Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Chromosome Structures”

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 865 records · Page 48Linked to original sources
PubMed1984

Evaluation of chemically induced cytogenetic lesions in rabbit oocytes. III. A postimplantation analysis of streptonigrin effects.

The frequency of consistent structural chromosome aberrations was determined for 108 fetuses (day 14 of gestation) from 20 female rabbits treated before conception with 90 micrograms/kg of streptonigrin (NSC-45383). The findings by karyotype analysis of 1.85% of the fetuses with consistent aberrations was compared with 6.32% frequency previously observed in 6-day (preimplantation) blastocysts from identically treated females and found to be significantly reduced. The interpretation of the findings is that the developmental events of implantation and placentation are effective in eliminating from further gestation the majority of the rabbit conceptuses with consistent structural chromosome abnormalities. The data are also discussed relative to the predictive nature of somatic cell chromosome damage in women of childbearing age being an estimator of risk of producing offspring with structural chromosome aberrations. The data show that preconceptional treatment of female rabbits with streptonigrin caused a shift in the cytogenetically determined sex ratio of the 14-day fetuses, but not of the 6-day blastocysts. The significant decrease in relative numbers of males observed is consistent with the induction of lethal mutations on the X chromosome. This finding is discussed in conjunction with the timing and parental specificity of X chromosome inactivation during mammalian embryonic development.

Animals↗
PubMed1980

Chromosome abnormalities in patients with chronic myelocytic leukemia.

Fifty patients with chronic myelocytic leukemia (CML) grouped into four stages on the basis of clinical and hematological results were analyzed with chromosomal banding techniques. Of the 50 patients, 48 hand the "standard" type of Ph1 translocation, t(9 ; 22) (q34 ; q11) and the remaining 2 had Ph1-negative diploid karyotype. The frequency of numerical chromosomal changes and/or structural chromosomal changes other than the Ph1 translocation varied with the stages; the frequency was 1 of 28 cases (3.6%) for patients in stage I (chronic phase), 5 of 11 (45.5%) in stage II (early stage of blastic phase), 11 of 13 (84.6%) in stage III (blastic phase) and 2 of 7 (28.6%) in stage IV (remission phase). Numerical changes in hyperdiploid leukemic cells correlated well with the appearance of extra #8 and extra Ph1 In 5 cases with hypodiploid leukemic cells, one of the #7 pair was absent in 4 cases and Y in 1 case. As structural changes, partial excess of chromosome 1, isochromosome 17q, isochromosome 1q, tdic (20p+ ; 21q-), del (7) (q11), t(2p+ ; 11p-), #12q+ and Xp+ were observed. Chromosomal analysis alone is not the best marker to diagnose the onset of blastic phase; however, it is a useful parameter when considered in combination with clinical and hematological results.

Adult↗
PubMed1986

A comparison of the effect of 5-bromodeoxyuridine substitution on 33258 Hoechst- and DAPI-fluorescence of isolated chromosomes by bivariate flow karyotyping.

Application of the fluorescent DNA-intercalator propidium iodide for stabilization of the mitotic chromosome structure during isolation of chromosomes from V79 Chinese hamster cells and subsequent staining with the fluorochromes 33258 Hoechst or DAPI allowed bivariate flow karyotyping of isolated chromosomes. Fluorescence of 33258 Hoechst bound to isolated chromosomes containing 5-bromodeoxyuridine (BrdUrd) was quenched in comparison with the fluorescence of control chromosomes. Despite structural relationship and similarity of both absorption and fluorescence spectra of DAPI and 33258 Hoechst, reduction of fluorescence of DAPI-stained isolated chromosomes was not observed, by contrast with findings in conventional cytological metaphase preparations. It could be obtained, however, by preirradiation of the chromosomes with near-UV in the presence of DAPI. This led to a progressive destruction of the chromosomes. Destruction also occurred without BrdUrd, though at a slower rate. Preirradiation of chromosomes in the presence of 33258 Hoechst hardly affected the integrity of the chromosomes. Preirradiation of a 33258 Hoechst solution and its subsequent use as a stain resulted in a considerably decreased fluorescence of chromosomes. For DAPI this effect was small. Thus, whereas 33258 Hoechst itself is much more sensitive to near-UV irradiation than DAPI, DAPI bound to DNA in chromosomes renders the DNA much more sensitive to irradiation than 33258 Hoechst bound to DNA. Presumably, these differences can at least partly be reduced to the different molecular sizes of the dyes.

Animals↗
PubMed2000

Sonication per se is not as deleterious to sperm chromosomes as previously inferred.

