Moveaber &, 1948.
Dr. D. Lewis, | : , .

- dobn Innes Horticultural Institation, | Ny
Mostyn Road, Merton Pk.» (wos
London SW 19, England. , ~ eR

‘Thank you for your note of 25 Oct. As you might imagine, { have also been
much inpressed with the parallelisa of technique ‘and philosophy that pertains
to the genetics of microbes and of pollen. Indeed, I was strongly teapted to
included a discussion of the male gametophyte and of tissue cultures in ay
recent review, under the general heading of "cellular genetics." It has seemed
to me that if the problem of the continued propagation of the gametophytes of
higher plants would be solved, that one would have the best material imaginable

for physiological genetic studies. Wp :
Ls baline? ,
My attempts to find qualitative of gene functions in bacteria

have not yet been successful. The most promising material has consisted of cer-

tain mutations which affect the production of several ensymes (e.g. glucozymase,
maltase and lactase) at once, but attempts to find alleles ig which some of these
functions are represented have generally resulted in "suppressor" mitations at other
loot. By looking for mtational losses, in turn, in these suppressor stocks, however,
we hope to gain some Ankling of the previous functions of these "suppressor" loci.
However, an allele of one of the mtants has been found which is temperature sen-
sitive, and which shows a distinct temperature threshold for its several effects

and this might be regarded as a splitting of the specificities of the gene. In general
the genetic determination of enzyme specifities has turned out to be far more Com
plex than I would have imagined a priori from the one-to-one generalization.
 

 

 

 

 

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2 shall be glad to send you the reprints you asked for as soon as

I receive the set of ay review in Heredity, and look forward to a con
~ $demed exchange of our ideas and pubjications. ,

Yours sincerely,

Joshua Lederberg
Assistant. Profesecr of Genetics.

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