abstracts of papers presented at the 1962 meetings - Genetics

ABSTRACTS 939
ARAKAKI, DAVID T., (Introduced by JIMMIE B. SMITH), Genetics Department, University of
Hawaii, Honolulu 14, Hawaii: Chromosomal analysis of normal and mongoloid individuals of
uarious ethnic groups in Hawmi.-The chromosomal patterns of 32 normal persons were examined
by the leukocyte culture technique. Normal samples represented seven different ethnic
groups: Japanese, Chinese, Caucasian, Hawaiian, Korean, Filipino, and Negro. The modal number
of 46 was found to characterize the chromosomal complements of these seven ethnic groups,
of which, the Korean, Hawaiian, and Filipino groups represented original chromosomal analyses.
In addition, normal karyograms from the first four ethnic groups indicated that no significant
morphological difference existed among them.-Chromosomal patterns of 13 mongoloid idiots
were examined by the same technique. The modal number for each of these patients was 47, presumably
of the trisomic-21 type. Analyses of the chromosomal pattern in several Caucasian,
Japanese, and Hawaiian patients clearly indicated a chromosome number of 47 with trisomy for
chromosome 21.
BACON, D. F., Institute of Microbiology, Rutgers, The State University, New Brunswick,
N. J.: Sexual transfer of the Hfr property from the K-12 strain to the W strain of Escherichia
coli.-Matings of F+ cultures of strain K-12 with auxotrophs of strain W yield recombinants with
very low frequency. Several Hfr cultures of K-12, however, produce recombinants with W at
high frequency; in three such cases the Hfr property was transferred to the W recipient, and
could be recovered after repeated backcrossings into W. The system studied in greatest detail involved
culture 808 (K-12, Hfr), kindly supplied by DR. F. JACOB; this culture was crossed with
a proline auxotroph (pro-) of W and pro+ recombinants were screened for their ability to transfer
leucine independence (leu+) with high frequency. The kinetics of gene transfer were studied
with the aid of a blendor and with phage T6. In the cross, K-12, Hfr 808 x K-12, leu-, the
leucine marker entered at 6.5 minutes and the maximum number of recombinants was equivalent
to 10% of the Hfr cells; in the crosses, K-12, Hfr 808 x W, leu- and W, Hfr 808 X W,
leu-, the leucine marker also entered at 6.5 minutes, but the maximum recovery of recombinants
was 1-2% of the Hfr cells; in the cross W, Hfr 808 x K-12, leu-, recombinants occurred with
low frequency (less than 0.001% of Hfr cells). (Aided by the U. S. Public Health Service and
the Office of Naval Research.)
BAILEY, D. W., Cancer Research Institute, University of California Medical Center, San
Francisco, California: Histoincompatibility associated with the X chromosome in mice.-During
an experiment on induced mutations at the histocompatibility loci, evidence was fortuitously
obtained for the existence of an unanticipated source of histoincompatibility.--Grafts were exchanged
between hybrid types in like-sexed groups by means of a tail-skin grafting technique
(BAILEY and USAMA, Transplantation Bull. 7: 424, 1960). Out of 36 grafts transplanted in
males from (BALB/c 9 x C57BL/6 8 )F1 to (C57BL/6 9 x BALB/c 8 )F1 hybrids, 31 survived
to five weeks after grafting; 14 to nine weeks. Out of 34 grafts made in the opposite direction
in males, 16 survived to five weeks after grafting; none, to nine weeks. In contrast, all 80
grafts exchanged between reciprocal hybrids in females survived to nine weeks and beyond.-
Second-set grafts on five F, males were rejected in an average of ten days, suggesting that the
phenomenon under observation was immunological in nature. In order to determine the relative
roles played by the X and Y chromosomes, nine other sensitized F, males were challenged with
grafts from both parental strains. In all cases it was the skin of the paternal strain that was rejected.
Moreover, mean survival time of these paternal-strain grafts was similar to that of
second-set grafts. It is therefore concluded that the X chromosome is the bearer of one or more
histocompatibility determining factors. (Supported by U. S. Atomic Energy Commission, contract
AT(l1-1)-34, Proj. No. 41.)
BAKER, L. H., and N. J. BECK, Hy-Line Poultry Farms, Johnston, Iowa: Genetic sampling
uariation in tester female populations of poultry.-While a recurrent to tester selection program