Although sonication is a simple way to immobilize ("kill") spermatozoa prior to injection into oocytes, this has been thought to be destructive to sperm chromosomes. Mouse and human spermatozoa were immobilized by sonication and kept in various media for up to 2 h, then their nuclei were individually injected into mouse oocytes for the analysis of chromosomes at the first cleavage metaphase. In both the mouse and human, incidence of structural chromosome aberrations was much higher in the spermatozoa sonicated and stored in Biggers-Whitten-Whittingham medium for 2 h at 37.5 degrees C than in those stored for 5 min in the same medium. We concluded, therefore, that it is not sonication per se but a prolonged exposure of sperm nuclei to extracellular milieu that is detrimental to sperm chromosomes. The incidence of structural chromosome aberrations of mouse and human spermatozoa was significantly reduced when the spermatozoa were sonicated and stored in K(+)-rich nucleus isolation medium containing EDTA. This suggests that sperm chromosome degradation following sperm immobilization by sonication is partly due to detrimental effects of a Na(+)-rich medium and of DNase on sperm chromatin. Ideally, it should be possible to prepare artificial media that maintain the integrity of sperm chromosomes for many hours after immobilization.

Animals↗
PubMed1999

Rat osteotesticular phosphatase gene (Esp): genomic structure and chromosome location.

Osteotesticular phosphatase (OST-PTPase) is a class III receptor-type tyrosine phosphatase (RPTPase). It has 10 tandem fibronectin III-like (FN-III) repeats in the extracellular region and two phosphatase domains in the intracellular region. The expression of the rat OST-PTPase gene, Esp, is restricted to osteoblasts and Sertoli cells, and the transcript level in osteoblasts is highly up-regulated by parathyroid hormone and cAMP treatment. We report here the cloning and characterization of the rat Esp gene, including a 2.9-kb 5' flanking region sequence. Two potential binding sites for Osf2/Cbfa1, an osteoblast-specific transcription factor, are present in the promoter. Esp is composed of 35 exons, but spans merely 20 kb, making it the most compact RPTPase gene identified. Each FN-III repeat is encoded by a single exon flanked with phase 1 introns. Two phosphatase domains are encoded by 16 exons in a genomic organization similar to those in RPRPalpha, RPTPgamma, and Ptprc genes. Esp was mapped by fluorescence in situ hybridization to rat chromosome 13q1. These results represent the first genomic structure of a mammalian class III RPTPase gene.

Animals↗
PubMed1993

Structure and chromosomal localization of human insulin-like growth factor-binding protein genes.

The insulin-like growth factor binding proteins (IGFBPs) constitute a structurally related protein family with six known members. We have mapped and regionally localized the genes coding for human IGFBP1, 2, 3, and 4, by in situ hybridization and somatic cell hybrid analysis. The IGFBP2 gene maps to chromosomal region 2q33-q34 whereas the genes for IGFBP1 and 3 are localized in a tail-to-tail fashion on chromosome 7 region p14-p12. The IGFBP4 gene is located in the chromosomal region 17q12-21.1. Structural characterization of the genes coding for IGFBP-1, 2, 3, and 5 showed that the translated parts are divided into four exons. The exons are similar both in size and sequence in all studied genes.

Amino Acid Sequence↗
PubMed2005

Computational analysis and refinement of sequence structure on chromosome 22q11.2 region: application to the development of quantitative real-time PCR assay for clinical diagnosis.

The low-copy repeat (LCR) is a new class of repetitive DNA element and has been implicated in many human disorders, including DiGeorge/velocardiofacial syndrome (DGS/VCFS). It is now recognized that nonallelic homologous recombination (NAHR) through LCRs flanking the chromosome 22q11.2 region leads to genome rearrangements and results in the DGS/VCFS. To refine the structure and content of chromosome 22q11.2 LCRs, we applied computational analysis to dissect region-specific LCRs using publicly available sequences. Nine distinct duplicons between 1.6 and 65 kb long and sharing >95% sequence identity were identified. The presence of these sequence motifs supports the NAHR mechanism. Further sequence analysis suggested that the previously defined 3-Mb deletion may actually comprise two deletion intervals of similar size close to each other and thus indistinguishable when using fluorescence in situ hybridization (FISH) analysis. The differentially deleted regions contain several hypothetical proteins and UniGene clusters and may partially explain the clinical heterogeneity observed in DGS/VCFS patients with the 3-Mb common deletion. To implement further sequence information in molecular medicine, we designed a real-time quantitative PCR assay and validated the method in 122 patients with suspected DGS/VCFS. The assay detected 28 patients with chromosome 22q11.2 deletion later confirmed using FISH. Our results indicated that the developed assay is reliable as well as time and cost effective for clinical diagnosis of chromosome 22q11.2 deletion. They also suggest that this methodology can be applied to develop a molecular approach for clinical detection and diagnosis of other genomic disorders.

