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 1,765 records · Page 98Linked to original sources
PubMed2005

Aberrancies in the differentiation and maturation of dendritic cells from bone-marrow precursors are linked to various genes on chromosome 4 and other chromosomes of the BB-DP rat.

BB-Diabetes Prone (BB-DP) rats, a model for endocrine autoimmune diseases, are severely lymphopenic, especially lacking ART2+ regulatory T cells. BB-Diabetes Resistant (DR) rats are not lymphopenic and do not develop autoimmunity. BB-DP and BB-DR rats only differ at the lymphopenia (lyp) gene (iddm2) on chromosome 4. Since BB-DP rats also show aberrancies in the differentiation of dendritic cells (DC) from bone-marrow precursors, we tested the hypothesis that F344 rats congenic for a BB-DP chromosome 4 region (42.5-93.6Mb; including the lyp gene, but also iddm4) display an in vitro DC differentiation different from normal F344 rats. Here we show that the 42.5-93.6Mb BB-DP chromosome 4 region is linked to an increased DC precursor apoptosis, a low MHC class II expression, a reduced IL-10 production and a reduced T cell stimulatory capacity of DC. From our previous report on DC differentiation defects in BB rats (only differing in iddm2) and the present report, we deduce that the abnormal apoptosis and low MHC class II expression is linked to iddm2. The reduced T cell stimulatory capacity is linked to other genes on chromosome 4 (candidate gene: iddm4). The reduced IL-10 production has a complex linkage pattern.

Animals↗
PubMed2000

Transposition of duplicated chromosomal segment involving fused BCR-ABL gene or ABL oncogene alone in chronic myelocytic leukemia and Ph chromosome-positive acute leukemia with complex karyotypes.

Thirty-six patients with chronic myelocytic leukemia (CML) in the blastic phase were examined by fluorescence in situ hybridization to clarify the mechanisms of progression of the disease. Two of 19 CML patients in the blastic phase (10.5%) had an extra fused BCR-ABL gene on structurally complex chromosome aberrations in addition to the Ph chromosome. Another patient had an extra ABL oncogene on the end of a deleted chromosome, resulting in three copies of the ABL oncogene. These three patients showed additional chromosome aberrations, such as der(12), der(15), and der(18), which differ from the standard karyotypic evolution in the blastic phase. Amplification of the fused BCR-ABL gene or the ABL oncogene seemed to be induced by transposition. These segmental transpositions suggest that these regions have high genetic instability possibly leading to blastic transformation.

Chromosome Aberrations↗
PubMed2000

Correlation between centromere and chromosome length in human male pronuclear chromosomes: ultrastructural analysis.

Ultrastructural and morphometric analyses of centromeric regions by scanning and transmission electron microscopy have been performed in chromosomes from male pronuclei obtained by heterologous fertilisation of hamster oocytes with human spermatozoa. In 1308 of 1323 chromosomes analysed, the primary constriction showed a defined biconcave constriction of variable length (0.56-1.34 microns) and constant width (0.64-0.7 micron). A positive correlation was observed between centromeric length and chromosome length. In some chromosomes, the primary constriction appears as decondensed regions of variable length (1.6-2.51 microns) composed of chromatin fibres with a minimum diameter of 30 nm.

Animals↗
PubMed1998

Molecular cloning of metaphase chromosome protein 1 (MCP1), a novel human autoantigen that associates with condensed chromosomes during mitosis.

Systemic lupus erythematosus autoantibodies were used to identify and to characterize new human chromosome-associated proteins. Previous immunolocalization studies in human and murine tissue culture cells showed that some of these monoclonal antibodies recognize nuclear antigens that associate with condensed chromosomes during mitosis. One antibody was selected for screening a human HeLa S3 cDNA expression library, and cDNAs that code for an antigen of 31-33 kDa were isolated. Immunological, biochemical and cell fractionation data indicate that the 31- to 33-kDa antigen corresponds to the chromosome-associated protein recognized by the original monoclonal antibody. Sequence analysis shows that we isolated a novel human gene. Immunolocalization to human tissue culture cells shows that during interphase the antigen is dispersed in the nucleus and that during mitosis it associates exclusively with condensed chromosomes. A similar pattern of localization was also observed in mouse fibroblasts, suggesting that the antigen is conserved among different species. Finally, we show that part of the antigen remains bound to the scaffold/matrix component, even after high salt extraction.

