Chromosome

About: Chromosome is a research topic. Over the lifetime, 17538 publications have been published within this topic receiving 660077 citations. The topic is also known as: chromosomes & GO:0005694.

Autoantibody to centromere (kinetochore) in scleroderma sera.

Abstract: Sera from patients with scleroderma contained several autoantibodies to nuclear antigens which were distinguished by different patterns of nuclear immunofluorescence staining. One of these autoantibodies reacted with centromeric regions of chromosomes. In chromosome spreads, the staining appeared as two small spheres at the centromere, resembling kinetochores. The antigenic determinant appeared to be a protein or polypeptide tightly bound to DNA. The autoantibody was reactive with centromeres of cells derived from humans, mice, and Chinese hamsters. The autoantibody was present in high frequency in the calcinosis/Raynaud's phenomenon/esophageal dysmotility/sclerodactyly/telangiectasia variant (CREST) of scleroderma.

An electrophoretic karyotype for yeast

Abstract: The chromosomal DNA molecules of a standard laboratory strain of Saccharomyces cerevisiae have been separated into 12 well-resolved bands by orthogonal-field-alternation gel electrophoresis. DNA X DNA hybridization probes derived from cloned genes have been used to correlate this banding pattern with yeast's genetically defined chromosomes. The 12 bands are shown to represent 9 singlets and 3 comigrating doublets, thereby accounting for 15 chromosomes that were identified as I-XI and XIII-XVI. Because the three comigrating doublets could be readily resolved in certain laboratory yeast strains that contain chromosome-length polymorphisms relative to our standard strain, all 15 of these chromosomes could be displayed as a single band in at least one of four strains that were studied. A 16th chromosome (number XII), which is known to contain the genes for rRNA, does not reproducibly enter the gels. By making use of the band identifications, the previously unmapped fragment F8 was assigned to chromosome XIII. With the possible exception of chromosomes that differ greatly in size or electrophoretic behavior from all the known chromosomes, the results appear to define a complete "electrophoretic karyotype" for yeast.

Sequence elimination and cytosine methylation are rapid and reproducible responses of the genome to wide hybridization and allopolyploidy in wheat

Abstract: Interspecific or intergeneric hybridization, followed by chromosome doubling, can lead to the formation of new allopolyploid species. Recent studies indicate that allopolyploid formation is associated with genetic and epigenetic changes, although little is known about the type of changes that occur, how rapidly they occur, and the type of sequences involved. To address these matters, we have surveyed F1 hybrids between diploid species from the wheat (Aegilops and Triticum) group and their derived allotetraploids by screening a large number of loci using amplified fragment length polymorphism and DNA gel blot analysis and by assaying the extent of cytosine methylation. We found that sequence elimination is one of the major and immediate responses of the wheat genome to wide hybridization or allopolyploidy, that it affects a large fraction of the genome, and that it is reproducible. In one cross between Ae. sharonensis × Ae. umbellulata, 14% of the loci from Ae. sharonensis were eliminated compared with only 0.5% from Ae. umbellulata, with most changes occurring in the F1 hybrid. In contrast, crosses between Ae. longissima × T. urartu showed that sequence elimination was more frequent after chromosome doubling. Alterations in cytosine methylation occurred in ∼13% of the loci, either in the F1 hybrid or in the allopolyploid. For eight of nine bands that were isolated, the sequences that underwent elimination corresponded to low-copy DNA, whereas alterations in methylation patterns affected both repetitive DNA sequences, such as retrotransposons, and low-copy DNA in approximately equal proportions.

The human CENP-A centromeric nucleosome-associated complex

Abstract: The basic element for chromosome inheritance, the centromere, is epigenetically determined in mammals. The prime candidate for specifying centromere identity is the array of nucleosomes assembled with CENP-A, the centromere-specific histone H3 variant. Here, we show that CENP-A nucleosomes directly recruit a proximal CENP-A nucleosome associated complex (NAC) comprised of three new human centromere proteins (CENP-M, CENP-N and CENP-T), along with CENP-U(50), CENP-C and CENP-H. Assembly of the CENP-A NAC at centromeres is dependent on CENP-M, CENP-N and CENP-T. Facilitates chromatin transcription (FACT) and nucleophosmin-1 (previously implicated in transcriptional chromatin remodelling and as a multifunctional nuclear chaperone, respectively) are absent from histone H3-containing nucleosomes, but are stably recruited to CENP-A nucleosomes independent of CENP-A NAC. Seven new CENP-A-nucleosome distal (CAD) centromere components (CENP-K, CENP-L, CENP-O, CENP-P, CENP-Q, CENP-R and CENP-S) are identified as assembling on the CENP-A NAC. The CENP-A NAC is essential, as disruption of the complex causes errors of chromosome alignment and segregation that preclude cell survival despite continued centromere-derived mitotic checkpoint signalling.

Zebrafish Comparative Genomics and the Origins of Vertebrate Chromosomes

Abstract: To help understand mechanisms of vertebrate genome evolution, we have compared zebrafish and tetrapod gene maps. It has been suggested that translocations are fixed more frequently than inversions in mammals. Gene maps showed that blocks of conserved syntenies between zebrafish and humans were large, but gene orders were frequently inverted and transposed. This shows that intrachromosomal rearrangements have been fixed more frequently than translocations. Duplicated chromosome segments suggest that a genome duplication occurred in ray-fin phylogeny, and comparative studies suggest that this event happened deep in the ancestry of teleost fish. Consideration of duplicate chromosome segments shows that at least 20% of duplicated gene pairs may be retained from this event. Despite genome duplication, zebrafish and humans have about the same number of chromosomes, and zebrafish chromosomes are mosaically orthologous to several human chromosomes. Is this because of an excess of chromosome fissions in the human lineage or an excess of chromosome fusions in the zebrafish lineage? Comparative analysis suggests that an excess of chromosome fissions in the tetrapod lineage may account for chromosome numbers and provides histories for several human chromosomes.