PubMed · 7577301
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M Goerig. 1995. Fires and explosions.. https://doi.org/10.1093/bja%2F75.5.666-b
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Ten acetylenic enol ethers of glycerols, including six new compounds (1-6) and a linear acetylenic alcohol (7), have been isolated from a sponge of the genus Petrosia. The structures of the novel compounds were elucidated by spectroscopic methods. The absolute stereochemistry of 1-7 was determined by chemical transformations and the Mosher method. Some of these compounds exhibited weak cytotoxicity against a human leukemia cell-line (K-562).
The filamentous cyanobacteria Symploca PCC 8002 (Symploca) and Trichodesmium spp. fix nitrogen aerobically in the light in a light/dark cycle, without forming specialized thick-walled cells (heterocysts). Even though they do not form heterocysts, we amplified and sequenced a segment of a key regulatory gene in heterocyst differentiation, the hetR gene, from Symploca, Trichodesmium erythraeum and Leptolyngbya PCC 73110 (which fixes nitrogen anaerobically) using degenerate oligonucleotides. The transcriptional level of hetR in Symploca PCC 8002 was examined in relation to nifH expression during nitrogen step-down. The expression pattern of hetR suggests that it was not induced during removal of combined nitrogen, as is the case with the heterocystous cyanobacteria. This is the first report of sequences corresponding to a portion of hetR from within the group of non-heterocystous cyanobacteria.
Pyruvate:ferredoxin (flavodoxin) oxidoreductase (POR) was purified 3050-fold to apparent homogeneity from the photosynthetic bacterium Rhodobacter capsulatus using ion-exchange, Reactive Red, and gel filtration chromatography. The isolated enzyme was sensitive to dilution and oxygen (especially when in dilute solution). The molecular mass of the native enzyme was determined by high performance liquid chromatography gel filtration to be 270+/-20 kDa. Since a subunit molecular mass of 130+/-5 kDa was found by denaturing gel electrophoresis, POR from R. capsulatus thus appears to be a homodimer. Electron paramagnetic resonance analysis showed that a free radical was formed upon the addition of pyruvate. This POR is shown to be an indiscriminate electron donor causing the full reduction of R. capsulatus flavodoxin (Fld), R. capsulatus ferredoxin I (FdI), R. capsulatus ferredoxin II (FdII), as well as the major plant-type ferredoxin (FdI) from Anabaena variabilis. The purified enzyme can couple the oxidation of pyruvate to the reduction of nitrogenase in a coupled system with either R. capsulatus ferredoxins or nif-specific flavodoxin, NifF; (Fld>FdI>FdII). Immunoblot analysis shows that R. capsulatus POR is constitutively synthesized, with synthesis augmented under nitrogen-fixing conditions (34+/-13%) and decreased in acetate and aerobically grown cells.