Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “CHROMOSOMES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,297 records · Page 72Linked to original sources
PubMed1987

The gene encoding the epsilon subunit of the T3/T-cell receptor complex maps to chromosome 11 in humans and to chromosome 9 in mice.

The T3 complex is composed of three polypeptide chains that are both structurally and functionally associated with the receptor for antigen on the surface of human T lymphocytes. In a series of experiments utilizing both somatic cell hybrids and chromosomal hybridization in situ, the genes encoding two members of the human T3 complex, T3-delta and T3-epsilon, were found to reside on the long arm of chromosome 11 in band q23. The murine T3-epsilon gene was localized to chromosome 9. The location of the T3-delta and T3-epsilon genes with respect to the Hu-ets-1 gene, which is also located in 11q23, is discussed. Recent assignments of several genes, preferentially expressed in human cells of hematopoietic and neuroectodermal origins, to band q23 of human chromosome 11 and the murine equivalents to murine chromosome 9 may define a conserved gene cluster important in cell proliferation and differentiation.

Animals↗
PubMed2000

Higher-order structure of interphase chromosomes and radiation-induced chromosomal exchange aberrations.

PURPOSE: To discuss the effects of chromosome structure on the inter- and intrachromosomal exchanges in the framework of the model, which argues that the higher-order chromosome structure contains 10-30 Mbp loop clusters (micelles). RESULTS AND CONCLUSIONS: Intermicelle contacts determine exchange-type chromosome aberrations. Ratios of inter- to intrachromosomal exchanges calculated in the model are similar to the experimental data (literature) for human lymphocytes and flat fibroblasts. The frequency of interchanges is affected by nuclear shape; this might explain the greater number of interchanges observed in 3-D spherical lymphocytes vs. that in 2-D flat fibroblasts. Chromosome configuration (linear vs. folded Rab1) affects the pattern of micelle contacts. The model predicts that chromosomes in haploid Tradescantia microspores have the folded Rab1 orientation; this explains quantitatively the low value of the ratio of dicentrics to centric rings observed in these cells.

Chromosome Aberrations↗
PubMed1992

Heavy ion-induced chromosome breakage studied by premature chromosome condensation (PCC) in Syrian hamster embryo cells.

We have studied induction and repair of chromosome damage induced by high linear energy transfer (LET) heavy ions in G1/G0 interphase Syrian golden hamster embryo (SHE) cells as revealed by the premature chromosome condensation (PCC) technique. The number of chromosome breaks in condensed chromosomes induced by high LET heavy ions was higher than those induced by 137Cs gamma-rays. Compared with 137Cs gamma rays, the relative biological effectiveness (RBE) for PCC breaks was 1.5 for 35 keV/microns 4He ions, 1.9 for 77keV/microns 4He ions, and 2.5 for 530keV/microns 14N ions. Although 95% of the PCC breaks induced by gamma-rays rejoined during 8 h post-irradiation incubation, only 35-45% of fragments induced by high LET radiations rejoined in the same time. These results suggest that there is a difference, spatial or qualitative, in the initial chromosome damage produced by high LET radiations and low LET radiations.

Animals↗
PubMed1998

Combined use of chromosome painting and telomere detection to analyse radiation-induced chromosomal aberrations in mouse splenocytes.

PURPOSE: Analysis of chromosomal aberrations by fluorescence in situ hybridization using a combination of chromosome painting and telomere detection in order to get more insight into: (a) the extent of incompleteness of exchanges and (b) the frequencies of interstitial fragments. MATERIALS AND METHODS: Isolated mouse splenocytes were exposed in vitro to X-rays at a dose of 2 Gy. Aberrations involving chromosomes 2 and 3 were analysed by FISH using simultaneous chromosome painting and telomere detection. RESULTS: At 2 Gy, about 10% of apparently simple exchanges are incomplete. A striking observation was the high induction of interstitial fragments, with frequencies nearly as high as that of dicentrics. Assuming, that both ends of all interstitial fragments have rejoined with each other (to form acentric rings), it can be estimated that over 92% of reactive ends of detectable breakpoints have rejoined illegitimately. Overall, equal frequencies of translocation types t(Ab) and t(Ba) (according to the PAINT nomenclature) were observed. Also, the ratios between reciprocal forms of translocations and dicentrics were close to 1 for both the chromosomes studied. CONCLUSIONS: These studies have shown that many of the frequently observed 'one-way' exchanges using painting probes, are in fact reciprocal exchanges with one participating lesion so close to the telomere that no distal signal can be detected. Frequencies of true incomplete exchanges were found to be low. Intrachanges, here detected as interstitial fragments, were observed frequently.

