Superoxide dismutase activities in the midgut of Helicoverpa armigera larvae: identification and biochemical properties of a manganese superoxide dismutase

Abstract

Insects possess a complex network of enzymatic antioxidant systems protecting against reactive oxygen species generated during stress. Superoxide dismutases (SODs) are vital antioxidant enzymes converting superoxide into oxygen and hydrogen peroxide. Helicoverpa armigera is a polyphagous insect and has developed resistance to various phytochemicals and pesticides. Although SODs are studied in several insect species, their characterization has been reported in only a few insect species. Here, we attempted to identify and characterize SOD activity from H. armigera. Electrophoretic separation followed by nitroblue tetrazolium staining revealed the presence of five SOD activity isoforms in the midgut of H. armigera larvae. Total SOD activity was measured at the different larval developmental stages and found maximum at fourth instar and further declined at sixth instar. Total SOD activity was significantly increased by metal ions Mn, Fe, Zn, and Cu and reduced by Ca and Pb. The isoform with highest activity was identified as manganese SOD (MnSOD) because it was found insensitive to H 2 O 2 . The identified MnSOD was partially purified and characterized. After gel filtration chromatography, specific activity of the purified enzyme was found to be 6,348.0 U/mg/min with 26.61% yield. The molecular mass of purified enzyme was calculated to be ∼29.3 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The optimum pH and temperature for the SOD activity were found to be around 11 and 60°C, respectively. The study could be useful to further understand the functional significance of SODs in the antioxidant mechanism of H. armigera.

Ethno-entomotherapeutic and metabolite profiling of Coridius chinensis (Dallas), a traditional edible insect species of North-East India

“…The study demonstrated significant antioxidant activity by performing different assays namely SOD, DPPH, and GST in the hydro-alcoholic extract of C. chinensis . Superoxide dismutase (SOD) is one of the key enzymes of insect antioxidant system 25 . The importance of SOD in therapeutic potential and physiological have already been mentioned in several reports.…”

Transcriptome of the Maize Leafhopper ( Dalbulus maidis ) and Its Transcriptional Response to Maize Rayado Fino Virus (MRFV), Which It Transmits in a Persistent, Propagative Manner

“…However, this production could be degraded by superoxide dismutase [Cu-Zn]. Superoxide dismutases are key antioxidant enzymes converting superoxide into oxygen and hydrogen peroxide ( 50 ). We found that superoxide dismutase was significantly upregulated after leafhopper exposure to MRFV at 4 h, suggesting that ROS production may be disarmed by 4 h after virus entrance vector.…”

Interspecies isobaric labeling-based quantitative proteomics reveals protein changes in the ovary of Aedes aegypti co-infected with ZIKV and Wolbachia

“…ROS accumulation activates the mosquito Toll immune pathway, resulting in the production of AMPs (Pan et al, 2012). Possibly as a result of this ROS amount, Cu-Zn superoxide dismutase (SOD) proteins (AAEL019937 and AAEL025388) were upregulated comparing WZ with W, Z and A. SODs are an important antioxidant enzymes that convert superoxide into oxygen and hydrogen peroxide (Park et al, 2012;Lomate et al, 2015) and it is also related to protecting insects' ovaries during diapauses (Sim & Denlinger, 2011). Besides ROS-mediated immune response, a DEAD box ATP-dependent RNA helicase (AAEL004978) was upregulated in coinfection.…”