Gap genes and gradients--the logic behind the gaps

Bioessays. 1991 Jun;13(6):261-8. doi: 10.1002/bies.950130602.


Gap genes stand at the top of the zygotic segmentation hierarchy in Drosophila. Their expression domains are set up by a combination of maternal regulatory signals and interactions among themselves. In addition, these regulatory pathways are partially redundantly specified by the maternal and zygotic genomes, or by multiple zygotic gene products. The gap genes code for transcription factors which exert their function by forming short-range morphogenetic gradients; differential concentrations of these transcription factors can either act as activators or as repressors for the expression domains of neighboring genes. It is possible to view the gap genes as a system of genes that subdivides the embryo by forming an activation-repression cascade proceeding from anterior towards posterior.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Drosophila melanogaster / embryology
  • Drosophila melanogaster / genetics*
  • Embryo, Nonmammalian / physiology
  • Embryo, Nonmammalian / ultrastructure*
  • Gene Expression Regulation*
  • Genes*
  • Genes, Homeobox
  • Larva / ultrastructure
  • Models, Genetic
  • Morphogenesis
  • Phenotype
  • Repressor Proteins / genetics
  • Repressor Proteins / physiology
  • Transcription Factors / genetics*
  • Transcription Factors / physiology
  • Zygote / physiology


  • Repressor Proteins
  • Transcription Factors