bUnequivocal class separations of tissue lipids are important particularly whcn high temperature gas Chromatography is used at the same time for the determination of the long-chain acid composition of major lipid classes. This problem was studied most recently by Hirsch and Ahrens (1) ; their procedurc involves silicic acid column chromatography with clution by ether-petroleum ether mixtures fo...

Subantarctic Southern Ocean surface waters in the austral summer and autumn are characterized byhigh concentrations of nitrate and phosphate but low concentrations of dissolved iron (Fe,-0.05 nM) and silicic acid (Si, <1 gM). During the Subantarctic Zone AU9706 cruise in March 1998 we investigated the relative importance of Fe and Si in controlling phytoplankton growth and species composition a...

It is now well established that the various lipide classes of blood (1)) liver (2)) and other organs are metabolically dissimilar. The different fatty acids of the diet (3) and within the organism (4) also have been shown to have variable functions and effects. Methods have recently become available for the rapid and precise analysis of these fatty acids (5) and it is reasonable to expect that ...

Biosilicification in diatoms is achieved by specific interactions between silaffins, composed of polypeptides and long-chain polyamines, and silicic acid derivatives. The polycondensation of silicic acids is reported to be catalyzed by the long-chain polyamines that mainly contain tertiary N-methylpropyleneimine moieties. In this report, we utilized a tertiary amine-containing polymer, poly(2-(...

THE presence of silica in blood, and the much larger amounts sometimes found in urine, indicate that silica is appreciably soluble in body fluids. The determination of such solubility, however, is a matter of considerable difficulty and different results have been obtained by various workers, owing to the operation of such variable factors as particle size, concentration of suspension, method o...

Plants take up silicon as mono-silicic acid, which is released to soil by the weathering of silicate minerals. Silicic acid can be taken up by plant roots passively or actively, and later it is deposited in its polymerized form as amorphous hydrated silica. Major silica depositions in grasses occur in root endodermis, leaf epidermal cells, and outer epidermal cells of inflorescence bracts. Deba...