Study On The Physiological And Biochemical Response And Differentially Expressed Proteome Under UV Stress In Helicoverpa Armigera

The cotton bollworm, Helicoverpa armigera (Hubner) (Lepidoptera:Noctuidae) is one of the most serious insect pest in China and neighboring contries. The moths of this nocturnal insect display a conspicuous positive phototactic behaviour to light stimuli, and are especially sensitive to Ultraviolet (UV) light. In the present study, we study on the physiological and biochemical response and differentially expressed proteome under UV light irradiation stress in H. armigera adults. Main results were summarized as follows:1. Response of the antioxidant system of H. armigera adults to UV light stressWe test the hypothesis that one of the effects of UV light irradiation is to increase oxidative stress on insects. The effects of UV light irradiation on total antioxidant capacity and the activities of superoxide dismutase (SOD), catalase (CAT), peroxidases (POX), glutathione-S-transferase (GST) and glutathione reductase (GR) were investigated in H. armigera adults. The adults were exposed to UV light for various time periods (0,30,60 and 90 min). We found that exposure to UV light for 30 min resulted in increased total antioxidant capacity and the activities of SOD, CAT, POX and GST. When the exposure time lasted for 60 and 90 min, the activities of CAT and GST remained significantly higher than the control. However, the antioxidant capacity and SOD activity returned to control levels, and POX activity decreased at 60 and 90 min. Our results confirm the hypothesis that UV light irradiation increases the level of oxidative stress in H. armigera adults.2. Effects of UV light stress on the activities of acetylcholinesterase and carboxylesterase in H. armigera adultsWe analyse the relation between UV light stress and the activities of acetylcholinesterase (AChE) and carboxylesterase (CarE) in H. armigera adults. The effects of UV light irradiation on the activities AChE and CarE were investigated in H. armigera adults. The adults were exposed to UV light for various time periods (0,30, 60 and 90 min). AChE activity of adults exposed to UV light was reduced in comparison with the control adults, and a significant decrease was found at 30 min of exposure. We found decreaded CarE activity in H. armigera adults exposed to UV light for 30,60 and 90 min in comparison with the control. We assume that the activities of AChE and CarE in insects may be influenced by other environmental stress, except for insecticides that have been reported.3. Effects of UV light stress on several isozymes in H. armigera adultsTo study the effects of UV light stress on esterase, POX, and CAT isozymes in H. armigera adults, we carried out isozyme electrophoresis. When exposed to UV light irradiation, esterase isozyme changed mainly in the number and activity of isozyme. At 30 and 60 min exposure, the intensity of isozyme bands E4, E9 and E10 were enhanced, E2 and E8 were decreased. The bands El, E5, E7 and Ell disappered after UV light irradiation, E3 and E6 were new patterns. At the longest exposure time (90 min), the intensity of isozyme bands E4 and E9 E10 were enhanced, E2 and E8 were decreased. The bands E1, E5 and E7 disappered after UV light irradiation, E3 and E6 were new patterns. H. armigera adults showed 6 POX bands. The intensity of POX band P5 was enhanced in adults following exposure to UV light for 30,60 and 90 min. H. armigera adults showed 2 CAT bands. The intensity of band C1 was enhanced in adults following exposure to UV light irradiation for 30,60 and 90 min. The intensity of band C2 was decreased at 30 and 90 min of exposure in comparison with the control. These processes may be mirrored in insect physiological adaptation.4. A proteomic analysis of H. armigera adults after exposure to UV light irradiationTo gain a better understanding of the response of H. armigera adults to UV light irradiation, we carried out a comparative proteomic analysis. Three-day-old adults were exposed to UV light for 1 h. Total proteins were extracted and separated by two-dimensional gel electrophoresis. More than 1200 protein spots were reproducibly detected, including 12 that were more abundant and 21 less abundant. Mass spectrometry analysis and database searching helped us to identify 29 differentially abundant proteins, including mitogen-activated protein kinase, ste20-like kinase CG40293-PA, isoform A, ADP-ribosylation factor guanine nucleotide-exchange factor 2 (brefeldin A-inhibited), isoform CRA_a, zinc finger protein 768, PREDICTED:similar to PPAR-alpha interacting complex protein 285, Beta subunit of type I geranylgeranyl transferase, putative octanoyltransferase, mitochondrial, heat shock protein hsp21.4, PREDICTED:similar to catalase, enolase, H+ transporting ATP synthase beta subunit isoform 1, H+ transporting ATP synthase beta subunit isoform 2, Prenylcysteine oxidase 1, Adenosine deaminase-like protein A, 3-hydroxy-3-methylglutaryl-CoA reductase, farnesyl-pyrophosphate synthetase, actin (Fragment), myosin heavy chain, muscle myosin heavy chain, olfactory receptor-like receptor, lysozyme C, structural maintenance of chromosome, putative, etc. The identified proteins were categorized into several functional groups including signal transduction, RNA processing, protein processing, stress response, metabolisms, and cytoskeleton structure, etc.