Amino Acid Sequence↗
PubMed2005

Forty-two supernumerary marker chromosomes (SMCs) in 43,273 prenatal samples: chromosomal distribution, clinical findings, and UPD studies.

Fluorescence in situ hybridization (FISH) analyses were performed on supernumerary marker chromosomes (SMCs) detected in 43,273 prenatal diagnoses over a period of 11 years, 1993-2003. A total of 42 pregnancies with SMC were identified, indicating a prevalence of one in 1032. A total of 15 SMCs were endowed with detectable euchromatin (prevalence, 1/2884), including six SMCs containing the cat eye critical region (CECR) on chromosome 22q11.21 (1/7212). De novo SMCs were found in 29 pregnancies (1/1492), including 14 euchromatic SMCs (48.2%). Follow-up studies were available for 24 cases. Nine pregnancies (37.5%) were terminated; two children (8.3%) were born with Pallister-Killian syndrome and cat eye syndrome (CES), respectively; 13 children (54.1%) showed apparently normal development. Familial SMCs were identified in 13 pregnancies (1/3328) from 11 unrelated women. They were all acrocentric. In all, 10 were heterochromatic and one was an extra der(22)t(11;22) chromosome. A total of 12 cases were available for follow-up. One pregnancy was terminated due to anhydramnios, spina bifida, and cystic-dysplastic kidneys; one child suffered from a der(22) syndrome; 10 children (83.3%) appeared unaffected. Studies for uniparental disomy were performed on seven pregnancies and revealed a case of maternal heterodisomy for chromosome 22. So far this is the largest FISH study of prenatally ascertained SMCs and the first study with detailed data on the prevalence. Findings illustrate the spectrum and clinical outcomes of prenatally diagnosed SMCs, and indicate a higher frequency of SMCs than generally assumed.

Abnormalities, Multiple↗
PubMed1991

Sex reversing non-disjunction of the Y chromosome produces exceptionally low sex ratio (% males) and hermaphrodites in the progeny of male BALB/cBm mice: the roles of the maternal genotype and the Y chromosome.

When females of 21 strains and hybrids were mated to BALB/cBm males to determine the role of the maternal genome in the sex reversing non-disjunction of the Y chromosome, (1) BALB/cBm and BALB/cBy and SJL/J females produced 39.5-41.5% males and 2.4-2.8% hermaphrodites; (2) SWR/J, A/HeJ, DBA/2J and C3HeB/FeJ produced 44.8-49.1% males and 0.2-0.7% hermaphrodites; (3) C3H/HeJ and three strains of C57BL produced normal sex ratios and no hermaphrodites; (4) four F1 hybrids produced 44.5-49.2% males and 0.3-1.9% hermaphrodites; (5) the seven CXB RI strains produced perplexing sets of data: 26.5%-52.0% males and 0.2-3.2% hermaphrodites. These results indicate that a partly dominant gene favouring non-disjunction occurs in the female genomes of BALB/c and SJL/J strains, an enhancing gene occurs in C57BL/6By and there may be others. Heterosis appears to favour normal mitosis. CXBH females produced 26.5% males and 3.2% hermaphrodites, indicating that non-disjunction may have occurred in every male zygote, thus providing models for the generation of Turner's syndrome, hermaphroditism and a predictable non-disjunction. Reciprocal crosses were made between SJL/J and BALB/cBm, followed by 20 backcrosses to the maternal strains, to exchange the Ys and produce two new consomic strains. Males from SJL-BALB/cBm-Y strain, when mated to CXBH females, sired 34.3% males and 4.3% hermaphrodites, whereas BALB/cBm-SJL-Y sired no hermaphrodites and the sex ratio of the offspring was normal. This shows that the non-disjunction involves only the BALB/cBm Y chromosome and is completely independent of genes on the X or autosomal chromosomes. These results indicate that the BALB/cBm Y chromosome is unable to interact normally with the mitotic spindles of some genotypes, particularly CXBH, BALB/c and SJL. The simplest hypothesis is that a primary non-disjunction occurs at first cleavage. This can produce an array of mosaics determined by chance in the many sampling events that take place during development and by the relative vigour and stability of the two original clones.

Animals↗
PubMed1992

Parental imprinting studied by allele-specific primer extension after PCR: paternal X chromosome-linked genes are transcribed prior to preferential paternal X chromosome inactivation.

