These findings also underscore the unique nature of silencing in pericentromeric regions, which encompasses large swaths of silent chromatin and encompasses many repeat elements.
This might be because centromeres have many repeat elements.
For example, we identified many novel repeated elements (RE) in 3'UTRs, suggesting an invasion of most animal sequences by some specific RE families.
We identified many new repeated elements in the 3'UTR of most animal genes, suggesting that these elements potentially have a biological role, especially with respect to gene expression regulation.
The plant mitochondrial genome content is highly dynamic: plant mitochondrial DNA (mtDNA) is the largest and least gene-dense among the eukaryotes and variable in size (200 to 2,500 kb), and contains many introns and repeated elements (typically 90% of the total sequence), [ 15, 16].
Its content is highly dynamic: plant mitochondrial DNA (mtDNA) is large and variable in size (200 to 2,500 kb), contains many introns and repeated elements (typically 90% of the total sequence), and experiences frequent gene gain/loss/transfer/duplication, and genome rearrangements [ 1].
Other examples include genomic islands of Prochlorococcus cyanobacteria, which encompass genes for various metabolite transporters (potential targets of virus recognition) as well as many tRNA genes, repeat elements and integrases, which can enhance the rate of recombination in these islands [ 38].
This can be explained at least in part by the fact that there are not so many repeated sequences, such as Ty elements (1.8%), in the total yeast chromosome as in the mammalian genome (Krebs et al. 2009).
We found that approximately half of the transcription units discovered in our GRO-seq data can be mapped to annotated regions, including genes encoding proteins, long non-coding RNAs (lncRNAs), microRNAs (miRNAs), tRNAs, snRNAs, and repeat elements, many of which are relevant to cardiac biology (e.g., the mRNA CFLAR, the lncRNA MALAT1, the microRNA 21 precursor MIR21; Additional file 1).
Because intergenic spacers of many repeated eukaryotic genes contain MAR/SARs and insulators, our observations suggest that these elements have the ability to segregate repeated genes into domains that act independently of one another.
