Dual-colour FISH analysis to characterize a marker chromosome in cytochrome P450 2B1 recombinant V79 Chinese hamster cells.
(17/1355)
Recombinant V79 Chinese hamster cell lines have been constructed for the expression of useful functions, e.g. cytochromes P450, in order to study metabolism-dependent toxicity. Recombinant cell lines are derived as single clones upon gene transfer and selection from the parental V79 cell line. It is of fundamental importance for a reliable application of the recombinant cell lines to show that the original biological characteristics of the parental line are maintained. As part of these efforts, fluorescence in situ hybridization with Chinese hamster chromosome-specific DNA libraries was performed in order to identify the origin of the chromosomes from which a marker chromosome present in the recombinant cell line V79MZr2B1 was derived, which could not be identified by standard cytogenetic techniques. (+info)
Chediak-Higashi syndrome associated with maternal uniparental isodisomy of chromosome 1.
(18/1355)
Chediak-Higashi syndrome (CHS) is a rare autosomal recessive disorder (incidence around 1 in 106 births), characterised by a complex immunologic defects, reduced pigmentation, and presence of giant granules in many different cell types. It most likely results from defective organellar trafficking or protein sorting. The causative gene (LYST) has recently been identified and shown to be homologous to the beige locus in the mouse. CHS has always been reported associated with premature-termination-codon mutations in both alleles of LYST. We report a unique patient with CHS, who was homozygous for a stop codon in the LYST gene on chromosome 1 and who had a normal 46,XY karyotype. The mother was found to be a carrier of the mutation, whereas the father had two normal LYST alleles. Non-paternity was excluded by the analysis of microsatellite markers from different chromosomes. The results of 13 informative microsatellite markers spanning the entire chromosome 1 revealed that the proband had a maternal isodisomy of chromosome 1 encompassing the LYST mutation. The proband's clinical presentation also confirms the absence of imprinted genes on chromosome 1. (+info)
Cytogenetic monoclonality in multifocal uroepithelial carcinomas: evidence of intraluminal tumour seeding.
(19/1355)
Twenty-one multifocal urinary tract transitional cell carcinomas, mostly bladder tumours, from a total of six patients were processed for cytogenetic analysis after short-term culturing of the tumour cells. Karyotypically related, often identical, cytogenetically complex clones were found in all informative tumours from each case, including the recurrent tumours. Rearrangement of chromosome 9, leading to loss of material from the short and/or the long arm, was seen in all cases, indicating that this is an early, pathogenetically important event in transitional cell carcinogenesis. The presence of related clones with great karyotypic similarity in anatomically distinct tumours from the same bladder indicates that multifocal uroepithelial tumours have a monoclonal origin and arise via intraluminal seeding of viable cancer cells shed from the original tumour. Later lesions may develop also from cells shed from the so called second primary tumours. The relatively complex karyotypes seen in all lesions from most cases argue that the seeding of tumour cells is a late event that succeeds the acquisition by them of multiple secondary genetic abnormalities. (+info)
Nuclear organization of mammalian genomes. Polar chromosome territories build up functionally distinct higher order compartments.
(20/1355)
We investigated the nuclear higher order compartmentalization of chromatin according to its replication timing (Ferreira et al. 1997) and the relations of this compartmentalization to chromosome structure and the spatial organization of transcription. Our aim was to provide a comprehensive and integrated view on the relations between chromosome structure and functional nuclear architecture. Using different mammalian cell types, we show that distinct higher order compartments whose DNA displays a specific replication timing are stably maintained during all interphase stages. The organizational principle is clonally inherited. We directly demonstrate the presence of polar chromosome territories that align to build up higher order compartments, as previously suggested (Ferreira et al. 1997). Polar chromosome territories display a specific orientation of early and late replicating subregions that correspond to R- or G/C-bands of mitotic chromosomes. Higher order compartments containing G/C-bands replicating during the second half of the S phase display no transcriptional activity detectable by BrUTP pulse labeling and show no evidence of transcriptional competence. Transcriptionally competent and active chromatin is confined to a coherent compartment within the nuclear interior that comprises early replicating R-band sequences. As a whole, the data provide an integrated view on chromosome structure, nuclear higher order compartmentalization, and their relation to the spatial organization of functional nuclear processes. (+info)
Significant differences in the frequency of transcriptional units, types and numbers of repetitive elements, GC content, and the number of CpG islands between a 1010-kb G-band genomic segment on chromosome 9q31.3 and a 1200-kb R-band genomic segment on chromosome 3p21.3.
