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An abundant tandem repeat has been cloned from genomic DNA of the merlin (Falco columbarius). The cloned sequence is 174 bp in length, and maps by in situ hybridization to the centromeric regions of several of the large chromosomes within the merlin karyotype. Complementary sequences have been identified within a variety of falcon species; these sequences(More)
Chromosomes from successive passages of a Chinese hamster cell strain (WCHE/5) that spontaneously progressed from a euploid primary cell culture to a heteroploid tumorigenic cell line were isolated and analyzed by Giemsa banding and high-resolution flow karyotype analysis. The frequency and identification of aneuploid and marker chromosomes were determined(More)
The immortalization of human diploid fibroblasts requires the circumvention of both the senescence (M1) and crisis (M2) mechanisms of growth control. Cells expressing the SV40 T antigen virtually always bypass senescence, but only rarely escape crisis. The low frequency of this latter event indicates that cellular mutations are necessary to escape crisis.(More)
The binding of 125I-diferric transferrin to cultured skin fibroblasts and phytohemagglutinin-stimulated lymphocytes was studied in cells derived from individuals homozygous for hereditary hemochromatosis and from normal individuals. Receptors with a high affinity for diferric transferrin were present on all cells. Transferrin receptor number decreased by(More)
The subcellular location of radiolabeled transferrin (125I-Tf), internalized during cellular iron uptake, and the cellular distribution of transferrin (Tf) receptors were studied in cultured HeLa cells. Cells were incubated at 37 degrees C with 125I-Tf(Fe)2. Forty per cent of the labeled ligand was associated with cell surface receptors. The remaining 60%(More)
Chinese hamster cell strains, each initiated from a separate fetus, were carried in culture and tested for tumorigenicity and in vitro indicators of neoplasia at various passage levels. In the absence of any treatment, all 20 such lineages yielded permanent cell lines and showed other indications of neoplastic progression. A preimplanted gelatin sponge(More)
Spontaneous neoplastic progression in cultured Chinese hamster cells was studied at the earliest stage possible. Eighteen independent newly immortalized cell populations (from six individual Chinese hamsters) were characterized for karyotype instability. Colonies were selected from initial sparse platings of adult or fetal cells and were expanded for study.(More)
A chromosome polymorphism was detected between two early passage euploid Chinese hamster cell strains when a fluorescence shift of the small metacentric No. 9 chromosome was resolved by flow cytometry. The characteristics of the polymorphism were studied using cultures established from ear clippings taken from 16 additional hamsters from our breeding(More)
To define the role of SV40 large T antigen in the transformation and immortalization of human cells, we have constructed a plasmid lacking most of the unique coding sequences of small t antigen as well as the SV40 origin of replication. The promoter for T antigen, which lies within the origin of replication, was deleted and replaced by the Rous sarcoma(More)