ISSN:1424-8581    

DOI:10.1159/000131295

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

We have used trypsin-Wright’s banding (“GTG-banding”) to analyze the chromosome content in two sublines of the SV40-transformed human cell line LNSV, derived from fibroblasts of a patient with HPRT deficiency. Both LNSV sublines (GM-847 and “LNSV”) were heteroploid and showed considerable numerical and structural chromosome variability. Nineteen rearranged chromosomes which were observed at high frequency have been set aside as “marker chromosomes,” and their probable derivation from normal human chromosomes has been described in Paris Conference (1971) nomenclature. Heterogeneity within these uncloned sublines appears to increase with time in culture, and no evidence was found for evolution of a karyotypically stable cell population. The results are of general significance for cell genetic studies using establish

ISSN:1424-8581    

DOI:10.1159/000131296

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Treatment of the chromosomes of 25 rodent species with a 50° C hypotonic solution and Giemsa staining permitted identification of the heterochromatic X chromosome in 24 species. With this technique, the facultative heterochromatic X chromosome or the facultative portion of large, composite-type X chromosomes is stained darker than the other chromosomes, allowing it to be distinguished from the homologous euchromatic X chromosome in female metaphase cells. Intense staining of the single X chromosome was not observed in male metaphase cells. It is suggested that this differential staining of one of the two X chromosomes might be due to qualitative differences in chromosomal proteins rather than to differences in the degree of chromosomal condensation or in DNA base sequence

ISSN:1424-8581    

DOI:10.1159/000131297

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

In human male meiotic prophase, nonhomologous pairings and connections between C-heterochromatic regions were demonstrated by C-banding and G-ll staining. Approximately 40% of the pachytene stages exhibited bivalent associations at regions of C-heterochromatin. Nonhomologous associations were seen between all possible morphological types of bivalents. Evidence is submitted suggesting that nonhomologous associations between regions of C-heterochromatin are a fairly common event in many organisms, including man, and the possible roles of this phenomenon in meiosis are discussed.

ISSN:1424-8581    

DOI:10.1159/000131298

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Leukocyte and kidney cell cultures were used to examine the sex chromosomes of Japanese freshwater eels (Anguilla japonica) and conger eels (Astroconger myriaster). The conspicuous presence of ZW sex chromosomes, due to a drastic reduction in size of the W, was confirmed in both species, where the Z was the largest metacentric and the W was the smallest metacentric in a diploid karyotype of 38 chromosomes in both species. These species are the first examples of the ZW type of heteromorphism in eels.

ISSN:1424-8581    

DOI:10.1159/000131299

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Cells of the mouse L strain and the Chinese hamster CHO line were treated with 33258 Hoechst, rubidazone, and a combination of these. Recovering cell populations following the drug removal exhibited a high frequency (20–50%) of metaphases with diplochromosomes (endoreduplication), especially in the combination treatment series (up to more than 70% in the L strain). Such a procedure should be useful in probing the mechanisms of the endoreduplication proces

ISSN:1424-8581    

DOI:10.1159/000131300

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Chromosomal breakage in peripheral lymphocytes, cultured fibroblasts, and long-term lymphoblastoid cell lines was investigated in five hitherto undescribed patients with ataxia telangiectasia (AT). Increased chromosomal instability was observed in lymphocytes and fibroblasts, and clones possessing a Dq+ marker were observed. Breakage rates were significantly higher in the fibroblasts than in the lymphocytes of AT patients or in similar tissues from patients with Bloom syndrome or Fanconi anemia. However, chromosome breakage in lymphoblastoid lines established from these five AT patients and six others did not differ from controls. These observations suggests that selection pressures, in vivo or in vitro, or both, act differently on the expression of chromosomal instability in these various cell types.

ISSN:1424-8581    

DOI:10.1159/000131301

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Diplotene chiasma frequencies from “early” (day 16) fetal oocytes are significantly greater than the average from “late” (day 18) oocytes. A decrease in chiasma frequencies from both ages was found at diakinesis/MI in oocytes of young or old adult females, indicating a loss of chiasmata and/or terminalization. A greater number of type I univalents was found in “late” oocytes than “early” oocytes entering diplotene. No differences were found in chiasma frequencies of male diplotene spermatocytes studied at 23 days, 2 months, or 24 months of age. A greater chiasma frequency was generally found in the female than the male at a

ISSN:1424-8581    

DOI:10.1159/000131302

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

A medium is described which can be used for the selection of somatic cell hybrids between HPRT– and APRT– mutant cells. This medium, called GAMA, contains as its relevant constituents the following: the purines guanine and adenine and the purine biosynthetic pathway inhibitors mycophenolic adic, which blocks conversion of adenine ribonucleotides to guanine ribonucleotides, and azaserine, which blocks de novo purine synthe

ISSN:1424-8581    

DOI:10.1159/000131303

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Chromosomes were studied in ovulated oocytes from Syrian hamsters (Mesocricetus auratus) and Chinese hamsters (Cricetulus griseus) to assess the degree of chromosomal imbalance after first meiotic division of oogenesis. Only one hyperploid oocyte among 307 studied was detected in the former, and none in oocytes from the latter species. Structural chromosome alterations, single chromatids due to presegregation, and diploid chromosome sets resulting from meiotic blockage were not observed. The hormones which were used to stimulate ovulation apparently did not enhance first meiotic cleavage errors in these hamster oocytes. The low figures of chromosomal anomalies in hamster oocytes are compared to those from a large sample of mouse oocytes obtained from three different strains and prepared under identical conditions. The relevance of these findings to the obviously higher impact of chromosomal aneuploidy in man is discussed.

ISSN:1424-8581    

DOI:10.1159/000131304

出版商:S. Karger AG    

年代:1979

数据来源: Karger