Dual function of the region-specific homeotic gene spalt during Drosophila tracheal system development.
We report that the region-specific homeotic gene spalt affects the Drosophila tracheal system at two different stages of embryonic development. Both lack-of-function and gain-of-function experiments show that blastodermal spalt activity restricts tracheal development to 10 bilaterally positioned pairs of tracheal placodes in the trunk region by repressing placode formation in parasegments 2, 3 and 14. The results suggest that the activity of the zinc-finger type transcription factor encoded by spalt suppresses the molecular pathway that establishes tracheal development. spalt function is also necessary for the directed migration of the dorsal trunk cells, a distinct subset of tracheal cells. This process is a prerequisite for the formation of the dorsal trunk generated by fusion of adjacent tracheal metameres into a common tubular structure. The directed cell migration, in which spalt gene function participates, seems to be independent of branch fusion and general tracheal cell migration processes.
Kühnlein
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Abteilung Molekulare Entwicklungsbiologie, Max-Planck-Institut für Biophysikalische Chemie, Göttingen, Germany.
Schuh
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D000818:Animals; D002465:Cell Movement; D003001:Cloning, Molecular; D004330:Drosophila / Q000196:embryology* / Q000235:genetics; D029721:Drosophila Proteins; D004625:Embryo, Nonmammalian / Q000502:physiology* / Q000648:ultrastructure; D005260:Female; D005801:Genes, Homeobox / Q000235:genetics; D017344:Genes, Insect / Q000235:genetics*; D006360:Heat-Shock Proteins / Q000235:genetics; D018398:Homeodomain Proteins; D007150:Immunohistochemistry; D007301:Insect Hormones / Q000032:analysis / Q000235:genetics*; D008297:Male; D008855:Microscopy, Electron, Scanning; D009024:Morphogenesis; D014132:Trachea / Q000737:chemistry / Q000196:embryology*; D014157:Transcription Factors / Q000032:analysis / Q000235:genetics*; D016335:Zinc Fingers / Q000235:genetics*
D029721:Drosophila Proteins; D006360:Heat-Shock Proteins; D018398:Homeodomain Proteins; D007301:Insect Hormones; D014157:Transcription Factors; C085793:salm protein, Drosophila