Patterns of puffing activity in the salivary gland chromosomes of Drosophila
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- Ashburner, M. Chromosoma (1972) 38: 255. doi:10.1007/BF00290925
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A technique for the short term organ culture of larval salivary glands of D. melanogaster is described. Cultured Puff Stage 1 glands respond to 20-OH ecdysone by initiating the cycle of puffing activity characteristic of late larval development and puparium formation. This puffing cycle involves the sequential activation of at least 125 puffs. Their response to ecdysone allows these puffs to be divided into 3 main classes: a) PS1 puffs that regress (e.g. 25AC); b) puffs activated very rapidly (within 5 min) (e.g. 23E, 74EF, 75B) and c) puffs activated only after longer periods (>4 h) (e.g. 62E, 78D, 22C, 63E and 82F). The detailed behaviour of representatives of each class is described. These data support Clever's distinction of ‘early’ and ‘late’ ecdysone responsive sites.