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At least 811 records · Page 45Linked to original sources
PubMed1998

Characterization of gene expression, genomic structure, and chromosomal localization of Hells (Lsh).

Hells (Lsh) is a lymphoid-specific presumptive helicase with highest expression in lymphoid precursor cells. Other members of the helicase family participate in maintenance of genome stability, DNA repair, and transcriptional control. Here we report the structure and chromosomal location of the Hells gene. The open reading frame of the murine Hells gene spans at least 26.6 kb of chromosomal DNA and is composed of 18 exons. The genomic structure of the seven helicase domains closely resembles that of mammalian Rad54, a gene whose product appears to be involved in recombination and double-strand break repair. The human homologue, the HELLS gene, has a mRNA expression pattern that is similar to murine Hells expression. Low-stringency hybridization in a Southern analysis reveals homologous Hells genes in a variety of species including Saccharomyces cerevisiae. FISH analysis maps the murine Hells gene to region C3-D1 on chromosome 19. The human homologue maps to a region of synteny on chromosome 10q23-q24, a breakpoint region frequently involved in human leukemia.

Animals↗
PubMed1995

Rearrangement of chromosome 1 is a frequent finding in endometrial carcinoma. An in situ hybridization study in nine endometrial carcinomas.

Nine endometrial carcinomas were examined for numerical aberrations of the chromosomes 1,7, and X by fluorescence in situ hybridization using highly repetitive chromosome-specific probes. In addition, a combination of a centromeric and a telomeric chromosome 1 probe was applied to detect structural chromosome 1 aberrations. Chromosome aberrations were found in six tumors. In four of these, an imbalance between 1q12 and 1p36 was detected, indicating the presence of an extra 1p- chromosome. In regard to the chromosomes 7 and X, monosomies and trisomies were found. Intratumoral genetic heterogeneity in endometrial carcinomas was detectable by FISH and flow cytometry. In conclusion, our findings confirm that chromosome 1 is frequently involved in structural chromosome changes, indicating chromosome 1 to be of importance in the evolution of endometrial carcinoma.

Adenocarcinoma↗
PubMed2006

Condensin and Repo-Man-PP1 co-operate in the regulation of chromosome architecture during mitosis.

The reversible condensation of chromosomes during cell division remains a classic problem in cell biology. Condensation requires the condensin complex in certain experimental systems, but not in many others. Anaphase chromosome segregation almost always fails in condensin-depleted cells, leading to the formation of prominent chromatin bridges and cytokinesis failure. Here, live-cell analysis of chicken DT40 cells bearing a conditional knockout of condensin subunit SMC2 revealed that condensin-depleted chromosomes abruptly lose their compact architecture during anaphase and form massive chromatin bridges. The compact chromosome structure can be preserved and anaphase chromosome segregation rescued by preventing the targeting subunit Repo-Man from recruiting protein phosphatase 1 (PP1) to chromatin at anaphase onset. This study identifies an activity critical for mitotic chromosome structure that is inactivated by Repo-Man-PP1 during anaphase. This activity, provisionally termed 'regulator of chromosome architecture' (RCA), cooperates with condensin to preserve the characteristic chromosome architecture during mitosis.

Adenosine Triphosphatases↗
PubMed2003

Arm-specific multicolor fluorescence in situ hybridization reveals widespread chromosomal instability in glioma cell lines.

An investigation of numerical and structural chromosome aberrations using chromosome arm-specific multicolor fluorescence in situ hybridization (armFISH) revealed considerable genetic heterogeneity among and within 11 glioma cell lines. Despite the substantial variation in numerical chromosome alterations among the cell lines, several distinct and glioma growth-associated losses or gains were frequently observed, that is, losses of chromosomes 10, 13, and 22 and gain of chromosome 7 in particular. Structural aberrations frequently affected chromosomes 1, 4, 7, 16, and 19; however, no single structural chromosome aberration common to all or even several glioma cell lines could be found. Structural alterations were often multiform, and a large variety of unstable chromosome structures were detected. Two of the cell lines also harbored small marker chromosomes containing mainly heterochromatin and chromosomal insertions within hetero-chromatic regions. Altogether, the armFISH provides a versatile tool for the identification of chromosomal aberrations as well as their formation patterns in tumors with a complex genome at the level of chromosome arms.

