| | 1 | Author
| B. Ernd, F. Ussm, Ann, P. Ete, D. An | Requires cookie* | | | Title
| Polymerization of Actin in the Absence and Presence of Cytochalasin B: Problems of Determining "Critical Concentration"  | | | | Abstract
| A Various concentrations o f actin (0.3 or 1 mM MgCl2, 1 mM A T P , 1 mM E G T A) reached their final degree o f polym erization (m easured by a pyrene dye attached to actin) earlier in the pres ence o f cytochalasin B than in its absence. The curves relating concentrations o f polym eric F-actin to total actin concentration were under these conditions highly nonlinear making an unam biguous extrapolation to zero F-actin concentration (to deduce the "critical concentration" o f actin poly m erization) im possible. The concentration o f actin, above which polym erization occurred, was unaltered by cytochalasin B (although for reasons not yet understood the specific fluorescence intensity of polym erized actin was lower in the presence of cytochalasin B than in its absence). The results show that a distinct "critical concentration" o f actin polymerization must not always be well defined. | | | |
Reference
| Z. Naturforsch. 41c, 781 (1986); received April 23 1986 | | | |
Published
| 1986 | | | |
Keywords
| ctin, Cytochalasin B, Critical Concentration, Fluorescence, Polymerization | | | |
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| default:Reihe_C/41/ZNC-1986-41c-0781.pdf | | | | Identifier
| ZNC-1986-41c-0781 | | | | Volume
| 41 | |
| 2 | Author
| ThorB. Melø, Gro Reisaeter | Requires cookie* | | | Title
| Photodestruction of Endogenous Porphyrins in Relation to Cellular Inactivation of Propionibacterium acnes | | | | Abstract
| of Propionibacterium acnes on Eagles medium protoporphyrin was accumulated inside the cells and coproporphyrin, both as a free base as metalcontaining, outside the cells. The photochemical processes in the endogenous porphyrins were studied by fluorescence spectroscopy during continuous irradiation of Propionibacterium acnes in suspension. The irradiation caused initially an increase in the content of protoporphyrin in the cells in comparison to that which had been accumulated during growth. Maximum light induced protoporphyrin production was achieved in 5 days old cultures. In old cultures where there was practically no initial protoporphy rin release, the fluorescence intensities from all the porphyrins present in the culture vanished exponentially with the irradiation time. The metal containing form of fluorescent coproporphyrin, with a maximum emission at 580 nm, was photobleached about ten times faster than the free base forms of coproporphyrin and protoporphyrin. Among these three fluorescent substances in the cell culture only the free base forms of the porphyrins have longer lifetimes than the cells themselves irradiated at the same conditions. | | | |
Reference
| Z. Naturforsch. 41c, 867 (1986); received February 28/June 3 1986 | | | |
Published
| 1986 | | | |
Keywords
| Propionibacterium acnes, Porphyrins, Photooxidation, Fluorescence, Survival During growth | | | |
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| default:Reihe_C/41/ZNC-1986-41c-0867.pdf | | | | Identifier
| ZNC-1986-41c-0867 | | | | Volume
| 41 | |
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