Glycogen metabolism in Schistosoma mansoni worms after their isolation from the host

Abstract

Adult Schistosoma mamoni worms rapidly degrade their endogenous glycogen stores immediately after isolation from the host. In NCTC 109 or in a diphasic culture medium the glycogen levels slowly recovered again after the initial decrease. The rapid degradation of glycogen could be prevented, even in a simple salt medium, if 100 mM glucose and 1% bovine serum albumin were present. Incubations with t4C-labelled glucose under different conditions revealed that the degradation of glycogen was induced by the limited catabolism of external glucose. Conditions are described which induce glycogen degradation or resynthesis by S. manson/. The physiological function of the glycogen stores is probably to provide substrate during periods of insufficient supply of external glucose. It is speculated that such periods occur when the worm pair moves into the small mesenteric veins of the host. This hypothesis explains the remarkable wandering behaviour of the parasite in the mesenteric veins, since the schistosomes would have to return to larger vessels when their endogenous glycogen stores are exhausted.

Schistosoma mansoni does not and cannot oxidise fatty acids, but these are used for biosynthetic purposes instead

“…Adult S. mansoni worms were isolated from isoflurane anaesthetized hamsters seven weeks after infection. Worms were collected from the portal vein following heart perfusion with S 20 medium (20 mM HEPES, 85 mM NaCI, 5.4 mM KCI, 0.7 mM Na 2 HPO 4 , 1 mM MgSO 4 , 1.5 mM CaCI 2 , 25 mM NaHCO 3 and 20 mM glucose pH 7.4) (Tielens and van den Bergh, 1987)]. S. mansoni eggs were obtained from livers of infected hamsters.…”