Chromosomes, Human, Pair 22↗
PubMed2006

Genotoxic profile of inhibitors of topoisomerases I (camptothecin) and II (etoposide) in a mitotic recombination and sex-chromosome loss somatic eye assay of Drosophila melanogaster.

Genotoxic carcinogens which interact with DNA may produce double-strand breaks as normal intermediates of homologous mitotic recombination, and may give rise to structural chromosome aberrations and inter-chromosomal deletion-recombination. The genotoxic profile of two inhibitors of DNA topoisomerases were evaluated using an in vivo somatic w/w+ eye assay of Drosophila melanogaster for the detection of loss of heterozygosity (LOH) by homologous mitotic recombination, intra-chromosomal recombination and structural chromosomal aberrations. We studied camptothecin (CPT) as a topoisomerase-I-interactive agent and etoposide (ETOP) as a topoisomerase II inhibitor. These drugs act by stabilizing a ternary complex consisting of topoisomerases covalently linked to DNA at single-strand or at double-strand breaks, thereby preventing the relegation step of the breakage/rejoining reaction mediated by the enzyme. The genotoxic profiles were determined from the appearance of eye tissue in adult flies, in which LOH and expression of the reporter gene white produced light clones. The results demonstrated that both compounds were significantly genotoxic, with CPT being more effective than ETOP. Inter-chromosomal mitotic recombination was the major mechanism responsible for the induction of light spots by both compounds in XX females. Loss of the ring X chromosome (rX), was significantly enhanced by CPT, and this topoisomerase blocker also produced intra-chromosomal recombination (XY males).

Animals↗
PubMed2003

Structure of human chromosomes studied by atomic force microscopy. Part II. Relationship between structure and cytogenetic bands.

In the first part of this work, human chromosomes were characterized by atomic force microscopy (AFM) in air and in aqueous solution. The analysis of the images suggests that the last level of organization consists of a radial arrangement of chromatin loops which are anchored to a fiber which is folded giving a pattern of bands which differs in volume. Here the pattern of bands observed by AFM is compared to the cytogenetic map at the 850-band level. Thus thicker and thinner bands are identified as G and R bands, respectively. Finally a model is proposed which links genome sequence, cytogenetics, and chromosome structure.

Chromatids↗
PubMed2004

[Results from 10 years of preimplantation-genetic diagnostics in The Netherlands].

OBJECTIVE: To report the data from couples who were referred for preimplantation-genetic diagnostics (PGD) and treatment due to a significantly increased risk of offspring with a serious genetic disorder. DESIGN: Descriptive, prospective. METHOD: Data were collected from couples that underwent PGD in the period 1993/'03 at Maastricht University Hospital. Embryos produced by means of in-vitro fertilisation (IVF) were subjected to genetic tests several days after fertilisation. Subsequently 1 or 2 unaffected embryos were transferred to the uterus. Where there was an increased risk of a male with an X-linked genetic disorder, the gender was determined using fluorescence in-situ hybridisation (FISH). This method was also used to detect structural chromosomal abnormalities. The polymerase chain reaction (PCR) method was used for mutation detection and/or marker analysis of monogenetic disorders. RESULTS: A total of 691 couples were referred for PGD. The most frequent indications were X-linked disorders (30%), in particular Fragile-X syndrome, Duchenne/Becker muscular dystrophy and haemophilia A/B. This was followed by autosomal dominant disorders (26%), such as Huntington's disease and myotonic dystrophy, and then structural chromosomal abnormalities (24%). A total of 120 women underwent 260 PGD cycles. An embryo transfer was possible in 158 of the cycles and this resulted in 45 successful pregnancies. The pregnancy rate was 17% per cycle initiated and 28% per cycle with embryo transfer. Up until december 2003 29 singletons, 8 sets of twins and 1 set of triplets were born. There were no misdiagnoses and none of the babies had congenital abnormalities. CONCLUSION: PGD was a reliable and successful method, with pregnancy rates similar to those of IVF or intracytoplasmatic sperm injection. PGD should be stated as an alternative during the preconception counselling of couples with an increased genetic risk, especially for disorders where PGD can be routinely applied, such as Huntington's disease, myotonic dystrophy, cystic fibrosis, spinal muscular atrophy, Fragile-X syndrome and structural chromosomal abnormalities.

Adult↗
PubMed1977

Familial occurrence of chromosome variant 17ph+.

A structural chromosome variant 17ph+ was found in a high genetic risk family. The authors consider the possibility of a causal connection between minor structural changes in the karyotype and congenital defects appearing in one member of the family.

