摘要:

Chinese hamster X mouse somatic cell hybrids segregating mouse chromosomes were examined for their mouse chromosome content using trypsin-Giemsa (GTG) banding and Hoechst 33258 staining techniques. Simultaneously, they were scored for the presence of 24 mouse enzymes. The results confirm the assignments of 11 genes previously mapped by sexual genetics: Dip-1 and Id-1 to chromosome 1; Pgm-2 and Pgd to 4; Pgm-1 to 5; Gpi-1 to 7; Gr-1 to 8; Mpi-1 and Mod-1 to 9; Np-1 and Es-10 to 14. They also confirm chromosomally the assignments of 3 genes that were made by other somatic cell genetic studies: Aprt to 8; Hprt and a-gal to the X chromosome. But most importantly, four enzyme loci are assigned to four chromosomes that until now were not known to carry a biochemical marker which is expressed in cultured cells: Trip-1 to 10; Dip-2 to 18; Acp-1 to 12; and Ak-1 to 2. Cytogenetic examination of clones showing discordant segregation of HPRT and A-GAL, suggested the assignment of a-gal to region XE→XF of the mouse X chromosome. The cytologic studies provide a comparison between data from sexual genetics and somatic cell hybrids and validate hybrid cell techniques. They provide evidence of the reliability of scoring chromosomes by GTG and Hoechst staining and stress the importance of identifying clones with multiple chromosome rearrangements. Striking examples of nonrandom segregation of mouse chromosomes were observed in these hybrids with preferential retention of 15 and segregation of 11 and the Y chromosom

ISSN:1424-8581    

DOI:10.1159/000130799

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

In the hybrid mouse strain BDF1; some 35–40 % of spermatocytes had unpaired X and Y chromosomes in stages ranging from diplotene to first meiotic metaphase. This phenomenon varied significantly from mouse to mouse. In pooled material from Swiss Albino and CF1 mice, the corresponding frequency was 5.7 %. In C57 BL/6 mice, one of the parent strains of BDFj mice, the X and Y were separate in 7.7 % of the spermatocytes. Based on the behavior of the X and Y in the BDF1 strain, it is concluded that they do not pair, rather than initially pairing and then precociously separating. The factor interfering with the pairing of the X and Y does not affect the autosomes; possibly it is an incompatibility of the two sex chromosomes, which come from different inbred line

ISSN:1424-8581    

DOI:10.1159/000130800

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

We have studied possible sources of resting human lymphocyte DNA content variation among euploid males and females as determined by flow-microfluorometry. A major source of variation arises from instrumental instability, most notably flow-rate changes. This variation can be detected and minimized by the use of chicken erythrocytes as an internal standard. A second source of variation arises from differences in rates of lymphocyte stain uptake. The lowest coefficients of variation (0.3 %) among individuals of like sex, and optimal distinction between sexes, were achieved after exposing lymphocyte samples for 24 h to the hypotonic staining solution. Four males and females with either low or high relative DNA contents within their respective sexes showed correspondingly divergent values upon repeat venipuncture. Some of the observed interindividual DNA content variation might therefore reflect truly genetic differences. For two male samples with repeatedly divergent DNA content values, preliminary C-banding of conventional metaphases suggests corresponding differences in constitutive heterochromatin.

ISSN:1424-8581    

DOI:10.1159/000130801

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

G-band patterns of the Siberian snow sheep, Ovis nivicola alleni, 2n = 52, were compared with the patterns reported in 2n = 54 wild Asiatic mouflon and 2n = 54 North American sheep and those in domestic sheep with 2n = 54, 53, and 52. The three largest pairs of biarmed autosomes displayed indistinguishable, presumably homologous, G-banding patterns in all types of sheep. The banding and morphology of the fourth pair of biarmed autosomes in O. nivicola differed from those of the three translocation variants described in domestic sheep. Wild sheep with 2n = 54 may have evolved monophyletically from an ancestral 2n = 58–56–54 population or polyphyletically by a series of independent, nonrandom fusions. In contrast, the fourth pair of biarmed autosomes in o. nivicola and in 2n = 52 domestic sheep variants may have resulted from random fusions of different chromoso

