title: PO-CALC: a novel tool to correct common inconsistencies in the measurement of phenoloxidase activity.
abstract: A broad range of physiological and evolutionarily studies requires standard and robust methods to assess the strength and activity of an individual's immune defense. In insects, this goal is generally reached by spectrophotometrically measuring (pro-) phenoloxidase activity, an enzymatic and non-specific process activated after wounding and parasite infections. However, the literature surprisingly lacks a standard method to calculate these values from spectrophotometer data and thus to be able to compare results across studies. In this study, we demonstrated that nine methods commonly used to extract phenoloxidase activities (1) provide inconsistent results when tested on the same data sets, at least partly due to their specific sensitivity to the noise regularly present in enzymatic reaction curves. To circumvent this issue, we then (2) developed a novel, free and simple R-based program called PO-CALC and (3) demonstrated the robustness of its calculations for the different types of noises. Overall, we show that PO-CALC corrects overlooked though important inconsistencies in the measurement of phenoloxidase activities, and claim that its broad use would increase the significance and general validity of studies on invertebrate immunity.
authors.affiliation: Zoological Institute, Evolutionary Biology, Johannes Gutenberg University Mainz, Mainz, Germany. Electronic address: pkohlmei@students.uni-mainz.de.
authors.forename: Philip
authors.initials: P
authors.lastname: Kohlmeier
authors.affiliation: Beuth University of Applied Sciences, Berlin, Germany.
authors.forename: Heiko
authors.initials: H
authors.lastname: Dreyer
authors.affiliation: Zoological Institute, Evolutionary Biology, Johannes Gutenberg University Mainz, Mainz, Germany.
authors.forename: Joël
authors.initials: J
authors.lastname: Meunier
mesh_terms: D000818:Animals; D001000:Ants / Q000201:enzymology; D004156:Catechol Oxidase / Q000032:analysis*; D004792:Enzyme Precursors / Q000032:analysis*; D006458:Hemolymph / Q000201:enzymology; D007313:Insecta / Q000201:enzymology*; D014442:Monophenol Monooxygenase / Q000032:analysis*; D013712:Tenebrio / Q000201:enzymology
chemical_list: D004792:Enzyme Precursors; C038451:pro-phenoloxidase; D004156:Catechol Oxidase; D014442:Monophenol Monooxygenase
keywords: Hemolymph; Insects; Invertebrate; PO; PPO; Physiological immunity