Experiment Station Record, Volume 92, January-June, 1945 Page: 8
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~8 ~EXPERIMENT STATION RECORD [Vol. 92
differed from materials of animate origin, suggesting that viruses may be inanimate.
Improvements in the Lactobacillus casei assay for biotin, G. M. SHULL and
W. H. PETERSON. (Wis. Expt. Sta.) (Jour. Biol. Chem., 151 (1943), No. 1, pp.
201-202).-A yeast supplement, adequate in the eluate factor of Hutchings et al.
(E. S. R., 88, p. 175) but very low in biotin, for use in the basic medium for determining
biotin by the L. casei method of Shull et al. (E. S. R., 87, p. 626) was prepared
by a method described. This involved a modified elution procedure for
removing most of the adsorbed eluate factor from the norit without eluting the
adsorbed biotin. Another modification presented involved the prepartion of an
inoculum which was independent of the drop size.
A microbiological method for the determination of choline by use of a mutant
of Neurospora, N.H. HOROWITz and G. W. BEADLE (Jour. Biol. C hem., 150
(1943), No. 2, pp. 325-333, illus. 2).-A mutant strain of N. crassa, produced by
ultraviolet irradiation of the wild type, was used as the test organism since it was
found to be able to grow in a medium containing only salts (including certain
trace elements), sugar, biotin, and choline, with growth response proportional to the
amount of choline present up to the limit of about 40-50 Ig. per 25 cc. of medium,
and with failure of growth in the absence of choline. Of more than 40 compounds
tested, only choline, lecithin, and methionine were found to support growth of the
mutant. In analytical practice, choline was liberated from any lecithin present in
the sample by preliminary hydrolysis accomplished by autoclaving the sample with
3 percent H2SO4 for 2 hr. at 15 lb. pressure. Following neutralization with
Ba(OH)2, the solution was treated with permutite, in order to separate the choline
from the methionine, and the choline then eluted with 5 percent NaCl. The eluate,
properly diluted to give final choline concentrations between 0.5y and 20y per 25 cc.,
was distributed among 250 cc. Erlenmeyer flasks and made up to 25 cc. with basal
medium (containing no choline). After autoclaving and cooling, each flask was
inoculated with a drop of spore suspension and incubated at 25 C. for 3 days, at
the end of which time the pads were removed, pressed out on filter paper, dried
at 900, and weighed. Choline values were calculated from a plot of a standard
series made up to contain Oy-20y per flask, and run anew with each new spores suspension
used. Choline values determined on different amounts of the same solution
generally agreed within 10 percent, and recoveries of added choline ranged from
90 to 110 percent of theoretical. Data are reported on the choline content of a
number of natural products.
The chemical determination of thiamine and cocarboxylase in biological material,
B. ALEXANDER (Jour. Biol. Chem., 151 (1943), No. 2, pp. 455-465).-Dilute
hydrochloric acid extracts of animal tissues (dog liver, kidney, muscle) and cereals,
and water extracts of feces, were analyzed for thiamine by the procedure utilizing
the Prebluda-McCollum reaction as previously developed for urine (E. S. R., 90,
p. 12). By simultaneously measuring the free and total thiamine in aliquots of
the same material, a value for the phosphorlylated or cocarboxylase fraction was
also obtained. Enzyme hydrolysis was utilized to liberate the thiamine from the
cocarboxylase, while in the analysis for free thiamine care was taken to destroy
naturally occurring phosphatases which might, by splitting cocarboxylase before
analysis, give erroneously high values for free thiamine. Only very small amounts
of free thiamine, representing but a small portion of the total thiamine, were found
in animal tissue. The concentration of total thiamine and cocarboxylase in the
tissues of the dogs used in the study were found to be increased somewhat by the
intramuscular injection of thiamine hydrochloride in amounts of 2.0 mg. per kilo.
Significant amounts of thiamine were found in human feces, and the amounts were
increased somewhat by the oral or parenteral administration of thiamine. The
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U.S. Department of Agriculture. Agricultural Research Administration. Office of Experiment Stations. Experiment Station Record, Volume 92, January-June, 1945, book, 1947; Washington D.C.. (digital.library.unt.edu/ark:/67531/metadc5064/m1/21/: accessed April 26, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.