UNIVERSIDAD DE CHILE Kebionien

ESCUELA DE MEDICINA '

INSTITUTO DE QUIMICA
FISIOLOGICA Y PATOLOGICA

Borgofio 1470 - Santiago

April 15, 1958

Dr. Joshua Lederberg
Department of Genetics
University of Wisconsin
Madison 5, Wiscongin

Dear Josh:

Thanks for your letter anda bunch of reprints you sent me.
It seems we have finally got rid of that ms because I haven't heard from
the Editor and Bernie told me he gave it his blessings although he still
thinks it is hard to read,

Perhaps my letter was misleading in the sense that I never
reacted badly to Bernie's criticigm. I think that practically all of
them were very justified. Of course, it bothered me to have to correct
the ms (I hate ali office worl:, yo: lmow), but It improved quite a lot
thanks to Bernie in spite of the fact that he still doesn't understand
my way of conductins the research.

I don't know if you read the final copy of the ns, but
I followed your advise and let the hammer fall on Monod's theories with
all its weight.

I plan to continue on the permease story and as a matter
of fact I have thought of making active transport my main Line of research.
It is a rathor virgin field 4n‘which the microbiologist is just peering in.
It's amazing that I have decided this after being sort of drag into the
field (I must confess that I never liked too much the activation problem).

Your comment on the Lac”, ability to ferment galactose
interest me very much, Of course it will be nice to have the Lac*Gal™
which lacks galactokinase, and the Lac”, Gel”. Please send them to my
name with only Borgefio 1470 ag the address because it avoids a lot of red
tape. Last time it took me six weeks to cot the strains from the Post
Offica.

How are you coming along with the transduction with DNA
Chareaff style? Please let me know about it because if it doesn't work
it might be still profitable to continue with the labeled DNA experiment.
I have ffhow two strains of E. coli thymine-defficient and labeled thymine
therafore I could de the experiments rather easily with all the experience
I have accumulated with P32 labelling.

About my experiments: A package with radioactive galactose
to make C-14 labeled TMG got lost in the mail and therefore I have to wmit
until a few more weeks to obtain more. In the mean time I have played around
with the masking factor of protoplasts. The stability of protoplasts
becomes a different problem if one examines the leaking of beta-galactosidase.
The problem has not been solved because sucrose, which is the best stabilizing
agent inhibits quite a bit the beta-galactosidase at the concentrations usefle
. svc’ ths &
Le arners = vaca 2

Other stabilizing agents reported in literature have failed to stop the
release of enzyme from the protoplasts. The protoplasts were prepared
either by your method or by Fraser-Mahler's, If you have any comment

on this it will be appreciated. If worse come$to worse I plen to compare
the accumulation of TMG and. the ONPG hydrolysis in protoplasts susrended
in buffer with 10 53 sucrose.

There is another point related with protoplasts whieh I woula
like to submit to your opinion. There ig a man heve in Chile, afood friend
of mine too, whachas done a very excelent work on cytology of nerve fibers.
I think he has been able to muke the thinest sections knovm in electron
microscopy. A few days ago talking about protoplasts I suggested to him
the idea to study sections of srotoplasts to compare them with sectiong of
bacteria to see which part,if any, is actually removed by the lysozyme
or the penicillin treatment. I was wandering if this work has been done.
Do you know anything along this line? Most of the pwople believe that
lysozyme eliminates the coll wall of bacteria when really if the lysozyme
dissolves a rigid frame of the cell wall leaving most of its constituents
intact the same result would be expected. The electron microscope could
discriminate between the two hypothesés if sections are used. The first
hypothesis is supported by the fact that Iysozyme dissolves preparations
of cell walls, but one wonders what is a "preparation of call walls".

‘rom your mg I found most interesting the formation of
protoplasts from DAP requiring cells. Have you another mutants in the
biosynthetic pathway of the cell wall? The approach seams quite locical now
and I hope it pays up.

Don't worry about my visiting Madison on August. I lmow
better than that. My plans so far are to leave Chile sround the end of
August and spend two or three months at Bernie's laboratory (if I can
finance it). After that period I will make a tour through the Middle
West and then back to Chile,

Best regards to you and Ssther from Raquel and I,

a
~- *

yours,

Peuo