ISSN:1424-8581    

DOI:10.1159/000131827

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Meiotic nuclei preparations obtained from human fetal ovaries were studied with the silver-NOR technique. At leptotene, the NOR’s were located at the periphery of the nucleoli. The mean number of NOR’s per nucleus was 6.4. Moreover, 2–12 micronucleoli, each containing an Ag-positive zone, were observed. At pachytene, each nucleolus was divided into two zones, one of which was Ag-positive. The mean number of Ag-positive zones was 2.1 per nucleus. The subterminal region of the short arm of nucleolar bivalents was in contact with the argyrophilic nucleolar zone. In most cells, micronucleoli were dispersed between the bivalents. A single rounded body which stained heavily with silver was consistently observed. At early diplotene, the NOR’s separated, appearing again as distinct rounded Ag-positive structures embedded in the peripheral part of the nucleoli. The silver-stained round body was still visible. Eight to twelve micronucleoli were observed. At a more advanced stage of diplotene, the number of micronucleoli increased, varying from 20 to 50 per nucleus. These observations suggest that the micronucleoli, already visible at the leptotene stage, are the morphological expression of an early transcription of amplified rDNA. The biological significance of the Ag-positive round body remains obscure, but the consistency of its appearance suggests that it has a specific function somehow related to nucleolar p

ISSN:1424-8581    

DOI:10.1159/000131828

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

We previously reported that the structural gene for epidermal growth factor receptor (EGFR) can be mapped to the p22→qter region of human chromosome 7 (Shimizu et al., 1979, 1980). In the present study, we produced two series of human-mouse cell hybrids by fusing mouse A9 cells that are deficient in EGFR with the human diploid fibroblast lines GM1356, 46, XX, t(l;7)(p34;pl3), and GM2068, 46, XX, t(6;7)(q27;q22), both of which possess EGF receptors. Expression of EGF binding ability in the former series of cell hybrids was correlated with the retention of the human translocation chromosome containing the 7p13→qter region, and in the latter series of cell hybrid it was correlated with the retention of the human translocation chromosome containing the 7pter→q22 region. Therefore, the EGFR gene can be localized in the p13→q22 region of chrom

ISSN:1424-8581    

DOI:10.1159/000131829

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Concordant segregation analysis of Chinese hamster (Cricetulus griseus) isozymes and chromosomes segregating from interspecific somatic cell hybrids made with mouse C11D cells revealed the locations of GPI and PEPD on chromosome 9 and TPI on chromosome 8 in both euploid Chinese hamster and CHO cells. The patterns of electrophoretically detectable shift mutants of these loci in CHO cells were consistent with the observed presence of two normally banded chromosome 8’s and monosomy for chromosome 9. These findings and the isolation of three independent, null PEPD mutants in only 527 ethyl methansulfonate-exposed clones indicate that the high frequency of recovery of recessive drug resistant mutants in CHO cells may be due not only to haploidy caused by deletions and monosomy but also by great sensitivity of certain loci to particular mutagen

ISSN:1424-8581    

DOI:10.1159/000131830

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Trypsinization, used as a pretreatment for Giemsa banding human chromosomes, produced a progressive degradation of metaphase chromosome structure. Over the visible range of G-banding in the light microscope various levels of chromosome structure were revealed in the scanning electron microscope.

ISSN:1424-8581    

DOI:10.1159/000131831

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

H-W (H-Y) antigen was investigated in diploid, triploid, and tetraploid Xenopus hybrids. These hybrids differ from each other with respect to their sex chromosome constitution–they all have a single W chromosome but one to three Z chromosomes. The H-W antigen concentration is reduced with increasing numbers of Z chromosomes. In the diploid and triploid hybrids the single W chromosome is able to guarantee ovary development, but among the tetraploids both male and female animals occur. However, both sexes have identical H-W antigen titers in the somatic tissues. It can be concluded that in these tetraploid hybrids with a ZZZW sex chromosome complement, the amount of H-W antigen is too low to sustain ovary development in all case