Brain Neoplasms↗
PubMed1990

Structure and chromosomal location of the human gene encoding cartilage matrix protein.

Cartilage matrix protein (CMP) is a major component of the extracellular matrix of nonarticular cartilage. The structure and chromosomal location of the human gene encoding CMP was determined by molecular cloning analysis. We used a partial chicken CMP cDNA probe to isolate three overlapping human genomic clones. From one of these clones, a probe containing 2 human CMP exons was isolated and used to map the gene to chromosome 1p35 and to screen a human retina cDNA library. Two overlapping cDNA clones were isolated. The predicted protein sequence of 496 amino acids includes a 22-residue signal peptide and a 474-residue mature protein of Mr 51,344. The human CMP gene and polypeptide are strikingly similar to the chicken CMP gene and polypeptide. Human CMP is 79% identical to chicken CMP and contains two homologous domains separated by an epidermal growth factor-like domain. One potential N-glycosylation site is conserved between the two species. The human CMP gene spans 12 kilobase pairs with 8 exons and 7 introns which are similar in size to those of the chicken CMP gene. Both RNA splice junctions of intron G in the human and chicken CMP genes are nonconforming to the consensus splice sequences. This suggests that the CMP gene utilizes a new RNA splicing mechanism.

Amino Acid Sequence↗
PubMed2005

Chromosomal instability in amniocytes from fetuses of mothers who smoke.

CONTEXT: Tobacco increases the risk of systemic diseases, and it has adverse effects on pregnancy. However, only indirect data have been published on a possible genotoxic effect on pregnancy in humans. OBJECTIVES: To determine whether maternal smoking has a genotoxic effect on amniotic cells, expressed as an increased chromosomal instability, and to analyze whether any chromosomal regions are especially affected by exposure to tobacco. DESIGN, SETTING, AND PATIENTS: In this prospective study, amniocytes were obtained by routine amniocentesis for prenatal diagnosis from 25 controls and 25 women who smoke (> or =10 cigarettes/d for > or =10 years), who were asked to fill out a smoking questionnaire concerning their smoking habits. Chromosomal instability was analyzed in blinded fashion by 2 independent observers in routine chromosome spreads. Breakpoints implicated in chromosomal abnormalities were identified by G-banding. MAIN OUTCOME MEASURES: Association between maternal smoking and increased chromosomal instability in amniotic fluid cells, expressed as chromosomal lesions (gaps and breaks) and structural chromosomal abnormalities. RESULTS: Comparison of cytogenetic data between smokers and nonsmokers (controls) showed important differences for the proportion of structural chromosomal abnormalities (smokers: 12.1% [96/793]; controls: 3.5% [26/752]; P = .002) and to a lesser degree for the proportion of metaphases with chromosomal instability (smokers: 10.5% [262/2492]; controls: 8.0% [210/2637]; P = .04), and for the proportion of chromosomal lesions (smokers: 15.7% [391/2492]; controls: 10.1% [267/2637]; P = .045). Statistical analysis of the 689 breakpoints detected showed that band 11q23, which is a band commonly implicated in hematopoietic malignancies, was the chromosomal region most affected by tobacco. CONCLUSIONS: Our findings show that smoking 10 or more cigarettes per day for at least 10 years and during pregnancy is associated with increased chromosomal instability in amniocytes. Band 11q23, known to be involved in leukemogenesis, seems especially sensitive to genotoxic compounds contained in tobacco.

Adult↗
PubMed2005

The structure and function of the bacterial chromosome.

