Carbohydrate Metabolism of Schistosoma Mansoni

Abstract

In contrast to vertebrates and to bacteria relatively little is known about the metabolism of invertebrates (1). For a better understanding of comparative biochemistry information about this subject is required. Furthermore, investigations of the biochemical characteristics of parasitic invertebrates will reveal metabolic reactions essential for survival of these organisms. Information obtained from such studies will make it possible to search for non-toxic inhibitors of essential metabolic reactions and eventually may afford a possibility of replacing the presently prevailing empirical methods with a more rational development of chemotherapeutic agents against pathogenic parasites. ~c c o r d i n g l y , when an investigation concerned with the chemotherapy of schistosomiasis was initiated in this laboratory, it was decided to study the metabolism of Schistosoma mansoni, an organism concerned with the pathogenesis of one form of this disease. Materials and MethodsThe schistosomes were removed with the aid of dissecting needles from the mesenteric and portal veins of mice infested with Schistosoma mansoni. The infestation had been produced by the intraperitoneal injection of 125 to 150 cercariae per mouse 6 to 10 weeks previously. The cercariae were obtained from shedding snails (Australorbis glabratus). The latter were either naturally infested snarls collected in Puerto Rico or they had been infested by exposure to miracidia from eggs present in the livers of mice with sehistosomiasis.~ The sehistosomes were placed in a medium of the following composition: 0.137 r~ NaC1, 0.0085 ~ KC1, 0.0003 ~r CaCI~, 0.005 ~ MgCI~, and 0.06 sodium phosphate or glycylglycine buffer. The pH of this solution was 7.7. After several washings with this medium, 10 to 25 pairs of worms were transferred into 0.8 ml. of medium contained in a Warburg respirometer vessel (total volume of vessel: 4 to 5 ml.). Incubation was carried out at 37.5°C. for a period of 2 hours. After several * The major part of the investigation described in this paper was carried out with the aid of a

Profiling Schistosoma mansoni development using serial analysis of gene expression (SAGE)

“…However, role of oxygen in adult metabolism is less well defined. While it has been reported that no increase in lactate production is seen in worms incubated under anaerobic conditions (Bueding, 1950), other studies indicate that oxygen may be essential, especially if worms are to maintain high egg production levels, and that adult worms possess a functional tricarboxcylic acid cycle and respiratory chain (Coles, 1972). Profiling SAGE tags for the tricarboxcylic acid enzyme, succinate dehydrogenase, and the terminal oxidase beta subunit clearly indicate that the expression of genes encoding enzymes of oxidative respiration is equal or higher in mammalian-stage parasites than in snail-stage parasites (Fig.…”

Biochemical and histological changes in liver ofNectomys squamipes naturally infected bySchistosoma mansoni

“…In enzymatic studies, Bueding (1950) found that schistosome survival and reproduction depend directly on the absorption and utilization of the vertebrate host's carbohydrates as a of source energy, in a quantity of glucose equal to 20% of their weight per hour. The parasite metabolizes glucose by the Embden-Meyerhoff pathway, mainly under anaerobic conditions BUEDING, 1953BUEDING, , 1954BUEDING;MacKINNON, 1955).…”

Sm14 gene expression in different stages of the Schistosoma mansoni life cycle and immunolocalization of the Sm14 protein within the adult worm

“…Heart FABP is expressed at high levels in the myocardium, associated with ß-oxidation to generate power to the muscle (17). Although Sm14 has a higher phylogenetic relationship to heart FABP, it is known that S. mansoni is unable to use lipids as a power source (18,19).…”