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We therefore postulate that the metamorphosis of holometabolous insect larvae into adults involves fundamental changes in gene expression, and that epigenetic mechanisms may be involved in this process. Many if not all developmental processes involve the orchestrated large-scale transcriptional reprogramming of genes. A fundamental question in developmental biology is how the same genome can generate morphologically and ecologically distinct phenotypes, such as the caterpillars, pupae, and imagoes in the order Lepidoptera. The complete metamorphosis of holometabolous insects involves a pupal stage, during which larval tissues and organs are remodeled and/or replaced by the structures required in the imagoes. Transformation from one morphologically distinct phenotype to another during development is known as metamorphosis. sexta larvae and adults suggest that complete metamorphosis involves epigenetic modifications associated with profound transcriptional reprogramming, involving approximately half of all the genes in this species. The distinct sets of methylated genes in M.

Interestingly, genes encoding histone acetyltransferases and histone deacetylases were differentially methylated in the larvae and adults, indicating there is crosstalk between different epigenetic mechanisms. We also identified 4.946 loci and 4.960 regions showing stage-specific differential methylation. sexta genes (3.729) were upregulated in last-instar larvae relative to the adult moth, whereas 26 % (4.077) were downregulated. Expression analysis revealed that 24 % of all known M. Bisulfite sequencing indicated a generally low level of DNA methylation with a unimodal CpG O/E distribution. Using the tobacco hornworm ( Manduca sexta), a powerful model for the analysis of insect evolution and development, we conducted a genome-wide comparative analysis of gene expression and DNA methylation in caterpillars and adults to determine whether complete metamorphosis has an epigenetic basis in this species. The transition between morphologically distinct phenotypes during complete metamorphosis in holometabolous insects is accompanied by fundamental transcriptional reprogramming.