Tobacco aquaporin NtAQP1 and human aquaporin hAQP1 contribute to single cell photosynthesis in Synechococcus.

Background Information: Aquaporins are HO-permeable membrane protein pores. However, some aquaporins are also permeable to other substances such as CO. In higher plants, overexpression of such aquaporins has already led to an enhanced photosynthetic performance due to improved CO mesophyll conductance.

Impacts of Radio-Frequency Electromagnetic Field (RF-EMF) on Lettuce ()-Evidence for RF-EMF Interference with Plant Stress Responses.

The increased use of wireless technology causes a significant exposure increase for all living organisms to radio frequency electromagnetic fields (RF-EMF). This comprises bacteria, animals, and also plants. Unfortunately, our understanding of how RF-EMF influences plants and plant physiology remains inadequate.

Metabolic engineering of ketocarotenoids biosynthetic pathway in Chlamydomonas reinhardtii strain CC-4102.

In Chlamydomonas reinhardtii, ketocarotenoid biosynthesis is limited to the diploid zygospore stage. In this study, we attempted to engineer the ketocarotenoid pathway into Chlamydomonas haploid vegetative green cells by overexpressing the key enzyme ß-carotene ketolase (CrBKT). We chose strain CC-4102 for the approach; competitive pathways, α-carotene biosynthesis and xanthophyll cycle are silenced in this strain.

Co-Translational Insertion of Aquaporins into Liposome for Functional Analysis via an Based Cell-Free Protein Synthesis System.

Aquaporins are important and well-studied water channel membrane proteins. However, being membrane proteins, sample preparation for functional analysis is tedious and time-consuming. In this paper, we report a new approach for the co-translational insertion of two aquaporins from and using the CFPS system.

Aquaporin PIP2;1 affects water transport and root growth in rice (Oryza sativa L.).

Aquaporins are key proteins in regulating water transport, plant growth and development. In this study, we investigated the function of plasma membrane intrinsic proteins (PIPs) in both yeast (Saccharomyces cerevisiae) and rice (Oryza sativa cv. Nipponbare).

Transcriptome analysis of the aquaporin AtPIP1;2 deficient line in Arabidopsis thaliana.

Atmospheric CO2 impacts all aspects of plant development. It has changed in the past and is predicted to change further on. Studies on the response of crop plants to low and elevated CO2 concerning growth, productivity and physiological processes are intense.

RNAi-mediated downregulation of poplar plasma membrane intrinsic proteins (PIPs) changes plasma membrane proteome composition and affects leaf physiology.

Plasma membrane intrinsic proteins (PIPs) are one subfamily of aquaporins that mediate the transmembrane transport of water. To reveal their function in poplar, we generated transgenic poplar plants in which the translation of PIP genes was downregulated by RNA interference investigated these plants with a comprehensive leaf plasma membrane proteome and physiome analysis. First, inhibition of PIP synthesis strongly altered the leaf plasma membrane protein composition.

T-DNA insertion in aquaporin gene AtPIP1;2 generates transcription profiles reminiscent of a low CO2 response.

Results from CO2 diffusion studies and characterization of Arabidopsis thaliana aquaporin AtPIP1;2 T-DNA insertion lines support the idea that specific aquaporins facilitate the diffusion of CO2 through biological membranes. However, their function as CO2 diffusion facilitators in plant physiology is still a matter of debate. Assuming that a lack of AtPIP1;2 causes a characteristic transcriptional response, we compared data from a AtPIP1;2 T-DNA insertion line obtained by Illumina sequencing, Affymetrix chip analysis and quantitative RT-PCR to the transcriptome of plants grown under drought stress or under low CO2 conditions.

The enhanced drought tolerance of rice plants under ammonium is related to aquaporin (AQP).

Previously, we demonstrated that drought resistance in rice seedlings was increased by ammonium (NH4(+)) treatment, but not by nitrate (NO3(-)) treatment, and that the change was associated with root development. To study the effects of different forms of nitrogen on water uptake and root growth under drought conditions, we subjected two rice cultivars (cv. 'Shanyou 63' hybrid indica and cv.

A refined model of water and CO₂ membrane diffusion: effects and contribution of sterols and proteins.

Black lipid bilayers, a general model system for biomembranes were studied for diffusion rates of small molecules such as water or CO2 using advanced analysis techniques and cell free synthesized proteins. We provide evidence that by simple insertion of proteins or sterols the diffusion rates of water or those of CO2 decrease. Insertion of cell free synthesized water permeable aquaporins restored water diffusion rates as well as insertion of CO2-facilitating aquaporins the CO2 diffusion.

Expression and characterization of plasma membrane aquaporins in stomatal complexes of Zea mays.

Stomata, the microscopic pores on the surface of the aerial parts of plants, are bordered by two specialized cells, known as guard cells, which control the stomatal aperture according to endogenous and environmental signals. Like most movements occurring in plants, the opening and closing of stomata are based on hydraulic forces. During opening, the activation of plasma membrane and tonoplast transporters results in solute accumulation in the guard cells.

Aquaporins and membrane diffusion of CO2 in living organisms.

Background: Determination of CO2 diffusion rates in living cells revealed inconsistencies with existing models about the mechanisms of membrane gas transport. Mainly, these discrepancies exist in the determined CO2 diffusion rates of bio-membranes, which were orders of magnitudes below those for pure lipid bilayers or theoretical considerations as well as in the observation that membrane insertion of specific aquaporins was rescuing high CO2 transport rates. This effect was confirmed by functional aquaporin protein analysis in heterologous expression systems as well as in bacteria, plants and partly in mammals.

