Deere

VANDERBILT UNIVERSITY
NASHVILLE 4, TENNESSEE :

DEPARTMENT OF BIOLOGY

Nov,25, 1945

Joshua Lederberg, A/S, V-12, U.S,N.R.
c/o Dr. Francis J. Ryan, —
Dept. of Zoology,

Columbia University,

New York 27, N. Y.-

Dear Mr. Lederberg:

You wrote recently asking about anelyses of Neursopore
mycelium. I have assayed only two samples, one of wild type
( no. 1-A), and the other of no. 35304-A. The latter is
a lysineless mutant at temperatures above 29° but at Lower
‘temperatures it regularly adépts to growing without lysine.
The wild type mycelium was prepared as follows: grown with
aeration in carboy, filtered off on a Buchner funnel, washed
with distilled water and again filtered off, then dried
at 85-959 after wringing as dry as possible in cheesecloth.
This was hydrolysed by refluxing 24 ors. with HCL and most
of the acid was removed by distilling of. under vacuum, ashe
remaining acid neutrelized wita KOH.

Tne wyceiium of 35304 was pre,»area in the same manner. lt

was grown in the absence of extreceilular lysine at 25°, 2.25
Results on wild type mycelium gave, in two trials, 2.25% lysine Yé
and 2.46% lysine. Assays of 35304 gave 2.53% lysine and 2.52% d.
lysine. L.7%
. ~
LA 2
The only other information which might be of interest to 5 ——

youreoncerns the relative amounts of growth obtained from

a given amount of lysine by otner lysineless mutants, These
results are selected from tests with 28 lysineless mutants.

Each mutant was tested at five concentrations of lysine, using

one flask at each lysine level except at the Llevek of U.876

mg lysine per culture. Here duplicates were used. All were tested
simultaneously. The curves were drawn, and from these tue amoummt
of growth (in mg. dry weight) from 0,876 mg. of Lysine is wiven
beliw. This was retested on anotaer occasion witn a smaller number
of strains and stiown to be reproducible within reasonable Limits.

Strain no. 4545 ----= 46.lmg. dry weight

Strain no. 235944 ---- 35.0 mg. dry weight
Strain no, 37101 ---- 27.7 mg. dry weight
Strain no. 39707 - -- 48.2 mg. dry weight.
; a

From tnese results there ap ears to be considerable
difference in the efiiciency of lysine utilization in tae difierent
lysineless strains. Incidentally, from otaer evidence, tnertirst
three strains appear to be of different jzenetic types. No. 59707
has not been tested for its genetic type.

Il hope tnis information will be ot use to you. I] suall
send you a reprint wnen toney arrive nere.

Sincerely yours,

ON tera

A. H. Doermann