Hymenolepis diminuta: influence of metacestodes on synthesis and secretion of fat body protein and its ovarian sequestration in the intermediate host,Tenebrio molitor

Abstract

SUMMARY: FemaleTenebrio molitorinfected with metacestodes ofHymenolepis diminutaexhibit elevated concentrations of female-specific proteins in their haemolymph and the origin of these has been investigated. Following a 4 hin vitroincubation with [¹⁴C]leucine, fat bodies from non-infected females secreted 13 times more protein than those from females 12 days post-infection. A comparison of the uptakein vivoof radio-isotope labelled amino acids by ovaries from non-infected and infected beetles of various ages revealed no differences; however, a 51·5% decrease in protein sequestration was detected in females 12 days post-infection. Electrophoresis of homogenates of radio-isotope labelled ovaries demonstrated that the majority of label was associated with vitellin sub-units. It is suggested that the decrease in vitellogenin sequestration associated with infection results in an increase in the haemolymph concentration of these proteins despite a concomitant reduction in their secretion by fat bodies. Both fat body synthesis and ovarian sequestration are under juvenile hormone control and it is proposed that metacestodes ofH. diminutamay cause a reduction in the concentration of this hormone in the intermediate host.