ISSN:1424-8581    

DOI:10.1159/000131832

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The effects of maternal aging on the configuration of chiasmata, formation of univalents, and segregation of first meiotic (MI) chromosomes were investigated in young (5–8 mo) and old (16 19 mo) Chinese hamsters. Primary oocytes were collected only from mature follicles approximately 10 h before ovulation, and secondary oocytes were obtained from the oviducts 5 h after spontaneous ovulation. The average number of chiasmata per oocyte was significantly smaller in aged hamsters than in the young hamsters (P < 0.001). Terminal chiasmata were found more frequently in the former group than in the latter one (P < 0.001). These results coincided well with findings in the mouse. Since the 11 meiotic chromosomes could be divided into four morphologically distinguishable subgroups, it was possible to determine whether the same bivalent forming univalents at MI actually underwent nondisjunction in the following meiotic division. The incidence of both MI oocytes with a univalent pair and aneuploid MII oocytes due to first meiotic nondisjunction was significantly higher in the aged group than in the young group (P < 0.01 and P < 0.05, respectively). However, univalents occurred almost exclusively in the smallest metacentric chromosome group (96%), whereas nondisjunction took place nearly equally in each chromosomal subgroup. These results clearly showed that there was no correlation between the univalents seen at MI and nondisjunction during the first meiotic divisio

ISSN:1424-8581    

DOI:10.1159/000131833

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The frequency and type of chromosome abnormalities were analyzed in 917 female pronuclei in Syrian hamster eggs fertilized by human sperm. Analysis at this stage allows detection of errors which have occurred during meiosis I and II. The chromosomes were Q-banded to identify individual chromosomes and detect subtle alterations. Thirty-three (3.6%) of the hamster egg complements were abnormal: 19 (2.1%) were hypohaploid, seven (0.76%) were hyperhaploid, two (0.2%) had double aneuploidy, and five (0.5%) had a structural chromosome abnormality. Since there were significantly more hypohaploid than hyperhaploid complements, a conservative estimate of aneuploidy can be derived by doubling the frequency of hyperhaploid complements. Thus a minimal estimate of aneuploidy (single, 1.5%, and double, 0.2%) is 1.7% and a minimal estimate of the total frequency of abnormalities is 2.2%. All chromosome groups were represented among the aneuploid complements suggesting that all chromosomes are susceptible to non-disjunction.

ISSN:1424-8581    

DOI:10.1159/000131834

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The chromosome localization and gene synteny of soluble malate dehydrogenase (MDH1), soluble isocitrate dehydrogenase (IDH1), mitochondrial superoxide dismutase (SOD2), phosphoglucomutase-3 (PGM3), mitochondrial malate dehydrogenase (MDH2), (3-glucuronidase (GUSB ), nucleoside phosphorylase (NP), pyruvate kinase M2 (PKM2), hexosaminidase A (HEXA), inosine triphosphatase (ITPA), and N-acetyl-α-D-galactosaminidase (NAGA) were determined in the rhesus monkey using somatic cell hybrids. Comparison with the human and Pongidae syntenic groups shows that chromosome banding homologies do not always correlate with gene mapping data

ISSN:1424-8581    

DOI:10.1159/000131835

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Differences in the size and distribution of chromosomal C-bands were investigated in 17 strains of Mus musculus. Each strain was found to have a characteristic C-band pattern. Closely related strains, substrains, and congenic strains, e.g., DDD and DRC, BALB/c and BALB/cAn, and CBA/J and CBA/H-T6, showed a similar C-band pattern, whereas striking dissimilarities in the C-band pattern was observed between the related strains, DDD and DHS, and SJL and SWJ, which were established independently from noninbred stocks of dd and Swiss mice, respectively. Virtually every autosome except for 1 and 2 showed C-band variation among the strains. The size of the C-band on 1,2, and the X appeared to be fairly constant among the strains. All chromosome pairs were homomorphic in each inbred animal; the between-strain difference in the C-band size was most easily observed in F1hybrids which showed the heteromorphic C-band patterns, expected from the parents. Measurements of the chromosome lengths of the heteromorphic pairs in a (C57BL/6J x DDD) F1 hybrid disclosed that homologues which had different size C-band had significantly different lengths, and homologues, one of which lacked C-band material, were the same length. Heteromorphism in the length of Y chromosome was also found; BALB/cAn had a Y smaller than the 19. These chromosome markers appear to be useful for characterizing each strain as well as for monitoring inbred stocks.

ISSN:1424-8581    

DOI:10.1159/000131836

出版商:S. Karger AG    

年代:1983

数据来源: Karger