(二)基因活动的调控 1差别基因活动的细胞学及生化证据 87c87A 姐6e .inart by a 40-minute exposure to 37'C. (a) Control experiment with no heat shock. (b) Puffs formed after heat shock. (From Ash- (b) burner and Bonner, Cell 17: 241, 1979. Copyright M.I.T. Press, Balbiani rings in salman gland chromosomes from the midge Chiron- omus. (a) Electron icrograph showring risible Balbiani rings(arrows). (b)auto- radiograph after ina bation in medium conlaining ' H-labeled uracil The incorporeal of the 'H-lubeled uridine shows that heauy RNA synthess is occurring Im the balbar ring.(Part a by U/rich Clever, part b by Claws Pelling, Mar Planck Institute fo Biolog)(二)基因活动的调控 1 差别基因活动的细胞学及生化证据