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  • 1
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 09 June 2015, Vol.112(23), pp.7309-14
    Description: The Darwin plant Dionaea muscipula is able to grow on mineral-poor soil, because it gains essential nutrients from captured animal prey. Given that no nutrients remain in the trap when it opens after the consumption of an animal meal, we here asked the question of how Dionaea sequesters prey-derived potassium. We show that prey capture triggers expression of a K(+) uptake system in the Venus flytrap. In search of K(+) transporters endowed with adequate properties for this role, we screened a Dionaea expressed sequence tag (EST) database and identified DmKT1 and DmHAK5 as candidates. On insect and touch hormone stimulation, the number of transcripts of these transporters increased in flytraps. After cRNA injection of K(+)-transporter genes into Xenopus oocytes, however, both putative K(+) transporters remained silent. Assuming that calcium sensor kinases are regulating Arabidopsis K(+) transporter 1 (AKT1), we coexpressed the putative K(+) transporters with a large set of kinases and identified the CBL9-CIPK23 pair as the major activating complex for both transporters in Dionaea K(+) uptake. DmKT1 was found to be a K(+)-selective channel of voltage-dependent high capacity and low affinity, whereas DmHAK5 was identified as the first, to our knowledge, proton-driven, high-affinity potassium transporter with weak selectivity. When the Venus flytrap is processing its prey, the gland cell membrane potential is maintained around -120 mV, and the apoplast is acidified to pH 3. These conditions in the green stomach formed by the closed flytrap allow DmKT1 and DmHAK5 to acquire prey-derived K(+), reducing its concentration from millimolar levels down to trace levels.
    Keywords: Akt ; Cipk ; Dionaea Muscipula ; Hak5 ; Transporter ; Calcium -- Metabolism ; Droseraceae -- Metabolism ; Potassium -- Metabolism ; Protein Kinases -- Metabolism
    ISSN: 00278424
    E-ISSN: 1091-6490
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  • 2
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States, May 14, 2013, Vol.110(20), p.8296(6)
    Description: The phytohormone abscisic acid (ABA) plays a key role in the plant response to drought stress. Hence, ABA-dependent gene transcription and ion transport is regulated by a variety of protein kinases and phosphatases. However, the nature of the membrane-delimited ABA signal transduction steps remains largely unknown. To gain insight into plasma membrane-bound ABA signaling, we identified sterol-dependent proteins associated with detergent resistant membranes from Arabidopsis thaliana mesophyll cells. Among those, we detected the central ABA signaling phosphatase ABI1 (abscisic-acid insensitive 1) and the calcium-dependent protein kinase 21 (CPK21). Using fluorescence microscopy, we found these proteins to Iocalize in membrane nanodomains, as observed by colocalization with the nanodomain marker remorin Arabidopsis thaliana remorin 1.3 (AtRem 1.3). After transient coexpression, CPK21 interacted with SLAH3 [slow anion channel I (SLAC1) homolog 3] and activated this anion channel. Upon CPK21 stimulation, SLAH3 exhibited the hallmark properties of S-type anion channels. Coexpression of SLAH3/CPK21 with ABI1, however, prevented proper nanodomain localization of the SLAH3/CPK21 protein complex, and as a result anion channel activation failed. FRET studies revealed enhanced interaction of SLAH3 and CPK21 within the plasma membrane in response to ABA and thus confirmed our initial observations. Interestingly, the ABA-induced SLAH3/CPK21 interaction was modulated by ABI1 and the ABA receptor RCAR1/PYL9 [regulatory components of ABA receptor 1/PYR1 (pyrabactin resistance 1)-like protein 9]. We therefore propose that ABA signaling via inhibition of ABI1 modulates the apparent association of a signaling and transport complex within membrane domains that is necessary for phosphorylation and activation of the S-type anion channel SLAH3 by CPK21. doi/10.1073/pnas.1211667110
