Purification and site of synthesis of <i>Aedes aegypti</i> yolk proteins

Abstract

Abstract The identity and site of synthesis of the yolk proteins of the mosquito Aedes aegypti were studied. Disc gel electrophoresis of freshly prepared egg yolk revealed a predominant protein (YP‐1) which stained for bound lipid and carbohydrate. The molecular weight of the protein complex was estimated to be 2.7 × 10 5 . It was present in vitellogenic females and absent in males and unfed females. Yolk Protein‐1 was purified by Sepharose and DEAE column chromatography and represented 75% of the protein extractable from the egg. The lipids conjugated to YP‐1 were identified as phosphatidyl choline, phosphatidyl ethanolamine and several steroids. The carbohydrate content was estimated as 10.5% with a phenol‐sulfuric acid method, and 5.8% with an orcinol method. The site of yolk protein synthesis was determined using antibody to purified yolk to precipitate labeled yolk proteins from organ culture media. Only the fat body synthesized antibody precipitable material. Synthesis began five to six hours after the blood meal, reached a peak of activity by 20 hours and declined to low levels of synthesis by 72 hours. These data correlate well with endocrino‐logical evidence indicating that egg development requires a hormonal factor from the head from four to eight hours after the blood meal.