Animals↗
PubMed1986

Localization of the human NCAM gene to band q23 of chromosome 11: the third gene coding for a cell interaction molecule mapped to the distal portion of the long arm of chromosome 11.

cDNA clones containing sequences coding for the murine neural cell adhesion molecule (N-CAM) were used in Southern hybridizations on human genomic DNA and demonstrated approximately 90% homology between human and murine NCAM genes. In situ hybridization with one of these clones was performed on human metaphase chromosomes and allowed the localization of the human NCAM gene to band q23 of chromosome 11. The genes for two other cell surface molecules believed to be involved in cell-cell interactions, Thy-1 and the delta chain of the T3-T cell receptor complex, have recently been localized to the same region of chromosome 11 in man. Moreover, this region of the human chromosome 11 appears to be syntenic to a region of murine chromosome 9 that also contains the staggerer locus: staggerer mice show abnormal neurological features which may be related to abnormalities in the conversion of the embryonic to the adult forms of the N-CAM molecule.

Animals↗
PubMed1977

Complement-mediated antiserum cytotoxic reactions to human chromosome 7 coded antigen(s): immunoselection of rearranged human chromosome 7 in human-mouse somatic cell hybrids.

Immunoselection via complement-dependent lysis of human-mouse somatic cell hybrids containing chromosome 7, with antisera reactive to cell surface antigen(s) coded for by chromosome 7, has resulted in growth of somatic cell hybrids containing rearranged human chromosome 7s. Investigation of these hybrids has localized the gene(s) coding for the relevant cell surface antigen(s) to the short arm of human chromosome 7. The simian virus 40 integration site and the gene coding for human beta-glucuronidase appear to be localized to the long arm of chromosome 7 in this hybrid clone.

Animals↗
PubMed1997

Genetic mapping using microcell-mediated chromosome transfer suggests a locus for Nijmegen breakage syndrome at chromosome 8q21-24.

Nijmegen breakage syndrome (NBS) is an autosomal recessive disorder characterized by microcephaly, short stature, immunodeficiency, and a high incidence of cancer. Cultured cells from NBS show chromosome instability, an increased sensitivity to radiation-induced cell killing, and an abnormal cell-cycle regulation after irradiation. Hitherto, patients with NBS have been divided into the two complementation groups V1 and V2, on the basis of restoration of radioresistant DNA synthesis, suggesting that each group arises from a different gene. However, the presence of genetic heterogeneity in NBS has been considered to be controversial. To localize the NBS gene, we have performed functional complementation assays using somatic cell fusion between NBS-V1 and NBS-V2 cells, on the basis of hyper-radiosensitivity, and then have performed a genomewide search for the NBS locus, using microcell-mediated chromosome transfer followed by complementation assays based on radiosensitivity. We found that radiation resistance was not restored in the fused NBS-V1 and NBS-V2 cells and that only human chromosome 8 complements the sensitivity to ionizing radiation, in NBS cell lines. In complementation assays performed after the transfer of a reduced chromosome, merely the long arm of chromosome 8 was sufficient for restoring the defect. Our results strongly suggest that NBS is a homogeneous disorder and that the gene for NBS is located at 8q21-24.

Abnormalities, Multiple↗
PubMed2006

The Mcp element mediates stable long-range chromosome-chromosome interactions in Drosophila.

Chromosome organization inside the nucleus is not random but rather is determined by a variety of factors, including interactions between chromosomes and nuclear components such as the nuclear envelope or nuclear matrix. Such interactions may be critical for proper nuclear organization, chromosome partitioning during cell division, and gene regulation. An important, but poorly documented subset, includes interactions between specific chromosomal regions. Interactions of this type are thought to be involved in long-range promoter regulation by distant enhancers or locus control regions and may underlie phenomena such as transvection. Here, we used an in vivo microscopy assay based on Lac Repressor/operator recognition to show that Mcp, a polycomb response element from the Drosophila bithorax complex, is able to mediate physical interaction between remote chromosomal regions. These interactions are tissue specific, can take place between multiple Mcp elements, and seem to be stable once established. We speculate that this ability to interact may be part of the mechanism through which Mcp mediates its regulatory function in the bithorax complex.

