BIOLOGY AND MEDICINE
an effort to determine the extent to which strontium 90 is likely to be ingested by the human
population. Samples have been obtained thus far from the Philippines and Turkey, and a team
in Libya will collect samples from that country. Plans were under way to expand the program
into a number of Latin American countries, and initial contacts were made with officials concerned with nutrition. An AEC representative will visit these Latin American countries during
the summer of 1957 to discuss the program and enlist needed participation,
MOUSE GENETICS
DOE ARCHIV.-
A conference on mouse genetics sponsored by the British Medical Research Council was
held at Harwell on April 26 to ensure that similar studies of radiation-induced mutations at
specific loci in mice being carried out by the United Kingdom and the United States do not
overlap but complement one another. The conference was attended by the principal geneticists
of the Harwell project and three geneticists prominent in the AEC program.
The results of studies made at the Oak Ridge National Laboratory by Russell and at Har-
well by Carter were compared, andthe following significant statistics reported:
Number of
Investigator
Carter (U.K.)
Exposure
(roentgens)
Mutations
Russell (U.S.)
0
164,687
63,116
4
7
6.0
Combined
Carter (U.K.)
0
37.5
227,803
34,998
ii
4
6.9
16.3
Russell (U.S.)
Russell (U.S.)
Russell (U.S.)
0
Mice
Mutation
rate per
locus
(x 107°)
300
600
1,000
37,189
72,472
31,816
23
5
21
Induced
mutations
per locus
per roentgen
(x 1078)
9.1
-
-
25.7
88.3
147.9
94.3
27.1
23.5
8.7
NOTE: The apparent drop in the induced mutation rate when the exposure is increased from
600 to 1,000 roentgens is caused by a substantial increase in the death rate at the higher exposure.
The technique used in both the Carter and Russell studies is based on (1) the fact that most
mutations are recessive, that is, they must be inherited from both parents to produce a visible
effect on the individual, and (2) a “specific locus” test, which was devised to detect such re-
cessive mutations in offspring.
A stock of mice was built up to be pure recessive for seven different mutant genes, each
one producing a visible characteristic such as short ears, dilute hair color, or white spotting.
Females of this stock were mated to males with all normal genes but which had been irradiated
(or not irradiated in the control series), In the resulting offspring a recessive trait of the
mother appeared only if there had been a mutation of exactly the samekind in the father’s
(
3
U~
germ cells (i.e., at the same locus in the chromosome) as that responsible for the trait in the
mother.
37