Experiment Station Record, Volume 93, July-December, 1945 Page: 31
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1945] GENETICS 51
action of testosterone pellets. was greater in the testis in which the implantation was
made than in the contralateral testis. m
Segmental interchange in mice, P. C. KOLLER (Genetics, 29 (1944), No. 3, pp.
247-263, illus. 5).-In three lines of mice from different males produced by irradiation
with 600-900 r. (roentgens), there was an association of four chromosomes
due to segmental interchange between two pairs of nonhomologous chromosomes.
The approximate fertility in the three lines was 30-39, 46, and 51 percent. Differences
in fertility were correlated with differences in the frequency of nondisjunctional
coorientation of chromosomes in the ring-of-four. Estimates of
fertility from cytological analysis were expected to be, in the different lines, about
24, 44, and 48 percent. Differential fertility in successive generations was attributed
either to minor structural changes or gene mutations resulting from the
radiation responsible for the segmental interchanges. Analyses are made of the
various factors responsible for genetically balanced gametes. Inherited low fertility,
common in domestic animals, may result from segmental interchange, the
maintenance of which may be favored by artificial selection.
Studies on an anophthalmic strain of mice.--IV, A second major gene for
anophthalmia, H. B. CHASE. (Univ. Ill.). (Genetics, 29 (1944), No. 3, pp. 264269).-Additional
evidence is presented that the anophthalmic strain of mice (E. S.
R., 88, p. 319) is homozygous for one major recessive factor ey-I. A mutant
female which had a normal left and medium right eye occurred in this strain. This
character was designated as Ey-2. Among 522 F2 animals, 88.7 percent had normal
eyes. The new gene appears not to be an allel of the previously reported gene
for anophthalmia, but rather an independent factor.
Inheritance of polydactylism in the fowl, D. C. WARREN. (Kans. Expt. Sta.).
(Genetics, 29 (1944), No. 3, pp. 217-231, illus. 2).-Investigations were made of
polydactyly in three strains--the usual five-toed group, a 'stock selected for
polyphalangy which appears as a five-toed stock with the No. 1 toe missing, and
the duplicate type (E..S. R., 85, p. 36). Each of the three stocks showed a distinctive
incidence of various expressions of polydactylism. These variations in
expression resulted from partial suppression of the condition due to environmental
and hereditary factors. Low temperature during the early incubation period influenced
the expression of the condition. Polydactylism is modified by varying combinations
of three processes-the addition of a digit beside the No. 1 digit, the
splitting of the added digit, and the loss of the normal No. 1 digit. Polyphalangy
resulted from the action of an incompletely dominant'modifier of the five-toed type.
The ordinary polydactylism and duplicate were each dominant mutations, probably
at the same locus. Minor modifying factors probably played a part. A considerable
body of data on polydactylism was accumulated in connection with other
genetic studies on the fowl. The variations of polydactylous stocks from different
types of polydactyly were classified and the proportions among the offspring
of different matings tabulated. Linkage relations between duplicate and other forms
of polydactyly are presented and compared with data of Hutt and Mueller (E. S. R.,
89, p. 200).
Inheritance of ragged wing in the fowl, F. B. HUTT, C. D. MUELLER, and
D. C. WARREN. (Cornell Univ. and Kans. State Col.). (Jour. Hered., 35
(1944), No. 1, pp. 27-32, illus. 2).-Independent genetic analysis showed that a
ragged wing condition of the flight feathers of Single-Comb White Leghorn and
Rhode Island Red fowls, which was not evident at hatching or even at 12 weeks
excepting in a small proportion of the adult plumage, was inherited as an autosomal
recessive. In most cases remiges were present but in others they were missing.
In the most extreme form all the remiges may be eliminated from the adult plumage.
The rectrices are unaffected. The ragged wing condition was present in
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U.S. Department of Agriculture. Agricultural Research Administration. Office of Experiment Stations. Experiment Station Record, Volume 93, July-December, 1945, book, 1947; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc5063/m1/44/: accessed April 25, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.