The preferential inactivation of the paternal X chromosome in extraembryonic cells during early mouse development is an example of parental imprinting, but it has not been studied at the transcriptional level because standard methods of measuring RNA levels do not allow detection of allele-specific RNAs in individual early embryos. We sought to determine whether the paternal allele of the X chromosome-linked gene for 3-phosphoglycerate kinase 1 (Pgk-1), which is located very near the center of X chromosome inactivation, is transcribed prior to differentiation of extraembryonic lineages. Previous reports indicated that in heterozygous embryos there is a delay in the appearance of the phosphoglycerate kinase 1 allozyme encoded by the paternal X chromosome until 2 days after the appearance of the corresponding maternal allozyme. We report results obtained by use of a reverse transcription/PCR-based method which allows the quantitative measurement of allele-specific RNA. The assay is sensitive enough for the quantitative analysis in single embryos of allele-specific transcripts differing by only one nucleotide. We have used this assay to analyze mouse embryos heterozygous at the Pgk-1 and Hprt [hypoxanthine (guanine) phosphoribosyltransferase] loci, and we find that individual 8-cell and blastocyst embryos express both Hprt and Pgk-1 paternal transcripts, as do pooled 2- to 4-cell embryos. These results are discussed in view of the apparent temporal delay in paternal expression of the Pgk-1 gene at the enzyme level.

Alleles↗
PubMed1996

Chromosomal localization of the proteasome Z subunit gene reveals an ancient chromosomal duplication involving the major histocompatibility complex.

Proteasomes are the multi-subunit protease thought to play a key role in the generation of peptides presented by major histocompatibility complex (MHC) class I molecules. When cells are stimulated with interferon gamma, two MHC-encoded subunits, low molecular mass polypeptide (LMP) 2 and LMP7, and the MECL1 subunit encoded outside the MHC are incorporated into the proteasomal complex, presumably by displacing the housekeeping subunits designated Y, X, and Z, respectively. These changes in the subunit composition appear to facilitate class I-mediated antigen presentation, presumably by altering the cleavage specificities of the proteasome. Here we show that the mouse gene encoding the Z subunit (Psmb7) maps to the paracentromeric region of chromosome 2. Inspection of the mouse loci adjacent to the Psmb7 locus provides evidence that the paracentromeric region of chromosome 2 and the MHC region on chromosome 17 most likely arose as a result of a duplication that took place at an early stage of vertebrate evolution. The traces of this duplication are also evident in the homologous human chromosome regions (6p21.3 and 9q33-q34). These observations have implications in understanding the genomic organization of the present-day MHC and offer insights into the origin of the MHC.

Amino Acid Sequence↗
PubMed1978

Chromosome condensation and radiation-induced G2 arrest studied by the induction of premature chromosome condensation following cell fusion.

When mitotic and interphase cells are fused together, the chromosomes of the interphase cell sometimes condense prematurely. The phenomenon of premature chromosome condensation (PCC) was utilized in investigating the problem of whether the chromosomes of cells suffering a radiation-induced G2 delay are capable of condensation. Colcemide-arrested mitotic cells were fused with synchronized G2 cells, and with irradiated cells suffering a G2 delay. The frequency of PCC in mitotic X G2 binucleate cells was determined. This was compared to the PCC frequency in an unirradiated synchronized population rich in G2 cells after fusion with mitotic cells. Flash-labelling with 3HTdR and autoradiography allowed us to eliminate S-phase cells. The frequency of G2 PCCs was not significantly different for the irradiated G2-delayed or unirradiated cells. From these results we conclude that the chromosomes of cells suffering a G2 arrest are capable of condensation, although the involvement of the condensation process in radiation-induced G2 delay cannot be ruled out.

Cell Cycle↗
PubMed1999

Clustering of radiation-produced breaks along chromosomes: modelling the effects on chromosome aberrations.

PURPOSE: For high-LET radiations, and perhaps even for hard X-rays, DNA double-strand breaks (dsb) are clustered nonrandomly along chromosomes; disproportionately, many inter-dsb segments are less than a few Mbp (10(6) base pairs). The implications of such dsb clustering for chromosome aberrations are analysed. METHODS: Chromosome segments between different dsb within one dsb cluster are assumed too small to detect in the aberration assay. Enumeration or Monte-Carlo computer simulations are used to compute the relative frequencies of many observable aberration patterns: apparently simple or visibly complex. The theoretical predictions are compared with X-ray data for human fibroblasts, involving painted chromosomes 1, 2, 4, 5, 7 or 13. RESULTS AND CONCLUSIONS: Surprisingly, cryptic dsb multiplicity does not affect the frequency ratios predicted for aberration patterns by a random breakage-and-rejoining model. The model is generally consistent with current data on many different types of aberrations, whether or not dsb usually occur in cryptic clusters. For a Revell-type exchange model, however, the predictions do depend on clustering configurations; they gradually approach the predictions of the breakage-and-rejoining model as average cluster multiplicity increases. The model is consistent with the data, for example with the ratio of visibly complex to apparently simple aberrations, only if there is considerable dsb clustering even at low-LET, with approximately 1.5 or more reactive dsb per cluster on average.

