Biology subjects

De Angeli, A.

Publications and source records attributed to De Angeli, A..

7 recordsLinked to original sources

bioRxiv2026

Cracking vacuolar fumarate and malate transport shows its function in Arabidopsis metabolism and growth.

Malate and fumarate constitute a significant transient carbon stock that is dynamically synthesized during the photoperiod. These organic acids are diurnally stored and remobilised from the vacuole, and they have a key role in the cellular metabolic regulation. This function is well known in C4 and CAM plants. However, in C3 species that are the majority of terrestrial plants, the importance of the vacuolar accumulation/release and its influence on plant growth is still an open question. In Here we addressed this issue generating multiple knockout mutants in Arabidopsis thaliana lacking vacuolar anion channels of the Aluminium-Activated Malate Transporter (ALMT) family, to impair malate and fumarate transport to the vacuole. We show that in these mutants reducing vacuolar transport of malate and fumarate in mesophyll cells leads to a dramatic growth impairment. Metabolic and fluxomic analysis revealed that vacuolar malate and fumarate transport influences plant carbon and nitrogen metabolism as well as cellular pH and ionic homeostasis. In conclusion, our results show that the transport organic acids like malate and fumarate across the vacuolar membrane is essential for plant growth in a C3 plant too. These results establish the importance of the vacuolar pools of malate and fumarate in plant metabolism.

plant biology↗

bioRxiv2025

Multi-physics modeling for ion homeostasis in multi-compartment plant cells using an energy function

Plant cells control their volume by regulating the osmotic potential of their cytoplasm and vacuole. Water is attracted into the cell as the result of a cascade of solute exchanges between the cell subcompartments and the cell surroundings, which are governed by chemical, electrostatic and mechanical forces. Due to this multi-physics aspect and to couplings between changes of volumes and chemical effects, modeling these exchanges remains a challenge that has only been partially adressed. In this paper, we introduce an energy-based approach to couple chemical, electrical and mechanical processes taking place between several subcompartments of a plant cell. The contributions of all physical effects are gathered in an energy function that allows us to derive the equations satisfied by each variable in a systematical way. This results in a modular, unified approach that can be interpreted analytically. We illustrate these properties on the modeling of ion and water transport in a guard cell during stoma opening. We represent the stoma opening process as a quasi-static evolution driven by hydrogen pumps in the plasma and vacuolar membranes, resulting in an interpretable model with few parameters. We perform numerical simulations to investigate the role of each hydrogen pump in this process. We show that this energy-based approach allows us to highlight a hierarchy between the forces involved in the system, that can be exploited to interpret the emergent properties of this complex multi-physics system.

biophysics↗

bioRxiv2024

Overexpressing NRT2.7 induces nitrate export from the vacuole and increases growth of Arabidopsis

Nitrogen nutrition is essential for crop yield but applying fertilizers has detrimental effects on the environment. Compartmenting nitrate into vacuoles is one of the options to develop Nitrogen-efficient crop adapted to less fertilizers. Only few proteins involved in nitrate transport on the tonoplast have been identified. CLCa is the major transporter involved in nitrate storage in Arabidopsis but it can also facilitate nitrate remobilization from the vacuole in guard cells. Several other nitrate transporters amongst NRT2.7 have been localized in this membrane. The transport mechanism of NRT2.7 has not yet been defined as this protein is present mainly in seed cells that are not easily amenable for electrophysiology analysis. Here, we investigated NRT2.7 function through its ectopic overexpression in a clca knock-out mutant. Although the growth diminution of clca on nitrogen sufficient medium was complemented, nitrate homeostasis was not restored by NRT2.7 activity. Moreover, NRT2.7 ectopic overexpression in wild-type background (WT) increased growth under limiting nitrogen supply, suggesting that NRT2.7 stimulates nitrate efflux from vacuoles. This hypothesis was demonstrated by electrophysiological nitrate flux measurements on isolated vacuoles. This discovery of NRT2.7 function and more largely the coupling of vacuolar nitrate fluxes with growth under low nitrate supply, will enable new strategies for engineering better NUE for a more sustainable agriculture. HighlightThe overexpression of the nitrate transporter NRT2.7 stimulates growth by increasing the export of nitrate from the vacuole, the main cell compartment for nitrate storage.

plant biology↗

bioRxiv2022

ALMT-independent guard cell R-type anion currents

Plant transpiration is controlled by stomata, with S- and R-type anion channels playing key roles in guard cell action. Arabidopsis mutants lacking the ALMT12/QUAC1 R-type anion channel function in guard cells show only a partial reduction in R-type channel currents. To identify the molecular nature of the remaining R-type anion channel population, patch clamp studies were performed. This R-type current fraction in the almt12 mutant exhibited the same voltage dependence, susceptibility to ATP block and lacked a chloride permeability as the wildtype. Therefore, we asked whether the R-type anion currents in the ALMT12/QUAC1-free mutant are caused by additional ALMT isoforms. In wildtype guard cells ALMT12, ALMT13 and ALMT14 transcripts were detected, whereas only ALMT13 was found expressed in the almt12 mutant. Substantial R-type anion currents still remained active in the almt12/13 and almt12/14 double mutants as well as the almt12/13/14 triple mutant. This situation, supported by transpiration measurements, suggests that, with the exception of ALMT12, channel species other than ALMTs carry the guard cell R-type anion currents.

