Wu N, Liang C, DiBartolomeis S M, Smith H S, Gerbi S A
Division of Biology and Medicine, Brown University, Providence, Rhode Island 02912.
Dev Biol. 1993 Nov;160(1):73-84. doi: 10.1006/dbio.1993.1287.
DNA amplification for two major DNA puffs (II/2B and II/9A) of the fungus fly Sciara coprophila increases steeply from 17 to 19 days after hatching (18 degrees C), resulting in almost 20-fold more DNA at these loci in mature larval salivary glands than in adult tissues. At 19 days after hatching when gene amplification reaches a plateau, there is a burst in the amount of mRNA encoded by these two DNA puffs. Expansion of the two puffs coincides with the increase in transcription rather than reinitiation of DNA replication. In contrast, an RNA puff (III/9B) undergoes no DNA amplification, and the burst in RNA produced by this locus occurs slightly later, at 20 days after hatching. The progression of cytological puffing and associated molecular events of DNA amplification and transcription correlate with features of the external phenotype of the larvae, especially the number of pigment granules in the eyespots that are the anlage to the adult eyes. The sequential and coordinated regulation of DNA puff replication and transcription is discussed.
粪蝇（Sciara coprophila）的两个主要DNA胀泡（II/2B和II/9A）的DNA扩增在孵化后17至19天（18摄氏度）急剧增加，导致成熟幼虫唾液腺中这些位点的DNA比成年组织中多近20倍。在孵化后19天，当基因扩增达到平台期时，这两个DNA胀泡编码的mRNA量会激增。这两个胀泡的扩展与转录增加相吻合，而不是DNA复制的重新起始。相比之下，一个RNA胀泡（III/9B）不进行DNA扩增，该位点产生的RNA激增稍晚出现，在孵化后20天。细胞学胀泡的进展以及DNA扩增和转录相关的分子事件与幼虫外部表型特征相关，特别是眼点中色素颗粒的数量，眼点是成虫眼睛的原基。本文讨论了DNA胀泡复制和转录的顺序和协调调控。
