Physical properties of the cell wall of photoautotrophic suspension cells fromChenopodium rubrum L

Disposable Fluidic Devices of Bionanochannels for Enzymatic Monitoring and Energy Harvesting

Nature produces a plethora of nanochannels to carry out highly complex biological tasks in a sophisticated manner. There have been several studies to understand the characteristics of these channels; however, efforts to apply them for technological advancements are still scarce. Here, we have demonstrated that the fluidic channels of biomaterials can be harvested as nanofluidic devices to produce energy from enzymatic chemical reactions. The bionanochannel-based nanofluidic devices exhibit various nanofluidic phenomena like surface-charged-governed ionic conductivity and development of the transmembrane potential. The mobility of ions in the hydrated bionanochannels are found to be higher than that of bulk water. The cation-selective nature of the biochannels was also exploited to harvest a continuous supply of power up to 74 mW m^-2 for 3 h from the enzymatic decomposition of urea. The transmembrane potential across the biochannels was also explored for label-free electrical monitoring of the enzymatic reaction inside the biological medium. Electrical monitoring on the kinetics of urease at different reaction temperatures suggested that inside biological medium the reaction goes through a pathway of lower activation energy (31.1 kJ) than that in the bulk environment (34.1 kJ). Enzyme urease was found to be more sustainable in bionanochannels than in glass vials.

Possible effect from shear stress on maturation of somatic embryos of Norway spruce (Picea abies)

Somatic embryogenesis is the only method with the potential for industrial scale clonal propagation of conifers. Implementation of the method has so far been hampered by the extensive manual labor required for development of the somatic embryos into plants. The utilization of bioreactors is limited since the somatic embryos will not mature and germinate under liquid culture conditions. The negative effect on mature embryo yields from liquid culture conditions has been previously described. We have described the negative effects of shear stress on the development of early stage somatic embryos (proembryogenic masses; PEMs) at shear stresses of 0.086 and 0.14 N/m(2). In the present study, additional flow rates were studied to determine the effects of shear stress at lower rates resembling shear stress in a suspension culture flask. The results showed that shear stress at 0.009, 0.014, and 0.029 N/m(2) inhibited the PEM expansions comparing with the control group without shear stress. This study also provides validation for the cross-correlation method previously developed to show the effect of shear stress on early stage embryo suspensor cell formation and polarization. Furthermore, shear stress was shown to positively affect the uptake of water into the cells. The results indicate that the plasmolyzing effect from macromolecules added to liquid culture medium to stimulate maturation of the embryos are affected by liquid culture conditions and thus can affect the conversion of PEMs into mature somatic embryos.

The apoplast and its significance for plant mineral nutrition

It has only recently become apparent that the apoplast plays a major role in a diverse range of processes, including intercellular signalling, plant-microbe interactions and both water and nutrient transport. Broadly defined, the apoplast constitutes all compartments beyond the plasmalemma - the interfibrillar and intermicellar space of the cell walls, and the xylem, including its gas- and water-filled intercellular space - extending to the rhizoplane and cuticle of the outer plant surface. The physico-chemical properties of cell walls influence plant mineral nutrition, as nutrients do not simply pass through the apoplast to the plasmalemma but can also be adsorbed or fixed to cell-wall components. Here, current progress in understanding the significance of the apoplast in plant mineral nutrition is reviewed. The contribution of the root apoplast to short-distance transport and nutrient uptakes is examined particularly in relation to Na⁺ toxicity and Al³⁺ tolerance. The review extends to long-distance transport and the role of the apoplast as a habitat for microorganisms. In the leaf, the apoplast might have benefits over the vacuole as a site for short-term nutrient storage and solute exchange with the atmosphere. Contents Summary 167 I. Introduction 168 II. The properties of the apoplast and its implication for solute movement 168 1. The middle lamella 168 2. The primary wall 168 3. The secondary cell wall 169 III. The root apoplast - nutrient uptake and short-distance transport 170 IV. The apoplast as a compartment for long distance transport 174 V. The apoplast - habitat for microorganisms 175 VI. The apoplast of leaves - a compartment of storage and of reactions 177 1. Transport routes in the leaf apoplast 177 2. Methods of studying apoplastic solutes 177 3. Solute relations in the leaf apoplast 178 4. Concentration gradients in the leaf apoplast 179 5. Ion relations in the leaf apoplast and symptoms of deficiency and toxicity 179 6. Ion relations in the leaf apoplast - influence of nutrient supply 180 7. The leaf apoplast - compartment for transient ion storage 180 8. Ion fluxes between apoplast and symplast 181 9. Apoplastic ion balance 181 10. Leaf apoplast - interaction with the atmosphere 183 VII. Conclusions 183 Acknowledgements 183 References 183.

