Glutathione peroxidase activity in insects: A reassessment

Abstract

In vertebrate species, cytotoxic H 2 0 2 and other lipid or organic hydroperoxides (ROOH) formed in aerobic metabolism are removed by a selenoprotein, glutathione peroxidase (GPOX). The GPOX activity in most rat tissues ranges from 100 to 1,000 units (1 unit = 1 nmol NADPH oxidized.mg protein-'.min-l), except for muscles (20-30 units). In contrast, GPOX activities of two strains of the housefly (Musca dornestica), cabbage looper (Eichoplusia ni), southern armyworm (Spodoptera eridania), and black swallowtail butterfly (fapilio polyxenes), were found to be in the range 2-12 units. Trivial GPOX activity was detected in the confused flour beetle (Eibolium confusurn). In the earthworm (Lumbricus terrestris), banana slug (Ariolirnax colurnbianus), and market squid (Loligo opalescens), the GPOX activity ranged from l to 5 units. Tissue selenium concentrations were about 500-1,000 ppb for adult M.dornestica, 600 ppb in T: confusurn, 32 ppb in T. ni, 17 ppb in S. eridania, and 31 ppb in F! polyxenes larvae. The form of selenium incorporated at such high levels in tissues of invertebrates such as M. dornestica remains an unresolved issue. Peroxidase activity of non-selenium glutathione-S-transferase (GT) against ROOH may compensate for the low GPOX activity. Catalase (CAT) has high activity and wide subcellular distribution in insects. This may be an evolutionary adaptation to GT's inability to catalyze the reduction of H 2 0 2 . The GT's peroxidase and CAT activities were not assessed for other invertebrate species, and warrants an investigation due to their reported low GPOX levels.

Antioxidant enzymes as biochemical defenses against phototoxin‐induced oxidative stress in three species of herbivorous lepidoptera

“…Very similar short-term results have also been obtained with the furanocoumarin xanthotoxin when used in diets fed T. ni [19]. Both quercetin and xanthotoxin have been shown to exhibit a time-and concentration-dependent inhibition of the GPOX activity observed in the southern armyworm S. eridania [37] although this could reflect an inhibition of GSH-transferase.…”

Does the grasshopper Chorthippus brunneus adapt to metal polluted habitats? A study of glutathione‐dependent enzymes in grasshopper nymphs

“…sure time. Moreover, the enzymatic response of an organism may be modified by gender, age, developmental stage, state of nutrition, habitat type and tolerance of various environmental toxins (Hunter et al, 1987;Ahmad et al, 1989;Schmidt et al, 1992;Dallinger, 1993;Augustyniak & Migula, 1996;Isman et al, 1996;Augustyniak & Migula, 2000). The factors mentioned above contribute to the extreme difficulty of describing trends in adaptation to polluted environments.…”

Effect of cold acclimation on the antioxidant defense system of two larval lepidoptera (noctuidae)

“…The relatively high GST activity in the larvae of both species during diapause suggests a possible, maybe an even more important, role of this enzyme in endogenous metabolic processes, which may not necessarily be connected with feeding, as is usually reported. The finding that GSH-Px (selenium-dependent enzyme) is absent in both Ostrinia and Sesamia larvae is not surprising, as it is conspicuously absent in a number of insect species [Ahmad et al, 1989]. In fact, there is strong support in the literature that GST (non-selenium-dependent enzyme) may substitute GSHPx in decomposing organic hydroperoxides, but not H 2 O 2 .…”