Chromosome Aberrations↗
PubMed1969

The DNA base composition of individual chromosomes and chromosome segments from Chironomus tentans.

The base composition of DNA was determined for individual chromosomes from the dipteran Chironomus tentans and for each one of six different segments of one of the chromosomes. The isolations were carried out by micromanipulation and the DNA purines were first extracted from the isolated components and afterwards separated by means of microelectrophoresis on a cellulose fiber. It was found that DNA from this material has an unusual composition corresponding to a guanine + cytosine content of about 30%. This composition was not a function of the polytenic condition but was also found for DNA from testis tissue. Furthermore Drosophila has a more traditional base composition for the bulk of DNA. Statistically significant variations in base data were found between whole chromosomes as well as between the segments from one of the chromosomes.

Adenine↗
PubMed1983

Low angle x-ray diffraction studies of HeLa metaphase chromosomes: effects of histone phosphorylation and chromosome isolation procedure.

To test whether gross changes in chromatin structure occur during the cell cycle, we compared HeLa mitotic metaphase chromosomes and interphase nuclei by low angle x-ray diffraction. Interphase nuclei and metaphase chromosomes differ only in the 30-40-nm packing reflection, but not in the higher angle part of the x-ray diffraction pattern. Our interpretation of these results is that the transition to metaphase affects only the packing of chromatin fibers and not, to the resolution of our method, the internal structure of nucleosomes or the pattern of nucleosome packing within chromatin fibers. In particular, phosphorylation of histones H1 and H3 at mitosis does not affect chromatin fiber structure, since the same x-ray results are obtained whether or not histone dephosphorylation is prevented by isolating metaphase chromosomes in the presence of 5,5'-dithiobis(2-nitrobenzoate) or low concentrations of p-chloromercuriphenylsulfonate (ClHgPhSO3). We also compared metaphase chromosomes isolated by several different published procedures, and found that the isolation procedure can significantly affect the x-ray diffraction pattern. High concentrations of ClHgPhSO3 can also profoundly affect the pattern.

Cell Cycle↗
PubMed1998

Clustering of human chromosome fragments on the mouse genome by chromosome-mediated gene transfer.

Pieces of metaphase chromosomes prepared from mouse cells containing neo-tagged human chromosome 7 were transferred to mouse cells with calcium phosphate to isolate G418-resistant clones. FISH analysis revealed that the majority of them contained human DNA at a single site on their genome. These transformants contained STS markers mapped to various regions of chromosome 7. It is thus suggested that pieces of human chromosomes tend to assemble and integrate on the mouse genome.

Animals↗
PubMed1997

P-element insertion alleles of essential genes on the third chromosome of Drosophila melanogaster: correlation of physical and cytogenetic maps in chromosomal region 86E-87F.

We have established a collection of 2460 lethal or semi-lethal mutant lines using a procedure thought to insert single P elements into vital genes on the third chromosome of Drosophila melanogaster. More than 1200 randomly selected lines were examined by in situ hybridization and 90% found to contain single insertions at sites that mark 89% of all lettered subdivisions of the Bridges' map. A set of chromosomal deficiencies that collectively uncover approximately 25% of the euchromatin of chromosome 3 reveal lethal mutations in 468 lines corresponding to 145 complementation groups. We undertook a detailed analysis of the cytogenetic interval 86E-87F and identified 87 P-element-induced mutations falling into 38 complementation groups, 16 of which correspond to previously known genes. Twenty-one of these 38 complementation groups have at least one allele that has a P-element insertion at a position consistent with the cytogenetics of the locus. We have rescued P elements and flanking chromosomal sequences from the 86E-87F region in 35 lines with either lethal or genetically silent P insertions, and used these as probes to identify cosmids and P1 clones from the Drosophila genome projects. This has tied together the physical and genetic maps and has linked 44 previously identified cosmid contigs into seven "super-contigs" that span the interval. STS data for sequences flanking one side of the P-element insertions in 49 lines has identified insertions in the alphagamma element at 87C, two known transposable elements, and the open reading frames of seven putative single copy genes. These correspond to five known genes in this interval, and two genes identified by the homology of their predicted products to known proteins from other organisms.

