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Results for “Chromosome Structures”

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At least 145 records · Page 8Linked to original sources
PubMed1988

A new application of in situ hybridization: detection of numerical and structural chromosome aberrations with a combination centromeric-telomeric DNA probe.

Fluorescent in situ hybridization provides a fast method for detection of specific nucleic acid sequences. We have used high-resolution, single-color fluorescent in situ hybridization with a combination centromeric-telomeric DNA probe, specific for chromosome 1, to investigate the feasibility of simultaneous assessment of numerical and structural chromosome aberrations. The K562 leukemia cell line served as a model.

Centromere↗
PubMed1977

[Effect of carbon disulfide on peripheral blood leukocytes. I. Effect of carbon disulfide on in vitro chromosome structure and division capability of leukocytes in man].

The peripheral blood leukocytes in normal subjects were cultured according to Moorhead with addition of CS2 (0,75 microliter/ml of culture). It has been found that CS2 decreases the mitotic index, and in some cultures inhibits totally the cell division. Moreover, it causes structural disturbances of chromosomes being of pre- and postreplicative character as well as their viscous degeneration, lesser spiralization and sometimes pulverization. The presence of greater amount of erythrocytes of the donor's blood in the culture markedly diminished the intensity of these changes.

Adolescent↗
PubMed1990

The tannin-osmium conductive staining after dehydration: an attempt to observe the chromosome structure by SEM without metal coating.

The tannin-osmium conductive staining method was modified in order to observe chromosomal structures without metal coating. The treatment with tannic acid and OsO4, which has been used in aqueous solution in the original method, was performed in acetone solution after dehydration in the present study. The usefulness of this method is discussed showing ultrastructural images of chromosomes of Drosophila and Tradescantia, which can be achieved by the method.

Animals↗
PubMedDate not supplied

Experiences with unexpected structural chromosome aberrations in prenatal diagnosis in a Danish series.

The investigation of 5547 prenatal diagnoses showed 31 unexpected structural chromosome rearrangements. These included 3 Robertsonian translocations, 14 reciprocal translocations and 14 inversions. All were balanced, including 5 de novo rearrangements. In 3 of these cases an induced abortion was performed and in 2 cases children without detectable malformations were delivered.

Adult↗
PubMed2006

[Human Y chromosome: structure and biological role].

Y chromosome differs from other human chromosomes. It is found in cells of the male persons only. Different human phenotypes are associated with non-recombinant region of Y chromosome. This chromosome is of great significance in the human sex determination and the development of male gametes (spermatogenesis). Testes develop in embryos which have the Y chromosome, and ovaries develop in embryos which have no Y chromosome. SRY (sex-determining region of the Y chromosome) gene determines the male phenotype. Translocation of this gene determines sex reversal. The aim of this article was to review the structure and biological functions of the human Y chromosome.

Chromosomes, Human, Y↗
PubMed2000

Human chromosome structure studied by scanning force microscopy after an enzymatic digestion of the covering cell material.

In standard preparations, metaphase human chromosomes are covered by a cell material film composed mainly of proteins and RNA. This film (approximately 30 nm thickness) hides the chromosome structure to the tip of a scanning force microscope. In this work, a mild enzymatic treatment is applied to remove the cell material film. After treatment, the individual chromatin fibers at the surface were resolved. Furthermore, the chromosome shows a thickness modulation, in which thicker/thinner regions could be associated with G/R bands. Finally, the topography of the chromosomes in solution is presented. The chromosome volume swelled about five-fold and chromatin packaging in bands and coils was observed.

Air↗
PubMed1999

The human BARX2 gene: genomic structure, chromosomal localization, and single nucleotide polymorphisms.

The BARX genes 1 and 2 are Bar class homeobox genes expressed in craniofacial structures during development. In this report, we present the genomic structure, chromosomal localization, and polymorphic markers in BARX2. The gene has four exons, ranging in size from 85 to 1099 bp. BARX2 is localized on human chromosome 11q25, as determined by radiation hybrid mapping. In the mouse, Barx2 is coexpressed with Pitx2 in several tissues. Based on the coexpression, BARX2 was assumed to be a candidate gene for those cases of Rieger syndrome that cannot be associated with mutations of PITX2. Mutations in PITX2 cause some cases of Rieger syndrome, an autosomal dominant disorder affecting eyes, teeth, and umbilicus. DNA from Rieger patients was subjected to single-strand conformation polymorphism screening of the BARX2 coding region. Three single nucleotide polymorphisms were found in a normal population, although no etiologic mutations were detectable in over 100 cases of Rieger syndrome or in individuals with related ocular disorders.

Alleles↗
PubMed1982

Role of non-histones in chromosome structure. Cell cycle variations in protein synthesis.

As part of a study of the role of non-histone proteins in chromosome structure, the synthesis of non-histones associated with interphase chromatin was investigated. Synchronized suspension cultures of HeLa cells were pulse-labeled with [35S]methionine, and chromatin was prepared by mild micrococcal nuclease digestion. Two-dimensional polyacrylamide gel electrophoresis, in addition to one-dimensional electrophoresis, was used to resolve the patterns of incorporation of radioactive label. Significant variations in non-histone synthesis were seen during the cell cycle. A strong correlation was not found between DNA synthesis in mid-S phase and variations in non-histone synthesis. The non-histone proteins of purified metaphase chromosomes were also characterized by two-dimensional gel electrophoresis and compared to the proteins of interphase chromatin. The pattern of non-histones is not identical with that of interphase chromatin, although a number of major species may be shared by interphase chromatin and metaphase chromosomes. The HeLa nuclear scaffold, the framework that maintains the overall morphology of the interphase nucleus, shows relatively few proteins on two-dimensional gels. The synthesis of nuclear scaffold proteins was quantitated by excising each of 19 proteins from two-dimensional gels and determining the incorporated radioactivity by scintillation counting. Substantial variations in protein synthesis were found, with several species showing changes of about 2-fold in the percentage of incorporation.

