Antioxidant enzyme activities in subcellular fractions of larvae of the black swallowtail butterfly, Papilio polyxenes

Abstract

The black swallowtail butterfly, Papilio polyxenes, larvae are specialized feeders of pro‐oxidant rich plants of Apiaceae and Rutaceae. An important defense against toxic forms of oxygen species generated by ingestion of the pro‐oxidants, are the antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), GSH‐dependent glutathione peroxidases (selenium‐dependent glutathione peroxidase [GPOX] and peroxidase activity of selenium‐independent glutathione‐S‐transferase [GTpx]), and glutathione reductase (GR). The subcellular distribution of these enzymes in black swallowtail larvae was investigated and was found to resemble the patterns described for larvae of two other lepidopteran species: the southern armyworm, Spodoptera eridania, and the cabbage looper, Trichoplusia ni. The confinement of SOD in the cytosol and mitochondria was typically eukaryotic, but the relative proportion (1:1) was markedly different from the mammalian pattern (4:1; cytosol:mitochondria). The most obvious difference between the black swallowtail and other lepidoptera as a group, and mammalian species, is in very wide intracellular distributions of CAT, GTpx, and GR in insect species. Insects possess very low levels of a GPOX‐like activity which reduces both H2O2 and organic peroxides. Consequently, insects have elaborate activities with a wide subcellular distribution of both CAT which decomposes H2O2, and GTpx which decomposes organic peroxides. The reduction of peroxides is dependent on GSH, which in this process is oxidized to GSSG. GR which reduces GSSG to GSH is also of wide subcellular distribution, analogous to the distribution pattern of GTpx.

Antioxidant enzymes in the honey bee, Apis mellifera

“…Evidence for the dual localization and the existence of SODs with different metal content has also been reported for several lepidopteran species (Ahmad et al, 1988a(Ahmad et al, , 1988b(Ahmad et al, , 1990(Ahmad et al, , 1991.…”

“…Thus, CAT may have been lost during the centrifugation of the tissue homogenates. However, soluble CAT has been found in mammalian (Masters et al, 1986) as well as insect species (Aucoin et al, 1991;Joanisse and Storey, 1996), and larval homogenates of lepidopteran species have been shown to contain substantial CAT activities in mitochondrial, microsomal and cytosol fractions (Ahmad et al, 1988a(Ahmad et al, , 1988b(Ahmad et al, , 1990. The midgut of honey bee workers contains CAT in peroxisomal as well as soluble fractions (Jimenez and Gilliam, 1996).…”

Food utilization and antioxidant enzyme activities of black swallowtail in response to plant phototoxins

“…Ivie et al [35] found that 5% of labeled xanthotoxin still remained in the body of P. polyxenes larvae 24 h after administration of a single dose. Since furanocoumarins produce photodynamically toxic oxygen species such as singlet oxygen and superoxide radicals in the presence of activating wavelengths [2], unmetabolized furanocournarins would be expected to produce toxic oxygen species [17,18]. Ingested harmine, despite its feeding deterrent property, may well be detoxified in P. polyxenes, since harrnine did not affect the nutritional efficiency of the insect.…”

“…All aerobic organisms possess antioxidant enzymes to detoxify oxyradicals generated from endogenous activities related to respiration and other metabolism [14]. However, in some phytophagous insects, such as P. polyxenes, which are constantly exposed to prooxidants like plant phototoxins during feeding, antioxidant enzymes may be especially important as a detoxification system [15][16][17][18][19]. Increased oxidative stress owing to ingested phototoxins may affect the levels of antioxidant enzymes.…”