摘要:

Minute deletions of the B-group short arm have been demonstrated in five of six cases with clinical features suggestive of a deletion of chromosome 4 or 5, but with grossly normal chromosomes. A deletion as small as 8% of the short arm was detectable by each of five observers when randomly arranged cells from controls, cases with large deletions and the cases with suspected minute deletions were scored blindly for the presence of a deletion. Another two cases were shown to have deletions of only 4% of the short arm by measurement studies, although the deletion in these cases could not be detected visually in the blind study. The presence of the deletion was confirmed in one case by DNA-labelling studies showing that the putative deleted chromosome consistently had the replication pattern of chromosome 4. In another two cases measurement of the long arm confirmed that the deleted chromosome was a chromosome 5.

ISSN:1424-8581    

DOI:10.1159/000130027

出版商:S. Karger AG    

年代:1969

数据来源: Karger

摘要:

Measurement of the B-group short arms from 25 cases and five balanced carriers with a Bp– chromosome showed a significant clustering of the size of the deleted short arm between 0.45 and 0.65 of the normal short-arm length. No differences in length were apparent among family members when the deletion was familial. The distribution of deletion size appeared similar for chromosome 4 and chromosome 5. No correlation was found between any clinical feature and the length of the deleted short arm. The results are discussed in relation to the origin of deletions – simple terminal or interstitial deletions or reciprocal translocati

ISSN:1424-8581    

DOI:10.1159/000130028

出版商:S. Karger AG    

年代:1969

数据来源: Karger

摘要:

Leukocytes from 17 A-bomb-exposed survivors and 10 control persons of the same age group were cultured for two and three days. Among the controls, aberrations other than single or isochromatid lesions were seen in 0.6 % of cells at two days of culture and in 0.8% of cells at three days of culture. Among the exposed, 7.0% of cells cultured for two days had these aberrations, which were seen in 8.7% of cells cultured for three days. Six cytogenetically aberrant clones were found in 5 of the 17 exposed survivors. Four of these were detectable on the basis of the two-day culture results alone. Since our previous studies of 171 heavily exposed survivors, using the 66 to 70 h culture time, had enabled us to detect only four clone-formers, it appears that the shorter culture time enhances clone detection.

ISSN:1424-8581    

DOI:10.1159/000130034

出版商:S. Karger AG    

年代:1969

数据来源: Karger

摘要:

In vitro studies were carried out on kidney epithelial cells and fibroblasts of female Microtus agrestis and fibroblasts of male and female Cricetulus griseus. By means of pulse labeling with tritiated thymidine, the duration of DNA synthesis within the S period of the cell cycle was determined for the autosomal ‘euchromatic’ portions of the chromosome complements, for the large and well-defined, structurally heterochromatic segments and for the active and the ‘Lyon-ized’, inactive X portions in the females. (Both species possess composite-type X chromosomes.) Strikingly similar results were found in both species and both types of tissues studied. In partially overlapping sequences DNA synthesis starts first in the autosomal euchromatin and in the active X, later in the inactive X and finally in the structural heterochromatin; it ends in the same order. “While DNA replication in given euchromatic segments takes nearly four hours, it requires less than two hours in the structurally heterochromatic segments. Interestingly, DNA replication was found to take considerably longer in the active than in the inactive X. This indicates that in the functional X chromosomes the rate of DNA synthesis is not dependent on the number of replicons (which must be assumed to be identical) but is accelerated in the genetically inactivated X c

ISSN:1424-8581    

DOI:10.1159/000130029

出版商:S. Karger AG    

年代:1969

数据来源: Karger

摘要:

Acute and chronic studies of male and female meiosis in an Imperial-Chemical-Industries-derived strain of mice were carried out with LSD-25. Over a wide range of doses claimed to be effective in teratogenesis and male meiosis in the mouse and in the production of chromosome damage in leucocyte cultures of human blood, no convincing effect was detected on the chromosomes of first or second meiotic divisions, nor in those of the bone-marrow or of the few spermatogonial metaphases that were studied.

ISSN:1424-8581    

DOI:10.1159/000130030

出版商:S. Karger AG    

年代:1969

数据来源: Karger

摘要:

A previously unreported type of male pseudohermaphrodite sheep is described. The animal had XY sex chromosomes in all tissues studied and was chromatin negative. It had female external genitalia and undescended testicular gonads, with an histology distinct from that of previously reported sheep intersexes. Its origin could not be explained on the same basis as the more commonly reported female (XX) intersexes seen in man and other domestic animals. Comparison, however, of this sheep with the ovine cryptorchid suggests that the germ-cell aplasia seen in the latter is genetically determined and due to a possible gene locus or loci deletion of the Y chromosome.

ISSN:1424-8581    

DOI:10.1159/000130031

出版商:S. Karger AG    

年代:1969

数据来源: Karger

摘要:

Quantitative study has been carried out of the conditions under which exposure of Chinese hamster cells to Colcemid produces polyploidy, chromosomal aneuploidy and cell killing. Single cell survival curves indicate that survival decreases with increasing exposure time and drug concentration. However, for exposure periods of 24 to 48 hours and drug concentrations in the neighborhood of 0.05 to 0.9 µg/ml, a plateau is reached at 20 to 50% survival. No appreciable change in chromosome counts occurs at or below 0.01 µg/ml. At 0.015 µg/ml, counts indicative of nondisjunction appear and increase, reaching a maximum at 0.02 µg/ml. From 0.03 to 0.07 µg/ml, approximately 80% of the cells are tetraploidized. A variety of clones with additional chromosomes can be obtained which may be useful for genetic-biochemical studies. Chromosome losses are also produced, but under the conditions employed here, these were generally inviable. The system appears to lend itself to screening of various agents for their ability to produce changes in chromosome number in mammalian cells in vitro

ISSN:1424-8581    

DOI:10.1159/000130032

出版商:S. Karger AG    

年代:1969

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000130033

出版商:S. Karger AG    

年代:1969

数据来源: Karger