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AMBIENTUM BIOETHICA BIOLOGIA CHEMIA DIGITALIA DRAMATICA EDUCATIO ARTIS GYMNAST. ENGINEERING EPHEMERIDES EUROPAEA GEOGRAPHIA GEOLOGIA HISTORIA HISTORIA ARTIUM INFORMATICA IURISPRUDENTIA MATHEMATICA MUSICA NEGOTIA OECONOMICA PHILOLOGIA PHILOSOPHIA PHYSICA POLITICA PSYCHOLOGIA-PAEDAGOGIA SOCIOLOGIA THEOLOGIA CATHOLICA THEOLOGIA CATHOLICA LATIN THEOLOGIA GR.-CATH. VARAD THEOLOGIA ORTHODOXA THEOLOGIA REF. TRANSYLVAN
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The STUDIA UNIVERSITATIS BABEŞ-BOLYAI issue article summary The summary of the selected article appears at the bottom of the page. In order to get back to the contents of the issue this article belongs to you have to access the link from the title. In order to see all the articles of the archive which have as author/co-author one of the authors mentioned below, you have to access the link from the author's name. |
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STUDIA BIOLOGIA - Issue no. 2 / 2012 | |||||||
Article: |
THE EFFECT OF VARIOUS LIGHT INTENSITIES ON PHOTOSYSTEM II PHOTOCHEMISTRY IN THE CYANOBACTERIUM SYNECHOCYSTIS sp. PCC 6803. Authors: BOGDAN DRUGĂ, VICTOR BERCEA, COSMIN IONEL SICORA. |
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Abstract: The cyanobacterium Synechocystis sp. PCC 6803 grown on BG 11 medium under air bubbling was exposed to high light intensities of 2000, 3000 and 4500 µmol.m-2.s-1 while being in the exponential growth phase. The effect of light treatment was assessed after 15, 30, 45, 60, 75, 90, 105 and 120 minutes by monitoring chlorophyll fluorescence. F0, Fm, Fv/Fm and Y(II) have significantly decreased under high light. The enhancement of the quantum yield of non-regular energy dissipation Y(NO) indicates that both the conversion of photochemical energy and the protective regulating mechanisms are inefficient. The increase of Y(NO) certifies the intensification of dissipation processes which take place mainly in the light harvesting antenna, in phycobilisomes. The high light intensities have led to the photoinhibition of the photosystem (PS) II antenna, affecting the reaction centers because Fv/Fm was decreased. The recovery of PSII photochemical activity was in overall a slow process correlated with light intensity that was used. Keywords: chlorophyll fluorescence; coefficient of photochemical quenching (qP, qL); effective PS II quantum yield (YII); fluorescence yield; minimal fluorescence; maximal fluorescence; maximal PS II quantum yield (Fv/Fm); quantum yield of non-regulated energy dissipation (YNO); recovery. |
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