The centromere directs the segregation of chromosomes during mitosis and meiosis. It is a distinct genetic locus whose identity is established through epigenetic mechanisms that depend on the deposition of centromere-specific centromere protein A (CENP-A) nucleosomes. This important chromatin domain has so far escaped comprehensive molecular analysis due to its typical association with highly repetitive satellite DNA. In previous work, we discovered that the centromere of horse chromosome 11 is completely devoid of satellite DNA; this peculiar feature makes it a unique model to dissect the molecular architecture of mammalian centromeres. Here, we exploited this native satellite-free centromere to determine the precise localization of its functional domains in five individuals: We hybridized DNA purified from chromatin immunoprecipitated with an anti CENP-A antibody to a high resolution array (ChIP-on-chip) of the region containing the primary constriction of horse chromosome 11. Strikingly, each individual exhibited a different arrangement of CENP-A binding domains. We then analysed the organization of each domain using a single nucleotide polymorphism (SNP)-based approach and single molecule analysis on chromatin fibres. Examination of the ten instances of chromosome 11 in the five individuals revealed seven distinct 'positional alleles', each one extending for about 80-160 kb, were found across a region of about 500 kb. Our results demonstrate that CENP-A binding domains are autonomous relative to the underlying DNA sequence and are characterized by positional instability causing the sliding of centromere position. We propose that this dynamic behaviour may be common in mammalian centromeres and may determine the establishment of epigenetic alleles.
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http://dx.doi.org/10.1007/s00412-014-0493-6 | DOI Listing |
Non-canonical (non-B) DNA structures-e.g., bent DNA, hairpins, G-quadruplexes, Z-DNA, etc.
View Article and Find Full Text PDFBrief Bioinform
November 2024
Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
Satellite DNAs (satDNAs) are tandemly repeated sequences that make up a significant portion of almost all eukaryotic genomes. Although satDNAs have been shown to play an important role in genome organization and evolution, they are relatively poorly analyzed, even in model organisms. One of the main reasons for the current lack of in-depth studies on satDNAs is their underrepresentation in genome assemblies.
View Article and Find Full Text PDFCell Mol Biol (Noisy-le-grand)
November 2024
Department of Plant Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, Al-Khoud 123, Muscat, Oman.
Tomato yellow leaf curl virus-Oman (TYLCV-OM), a variant of the Tomato yellow leaf curl virus-Iran (TYLCV-IR) strain, was identified in 2005 as the cause of tomato yellow leaf curl disease (TYLCD) in Oman and is associated with a betasatellite namely as Tomato leaf curl betasatellite (ToLCB). Surveys were carried out from three diverse Governorates of Oman to investigate the correlation between the betasatellite and the virus. The visual assessment and scoring of infected tomato plants in the field revealed that the association of betasatellite with the disease was highest in Sharqia at 77%, followed by Dakhlia at41% and lowest in Batinah at30% .
View Article and Find Full Text PDFBiochem Soc Trans
December 2024
Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, U.S.A.
Skeletal muscle cells (myofibers) require multiple nuclei to support a cytoplasmic volume that is larger than other mononuclear cell types. It is dogmatic that mammalian resident myonuclei rely on stem cells (specifically satellite cells) for adding new DNA to muscle fibers to facilitate cytoplasmic expansion that occurs during muscle growth. In this review, we discuss the relationship between cell size and supporting genetic material.
View Article and Find Full Text PDFAnn Bot
December 2024
Laboratory of Plant Cytogenetics and Evolution, Department of Botany, Federal University of Pernambuco, Recife-PE, Brazil.
Background And Aims: Genomic changes triggered by polyploidy, chromosomal rearrangements, and/ or environmental stress are among factors that affect the activity of mobile elements, particularly Long Terminal Repeats Retrotransposons (LTR-RTs) and DNA transposons. Because these elements can proliferate and move throughout host genomes, altering the genetic, epigenetic and nucleotypic landscape, they have been recognized as a relevant evolutionary force. Beaksedges (Rhynchospora) stand out for their wide cosmopolitan distribution, high diversity (~400 spp.
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