Bibliothek

Notizen: Abstract We followed changes in the neutral lipid content of actively swimming zoospores of the palm kelp Pterygophora californica in a laboratory experiment to investigate the degree to which spore swimming is fueled by endogenous lipid reserves. The neutral lipid content of individual zoospores during the experiment was measured by flow cytometry using Nile Red, a fluorescent stain that is specific for neutral lipid. Results showed that photosynthesis greatly influenced lipid consumption during zoospore swimming. We found no detectable change in the neutral lipid content of zoospores after 30 h of swimming under conditions where light was near the optimum for photosynthesis. By contrast, neutral lipid declined by ≃43% over 30 h in zoospores kept in the dark. To evaluate whether lipid reserves are generally related to spore motility in macroalgae, we surveyed spore lipid-content and composition in species with motile spores and non-motile spores using thin-layer chromatography (TLC), and flame-ionization detection (FID). We observed substantial differences in lipid content and composition among the 20 species examined. Spores high in total lipid (as estimated by the ratio of lipid:carbon) generally had a large amount of neutral lipid; motile spores had significantly more lipid and a significantly larger neutral lipid fraction than non-motile spores. The kelps as a group had the highest total lipid content and the largest neutral lipid fraction, while non-motile spores of red algae were generally low in total lipid and in the proportional abundance of neutral lipid. Phospholipids accounted for more than half of all lipid in 14 of the 20 species examined, while neutral lipid accounted for the majority of lipid in all five species of kelp examined. Triacylglycerols, which function primarily in energy storage, were the primary form of neutral lipid in all but one species of kelp (Agarum fimbriatum), whereas free fatty acids were the dominant form of neutral lipid in most red algae and in brown algae that had a small neutral lipid fraction. Our results are largely consistent with the hypothesis that macroalgae use endogenous lipid reserves to fuel spore-swimming. The small amounts of triacylglycerols observed in the motile spores of several species of brown and green algae, however, indicate that the amount of lipid reserves needed to fuel spore-swimming may be influenced by a variety of factors including swimming behavior, photosynthetic efficiency, and the light environment inhabited by spores.

Notizen: Abstract Dimethylsulfide (DMS) concentrations in sea water were found to be high (0.19 to 390 nM) in an Antarctic bloom of Phaeocystis sp. during October and November 1990. DMS concentrations were positively correlated with algal pigments, particularly 19′-hexanoyloxyfucoxanthin, a prymnesiophyte pigment. Concentrations of DMS varied diurnally, possibly due to effects of sunlight, although the exact mechanism is unknown. Since oceanic DMS production has been linked to the global albedo through the formation of cloud condensation nuclei, light-mediated changes in DMS concentrations may affect the global climate. The flux of DMS from this bloom into the atmosphere is calculated to be 67±55 μmol m-2 d-1.

Notizen: Summary By gas-chromatography and mass-spectroscopy 7 volatile substances have been found on the abdominal hairpencils ofAmauris ochlea males. 6 substances have been identified. The spatial distribution of compounds is correlated to the 5 types of hairs comprising the scent organ.