Cruoriella rhodoliths from shallow-water back reef environments in La Parguera, Puerto Rico (Caribbean Sea)

The occurrence of shallow-water (0.9 to 1.3 m) rhodoliths in back reef environments in southwest Puerto Rico is reported. The rhodoliths were generally cylindrical, discoidal or irregular in shape with an average longest dimension of 7.2 cm. They occurred at a maximum density of 524 m⁻². The rhodoliths were composed of mostly coral nuclei with concentric laminations of aragonite-producing Cruoriella armorica (Peyssonneliaceae, Rhodophyta). Maximum Cruoriella accretion around coral nuclei was 30 mm although accretions of 1 to 20 mm were more common. Based on measurements of Cruoriella accretion, these shallow water rhodoliths are estimated to have minimum ages of 12 to 24 years. It is further estimated that approximately 2% of the rhodoliths are turned over daily. Accepted: 1 October 1999     

Isolation and characterisation of a soluble active fragment of hydrogenase isoenzyme 2 from the membranes of anaerobically grown Escherichia coli

An active tryptic fragment of membrane-bound hydrogenase isoenzyme 2 from anaerobically grown Escherichia coli has been purified. The soluble enzyme derivative was released from the membrane fraction by trypsin cleavage. The purification procedure involved ion-exchange, hydroxyapatite and gel permeation chromatography. The enzyme derivative was purified 100-fold from the membrane fraction and the specific activity of the final preparation was 320 mumol benzyl viologen reduced min-1 mg protein-1 (H2:benzyl viologen oxidoreductase). The native enzyme derivative had an Mr of 180,000 and was composed of equimolar amounts of polypeptides of Mr 61,000 and 30,000. It possessed 12.5 mol Fe, 12.8 mol acid-labile S2- and 3.1 mol Ni/180,000 g enzyme. Antibodies were raised to the purified preparation which cross-reacted with hydrogenase isoenzyme 2 but not with isoenzyme 1 in detergent-dispersed preparations. Western immunoblot analysis revealed that isoenzyme 2 which had not been exposed to trypsin contained cross-reacting polypeptides of Mr 61,000 and 35,000. Trypsin treatment of the membrane-bound enzyme to form the soluble derivative of isoenzyme 2, therefore, cleaves a polypeptide of Mr 35,000 to produce the 30,000-Mr fragment. Trypsin treatment of the detergent-dispersed isoenzyme 2 produces the same fragmentation of the enzyme. Neither of the subunits of the enzyme revealed any immunological identity with those of hydrogenase isoenzyme 1.     

Effects of culture conditions on production of antibiotically active metabolites by the marine alga Spyridia filamentosa (Ceramiaceae, Rhodophyta). I. Light

The effect of irradiance over the range 5 to 70 μmol photon m-2 s-1 on production of antibiotically active metabolites was assessed for male and female gametophytes and tetrasporophytes of the red alga Sphyridia filamentosa (Wulfen) Harvey in Hooker in culture. Whole-algal extracts and ten recognizable TLC-separable zones were assayed against five human microorganisms pathogenic to humans. For all experimental irradiance conditions, the ten TLC zones displayed activity against four of the microorganisms. The maximum number of TLC zones with activity under any of the culture conditions was six each for male and female Spyridia at 70 μmol photon m-2 s-1. Small changes in irradiance resulted both in different activities against specific microorganisms and degree of activity. The fact that every TLC zone showed differing activities at different light conditions or when extracted from different life history stages strongly suggests the presence of multiple antibiotic principals in individual TLC zones. This revised version was published online in June 2006 with corrections to the Cover Date.     

Sterols of the phytoplankton—effects of illumination and growth stage

The sterol compositions of different species of cultured phytoplankton, (two diatoms—Phaeodactylum tricornutum and Skeletonema costatum, two green algae—Danaliella minuta and Tetraselmis tetrathele and a brown alga—Monochrysis lutheri) were compared with that of a diatom field population ( > 98 % Thalassionema nitzschioides) using GC-MS techniques. The effect of culture age in the cultured specimen; was examined by harvesting in both the exponential and stationary growth phases and was found to produce considerable differences in the sterol composition in some species. The influence of the intensity and different spectral illumination on a cultured specimen of a green alga (Danaliella minuta) was also examined and found to produce changes in the sterol composition.     

Benthic cyanobacterial, Microcoleus lyngbyaceus, blooms in shallow, inshore Puerto Rican Seagrass habitats, Caribbean sea

Biomass and cover of Microcoleus lyngbyaceus (Kützing) Crouan were monitored at inshore seagrass habitats in southwest Puerto Rico for 16 months. Substantial localized blooms with maximum cover of 100% and comprising >600 g/m² were encountered. Abundance of Microcoleus (biomass and percent cover) were not significantly correlated with either water temperature or water column nitrogen (as nitrate and nitrite concentrations). M. lyngbyaceus has locally been implicated as being detrimental to the seagrass Thalassia testudinum König which is supported by circumstantial evidence. Thalassia cover declined in permanent quadrats that were strongly impacted with Microcoleus.     

Quinolines as a novel structural class of potent and selective PDE4 inhibitors. Optimisation for inhaled administration

Crystallography driven optimisation of a lead derived from similarity searching of the GSK compound collection resulted in the discovery of quinoline-3-carboxamides as highly potent and selective inhibitors of phosphodiesterase 4B. This series has been optimized to GSK256066, a potent PDE4B inhibitor which also inhibits LPS induced production of TNF-α from isolated human peripheral blood mononuclear cells with a pIC₅₀ of 11.1. GSK256066 also has a suitable profile for inhaled dosing.     

Nickel-containing hydrogenase isoenzymes from anaerobically grown Escherichia coli K-12.

Two membrane-bound hydrogenase isoenzymes present in Escherichia coli during anaerobic growth have been resolved. The isoenzymes are immunologically and electrophoretically distinct. The physically more abundant isoenzyme (hydrogenase 1) contains a subunit of Mr 64,000 and is not released from the membrane by exposure to either trypsin or pancreatin. The second isoenzyme (hydrogenase 2) apparently contributes the greater part of the membrane-bound hydrogen:benzyl viologen oxidoreductase activity and exists in two electrophoretic forms revealed by nondenaturing polyacrylamide gel analysis. This isoenzyme is irreversibly inactivated at alkaline pH and gives rise to an active, soluble derivative when the membrane-bound enzyme is exposed to either trypsin or pancreatin. Both hydrogenase isoenzymes contain nickel.