ATP-Binding Cassette Transporters↗
PubMed1988

X chromosome duplications affect a region of the chromosome they do not duplicate in Caenorhabditis elegans.

X chromosome duplications have been used previously to vary the dose of specific regions of the X chromosome to study dosage compensation and sex determination in Caenorhabditis elegans. We show here that duplications suppress and X-linked hypomorphic mutation and elevate the level of activity of an X-linked enzyme, although these two genes are located in a region of the X chromosome that is not duplicated. The effects do not depend on the region of the X chromosome duplicated and is stronger in strains with two doses of a duplication than in strains with one dose. This is evidence for a general elevation of X-linked gene expression in strains carrying X-chromosome duplications, consistent with the hypothesis that the duplications titrate a repressor acting on many X-linked genes.

Acetylcholinesterase↗
PubMed2000

Comparative fluorescence in situ hybridization mapping of a 431-kb Arabidopsis thaliana bacterial artificial chromosome contig reveals the role of chromosomal duplications in the expansion of the Brassica rapa genome.

Comparative genome studies are important contributors to our understanding of genome evolution. Most comparative genome studies in plants have been based on genetic mapping of homologous DNA loci in different genomes. Large-scale comparative physical mapping has been hindered by the lack of efficient and affordable techniques. We report here the adaptation of fluorescence in situ hybridization (FISH) techniques for comparative physical mapping between Arabidopsis thaliana and Brassica rapa. A set of six bacterial artificial chromosomes (BACs) representing a 431-kb contiguous region of chromosome 2 of A. thaliana was mapped on both chromosomes and DNA fibers of B. rapa. This DNA fragment has a single location in the A. thaliana genome, but hybridized to four to six B. rapa chromosomes, indicating multiple duplications in the B. rapa genome. The sizes of the fiber-FISH signals from the same BACs were not longer in B. rapa than those in A. thaliana, suggesting that this genomic region is duplicated but not expanded in the B. rapa genome. The comparative fiber-FISH mapping results support that chromosomal duplications, rather than regional expansion due to accumulation of repetitive sequences in the intergenic regions, played the major role in the evolution of the B. rapa genome.

Arabidopsis↗
PubMed1972

The addition of lac+ chromosome fragments to the E. coli proA-proB-lac deletion 13 chromosome.

Escherichia coli with the proA-proB-lac deletion X111 (Delta111) can be transduced with bacteriophage P1 propagated on a wild-type lac(+) donor. Though the donor lac(+) genes cannot be integrated by replacement of the recipient Delta111 marker, the transduction process has the characteristics generally associated with generalized transduction of bacterial genes. Transduction does not require P1 helper infection, is stimulated by UV irradiation of transducing particles, and does require homology between the donor lac(+) chromosome and the recipient Delta111 chromosome. Among transductants produced through multiple P1 infection, a minority of P1dl lysogens are present. But the majority of the transductants have unstable lac(+) units, designated lacV, which are without detected P1 gene content. LacV is tightly linked to the Delta111 locus. Instability of lac(+) is eliminated when a recombination deficiency is introduced through a substitution of recA1 for rec(+). The properties of the Delta111/lacV strains are attributable to a chromosome in which lac(+) is situated between units of a genetic duplication beside the Delta111 locus. To explain the formation of partially diploid chromosomes we suggest that chromosome fragment integration is sometimes accomplished through a single aberrant recombination, a fusion of genetically heterologous DNA ends, and a single legitimate crossover.

Chromosome Aberrations↗
PubMed1994

Molecular characterization of a novel human gene, SEC13R, related to the yeast secretory pathway gene SEC13, and mapping to a conserved linkage group on human chromosome 3p24-p25 and mouse chromosome 6.

