Epigenetic underpinnings of freeze tolerance in the goldenrod gall fly Eurosta solidaginis and the goldenrod gall moth Epiblema scudderiana
The goldenrod gall fly Eurosta solidaginis and gall moth Epiblema scudderiana are cold hardy insects that inhabit stem galls on goldenrod plants and survive subzero temperatures during the winter. Eurosta uses a freeze tolerance strategy where it restricts the formation of ice to extracellular spaces and preserves vital intracellular functions. Epiblema supercools its bodily fluids to remain unfrozen below 0°C. This thesis examined the role of epigenetic enzymes in insect cold hardiness strategies. Cold and subzero temperature exposure in Eurosta resulted in upregulation of several DNA Methyltransferase (DNMT) enzymes, increases in DNMT and Histone Acetyltransferase (HAT) activities, and decreases in Histone Deacetylase (HDAC) and Ten-Eleven Translocation (TET) enzyme activities. Epiblema showed upregulation of several DNMT enzymes with concurrent decreases in DNMT, HAT, and HDAC activities and no change in TET activity. These findings suggest that epigenetic regulation of genes and histones underpins the winter survival strategies of these insects.