Phytohormone brassinosteroids (BRs) play critical roles in plant growth and development. BR acts by modulating the phosphorylation status of two key transcriptional factors, BRI1 EMS SUPPRESSOR1 and BRASSINAZOLE RESISTANT1 (BZR1), through the action of BRASSINOSTEROID INSENSITIVE1/BRI1 ASSOCIATED RECEPTOR KINASE1 receptors and a GSK3 kinase, BRASSINOSTEROID INSENSITIVE2 (BIN2). It is still unknown how the perception of BR at the plasma membrane connects to the expression of BR target genes in the nucleus. We show here that BZR1 functions as a nucleocytoplasmic shuttling protein and GSK3-like kinases induce the nuclear export of BZR1 by modulating BZR1 interaction with the 14-3-3 proteins. BR-activated phosphatase mediates rapid nuclear localization of BZR1. Besides the phosphorylation domain for 14-3-3 binding, another phosphorylation domain in BZR1 is required for the BIN2-induced nuclear export of BZR1. Mutations of putative phosphorylation sites in two distinct domains enhance the nuclear retention of BZR1 and BR responses in transgenic plants. We propose that the spatial redistribution of BZR1 is critical for proper BR signaling in plant growth and development.

The adverse effects of high salt on plants include Na ؉ toxicity and hyperosmotic and oxidative stresses. The plasma membrane-localized Na ؉ ͞H ؉ antiporter SOS1 functions in the extrusion of toxic Na ؉ from cells and is essential for plant salt tolerance. We report here that, under salt or oxidative stress, SOS1 interacts through its predicted cytoplasmic tail with RCD1, a regulator of oxidativestress responses. Without stress treatment, RCD1 is localized in the nucleus. Under high salt or oxidative stress, RCD1 is found not only in the nucleus but also in the cytoplasm. Like rcd1 mutants, sos1 mutant plants show an altered sensitivity to oxidative stresses. The rcd1mutation causes a decrease in salt tolerance and enhances the salt-stress sensitivity of sos1 mutant plants. Several genes related to oxidative-stress tolerance were found to be regulated by both RCD1 and SOS1. These results reveal a previously uncharacterized function of a plasma membrane Na ؉ ͞H ؉ antiporter in oxidativestress tolerance and shed light on the cross-talk between the ion-homeostasis and oxidative-stress detoxification pathways involved in plant salt tolerance.salt stress ͉ reactive oxygen species ͉ hydrogen peroxide stress

Multimodal imaging is highly desirable for accurate diagnosis because it can provide complementary information from each imaging modality. In this study, a sol-gel reaction of tantalum(V) ethoxide in a microemulsion containing Fe(3)O(4) nanoparticles (NPs) was used to synthesize multifunctional Fe(3)O(4)/TaO(x) core/shell NPs, which were biocompatible and exhibited a prolonged circulation time. When the NPs were intravenously injected, the tumor-associated vessel was observed using computed tomography (CT), and magnetic resonance imaging (MRI) revealed the high and low vascular regions of the tumor.

Net photosynthesis (Pn) is reversibly inhibited at moderately high temperature. To investigate this further, we examined the effects of heat stress on Arabidopsis plants in which Rubisco activase or thylakoid membrane fluidity has been modified. During heating leaves from 25 to 40 degrees C at 250 ppm CO2 and 1% O2, the wild-type (WT), plants expressing the 43 kDa isoform only (rwt43), and plants accumulating activase 40% of WT (R100) exhibited similar inhibitions in the Pn and Rubisco activation state. Despite better membrane integrity than WT, plants having less polyunsaturation of thylakoid lipids (fad7/8 double mutant) failed to maintain greater Pn than the WT. Plants expressing the 46 kDa isoform only (rwt46) exhibited the most inhibition, but plants expressing a 46 kDa isoform incapable of redox regulation (C411A) were similar to the WT. The null mutant (rca) exhibited a continuous decline in Pn. As measured by fluorescence, electron transport activity decreased concomitantly with Pn but PSII was not damaged. Following a quick recovery to 25 from 40 degrees C, whereas most lines recovered 90% Pn, the rwt46 and rca lines recovered only to 59 and <10%, respectively. As measured by NADP-malate dehydrogenase activation, after an initial increase at 30 degrees C, stromal oxidation in the WT and rwt46 plants did not increase further as Pn decreased. These results provide additional insight into the role of Rubisco activation and activase in the reversible heat inhibition of Pn.

