Respiratory systems in the Trypanosomidae

At least two different types of hydrogen-transport system must be present in flagellates of the family Trypanosomidae (for a classification, see Hoare, 1957) since some species do not contain detectable cytochrome pigments and their respira- tion is insensitive to cyanide, azide (Brand, 1951; Ryley, 1956) and carbon monoxide (Fulton & Spooner, 1959). These differences may be observed not only among different species which infect the blood of vertebrates, but also between different forms of the same strain, whose life cycle involves both invertebrate (insect) and vertebrate stages. The present work is concemed with the nature and distribution of respiratory enzymes and enzyme systems present in subcellular fractions obtained from some of these protozoa.