Abnormalities, Multiple↗
PubMed1999

Genome structure and chromosomal mapping of the gene for Fe65L2 interacting with Alzheimer's beta-amyloid precursor protein.

Recently we cloned the cDNA encoding human Fe65L2, which interacts with Alzheimer's beta-amyloid precursor protein (APP). The protein has one WW domain and two PID elements (Neurosci. Lett. (1999) 261, 143-146.). Here, we report the entire genome structure and the chromosomal mapping of the Fe65L2 gene. The gene is composed of thirteen coding exons distributed over 6 kb and the genomic organization is similar to another Fe65 member, Fe65 gene. Two transcription start sites of the gene were found in a CpG island by primer extension analysis. Radiation hybrid mapping revealed that the Fe65L2 gene is on chromosome 5 between markers SHGC-9824 (D5S2374) and SHGC-8489 (D5S2569). Characterization of the Fe65L2 gene structure will be useful in the linkage analysis and search for mutations in the Fe65L2 gene in patients with Alzheimer's disease.

Alzheimer Disease↗
PubMed1987

Cytogenetic studies on human myeloma cell lines.

Cell lines (U-266, U-1957, U-1996 and U-2030) established from 4 patients with multiple myeloma (MM) were analyzed cytogenetically. The cell lines represent different stages in B-cell differentiation as evidenced by ultrastructural and functional characteristics. The karyotypic pattern in 3 newly established myeloma lines was studied after a few months in culture and compared to the old myeloma cell line U-266, which was examined after 6, 7 and 8 years of continuous cultivation. Frequency of progressive numerical and structural aberrations during long-term cultivation and their correlation with alterations in growth properties were addressed. We describe the presence of a high frequency of both numerical and structural chromosomal abnormalities in the cells of all 4 myeloma lines studied. Chromosomes often associated with structural abnormalities were 1, 3, 6, 12 and 14. A 14q + marker chromosome was detected in 2 of the 4 cell lines. The breakpoints on the chromosomes participating in structural aberrations in myeloma exhibit some correlation to chromosome sites at or close to locations of mapped oncogenes. No translocations of c-myc were found. These data were further supported by Southern blot analysis (unpublished data). The extent of numerical, but not structural, aberrations correlates with the differentiation stage of the myeloma lines in that the 2 mature lines U-266 and U-1957 were both near-diploid. Multiple progressive chromosomal changes have emerged in U-266 during a period of 8 years with development of independence of feeder cells and increased growth rate. However, capacity for production of complete Ig molecules has remained stable.

Aneuploidy↗
PubMed1999

Selective cleaning of the cell debris in human chromosome preparations studied by scanning force microscopy.

The chromosome structure is one of most challenging biological structures to be discovered. Most evidence about the structure comes from optical microscopy. Scanning force microscopy (SFM) can achieve molecular resolution and allows imaging in liquids. However, little information about the chromosome structure has been revealed by SFM. In this work, a mild enzymatic treatment is applied to the chromosomes to remove selectively the RNA and proteins coming from the cell. The resulting SFM images indicate that a protein film with embedded RNA molecules covers chromosomes in standard cytogenetic preparations. The thickness of the protein layer is 15-35 nm and the RNA adheres preferentially to the chromosome surface. The cell material film results in a quite smooth chromosome surface without evidence of any structural detail. After treatment, the chromosome was cleaned from cell residues and individual chromatin fibers at the surface were resolved. Furthermore, insights about the higher order structure of the chromosome can be inferred.

Chromatin↗
PubMed1997

The Drosophila gene fs(2)cup interacts with otu to define a cytoplasmic pathway required for the structure and function of germ-line chromosomes.

The Drosophila ovarian tumor gene (otu) encodes cytoplasmic proteins that are required in germ-line cells for cyst formation, nurse cell chromosome structure and egg maturation. We have analyzed a gene, fs(2)cup, that participates in many of the same processes and interacts with otu genetically. Both nurse cell and oocyte chromosomes require cup to attain a normal morphology. In addition, the gene is needed for the oocyte to grow normally by taking up materials transported from the nurse cells. The gene encodes a 1132-amino-acid protein containing a putative membrane-spanning domain. Cup protein (but not cup RNA) is transported selectively into the oocyte in germarial cysts, like the p104 Otu protein. It is strongly associated with large structures in the cytoplasm and perinuclear region of nurse cells and, like Otu, moves to the periphery of these cells in stages 9-10. Moreover, cup mutations dominantly disrupt meiotic chromosome segregation. We propose that cup, otu and another interacting gene, fs(2)B, take part in a common cytoplasmic pathway with multiple functions during oogenesis.

Amino Acid Sequence↗