Institution: | Department of Biology, Faculty of Science, Osaka University, Toyonaka, Osaka 560, Japan |
Abstract: | 1. The spermatozoa of the freshwater mussel (Hyriopsis schlegelii) contain cytochromes aa3, b and c, flavoproteins and nicotinamide nucleotides in molar ratios of 1.0:0.9:1.8:1.8:8.7. Cytochrome c1 is not detectable even at liquid-N2 temperature, but a c1-like cytochrome with an -band at 550 mμ is found at liquid-N2 temperature in a cell preparation from which cytochrome c is completely removed. 2. The near-ultraviolet difference spectrum of whole cells reveals an absorption peak at 315 mμ with a shoulder around 350 mμ. 3. Both the endogenous respiration and motility of spermatozoa are completely blocked by 0.2 mM CN? and by 0.2 μM antimycin A. 2,4-Dinitrophenol and pentachlorophenol completely inhibit motility at the maximal stimulation of respiration. Rotenone strongly inhibits NADH oxidase of spermatozoa, although it has no effect on the respiration of whole cells. 4. It is concluded that the motility of mussel spermatozoa is tightly coupled to respiration, and the respiratory chain phosphorylating process is the only energy-supplying system for motility. |