Pupal commitment and its hormonal control in wing imaginal discs |
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Authors: | Obara Y Miyatani M Ishiguro Y Hirota K Koyama T Izumi S Iwami M Sakurai S |
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Affiliation: | a Department of Biology, Faculty of Science, Kanazawa University, Kakumamachi, Kanazawa 920-1192, Japan b Department of Biology, Tokyo Metropolitan University, Minamiosawa, Hachioji 192-0397, Japan c Division of Life Sciences, Graduate School of Science and Technology, Kanazawa University, Kakumamachi, Kanazawa 920-1192, Japan |
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Abstract: | The timing of pupal commitment of the forewing imaginal discs of the silkworm, Bombyx mori, was determined by a transplantation assay using fourth instar larvae. The wing discs were not pupally committed at the time of ecdysis to the fifth instar. Pupal commitment began shortly after the ecdysis and was completed in 14 h. When the discs of newly molted larvae (0-h discs) were cultured in medium containing no hormone, they were pupally committed in 26 h. In vitro exposure of 0-h discs to 20-hydroxyecdysone accelerated the progression of pupal commitment. Methoprene, a juvenile hormone analog (JHA), did not suppress the change in commitment in vitro at physiological concentrations. Thus the wing discs at the time of the molt have lost their sensitivity to JH, and 20E is not a prerequisite for completion of pupal commitment. These results suggest that the change in commitment in the forewing discs may begin before the last larval molt. |
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Keywords: | 20-Hydroxyecdysone Juvenile hormone Methoprene Wing disc Commitment |
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