Cell determination in Drosophila with paradoxical genotypes☆

[摘要] AparadoxicalgenotypeforDrosophilamelanogasterisconstructedbycombiningtwohomeoticmutations,whichcausecontradictorytransformationsofthefirstabdominalsegmenttometathoraxandsecondabdominalsegment.Theresultingconflictingeneticinstructionsisresolvedbytheindividualcellswhichnormallygiverisetothefirstabdominalsegment.Eachcellelectstofollowonlyonesetofinstructionsanddeterminestoeithermetathoraxorsecondabdominalsegment.Thechoicebetweenpathwayscanbecharacterizedbythe“determinationequilibrium,”whichisameasureoftheprobabilitythatnocellinapresumptivefirstabdominalhistoblastdeterminestosecondabdominalsegment.Thedeterminationequilibriumallowsaquantitativeassessmentofgenotypicandphysiologicalfactorswhichcaninfluencetheprobabilityofadeterminativedecision.Theseresultsarediscussedfromthepointofviewoftheabstractnatureofdeterminativedecisionsandfromthepointofviewofthemechanismsinvolved.

[学科分类] 生物科学（综合）