Advances in microscopic and cell biological techniques have considerably improved our understanding of bacterial chromosome organization and dynamics. The nucleoid was formerly perceived to be an amorphous entity divided into ill-defined domains of supercoiling that are randomly deposited in the cell. Recent work, however, has demonstrated a remarkable degree of spatial organization. A highly ordered chromosome structure, established while DNA replication and partitioning are in progress, is maintained and propagated during growth. Duplication of the chromosome and partitioning of the newly generated daughter strands are interwoven processes driven by the dynamic interplay between the synthesis, segregation and condensation of DNA. These events are intimately coupled with the bacterial cell cycle and exhibit a previously unanticipated complexity reminiscent of eukaryotic systems.

Bacteria↗
PubMed1989

X-ray-induced specific-locus mutations in the ad-3 region of two-component heterokaryons of Neurospora crassa. II. More extensive genetic tests reveal an unexpectedly high frequency of multiple-locus mutations.

More extensive genetic tests have been performed on a series of 832 X-ray-induced specific-locus mutations in the ad-3 region of a 2-component heterokaryon (H-12) of Neurospora crassa, reported earlier (Webber and de Serres 1965). Using new tester strains and techniques for performing large-scale genetic tests (heterokaryon, dikaryon and trikaryon) to characterize ad-3 mutants induced in 2-component heterokaryons, new data have been obtained on this sample of X-ray-induced ad-3 mutants. These new data show that unexpectedly high frequencies of both single-locus (gene/point) mutations and multilocus deletions in the ad-3 region have additional, but separate, sites of recessive lethal (RLCL) damage in the immediately adjacent genetic regions. The frequencies of these X-ray-induced multiple-locus mutants in the ad-3 region are orders of magnitude higher than expected on the basis of target theory and classical models of chromosome structure during interphase. Current models of interphase chromosome structure in higher eukaryotes as revealed by chromosome "painting" offer a possible explanation of the Neurospora data.

Adenine↗
PubMed1996

Structure and chromosomal assignment of the murine sterol carrier protein 2 gene (Scp2) and two related pseudogenes by in situ hybridization.

The murine sterol carrier protein 2 gene (Scp2) has been mapped to chromosome 4C5-->D1 by in situ hybridization. This location is syntenic with the locus of SCP2 on human chromosome 1p32. We found the overall structure of murine Scp2 to be identical to that of the human SCP2 gene. In addition, two Scp2 pseudogenes have been isolated and mapped to chromosomes 3H2-->4 and 9F.

Animals↗
PubMed2006

Characterization of rearrangements involving 4q, 13q and 16q in hepatocellular carcinoma cell lines using region-specific multiplex-FISH probes.

Deletions in 4q, 13q and 16q were frequently detected in hepatocellular carcinoma (HCC) by comparative genomic hybridization (CGH) studies. However, detailed chromosome structural aberrations are not fully explored. Using CGH combined with multiplex-color FISH (M-FISH) with chromosome region-specific probes (CRPs), chromosome structural aberrations in 4q, 13q and 16q in six HCC cell lines were studied. All CRPs, which were generated from microdissected DNA, were specific, strong in intensity and sensitive enough to detect chromosome structural aberrations including translocation and deletion. FISH with BAC probes was used to further characterize translocation breakpoints and deletions. A breakpoint at 16q22 was localized at a BAC clone (RP11-341K23) and another breakpoint at 4q28 was localized within a 620 kb-region. A minimal deleted region at 13q21 was found between BAC clones RP11-240M20 and RP11-435P18. This study demonstrated that the combination of CGH, M-FISH and BAC-FISH is a very useful tool to detect and characterize translocation breakpoint.

Carcinoma, Hepatocellular↗
PubMedDate not supplied

[Prognostic value of the chromosome pattern in tumors of the urinary bladder].