Artificial environments for the co-translational stabilization of cell-free expressed proteins.

An approach for designing individual expression environments that reduce or prevent protein aggregation and precipitation is described. Inefficient folding of difficult proteins in unfavorable translation environments can cause significant losses of overexpressed proteins as precipitates or inclusion bodies. A number of chemical chaperones including alcohols, polyols, polyions or polymers are known to have positive effects on protein stability.

The grapevine root-specific aquaporin VvPIP2;4N controls root hydraulic conductance and leaf gas exchange under well-watered conditions but not under water stress.

We functionally characterized the grape (Vitis vinifera) VvPIP2;4N (for Plasma membrane Intrinsic Protein) aquaporin gene. Expression of VvPIP2;4N in Xenopus laevis oocytes increased their swelling rate 54-fold. Northern blot and quantitative reverse transcription-polymerase chain reaction analyses showed that VvPIP2;4N is the most expressed PIP2 gene in root.

Gas-tight triblock-copolymer membranes are converted to CO₂ permeable by insertion of plant aquaporins.

We demonstrate that membranes consisting of certain triblock-copolymers were tight for CO₂. Using a novel approach, we provide evidence for aquaporin facilitated CO₂ diffusion. Plant aquaporins obtained from heterologous expression were inserted into triblock copolymer membranes.

Molecular convergence of the parasitic plant species Cuscuta reflexa and Phelipanche aegyptiaca.

The parasitic plant species Cuscuta reflexa and Phelipanche aegyptiaca have independently developed parasitism, the former parasitizing on shoots and the latter attaching to roots. Regardless of these differences, the two species use similar organs, termed haustoria, to attach to the host plant. In this study, we show that this morphological similarity can be extended to the molecular level.

Mechanisms underlying CO2 diffusion in leaves.

Plants provide an excellent system to study CO(2) diffusion because, under light saturated conditions, photosynthesis is limited by CO(2) availability. Recent findings indicate that CO(2) diffusion in leaves can be variable in a short time range. Mesophyll CO(2) conductance could change independently from stomata movement or CO(2) fixing reactions and it was suggested that, beside others, the membranes are mesophyll CO(2) conductance limiting components.

The Arabidopsis aquaporin PIP1;2 rules cellular CO(2) uptake.

The membrane CO(2) flux into Arabidopsis mesophyll cells was studied using a scanning pH microelectrode. Arabidopsis thaliana mesophyll cells were exposed to photosynthesis-triggering light intensities, which induced cellular CO(2) uptake. Data obtained on a AtPIP1;2 T-DNA insertion line indicated that under these conditions, cellular CO(2) transport was not limited by unstirred layer effects but was dependent on the expression of the aquaporin AtPIP1;2.

The aquaporin TcAQP1 of the desert truffle Terfezia claveryi is a membrane pore for water and CO(2) transport.

Terfezia claveryi is a hypogeous mycorrhizal fungus belonging to the so-called "desert truffles," with a good record as an edible fungus and of considerable economic importance. T. claveryi improves the tolerance to water stress of the host plant Helianthemum almeriense, for which, in field conditions, symbiosis with T.

The Arabidopsis thaliana aquaporin AtPIP1;2 is a physiologically relevant CO₂ transport facilitator.

Cellular exchange of carbon dioxide (CO₂) is of extraordinary importance for life. Despite this significance, its molecular mechanisms are still unclear and a matter of controversy. In contrast to other living organisms, plants are physiologically limited by the availability of CO₂.

Significance of Cuscutain, a cysteine protease from Cuscuta reflexa, in host-parasite interactions.

Background: Plant infestation with parasitic weeds like Cuscuta reflexa induces morphological as well as biochemical changes in the host and the parasite. These modifications could be caused by a change in protein or gene activity. Using a comparative macroarray approach Cuscuta genes specifically upregulated at the host attachment site were identified.

Preparative scale production of functional mouse aquaporin 4 using different cell-free expression modes.

The continuous progress in the structural and functional characterization of aquaporins increasingly attracts attention to study their roles in certain mammalian diseases. Although several structures of aquaporins have already been solved by crystallization, the challenge of producing sufficient amounts of functional proteins still remains. CF (cell free) expression has emerged in recent times as a promising alternative option in order to synthesize large quantities of membrane proteins, and the focus of this report was to evaluate the potential of this technique for the production of eukaryotic aquaporins.

Calcium signaling during the plant-plant interaction of parasitic Cuscuta reflexa with its hosts.

The plant parasite Cuscuta reflexa induces various responses in compatible and incompatible host plants. The visual reactions of both types of host plants including obvious morphological changes require the recognition of Cuscuta ssp. A consequently initiated signaling cascade is triggered which leads to a tolerance of the infection or, in the case of some incompatible host plants, to resistance.

Aquaporin tetramer composition modifies the function of tobacco aquaporins.

Heterologous expression in yeast cells revealed that NtAQP1, a member of the so-called PIP1 aquaporin subfamily, did not display increased water transport activity in comparison with controls. Instead, an increased CO(2)-triggered intracellular acidification was observed. NtPIP2;1, which belongs to the PIP2 subfamily of plant aquaporins, behaved as a true aquaporin but lacked a CO(2)-related function.

Cuscuta reflexa invasion induces Ca release in its host.

Cuscuta reflexa induces a variety of reaction in its hosts. Some of these are visual reactions, and it is clear that these morphological changes are preceded by events at the molecular level, where signal transduction is one of the early processes. Calcium (Ca(2+)) release is the major second messenger during signal transduction, and we therefore studied Ca(2+) spiking in tomato during infection with C.