Effects on digestive enzyme activities in the house crickets Acheta domesticus exposed to graphene oxide in food for several generations

Abstract

Increasing usage of nanoparticles or nanomaterials may lead to their release into the environment. The toxicity of these structures, classified as contaminants of emerging concern, is not yet sufficiently understood. However, as in the case of other environmental stressors, the effects of exposure to them should be analyzed on a multigenerational scale to predict the consequences for exposed populations. Therefore, this project aimed to assess the impact of graphene oxide (GO) nanomaterial on digestive enzyme activities in the house cricket Acheta domesticus as a model species, depending on GO concentration (0.2 or 0.02 µg·g^-1 dry weight of food), previous selection for longevity and the number of generations (1-5) that have occurred since the beginning of exposure. The last and sixth generations were insects for which GO was withdrawn from the diet (recovery generation). Enzymatic activity was tested using API Zym kit modified for spectrophotometric reads. The tests revealed that GO intervenes with some digestive enzymes. Moreover, the effects of GO depend on the population's previous selection for longevity. The impact of mechanisms mitigating the consequences of aging supports the possible tolerance to GO intoxication. It demonstrated itself in diverse patterns of multigenerational response to GO in wild and long-lived insects. Also, multigenerational exposure revealed the 'third generation' effect. Finally, the impact of GO elimination depended on the concentration of nanomaterial used for the tests. Also, the potential impact of concentration-dependent agglomeration of GO in the context of hormesis has been discussed.

Keywords: Nanomaterial; dephosphorylating enzymes; esterolytic enzymes; glycolytic enzymes; proteolytic enzymes.