Fig. 1

Transcriptomes pairwise comparisons reveal a specific pattern of gene expression in L. stagnalis CNS. A For transcriptome analysis, mRNA was extracted from the CNS of young (3 months old), adult (6 months old), and old (18 months old) snails. For each age group, four different biological replicates (n = 4), each with mRNA samples from the CNS of 10 snails, were used. B Venn diagram showing the significantly differentially expressed genes in each pairwise comparison and the overlap among them. The diagram clearly shows that young CNS transcriptome has more significantly differentially expressed genes compared to adult and old. (FDR adjusted p-value p < 0.05; log2 fold change > |1|). C Volcano plot of each pairwise comparison. The plots are color-coded based on the log2 fold change (green dots), and corrected p-value (blue dots). Red dots highlight genes that are significant and whose expression is highly changed (FDR adjusted p-value p < 0.05; log2 fold change > |1|). Volcano plots of the comparison between adult and old CNS transcriptome shows less differentially expressed genes, by either p-value or log2 fold-change, compared to the pairwise comparison of young versus adult or old transcriptome. D, E Heatmap of the most differentially expressed genes in all pairwise comparisons (FDR adjusted p-value p < 0.05) and the genes with the highest variance (top 2000 genes), respectively. Both heatmaps show a distinct pattern of gene expression in the CNS transcriptome of young snails compared to adult and old