ISSN:1424-8581    

DOI:10.1159/000132036

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

Retinoblastoma (Rb) is an uncommon childhood tumor of the neural retina with a significant genetic component in its etiology. A small proportion of patients have a deletion in chromosome 13 encompassing band 13q14, an observation which permitted the assignment of the RBI locus to this region. About 20% of Rb tumors exhibit microscopic deletions of band 13q14 or monosomy 13. Trisomy 1q and i(6p) have also been reported in a high percentage of tumors. We analyzed the chromosome complements from direct preparations of 10 Rb tumors derived from seven patients. Modal chromosome numbers ranged from 45 to 48, and occasional duplications of the genomes were noted. In general, the tumors were chromosomally stable, although karyotypic evolution and random chromosome loss were encountered. Consistent abnormalities included trisomy 1q, i(6p), 6q-, and del(13)(q12→14). One patient with bilateral Rb had three tumor clones (two in one eye and one in the other) with chromosome abnormalities unrelated in origin. A second patient with unilateral Rb had two tumor clones with chromosome abnormalities again unrelated in origin. These two patients provide some of the first cytogenetic evidence for the multifocal origin of primary Rb. In the untreated tumor of a third patient, a homogeneously staining region (HSR) was detected in 1p32, indicating gene amplication in vivo; previously, an HSR at this site has been reported in the established Rb cell line Y7

ISSN:1424-8581    

DOI:10.1159/000132037

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

PHA-stimulated growth of human lymphocytes in the presence of idoxuridine (IUdR) results in chromosomal decondensation and fragility of large heterochromatic regions. This instability is especially evident in the heterochromatic region of chromosome 9 (9h). A high frequency of micronuclei is seen in all IUdR-treated cultures. By a combination of chromosomal localization of induced aberrations, analysis of metaphases with prematurely condensed micronuclear chromatin, and specific staining of 9h in interphase micronuclei, it can be shown that 80–90% of all micronuclei contains 9h material. This pattern is found whether the heterochromatic region is situated on the long arm or the short arm of chromosome 9. These observations suggest that IUdR-induced micronucleation may be a valuable method for separation of the long and short arms of human chromosome

ISSN:1424-8581    

DOI:10.1159/000132038

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

A search for genes located on human chromosome 21 resulted in the isolation of a HeLa cDNA clone, pUNC724, which hybridized to 3.7 and 2.5 kilobase (kb) EcoRl fragments on each of the human acrocentric chromosomes. In situ hybridization further localized pUNC724 to the pericentromeric region of the human acrocentrics. Two other EcoRI fragments that hybridized to pUNC724 were assigned to the long arms of chromosomes 1 and 18. The pUNC724 sequence does not appear to be related to ribosomal or satellite DNA sequences. The juxtaposition of DNA sequences homologous to pUNC724 and ribosomal DNA sequences presumably occurred within the past thirty-five million years, following the divergence of the lines leading to man and the New World owl monkey, Aotus trivirgatus—pUNC724 is not syntenic with the single chromosome containing ribosomal DNA sequences in the owl monke

ISSN:1424-8581    

DOI:10.1159/000132039

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

Silver-stained pachytene cells of male deer mice, Peromyscus maniculatus, which were heterozygous for a naturally occurring pericentric inversion of chromosome 6, were analyzed by light microscopy. The presence of the terminally positioned inversion, involving approximately 30% of the length of chromosome 6, was detected by G-banding. Within the inversion, C-band-positive heterochromatin was restricted to the centromeric region. Silver-staining of spermatocytes revealed the synaptonemal complexes (SCs) of the autosomal bivalents and the X-Y chromosome association. Pachytene cells were scored for the presence of inversion loops corresponding to the pericentric inversion of chromosome 6. Possible loop 6 configurations were detected in less than 1% of the cells examined, the vast majority of cells having regularly formed autosomal SCs similar to those reported for homomorphic chromosome pairs in other rodent species. It appears, therefore, that in these mice the inverted region of chromosome 6 was heterosynaptic throughout pachytene. Heterosynapsis is hypothesized as a mechanism which might obviate the production of duplication and deletion chromatids expected from crossing-over in pericentric inversion loops. The observation of heterosynaptic pairing in the inverted segment and the hypothesis of inversion heterosynapsis as a mechanism averting gametic loss are consistent with the widespread occurrence of pericentric inversion polymorphisms in P maniculatus and the apparent failure of pericentric inversions to genetically isolate populations of this species.

