ISSN:1424-8581    

DOI:10.1159/000132331

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

The gene coding for human anti-Müllerian hormone (AMH) was localized to subbands p13.2→p13.3 on chromosome 19, using in situ hybridization and Southern blot analysis of a panel of man-mouse and man-hamster somatic cell hybri

ISSN:1424-8581    

DOI:10.1159/000132332

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

The administration of alcohol to male mice 2–6 h before the preparation of second meiotic metaphases from testes resulted in an approximately six-fold increase in aneuploidy. The timing employed indicates that the observed chromosome abnormalities were a result of nondisjunction and/or anaphase lagging at the first meiotic division. A similar effect has been described in the female mouse; however, the present results suggest that the aneuploidy-inducing effect of ethanol may be substantially greater in the female than in the mal

ISSN:1424-8581    

DOI:10.1159/000132333

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

Folate-sensitive fragile sites have been demonstrated on the X chromosome of the Indian mole rat, Nesokia indica (subfamily Murinae), utilizing peripheral blood lymphocyte cultures. All normal female individuals expressed fragile sites on the constitutive heterochromatic long arm of one of their two X chromosomes (heterozygous expression); in contrast, no fragile sites were found on the single X chromosome of normal males. Preferential transmission of the maternal fragile X to the daughters is therefore suggested. Four sites have been detected so far: fra Xq1, fra Xq2, fra Xq3, and fra Xc (centromeric). It is significant that their location corresponds to the regions where constitutive heterochromatic deletions occur that result in a variety of polymorphic X chromosomes in natural populations of Nesokia. Thus there is a correlation between fragile sites, deletion sites, and karyotypic changes. In individuals that did not reproduce in the laboratory, there were more fragile sites on both X chromosomes of the females (homozygous/double heterozygous expression) and also on the X of the males (hemizygous expression). This difference in fragile site expression from the normal situation could be attributed to one or more new mutations. However, the mechanism by which fragile sites influence reproductive performance is unclear.

ISSN:1424-8581    

DOI:10.1159/000132334

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

The chromosomal localization of the gene for UDP-galactosyltransferase (glycoprotein 4-B-galactosyltransferase, EC 2.4.1.38) has been determined to be on mouse chromosome 4 by the use of mouse × hamster somatic cell hybrids. It has been proposed that galactosyltransferase is associated with the mouse T/t complex which has been localized to mouse chromosome 17. These results show that galactosyltransferase is not encoded within the T/t complex

ISSN:1424-8581    

DOI:10.1159/000132335

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

The DNase I nick translation technique has been applied to human meiotic chromosomes in situ. At metaphase I, distinct hot spots of autoradiographic labelling occur at three positions along the XY bivalent; over the Xpter and Ypter pairing tips, over Xq and Yq terminal/telomeric segments, and at a site just below the centromere in Xq. The latter might correspond to the postulated human inactivation centre. Compared with somatic chromosomes, human meiotic bivalents in general exhibit a greater accessibility to DNase I. Site-specific conformational changes in the DNA between somatic and germ line cells could be a necessary prerequisite for crossing-over.

ISSN:1424-8581    

DOI:10.1159/000132336

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

The analysis of two rodent × human somatic cell hybrids, carrying different inborn translocations of the human chromosome 14 long arm, has permitted us to narrow down the localization of the structural locus for alpha-1-antitrypsin (PI) to band 14q32.1, proximally to the highly polymorphic DNA locus D14S1 which has been localized by previous studies between 14q32.1 and 14q32.2. These data, evaluated in conjunction with other published information, suggest that the D14S1 locus is cytologically equidistant from both the PI locus and the complex locus for the immunoglobulin heavy chains (IGH) but, genetically, it appears much closer to the latter since the recombination frequency reported between the IGH complex and PI is six times greater than that between the IGH complex and D14S1 (lod score peaks respectively at 26% and 4% with narrow fiducial limits). The present report adds further strength to the frequently proposed hypothesis of a nonlinear relationship between cytologic and genetic distances of human genes. The possibility that this phenomenon may be a feature of frequent occurrence throughout the entire human genome is discussed

ISSN:1424-8581    

DOI:10.1159/000132337

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

The DNA sequence 7C22 is known to show close linkage to the cystic fibrosis locus on chromosome 7. We present a regional localisation for this sequence by in situ hybridisation to 7q31.1→q31.

ISSN:1424-8581    

DOI:10.1159/000132338

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

Aneuploidy was scored in spermatogonial stages and at both meiotic divisions in male Chinese hamsters exposed to alcohol in vivo. After light ether anesthetization, the animals were intubated (by gastric tube) with 1.5 ml of 12.5% ethanol, whereas controls were given 1.5 ml of distilled water. Gonadectomy was performed 3.5–24 h after ethanol exposure. Ethanol-dosed animals were obviously intoxicated, as evidenced by a rolling gait; serum alcohol levels in 10 animals that were tested peaked 1–2 h after exposure. Among the animals exposed to ethanol, no significant difference over time in the rates of aneuploidy was observed. These data were pooled, and, when compared to control rates, no significant difference could be attributed to ethanol exposure. The aneuploidy found could therefore be interpreted as background rates, and these compared well with data previously published for the Chinese hamster. Several artifactual phenomena were observed: Up to 15% aneuploid spermatogonial metaphases were seen in test and control animals. These were attributed to the mechanical breaking-up of closely apposed groups of diploid spermatogonia. Significant numbers of artifactual diploid MII figures and hypohaploid MI and MII figures were also recorded. To address the possibility that a spermatogonial or other long-term effect could be detected, two animals (with controls) were dosed with 12.5% ethanol daily for 13 and 16 days before sacrifice. No aneuploidy attributable to ethanol was found at MII in these animals eit

ISSN:1424-8581    

DOI:10.1159/000132339

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

Double minutes from a human tumour cell line were examined in intact metaphase spreads using scanning electron microscopy. They were discrete, acentromeric, compact spheres of chromatin fibres similar to the chromatin of the metaphase chromosomes within the same cells. They were closely associated with the telomeres and chromatids of the metaphase chromosomes.

ISSN:1424-8581    

DOI:10.1159/000132340

出版商:S. Karger AG    

年代:1987

数据来源: Karger