a

if

/ or Th he,

Coral Le

JUL 12 1962

HARVARD UNIVERSITY . fy 3/l?
THE BIOLOGICAL LABORATORIES cogs E
16 DIVINITY AVENUE

CAMBRIDGE 38, MASSACHUSETTS
July 11, 1902

Professor Joshua Lederbere
Department of Genetics

Stanford University Medical School
Stanford, California

Dear Josh:

If all goes well I shall be on sabbatical leave in 1923-1904,
and I plan to work with Georges Cohen in Gif. My purnose will be
to study rerulatory mechanisms of photosynthesis in vhotosynthetic
bacteria, either Rhodopseudomonas spheroides or Rhodosvirillun rubrur.

 

The photosynthetic bacteria seem to be ideal material for such
an investigation since they can be cultured under a variety of con-
ditions as either heterotropns or photoautotrophs. The level of
chlorophyll synthesis can also be controlled throush licht inten-
sity and the cells can be ztrown either aerobically or anaerobically.
There is already some evidence to show that photosynthetic crowth
with acetate represses the activity of enzymes that are involved
in heterotrophic carbon metabolism. What is more, it has recently
been shown that photosynthetic growth with acetate leads to the in-
corporation of acetate into one set of intermediates when anaerobio-
Sis is obtained with hydrogen and into a different set when ritro-
“en is used. In reneral, there are several different ways in which
the organisms can be handled so as to affect their heterotrovhic or
photoautotrophic growth. No one has, at least to my knowledze,
looked at control mechanisms concerned with photosynthesis, and
both Georges and I are intrigued by what may develop.

diet au 137

Having written this lone discourse, I now come to the purpose
of my letter. TI am apnlvine for fellowshivs to both the N. S. Ff,
and N. I. H. and would like to know if TI can impose upon you for
letters of recommendation. I hope to have letters from three people
outside of this department and particularly from one or two with
whom I have had some contact for several years.

Best regards from Elizabeth and myself,
Sincerely,

f
eY

_ R. P. Levine
Associate Professor
of Biolory

RPL / JAS