Role of fat body and uterine gland in milk synthesis by adult female Glossina morsitans

Abstract

Using [U- 14C] leucine or [U- 14C] palmitate as substrate, the ability of fat body and uterine gland of Glossina morsitans morsitans to synthesize lipids and proteins has been studied using in vivo and in vitro techniques. During early pregnancy, the fat body synthesizes triglyceride but this ability diminishes before the larva hatches and is followed by a massive transfer of triglyceride from fat body to uterine gland at the time of most rapid larval growth. Results support the hypothesis that a major proportion of the lipid component of larval milk is synthesized during early pregnancy, whereas the bulk of the protein component is supplied more directly from the products of digestion of blood meals ingested later in pregnancy. The fat body comprises a mosaic of cells, whose overall synthetic ability is determined both by variations in the activity of individual cells and by the number of cells which are active at any one time. The implications of these findings in terms of a humoral regulation of nutrient synthesis for larval growth in G. morsitans are discussed.