Fig 4. Quantification of plant cell wall degrading enzyme activities in the fluids derived from head and foregut tissues of Ctenolepisma longicaudata and Thermobia domestica.

Fluids from head and foregut (FG) tissues of C. longicaudata and T. domestica fed on protein (BSA) or paper diet (see Materials and methods) were used in assays to detect A) endoglucanase activity against 4-nitrophenyl-β-D-cellopentaoside (BPNPG5), B) β-glucosidase activity against 4-nitrophenyl β-D-cellobioside (pNPC), C) β-xylosidase activity against 4-nitrophenyl β-D-xylpyranoside (pNPX), and D) polygalacturonase activity against pectin from citrus peel. Shown are the means and corresponding standard errors calculated from three biological and three technical replicates. Different letters above the bars indicate significant differences in the mean activity (P < 0.05). Units of specific enzyme activity are per mg of protein in all the graphs except in graph A) where it is expressed per g of protein. One unit of enzyme activity was defined as the amount of enzyme required to release 1 μmol of 4-nitrophenol from the respective substrate in all the graphs except in D), where it is 1 μmol of glucose.