3.2 Differentially expressed genes
We compared gene expression between current-day and elevated CO2 conditions for the CNS and eyes separately. There was more variance in the eyes than the CNS (Figure 2A). In the CNS, we identified 25 differentially expressed genes (DEGs) between current-day and elevated CO2 conditions; 14 upregulated and 11 downregulated with elevated CO2. In the eyes, there were eight DEGs; five upregulated and three downregulated at elevated, compared to current-day, CO2 conditions (Figure 2B). Two genes were significantly upregulated with elevated COin both the CNS and eyes; one essential for autophagy (ykt6) and another poorly characterised gene (fam204a). In both tissues, the DEGs play roles in neurotransmission (CNS: folh1, syvn1-bslc2a13, celsr3, eyes: maoa, slc18a1cbs), immune function (CNS: psenen, syvn1-b, map4k5, tf, nme6, map1l3ca/b, eyes: pglyrp2cbs, maoa), the oxidative stress response (CNS: tfcyb561d2, syvn1-b, chrac1, ykt6, eyes: cbs, ykt6), and transcription regulation (CNS: nme6, chrac1, znf271, eyes: gtf2e2 ) (Table S6).