A preliminary assessment of the techniques for measuring primary production in macrophytic marine algae

Résumé En employant les méthodes de la production d'oxygène et de l'assimilation du¹⁴C, on a estimé la productivité primaire de l'algue,Caulerpa prolifera, in situ à profondeurs variés aux îles Canaries. On a jugé les mérites respectives des 2 techniques et a comparé les résultats avec ceux des autres auteurs.

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This work is part of a programme of investigation of the ecological distribution and primary productivity of benthic marine macrophytes in the Canary Island region.     

Chlorophyll breakdown in higher plants and algae

Leaf senescence is accompanied by the metabolism of chlorophyll (Chl) to nonfluorescent catabolites (NCCs). The pathway of Chl degradation comprises several reactions and includes the occurrence of intermediary catabolites. After removal of phytol and the central Mg atom from Chl by chlorophyllase and Mg dechelatase, respectively, the porphyrin macrocycle of pheophorbide (Pheide) a is cleaved. This two-step reaction is catalyzed by Pheide a oxygenase and RCC reductase and yields a primary fluorescent catabolite (pFCC). After hydroxylation and additional species-specific modifications, FCCs are tautomerized nonenzymically to NCCs inside the vacuole. Different subcellular compartments participate in Chl catabolism and, thus, transport processes across membranes are required. This review focuses on the catabolites and the individual reactions of Chl breakdown in higher plants. In addition, the pathway is compared to Chl conversion to red catabolites in an alga, Chlorella protothecoides. Finally, the significance and regulation of Chl degradation are discussed.     

Chemical control of eucaryotic and blue-green algae in anaerobic photoreactors culturing Rhodospirillaceae

Summary To control the growth of eurocaryotic and blue-green algae in anaerobic reactors of photosynthetically grown Rhodospirillaceae, the effect of algae inhibitors with different modes of action was examined. Tests were performed with mixed populations of green algae and blue-green algae, besides strains of the purple nonsulphur bacteriaRhodopseudomonas capsulata, Rhodospirillum rubrum andRhodomicrobium vannielii. Chloroxuron, a urea-derivative, was found to inhibit completely growth of green and blue-green algae at 5 ppm. When it was applied to the Rhodospirillaceae cultures, growth was not reduced and nitrogenase activity was not inhibited.     

Rickettsial infection in marine crustacea

Summary A rickettsial disease is described in the crabCarcinus mediterraneus Czerniavski. The pathogen develops within vacuoles in connective tissue cells. 2 morphologically different forms are observed in the last stage of infection. The systematic position of this procaryote is discussed.This work was performed within the framework of a CNEXO-INRA agreement.     

Spermatozoid-attracting substance in hermaphrodite brown algae,Pelvetia wrightii andFucus evanescens

Summary A spermatozoid-attracting substance of the hermaphrodite brown algae,Pelvetia wrightii andFucus evanescens, was identified as 1, trans-3, cis-5-octatriene, respectively, by¹H-NMR and¹³C-NMR data and biological activities.Acknowledgments. The authors would like to express their thanks to Mr A. Nishikawa for technical assistance, to Dr M. Abe (Yamagata Univ.) for valuable discussion on biological work and to Prof. Y. Sakai (Hokkaido Univ. Director of the Institute of Algological Research, Muroran) for the facilities during the investigation ofP. wrightii andF. evanescens. Financial support from the Ministry of Education Science, and Culture (Grant-in Aid for Scientific Research No. 556092) is gratefully acknowledged.     

Transformations of arsenic in the marine environment

Summary It is ten years since arsenobetaine was first isolated from the western rock lobsterPalinurus cygnus. Subsequently this naturally-occurring arsenical has been found in many species of marine animals contributing to the human diet. The identification of arsenic-containing ribofuranosides in algae and the production of dimethylarsinoylethanol from their anaerobic decomposition has allowed speculation on arsenic metabolism in marine organisms and has suggested a possible route to arsenobetaine from oceanic arsenate.     

Antimicrobial metabolites of the marine spongeAxinella polycapella

Summary Extracts of the marine spongeAxinella polycapella contain 1,2,4-trihydroxybenzene (1) and 2,2,4,4,5,5-hexahydroxybiphenyl (3) as antimicrobial constituents. Methods of synthesizing3 by, oxidative dimerization of1 were examined.Acknowledgment. We are grateful to Dr Klaus Reutzler for identifying the sponge and one of us (SW) is pleased to acknowledge fellowship support (1-F32-AI_05883-02) from the Public Health Service.     

Transformations of arsenic in the marine environment

It is ten years since arsenobetaine was first isolated from the western rock lobster Palinurus cygnus. Subsequently this naturally-occurring arsenical has been found in many species of marine animals contributing to the human diet. The identification of arsenic-containing ribofuranosides in algae and the production of dimethylarsinoylethanol from their anaerobic decomposition has allowed speculation on arsenic metabolism in marine organisms and has suggested a possible route to arsenobetaine from oceanic arsenate.     

Chloroplast nucleoids in a unicellular hot spring algaCyanidium caldarium and related algae

Summary Algal chloroplast nucleoids were compared by epifluorescent microscopy.Cyanidium caldarium strain RK-1 or 001 has a rod-shaped chloroplast nucleoid whileCyanidium caldarium (Chroococcidiopsis sp.) strain M-8 or 002 has a circular chloroplast nucleoid along the periphery of a multilobed chloroplast.     

Allantoinase in the marine polychaeteEudistylia vancouveri

Summary Allantoinase, an enzyme in the purine-urea cycle, was found inEudistylia vancouveri (Polychaeta). The enzyme had a pH optimum at 7.6 TheK _m was 0.012M allantoin, and the Arrhenius energy of activation was 12.6 to 14.6 kcal/mol.Supported by the U. S. National Science Foundation (Institutional Grant) and by the U. S. Environmental Protection Agency Grant No. T-900204 (WP-175). Publication No. 10 of the Laboratory of Biochemical Ecology; College of Fisheries Contribution No. 458. We thank Dr.Robert L. Fernald for generously making available to us the facilities of the Friday Harbor Laboratories, Friday Harbor, Washington.