Root vacuolar sequestration and suberization are prominent responses of Pistacia spp. rootstocks during salinity stress

Understanding the mechanisms of stress tolerance in diverse species is needed to enhance crop performance under conditions such as high salinity. Plant roots, in particular in grafted agricultural crops, can function as a boundary against external stresses in order to maintain plant fitness. However, limited information exists for salinity stress responses of woody species and their rootstocks. Pistachio (Pistacia spp.) is a tree nut crop with relatively high salinity tolerance as well as high genetic heterogeneity. In this study, we used a microscopy-based approach to investigate the cellular and structural responses to salinity stress in the roots of two pistachio rootstocks, Pistacia integerrima (PGI) and a hybrid, P. atlantica x P. integerrima (UCB1). We analyzed root sections via fluorescence microscopy across a developmental gradient, defined by xylem development, for sodium localization and for cellular barrier differentiation via suberin deposition. Our cumulative data suggest that the salinity response in pistachio rootstock species is associated with both vacuolar sodium ion (Na+) sequestration in the root cortex and increased suberin deposition at apoplastic barriers. Furthermore, both vacuolar sequestration and suberin deposition correlate with the root developmental gradient. We observed a higher rate of Na+ vacuolar sequestration and reduced salt-induced leaf damage in UCB1 when compared to P. integerrima. In addition, UCB1 displayed higher basal levels of suberization, in both the exodermis and endodermis, compared to P. integerrima. This difference was enhanced after salinity stress. These cellular characteristics are phenotypes that can be taken into account during screening for sodium-mediated salinity tolerance in woody plant species

Report and preliminary results of SONNE cruise SO175, Miami - Bremerhaven, 12.11 - 30.12.2003 : (GAP, Gibraltar Arc Processes)

Expedition SO175 using FS Sonne aimed for a multidisciplinerary geoscientific approach with an international group of researchers. Methods covered the entire span from geophysical data acquisition (seafloor mapping, echography, seismic reflection), sediment coring at sites of active fluid venting, in situ heat flow measurements across the entire length of the Gibraltar thrust wedge, the deformation front, landslide bodies, and mud volcanoes, and finally the deployment of a long-term pore pressure probe. Video-supported operations helped to identify fluid vent sites, regions with tectonic activity, and other attractive high priority targets. Qualitative and quantitative examinations took place on board and are continued on land with respect to pore pressure variation, geomicrobiology, sediment- and fluid mobilization, geochemical processes, faunal assemblages (e.g. cold water corals), and gas hydrates (flammable methane-ice-crystals). Main focus of the expedition has been a better understanding of interaction between dynamic processes in a seismically active region region with slow plate convergence. In the context of earthquake nucleation and subduction zone processes, the SO175 research programme had a variety of goals, such as: • To test the frictional behaviour of the abyssal plain sediments. • To explore the temperature field of the 1755 thrust earthquake event via heat flow measurements. • To assess the role of fluid venting and gas hydrate processes control slope stability and mud volcanic activity along the Iberian continental margin. • To measure isotope geochemistry of pore waters and carbonates of deep fluids. • To quantify microbial activity in Gibraltar wedge sediments. • To test whether microseismicity in the area corresponds to in situ pore pressure changes. • To find out if enhanced heat flow max be indicative of active subduction. Initial tentative results during the cruise suggest that there is a component of active thrusting at the base of the wedge, as attested by heat flow data. Based on mostly geochemical evidence, mud volcanism was found less active than previously assumed. Highlights from post-cruise research include the successful deployment of the long-term station and high frictional resistance of all incoming sediment on the three abyssal plains

Surface Plasmon Resonance for Human Bone Marrow Cells Imaging

Surface plasmon resonance imaging (SPRI) detects the changes in refractive index in close proximity to the surface of a thin metal film as variations in light intensity reflected from the back of the film and thus does not require labeling for visualization of the structures under investigation. While traditionally, the wave vector scanning is performed via angular rotations, the wave vector can also be scanned though tuning of the wavelength. Here we demonstrate that a combination of a non-monochromatic electrically tunable bandpass filter in conjunction with highly chromatically corrected imaging objectives can yield subcellular resolution for imaging of the interior refractive index of human mesenchymal stem cells

