Karyotype

About: Karyotype is a research topic. Over the lifetime, 16278 publications have been published within this topic receiving 416409 citations.

Visualization of nucleolar organizer regions im mammalian chromosomes using silver staining

Abstract: A simple ammoniacal silver staining procedure, designated Ag-AS, differentially stains the chromosomal locations of ribosomal DNA in certain mammalian species. This was critically demonstrated by Ag-AS staining of the nucleolus organizer regions in karyotypes of the same species and cell lines used for locating the ribosomal cistrons by DNA/RNA in situ hybridization. With Ag-AS, silver stained NORs (Ag-NORs) are visualized as black spherical bodies on yellow-brown chromosome arms. Ag-NORs were visualized throughout mitosis at the secondary constrictions in the rat kangaroo, Seba's fruit bat, Indian muntjac, and Rhesus monkey. The Chinese hamster and cattle have telomeric Ag-NORs, the mouse subcentromeric Ag-NORs, and the field vole Ag-NORs as minute short arms or choromosomal satellites. Ag-NORs occur at both secondary constrictions and at telomeres in the cotton rat. Variability in Ag-NOR pattern included differences in the number of Ag-NORs per cell within a cell population, size of Ag-NORs among chromosomes of a complement, and presence of Ag-NOR on particular chromosomes in two cell lines of the Chinese hamster. The available cytochemical data suggest that the Ag-AS reaction stains chromosomal proteins at the NOR rather than the rDNA itself.

Recurrent gain of chromosomes 17q and 12 in cultured human embryonic stem cells

Abstract: We have observed karyotypic changes involving the gain of chromosome 17q in three independent human embryonic stem (hES) cell lines on five independent occasions. A gain of chromosome 12 was seen occasionally. This implies that increased dosage of chromosome 17q and 12 gene(s) provides a selective advantage for the propagation of undifferentiated hES cells. These observations are instructive for the future application of hES cells in transplantation therapies in which the use of aneuploid cells could be detrimental.

Characteristic chromosomal abnormalities in biopsies and lymphoid‐cell lines from patients with burkitt and non‐burkitt lymphomas

Abstract: The karyotypes of cells from 10 Burkitt lymphoma (BL) biopsies, eight cell lines established from BL and nine cell lines from non-BL sources were studied by chromosome banding techniques. With the exception of the BL-derived cell lines BJAB, GC-BJAB, Maku and U-8691 all biopsies and lines of Burkitt origin contained an extra band at the distal region of the long arm of one chromosome 14. An extra band on chromosome 14 was also found in cells of one non-BL biopsy, in cells from a lymphosarcoma-derived cell line and in a long-established cell line derived from the pleural exudate of a patient with Hodgkin's disease. A distal region at the long arm of one chromosome 8 was missing in all metaphase figures of good technical quality in the same material. The size, morphology and stain-ability of the missing region corresponded fairly well to the extra region at chromosome 14. We therefore suggest that the chromosome 14 marker represents a translocation between chromosomes 8 and 14,t (8q-; 14q+). The translocation was present neither in lymphocytes of the peripheral blood of five Burkitt patients nor in five lymphoblastoid cell lines of non-BL origin. Trisomy 7 was found in two of the 10 BL biopsies, in two BL-derived cell lines, in one non-BL biopsy, in two lymphosarcoma-derived cell lines and in one cell line derived from a patient with Hodgkin's disease.

Localization of single copy DNA sequences of G-banded human chromosomes by in situ hybridization.

Abstract: Recombinant lambda bacteriophage clone H3 containing a human DNA segment of 14.9 kb present in one or two copies per haploid genome was isolated. In situ hybridization in human metaphase chromosomes of the 3H-labeled cloned DNA resulted in highly significant labeling (53% of cells) of band p36 of chromosome 1, such that 22% of all chromosomal grains were located on this region. Hybridization was dependent upon the presence of dextran sulfate in the hybridization mixture and was not affected by repetitive DNA competitor. These results demonstrate localization of a single copy sequence on human metaphase chromosomes.

Homogeneously staining chromosomal regions contain amplified copies of an abundantly expressed cellular oncogene (c-myc) in malignant neuroendocrine cells from a human colon carcinoma.

Abstract: Two human neuroendocrine tumor cell lines derived from a colon carcinoma contain either numerous double minute chromosomes (COLO 320 DM) or a homogeneously staining marker chromosome (COLO 320 HSR). We found amplification and enhanced expression of the cellular oncogene c-myc in both COLO 320 DM and HSR cells, and we were able to show that the homogeneously staining regions of the COLO 320 HSR marker chromosome contain amplified c-myc. From previous and present karyotypes, it appears that the homogeneously staining regions reside on a distorted X chromosome. Therefore, amplification of c-myc has been accompanied by translocation of the gene from its normal position on chromosome 8 (8q24). Because double minute chromosomes were features of primary cultures from the original tumor, it seems reasonable to suspect that amplification of c-myc may have contributed to tumorigenesis.