    Keywords: Arabidopsis Thaliana -- Physiological Aspects ; Arabidopsis Thaliana -- Health Aspects ; Abscisic Acid -- Physiological Aspects ; Abscisic Acid -- Health Aspects ; Ion Channels -- Physiological Aspects ; Ion Channels -- Health Aspects ; Protein Kinases -- Physiological Aspects ; Protein Kinases -- Health Aspects
    ISSN: 0027-8424
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  • 3
    In: PLoS ONE, 2014, Vol.9(2)
    Description: Objectives and Aim This study was performed to analyse the effects of different sevoflurane concentrations on the incidence of epileptiform EEG activity during induction of anaesthesia in children in the clinical routine. Background It was suggested in the literature to use sevoflurane concentrations lower than 8% to avoid epileptiform activity during induction of anaesthesia in children. Methods 100 children (age: 4.6±3.0 years, ASA I–III, premedication with midazolam) were anaesthetized with 8% sevoflurane for 3 min or 6% sevoflurane for 5 min in 100% O 2 via face mask followed by 4% sevoflurane until propofol and remifentanil were given for intubation. EEGs were recorded continuously and were analysed visually with regard to epileptiform EEG patterns. Results From start of sevoflurane until propofol/remifentanil administration, 38 patients (76%) with 8% sevoflurane had epileptiform EEG patterns compared to 26 patients (52%) with 6% (p = 0.0106). Epileptiform potentials tended to appear later in the course of the induction with 6% than with 8%. Up to an endtidal concentration of 6% sevoflurane, the number of children with epileptiform potentials was similar in both groups (p = 0.3708). The cumulative number of children with epileptiform activity increased with increasing endtidal sevoflurane concentrations. The time from start of sevoflurane until loss of consciousness was similar in patients with 8% and 6% sevoflurane (42.2±17.5 s vs. 44.9 s ±14.0 s; p = 0.4073). An EEG stage of deep anaesthesia with continuous delta waves 〈2.0 Hz appeared significantly earlier in the 8% than in the 6% group (64.0±22.2 s vs. 77.9±20.0 s, p = 0.0022). Conclusion The own analysis and data from the literature show that lower endtidal concentrations of sevoflurane and shorter administration times can be used to reduce epileptiform activity during induction of sevoflurane anaesthesia in children.
    Keywords: Research Article ; Medicine
    E-ISSN: 1932-6203
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  • 4
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 14 May 2013, Vol.110(20), pp.8296-301
    Description: The phytohormone abscisic acid (ABA) plays a key role in the plant response to drought stress. Hence, ABA-dependent gene transcription and ion transport is regulated by a variety of protein kinases and phosphatases. However, the nature of the membrane-delimited ABA signal transduction steps remains largely unknown. To gain insight into plasma membrane-bound ABA signaling, we identified sterol-dependent proteins associated with detergent resistant membranes from Arabidopsis thaliana mesophyll cells. Among those, we detected the central ABA signaling phosphatase ABI1 (abscisic-acid insensitive 1) and the calcium-dependent protein kinase 21 (CPK21). Using fluorescence microscopy, we found these proteins to localize in membrane nanodomains, as observed by colocalization with the nanodomain marker remorin Arabidopsis thaliana remorin 1.3 (AtRem 1.3). After transient coexpression, CPK21 interacted with SLAH3 [slow anion channel 1 (SLAC1) homolog 3] and activated this anion channel. Upon CPK21 stimulation, SLAH3 exhibited the hallmark properties of S-type anion channels. Coexpression of SLAH3/CPK21 with ABI1, however, prevented proper nanodomain localization of the SLAH3/CPK21 protein complex, and as a result anion channel activation failed. FRET studies revealed enhanced interaction of SLAH3 and CPK21 within the plasma membrane in response to ABA and thus confirmed our initial observations. Interestingly, the ABA-induced SLAH3/CPK21 interaction was modulated by ABI1 and the ABA receptor RCAR1/PYL9 [regulatory components of ABA receptor 1/PYR1 (pyrabactin resistance 1)-like protein 9]. We therefore propose that ABA signaling via inhibition of ABI1 modulates the apparent association of a signaling and transport complex within membrane domains that is necessary for phosphorylation and activation of the S-type anion channel SLAH3 by CPK21.
