ORCID Profile
0000-0001-6544-9210
Current Organisations
Ghent University
,
University of Adelaide
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Publisher: Elsevier BV
Date: 10-2019
Publisher: MDPI AG
Date: 04-2021
DOI: 10.3390/JMSE9040375
Abstract: Oceanic islands harbor unique yet fragile marine ecosystems that require evidence-based environmental management. Among these islands, the Galapagos archipelago is well known for its fish ersity, but the factors that structure communities within and between its islands remain poorly understood. In this study, water quality, physical habitats and geographical distance were assessed as potential predictors for the ersity and structure of fish assemblages. Differences in the structure of fish assemblages of the two studied islands (Santa Cruz and Floreana) were most likely driven by temperature and nutrient concentrations. In the relatively highly populated island Santa Cruz, the structure of fish assemblages was more affected by water conditions than physical habitats while the contrary was true for the more pristine area of Floreana. A wide variety of species with different geographical origins were distributed over the different islands, which indicates that most fish species are able to reach the islands of the archipelago. However, temperature gradients and elevated nutrient levels cause large differences in the structure of local fish assemblages. In addition, in Santa Cruz nutrient concentrations were negatively correlated with α ersity. Since pollution is a clear pressure on the fish assemblages of oceanic islands, environmental management of the coastal areas is of paramount importance.
Publisher: Wiley
Date: 18-10-2016
DOI: 10.1111/PCE.12832
Abstract: The aquaporin AtPIP2 is an abundant plasma membrane intrinsic protein in Arabidopsis thaliana that is implicated in stomatal closure, and is highly expressed in plasma membranes of root epidermal cells. When expressed in Xenopus laevis oocytes, AtPIP2 increased water permeability and induced a non-selective cation conductance mainly associated with Na
Publisher: MDPI AG
Date: 03-11-2017
DOI: 10.3390/IJMS18112323
Publisher: MDPI AG
Date: 27-09-2020
DOI: 10.3390/IJMS21197135
Abstract: Some plasma membrane intrinsic protein (PIP) aquaporins can facilitate ion transport. Here we report that one of the 12 barley PIPs (PIP1 and PIP2) tested, HvPIP2 , facilitated cation transport when expressed in Xenopus laevis oocytes. HvPIP2 -associated ion currents were detected with Na+ and K+, but not Cs+, Rb+, or Li+, and was inhibited by Ba2+, Ca2+, and Cd2+ and to a lesser extent Mg2+, which also interacted with Ca2+. Currents were reduced in the presence of K+, Cs+, Rb+, or Li+ relative to Na+ alone. Five HvPIP1 isoforms co-expressed with HvPIP2 inhibited the ion conductance relative to HvPIP2 alone but HvPIP1 and HvPIP1 with HvPIP2 maintained the ion conductance at a lower level. HvPIP2 water permeability was similar to that of a C-terminal phosphorylation mimic mutant HvPIP2 S285D, but HvPIP2 S285D showed a negative linear correlation between water permeability and ion conductance that was modified by a kinase inhibitor treatment. HvPIP2 transcript abundance increased in barley shoot tissues following salt treatments in a salt-tolerant cultivar Haruna-Nijo, but not in salt-sensitive I743. There is potential for HvPIP2 to be involved in barley salt-stress responses, and HvPIP2 could facilitate both water and Na+/K+ transport activity, depending on the phosphorylation status.
Publisher: eLife Sciences Publications, Ltd
Date: 21-03-2017
DOI: 10.7554/ELIFE.23361
Abstract: Organelle-nuclear retrograde signaling regulates gene expression, but its roles in specialized cells and integration with hormonal signaling remain enigmatic. Here we show that the SAL1-PAP (3′-phosphoadenosine 5′- phosphate) retrograde pathway interacts with abscisic acid (ABA) signaling to regulate stomatal closure and seed germination in Arabidopsis. Genetically or exogenously manipulating PAP bypasses the canonical signaling components ABA Insensitive 1 (ABI1) and Open Stomata 1 (OST1) priming an alternative pathway that restores ABA-responsive gene expression, ROS bursts, ion channel function, stomatal closure and drought tolerance in ost1-2. PAP also inhibits wild type and abi1-1 seed germination by enhancing ABA sensitivity. PAP-XRN signaling interacts with ABA, ROS and Ca2+ up-regulating multiple ABA signaling components, including lowly-expressed Calcium Dependent Protein Kinases (CDPKs) capable of activating the anion channel SLAC1. Thus, PAP exhibits many secondary messenger attributes and exemplifies how retrograde signals can have broader roles in hormone signaling, allowing chloroplasts to fine-tune physiological responses.