We previously described sequence tags from 58 novel directionally cloned human cDNAs from an enriched retinal pigment epithelial cell line library (Gieser and Swaroop, 1992). The nucleotide sequence of one of the cDNA clones, AA35 (D3S1231E), showed strong homology to the yeast SEC13 gene, required for vesicle biogenesis from endoplasmic reticulum during the transport of proteins. We have designated the human gene SEC13R (SEC13-Related). The amino acid sequence of the SEC13R gene product shows 70% similarity to yeast Sec13p, suggesting that SEC13R may be the human homolog of SEC13. The deduced polypeptide sequence contains several beta-transducin like 'WD40' repeats, and is rich in serine and threonine residues. The 1.4 kb transcript of SEC13R is detected by Northern analysis in many human tissues. However, RT-PCR analysis using two primer sets from different regions of the gene suggests differential expression of alternately spliced transcripts in various tissues. Somatic cell hybrid and in situ hybridization studies localized the SEC13R gene to human chromosome 3p24-p25. A related sequence was mapped to chromosome 18q11.2-q12. SEC13R was physically mapped to a yeast artificial chromosome (YAC) clone spanning the D3S720 marker from the region of the Von Hippel-Lindau disease locus. The mouse Sec13r gene was mapped to the conserved linkage group on chromosome 6 that corresponds to human chromosome 3p24-p25.

Amino Acid Sequence↗
PubMed2000

Major factors influencing linkage disequilibrium by analysis of different chromosome regions in distinct populations: demography, chromosome recombination frequency and selection.

Linkage disequilibrium (LD) mapping of disease genes is complicated by population- and chromosome-region-specific factors. We have analysed demographic factors by contrasting intermarker LD results obtained in a large cosmopolitan population (UK), a large genetic isolate (Sardinia) and a subisolate (village of Gavoi) for two regions of the X chromosome. A dramatic increase of LD was found in the subisolate. Demographic history of populations therefore influences LD. Chromosome-region-specific effects, namely the pattern and frequency of homologous recombination, were next delineated by the analysis of chromosome 6p21, including the HLA region. Patterns of global LD in this region were very similar in the UK and Sardinian populations despite their entirely distinct demographies, and correlate well with the pattern of recombinations. Nevertheless, haplotypes extend across recombination hot spots indicative of selection of certain haplotypes. Subisolate aside, chromosome-region-specific differences in LD patterns appear to be more important than the differences in intermarker LD between distinct populations.

Chromosomes, Human, Pair 6↗
PubMed1988

Chromosome analysis of human oocytes and embryos: does delayed fertilization increase chromosome imbalance?

Thirty per cent of a sample of 120 unfertilized human oocytes carried chromosome abnormalities highly correlated with maternal age (38% in patients greater than 35, as compared with 24% in younger patients). Fertilized eggs, when observed 17 h after insemination, showed in 1.6% a single pronucleus suggesting parthenogenetic activation. In 92% of the cases two pronuclei were observed and the rate of chromosome anomalies depended on the morphological aspect of the embryos. Triploidy was also encountered in 6.4% of the eggs leading to an overall rate of chromosome aberrations reaching 29.2%. Delayed fertilization drastically increased the rate of chromosome anomalies (87%) as well as the rate of mosaicism: 30% versus 10.6% in timely fertilized eggs. The high rate of chromosome disorders in early life after in-vitro fertilization (IVF) raises the ethical question of the opportunity of carrying out a genetic control of normality in human embryos at the preimplantation stage.

Chromosome Aberrations↗
PubMed2001

The gene orders on human chromosome 15 and chicken chromosome 10 reveal multiple inter- and intrachromosomal rearrangements.

Comparative mapping between the human and chicken genomes has revealed a striking conservation of synteny between the genomes of these two species, but the results have been based on low-resolution comparative maps. To address this conserved synteny in much more detail, a high-resolution human-chicken comparative map was constructed from human chromosome 15. Mapping, sequencing, and ordering of specific chicken bacterial artificial chromosomes has improved the comparative map of chromosome 15 (Hsa15) and the homologous regions in chicken with almost 100 new genes and/or expressed sequence tags. A comparison of Hsa15 with chicken identified seven conserved chromosomal segments between the two species. In chicken, these were on chromosome 1 (Gga1; two segments), Gga5 (two segments), and Gga10 (three segments). Although four conserved segments were also observed between Hsa15 and mouse, only one of the underlying rearrangement breakpoints was located at the same position as in chicken, indicating that the rearrangements generating the other three breakpoints occurred after the divergence of the rodent and the primate lineages. A high-resolution comparison of Gga10 with Hsa15 identified 19 conserved blocks, indicating the presence of at least 16 intrachromosomal rearrangement breakpoints in the bird lineage after the separation of birds and mammals. These results improve our knowledge of the evolution and dynamics of the vertebrate genomes and will aid in the clarification of the mechanisms that underlie the differentiation between the vertebrate species.