    Keywords: Lipid Metabolism ; Abscisic Acid -- Metabolism ; Arabidopsis -- Metabolism ; Arabidopsis Proteins -- Metabolism ; Ion Channels -- Metabolism
    ISSN: 00278424
    E-ISSN: 1091-6490
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  • 5
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 02 May 2017, Vol.114(18), pp.4822-4827
    Description: The Venus flytrap captures insects and consumes their flesh. Prey contacting touch-sensitive hairs trigger traveling electrical waves. These action potentials (APs) cause rapid closure of the trap and activate secretory functions of glands, which cover its inner surface. Such prey-induced haptoelectric stimulation activates the touch hormone jasmonate (JA) signaling pathway, which initiates secretion of an acidic hydrolase mixture to decompose the victim and acquire the animal nutrients. Although postulated since Darwin's pioneering studies, these secretory events have not been recorded so far. Using advanced analytical and imaging techniques, such as vibrating ion-selective electrodes, carbon fiber amperometry, and magnetic resonance imaging, we monitored stimulus-coupled glandular secretion into the flytrap. Trigger-hair bending or direct application of JA caused a quantal release of oxidizable material from gland cells monitored as distinct amperometric spikes. Spikes reminiscent of exocytotic events in secretory animal cells progressively increased in frequency, reaching steady state 1 d after stimulation. Our data indicate that trigger-hair mechanical stimulation evokes APs. Gland cells translate APs into touch-inducible JA signaling that promotes the formation of secretory vesicles. Early vesicles loaded with H and Cl fuse with the plasma membrane, hyperacidifying the "green stomach"-like digestive organ, whereas subsequent ones carry hydrolases and nutrient transporters, together with a glutathione redox moiety, which is likely to act as the major detected compound in amperometry. Hence, when glands perceive the haptoelectrical stimulation, secretory vesicles are tailored to be released in a sequence that optimizes digestion of the captured animal.
    Keywords: Dionaea Muscipula ; Amperometry ; Exocytosis ; Plant Digestion ; Secretion ; Insecta ; Droseraceae -- Physiology ; Exocytosis -- Physiology ; Signal Transduction -- Physiology
    ISSN: 00278424
    E-ISSN: 1091-6490
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  • 6
    In: Journal of Plant Biochemistry & Physiology, 2015, Vol.3(3)
    ISSN: Journal of Plant Biochemistry & Physiology
    E-ISSN: 23299029
    Source: CrossRef
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  • 7
    In: New Phytologist, April 2017, Vol.214(2), pp.597-606
    Description: The present study was performed to elucidate the fate of carbon (C) and nitrogen (N) derived from protein of prey caught by carnivorous Dionaea muscipula. For this, traps were fed 13C/15N‐glutamine (Gln). The release of 13CO2 was continuously monitored by isotope ratio infrared spectrometry. After 46 h, the allocation of C and N label into different organs was determined and tissues were subjected to metabolome, proteome and transcriptome analyses. Nitrogen of Gln fed was already separated from its C skeleton in the decomposing fluid secreted by the traps. Most of the Gln‐C and Gln‐N recovered inside plants were localized in fed traps. Among nonfed organs, traps were a stronger sink for Gln‐C compared to Gln‐N, and roots were a stronger sink for Gln‐N compared to Gln‐C. A significant amount of the Gln‐C was respired as indicated by 13C‐CO2 emission, enhanced levels of metabolites of respiratory Gln degradation and increased abundance of proteins of respiratory processes. Transcription analyses revealed constitutive expression of enzymes involved in Gln metabolism in traps. It appears that prey not only provides building blocks of cellular constituents of carnivorous Dionaea muscipula, but also is used for energy generation by respiratory amino acid degradation.