Cell Cycle↗
PubMed1995

Cytogenetics of human spermatozoa: what about the reproductive relevance of structural chromosome aberrations?

PURPOSE: The purpose was to review and appreciate data on structural sperm chromosome abnormalities obtained after fusion of human spermatozoa with zona-free hamster eggs. RESULTS: Breaks and fragments are the predominant sperm chromosome aberrations. In contrast to stable alterations, e.g., translocations, inversions, and deletions that will be transmitted unchanged into following cell generations, breaks, fragments, and some rearrangements have a reduced stability. In proliferating cell systems they will soon be eliminated through formation of lagging chromatin and micronuclei. Their relevance lies in a loss of genetic material or disturbance of cell division that may cause cell death. It is reasonable to assume a responsibility of such aberrations for early unrecognized conception loss. However, this interpretation is subject to criticism because an artifactual origin of sperm chromosome breakage cannot be ruled out. CONCLUSIONS: The incidence and relevance of structural sperm chromosome abnormalities will remain at issue unless additional and complementary information is provided. For this purpose, new strategies must be developed because further studies employing hamster eggs according to existing protocols will not help resolve the dilemma.

Animals↗
PubMed1982

Unexpected structural chromosome rearrangements in prenatal diagnosis.

Among 5315 prenatal diagnoses performed for various indications (maternal age, neural tube defect, metabolic diseases, X-linked diseases, pathologic pregnancies) 29 unexpected structural chromosome rearrangements were found in fetal cells. Fourteen were de novo chromosome rearrangements, six unbalanced, and eight balanced. Fifteen were inherited and balanced rearrangements. This high frequency of structural anomalies is discussed.

Adult↗
PubMed1975

Derivative chromosomal structures from a ring chromsome 4.

This report describes the results from cultured lymphocytes studied at metaphase, anaphase, and interphase from an individual with a ring chromosome 4. A ring was present in 90.1% of metaphases. Special attention was directed towards the occurrence of derivative chromosomal structures, such as partially duplicated and triplicated rings, tricentric rings, chains of 3 interlocked rings, rod-shaped chromosomes, "pulverized" rings, and others. The clinical features of the individual (small stature and impaired mental development, hypoplastic thumbs, ptosis palpebrae hypoplastic external male genitalia, abnormal dermatoglphic pattern) did not conform to a specific phenotype.

Blood Group Antigens↗
PubMed2002

Suppression of heterochromatic gene variegation can be used to distinguish and characterize E(var) genes potentially important for chromosome structure in Drosophila melanogaster.

Hundreds of genic modifiers of position effect variegation (PEV) have been isolated in Drosophila melanogaster with a view to identifying genes important for chromosome structure. Here we propose a supplementary genetic screen to pinpoint candidate genes that are most likely to function in chromosome organization, within the enhancer of variegation [E(var)] class of modifiers. Our strategy takes advantage of the fact that variegating euchromatic and heterochromatic genes respond oppositely to changes in the dosage of heterochromatin proteins. Consequently, only when enhancement of euchromatic gene variegation results from increased formation of heterochromatin should suppression of heterochromatic gene variegation be observed. Mutations in four E(var) genes were tested for the ability to suppress variegation of multiple alleles of the heterochromatic light ( lt) gene in a variety of tissues and at several developmental stages. Mutations in E(var)3-4, E(var)3-5 and modifier of mdg4 [ mod(mdg4)] suppressed lt variegation. In contrast, a mutation in the Trithorax-like ( Trl) gene, which encodes GAGA factor, enhanced or had no effect on lt variegation, consistent with its known role in promoting transcription. These data show that suppression of lt variegation can be used as an assay to distinguish between members of the E(var) class of modifiers.

Animals↗
PubMed1994

Induction of structural chromosome aberrations in human lymphocyte cultures and CHO cells by permethrin.

The pyrethroid insecticide permethrin was tested for its ability to induce structural chromosome aberrations (CA) in human lymphocyte cultures and CHO cells, in order to confirm the clastogenic effect of itself and to compare the response of the two different cell types. Permethrin was tested in the range of 50-200 micrograms/ml in human lymphocyte cultures and in the range of 20-100 micrograms/ml in CHO cells. In both lymphocyte and CHO cultures, assays were performed in the absence and in the presence of a rat liver activation system (S9 mix). In the absence of S9 mix, two experiments with different duration of the treatment were carried out. Permethrin induced CA in both cultures when it was evaluated in the absence of a metabolic activation system. The activity of a given concentration of permethrin seemed to be decreased more by the reduction of the time of exposure than by the presence of S9 mix. Aberrations induced by permethrin were mainly chromosome-type aberrations in both cultures. Thus, permethrin can be characterised as an S-phase independent clastogenic agent. The response of both lymphocyte and CHO cultures was similar, indicating that both systems showed the same sensitivity for detecting the clastogenicity in vitro of permethrin.

Animals↗