Cytodiagnostic and histopathological studies were made in 42 cases of epithelial urinary bladder tumours. The correlation was investigated between the modal chromosomal number, the frequency of the structural chromosomal aberrations and the degree of histologic malignancy (cellular anaplasy and invasion of the bladder wall). The proliferative rate was also determined of the analized tumours. In all the epithelial tumours that have been studied it was noted that the more malignant the tumour, the higher was the value of the modal chromosomal number, and the more frequent the chromosomal abnormalities. The proliferative rate of polyploid tumours was significantly higher as compared with that of the diploid ones. The presence of a polyploid mitotic population, as well as of structural chromosomal disturbances in a tumour with a low degree of malignancy, as demonstrated histologically, may have a prognostic significance.

Carcinoma↗
PubMed1999

Genomic structure and chromosomal mapping of the murine and human Mbd1, Mbd2, Mbd3, and Mbd4 genes.

DNA methylation is essential for murine development and is implicated in the control of gene expression. MeCP2, MBD1, MBD2, MBD3, and MBD4 comprise a family of mammalian, nuclear proteins related by the presence in each of an amino acid motif called the methyl-CpG binding domain (MBD). Each of these proteins, with the exception of MBD3, is capable of binding specifically to methylated DNA. MeCP2, MBD1 and MBD2 can also repress transcription. We describe the genomic structure and chromosomal localization of the human and murine Mbd1, Mbd2, Mbd3, and Mbd4 genes. We find that the highly similar MBD2 and MBD3 proteins are encoded by genes that map to different chromosomes in humans and mice but show a similar genomic structure. The Mbd1 and Mbd2 genes, in contrast, map together to murine and human Chromosomes (Chrs)18. The Mbd3 and Mbd4 genes map to murine Chrs 10 and 6, respectively, while the human MBD3 and MBD4 genes map to Chrs 19 and 3, respectively.

Animals↗
PubMed2000

[High efficient intergeneric chromosomal translocations between wheat (Triticum aestivum L.) and Dasypyrum villosum arising from tissue culture and irradiation].

Intergeneric chromosomal translocations were discernable both in callus cells and in regenerants arising from crosses between Triticum aestivum and T. durum-Dasypyrum villosum amphiploid c.v. TH1 and TH1W by means of fluorescence in situ hybridization. There were not only reciprocal translocations, but small fragment translocations. The results proved again the feasibility of creating intergeneric translocations via tissue culture. Irradiation facilitated numerical and structural chromosome changes in callus cells. The frequency of translocations was as high as 7.4 percent in irradiated callus cells. Callus age had an important impact on numerical and structural chromosome abnormalities. During a given time of culture, the frequency of unchanged cells was declined, while those cells with chromosome losses were inclined. The duration of culture had not significant effects on cells with chromosome gains. As structural chromosome changes is concerned, the duration of culture predominantly increased the frequency of cells with telocentric chromosomes. The chromosomal changes occurred at the initiation period of tissue culture. A number of cells which were doubled their chromosome numbers (2n = 84) were observed at a certain frequency in the period of tissue culture. These cells, however, disappeared in the successive culture.

Crosses, Genetic↗
PubMed1988

SEM of canine chromosomes: normal structure and the effects of whole-body irradiation.

Canine chromosomes are not only numerous (38 autosomal pairs), but they are small (compared to human chromosomes) and morphologically similar as well. Analysis of the canine karyotype by light microscopy (LM) of banded chromosomes is, thus, difficult, and the literature on the canine karyotype is scanty. In this study, we describe examination of chromosomes from normal and chronically irradiated dogs with the scanning electron microscope (SEM). Metaphase chromosomes from bone marrow aspirates were Giemsa-banded with either 0.025% trypsin alone or 0.1% trypsin preceded by 10% H2O2 and prepared for SEM. Examination of chromosomes from normal dogs revealed cylindrical chromosome profiles with well-defined chromatids and centromeres. The chromosome arms were consistently marked by periodic grooves that had complementary structures on sister chromatids and may represent the trypsin-sensitive chromatic regions. The quality of the preservation varied from preparation to preparation and depended on the concentration and time of trypsin treatment. Chromosomes from irradiated dogs revealed translocations, deletions, and gaps. We conclude that SEM produces images superior to LM images of canine chromosomes; SEM images can be used not only to identify individual chromosomes, but also to identify genetic lesions in the chromosomes of chronically irradiated dogs. We further conclude that the two Giemsa-banding protocols used in the present study produced variable results, although 0.025% trypsin alone appeared to give better and more consistent results than 0.1% trypsin preceded by 10% H2O2.

