Threading together a map of silkworm DNA modifications

A study published this week in Nature Biotechnology reveals that DNA methylation across the silkworm genome is much less common than in mammals and plants. Understanding methylation ― a type of DNA modification that helps determine which genes are switched on and which are switched off ― can help in our understanding of the insect lifecycle.

To investigate the level of DNA methylation in the silkworm, Jun Wang and colleagues employed a next-generation sequencing-based approach to create a high-resolution map of methylated and unmethylated cytosines ― one of the four DNA bases ― in the silkworm genome. Their results suggest that the genome from cells of the silkworm silk gland contains about fifty-fold fewer methylated cytosines than is found in the genomes of human or plant cells.

Silkworm genes containing higher amounts of modified cytosines were confirmed to show higher levels of gene expression, but modifications in other regions of the genome may have different roles in insects compared with mammals and plants.