Figure 2: Transcriptome and methylome analysis of locust phase change.

(a) Locust phase polyphenism. The solitarious phase individual is relatively inactive and cryptically coloured, but gregarious phase individual actively swarms and is conspicuously coloured. (b) Relative CG methylation level of different genomic regions through a RRBS method. The ratio was defined as the number of methylated CG to the number of total CG, and was calculated using the CG on the reads that map to the defined regions. The results were derived from the data of brain samples of fourth-instar locust nymphs. (c) Functional classification of differentially methylated genes (DMGs) of brain tissues between solitarious and gregarious fourth-instar female nymphs. Genes with at least four differentially methylated CG sites were thought of as DMGs. (d) Gene ontology enrichment of differentially expressed genes (DEGs) in brain tissues of fourth-instar locust nymphs over time for the gregarization (crowding of solitarious locusts (CS)) and solitarization (isolation of gregarious locusts (IG)) processes (4, 8, 16, 32 and 64 h) compared with controls. The rightmost column denotes the comparison between the solitarious and gregarious control. The up- and downregulated genes are coloured as red and blue, respectively. The length of the bar denotes the −log10 of the adjusted P-value of the enrichment significance (Fisher’s exact test or χ²-test). A, activity; Mit, mitochondrion; P, process. (e) Model for molecular regulation of synaptic plasticity involved in locust phase change. In this model, DEGs, DMGs or differentially spliced genes (DSGs) were found for different components. MAP, microtubule-associated protein.