A novel phospholipid containing arsenic was formed by all marine algae culture in [74Aslarsenate. Compo-nents of the labeled algal extracts readily separated by twodimensional paper radiochromatography. Base-catalyzed deacylation of the major lipid yielded a phosphodiester identical to one of the two major water-soluble compounds. Acid or enzymic hydrolysis of the phosphodiester produced a product identified as trimethylarsoniumlactic acid. The structure of the phospholipid therefore is O-phosphatidyltrimethylarsoniumlactic acid. Detoxication of arsenate by marine algae leads to accumulation of the arsoniumphospholipid as a major reservoir for arsenic. Its degradation to trimethylarsoniumbetaine, dimethylarsinic acid, methanearsonic acid, and arsenate in marine food chains and its metabolism in human beings are of considerable interest. Oceanic phosphate levels, reduced at the surface by phytoplankton and bacterial consumption, approach those of arsenate. In tropical waters, and especially the Sargasso Sea, arsenate concentrations even exceed those of phosphate (1, 2). Both ions are absorbed by their common transport system. Marine algae have developed effective procedures for detoxicating arsenate which, if it were allowed to accumulate to 1 ;4M, could cause serious uncoupling of phosphorylation. Bacteria (3), corals (4), and algae (5) reduce arsenate to arsenite which, similarly, would inhibit sulfhydryl enzymes of glycolysis at 1 mM unless it were further metabolized. Recognition of very low concentrations of methanearsonic acid and of dimethylarsinic acid (cacodylic acid) and their measurement by Andreae (6) Chromatography. Concentrated cell extracts were chromatographed two dimensionally on Whatman no. 4 paper and radioautograms were prepared (9). The orange dye, Tropaeolin 000, was an invaluable chromatographic reference.Paper Electrophoresis. Eluted or cutout (2 X 2 mm) samples of radioactive components from paper chromatograms were separated by paper electrophoresis (10 V/cm) in a variety of buffer systems. The blue dye, indigotetrasulfonate, was used as a standard and applied as 2 X 2 mm samples onto the wet paper adjacent to each origin. RESULTSThin-layer chromatography of the CHCIa/MeOH extract of the marine diatom C. concavicornis revealed three main 74As-containing spots, lipid compounds I, II, and III (Table I). Four water-soluble compounds (A, B, C, and D) were resolved by two-dimensional paper chromatography of the water extract (Table 2 and Fig. 1).Both lipids I and II deacylated upon treatment with methanolic KOH. Chromatography revealed the identity of the deacylated compound and the naturally occurring compound B. Treatment of lipid I with phospholipase A2 produced a compound with the same RF as lipid II, implying that lipid II is the lyso form of lipid I.The deacylated lipid (B) was found to acetylate in acetic anhydride/pyridine. Both mono-and diacetylated products were bbserved by paper chromatography. Oxidation of B with NaIO4 resulted in a new compound with RF = 0.48. A compou...

A bioassay chamber was developed to evaluate the attraction of the phorid fly pest, Megaselia halterata (Wood) (Diptera, Phoridae), to volatiles from mushroom compost colonized by the commercial mushroom, Agaricus bisporus (Fungi, Agaricaceae) and to its volatile constituents, 1‐octen‐3‐ol and 3‐octanone. The bioassay chamber consisted of a large round container which was attached, via glass tubes, to three removable sample cups situated below the container. Once a fly had entered a sample cup, the flatly cut glass tubes prevented the flies from readily returning to the release chamber and, in effect, was a pit fall trap which kept the flies in the cups until the flies were counted. Holes in the bottom of the cups and removal of 20 ml of air from the chamber to fill the entrance tubes with volatiles from the cups were necessary for the success of the bioassay. Mated and unmated female M. halterata and, to a lesser extent, mated males preferred spawned compost (compost well colonized by fungal mycelia) relative to unspawned compost or blank cups. Unmated males were not attracted to spawned compost. Males and females were not attracted to unspawned compost. No attraction of male or female M. halterata to the spawned compost volatiles, 1‐octen‐3‐ol and 3‐octanone, could be demonstrated under various experimental conditions. These two compounds seemed to deter females at high concentrations.

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Compounds identified as sex attractant pheromones in a number of phytophagous insects were found in a variety of host plants. These agents vary in chemical composition in different plant species, which suggests that dietary factors may provide an evolutionary mechanism for diversification of certain insect species. A theoretical framework to explain this phenomenon is postulated on the basis of experiments with the oak leaf roller moth.

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