Effects of Boron Deficiency on Rubidium Uptake and Photosynthesis in the Diatom Cylindrotheca fusiformis.

Culturing the diatom Cylindrotheca fusiformis under boron-deficient conditions leads to changes in (86)Rb uptake and photosynthesis prior to any effect on the rate of cell division. The influx rate of (86)Rb into boron-deficient cells was 79% of the control rate after 5 to 5.5 hours culture. Despite lowered (86)Rb influx, however, boron-deficient diatoms accumulated more (86)Rb than did control cells; this was due to the deficient cells' lower efflux rate. After 24 hours culture, boron-deficient cells had accumulated 30% more (86)Rb than had control cells, while releasing (86)Rb at only one-half the control rate. Increased photosynthetic rates were another effect of boron deficiency during this early stage of culture. Prior to 20 hours boron-deficient culture, diatoms had photosynthetic rates 37% greater than those of control cells. Corresponding to the increase in photosynthesis, boron-deficient diatoms had 12% more carbohydrate than control cells after 16 hours culture.