The toxicity of oxybenzone (benzophenone-3; BP-3), a UV filter present in coral reef waters at toxic concentrations, has been incompletely characterized for oxidative stress responses in adult cnidarians. In order to examine this, Aiptasia pallida (an anemone commonly used as a coral research model) was exposed to oxybenzone at concentrations of 0.02, 0.2, 2.0, and 3.0 mg/L for 5, 10, and 30 days (n = 4 tanks per treatment). Catalase (CAT) and superoxide dismutase (SOD) activity, glutathione levels, and the alkaline comet assay (% DNA in tail) were analyzed. CAT increased significantly at all concentrations and timepoints, with 80.6% maximum induction at 2.0 mg/L on Day 30 and a LOEC of 0.02 mg/L. SOD showed no significant response at any timepoint. The levels of glutathione increased at Day 5 for the two highest concentrations, but decreased at Day 10 for 3.0 mg/L. Genotoxic effects were significant at Days 5 and 10, with a threshold between 0.02 and 2.0 mg/L. A significant positive correlation between group mean CAT activity and % DNA in the tail contrasted with a null SOD–DNA association, identifying hydrogen peroxide, not superoxide, as the proximate genotoxic driver in adult cnidarian tissue. These results indicate that oxybenzone induces oxidative stress responses in A. pallida.

Matrix selection and application is a crucial step in obtaining meaningful results with matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI). Most instruments have a large spatial, and data with adequate spatial resolution can frequently be obtained on a benchtop instrument. The matrix application workflow has been optimized for the imaging of the earthworm (Eisenia hortensis), after exposure to various statins, a class of blood lipid-lowering agents. Lipids are nonpolar, often neutral molecules, making them difficult to ionize, and heightening the need for matrix optimization. The matrices 2,5-dihydroxybenzoic acid (DHB), α-cyano-4-hydroxycinammic acid (CHCA), 1,5-diaminonaphthalene (DAN), and 3,5-dimethoxy-4-hydroxycinnamic acid (sinapinic acid; SA) were studied. Samples were also washed in the ammonium salts of acetate, bicarbonate, formate, sulfate, or water as a control to enhance ionization and improve spatial resolution. A successful matrix for MSI is one that demonstrates homogenous tissue coverage, ionization of the analytes of interest, and does not require excessive laser power for ionization. All matrices showed sufficient tissue coverage; however, CHCA yielded unambiguous images of cholesterol and yielded sufficient signal over the lipid mass range (400–1,000 m/z), indicating that it successfully ionized endogenous lipids. Following additional optimization, the application of 50 mL of 10 mg/mL CHCA following a 5 s salt ammonium sulfate salt wash proved most successful for improving lipid ionization and enhancing spatial resolution.