[Quantitative investigations on vitellogenic protein metabolism in the honey bee (Apis mellifica)]

The soluble proteins of the haemolymph, ovary and eggs of the honey bee were separated by electrophoresis on cellulose acetate foils and on polyacrylamide gels. The predominant haemolymph fraction (60-80%) is a female-specific protein. Corresponding fractions are found in the ovary and in uncleaved eggs. According to the results, it is highly probable that these fractions represent the yolk material or vitellogenin. InApis, this vitellogenin is represented by only one protein band which carries no carbohydrate components.The haemolymph titre of vitellogenic protein depends on the physiological state of the female bees. In the worker bees, haemolymph yolk proteins are detectable only during the nurse age, whereas in queens they can be found throughout the year. It may be noted that in the mated and egg producing queens the concentration of vitellogenin in the haemolymph is lower than in virgin queens and in adult non-laying queens.The rate ofin vivo protein synthesis was determined by injecting a mixture of¹⁴C-amino acids and measuring the radioactivity in pherogram bands using a methane flow counter. In the actively laying queen the rate of vitellogenin synthesis is 3 times higher than that of the non-sex-specific blood proteins. Approximately 85% of the labeled proteins which are released from the fat body are yolk material. In contrast to other insects, non-laying queens were also found to synthesize vitellogenin; however, the rate did not exceed that of the other serum proteins. The fate of yolk material in such females is unknown. In the ovary, synthesis of the euplasmic proteins occurs at a rate similar to that of the nonspecific haemolyph fractions. The appearance of radioactivity in the ovarian yolk is delayed compared with all other proteins. This indicates that these proteins are labeled byde novo synthesis, whereas the yolk is not built up within the ovary. This conclusion is further supported by the fact that the increase in specific radioactivity of ovarian yolk proteins occurs at a time when free¹⁴C-amino acids are no longer available in the haemolymph. Following the maximum intensity of labelling of yolk proteins the specific activity declines. From the data it can be estimated that the period of vitellogenesis for a single follicle is 2 days; 2 additional days of maturation, during which glycogen synthesis and chorion formation occur, are required before oviposition.