| 1. |
- Bailleul, Benjamin, et al.
(author)
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Energetic coupling between plastids and mitochondria drives CO2 assimilation in diatoms.
- 2015
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 524:7565, s. 366-9
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Journal article (peer-reviewed)abstract
- Diatoms are one of the most ecologically successful classes of photosynthetic marine eukaryotes in the contemporary oceans. Over the past 30 million years, they have helped to moderate Earth's climate by absorbing carbon dioxide from the atmosphere, sequestering it via the biological carbon pump and ultimately burying organic carbon in the lithosphere. The proportion of planetary primary production by diatoms in the modern oceans is roughly equivalent to that of terrestrial rainforests. In photosynthesis, the efficient conversion of carbon dioxide into organic matter requires a tight control of the ATP/NADPH ratio which, in other photosynthetic organisms, relies principally on a range of plastid-localized ATP generating processes. Here we show that diatoms regulate ATP/NADPH through extensive energetic exchanges between plastids and mitochondria. This interaction comprises the re-routing of reducing power generated in the plastid towards mitochondria and the import of mitochondrial ATP into the plastid, and is mandatory for optimized carbon fixation and growth. We propose that the process may have contributed to the ecological success of diatoms in the ocean.
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| 2. |
- Finazzi, Giovanni, et al.
(author)
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Ions channels/transporters and chloroplast regulation.
- 2015
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In: Cell Calcium. - : Elsevier BV. - 0143-4160 .- 1532-1991. ; 58:1, s. 86-97
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Journal article (peer-reviewed)abstract
- Ions play fundamental roles in all living cells and their gradients are often essential to fuel transports, to regulate enzyme activities and to transduce energy within and between cells. Their homeostasis is therefore an essential component of the cell metabolism. Ions must be imported from the extracellular matrix to their final subcellular compartments. Among them, the chloroplast is a particularly interesting example because there, ions not only modulate enzyme activities, but also mediate ATP synthesis and actively participate in the building of the photosynthetic structures by promoting membrane-membrane interaction. In this review, we first provide a comprehensive view of the different machineries involved in ion trafficking and homeostasis in the chloroplast, and then discuss peculiar functions exerted by ions in the frame of photochemical conversion of absorbed light energy.
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