Prostaglandin (15S)-PGA2 derivatives in the gorgonianPlexaura homomalla (Esper), formakükenthali Moser

Summary The lipid fraction, 17%, of air-driedPlexaura homomalla formakükenthali, collected in the Caribbean at Puerto Rico, yielded 50% of its weight as the mammalian prostaglandin (15S)-PGA₂ methyl ester. The freeze-dried gorgonian yielded (15S)-PGA₂ largely as the acetate of the methyl ester. (15S)-PGA₂ was also obtained from material collected at St. Croix and at South Caicos. Field observations indicate thatPlexaura kükenthali may be a species separate fromPlexaura homomalla and that it is abundant on some shallow water reefs in the Caribbean. Prostaglandins could not be detected in the lipid fraction of eggs isolated fromPlexaura homomalla (Esper) formahomomalla.Acknowledgments. We gratefully acknowledge support from the Office of Sea Grant, NOAA, Department of Commerce (Grant 047-158-44067), and the use of facilities at the Isla Mayagues Marine Laboratory of the University of Puerto Rico, Mayaguez, the West Indies Laboratory of Fairleigh Dickinson University at St. Croix, U.S.V.I., and the Marine-Biologisch Instituut at Curacao. Special thanks to Dr. F.M. Bayer, Curator, Department of Zoology, National Museum of Natural History-Smithsonian Institution for checking identity of gorgonians used in this study.     

A simplified method of nerve organ culture

Résumé Une méthode simplifiée de culture d'organe nerveux est décrite. Elle réduit le temps consacré à la nourriture et permet un changement rapide du milieu nutritif. Elle convient aux études microscopique (m. à contraste de phase) et elle est relativement peu coûteuse.     

A large anion-selective channel has seven conductance levels

Ion channels have generally been found to have two predominant conductance levels thought to be associated with 'open' and 'closed' states, but intermediate (subconductance) states have also been reported. We have now found that a large conductance, anion-selective channel in pulmonary alveolar epithelial cells can adopt any of six open levels of conductance that are integer multiples of 60-70 pS. The channel is usually either fully open or fully closed. The frequencies of the different conductance levels are inconsistent with the notion that there are six independent channels. We suggest that the channel consists of six conducting pathways in parallel, 'co-channels', with a shared gating mechanism that can synchronously render all of them non-conducting. Other channels with lower maximum conductance may operate in a similar way but multiple conductance levels would not easily be detected because of a less favourable signal-to-noise ratio.