ISSN:1424-8581    

DOI:10.1159/000132040

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

A Cellogel procedure for electrophoretic characterization of formaldehyde dehydrogenase (FDH) is described. Isozyme profiles in 24 different human tissues indicate extreme quantitative heterogeneity and the existence of one major form and at least two minor forms of FDH in man. Biochemical and genetic analysis of the enzyme in Chinese hamster-human somatic cell hybrids has shown that the functional molecule of FDH is probably composed of two identical subunits and that its structural locus may be assigned to human chromosome 4.

ISSN:1424-8581    

DOI:10.1159/000132041

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

Chromosome replication in mammalian cells is an ordered phenomenon. This is true also for the condensation in G2 of the heterochromatic chromosomal regions in mouse cells. The generality of this phenomenon and its mechanism are not known, nor is it known whether the order of condensation of the heterochromatic chromosomal segments in G2 reflects the order of replication or is independent of it. We determined the order of replication during the S phase and of condensation in G2 of the short heterochromatic chromosomal regions in the rat kangaroo cell line PtK2. The kinetics of condensation of these regions in G2 was studied in cells treated with Hoechst 33258. Their order of replication was established with the use of a sensitive technique based on the treatment of living cells with 5-bromodeoxyuridine and Hoechst 33258. Our results show that these regions exhibit a similar pattern of replication in S and condensation in G2.

ISSN:1424-8581    

DOI:10.1159/000132042

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

In women X;Y translocations usually arise as Xp-Yq exchanges. We describe a 17-year-old female with streak gonads, some minor features of Turner’s syndrome, and an X;Y translocation involving an exchange between Xq and Yq. Histological examination of the gonads revealed a fibrous stroma with prominent hilar cells. Cultured fibroblasts and peripheral lymphocytes were typed H-Y∼. Examination of a buccal smear revealed a single intranuclear structure with the appearance of both a Barr body and a fluorescent Y body. This finding was consistent with the results of BrdU studies showing that the translocation X chromosome had been inactivated in all cells analy

ISSN:1424-8581    

DOI:10.1159/000132043

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

In situ chromosomal hybridization of a probe for part of the lamda light chain constant region (Cλ) has demonstrated that the 22q11 breakpoints of chronic myelogenous leukemia (CML) t(9;22) and Burkitt lymphoma t(8;22) are not identical. For CML, the breakpoint is distal to the IGLC genes, whereas for Burkitt lymphoma it is proximal. The study provides direct evidence for regional assignment of the IGLC gene cluster to 22q11

ISSN:1424-8581    

DOI:10.1159/000132044

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

The Chinese hamster genes ADK, NP, ESD, PGM2, PEPS, PEPB, GLO, and GSR, all of which are on Chinese hamster chromosome 1, were assigned to CHO-LA chromosomes by analysis of the segregation of CHO isozymes and chromosomes from interspecific somatic cell hybrids made with CHO cells and mouse C11D cells. One allele of each of these eight loci remained linked on the normal chromosome 1 homolog. For seven loci, the other allele remained linked on chromosome Zl, but ESD was shown to have been translocated to chromosome Z6 (Chinese hamster chromosome 5q+). Ag-NOR staining of CHO chromosomes indicated that the (1; 5) translocation was very likely reciprocal, since the Chinese hamster chromosome 5, which gave rise to the CHO Z6, lacks an NOR and the Zl now has one. These data allowed regional assignment of ESD to the distal portion of Chinese hamster chromosome 1p and provided genetic evidence for the origin of CHO chromosomes Z1and Z6 from Chinese hamster chromosomes 1 and 5. Induced electrophoretic shift mutations of ESD and positive Ag-NOR staining for the rRNA genes on the Z1 showed that the activities of the genes lying close to the translocation breakpoints were maintained.

ISSN:1424-8581    

DOI:10.1159/000132045

出版商:S. Karger AG    

年代:1984

数据来源: Karger