Smart structures for sensing environmental pollution

We present a novel composite sensing agent consisting of calix[4]resorcinarene (C[4]RA) and the conducting polyorthomethoxyaniline (POMA) and propose different sensing mechanisms that can take advantage of its nanoporosity and unique complexation reactions. The two main purposes of combining the materials are, to improve the deposition of the materials as Langmuir-Blodgett (LB) films and to create a nanoporous material that improves on the absorbtion / desorbtion behaviour of the films giving higher gas diffusion coefficients. LB films offer the highest control of film properties in comparison to alternative deposition methods and the inclusion of flexible calixarene in the polymer structure offers enhanced response and recovery times in comparison to straight chain molecules than steric acid. Further effects such as conductivity increases of the material of up to two orders of magnitude upon exposure to saturated vapours are also described. The results of the present studies are encouraging and promise potential for extended studies with alternative composites utilising different electroactive conjugated polymers and varying crown size calixarenes, but using the same deposition method

Kinetic studies of BTEX vapour adsorption onto surfaces of calix-4-resorcinarene films

The exposure of spun films of an amphiphilic calix-4-resorcinarene (C-4-RA) derivative to vapours of benzene, toluene, ethylbenzene, and m-xylene (BTEX) has produced a graded response, promising for the development of multisensor arrays. Fast and reversible adsorption of ethylbenzene was associated with changing the refractive index of the sensing layer and is believed to be due to the host-guest interaction between the cavitand C-4-RA molecules and the vapour molecules. Prolonged irradiation of the films with a focused laser beam has resulted in an initial increase of film sensitivity to the different organic vapours. (C) 2001 Elsevier Science B.V. All rights reserved

Endosidin 7 specifically arrests late cytokinesis and inhibits callose biosynthesis, revealing distinct trafficking events during cell plate maturation

Although cytokinesis is vital for plant growth and development, our mechanistic understanding of the highly regulated membrane and cargo transport mechanisms in relation to polysaccharide deposition during this process is limited. Here, we present an in-depth characterization of the small molecule endosidin 7 (ES7) inhibiting callose synthase activity and arresting late cytokinesis both in vitro and in vivo in Arabidopsis (Arabidopsis thaliana). ES7 is a specific inhibitor for plant callose deposition during cytokinesis that does not affect endomembrane trafficking during interphase or cytoskeletal organization. The specificity of ES7 was demonstrated (1) by comparing its action with that of known inhibitors such as caffeine, flufenacet, and concanamycin A and (2) across kingdoms with a comparison in yeast. The interplay between cell plate-specific post-Golgi vesicle traffic and callose accumulation was analyzed using ES7, and it revealed unique and temporal contributions of secretory and endosomal vesicles in cell plate maturation. While RABA2A-labeled vesicles, which accumulate at the early stage of cell plate formation, were not affected by ES7, KNOLLE was differentially altered by the small molecule. In addition, the presence of clathrin-coated vesicles in cells containing elevated levels of callose and their reduction under ES7 treatment further support the role of endocytic membrane remodeling in the maturing cell plate while the plate is stabilized by callose. Taken together, these data show the essential role of callose during the late stages of cell plate maturation and establish the temporal relationship between vesicles and regulatory proteins at the cell plate assembly matrix during polysaccharide deposition.E. Park, S.M. Díaz-Moreno, D.J. Davis, T.E. Wilkop, V. Bulone and G. Drakakak

Electrical characterisation of LB films containing US nanoparticles

CdS nanoparticles were formed within LB films of either Cd salts of stearic acid (SA) or calix[8]arene (CA) by exposing the samples to H2S gas. A series of DC and AC electrical measurements were performed for both planar and sandwich structures over a wide range of frequencies. Exponential behaviour of the DC I-V characteristics of the sandwich structures is typical for electron tunnelling through multilayered LB films. The conductivity value decreases after formation of CdS nanoparticles in the film, which is believed to be caused by the reduced layer-by-layer film order. AC measurements show a traditional insulating behaviour for all kind of films studied. Formation of CdS clusters in the LB films resulted in the decrease in both the capacitance and AC conductivity, which can be interpreted by the drop in the polarisability in disordered LB films. (C) 2002 Elsevier Science B.V. All rights reserved

Impedance analysis of the thickness shear mode resonator for organic vapour sensing

The impedance analysis of thickness shear mode (TSM) resonator coated with calixarene films was successfully exploited for the registration of organic solvent vapours of relatively high (pre-explosive) concentrations. The impedance analysis consisted of fitting the experimental admittance spectra of TSM resonators to the equivalent circuit model using a highly accurate and reliable least squares algorithm. This approach allowed simultaneous monitoring of the changes in mass and viscoelastic properties of the sensitive membrane caused by adsorption of organic vapours and therefore enables both quantification and discrimination between the vapours of different types of organic solvents, such as hexane and toluene. (C) 2003 Elsevier B.V. All rights reserved