Metabolic Studies on Adult Nippostrongylus brasiliensis (Nematoda: Trichostrongyloidea)

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Abstract
N. brasiliensis contains 3.4% carbohydrate and 11.9% lipids (dry weight basis). Glycogen and trehalose each comprise about half the carbohydrate and both are utilized during survival in vitro. The parasites survive about 8 days aerobically and less than 24 hr anaerobically. Recovery from the effects of anaerobiosis is rapid if oxygen is excluded for less than 6 hr. Cytochrome oxidase is abundant, but flavin enzymes are not quantitatively important in electron transport as judged by the Qo2 PO2 relationship. Twice as much endogenous carbohydrate is consumed anaerobically as aerobically. Carbohydrate consumption is independent of pO2 between 8 and 158 mm, although Qo2 is not, suggesting that catabolism is primarily anaerobic. However, oxygen at a pO2 as low as 8 mm is essential for motility and the maintenance of water balance. An initial Qo2 of 7.5 declines about 33% in 4 hr and 60% in 24 hr. Exogenous glucose is not metabolized, and several lines of evidence suggest that N. brasiliensis does not feed in glucose saline. Serum stimulates Ancylostoma caninum to consume glucose in amounts judged to be physiological, but serum is a relatively ineffective feeding stimulus for N. brasiliensis, as are dialyzed preparations of intestinal mucosa and liver, and cysteine, glutathione, carbon dioxide, and sodium taurocholate. A comparison with data in the literature indicates that unlike N. brasiliensis and A. caninum, three other nematodes (Trichuris vulpis, Litomosoides carinii, and Dracunculus insignis) require no feeding stimulus other than glucose saline, and that cuticular absorption is not important.