ISSN:1424-8581    

DOI:10.1159/000130802

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

Common chromosome break points were found in a banding study of 25 chromosomally abnormal fibroblast clones derived from normal individuals and patients exposed to environmental carcinogens. Of 81 break points, 38 % appeared to be in terminal bands. This specificity did not appear to be the consequence of the biased recognition of exchanges. In addition, specificities for break points at exact interstitial loci were detected. The presence of clones in cultures grown in a wide variety of conditions, the finding of two identical clones in two independent lines from the same biopsy, and the absence of any obvious continuing instability in lines support the view that chromosomally abnormal fibroblasts occur in vivo.

ISSN:1424-8581    

DOI:10.1159/000130803

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

The proportion of cells with clonally derived chromosome rearrangements has been recorded at different passage levels in 16 lines of human fibroblast cultures derived from adults. All abnormal clone populations recognized at the lowest passage levels showed a stable or declining frequency relative to the normal cells, although 2 out of the 21 clones detected did show a transient increase. Only 2 clones were found at higher passage levels that were not previously identified at low passage. The observed selection against cells with rearrangements may reflect a general property of chromosome organization which ensures that cytogenetic abnormalities do not normally accumulate in rapidly dividing tissues.

ISSN:1424-8581    

DOI:10.1159/000130804

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

Computerized chromosome analyses have resulted in up to 25 % erroneous classifications, whereas a cytogenetically trained laboratory technician has an error rate of less than 0.1 % in the preparation of a karyotype. In the project reported here, computerized classification is eliminated, and, instead, the other steps of the analysis leading to the final karyotype are automated. In the instrument is a projection microscope, modified to project the image on paper before the operator. The slide is scanned on a motor-driven scanning table, in search of a suitable metaphase. The operator stops the scanning motor when a suitable metaphase comes into view. The individual chromosomes of the metaphase are then framed, using a view finder, and are identified, after which the chromosome number is entered on a keyboard. The instrument automatically ensures that, for each data entry, the framed chromosome is photographed in such a manner that the chromosome is placed in the proper location with the correct orientation in the karyotype. When all chromosomes have been identified, and the data have been keyed in, a photograph of the finished karyotype is presented. Marking the metaphase chromosomes on the paper, chromosomes are counted within 20 s. With conventional methods, a total chromosome analysis takes 3–6 h, but the above-described device requires 20–30

ISSN:1424-8581    

DOI:10.1159/000130805

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

A new meiotic phenomenon is described in male mice heterozygous for the male-sterile translocations T(10;13)199H, T(16;17)43H, and T(7;19)145H. The phenomenon consists of a nonrandom contact between the C bands of the X chromosome and the translocation configuration in diakinesis/metaphase I plates. Translocation configurations with positively heteropycnotic regions, often associated with the allocyclic X chromosome, are found in some early diakineses that have not been overtreated with alkali. Such heteropycnosis of a part of translocated autosome, apparently in phase with the allocyclic X, is typical for all three male-sterile translocations. In contrast to these findings, neither nonrandom contacts nor positive heteropycnosis of the translocation configuration can be found in males heterozygous for the translocation T(9;17)138Ca, which does not impair spermatogenesis. Dissociation of the X and Y at diakinesis is significantly enhanced in sterile males, though the occurrence of dissociation is evidently not related to the presence of the C-band contact between translocated chromosomes and the X. A working hypothesis is proposed, relating the observed nonrandom C-band contact and heteropycnosis of translocated chromosomes to a presumed impairment of X inactivation in primary spermatocytes and to consequent failure of spermatogenesis. An alternative explanation cannot be excluded, however, which would account for the hitherto available data without postulating any causal relationship between the meiotic findings and male sterility. Both alternatives are amenable to experimental verification.

ISSN:1424-8581    

DOI:10.1159/000130806

出版商:S. Karger AG    

年代:1977

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000130807

出版商:S. Karger AG    

年代:1977

数据来源: Karger