Cloning of a tobacco apoplasmic invertase inhibitor. Proof of function of the recombinant protein and expression analysis during plant development

Higher plants express several isoforms of vacuolar and cell wall invertases (CWI), some of which are inactivated by inhibitory proteins at certain stages of plant development. We have purified an apoplasmic inhibitor (INH) of tobacco (Nicotiana tabacum) CWI to homogeneity. Based on sequences from tryptic fragments, we have isolated a full-length INH-encoding cDNA clone (Nt-inh1) via a reverse transcriptase-polymerase chain reaction. Southern-blot analysis revealed that INH is encoded by a single- or low-copy gene. Comparison with expressed sequence tag clones from Arabidopsis thaliana and Citrus unshiu indicated the presence of Nt-inh1-related proteins in other plants. The recombinant Nt-inh1-encoded protein inhibits CWI from tobacco and Chenopodium rubrum suspension-cultured cells and vacuolar invertase from tomato (Lycopersicon esculentum) fruit, whereas yeast invertase is not affected. However, only in the homologous system is the inhibition modulated by the concentration of Suc as previously shown for INH isolated from tobacco cells. Highly specific binding of INH to CWI could be shown by affinity chromatography of a total cell wall protein fraction on immobilized recombinant Nt-inh1 protein. RNA-blot analysis of relative transcript ratios for Nt-inh1 and CWI in different parts of adult tobacco plants revealed that the expression of both proteins is not always coordinate.

Chromatography on cells and biomolecular assemblies

Red cells, biomembrane vesicles, proteoliposomes and liposomes non-covalently immobilized in gel particles or beads have been used as stationary phases for biomembrane affinity analyses and ion-exchange chromatographic separation. Lipid monolayers coupled to silica beads have been utilized for membrane protein purification in detergent solution and plant cell walls for group separation of macromolecules according to size and charge. Further methodological studies are essential to implement general practical application.

Substrate specifity of the hexose carrier in the plasmalemma of Chenopodium suspension cells probed by transmembrane exchange diffusion

Substrate specifity of the proton-driven hexose cotransport carrier in the plasmalemma of photoautotrophic suspension cells of Chenopodium rubrum L. has been studies through the short-term perturbation of (14)C-labelled efflux of 3-O-methyl-D-glucose. Efflux, occurring exclusively via carrier-mediated exchange diffusion, is trans-stimulated by the substrate and trans-inhibited by the glucose-transport inhibitors phlorizin (K 1/2=7.9 mM) and its aglucon phloretin (K 1/2=84 μM); with both inhibitors, 3-O-methyl-D-glucose efflux may be blocked completely. Trans-stimulation of efflux (up to fourfold) by a variety of the D-enantiomers of neutral hexoses, including glucose (K 1/2=48 μM), 3-O-methyl-D-glucose (K 1/2=139 μM), and fructose (K 1/2=730 μM), but not by, for instance, D-allose, and L-sorbose, shows that carrier-substrate interaction critically involves the axial position at C-1 and C-3, respectively. We suggest that substrate binding by the Chenopodium hexose carrier involves both hydrophobic interaction with the pyran-ring and hydrogen-ion bonding at C-1 and C-3 of the D-glucose conformation.