Isoenzymes of snail livers. II. Dehydrogenases

Metabolic end-products in parasitic helminths and their intermediate hosts

Oxidoreductases which control the metabolic end-products in helminth parasites and their intermediate hosts were reviewed, in a trial to elucidate the respiratory metabolism during host-parasite associations. Special attention was given to Schistosoma parasites and their molluscan hosts.

Genetic variation among laboratory strains of the planorbid snail Biomphalaria glabrata

Isozymes of laboratory strains of Biomphalaria glabrata have been studied by starch gel electrophoresis. Methods are outlined for adaptation of this technique to the genetic study of these snails. Twenty-eight presumptive gene loci have been identified. Twelve invariant enzymes were observed. Sixteen loci displayed some polymorphism within or among the strains. These polymorphisms were generally widespread among strains from Brazil, Puerto Rico, St. Lucia, and the Dominican Republic. A high degree of intrastrain polymorphism was noted even in some presumably inbred laboratory strains. Crosses between strains were used to demonstrate the genetic basis for the patterns observed at 9 of the 16 polymorphic loci.

Lactic acid formation in crustaceans and the liver function of the midgut gland questioned

1. The possibility of the midgut gland of the crustacean (Cherax destructor) functioning as a liver has been investigated. 2. Seven species of crustaceans accumulate lactic acid in the haemolymph when exercised. The rate of disappearance of lactate in Homarus gammarus and in C. destructor is very slow when compared with man. 3. In the midgut gland of C. destructor no firm evidence was obtained for gluconeogenesis from lactate and for ketogenesis from fatty acids. 4. It is concluded that there is at present no justification for the common practice of calling the midgut gland an hepatopancreas.

Enzyme electrophoresis and speciation of Schistosoma intermediate hosts

1. Enzyme electrophoretic patterns from populations of snails, intermediate hosts of Schistosoma, have been examined.

2. Esterase patterns (α-naphthyl butyrate as substrate) have been used to differentiate snail populations of B. africanus and Biomph. pfeifferi.

3. Malate, β-hydroxybutyrate and α-glycerophosphate dehydrogenases may be of use in some cases to distinguish between species, e.g. B. africanus v. B. ugandae and Biomph. sudanica v. Biomph. pfeifferi.