Relationship between DNA methylation and expression levels of genes in Ad and ML stages of T. spiralis. (a, b) Average density (a) or percentage of methylation levels (b) within genes that were classified based on expression levels. The first class includes silent genes with no sequencing read detected, and the second to fifth classes cover expressed genes from the lowest 25% to highest 25%. In the curve graph, 2-kb regions upstream and downstream of each gene are divided into 100-bp intervals, and each gene was divided into 20 intervals (5% per interval). In the histogram graph, overall average (± standard error) methylation levels for genes are indicated.