tailieunhanh - Báo cáo khoa học: Glucose oxidase prevents programmed cell death of the silkworm anterior silk gland through hydrogen peroxide production

During pupal metamorphosis, the anterior silk glands (ASGs) of the silk-wormBombyx moridegenerate through programmed cell death (PCD), which is triggered by 20-hydroxyecdysone (20E). 20E triggers the PCD of the ASGs of day 7 fifth instar (V7) larvae but not that of V5 larvae. | IFEBS Journal Glucose oxidase prevents programmed cell death of the silkworm anterior silk gland through hydrogen peroxide production Hiroto Matsui1 Motonori Kakei2 Masafumi Iwami1 2 and Sho Sakurai1 2 1 Division of BiologicalSciences Graduate Schoolof NaturalScience and Technology Kanazawa University Japan 2 Division of Life Sciences Graduate Schoolof NaturalScience and Technology Kanazawa University Japan Keywords glucose oxidase hydrogen peroxide insect programmed cell death silk gland Correspondence S. Sakurai Division of Life Sciences Graduate School of Natural Science and Technology Kanazawa University Kanazawa 920-1192 Japan Fax 81 76 264 6215 Tel 81 76 264 6250 E-mail ssakurai@ Received 15 November 2010 revised 16 December 2010 accepted 21 December 2010 doi During pupal metamorphosis the anterior silk glands ASGs of the silkworm Bombyx mori degenerate through programmed cell death PCD which is triggered by 20-hydroxyecdysone 20E . 20E triggers the PCD of the ASGs of day 7 fifth instar V7 larvae but not that of V5 larvae. When V7 ASGs were cocultured with V5 ASGs in the presence of 20E neither culture of ASGs underwent PCD. The 20E-induced PCD of V7 ASGs was also inhibited when they were incubated in conditioned medium that was prepared by incubating V5 ASGs for 48 h an indication that V5 ASGs released an inhibitor of 20E-induced PCD during incubation. The inhibitor was purified from conditioned medium and identified as glucose oxidase GOD . GOD catalyzes the oxidation of glucose to gluconolactone and generates hydrogen peroxide as a byproduct. We found that hydrogen peroxide is the molecule that directly inhibits the action of 20E and may act to protect the ASGs from early execution of PCD during the feeding stage. GOD was localized in the inner cavity of the gland and was discharged to the outside of the ASGs with the silk thread at the onset of spinning. Thus the spinning behavior occurring at the .

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