Comparing ethanol rehydration techniques: effects on spider morphology and DNA integrity

Ethanol curation plays a crucial role in preserving museum specimens, especially soft-bodied arthropods. Dehydration happens as a result of less than ideal storage and preservation conditions. If rehydration is desired for a specimen, then effective rehydration methods must be investigated and compared. The impact different rehydration techniques have on specimen tissues has been studied in vertebrates but is less explored in arthropods. Additionally, how these techniques impact the DNA of dehydrated arthropod specimens has not been assessed. In this study, we investigated the impact of two rehydration approaches on dehydrated spiders from the same donation. We used a gradual ethanol rehydration “Step-Up” method, and a heat-accelerated, or Heat-Rehydration, method. To determine which approach was most effective for restoring dehydrated spiders in ethanol, we assessed spider morphology for damage, DNA yield, and DNA integrity. We found that all desiccated and rehydrated spiders, regardless of treatment choice, displayed varying levels of tissue desiccation and separation of the abdomen and legs. The Step-Up method was more consistent than the Heat-Rehydration method in rehydrating tissues and reducing the separation of tissues from the abdomen. Overall, we found a significant difference in abdominal tissue separation between our controls and treatments but no significant difference when assessing damage to pedipalps. Additionally, DNA capture from all specimens was low and significantly degraded compared to a positive control group. Our recommendations for museum collections managers are to consider the fragility of dehydrated materials in deciding what rehydration technique to use and to preferentially extract DNA from other material if possible.