Mitochondria in Allomyces under experimental conditions

Abstract

1. 1. The vegetative hyphae of aquatic fungi are described as favorable material for the study of mitochondria in the living state, particularly when observed with phase contrast optics. 2. 2. Immobilization of mitochondria without morphological change was realized by treatment of hyphal cells with 1 per cent solution of OsO 4. 3. 3. When hyphae were mounted in isotonic NaCl, the mitochondria, being as sensitive to mechanical shock as they were when the hyphae were in water, disintegrated under pressure. In hypertonic saline, cells were at first plasmolysed, but recovered. Mitochondria in plasmolysed cells changed shape, fragmented, became vesiculated, and disappeared after becoming pale and non-refractive. 4. 4. In cells treated with 0.88 M sucrose, which has been useful in isolating mitochondrial particles from animal tissues, the fungal mitochondria quickly fragmented into spheres about 1 micron in diameter. 5. 5. A solution of 10 −2 M KCN in 10 −2 M glutamic acid, at pH 7.0, caused cessation of movement of mitochondria and inhibited staining by Janus green B. No evidence of mitochondrial damage was apparent. 6. 6. Temperatures of 8 °–45 ° C. had no visible effect on mitochondria. At higher temperatures, the results were as follows: 50 ° C., mitochondria became slender, and almost invisible; at 65 ° C., all mitochondrial motion ceased; at 75 ° C., mitochondria broke up into beads which became hollow spheres and disappeared. 7. 7. Mitochondrial orientation is determined more by the direction of protoplasmic streaming than by direction of diffusion. 8. 8. Small granules, never positively identified as normal mitochondria, were “stained” red after 48 hours with triphenyl tetrazolium chloride when the salt was incorporated in the medium at a concentration of 0.005 per cent. Higher concentrations were lethal. The sites at which reduction of the tetrazolium was most active were in the fat droplets. 9. 9. Because of the diversity of behavior and function of the particles referred to as mitochondria, it is suggested that many cytoplasmic particles, even though they do accumulate Janus green, are scarcely comparable to one another.