be able to get a number of resistant mutants without

trouble.
I gave Sol the cultures.

Our work with the r locus is in a rether uncertain state. It is
clear that no two independently arising r mutents are alikee Mixed infection with
any aux pair gives a characteristic proportion of wild type, Wexkuxm and an
aprroximately equal proportion of double mutant. If one used the proportion of
wild type as a measure of “linkage", the r mutants fsll into either one or two
linkage groups: it is not yet clear which. Other mutations can also be located

with repect to the r “man".

I would lake to hear what you find in the way of coupled trans-
formation with $1-S2.

Best wishes

A D Hershey