Gene amplification in dipteran chromosomes.

Abstract

The giant polytene chromosomes characteristic of many Dipteran cells allow fundamental nuclear processes occurring during development to be directly visualized. Polytene chromosomes afford a detailed picture of “large-scale” structures within developmentally regulated interphase cells — features extending over more than about 5–10 kb of chromosomal DNA. Structures, such as chromomeres, constrictions, and puffs, must be disrupted for biochemical studies and cannot currently be reconstituted. However, following Wolfgang Beermann’s recognition that polytene chromosome puffs were manifestations of developmentally regulated gene expression, much progress has been made in understanding the molecular basis of gene transcription. Genetic studies have identified small regulatory regions located near tissue-specific genes that mediate developmental control (see Rubin 1985). However, the functional significance of associated large-scale structures, such as puffs, remains poorly understood.KeywordsSalivary GlandPolytene ChromosomeFollicle CellSalivary Gland ChromosomeDifferential ReplicationThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.