i “areh 29, 1949
“aboratoire Pasteur PARIS (V*), le ren ’ 4

Rue d’UIm, 26

 

DE

VINSTITOT DO RADIUM

TEL. : ODEON 45-75

SERVICE DE RADIOBIOLOGIE
DE . : ,
l'Institut Pastear ,
*

Dear Dr, Lederberg:

I was very glad to r ceive your interesting reprints, namely
your knkz extensive survey on bacterial genetics, but very unfor-
tunately, I lost it in a trein yesterday. If you have sore extra
ones, could you be so kind es to send me one more. I huve in my
leboratory a young fellow from Rio de Jéeneiro who vrorks on
bacterial mutations and intends to introduce this. new field in
his country next year. For this purpose, he collects the littera-
ture on the subject anc would be serateful to you if you could
send him some of your reprints, “is name is Dr.0.*.2lies, Then
you very much in acvence,

This letter sives me the onportunity of tellin=s vou « little
about my present two works, vhich ney be of sore intcrest to you,
1) Sinee 2 years, I tried ‘0 see if there is ny reletion bet-
ween corcinosenicity of some weter-soluble derivatives und their
mute renicity on bacteria, IT finelly esye to the conclusion that
so many factors are involved in both phenovena that the only
Ssisnificant results Rey involve chemicals of the same serics and
very close to cech othe some of them bcins carcinorens and the

thors not. In doing so, “ve mey expect that Pactors such as
solubility, penetretion, stedility, steric in hindrance, ete
are not too different within the sare series, and thet the diffe-
renees in activity lie in the biochemicel reeetion itself,
“A first result was obtained vith:

1,£2,5,6-dibenzanthracene-a,\* Sadkum endosaccinate

anthracene -c f encosuccinste
The former is carcinosenie and mutagenic
nor p, élthough core toxic on the becter
A secona result, more siznificant, wus re
Gurbeomaetes:

  
  

; the lattcr is not K
Le,

cently obtained with

ethyl carbemete: K +444 po tt++
Lsopropyl - ++ ++
propyl - + +
butyl - 0 0

Of course, both activities ere not mathereticelly defined, and
one could discuss the validity of my ++, but I can say that
voth ectivities run pe rellel in this series,

8) As regrrds the cancer problem, I hive been very inclined to
follow the so-celled plesmusene story, or, et least the ides
thet some senctie change in a cytoplesmic constituent vicht be
at the orisin of @ cuncer cell (this ch msc beings caneble of
modifying the nutritional recuirements or the eesll.

A path of attack seemcd to check if cercinozenic efents could

 

 

 
afk

ne

induces mut: tions in evtoplesr une Dirst in viruses
2

i oO S
Rut no clesr cut inducec mutetions hed
O a

 

never been obtained as
yet. Gince Last eneus t, T triss to induce e mutetion in a
bucterionhoce by rrad fetins “AA . infected bacteria at the
time of ph.se multiblication, Such « nut: tion hes been obtained
at nresent, As expected

u
ané the vari: t ron with the ose snpeers
a Cc

Pveor my orececine vork on the multipvlicetion of th:.t virus (T2))

  

: c.

the phenomenon varies sccording to the time of the le tent
period, since multiplication does not proecsed the sere throush-
out this nertod., Ss you mey cxpect,  tuentitetive determin tions
are pretty heré to set with s curucy, becuuse nany things
interfere, But it enceouras:s me to hundle now a sethod for

inducing mutations in a virus,
“y present purposs is to see if such mutations could not be
& ror

neu ced by a pre-treatment of the beecteovia re infection,

-T

ns the best to you

bes

“rcuse mc ror that "ovo. vardere™, “op

very sincerely

Reg nok Leng aA

Rey ih ond Later jet