Isotopic relationships between saponifiable lipids and cellulose nitrate prepared from red,brown and green algae

Stable carbon and hydrogen isotope ratios were determined for the saponifiable lipid fraction as well as the cellulose fraction (the latter after nitration to remove exchangeable hydrogens) of several species of red, brown and green algae from three locations. A significant correlation was observed between the hydrogen isotope ratios of cellulose nitrate and saponifiable lipid for red algae, but not for brown or green algae. Carbon-13/carbon-12 ratios for both fractions of red algae were in general lower than those observed for brown and green algae. The results reported here are consistent with the proposals that red algae evolved much earlier than and are metabolically different from the brown and green algae.Abbreviations and symbols CAM Crassulacean acid metabolism - C₃ photosynthetic mode in plants in which CO₂ is fixed into a three-carbon compound - C₄ photosynthetic mode in plants in which CO₂ is fixed into a four-carbon compound - unit used to express isotope ratios Also Archaeology Program, UCLA