Animals↗
PubMed2003

Meiotic double-strand breaks at the interface of chromosome movement, chromosome remodeling, and reductional division.

Chromosomal processes related to formation and function of meiotic chiasmata have been analyzed in Sordaria macrospora. Double-strand breaks (DSBs), programmed or gamma-rays-induced, are found to promote four major events beyond recombination and accompanying synaptonemal complex formation: (1) juxtaposition of homologs from long-distance interactions to close presynaptic coalignment at midleptotene; (2) structural destabilization of chromosomes at leptotene/zygotene, including sister axis separation and fracturing, as revealed in a mutant altered in the conserved, axis-associated cohesin-related protein Spo76/Pds5p; (3) exit from the bouquet stage, with accompanying global chromosome movements, at zygotene/pachytene (bouquet stage exit is further found to be a cell-wide regulatory transition and DSB transesterase Spo11p is suggested to have a new noncatalytic role in this transition); (4) normal occurrence of both meiotic divisions, including normal sister separation. Functional interactions between DSBs and the spo76-1 mutation suggest that Spo76/Pds5p opposes local destabilization of axes at developing chiasma sites and raise the possibility of a regulatory mechanism that directly monitors the presence of chiasmata at metaphase I. Local chromosome remodeling at DSB sites appears to trigger an entire cascade of chromosome movements, morphogenetic changes, and regulatory effects that are superimposed upon a foundation of DSB-independent processes.

Chromatin↗
PubMed1996

Small extra ring chromosome derived from chromosome 10p: clinical report and characterisation by FISH.

We present a case with a small extra ring chromosome which was found in 66% of lymphocytes on routine cytogenetic examination. FISH analyses, using centromere specific and single copy probes, showed that the extra ring chromosome was derived from the most proximal part of 10p, close to the centromere. The patient has a unilateral cleft lip and palate, mild dysmorphic features, and mild mental retardation. Only a limited number of extra ring chromosomes have been characterised so far. To our knowledge, this is the first reported patient with an extra ring chromosome derived from chromosome 10p.

Abnormalities, Multiple↗
PubMed2001

Analysis of chromosomal aberrations involving chromosome 1q31-->q53 in a DMBA-induced rat fibrosarcoma cell line: amplification and overexpression of Jak2.

In a study of DMBA-induced rat fibrosarcomas we repeatedly found deletions and/or amplifications in the long arm of rat chromosome 1 (RNO1). Comparative genome hybridization showed that there was amplification involving RNO1q31-->q53 in one of the DMBA-induced rat fibrosarcoma tumors (LB31) and a cell culture derived from it. To identify the amplified genes we physically mapped rat genes implicated in cancer and analyzed them for signs of amplification. The genes were selected based on their locations in comparative maps between rat and man. The rat proto-oncogenes Ccnd1, Fgf4, and Fgf3 (HSA11q13.3), were mapped to RNO1q43 by fluorescence in situ hybridization (FISH). The Ems1 gene was mapped by radiation hybrid (RH) mapping to the same rat chromosome region and shown to be situated centromeric to Ccnd1 and Fgf4. In addition, the proto-oncogenes Hras (HSA11p15.5) and Igf1r (HSA15q25-->q26) were mapped to RNO1q43 and RNO1q32 by FISH and Omp (HSA11q13.5) was assigned to RNO1q34. PCR probes for the above genes together with PCR probes for the previously mapped rat genes Bax (RNO1q31) and Jak2 (RNO1q51-->q53) were analyzed for signs of amplification by Southern blot hybridization. Low copy number increases of the Omp and Jak2 genes were detected in the LB31 cell culture. Dual color FISH analysis of tumor cells confirmed that chromosome regions containing Omp and Jak2 were amplified and were situated in long marker chromosomes showing an aberrant banding pattern. The configuration of the signals in the marker chromosomes suggested that they had arisen by a break-fusion-bridge (BFB) mechanism.

9,10-Dimethyl-1,2-benzanthracene↗