摘要:

One of the inherent difficulties associated with the accurate detection of sister chromatid exchanges (SCE’s) in vivo is the maintenance of a continuous supply of 5-bromo-2’-deoxyuridine (BrdU) for differential staining of sister chromatids. We have developed a simple, reproducible intraperitoneal technique which has the advantages of continuous BrdU infusion and is less stressful than presently available methods. Additionally, a gentle trypsinization methodology was developed to obtain relatively large numbers of metaphases from fetal tissues. Using these techniques, we examined the induction of SCE by 7,12-dimethylbenz(a)anthracene (DMBA) when injected into pregnant CD rats on days 11, 13, 15, and 16 of gestation. The levels of SCE induced were slightly higher in fetal than maternal tissue, although not significan

ISSN:1424-8581    

DOI:10.1159/000131846

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Synaptonemal complexes (SC’s) were compared to their chromosomes by transmission electron microscopy (TEM) of whole-mount spreads from 42 male chickens. Individual macrochromosomal SC’s were first identified in heterokaryotypes and later by their centromere index. For all nine macrochromosomes (eight autosomes and the Z sex chromosome), the relative length (rl) of each SC corresponded to that of its mitotic and meiotic chromosome, and the centromere position along each SC corresponded to that of its mitotic chromosome. An idiogram was constructed which included the 30 microchromosomes. The idiogram revealed a graded series of SC lengths with a 30-fold difference between the longest and the shortest SC. Microchromosomal SC’s comprised 35% of the genome l

ISSN:1424-8581    

DOI:10.1159/000131847

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The process of human chromosome segregation in human myeloma x mouse myeloma cell hybrids was investigated. The human myeloma cells were derived from two different patients. Fifty-eight independent hybrid lines were obtained. A representative number of cells from each line were karyotyped and isozyme markers for a number of the chromosomes retained were analyzed. Statistical analyses were performed on 113 cells from five different cell lines showing the largest complement of human chromosomes. A log-linear models approach to the statistical analysis was used to predict the expected chromosome segregation under a variety of assumptions concerning the dependency relationship between the pattern of loss and the specific chromosomes both within and between cell lines. Human chromosome segregation occurring after the hybrids were grown continuously in suspension for several months was also studied. Results indicated a statistically significant dependency among patterns of loss of specific chromosomes, with certain chromosomes preferentially retained and others lost more often than expected under the assumption of randomness of segregation.

ISSN:1424-8581    

DOI:10.1159/000131848

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

When activated by near-ultraviolet light, 8-methoxypsoralen can react with pyrimidine bases to produce mono-adducts in DNA. Upon further irradiation these mono-adducts can be converted to interstrand crosslinks, but if the re-irradiation is carried out in the absence of unbound 8-methoxypsoralen, no new mono-adducts can be formed. The effects of re-irradiation are, therefore, a consequence of the conversion of mono-adducts into crosslinks. Here we report the types of chromosomal aberrations produced by re-irradiation and, hence, by DNA crosslinks. Our results demonstrate that crosslinks induce a wide variety of chromosomal aberrations in the first division after treatment. In addition, crosslinks are shown to induce new aberrations in second-division cells, a result which shows that the crosslink or some lesion derived from it survives at least one round of DNA replication.

ISSN:1424-8581    

DOI:10.1159/000131849

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

A temperature sensitive mutant exhibiting a very high level of chromosomal aberrations has been isolated from the Chinese hamster cell line E36. The chromosome aberrations, which include chromosome and chromatid breaks, multiradial configurations, dicentrics, and pulverizations, start to appear 1 h after a shift in temperature from 34°C to 40.5°C. The rate of sister chromatid exchange is not increased in this mutant. Analysis of somatic cell hybrids indicates that the mutation in this temperature sensitive mutant is dominan

ISSN:1424-8581    

DOI:10.1159/000131850

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Human tissues contain two isozymes of neutral a-glucosidase, neutral a-glucosidase AB and neutral a-glucosidase C (a-D-glucoside glucohydrolase, EC 3.2.1.20). The two isozymes, initially defined on the basis of differences in electrophoretic mobility in starch gel, have also been shown to have other distinguishing biochemical characteristics including different substrate specificites. Rodent tissues contain apparently homologous isozymes of neutral a-glucosidase. The mouse and human a-glucosidase C isozymes, but not the AB isozyme(s), can be distinguished by the difference in their electrophoretic mobility. This difference has previously enabled us to use human-mouse somatic cell hybrids to assign the structural gene for human a-glucosidase C to chromosome 15. We now report the differentiation of mouse and human neutral a-glucosidase AB isozymes by rocket immunoelectrophoresis, using an antibody raised in mice against purified human placental neutral a-glucosidase AB. This antibody precipitated both the A and B bands of human neutral a-glucosidase AB and did not cross react with mouse enzyme as determined by Ouchterlony double immunodiffusion and by rocket immunoelectrophoresis. Using this antibody, the segregation of human neutral a-glucosidase AB was examined in 41 mouse x human hybrid clones. Thirty-eight hybrid clones, derived from fusions of RAG x seven different human cells, showed 100% concordant segregation of human neutral a-glucosidase AB and the 11. Three additional clones, derived from a fusion of tetraploid murine erythroleukemia cells (2S-MEL) x diploid human fibroblasts carrying a translocation chromosome(s) allowed the regional localization of the gene to the long arm of 11 (11q13→11qter

