We report a neocentromere event on maize chromosome 3 that occurred due to chromosome breakage. The neocentromere lies on a fragment of the short arm that lacks the primary centromere DNA elements, CentC and CRM. It is transmitted in the genomic background of oat via a new centromere (and kinetochore), as shown by immunolocalization of the oat CENH3 protein. Despite normal transmission of the m...

Proper deposition and activation of Aurora B at the centromere is critical for faithful chromosome segregation in mammals. However, the mechanistic basis for abrupt Aurora B kinase activation at the centromere has not yet been fully understood. We demonstrate here that Aurora B-mediated phosphorylation of histone H2AX at serine 121 (H2AX-pS121) promotes Aurora B autophosphorylation and is essen...

Supernumerary chromosomes are widespread in the plant kingdom but little is known of their molecular nature or mechanism of origin. We report here the initial cloning of sequences from the maize B chromosome. Our analysis suggests that many sequences are highly repetitive and shared with the normal A chromosomes. However, all clones selected for B-specificity contain at least one copy of a part...

A centromere is a special region in the chromosome that plays a vital role during cell division. Every new chromosome created by a genome rearrangement event must have a centromere in order to survive. This constraint has been ignored in the computational modeling and analysis of genome rearrangements to date. Unlike genes, the different centromeres are indistinguishable, they have no orientati...

L ike a parachute jump, mitosis can go badly wrong unless every connection is sound. The repetitive DNA sequences located at centromeres help secure mitotic links, Bassett et al. show (1). Contradicting previous evidence that the sequences are expendable, the study indicates that they help attract proteins necessary to repair faulty chromosome connections. Centromeres ensure that mitotic spindl...

In meiosis I, exchanges provide a connection between homologous chromosome pairs that facilitates their proper attachment to the meiotic spindle. In many eukaryotes, homologous chromosomes that fail to become linked by exchanges exhibit elevated levels of meiotic errors, but they do not segregate randomly, demonstrating that mechanisms beyond exchange can promote proper meiosis I segregation. T...

A panel of 15 human BAC/PAC probes, covering the entire chromosome 6, was used in FISH experiments on great apes and on representatives of Old World monkeys, New World monkeys, and lemurs to delineate the chromosome 6 phylogeny in primates. The domestic cat was used as an outgroup. The analysis showed a high marker order conservation, with few rearrangements required to reconcile the hypothesiz...

In the fission yeast Schizosaccharomyces pombe genes are transcriptionally silenced when placed within centromeres, within or close to the silent mating-type loci or adjacent to telomeres. Factors required to maintain mating-type silencing also affect centromeric silencing and chromosome segregation. We isolated mutations that alleviate repression of marker genes in the inverted repeats flankin...

The organization of chromosomes into territories plays an important role in a wide range of cellular processes, including gene expression, transcription, and DNA repair. Current understanding has largely excluded the spatiotemporal dynamic fluctuations of the chromatin polymer. We combine in vivo chromatin motion analysis with mathematical modeling to elucidate the physical properties that unde...

In the midst of an increasingly detailed understanding of the molecular basis of genome regulation, we still only vaguely understand the relationship between molecular biochemistry and the structure of the chromatin inside of cells. The centromere is a structurally and functionally unique region of each chromosome and provides an example in which the molecular understanding far exceeds the unde...