Alleles↗
PubMed1978

Reproducible chromosome changes of polycyclic hydrocarbon-induced rat leukemia: incidence and chromosome banding pattern.

Statistical analysis of 361 cases of primary leukemia induced in outbred Long-Evans and Sprague-Dawley rats by 7,12-dimethylbenz[a]anthracene (DMBA) and 7,8,12-trimethylbenz[a]anthracene (TMBA) showed that the incidence of trisomy of chromosome No. 2 was significantly lower with TMBA (17.8%) than with DMBA (29.3%). This tendency was reproducible in both sexes. Another characteristic chromosome abnormality, long No. 2, was found in 10 cases (2.8%). Quinacrine fluorescence analysis revealed that cells with No. 2 trisomy or either of two types of long No. 2 had total and partial No. 2 trisomy, respectively. Other chromosome members of cells with long No. 2, as well as the chromosomes of cells with typical No. 2 trisomy and "normal diploid" leukemia cells, revealed no band abnormality. The phenotype of No. 2 trisomy, severe anemia of the hosts reported in DMBA-induced leukemias, was also noted in leukemias with TMBA-induced No. 2 trisomy but not in leukemias with long No. 2.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1993

Regional base composition variation along yeast chromosome III: evolution of chromosome primary structure.

The recent determination of the complete sequence of chromosome III from the yeast Saccharomyces cerevisiae allows, for the first time, the investigation of the long range primary structure of a eukaryotic chromosome. We have found that, against a background G+C level of about 35%, there are two regions (one in each chromosome arm) in which G+C values rise to over 50%. This effect is seen in silent sites within genes, but not in noncoding intergenic sequences. The variation in G+C content is not related to differential selection of synonymous codons, and probably reflects mutational biases. That the intergenic regions do not exhibit the same phenomenon is particularly interesting, and suggests that they are under substantial constraint. The yeast chromosome may be a model of the structure of the human genome, since there is evidence that it is also a mosaic of long regions of different base compositions, reflected in wide variation of G+C content at silent sites among genes. Two possible causes of this regional effect, replication timing, and recombination frequency, are discussed.

Animals↗
PubMed1999

Population growth of human Y chromosomes: a study of Y chromosome microsatellites.

We use variation at a set of eight human Y chromosome microsatellite loci to investigate the demographic history of the Y chromosome. Instead of assuming a population of constant size, as in most of the previous work on the Y chromosome, we consider a model which permits a period of recent population growth. We show that for most of the populations in our sample this model fits the data far better than a model with no growth. We estimate the demographic parameters of this model for each population and also the time to the most recent common ancestor. Since there is some uncertainty about the details of the microsatellite mutation process, we consider several plausible mutation schemes and estimate the variance in mutation size simultaneously with the demographic parameters of interest. Our finding of a recent common ancestor (probably in the last 120,000 years), coupled with a strong signal of demographic expansion in all populations, suggests either a recent human expansion from a small ancestral population, or natural selection acting on the Y chromosome.

Data Interpretation, Statistical↗
PubMed1985

Chromosomal map of Pseudomonas putida PPN, and a comparison of gene order with the Pseudomonas aeruginosa PAO chromosomal map.

The generalized transducing phage Pf16h2 has been used to confirm linkage relationships of chromosomal markers of Pseudomonas putida previously determined from their time-of-entry in Hfr crosses, and to map new auxotrophic mutations. By means of spot matings using Hfr donors of known origin of transfer, catabolic markers forming part of a closely linked group of operons referred to as a superoperonic cluster have been shown to be chromosomally located and their map positions determined. R-prime-mediated interspecific complementation has been used to equate functionally 21 auxotrophic loci in P. putida and P. aeruginosa, and the distribution of these loci on the two genetic maps has been compared. While both maps reveal that auxotrophic markers are largely restricted to about 40% of the chromosome and that auxotrophic markers of similar phenotype are not clustered, there is evidence of at least seven chromosomal rearrangements since divergence from a presumed common ancestor.

Chromosome Mapping↗