Publisher: Oxford University Press (OUP)
Date: 16-09-2015
DOI: 10.1104/PP.15.00499
Publisher: Frontiers Media SA
Date: 19-01-2023
DOI: 10.3389/FPLS.2023.1078220
Abstract: Engineering membrane transporters to achieve desired functionality is reliant on availability of experimental data informing structure-function relationships and intelligent design. Plant aquaporin (AQP) isoforms are capable of transporting erse substrates such as signaling molecules, nutrients, metalloids, and gases, as well as water. AQPs can act as multifunctional channels and their transport function is reliant on many factors, with few studies having assessed transport function of specific isoforms for multiple substrates. High-throughput yeast assays were developed to screen for transport function of plant AQPs, providing a platform for fast data generation and cataloguing of substrate transport profiles. We applied our high-throughput growth-based yeast assays to screen all 13 Arabidopsis PIPs (AtPIPs) for transport of water and several neutral solutes: hydrogen peroxide (H2O2), boric acid (BA), and urea. Sodium (Na+) transport was assessed using elemental analysis techniques. All AtPIPs facilitated water and H2O2 transport, although their growth phenotypes varied, and none were candidates for urea transport. For BA and Na+ transport, AtPIP2 and AtPIP2 were the top candidates, with yeast expressing these isoforms having the most pronounced toxicity response to BA exposure and accumulating the highest amounts of Na+. Linking putative AtPIP isoform substrate transport profiles with phylogenetics and gene expression data, enabled us to align possible substrate preferences with known and hypothesized biological roles of AtPIPs. This testing framework enables efficient cataloguing of putative transport functionality of erse AQPs at a scale that can help accelerate our understanding of AQP biology through big data approaches (e.g. association studies). The principles of the in idual assays could be further adapted to test additional substrates. Data generated from this framework could inform future testing of AQP physiological roles, and address knowledge gaps in structure-function relationships to improve engineering efforts.
Publisher: Cold Spring Harbor Laboratory
Date: 10-05-2021
DOI: 10.1101/2021.05.09.443061
Abstract: Plant aquaporins have many more functions than just transporting water. Within the ersity of plant aquaporins are isoforms capable of transporting signaling molecules, nutrients, metalloids and gases. It is established that aquaporin substrate discrimination depends on combinations of factors such as solute size, pore size and polarity, and post-translational protein modifications. But our understanding of the relationships between variation in aquaporin structures and the implications for permeability is limited. High-throughput yeast-based assays were developed to assess erse substrate permeabilities to water, H 2 O 2 , boric acid, urea and Na + . All 13 plasma membrane intrinsic proteins (PIPs) from Arabidopsis (AtPIPs) were permeable to both water and H 2 O 2 , although their effectiveness varied, and none were permeable to urea. AtPIP2 isoforms were more permeable to water than AtPIP1s, while AtPIP1s were more efficient at transporting H 2 O 2 with AtPIP1 and AtPIP1 being the most permeable. Among the AtPIP2s, AtPIP2 and AtPIP2 were also permeable to boric acid and Na + . Linking AtPIP substrate profiles with phylogenetics and gene expression data enabled us to align substrate preferences with known biological roles of AtPIPs and importantly guide towards unidentified roles hidden by functional redundancy at key developmental stages and within tissue types. This analysis positions us to more strategically test in planta physiological roles of AtPIPs in order to unravel their complex contributions to the transport of important substrates, and secondly, to resolve links between aquaporin protein structure, substrate discrimination, and transport efficiency. Yeast based high throughput assays were developed to assess the permeability of each Arabidopsis PIP aquaporin isoform to water, H 2 O 2 , boric acid, urea and sodium.
Publisher: Wiley
Date: 14-08-2018
DOI: 10.1002/9781119312994.APR0626
Abstract: Rapid changes in soil salinity present plants with an osmotic stress. If the concentration of salt in the soil water is too high then water may flow from the plant roots back into the soil. As part of an adaptive response, the regulation of proteins associated with water transport, such as aquaporins, is altered. The change in regulation of aquaporins in roots in response to salt treatments occurs at transcriptional and post‐translational levels. Cell specific changes in aquaporin transcript levels, protein abundance, subcellular localisation, protein phosphorylation, and protein:protein interactions have been observed. It has recently been revealed that a subset of plant aquaporins can function both as water and as ion channels. Both Arabidopsis PIP2 and PIP2 function as water and ion channels in heterologous systems. AtPIP2 and AtPIP2 ionic conductance was carried by sodium (Na + ), indicating that a subset of plant PIP2s could have a role in Na + transport in plants. We show quantitatively how AtPIP2 may account for the calcium (Ca 2+ ) and pH sensitive Arabidopsis root non‐selective cation channel. Salt treatments are known to result in a change in AtPIP2 phosphorylation, and in Arabidopsis roots this is associated with internalisation of AtPIP2 into pre‐vacuolar compartments. Here we review how the regulation of aquaporins, in particular PIP2s, changes in root tissues in response to salt treatments.
