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Haemonchus histochemistry, biochemistry and immunology7Various elements detected in H. contortus (Sood and of glycogen utilization is similar both in male andKapur, 1980) include phosphorous (P), zinc (Zn), female (Premvati and Chopra, 1979). Under in vitrocalcium (Ca), iron (Fe), magnesium (Mg), copper conditions, the worms readily utilize glucose from the(Cu), manganese (Mn), boron (B) and potassium (K), medium (Chopra and Premvati, 1977; Kaur and Sood,in decreasing concentrations in female. In the male 1982a). At the same time, glucose is excreted and thisalso, same elements are present, with the exception of excretion is possibly at the expense of endogenousB. The relative order of occurrence in the male is glycogen reserves, which falls rapidly with time. AnP>Ca>Zn>Fe>Mn>Mg>Cu>K. Presence of more Ca, outstanding feature of carbohydrate catabolism inP and Fe in male has been discussed.nematodes is the production of reduced organic endCarbohydratesproducts, even under aerobic conditions.The in vitro effects of TMS and RFX on theseCarbohydrates form the chief energy source inconstituents have also been studied (Kaur and Sood,parasitic nematodes. In view of the importance of1982a).carbohydrates in helminths, any difference in theircarbohydrate metabolism and that of their hosts might The pathway of carbohydrate breakdown in H.be usefully exploited in helminth control. The contortus has been worked out as follows:outstanding feature of carbohydrate breakdown innematodes is the production of reduced organic end Glycolysis: Adult worm utilizes glucose bothproducts and this occurs even under aerobic aerobically and anaerobically. Under both aerobic andconditions.anaerobic conditions, end products of glucosemetabolism include CO 2, propanol, acetate, and n-Carbohydrate metabolism in H. contortus has beenpropionate as the major and ethonol, lactate andreviewed (Kaur and Sood, 1983b) under the titles :succinate as the minor components. It is unique amongglucose and glycogen utilization, carbohydratenematodes that propanol is a major excretory product.metabolism, including the glycolytic pathway, theThis is possibly produced by reduction of propionatepathway of CO 2 fixation, the TCA cycle and theand hence glucose catabolism in H. contortus does notpentose phosphate pathway.indicate a major departure from the known pathwaysGlucose and glycogen utilization: Glucose in very of anaerobic glucose utilization. Production of lactateimportant energy source for many helminths from glucose in H. contortus has been demonstratedinhabiting the gut of vertebrates. It is generally by Chopra and Premvati (1977). In female 90-100% ofbelieved that helminths absorb glucose against a glucose and in male 80-90% is catabolized to lactate.concentration gradient and use their endogenous Both glucose consumption and lactate productioncarbohydrates as an energy source only when it is decrease with the progression of incubation.unobtainable from outside. Similarly, glycogen inmost of the nematodes provides a significant reserveEnzymes of glycolysis have been detected in adult H.store of energy, particularly in forms which arecontortus (Kaur and Sood, 1982b). These includeparasitic in animals and which exist in environmentshexokinase, phosphoglucomutase, phospho-of low oxygen tension.glucoisomerase, aldolase, glycerladehyde-3-phosphate dehydrogenase, phosphoglycerate kinase,Amount of glucose and glycogen contents in H. phosphoglyceromutase-enolase-pyruvate kinase,contortus has been determined. It contains pyruvate kinase (PK), and lactate dehydrogenaseconsiderable amount(8-12% fresh tissue of glycogen; (LDH). Low PK and LDH activities suggested anChopra and Premvati, 1977; Premvati and Chopra, alternate pathway from phosphoenolpyruvate. LDH1979; Kaur and Sood, 1982a). Famale has more exhibits optimum activity (about 180 nmoles/min/mgglycogen than male (Premvati and Chopra, 1979). protein at a pH of 6.6 and a temperature of 37° CThis is possibly related to the reproductive role of (Kapur et al., 1985). Thermostability of LDH has alsofemale rather than with general metabolism. Adult been studied (Harpreet et al., 1991).worm utilizes glycogen reserves rapidly. In male, itdecreases less rapidly with time, while lin female, itVarying degrees of inhibition of glycolytic enzymesdecreases exponentially with time. Thus, in female, have been observed with 50 µg/ml of TMS and RFXrate of glycogen utilization at any time is directly treatments, former being more effective. These effectsproportional to glycogen content. However, initial rate may block the glycolytic pathway and deprive the