| Abstract: | We have examined the influence of temperature, protein synthesis, and energy metabolism on the process of silicon biomineralization in synchronized cultures of the diatom Navicula saprophilia Lange-Bertalot & Bonik (1976). Temperature effects on silicon polymerization were compared in vitro and in vivo. In vivo incorporation was very temperature dependent with a Q10 of 7.53. In contrast, the Q10 for in vitro polymerization was 1.42, indicating much lower temperature dependence. This difference in Q10 values suggests that in vivo polymerization involves more than autopolycondensation. Cycloheximide addition to synchronized cultures up to, but not later than one hour after the addition of silicic acid depressed total uptake, incorporation, but not pool size. Developing valves demonstrated morphological abnormalities with cycloheximide additions from 0 to 2 h following silicic acid addition. These data suggest that de nova proteins are required in biomineralization and that they are synthesized during or just after cytokinesis. Biomineralization is not coupled to energy derived directly from photosystem II or photosynthesis, since neither darkness nor DCMU had an effect on any aspect of silicification. |
