UNIVERSITYOFCALIFORNIA

.OGY

Dr. Joshua Lederberg
Department of Genetics
University of \iisconsin
liriadison, Wisconsin

Dear Dr. Lederberg,

December 15, 1949

     I m a!?-plging for a, Eational Research Cou_zlcil Fellowship in        : ,,;:
the Natural ScienBes and for an iisllericen Cancer Society Fellovrship,      , ,:!
in the hope that I xmy be succesful in obtaining one of these. I would : -:+('
like very much to use this fellowship to work
the period from Sept&mber 1950 to June 1951.  in your laboratory during '.- 1,

                                                                           .,

     I will receive my Ph.D. in Bacteriology at the University of    "'-I
California in June of 1950. I have been trorking under the directorship
of Dr. R.Y. Stanier principally,  and. also rrLth the aid of h-s. M,        ~ 8,'
                                                                           .<
Doudoroff and H. Barker. I have held the position of Teachil?-~; dssist;ant :'j'?
in Bacteriology at this university for two years and nos-r hold a Research ,; .
Assistantshi>.  For the gnst coql& of years I have beea investigating   +,'
the phenomenon of mtation in P seudo~~oms fluorescens, the nreliminary   ' Ij '-.k
work having beevl published in the Jourizal of Bacteriolo@a, vol. 58,           j
                                                                           ,:
71, 1949+                                                                           . c
     The following will give you some idea of ny recent y*Tork, and        / 8
will indicate to you my fields of intez%est:                                            
                                                                           '. I

      1. If one considers the Imtation to the utilization of itaconate ..
as a new mutation or a back Fmtation, it would be possible by continued   (j"
selection of further mtations, to build a new catabolic pathway or   ;.::
at least uncover a lost catabolic process once possessed by the                s'
Pseudomonas. In addition, if this ap;jroach z>roved at all successful,       i
o?e would have outlined the pathway of oxidative ~~etabo1i.m of some
compound X and have deraonstmted the feasibility of usihg this ap-groaeh
in the study of intemlediary pletabolis??.  This approach has been somewhat :
successful and I am now in the process of investigating the relationship
between :le;$conic acid (M) and
m..lt3~ts:    , 1-k EAt .    itaconic acid (I) by use of the following :::.

     2, On the basis of your theory of the economy of genes, it       ' :
was thought that if the mutation to the utilization of itaconate is a
novel function for a locus, a simultaneous loss of a ::lore 7)riilitive        ',>r
function would have been evoked. %ith this in mind, together -r;.rith the '
purpose of discovering the enzymatic nature of the itaconate rlutation,
metabolic studies of the itaconate mutant ?i':ere under-i;aken.  It -Pas         
found by the method of simultaneous adaptation that the :ilutation to
use itaconate results in a fundamental change in acetate metabolism.
ks a tool to the further study of itaconute utilization, use was made         :
Of a Slow oxidizing mesaconate mutant which does not oxidize itaconate
when this compound is present alone.  Itaconate inhibits the 0xMatlon
of mesabontife ,a&-ace-t&&, Tbnt7doBs hot-:--fnhibit the oZidation M?F              ,

stroofnate;.~p.f~~~att;B~. `:-- Ih:"laotej An the..yresenDe-of:'a&y of .the abovW I-
mentioned dicarboxylic acids, itaconate itself is oxidized,   The


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i*                                   2.

- T.   UNIVERSITY OF CALIFORNIA

\ i.aBPARTMENT OF BACTERIOLOGY
BERKELEY 4, CALIFORNIA

wild tyne is not inhibited by itaconate, nor is it used in the -0resence
of succinate, fwlerate or malate.. The exact nature of this phenomenon
requires further investigation.

    To further elucidate the mechanism of muta"i,ion, che:lical
mutagenesis was attempted.  In order to explain the occurrence of
spontaneous mutation, a chemical was sought that occurs naturally,
one that has been shown to be an intermediary netabolite, as v:ell as
having been implicated as a mutagen.  ForAlaldehyde met these requirements.
Experiments have definitely showy that formaldehyde is a mutagenic agent
of a high order, and is characterized by a large degree of sneciBi.city.
Formaldehyde induces an absolute increase of itaconate mutants in a
resting -population.  Attempts to study the kinetics of the phenomena
have so far resulted in failure, due to the reactivation of forllaldehyde-
deactivated cells by unknown components in the media. Formaldehyde
will not induce mutation to streptomycin resistance in the Pseudomonas
nor will it induce mutation of E, coli to phage resist,ance.  The naturi
of the reactivation prosess should be investigated and this may shed
some light on the specificity of formaldehyde as a mutagenic agent.

    I am interested in continuing these studies along lines which
we could mutually decide upon.  Of course, if you have some investigation
under way or being contemplated that you would rather have me work on,
I would be very Sappy to collaborate with you in such an undertaking.

    I realize that the information given here is rather limited
due to the shortage of time, but I hope hhat it is sufficient to enable
you to make a favorable decision. If your decision is to accept me,
would you please send me two letters,
Research Council                one addressed to the Matdonal
Cancer Society,   Washington D.C   and the other to the'ti2erica.n
      6ommittee on'Grov&, National Research Council
Washington, D.C., stating that.space is available for me at yo&
laborato-ry and that you will act as my scientific advisor.

    I would appreciate it very much if you would send me these
letters as soon as possible,
January 1, 1950.        since I must turn in the applications by

k....." . .