Studies on the Biochemistry and Fine Structure of Silica Shell Formation in Diatoms. Photosynthesis and Respiration in Silicon-Starvation Synchrony of Navicula pelliculosa

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Abstract
Rates of photosynthesis, measured by oxygen electrode or by 14CO2 fixation, dark respiration and 32p-phosphate incorporation are reported for the silicon-starvation synthrony of the fresh water diatom N. pelliculosa. During late exponential growth the rates were consistent with increase in carbon mass. During silicon starvation, rates of CO2 fixation, O2 evolution and 32p incorporation fell, and the saturating light intensity decreased from 27,000 lux to 5000 lux. Reintroduction of silicon led to immediate transients in all parameters studied, followed by a prolonged increase in rate of dark respiration and a gradual increase in apparent photosynthesis. During release of daughter cells, the rates of dark respiration decreased as photosynthesis and 32p incorporation increased. These results are discussed in relation to effects of silicon on the energy metabolism of the diatom.