plant biology↗

bioRxiv2022

Proton exchange in the nitrate vacuolar transporter AtCLCa is required for growth and nitrogen use efficiency

Nitrate is a major nutrient and osmoticum for plants. To deal with its fluctuating availability in soils, plants store it into vacuoles. AtCLCa, a 2NO3-/1H+ exchanger localized on the vacuole ensures this storage process. It belongs to the CLC family that includes exchangers and channels. A mutation in a glutamate residue conserved across CLC exchangers is likely responsible for the conversion of exchangers to channels. Here, we show that a clca mutant of this residue, E203, behaves as an anion channel in its native membrane. To investigate its physiological importance, we introduced the AtCLCaE203Apoint mutation in a clca KO mutant. We first showed that these AtCLCaE203A mutants display a growth deficit linked to water homeostasis disruption. Additionally, AtCLCaE203Aexpression is not able to complement the clca defect in nitrate accumulation and favors higher N-assimilation at the vegetative stage. Further analyses at post-flowering stages indicated that AtCLCaE203A results in an increase of N uptake allocation to seeds, leading to a higher nitrogen use efficiency compared to wild-type. Altogether, these results point out the critical function of the AtCLCa exchanger on the vacuole for plant metabolism and development.

plant biology↗

bioRxiv2019

Dynamic measurement of cytosolic pH and uncovers the role of the vacuolar transporter AtCLCa in the control of cytosolic pH.

Ion transporters are key players of cellular processes. The mechanistic properties of ion transporters have been well elucidated by biophysical methods. Meanwhile the understanding of their exact functions in the whole cell homeostasis is limited by the difficulty to monitor their activity in vivo. The development of biosensors to track subtle changes in intracellular parameters provides an invaluable key to tackle this challenging issue. Here, we adapted the use of a dual biosensor using guard cells as experimental model to visualize the impact on the cytosol of anion transport from intracellular compartments. To image the activity of AtCLCa, a vacuolar NO3-/H+ exchanger regulating stomata aperture in Arabidopsis thaliana, we expressed a genetically encoded biosensor, ClopHensor allowing monitoring the dynamics of cytosolic anion concentration and pH. We first show that ClopHensor is not only a Cl- but also a NO3- sensor. We were then able to unravel and quantify the variations of NO3- and pH in the cytosol. Our data show that AtCLCa activity modifies cytosolic pH and NO3-, demonstrating that the transport activity of a vacuolar exchanger has a profound impact on cytosolic homeostasis. We propose that a major function of this endomembrane transporter is to adjust cytosolic conditions to cellular needs. This opens a novel perspective on the function of intracellular transporters of the CLC family in eukaryotes: not only controlling the intra organelle lumen but also actively modifying cytosolic conditions.\n\nSignificanceIntracellular transporters are key actors in cell biological processes. Their disruption causes major physiological defects. The role of intracellular ion transporters is usually seen through an \"intra organelle\" lens, meanwhile their potential action on cytosolic ion homeostasis is still a black box. The case of a plant CLC is used as a model to uncover the missing link between the regulation of conditions inside the vacuole and inside the cytosol. The development of an original live imaging workflow to simultaneously measure pH and anion dynamics in the cytosol reveals the role of an Arabidopsis thaliana CLC, AtCLCa, in the modification of cytosolic pH. Our data highlight an unsuspected function of endomembrane transporters in the regulation of cytosolic pH.

plant biology↗

bioRxiv2018

Crustaceans as hosts of parasites throughout the Phanerozoic

The fossil record of crustaceans as hosts of parasites has yielded three confirmed associations: epicaridean isopod-induced swellings on Jurassic–Recent decapod crustaceans, feminization of Cretaceous and Miocene male crabs possibly caused by rhizocephalan barnacles, and presumed pentastomids on/in Silurian ostracods. Cestode platyhelminth hooks and swellings by entoniscid isopods may be recognized in the future. Relative to 2014, we report an increase of 41% to 124 fossil decapod species with epicaridean-induced swellings in the branchial chamber (ichnotaxon Kanthyloma crusta). Furthermore, using a Late Jurassic (Tithonian) decapod assemblage from Austria, we find (1) no correlation between genus abundance and prevalence of K. crusta, (2) host preference for some galatheoid taxa (as for a mid-Cretaceous assemblage from Spain), and (3) a larger median size of parasitized versus non-parasitized specimens for two selected species. The latter result may be caused by infestation throughout ontogeny rather than exclusively in juveniles and/or possible selection for the larger sex.View Full Text

paleontology↗