摘要:

Cells containing the mouse T(X;7)1Ct translocation were used to separate active and inactive X chromosomes. Cytophotometric data showed that the X(7) chromosome was at least 15% larger than any normal mouse chromosome. Cloned cell lines were established from male and female embryos with a normal karyotype and carrying the X(7) chromosome in an active or inactive state as shown by replication kinetics. As expected from the cytophotometric data, flow histograms of normal mouse chromosomes stained with 33258 Hoechst had five peaks. A sixth peak was present when the chromosomes came from mice carrying T1Ct. In this peak 6, 30 to 50% of the chomosomes were X(7) and there was almost no contamination by the normal X chromosome.

ISSN:1424-8581    

DOI:10.1159/000131569

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

Chromosomes 1, 3, 4, 15, and 16 show lateral asymmetry after replication in the presence of BrdU and staining with Giemsa at pH 10.4. Lateral asymmetry is thought to result from an unequal interstrand distribution of thymine in regions of repetitive DNA. Compound lateral asymmetry in 1 may be due to the presence of two segments of DNA differing in base composition and with different strands rich in thymine. Polymorphism for lateral asymmetry is observed in the AT-rich quinacrine-positive centromeric regions of 3 and 4, even though none of the four satellite DNAs are demonstrable by in situ hybridization there. Other workers have shown that a satellite fraction isolated using Hoechst 33258 and an EcoRl restriction fragment of human satellite DNA map on 3. There is no evidence for the presence of satellite DNA on 4. Since 20% of the DNA in the human genome reassociates at a C0t of ≤ 1 and only 4% is satellite DNA, 4 may have repetitive nonsatellite sequences; on the other hand the lack of an appropriate satellite probe may be the limiting factor. Lateral asymmetry in the Y has been demonstrated using the Hoechst method by other workers but cannot be observed with BrdU-Giemsa staining at pH 10.

ISSN:1424-8581    

DOI:10.1159/000131570

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

In human interphase nuclei containing Yq isochromosomes or two Y chromosomes, there are conspicuous somatic pairings between the brightly fluorescing Y-heterochromatin regions. These somatic pairings cannot be demonstrated in metaphases from conventional cell cultures because they are disrupted at the mitotic prophase. However, in lymphocytes cultivated in a medium containing distamycin A, the somatic pairing between Y-heterochromatin is preserved to metaphase. The present findings are compared with earlier observations of somatically paired heterochromatin. An explanation for the highly disparate frequency of somatic pairing between the Y-heterochromatin regions in Yq isochromosomes and YY chromosomes is proposed.

ISSN:1424-8581    

DOI:10.1159/000131571

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

Chromosome replication pattern was reevaluated in an unbalanced X/13 translocation carrier, 46, X, der (X), t(X;13)(q27;q12), using the BudR-acridine orange technique. The translocated chromosome, Xpter→q27::13q12→13qter, was late replicating in all analyzed cells. The autosomal segment showed a replication pattern comparable to the two normal, and presumably genetically active, chromosome 13’s, with the exception of band 13q22, which was consistently late replicating. Measurements of red-cell levels of esterase D (ESD) (a marker assigned to 13ql4) showed a 50% increase in ESD activity, compared to that in normal controls and parents of the patient. This suggests noninactivation of the ESD locus on the der(X) chromosome, a finding consistent with the late-replication

ISSN:1424-8581    

DOI:10.1159/000131572

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

Differential staining (G- and C-banding) is used to assess magnitude of chromosomal variation in eight species of African megachiropterans. These data are compared with those suggested by standard karyotypic studies, and it is concluded that in this example standard methods underestimate chromosomal variation by a factor greater than 4.5. The implication of these data is that models constructed from patterns of chromosomal evolution in standard karyotypes need to be evaluated in light of in-depth studies based on G- and C-bands.

ISSN:1424-8581    

DOI:10.1159/000131573

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

Replication patterns after 5-bromodeoxyuridine incorporation are analyzed in chromosomes of four species of the genus Cebus (C. capucinus, C. albifrons, C. appella, and C. nigrivittatus). They are compared with those of man, taking as reference the banding analyses previously described. It was found that the high degree of conservation of chromosome structures between Cebus and man was accompanied by conservation of the DNA-replication sequence of the bands. It is assumed that this conservation during the course of evolution may apply to other mammals. Thus, replication patterns may be useful for ensuring interspecific comparisons. The only detected difference concerns late-replicating X chromosomes from normal female cells: The predominant lymphocyte pattern described in man is rare in Cebus, in which the usual lymphocyte pattern corresponds to that of human fibroblasts or to the minor human lymphocyte pattern.

ISSN:1424-8581    

DOI:10.1159/000131574

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

The frequencies of cells with XY nonpairing at diakinesis/metaphase I were examined in random-bred ICR-Swiss, partly inbred DCH, and highly inbred DBA/2J and C57BL/6-bgJmice. The animals in a given inbred line displayed homogeneity in the proportion of cells with gonosomal univalents. In DBA/2J, the X and Y remained unpaired in 33.2% of the cells examined, whereas the corresponding frequency in C57BL/6-bgJ was only 7.0%. Previous data of Rapp et al. (1977) showed a low incidence of XY non-association in C57BL/6 and high frequencies in the BDF, hybrid (C57BL6 ♀ × DBA/2 ♂). We interpret our results, and the previous data of Rapp et al. (1977), to indicate the existence in mice of a genetic polymorphism for XY nonassociation. The DBA/2J strain appears to have factors that predispose to a high frequency of gonosomal unival

ISSN:1424-8581    

DOI:10.1159/000131575

出版商:S. Karger AG    

年代:1981

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000131576

出版商:S. Karger AG    

年代:1981

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000131577

出版商:S. Karger AG    

年代:1981

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000131578

出版商:S. Karger AG    

年代:1981

数据来源: Karger