Histochemical localization of key glycolytic and related enzymes in adultOnchocerca fasciata

Abstract

The activities of some key enzymes of the glycolytic and pentose phosphate pathways were investigated histochemically in adult female Onchocerca fasciata (Nematoda: Filarioidea). The distribution patterns of phosphofructokinase (PFK), aldolase (ALD), glyceraldehyde 3-phosphate dehydrogenase (G3PDH) and glucose 6-phosphate dehydrogenase (G6PDH) in different tissues of the worm were determined by employing NitroBlue Tetrazolium (NBT). The glycolytic enzymes PFK, ALD, and G3PDH were distributed throughout the hypodermal tissue, somatic muscles and reproductive organs. These enzyme activities were predominantly expressed in the hypodermal and reproductive tissues, both of which appeared to be metabolically more active than adjacent tissues. The high activities of the enzymes studied in the hypodermal tissue when compared with the minimal or low activity in the intestinal epithelium support the assumption that the worm's intestine, in contrast to the body wall, plays no significant role in the nutrient acquisition process. The results emphasize that both the glycolytic and hexose monophosphate pathways of carbohydrate metabolism are active components in energy production and biosynthetic processes in the various tissues of the worm. The functional significance of these glucose-metabolizing enzymes has been discussed with regard to their location in the tissues concerned.

Onchocerca fasciata: Enzyme histochemistry and tissue distribution of various dehydrogenases in the adult female worm

“…(See Barrett 1983 for review). The present and recent histochemistry studies on O. fasciata (Omar and Raoof 1994b) have shown that specific glycolytic and related enzymes are present in different tissues and organs of the worm. In filariae, as in other parasitic helminths, glucose metabolism proceeds via glycolysis as far as the level of phosphoenolpyruvate (PEP; Saz 1981;Barrett 1983;Tielens and Van den Bergh 1985).…”

“…The presence of significant amounts of G-PGDH activity may be taken as an indication of a pentose pathway in adult O. fasciata, especially as the starting enzyme of this pathway, G-6-PDH, has been demonstrated in this filarial worm (Omar and Raoof 1994b). The first two enyzmes of the cycle (G-6-PDH and 6-PGDH), have been characterized biochemically in other filarial worms (Barrett 1983), although their presence does not necessarily mean that the cycle is complete (Barrett 1981).…”

Expression of key substrate cycle enzymes in rat spermatogenic cells: Fructose 1,6 bisphosphatase and 6 phosphofructose 1‐kinase

“…The cells were then spread on a clean glass slide and dried using a stream of warm air. A silicone grease mixture was used to delimit the area where 200 µl of the reaction mixture, containing twice the enzyme concentrations described above and 1.2 mM 2,2 di‐p‐nitrophenyl‐5,5,‐diphenyl‐3,3‐(3,3‐dmethoxy‐4,4‐diphenylene)‐ditetrazolium chloride (NBT) in addition to the components described in the previous section, were added (e.g., Omar and Raoof, 1994). The reaction was started with 1 mM Fru‐1,6‐P 2 .…”