1,721,009 research outputs found
Identification and chromosomal distribution of a human chromosome 9 duplicon mediating meiotic and somati crearrangements.
No full textOccurence and expansion of trisomy 7 in a fibroblast strain from a centenarian individual.
No full textWe describe the presence of metaphases with non-random gain of one or two chromosomes in a skin fibroblast strain derived from a centenarian individual. The extra elements were chromosomes 7, X, and 18, and, among these, the most frequent was a 7. During in vitro propagation +7 cells seemed to be stable and overrode the diploid ones. After prolonged growth in culture, the cell population displayed the typical senescence signs. Our findings confirm the proneness to aneuploidy in cells from aged individuals and indicate that, while the presence of a trisomic 7 may confer a selective advantage to cells grown in vitro, it does not seem to prevent cellular senescence
Insertion of a loxP site in a size-reduced human accessory chromosome
No full textThe generation in vitro of mammalian artificial chromosomes, in view of the possibility of developing new technologies for gene therapy, is still an ambitious goal. Mammalian artificial chromosomes, to be used as cloning and expression vectors, have been constructed either by de novo synthesis or by reduction of pre-existing chromosomes. In the work here reported, we introduced a loxP sequence into the pericentromeric region of a chromosome 9-derived X-ray-reduced minichromosome, with the purpose of generating a human chromosome vector (HCV). The modified accessory chromosome is linear and mitotically stable, has lost at least 1400 kb of alpha satellite DNA and normally binds CENP-B, CENP-C and CENP-E. The efficiency of gene targeting via loxP mediated homologous recombination was tested using the histone H2B-Green Fluorescent Protein chimaeric gene as a reporter. The frequency of site-specific insertion of the exogenous sequence was found to be about 50% and to occur in a controlled way with regard to the number of copies. The expression level of the fusion protein was stable over prolonged time in culture. . Copyright 2002 S. Karger AG, Base
Assignment of the human connexin 32 gene (GJB1) to band Xq13.
No full textThe chromosomal localization of the human gene coding for connexin 32 (GJB1) was determined by in situ suppression hybridization (ISSH). The results allowed assignment of the gene to band Xq13, thus refining previous localization data obtained by means of somatic cell hybrid analysis
Two extended arrays of a satellite DNA sequence at the centromere and at the short arm telomere of Chinese hamster chromosome 5.
No full textWe have cloned a Chinese hamster chromosome-specific repeated sequence (SatCH5). This satellite is composed of a 33-bp unit organized in two extended tandem arrays. It is localized at the centromere and at the short-arm subtelomere of chromosome 5. Altogether, SatCH5 covers about 1-2 Mb per diploid genome and is not present in other species, including the Syrian hamster and mouse. Since it is known in the Chinese hamster and numerous other vertebrate species that telomeric (TTAGGG)n repeats are localized at the centromeres of several chromosomes, we studied the localization of SatCH5 relative to (TTAGGG)n sequences. Using two-color fluorescence in situ hybridization on stretched chromosomes and on DNA fibers, we have shown that at the centromere of chromosome 5 SatCH5 and the (TTAGGG)n arrays are contiguous. SatCH5 is the first chromosome-specific repetitive sequence located at both the pericentromeric and subtelomeric regions of the same chromosome
Isolation from the horse genome of a new DNA transposon belonging to the Tigger family.
No full textTigger elements are human DNA transposons homologous to the pogo element of Drosophila melanogaster. They contain an open reading frame for a transposase very similar to the major mammalian centromere protein CENP-B. We found in the horse genome a DNA element ( Ecatig3) sharing 88% homology with human Tigger3. The presence of Tigger elements in the horse genome confirms previous data that date these elements before the divergence between Perissodactyla and Primates (80-90 Myr ago). Copy number evaluation indicates that the horse element is much more abundant than its human counterpart. Southern blot analysis demonstrates that Ecatig3 elements are extremely homogeneous; this may indicate that the evolution of this DNA transposon has been driven by some kind of selection and has not been neutral
The Generation of a Human Minichromosome Vector Containing a loxP Site.
No full textA human chromosome vector has been constructed by inserting a homologous recombination site in an artificially modified minichromosome
ASSIGNEMENT OF A HUMAN GENE ENCODING HETEROGENEOUS NUCLEAR RNA RIBONUCLEPROTEIN 1 (PTB) TO CHROMOSOME 14q23-q24.1
No full textCharacterization of hamster-bovine somatic cell hybrids by in situ hybridization and chromosome banding.
No full textHere we describe the molecular cytogenetic characterisation of bovine -hamster somatic cell hybrids. A protocol, based on interphase analysis of single cells, for the rapid selection of hybrid clones to be further analysed was developed
GENE TARGETING TO THE CENTROMERIC DNA OF A HUMAN MINICHROMOSOME
No full textA human supernumerary minichromosome (MC), previously identified as a derivative of chromosome 9, has been introduced into Chinese hamster ovary (CHO) cells by means of cell fusion. A hybrid clone containing the MC as the only free human chromosome was isolated. A selectable marker gene (neo) inserted into a yeast artificial chromosome (YAC) has been successfully targeted to the MC centromeric DNA via co-transfection with chromosome-9-specific alpha satellite DNA. In situ hybridization and Southern blotting experiments demonstrated that the intact neo gene was integrated into the MC centromeric DNA. Studies on the clonal distribution and on the stability of the MC either in the presence or in the absence of the selective agent have been carried out. The MC is susceptible to further manipulations and may thus represent a model for the construction of a large-capacity vector for somatic gene therapy
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