title: Carnivorous pitcher plant uses free radicals in the digestion of prey.
abstract: A study of the involvement of free oxygen radicals in trapping and digestion of insects by carnivorous plants was the main goal of the present investigation. We showed that the generation of oxygen free radicals by pitcher fluid of Nepenthes is the first step of the digestion process, as seen by EPR spin trapping assay and gel-electrophoresis. The EPR spectrum of N. gracilis fluid in the presence of DMPO spin trap showed the superposition of the hydroxyl radical spin adduct signal and of the ascorbyl radical signal. Catalase addition decreased the generation of hydroxyl radicals showing that hydroxyl radicals are generated from hydrogen peroxide, which can be derived from superoxide radicals. Gel-electrophoresis data showed that myosin, an abundant protein component of insects, can be rapidly broken down by free radicals and protease inhibitors do not inhibit this process. Addition of myoglobin to the pitcher plant fluid decreased the concentration of detectable radicals. Based on these observations, we conclude that oxygen free radicals produced by the pitcher plant aid in the digestion of the insect prey.
authors.affiliation: National Institute of Education, Nanyang Technological University, Singapore, Republic of Singapore. tfchia@nie.edu.sg
authors.forename: Tet Fatt
authors.initials: TF
authors.lastname: Chia
authors.forename: Hnin Hnin
authors.initials: HH
authors.lastname: Aung
authors.forename: Anatoly N
authors.initials: AN
authors.lastname: Osipov
authors.forename: Ngoh Khang
authors.initials: NK
authors.lastname: Goh
authors.forename: Lian Sai
authors.initials: LS
authors.lastname: Chia
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002374:Catalase / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D005088:Exocrine Glands / Q000378:metabolism; D005609:Free Radicals; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007313:Insecta; D019684:Magnoliopsida / Q000033:anatomy & histology / Q000502:physiology*; D008954:Models, Biological; D009132:Muscles / Q000378:metabolism; D009211:Myoglobin / Q000737:chemistry; D010100:Oxygen / Q000378:metabolism*; D035261:Plant Components, Aerial / Q000502:physiology; D011506:Proteins / Q000378:metabolism*; D019097:Spin Trapping; D013481:Superoxides / Q000737:chemistry; D013997:Time Factors
chemical_list: D005609:Free Radicals; D009211:Myoglobin; D011506:Proteins; D013481:Superoxides; D006861:Hydrogen Peroxide; D002374:Catalase; D010100:Oxygen