Effect of Xiphidiocercarial Infection on the Activities of Glycolytic and Oxidative Enzymes in Lymnaea luteola

Abstract

The activities of aldolase, malate dehydrogenase, cytochrome oxidase, and NADH oxidase were studied in the foot, mantle, and digestive gland of the freshwater gastropod, Lymnaea luteola, infected with xiphidiocercaria of Prosthogonimus sp. The aldolase:MDH ratio was reduced in all three tissues of infected snails. The overall decrease of NADH oxidase in all the infected tissues and the significant reduction of cytochrome oxidase activity in the infected digestive gland might lead to the accumulation of NADH. It was concluded that the TCA cycle probably was activated in order to supply organic acids that can be utilized either by the host or by the parasite. Marshall et al. (1974) demonstrated in- creased levels of several glycolytic enzymes in the parasitized digestive gland of the proso- branch Littorina saxatilis, and Mengebier and Wood (1967, 1969) reported reduced ac- tivities of glycolytic and oxidative enzymes in infected Crassostrea virginica. Though Mc- Manus and James (1975a, b) studied the in- termediary metabolism of the gastropod host, Littorina saxatilis, separate from parasites, their main concern was to compare the en- zyme systems and metabolic pathways be- tween the digestive gland of the host and the daughter sporocysts of Microphallus similis. They showed that the distribution of the Krebs cycle enzymes was similar both in the host digestive gland and the daughter sporo- cysts. Studies on Lymnaea luteola revealed that the adenylate pool size and the oxidation of substrates were altered in infected Lymnaea luteola (Narayanan and Venkateswara Rao, 1978a, b). Therefore, study of changes in the activity profiles of the enzymes catalyzing im- portant metabolic steps seems warranted. Such changes in Lymnaea luteola infected