(21/1355)
We determined the nucleotide sequence of the entire 1,010,525-bp insert contained in CEPH YAC clone 867e8. This human genomic segment was derived from chromosome 9q31.3 and corresponds to a G-band region. We compared this segment, in terms of structure, with a previously characterized 1,201,033-bp sequence in CEPH YAC936c1 that had come from a portion of human chromosome 3p21.3 corresponding to an R-band region. The two segments were significantly different with respect to the frequency of transcriptional units, the types and numbers of repetitive elements present, their GC content, and the number of CpG islands. Alu elements, GC content, and CpG islands all showed positive correlations with the abundance of exons, but the distribution of LINE1s did not. These observations might reflect an influence of the first three of these features on the functions or expression of genes in the respective regions. In addition to a novel gene (F36) lying at the centromeric end of the 9q segment, we found a cluster of placenta-specific genes within a small section (about 400 kb) on the telomeric side of YAC867e8. This cluster consisted of four apparently unrelated ESTs and two genes, pregnancy-associated plasma protein-A (PAPP-A) and a novel gene (tentatively named EST-YD1). Our characterization of the two chromosomal regions provided evidence that genes are not evenly distributed throughout the human genome, and that gene richness is correlated with the GC content and with the frequency of either Alu elements or CpG islands. (+info)
Chromosomal instability in acute myelocytic leukemia and myelodysplastic syndrome patients among atomic bomb survivors.
(22/1355)
To clarify the mechanism of leukemogenesis in atomic bomb survivors, leukemic cells were investigated using fluorescence in situ hybridization (FISH) analysis on the basis of conventional G-banding in patients with a history of radiation exposure and also in de novo patients. Conventional G-banding showed higher incidences (p < 0.005) of structural and numerical abnormalities without any specific types of chromosome aberrations in the group exposed to a dose of more than one Gy, compared to the non-exposed group. FISH analysis revealed significantly higher incidences (P < 0.05) of subclones with monosomy 7 and deletion of the 20q13.2 region, which were not found in conventional cytogenetic analysis in the exposed group (more than one Gy) compared to the non-exposed controls. Furthermore, segmental jumping translocation (SJT) of the c-MYC gene region was observed only in the exposed group. These chromosomal instability suggested that the leukemic cells from the heavily exposed patients contained persistent cellular genetic instability which may strongly influence the development of leukemia in people exposed to radiation. (+info)
Genetic characterization of multifocal tumor growth in renal cell carcinoma.
(23/1355)
The primary cancer found in the kidney is renal cell carcinoma (RCC), which does not as yet have a delineation of the types of lesions that progress to tumor malignancy. We studied tissues from primary tumors and secondary lesions, and compared it with the surrounding normal kidney tissue using comparative genomic hybridization to determine their potential for malignancy. Although our sample size was small, we found that small multifocal tumors have the same potential as primary carcinoma to lead to RCC malignancy. Further genetic studies in a larger sample of patients is necessary before the risk of different lesions to remain benign or progress to RCC can be defined absolutely. (+info)
A novel NE-dlg/SAP102-associated protein, p51-nedasin, related to the amidohydrolase superfamily, interferes with the association between NE-dlg/SAP102 and N-methyl-D-aspartate receptor.
(24/1355)
The membrane-associated guanylate kinase proteins have been known to interact various membrane receptors with their N-terminal segments designated the PDZ domains and to cluster these receptors at the target site of the cell membrane. NE-dlg/SAP102, a neuronal and endocrine tissue-specific MAGUK family protein, was found to be expressed in both dendrites and cell bodies in neuronal cells. Although NE-dlg/SAP102 localized at dendrites was shown to interact with N-methyl-D-aspartate receptor 2B via the PDZ domains to compose postsynaptic density, the binding proteins existing in the cell body of the neuron are still unknown. Here we report the isolation of a novel NE-dlg/SAP102-associated protein, p51-nedasin. Nedasin has a significant homology with amidohydrolase superfamily proteins and shows identical sequences to a recently identified protein that has guanine aminohydrolase activity. Nedasin has four alternative splice variants (S, V1, V2, and V3) that exhibited different C-terminal structures. NE-dlg/SAP102 is shown to interact with only the S form of nedasin which is predominantly expressed in brain. The expression of nedasin in neuronal cells increases in parallel with the progress of synaptogenesis and is mainly detected in cell bodies where it co-localizes with NE-dlg/SAP102. Furthermore, nedasin interferes with the association between NE-dlg/SAP102 and NMDA receptor 2B in vitro. These findings suggest that alternative splicing of nedasin may play a role in the formation and/or structural change in synapses during neuronal development by modifying clustering of neurotransmitter receptors at the synaptic sites. (+info)