Publisher: Oxford University Press (OUP)
Date: 23-06-2016
DOI: 10.1093/JXB/ERW237
Abstract: Salinity tolerance is correlated with shoot chloride (Cl–) exclusion in multiple crops, but the molecular mechanisms of long-distance Cl– transport are poorly defined. Here, we characterize the in planta role of AtSLAH1 (a homologue of the slow type anion channel-associated 1 (SLAC1)). This protein, localized to the plasma membrane of root stelar cells, has its expression reduced by salt or ABA, which are key predictions for a protein involved with loading Cl– into the root xylem. Artificial microRNA knockdown mutants of AtSLAH1 had significantly reduced shoot Cl− accumulation when grown under low Cl–, whereas shoot Cl– increased and the shoot nitrate/chloride ratio decreased following AtSLAH1 constitutive or stelar-specific overexpression when grown in high Cl–. In both sets of overexpression lines a significant reduction in shoot biomass over the null segregants was observed under high Cl– supply, but not low Cl– supply. Further in planta data showed AtSLAH3 overexpression increased the shoot nitrate/chloride ratio, consistent with AtSLAH3 favouring nitrate transport. Heterologous expression of AtSLAH1 in Xenopus laevis oocytes led to no detectible transport, suggesting the need for post-translational modifications for AtSLAH1 to be active. Our in planta data are consistent with AtSLAH1 having a role in controlling root-to-shoot Cl– transport.
Publisher: Frontiers Media SA
Date: 23-06-2017
Publisher: Oxford University Press (OUP)
Date: 28-02-2020
DOI: 10.1093/JXB/ERZ555
Abstract: Seeds are the typical dispersal and propagation units of angiosperms and gymnosperms. Water movement into and out of seeds plays a crucial role from the point of fertilization through to imbibition and seed germination. A class of membrane intrinsic proteins called aquaporins (AQPs) assist with the movement of water and other solutes within seeds. These highly erse and abundant proteins are associated with different processes in the development, longevity, imbibition, and germination of seed. However, there are many AQPs encoded in a plant’s genome and it is not yet clear how, when, or which AQPs are involved in critical stages of seed biology. Here we review the literature to examine the evidence for AQP involvement in seeds and analyse Arabidopsis seed-related transcriptomic data to assess which AQPs are likely to be important in seed water relations and explore additional roles for AQPs in seed biology.
Publisher: Wiley
Date: 07-2018
DOI: 10.1111/GEB.12729
Publisher: Oxford University Press (OUP)
Date: 11-12-2015
DOI: 10.1104/PP.15.01163
Publisher: Cold Spring Harbor Laboratory
Date: 24-01-2020
DOI: 10.1101/2020.01.21.909887
Abstract: Improving salinity tolerance in the most widely cultivated cereal, bread wheat ( Triticum aestivum L.), is essential to increase grain yields on saline agricultural lands. A Portuguese landrace, Mocho de Espiga Branca accumulates up to 6 folds greater leaf and sheath sodium (Na + ) than two Australian cultivars, Gladius and Scout, under salt stress. Despite high leaf and sheath Na + concentrations, Mocho de Espiga Branca maintained similar salinity tolerance compared to Gladius and Scout. A naturally occurring single nucleotide substitution was identified in the gene encoding a major Na + transporter TaHKT1 -D in Mocho de Espiga Branca, which resulted in a L190P amino acid residue variation. This variant prevents Mocho de Espiga Branca from retrieving Na + from the root xylem leading to a high shoot Na + concentration. The identification of the tissue tolerant Mocho de Espiga Branca will accelerate the development of more elite salt tolerant bread wheat cultivars.
Publisher: Springer Science and Business Media LLC
Date: 22-05-2020
DOI: 10.1038/S42003-020-0990-5
Abstract: During plant growth, sodium (Na + ) in the soil is transported via the xylem from the root to the shoot. While excess Na + is toxic to most plants, non-toxic concentrations have been shown to improve crop yields under certain conditions, such as when soil K + is low. We quantified grain Na + across a barley genome-wide association study panel grown under non-saline conditions and identified variants of a Class 1 HIGH-AFFINITY-POTASSIUM-TRANSPORTER ( HvHKT1 )-encoding gene responsible for Na + content variation under these conditions. A leucine to proline substitution at position 189 (L189P) in HvHKT1 disturbs its characteristic plasma membrane localisation and disrupts Na + transport. Under low and moderate soil Na + , genotypes containing HvHKT1:5 P189 accumulate high concentrations of Na + but exhibit no evidence of toxicity. As the frequency of HvHKT1:5 P189 increases significantly in cultivated European germplasm, we cautiously speculate that this non-functional variant may enhance yield potential in non-saline environments, possibly by offsetting limitations of low available K + .
No related grants have been discovered for Tom Moens.