Publications - Working papers
Please find below working papers of our group. Currently, we list 58 working papers.
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Genome Size and DNA Methzlation Rate are positively correlated in Metazoans
Marcus Lechner, Manja Marz, Christian Ihling, Andrea Sinz, Peter F. Stadler, Veiko Krauss
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Abstract
The distribution and function of DNA methylation in metazoans so far has been
studied only in chordates, some insects, and Nematostella in any detail. While it
is known that DNA methylation rates vary widely between different species, the
phylogenetic distribution of this variation has not been investigated systematically.
We combine publicly available data on methylcytosine content with the analysis of
nucleotide compositions of genomes and transcriptomes of 78 metazoan species to
trace the evolution of abundance and distribution of DNA methylation. The de-
pletion of CpG and the associated enrichment of TpG and CpA dinucleotides is
used to infer the intensity and localization of germline CpG methylation and es-
timate its evolutionary dynamics. These data provide evidence that the level of
methylation is positively correlated with genome size. In addition, transposons are
preferentially methylated in vertebrates and some invertebrates. Only jawed verte-
brates (gnathostomes), however, appear to exhibit methylation across nearly their
entire genomes. Concomitantly, evolution of a demethylation pathway and of novel
reader molecules enabled the usage of cytosine methylation for gene regulation. We
test the proposed relationship between genome size and methylation by measur-
ing total DNA methylation in Orthoptera insects with very different genome sizes:
House crickets, migratory locusts and meadow grasshoppers. As predicted, we found
a strong positive correlation between genome size and cytosine methylation in these
species. We suggest that the total amount of DNA methylation, representing a rela-
tively costly way of transcriptional regulation, is critically dependent on genome size
in metazoans. Since repetitive sequences are a major factor in determining genome
size, our findings imply that repeats are typically methylated, with the exception of
those species with very small genomes that have completely lost DNA methylation.
Keywords
CpG island, methylation, gene regulation