Schistocephalus

Brophy, P.M., Papadopoulos, A., Touraki, M., Coles, B., Korting, W. and Barrett, J. (1989) Purification of cytosolic glutathione transferases from Schistocephalus solidus (plerocercoid) interaction with anthelmintics and products of lipid peroxidation. Molecular and Biochemical Parasitology 35, 1 87-1 95. 

Microstomum lineare Polycelis nigra Diphyllobothrium dendriticum Schistocephalus solidus... 

Many cestodes appear to behave like osmometers, and when placed in an environment with a different osmotic pressure can only adjust their internal osmotic pressure by varying their body volume. Moniezia, Hymenolepis, Schistocephalus and Callibothrium change their weight almost arithmetically in response to a change in external osmotic pressure (796). 

The major phosphagens found in nature are arginine and creatine but parasitic helminths are unusual in that they possess no detectable phosphagens and none occurs in Hymenolepis diminuta, Moniezia expansa, Ligula intestinalis or Schistocephalus solidus (44). This absence of phosphagens has implications for control of metabolism in cestodes. If... 

Hymenolepis diminuta (adult) Schistocephalus solidus (plerocercoid) Ligula intestinalis (plerocercoid)... 

Some useful, general studies on intermediary metabolism include those on Monieziaexpansa (59-61,664) H. diminuta (400,531,590,612,667) H. microstoma (665, 666) Echinococcus spp. (488, 498, 500) Mesocestoides corti (399) Cotugnia digonopora (618, 619) Schistocephalus solidus (406) and Ligula intestinalis (502). 

Schistocephalus solidus Acetate, propionate of propionate, succinate Propionate, acetate... 

Enzyme Apparent equilibrium constant granulosus0 (protoscoleces, ovine strain) Echinococcus multiloculari (protoscoleces) Moniezia expanseJ (adults) Hymenolepis microstomac (adults) Schistocephalus solidus 1 (plerocercoids) Ligula intestinalif (plerocercoids)... 

This enzyme catalyses the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate (FBP) and is the key regulatory enzyme of glycolysis. The properties of phosphofructokinase (PFK) have been investigated in some detail in adult Moniezia expansa (60) and in plerocercoids of S. solidus (65), where its activity is modulated by a number of compounds, including ATP, AMP, fructose-6-phos-phate, Mg2 +, Mn2 +, K + and NH. In general, the PFKs from both species exhibit properties similar to those of the enzymes from mammalian sources and they probably regulate glycolysis in the same manner as their mammalian counterparts. The inhibitory effects of ATP on the PFK from Schistocephalus solidus and the relief of this inhibition by AMP are shown in Fig. 5.2. 

Fig. 5.2. Plot of the activity of phosphofructokinase from plerocercoids of S. solidus against the concentration of ATP in the presence and absence of 2 mM AMP. The concentration of fructose 6-phosphate was 1 mM. (Reprinted with permission from International Journal for Parasitology, 12, Beis, I. Theophilidis, G. Phosphofructokinase in the plerocercoids of Schistocephalus solidus (Cestoda Pseudophyllidea), 1982 Pergamon Journals Ltd.)...

It has been purified (445) and shares some properties in common with malic enzymes from mammals and birds in being NADP-dependent, heat-stable and able to decarboxylate oxaloacetate. The malic enzyme of H. microstoma also has a marked specificity for NADP (216), contrasting with that of Spirometra mansonoides, which appears to be both NAD- and NADP-linked (220). Malic enzyme has been demonstrated in a range of other cestodes including Mesocestoides corti (399), Schistocephalus solidus (406), Moniezia expansa (60), Echinococcus spp. (500) and L. intestinalis (502). 

In general it is difficult to assess experimentally the importance of the TCA cycle to the energy budget of cestodes, since, as we have seen, partly oxidised metabolites are excreted as end-products even under aerobic conditions. Notwithstanding, there is increasing evidence that, under aerobic conditions, certain cestodes such as Schistocephalus solidus (406) and Echinococcus spp. (500) are capable of catabolising substantial... 

Proteolytic activity has also been detected in Schistocephalus solidus (777), Ligula intestinalis (514, 515,516), Taenia saginata (287, 288), Moniezia expansa (182) and E. granulosus (491). 

In Schistocephalus, worms cultured free in liquid media fail to inseminate and the cirrus can often be observed projecting from the genital pore and the... 

Fig. 8.4. Seasonal prevalence of procercoids of Schistocephalus pungitii and Proteocephaius filicollis in copepods in Lake Koljushkovoe, USSR. (After Sysoev, 1985.)...

Early work has been reviewed in the first edition relevant recent references include Diphyllobothrium dendriticum, D. latum and Diphyllobothrium spp. (172, 421) Ligula intestinalis (269, 421) Schistocephalus solidus (255, 269), Triaenophorus nodulosus(269) T. crassus(269, 712, 713) Spirometramansonoides(64I) S. erinacei (269,330,424-426,972) Eubothrium spp. (269) Haplobothriumglobuliforme (484) Penetrocephalus sp. (119). 

Schistocephalus solidus has its plerocercoid stage in an ectotherm (the fish Gasterosteus aculeatus) and its adult stage in an endoderm (a fish-eating bird) and it serves as an excellent model for the study of temperature adaptation in parasites. Walker Barrett (922,923) have studied the effect of temperature on (a) the activities of the mitochondrial enzyme adenosine triphosphatase (ATPase) and (b) the physical state of mitochondrial membranes in adult and larval S. solidus. 

Fig. 8.15. Monthly variation in the ovarian content of the three-spined stickleback, Gasterosteus aculeatus, parasitised with the progenetic plerocercoids of Schistocephalus solidus. (After Meakins, 1974.)...

The dominating feature in the process of establishment is the morphology of the scolex. In the Pseudophyllidea, this can vary from a structure that is little more than a shallow groove - as in Schistocephalus or Ligula - to a well-developed bothrium, as in Diphyllobothrium spp., which, when... 

Establishment is greatly facilitated in these two species by the fact that the plerocercoids are progene tic (p. 211) and rapidly reach maturity after only 48 h (Schistocephalus) or 72 h (Ligula) in their bird hosts - a process which has been successfully completed in vitro (Chapter 10). 

Fig. 9.2. Position of the pseudophyllideancestode, Schistocephalus solidus when established in different laboratory hosts. (After McCaig Hopkins, 1963.)...

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