Biology subjects

TOLLETER, D.

Publications and source records attributed to TOLLETER, D..

2 recordsLinked to original sources

bioRxiv2025

A Mitochondrially Derived Plastidial Transporter Regulates Photosynthesis in the Diatom Phaeodactylum tricornutum

Eukaryotic phototrophs depend on the activity of two engines (the plastid and the mitochondrion) to generate the energy required for cellular metabolism. Because of their overlapping functions, both activities must be closely coordinated. At the plastid level, optimization occurs through alternative electron transport, the diversion of excess electrons from the linear transport chain, and metabolic exchanges. A similar process takes place in the mitochondria, with documented evidence of energy and redox equivalents being exchanged between the two organelles. Organelle-organelle energy interactions at the physiological level are well established in diatoms, an ecologically significant member of phytoplankton. Yet the molecular components involved in this process remain largely unknown. Here, we identify a Mitochondrial Carrier Family (MCF) transporter, MCFc, located at the plastid envelope of Phaeodactylum tricornutum, which seems to be widely distributed in complex algae. We then compare the performance of a wild-type and a mutant lacking MCFc. An analysis of spectroscopic and oxygen exchange data unveiled altered energetic interactions in the mutant, suggesting that MCFc, plays a role in plastid-mitochondrion communication. In silico analysis of MCFc implies a similar substrate-specific model to that of ADP/ATP carriers, although distinct motif differences in MCFc indicate potential variations in its function, with possible substrates including arginine, aspartate/glutamate, or citrate. These findings illuminate how mitochondrial energy contributes to fueling diatom photosynthesis.

plant biology↗

bioRxiv2022

Tailoring confocal microscopy for in-cell photophysiology studies

Photoautotrophs environmental responses have been extensively studied at the organism and ecosystem level. However, less is known about their photosynthesis at the single cell level. This information is needed to understand photosynthetic acclimation processes, as light changes as it penetrates cells, layers of cells or organs. Furthermore, cells within the same tissue may behave differently, being at different developmental/physiological stages. Here we describe a new approach for single-cell and subcellular photophysiology based on the customisation of confocal microscopy to assess chlorophyll fluorescence quenching by the saturation pulse method. We exploit this setup to: i. reassess the specialisation of photosynthetic activities in developing tissues of non-vascular plants; ii. identify a specific subpopulation of phytoplankton cells in marine photosymbiosis, which are consolidating metabolic connections with their animal hosts, and iii. testify to the link between light penetration and photoprotection responses inside the different tissues that constitute a plant leaf anatomy. MotivationVisualising photosynthetic responses in 3D is essential for understanding most acclimation processes, as light changes within photosynthetic tissues as it penetrates the absorbing/diffusing layers of the cells. To achieve this goal, we developed a new imaging workflow merging confocal microscopy and saturating pulse chlorophyll fluorescence detection. This method applies to samples characterised by increasing complexity and its simplicity will contribute to its widespread use in plant and microalgae photoacclimation studies.

plant biology↗