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Epigenetic modification of “euchromatic” satellite DNAs in the red flour beetle Tribolium castaneum.

Eukaryotic genomes contain a considerable fraction of satellite DNAs (long arrays of tandemly repeated sequences) highly prevalent in pericentromeric heterochromatin. Nevertheless, information about satellite DNA distribution and their corresponding chromatin organization outside of these regions is rather limited. The availability of a whole-genome assembly mapped to Tribolium castaneum chromosomes makes possible examination of satellite DNAs on the genome-wide scale. Recently, using a combination of bioinformatics and experimental approaches, we identified and studied content, distribution, and structural features of satellite DNAs throughout the entire genome. We detected that besides one highly abundant satellite DNA in pericentromeric regions, several different satellite DNAs are distributed exclusively in euchromatic chromosomal arms of all chromosomes (Pavlek et al. 2015). We hypothesize that satellite DNA islands in the euchromatic regions could be important factors in the modulation of gene expression through the formation of micro-heterochromatic environment. We therefore decided to test epigenetic status of selected satellite DNAs. First we used IF/FISH to recover correlation between distribution of heterochromatic or euchromatic H3 histone modifications (H3K9me3 and H3K4me3, respectivelly) and satellite DNAs. In addition, we explored DNA methylation status of these satellite DNAs by Southern blot analyses of genomic DNA digested with methylation sensitive restriction endonucleases.

satellite DNAs ; Tribolium castaneum ; H3 histone modification ; DNA methylation

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