אסיף מאגר המחקר החקלאי

Depressed RNA synthesis in the early stages of the larval-pupal transformation of Lepidoptera: The role of 20-hydroxyecdysone

Year:

1988

Source of publication :

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Volume :

34

Co-Authors:

Shaaya, E., Volcani Center, Institute of Technology, Bet-Dagan 50-250, Israel
Riddiford, L.M., Department of Zoology, University of Washington, Seattle, WA 98125, United States

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Abstract:

Changes in RNA synthesis in the epidermis of last larval instar larvae of Ephestia cautella and Manduca sexta (Lepidoptera) were followed. For about 30 h just prior to wandering stage, total RNA synthesis was depressed. Analysis of RNA showed that the synthesis of all RNA species was decreased; in Ephestia this change caused a reduction of about 17% of the bulk RNA in the cells. Following this period, the wandering stage, pupally committed epidermal cells synthesize a new type of RNA termed hetero-disperse nuclear RNA (HnRNA), then as the prepupal period begins a marked increase in rRNA synthesis was observed. Ten micrograms methoprene, a juvenile hormone analogue, delayed the larval-pupal transformation and prevented these changes in RNA synthesis. In vitro 50 ng/ml 20-hydroxyecdysone was necessary and sufficient to cause the depression of RNA synthesis in day-1. Manduca epidermis. Moreover, the change to pupal commitment induced by 24 h exposure of day-2 epidermis to 500 ng/ml 20-hydroxyecdysone also caused a significant increase in total RNA synthesis. © 1988.

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