Animals↗
PubMed1991

Gene structure and chromosomal localization of the murine lamin B2 gene.

The structure of the murine lamin B2 gene has been analyzed by cloning, sequencing and hybridization techniques, including in situ hybridization. The gene exists in single copy on the distal arm of chromosome 10 and comprises at least 15 kb, containing 12 exons and 11 introns. The transcriptional start point, as determined by primer extension analysis and RNase protection, was mapped to the region -264 to -254 upstream the ATG start codon. The 5' upstream region does not reveal any classical TATA box elements but typical features of genes encoding "housekeeping" proteins. The intron pattern is strikingly similar to those of the Xenopus laevis lamin LIII (Döring, V., R. Stick, EMBO J. 9, 4073-4081 (1990)) and of the intermediate filament protein of the invertebrate Helix aspersa (Dodemont, H., D. Riemer, K. Weber, EMBO J. 9, 4083-4094 (1990], particularly in the central rod and in the tail domains. Moreover, this lamin gene contains an additional intron in the region encoding the rod domain. Our data are compatible with the evolutionary hypothesis that IF proteins have evolved from a lamin-like ancestor molecule.

Amino Acid Sequence↗
PubMed1999

Nuclear organization of mammalian genomes. Polar chromosome territories build up functionally distinct higher order compartments.

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.

Acetylation↗
PubMed2005

A histone code in meiosis: the histone kinase, NHK-1, is required for proper chromosomal architecture in Drosophila oocytes.

To promote faithful propagation of the genetic material during sexual reproduction, meiotic chromosomes undergo specialized morphological changes that ensure accurate segregation of homologous chromosomes. The molecular mechanisms that establish the meiotic chromosomal structures are largely unknown. We describe a mutation in a recently identified Histone H2A kinase, nhk-1, in Drosophila that leads to female sterility due to defects in the formation of the meiotic chromosomal structures. The metaphase I arrest and the karyosome, a critical prophase I chromosomal structure, require nucleosomal histone kinase-1 (NHK-1) function. The defects are a result of failure to disassemble the synaptonemal complex and to load condensin onto the mutant chromosomes. Embryos laid by nhk-1-/- mutant females arrest with aberrant polar bodies and mitotic spindles, revealing that mitosis is affected as well. We analyzed the role of Histone H2A phosphorylation with respect to the histone code hypothesis and found that it is required for acetylation of Histone H3 and Histone H4 in meiosis. These studies reveal a critical role for histone modifications in chromosome dynamics in meiosis and mitosis.

Animals↗
PubMed1999

Gene structure and chromosomal localization of mouse S-adenosylmethionine decarboxylase.

The structure of the mouse S-adenosylmethionine decarboxylase (AdoMetDC) gene has been determined. The mouse gene (AMD1) consisted of eight exons and seven introns, similar to the rat AdoMetDC gene, and was mapped to chromosome 10. The characteristics of AMD1 gene were as follows: (1) The region of the promoter necessary for maximal transcriptional activity was located about 400 nucleotides upstream of the transcriptional initiation point, and contained a TATA box and two GC boxes. The transcriptional activity of the promoter was nearly equal to that of the SV40 promoter. (2) Two polyadenylation signals for transcription were observed, and the larger AdoMetDC mRNA, which is the dominant form of mRNA, corresponded to mRNA that is generated using the second polyadenylation signal. (3) Using stable transfectants, we confirmed that the upstream open reading frame (uORF) in the 5'-untranslated region (5'-UTR) of AdoMetDC mRNA functioned as a negative regulatory element. Lower concentrations of polyamines affect both stimulation and inhibition of AdoMetDC synthesis, through the uORF in the mRNA, than affect general protein synthesis.

5' Untranslated Regions↗