Cytochromes and Respiratory Activities in Some Slow Growing Strains of Neurospora

It has been shown that the poky strain of Neurospora is deficient in some components of the cytochrome system and that respiration in this organism utilizes a different pathway for terminal oxidation (1, 2). Besides poky, three other Neurospora strains have been discovered (3) which are of considerable interest with regard to their cytochromes and their respiratory activities: (1) mi-3 which contains a high concentration of cytochrome c, rather less cytochrome b, and seems to be devoid of cytochrome a; (2) C115 with an equally high cytochrome c concentration, little cytochrome b, and hardly detectable cytochrome a; (3) C117 which, in addition to a strong cytochrome b band, shows the sharp band of cytochrome e at 552 to 553 µM but does not show any cytochrome c or a bands. The characteristics of mi-3, like those of poky, are inherited cytoplasmically, while the characteristics of C115 and C117 are inherited in a Mendelian fashion. This paper is concerned with a description of the cytochromes and the respiratory characteristics of these new strains