摘要:

Sixteen triploid and one tetraploid human abortuses were studied for the origin of polyploidy using a sequential Q- and R-banding technique. Ten triploid abortuses provided informative data: one originated in the maternal first meiotic division; five apparently resulted from dispermy; two derived from an error during either the paternal second meiotic division or the first mitotic division; and the last two were of paternal origin. The results indicate that paternal factors, especially dispermy, are the predominant sources of triploidy in man. The tetraploid abortus showed duplication of both the maternal and paternal haploid sets, suggesting normal division of chromosomes and suppression of cytoplasmic cleavage at the first mitotic division. No correlation was found between the origin of polyploidy and the phenotype of the triploid abortuses, nor between the origin of polyploidy and the maternal use of oral contraceptives.

ISSN:1424-8581    

DOI:10.1159/000130756

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

The X chromosome of the male pronghorn (Antilocapra americana) is larger than the “original” type and carries a large segment of late-labelling chromatin. The Y chromosome has a late-labelling segment that appears to duplicate synchronously with that of the X. Both chromosomes have segments that label throughout the period of observation; that of the X is about 4.7 % of the haploid complement and approaches “original” proportions. The X chromosomes of the Rocky Mountain goat (Oreamnos americanus) appear to be of the “original” type, without marked late-labelling regions, and the Y chromosome is small. The structure and origin of extra-large sex chromosomes ar

ISSN:1424-8581    

DOI:10.1159/000130757

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

A human-mouse hybrid, DUR 4 (Solomon et al., 1976), containing a human X/15 translocation chromosome and also chromosome 5, among other human chromosomes, was used in a double selection system to obtain hybrids of four different types: X/15+ 5+, X/15– 5+, X/15+ 5, and X/15– 5–. Standard positive and negative selection systems were used for the X chromosome, and negative selection for chromosome 5 was done with diphtheria toxin. The assignment of HEXB and the diphtheria toxin sensitivity gene to chromosome 5 was confirmed. HEXA was present only when both the X/15 chromosome and chromosome 5 were present. A “HEXA-like” band segregated with chromosome 15 (or X/15) but independently of chromosome 5. This component, unlike HEXA, does not contain human HEXβ

ISSN:1424-8581    

DOI:10.1159/000130758

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

Supernumerary chromosomes have been examined in 352 black rats, covering three geographic variants, by use of conventional and C-band staining techniques. Metacentric supernumerary chromosomes, one to three in number, were found in Malayan black rats (Rattus rattus diardíi), with 2n = 42, in Indian black rats (R. rattus rufescens), with 2n = 38, and in Ceylonese black rats (R. rattus diardii), with 2n = 40. The supernumeraries had similar morphology and stained heavily along their entire length by C-band staining. These findings suggested that the supernumeraries had originally developed in the Asian-type black rats and then were sequentially transmitted to the Ceylonese and Oceanian-type black rats, probably in southwestern Asia. A subtelocentric supernumerary chromosome found in one Japanese black rat seemed to have developed independently from the above metacentric supernumeraries

ISSN:1424-8581    

DOI:10.1159/000130759

出版商:S. Karger AG    

年代:1977

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000130760

出版商:S. Karger AG    

年代:1977

数据来源: Karger