Benjamin Elazari Volcani

Scientific career In 1939, Volcani became a member of the Sieff Institute in Rehovot, later renamed the Weizmann Institute of Science. He headed its laboratory of microbiology until 1959, when he joined the faculty at Scripps Institution of Oceanography. He decided to focus on diatoms, one of the very few organisms that use silicon rather than calcium for their skeletal structures. Silicon is one of the most abundant elements on earth, and in 1959 no one was working on its metabolism. The biology of silicon had been shunned by all biochemists, the dogma being that it was inert. Volcani realized that diatoms, whose life cycle is based on silicon, provided an ideal experimental canvas. From 1959 onward, his lab made multifaceted discoveries centered on biologically active silicon in marine diatoms. The lab became a focal point for the study of silicon metabolism and biomineralization at the molecular level, embracing experimental techniques, from elegant electron microscopy of diatom shells to gene cloning and the expression of silicon transporting proteins in frog eggs.

He invented ways to synchronize the cell division cycle of diatoms. He showed that silicon activates the gene coding for the polymerase enzyme that copies diatom DNA. He was also interested in the toxic and pathological effects of polysilicates, such as talc and asbestos, on mammalian cells in tissue culture, and was the first to do tissue culture at Scripps. He spent a one-year sabbatical at the University of Swansea studying the effects of polysilicates on mammalian cells, and published papers on the uptake of silicic acid by rat liver mitochondria.

His studies of silicon metabolism often involved growing diatoms of various species in different concentrations of silicon and then studying the effect on specific metabolic pathways. These experiments studied pigments, lipids, amino acids, cell wall synthesis, DNA synthesis, ribosomes, sodium-potassium membrane pumps, cell membrane characterization, glycolate metabolism, cyclic nucleotide metabolism, protein kinases, and a catalog of genes that were turned on by silicon. Several papers centered on the effects of silicon on photorespiration in diatoms.

He published over 100 papers related to silicon metabolism and co-edited Silicon and Siliceous Structures in Biological Systems (Springer, 1981). He received continuing grants from the National Institutes of Health for 32 years. He trained many doctoral students and had a constant stream of postdoctoral associates and visitors passing through the lab until his retirement in 1985.