| | 2 | Author
| N. Orbert, A. Dencher, Eilo Hildebrand | Requires cookie* | | | Title
| Sensory Transduction in Halobacterium halobium: Retinal Protein Pigment Controls UV-Induced Behavioral Response  | | | | Abstract
| Both photosystems, PS 370 and PS 565, controlling behavioral responses in H alobacterium halo-bium [E. Hildebrand and N. Dencher, Nature 2 5 7 ,4 6 — 48 (1975)] are reversibly inhibited when bacteria are grown in the presence o f 1 mM nicotine which is known to block biosynthesis o f reti nal. Photobehavior can be restored within som e minutes to hours by adding retinal to nicotine-treated bacteria, PS 370 thereby reappearing earlier than PS 565. The reconstitution rate depends on the concentration and on the kind o f retinal isomers applied. A \\-trans retinal is m ost effective. PS 370 becomes fully sensitive if reconstituted in the presence o f nicotine. This rules out the possi bility that the alkaloid may directly inhibit steps o f signal transmission follow ing photoreception. The action spectrum o f PS 370 regenerated with retinal alone o f H. h., strain RjLg (a mutant deficient in carotenoids), fails to show all secondary peaks around 450 nm which in strain Rj occur besides the prominent maximum at 370 nm. A ddition o f carotenoids (m ainly a-bacterioruberin) to reconstituted cells o f R ,L3 restores the sensitivity in that spectral region. Carotenoids or flavin solely added to nicotine-treated bacteria cannot restore photobehavior. We conclude that the active pigm ent o f PS 370, which m ediates the photophobic response to increase o f light intensity (step-up response), represents a retinal protein com plex and that carote noids participate in photoreceptor function as accessory pigments. The biochem ical relation o f the UV-absorbing retinal protein com plex to bacteriorhodopsin is discussed. | | | |
Reference
| Z. Naturforsch. 34c, 841 (1979); received June 5/July 6 1979 | | | |
Published
| 1979 | | | |
Keywords
| Bacteria, Photophobic Response, Bacteriorhodopsin, Carotenoids, Accessory Pigment | | | |
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| default:Reihe_C/34/ZNC-1979-34c-0841.pdf | | | | Identifier
| ZNC-1979-34c-0841 | | | | Volume
| 34 | |
| 3 | Author
| M. Wink | Requires cookie* | | | Title
| Chemical Defense of Leguminosae. Are Quinolizidine Alkaloids Part of the Antimicrobial Defense System of Lupins? | | | | Abstract
| Growth o f 6 bacteria (Serratia marcescens, Bacillus megaterium , Bacillus subtilis, Streptococcus viridis, Micrococcus luteus, and M ycobacterium ph lei) was inhibited by 50% if the growth m edium contained sparteine at concentrations between 0 .5 -1 0 m M . Total growth inhibition, which was bacteriostatic in nature, was achieved at 20 m M . The growth o f 6 phytopathogenic fungi was also affected: at a sparteine concentration o f 15 m M the growth o f Alternaria porri was reduced by 40% as compared to the untreated control. R espective values were 18% inhibition for Piricularia oryzae, 33% for H elminthosporium carbonum, 15% for R hizoctonia solani, 5% for Fusarium oxysporum, and 42% for Asperquillus oryzae. Since the concentrations o f quinolizidine alkaloids range from 1 -2 0 0 m M (roots, leaves, or stems) or 1 0 -2 0 0 m m ol/k g (seeds) in Legum inosae, it is discussed whether quinolizidine alkaloids are involved in the antim icrobial defense o f lupins, in addition to their potential role as allelopathic or herbivore repellent defense com pounds. | | | |
Reference
| Z. Naturforsch. 39c, 548 (1984); received January 23 1984 | | | |
Published
| 1984 | | | |
Keywords
| Quinolizidine Alkaloids, Growth Inhibition, Bacteria, Fungi, Antim icrobial Defense | | | |
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| default:Reihe_C/39/ZNC-1984-39c-0548.pdf | | | | Identifier
| ZNC-1984-39c-0548 | | | | Volume
| 39 | |
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