‘‘C-value paradox’’ or ‘‘C-value enigma’’, has intrigued
biologists for over half a century. Rapid advances in DNA sequencing are now
providing compelling evidence showing that variation in DNA amount arises
predominantly from differences in the frequency of polyploidy, abundance of
non-coding repetitive DNA and the dynamics of the processes that amplify, erode
and delete DNA. Repetitive elements (REs) comprise large proportions of
eukaryotic genomes and are fundamental to the evolutionary process. REs can be
classified as interspersed or tandem repeats. Interspersed repeats include
transposable elements (e.g., retrotransposons), which encode proteins that
facilitate their movement and proliferation in genomes. Tandem repeats (e.g.,
satellite DNAs) can form large blocks (e.g., megabases) of relatively short
non-coding sequences in repeated arrays. Together, interspersed and tandem
repeats comprise a major fraction of the prokaryotic and eukaryotic genomes.
REs exhibit an array of structural and evolutionary effects
on genome evolution across species. TEs can be associated with genome
rearrangement through various mechanisms, such as de novo TE insertion, TE
insertion-mediated deletion, and homologous recombination between them. These
rearrangements increase the genomic difference between genomes, and some
specific rearrangements may lead to complex diseases. TEs transpose and insert
themselves between genes; they can disrupt gene order, create gene
duplications, or cause gene deletions. These structural changes can have
significant effects on the organisation and function of the genome. Also,
through recombination, TEs can serve as recombination sites in the genome,
promoting genomic rearrangements. Recent studies reveal that
chromosome-specific repetitive elements and small RNA-based chromatin
regulation have been repeatedly adapted to guide epigenetic regulation of a
chromosome. In the present book, we explore several aspects of Repetitive DNA
ranging from chromosome to transcriptional regulation. At the chromosomal level
roles of RE in Centromere organisation, histone and kinetochore dynamics
evolution, viability and degeneration are reviewed using representative
examples. Epigenetic and roles of repetitive DNA in human diseases have been
recognised as niche areas by researchers furthering the role of RE in gene
regulation, sex chromosome differentiation, are its major contribution to
genomes.
Author(s) Details
Kiran Kumar Halagur
Bhoge Gowda
Affiliated to Nrupathunga University, India.
Please see the book here:- https://doi.org/10.9734/bpi/mono/978-81-991027-6-7
