The centromere is a chromosomal region that enables the accurate segregation of chromosomes during mitosis and meiosis. It holds sister chromatids together, and through its centromere DNA-protein complex known as the kinetochore binds spindle microtubules to bring about accurate chromosome movements. Despite this conserved function, centromeres exhibit dramatic difference in structure, size, and complexity. Extensive studies on centromeric DNA revealed its rapid evolution resulting often in significant difference even among closely related species. Such a plasticity of centromeric DNA could be explained by epigenetic c- trol of centromere function, which does not depend absolutely on primary DNA sequence. According to epigenetic centromere concept, which is thoroughly d- cussed by Tanya Panchenko and Ben Black in Chap. 1 of this book, centromere activation or inactivation might be caused by modifications of chromatin. Such acquired chromatin epigenetic modifications are then inherited from one cell di- sion to the next. Concerning centromere-specific chromatin modification, it is now evident that all centromeres contain a centromere specific histone H3 variant, CenH3, which replaces histone H3 in centromeric nucleosomes and provides a structural basis that epigenetically defines centromere and differentiates it from the surrounding chromatin. Recent insights into the CenH3 presented in this chapter add important mechanistic understanding of how centromere identity is initially established and subsequently maintained in every cell cycle.

Long non-coding RNAs (lncRNAs), tentatively defined as ncRNAs of more than two hundred nucleotides in length, are characterized by the complexity and diversity of their sequences and mechanisms of action. Based on genome-wide studies, more than 3,300 of them exist, but to date only the limited number of functional lncRNAs have been identified and characterized. Nonetheless, lncRNAs have emerged as key molecules involved in the control of transcriptional and posttranscriptional gene regulatory pathways. They take part in the recruitment of chromatin modifying complexes and regulate splicing, localization, stability and translation of the target mRNAs. This book provides an overview of the rapidly advancing field of long ncRNAs, describing the epigenetic and non-epigenetic mechanisms by which they regulate various biological functions in model systems, from yeast to mammals. The role of ncRNAs in sex chromosome dosage compensation in flies and mammals is described, as well as their role in centromere and telomere biology. Long non-coding RNAs involved in environmental stress response and development are presented and their mechanisms of action discussed.

Long non-coding RNAs (lncRNAs), tentatively defined as ncRNAs of more than two hundred nucleotides in length, are characterized by the complexity and diversity of their sequences and mechanisms of action. Based on genome-wide studies, more than 3,300 of them exist, but to date only the limited number of functional lncRNAs have been identified and characterized. Nonetheless, lncRNAs have emerged as key molecules involved in the control of transcriptional and posttranscriptional gene regulatory pathways. They take part in the recruitment of chromatin modifying complexes and regulate splicing, localization, stability and translation of the target mRNAs. This book provides an overview of the rapidly advancing field of long ncRNAs, describing the epigenetic and non-epigenetic mechanisms by which they regulate various biological functions in model systems, from yeast to mammals. The role of ncRNAs in sex chromosome dosage compensation in flies and mammals is described, as well as their role in centromere and telomere biology. Long non-coding RNAs involved in environmental stress response and development are presented and their mechanisms of action discussed.

The centromere is a chromosomal region that enables the accurate segregation of chromosomes during mitosis and meiosis. It holds sister chromatids together, and through its centromere DNA-protein complex known as the kinetochore binds spindle microtubules to bring about accurate chromosome movements. Despite this conserved function, centromeres exhibit dramatic difference in structure, size, and complexity. Extensive studies on centromeric DNA revealed its rapid evolution resulting often in significant difference even among closely related species. Such a plasticity of centromeric DNA could be explained by epigenetic c- trol of centromere function, which does not depend absolutely on primary DNA sequence. According to epigenetic centromere concept, which is thoroughly d- cussed by Tanya Panchenko and Ben Black in Chap. 1 of this book, centromere activation or inactivation might be caused by modifications of chromatin. Such acquired chromatin epigenetic modifications are then inherited from one cell di- sion to the next. Concerning centromere-specific chromatin modification, it is now evident that all centromeres contain a centromere specific histone H3 variant, CenH3, which replaces histone H3 in centromeric nucleosomes and provides a structural basis that epigenetically defines centromere and differentiates it from the surrounding chromatin. Recent insights into the CenH3 presented in this chapter add important mechanistic understanding of how centromere identity is initially established and subsequently maintained in every cell cycle.

This book gives a comprehensive overview of the unique roles that non-coding repetitive elements such as satellite DNAs play in different physiological and evolutionary processes. It presents the gene-regulatory aspect of satellite DNAs in different model systems including mammals, insects and plants. In addition, evolutionary aspects of activation of satellite DNAs in terms of transcription and proliferation are highlighted, revealing the role of satellite DNAs in the process of adaptation to changing environment and in the speciation process. Finally, the book discusses satellite DNA activation during pathological transformation and the mechanisms by which they affect disease progression. Namely, some satellite DNAs promote the oncogenic processes by affecting genome epigenetic regulation as well as genome integrity. Readers get a full overview of the latest research on satellite DNA.