    Keywords: Amino Acid Catabolism ; Carbon Partitioning ; Dionaea Muscipula Venus Flytrap ; Glutamine ; Nitrogen N Partitioning ; Plant Carnivory ; Respiratory Degradation
    ISSN: 0028-646X
    E-ISSN: 1469-8137
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  • 8
    Language: English
    In: Current Biology, 08 February 2016, Vol.26(3), pp.286-295
    Description: Carnivorous plants, such as the Venus flytrap ( ), depend on an animal diet when grown in nutrient-poor soils. When an insect visits the trap and tilts the mechanosensors on the inner surface, action potentials (APs) are fired. After a moving object elicits two APs, the trap snaps shut, encaging the victim. Panicking preys repeatedly touch the trigger hairs over the subsequent hours, leading to a hermetically closed trap, which via the gland-based endocrine system is flooded by a prey-decomposing acidic enzyme cocktail. Here, we asked the question as to how many times trigger hairs have to be stimulated (e.g., now many APs are required) for the flytrap to recognize an encaged object as potential food, thus making it worthwhile activating the glands. By applying a series of trigger-hair stimulations, we found that the touch hormone jasmonic acid (JA) signaling pathway is activated after the second stimulus, while more than three APs are required to trigger an expression of genes encoding prey-degrading hydrolases, and that this expression is proportional to the number of mechanical stimulations. A decomposing animal contains a sodium load, and we have found that these sodium ions enter the capture organ via glands. We identified a flytrap sodium channel DmHKT1 as responsible for this sodium acquisition, with the number of transcripts expressed being dependent on the number of mechano-electric stimulations. Hence, the number of APs a victim triggers while trying to break out of the trap identifies the moving prey as a struggling Na -rich animal and nutrition for the plant. Children are able to count at the age of 15–18 months. In this work, Böhm et al. demonstrate that the carnivorous Venus flytrap plant is able to count as well. The leaf tips develop into snap traps, where the number of contacts of the prey with mechano-sensitive trap initiates capturing and processing of the animal victim.
    Keywords: Biology
    ISSN: 0960-9822
    E-ISSN: 1879-0445
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  • 9
    Language: English
    In: Current Biology, 30 March 2015, Vol.25(7), pp.928-935
    Description: During the transition from water to land, plants had to cope with the loss of water through transpiration, the inevitable result of photosynthetic CO fixation on land [ ]. Control of transpiration became possible through the development of a new cell type: guard cells, which form stomata. In vascular plants, stomatal regulation is mediated by the stress hormone ABA, which triggers the opening of the SnR kinase OST1-activated anion channel SLAC1 [ ]. To understand the evolution of this regulatory circuit, we cloned both ABA-signaling elements, SLAC1 and OST1, from a charophyte alga, a liverwort, and a moss, and functionally analyzed the channel-kinase interactions. We were able to show that the emergence of stomata in the last common ancestor of mosses and vascular plants coincided with the origin of SLAC1-type channels capable of using the ancient ABA drought signaling kinase OST1 for regulation of stomatal closure. Fast drought/ABA-signaling in guard cells of higher plants involves the SnRK2 kinase OST1 activating the anion channel SLAC1. Here, Lind et al. show that during evolution of early land plants, SLAC1 co-opted the ancient ABA-signaling pathway by developing motifs at its cytosolic termini that allow ABA-activated OSTs to regulate SLAC1 activity.
    Keywords: Biology
    ISSN: 0960-9822
    E-ISSN: 1879-0445
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  • 10
    Language: English
    In: Current Biology, 09 September 2013, Vol.23(17), pp.1649-1657
    Description: Ammonium transporter (AMT/MEP/Rh) superfamily members mediate ammonium uptake and retrieval. This pivotal transport system is conserved among all living organisms. For plants, nitrogen represents a macronutrient available in the soil as ammonium, nitrate, and organic nitrogen compounds. Plants living on extremely nutrient-poor soils have developed a number of adaptation mechanisms, including a carnivorous lifestyle. This study addresses the molecular nature, function, and regulation of prey-derived ammonium uptake in the Venus flytrap, , one of the fastest active carnivores. The ammonium transporter DmAMT1 was localized in gland complexes where its expression was upregulated upon secretion. These clusters of cells decorating the inner trap surface are engaged in (1) secretion of an acidic digestive enzyme cocktail and (2) uptake of prey-derived nutrients. Voltage clamp of oocytes expressing DmAMT1 and membrane potential recordings with DmAMT1-expressing glands were used to monitor and compare electrophysiological properties of DmAMT1 in vitro and in planta. DmAMT1 exhibited the hallmark biophysical properties of a NH -selective channel. At depolarized membrane potentials (V  = 0), the K (3.2 ± 0.3 mM) indicated a low affinity of DmAMT1 for ammonium that increased systematically with negative going voltages. Upon hyperpolarization to, e.g., −200 mV, a K of 0.14 ± 0.015 mM documents the voltage-dependent shift of DmAMT1 into a NH transport system of high affinity. We suggest that regulation of glandular DmAMT1 and membrane potential readjustments of the endocrine cells provide for effective adaptation to varying, prey-derived ammonium sources.
    Keywords: Biology
    ISSN: 0960-9822
    E-ISSN: 1879-0445
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