Synchronized endocytosis studied in the oocyte of a temperature-sensitive mutant of Drosophila melanogaster.
This study demonstrates that endocytosis in the oocyte of Drosophila melanogaster is reversibly blocked at the stage of pit formation by the temperature-sensitive, single-gene mutant, shibirts1. Uptake of horeradish peroxidase conjugated with wheat-germ agglutinin was observed to be normal in mutant oocytes at 19 degrees C, but was blocked at 29 degrees C. After 10 min at 29 degrees C, there was a build-up of coated pits along invaginations of the plasma membrane. Also, the endosomal compartment consisting of tubules, bulbs, and small yolk spheres, disappeared. Lowering the temperature to 19 degrees C after 10 min at 29 degrees C released a synchronized wave of endocytosis into a cytoplasm cleared of uptake-related organelles. By observing this synchronized wave after exposure to 19 degrees C for varying durations, we determined that endocytosis proceeds as follows: coated pits/vesicles----tubules----small yolk spheres----mature yolk spheres. The observations suggest that these organelles transform one into another within this sequence.
Division of Neurosciences, Beckman Research Institute of the City of Hope, Duarte, California 91010.
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Tsuruhara
J H
JH
Koenig
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K
Ikeda
D000818:Animals; D004331:Drosophila melanogaster / Q000235:genetics* / Q000502:physiology; D004705:Endocytosis; D006735:Horseradish Peroxidase / Q000493:pharmacokinetics; D009154:Mutation; D009865:Oocytes / Q000502:physiology* / Q000648:ultrastructure; D013696:Temperature; D014819:Vitellogenins / Q000493:pharmacokinetics*; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D014909:Wheat Germ Agglutinins / Q000493:pharmacokinetics
D014819:Vitellogenins; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D014909:Wheat Germ Agglutinins; D006735:Horseradish Peroxidase