Bacteriology Department,
University of Melbourne,
Carltegigi’No3e,  .
Victoria . Australia.

 

10th December,. 19540
rm 8

Dr. J. Lederberg,
Department of Gentics,
Universityof Wisconsin,
Madison 6,

WISCONSIN . U.S,A.

  

Dear Josh and Esther,

I have been so’terrifically busy during the last
few weeks that I have not had timé ‘to buy conventional Xms cards for Be
friends abroad. Please accept this hurried note as a carrier of greetings”
from us to youl ee

We are continuing on with the yeast work and have
been attempting to prepare auxotroph donor strains for restoration
experiments. So far we heve concentrated on WY25 (Ephrussi's norm)
and have reached the following conclusions: .

 
    

1. The mting type te A. Re “Bee a
20 UV. irradiation yields about. petites among the survivors and
, of these something less than 10% are auxotrophs. | Se
-2e Of the normal survivors nomare auxotrophic. . 6
4. 4 preliminary conclusion from these.irrediations ‘is that.itis.- .
_ _ dmpossible to produce an ‘auxotrophic yeast which is not deficient.
in cytochromes. Or to put it another wy 411 auxotrophs are
petites, but not all petites are auxotrophs, .

 

&

It is quite probable that our U.Va petites are
segregational types (nuclear gene damage) and this we would like to
prove by crossing with alpm Sopetative petites. I was wondering
whether you could send me by air,and clarge to us the freight, some
of Caroline Raut's haploids of known mting type so that we can
extend these observations on petite induction by U.V. and their nature
on & wide range of yeast. These findings you will appreciate tie
up with my examination of the auxotrophs examined in Madison which
were clearly either petites or partial petites. As far as I know
neither Ephrussi nor anybody else has linked auxotrophig and petiteness
and I thought we might clear up this unexpected observation while
proceeding towards our min problem. /

You will remember that in my letter to you of 15th
July I did formate a plan necessitating the ‘use of-marked donor cells.
 

fee SiG RT ETE:

Tn the “Light ‘of the: -prssisint: ‘Atntorebdes with’ Ue “thie S08. “hive 6 be.
médified, We hope also-t¢ séé ‘the “effect “of ‘X-ray and nitrogen’ ‘mestand
ae inducers‘ of ‘pétitenesd and autotrophie. ‘Any ‘comments you" would “like

. tetas * “on _bhese Préposats: “€nd ndings would “be greatly ° ‘appreciated o

 

“With best yighes: for’ wins “an the New Yéar fion EDen
and myself.

  

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