ISSN:1424-8581    

DOI:10.1159/000131851

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Biochemical analysis of cytogenetically defined rodent-owl monkey hybrid cell lines segregating owl monkey chromosomes allowed the assignment of 14 structural gene markers to seven owl monkey karyotype V (K-V, 2n = 46) chromosomes. Comparative study of assigned gene loci to chromosomes of owl monkey karyotype V (K-V, 2n = 46) and karyotype VI (K-VI, 2n = 49/50) provides the first evidence supporting some of the previously proposed mechanics of chromosomal rearrangements responsible for the great karyotypic diversity in owl monkeys. In addition, chromosome homologies deduced from gene loci of Aotus and other primates are compared here to determine the conservation or modification of chromosome morphology in the course of primate evolution. The data demonstrate the usefulness of gene mapping as an alternative to banding patterns for obtaining evidence on chromosome evolution.

ISSN:1424-8581    

DOI:10.1159/000131852

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

A (G + C)-rich satellite DNA component (p= 1.716 g/ml) has been fractionated from the total DNA of the Iranian subspecies of the Asiatic wild ass, Equus hemionus onager, by successive dactinomycin-CsCl and netropsin sulfate-CsCl isopycnic gradients. Complementary 3H-RNA (cRNA) transcribed from the satellite DNA hybridized predominantly to the centromeric and telomeric constitutive heterochromatic regions of onager chromosomes. These studies have suggested that satellite DNA’s with similar sequences are present in the centromeric, as well as telomeric, heterochromatic regions of some onager chromosomes. The centromeric region of the fusion metacentric t(23;24) of the onager is deficient in sequences homologous to the onager 1.716 g/ml satellite DNA, indicating a loss of satellite DNA during fusion or an amplification of the satellite DNA in the centromeric regions of the acrocentric chromosomes 23 and 24 subsequent to fission. Sequences complementary to onager 1.716 g/ml satellite DNA show extensive hybridization to the constitutive heterochromatin of the feral donkey (E. asinus) karyotype, consistent with a view of conservation and amplification of similar or identical sequences in the two specie

ISSN:1424-8581    

DOI:10.1159/000131853

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Based on G- and C-banded karyotypes of 10 specimens of rice rats, genus Oryzomys (a member of the macconnelli-capito complex but species identification is not possible at this time) from a single isolated population, we found at least nine different centric fusion/fission polymorphisms. No two individuals examined had the same karyotype. Polymorphic variation appears to be stable in the population and not the result of hybridization, human disturbance, or non-specific mutagenic agents. Among the 14 largest chromosomes, polymorphism is restricted to fusion/fission rearrangements. Among the smaller ones, there is polymorphism in the total number of euchromatic arms, which indicates that rearrangements other than fusion/fission exist within our sample. Data from these rice rats document the presence of a greater number of chromosomal polymorphisms within a single, natural population than have previously been reported in a higher vertebrate.

ISSN:1424-8581    

DOI:10.1159/000131854

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The phylogenetic relationships of three plecotine bat genera were studied by comparison of chromosome banding patterns. The G-banded karyotypes of Euderma maculatum and Idionycteris phyllotis were found to be very similar, differing by only two pericentric inversions. Plecotus townsendii possessed a strikingly different G-band karyotype, which differed from that of Euderma and Idionycteris by several fusions and an inversion in the X chromosome. Only five pairs of biarmed chromosomes and two pairs of small acrocentric chromosomes were shared as direct homologs between Plecotus and the other two genera. These results indicate a more complex derivation for the Plecotus karyotype than indicated by Williams et al. (1970) or Bickham (1979). The degree of non-matching of biarmed chromosomes indicates that the ancestor that gave rise to the Plecotus line and the Eudermaj Idionycteris line possessed a karyotype with at least 15 pairs of telocentric or acrocentric chromosomes and a diploid number of at least 42. This ancestral line may have been characterized by a Myotis-like karyotype. The plecotine genera are related to Myotis as evidenced by the possession of all four biarmed chromosomes found in that genus. The occurrence of the same small biarmed chromosome in Idionycteris, Euderma (11), Plecotus (10), and Myotis (16/17 of Bickham) clearly unites the plecotine genera with the Myotis group in contrast to the opinion of Williams et al. (1970). This chromosome is believed to be the result of an inversion in an acrocentric chromosome of the original vespertilionid karyotype of 50 or more telocentric or acrocentric chromosomes as seen in the genus Eptesicus. The data derived from these comparisons are presented cladistically to make the information more accessible to systematic zoologists.

ISSN:1424-8581    

DOI:10.1159/000131855

出版商:S. Karger AG    

年代:1983

数据来源: Karger