The relationship between nutrition, haemolymph proteins, and ovarian development in Musca domestica L.

Abstract

Eleven discrete protein fractions were detected in the haemolymph of newly emerged houseflies by electrophoresis on polyacrylamide gels. Milk-fed females undergoing ovarian maturation showed pronounced increases in fraction 4. Carbohydrate-fed females showed no increase in fraction 4 and no ovarian development. Milk- and carbohydrate-fed males showed little and no increase in this fraction. Total haemolymph protein increased in milk-fed females, increased slightly in milk-fed males, and decreased in carbohydrate-fed males and females. Extracts of mature eggs contained many protein fractions with electrophoretic mobilities identical to haemolymph fractions. Their possible derivation from the haemolymph is discussed. Fraction 4 was not detected in egg extracts. Although haemolymph electropherograms of newly emerged males or females were essentially similar, large quantitative differences not related to the ovarian cycle occurred under identical dietary conditions. Fractions 9, 10, and 11 changed little in milk-fed females, but became the predominant fractions in milk-fed males. The disappearance of fraction 3 as the major haemolymph component on emergence (35·8 per cent of photoelectric scans) to a minor fraction (7·7 per cent of photoelectric scans on day 4) was common to males and females fed carbohydrate or milk. Microanalytical procedures described in this paper combined with the controlled dietary conditions of the experimental animal have proved to be a useful approach for the study of the function of insect haemolymph proteins. It is suggested that an adequate adult protein diet, essential for the development of house fly ovaries, may operate principally by elevating the total protein content or the content of one or more specific protein fractions in the haemolymph to a level which will initiate (directly or indirectly) and sustain ovarian development.