| 1. |
- Funk, Christiane, et al.
(author)
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D1' centers are less efficient than normal photosystem II centers
- 2001
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In: FEBS Letters. - 0014-5793 .- 1873-3468. ; 505:1, s. 113-117
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Journal article (peer-reviewed)abstract
- One prominent difference between the photosystem II (PSII) reaction center protein D1 ' in Synechocystis 6803 and normal D1 is the replacement of Phe-186 in D1 with leucine in D1 '. Mutants of Synechocystis 6803 producing only D1 ', or containing engineered D1 proteins with Phe-186 substitutions, were analyzed by 77 K fluorescence emission spectra, chlorophyll a fluorescence induction yield and decay kinetics, and flash-induced oxygen evolution. Compared to D1-containing PSII centers, D1 ' centers exhibited a 50% reduction in variable chlorophyll a fluorescence yield, while the flash-induced O-2 evolution pattern was unaffected. In the F186 mutants, both the P680(+)/Q(A)(-) recombination and O-2 oscillation pattern were noticeably perturbed.
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| 2. |
- Schofield, Scott C, et al.
(author)
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Changes in macromolecular allocation in nondividing algal symbionts allow for photosynthetic acclimation in the lichen Lobaria pulmonaria
- 2003
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In: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 159:3, s. 709-18
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Journal article (peer-reviewed)abstract
- The lichen Lobaria pulmonaria survives large seasonal environmental changes through physiological acclimation to ambient conditions.We quantitated algal cell population, cell division and key macromolecular levels associated with photosynthesis and nitrogen metabolism in L. pulmonaria sampled from four seasons with contrasting environmental conditions in a deciduous forest.The algal symbiont population did not vary seasonally and cell division was restricted to the newest thallus margins. Nevertheless the symbiont concentrations of chlorophyll, PsbS, PsbA, and RbcL changed significantly through the seasons in the nondividing algal cells from older thallus regions.L. pulmonaria reversibly allocated resources toward photochemical electron generation and carbohydrate production through the spring, summer and fall, and towards photoprotective dissipation in the cold, high-light winter. Our study shows that large seasonal molecular acclimation in L. pulmonaria occurs within a nearly stable, nondividing algal cell population that maintains photosynthetic capacity through many years of changing environmental cues.
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