摘要:

A premature baby of 32 weeks gestation and weighing 1.7 kg (3 lb 12 oz), with a defect in each iris and anomalous genitalia, showed XXY triploidy on chromosome analysis. Extensive blood grouping was consistent with both digyny and diandry, but the former was more likely. Two abortuses, received as part of a survey of spontaneous abortions, revealed XXX triploidy on tissue culture. One showed a fusion defect of the neural tube; both showed late or defective fusion of the embryonic cleft of the iris. In both a small proportion of nuclei in the amnion showed two Barr bodies. In two cases in which measurements of nuclear volume were made this was about 50% greater than in diploid controls.

ISSN:1424-8581    

DOI:10.1159/000129932

出版商:S. Karger AG    

年代:1967

数据来源: Karger

摘要:

The paper describes genetic and cytological studies of mice carrying a sub-metacentric chromosome, apparently formed by the combination of a medium-sized acrocentric chromosome with a small one having a secondary constriction. The chromosome arose spontaneously in a stock of mice carrying Cattanach’s translocation and has been designated translocation T163H. Heterozygotes and homozygotes of both sexes have 39 and 38 chromosomes respectively and are phenotypically normal and fertile. The fertility of male heterozygotes is somewhat reduced, but females are fully fertile. There was a normal Mendelian segregation of the chromosome among the progeny. Cytologically, there was little evidence of instability of the chromosome, and at mitosis the long and short arm appeared equivalent in length to the tenth longest and the shortest acrocentric chromosomes respectively. At first meiotic metaphase in male heterozygotes a trivalent was recognised in all cells, and at second metaphase 98% of cells had a balanced chromosome complement with either 18 acrocentrics and a metacentric or 20 acrocentrics. Homozygous males had 19 bivalents at first meiotic metaphase, and that formed by the metacentrics was identifiable in many cells as a large ring bivalent. The translocation had a chromosome in common with translocation T138Ca, thought to be the chromosome carrying linkage group II. The chromosome provides a useful marker. The mechanism of its formation is not know

ISSN:1424-8581    

DOI:10.1159/000129933

出版商:S. Karger AG    

年代:1967

数据来源: Karger

摘要:

The duration of the periods of the cell cycle in a culture of human female fibroblasts was determined by tritiated thymidine autoradiography. The S period was 7.5 h, the G2 period was 5 h and the Gt period was 8.5 h. In all the monolayer cultures studied, only about one fourth of the cells were actively proliferating. The remaining cells were in a resting, or G0, stage. If a cell culture was exposed to tritiated thymidine for 30 min, labeled cells were in the S period and unlabeled cells were in the G2, G1 or G0 period. If exposed for 5 h, labeled cells were in the S or G2 period and unlabeled cells were in the G: or G0 period. If exposed for 13.5 h, labeled cells were in the S, G2 or G: period and unlabeled cells were in the G0 period. When the autoradiograms were exposed for only one to three days, the presence or absence of a sex chromatin body or condensed nuclear chromatin in both labeled and unlabeled cells could be determined. In this manner the status of the nuclear chromatin and the nuclear size of cells could be assessed during the various portions of the cell cycle. The following observations are based on the study of more than 12,000 XX, XXXXY and XY fibroblasts. (1) The percentage of sex chromatin positive cells did not vary significantly during any of the periods of the cell cycle. This indicated that the sex chromatin body underwent DNA replication without loss of its heterochromatic coiling and suggested that the inactive X chromosome did not become active during any specific portion of the cell cycle. (2) Non-specific condensed coiling of nuclear chromatin occurred most often in actively proliferating fibroblasts and least often in resting cells. The distinction between non-specific condensed coiling of chromatin and heterochromatin is emphasized. (3) The most significant factors which appeared to affect nuclear size were: (a) following cell division, nuclei tended to be small and have condensed chromatin; and (b) resting cells, which were presumably metabolically hypoactive, tended to have a larger nuclear size. The latter may have been the result of greater distention during fixation. When these two factors were excluded, there was no significant difference in the size of sex chromatin positive and sex chromatin negative nuclei. (4) The area of the sex chromatin body increased significantly following DNA replication, while the area of the nucleus did not. This suggested that the area of the tightly coiled sex chromatin body was closely related to its DNA content, while the area of the nucleus containing loosely coiled chromatin was more closely related to the tertiary folding of the chromatin than its DNA content. The nature of sex chromatin negative cells is discussed. It is proposed that they represent the loss of heterochromatic coiling without the loss of genetic inactivation.

ISSN:1424-8581    

DOI:10.1159/000129934

出版商:S. Karger AG    

年代:1967

数据来源: Karger

摘要:

An 11-month-old boy is described with severe developmental retardation, colobomata of both eyes, peculiar facies, syndactylies of the fingers and multiple minor malformations. Lymphocyte cultures showed the karyotype 48, XXYY, whereas, a skin fibroblast culture gave a mixture of diploid and triploid cells with the karyotypes 48, XXYY and 71,XXXYY respectively. In the triploid cell line only one of the three X chromosomes is allocyclic, as demonstrated by H3-TdR labeling and by sex chromatin studies.

ISSN:1424-8581    

DOI:10.1159/000129935

出版商:S. Karger AG    

年代:1967

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000129936

出版商:S. Karger AG    

年代:1967

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000129937

出版商:S. Karger AG    

年代:1967

数据来源: Karger