Late embryogenesis abundant (LEA) proteins are members of a large group of hydrophilic, glycine-rich proteins found in plants, algae, fungi, and bacteria known collectively as hydrophilins that are preferentially expressed in response to dehydration or hyperosmotic stress. Group 2 LEA (dehydrins or responsive to abscisic acid) proteins are postulated to stabilize macromolecules against damage by freezing, dehydration, ionic, or osmotic stress. However, the structural and physicochemical properties of group 2 LEA proteins that account for such functions remain unknown. We have analyzed the structural properties of a recombinant form of a soybean (Glycine max) group 2 LEA (rGmDHN1). Differential scanning calorimetry of purified rGmDHN1 demonstrated that the protein does not display a cooperative unfolding transition upon heating. Ultraviolet absorption and circular dichroism spectroscopy revealed that the protein is in a largely hydrated and unstructured conformation in solution. However, ultraviolet absorption and circular dichroism measurements collected at different temperatures showed that the protein exists in equilibrium between two extended conformational states: unordered and left-handed extended helical or poly (l-proline)-type II structures. It is estimated that 27% of the residues of rGmDHN1 adopt or poly (l-proline)-type II-like helical conformation at 12°C. The content of extended helix gradually decreases to 15% as the temperature is increased to 80°C. Studies of the conformation of the protein in solution in the presence of liposomes, trifluoroethanol, and sodium dodecyl sulfate indicated that rGmDHN1 has a very low intrinsic ability to adopt ␣-helical structure and to interact with phospholipid bilayers through amphipathic ␣-helices. The ability of the protein to remain in a highly extended conformation at low temperatures could constitute the basis of the functional role of GmDHN1 in the prevention of freezing, desiccation, ionic, or osmotic stress-related damage to macromolecular structures. Group 2 LEA proteins or dehydrins or responsive to abscisic acid (RAB) proteins were originally identified as the "D-11" family of LEA proteins in developing cotton (Gossypium hirsutum) embryos (Baker et al., 1988;Dure et al., 1989;Hughes and Galau, 1989). Dehydrins appear to be ubiquitously expressed in gymnosperms (Jarvis et al., 1996;Richard et al., 2000) and angiosperms (Campbell and Close, 1997;Close, 1997). Immunological surveys have also detected dehydrin-related proteins in algae, yeast, and cyanobacteria (Close and Lammers, 1993; Campbell and Close, 1997;Close, 1997;Li et al., 1998;Mtwisha et al., 1998). Group 2 LEA proteins form a subset of evolutionarily conserved Gly-rich, hydrophilic proteins associated with adaptation to hyperosmotic conditions (Garay-Arroyo et al., 2000). Dehydrins are induced typically in maturing seeds or vegetative tissues following salinity, dehydration, cold, or freezing stress or abscisic acid (ABA) treatment (Close, 1996(Close, , 1997 Campbell and Close, 1997). Numero...

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Group 1 late embryogenesis-abundant (LEA) proteins are a subset of hydrophilins that are postulated to play important roles in protecting plant macromolecules from damage during freezing, desiccation, or osmotic stress. To better understand the putative functional roles of group 1 LEA proteins, we analyzed the structure of a group 1 LEA protein from soybean (Glycine max). Differential scanning calorimetry of the purified, recombinant protein demonstrated that the protein assumed a largely unstructured state in solution. In the presence of trifluoroethanol (50% [w/v]), the protein acquired a 30% ␣-helical content, indicating that the polypeptide is highly restricted to adopt ␣-helical structures. In the presence of sodium dodecyl sulfate (1% [w/v]), 8% of the polypeptide chain adopted an ␣-helical structure. However, incubation with phospholipids showed no effect on the protein structure. Ultraviolet absorption and circular dichroism spectroscopy revealed that the protein existed in equilibrium between two conformational states. Ultraviolet absorption spectroscopy studies also showed that the protein became more hydrated upon heating. Furthermore, circular dichroism spectral measurements indicated that a minimum of 14% of amino acid residues existed in a solvent-exposed, left-handed extended helical or poly (l-proline)-type (PII) conformation at 20°C with the remainder of the protein being unstructured. The content of PII-like structure increased as temperature was lowered. We hypothesize that by favoring the adoption of PII structure, instead of the formation of ␣-helical or ␤-sheet structures, group 1 LEA proteins retain a high content of surface area available for interaction with the solvent. This feature could constitute the basis of a potential role of LEA proteins in preventing freezing, desiccation, or osmotic stress damage.Late embryogenesis-abundant (LEA) proteins accumulate to high concentrations in plant embryos during the latter stages of seed development before desiccation (Baker et al., 1988;Dure et al., 1989;Hughes and Galau, 1989). LEA proteins also accumulate in vegetative tissues exposed to exogenous abscisic acid, as well as dehydration, osmotic, and lowtemperature stress (Chandler and Robertson, 1994;Ingram and Bartels, 1996; Bray, 1997; Close, 1996 Close, , 1997Thomashow, 1998; Nylander et al., 2001). More than seven different groups of LEA proteins have been described and categorized by virtue of similarities in their deduced amino acid sequences (Baker et al., 1988;Dure et al., 1989). The majority of LEA proteins are highly hydrophilic and display a preponderance (e.g. Ala, Gly, Glu, and Thr) or lack (e.g. Trp and Cys) of certain amino acid residues (Dure, 1993a(Dure, , 1993b(Dure, , 1997. Thus, LEA proteins are part of a larger, evolutionarily conserved group of hydrophilic proteins termed "hydrophilins" involved in various adaptive responses to hyperosmotic conditions (Garay-Arroyo et al., 2000).Various functions have been proposed for different groups of LEA proteins ranging from wa...

In this paper, we systematically investigate three different routes of synthesizing 2% Na-doped PbTe after melting the elements: (i) quenching followed by hot-pressing (QH), (ii) annealing followed by hot-pressing, and (iii) quenching and annealing followed by hot-pressing. We found that the thermoelectric figure of merit, zT, strongly depends on the synthesis condition and that its value can be enhanced to ∼2.0 at 773 K by optimizing the size distribution of the nanostructures in the material. Based on our theoretical analysis on both electron and thermal transport, this zT enhancement is attributed to the reduction of both the lattice and electronic thermal conductivities; the smallest sizes (2∼6 nm) of nanostructures in the QH sample are responsible for effectively scattering the wide range of phonon wavelengths to minimize the lattice thermal conductivity to ∼0.5 W/m K. The reduced electronic thermal conductivity associated with the suppressed electrical conductivity by nanostructures also helped reduce the total thermal conductivity. In addition to the high zT of the QH sample, the mechanical hardness is higher than the other samples by a factor of around 2 due to the smaller grain sizes. Overall, this paper suggests a guideline on how to achieve high zT and mechanical strength of a thermoelectric material by controlling nano-and microstructures of the material.waste heat recovery | energy harvesting A thermoelectric (TE) device is a solid-state device that converts heat directly into electricity and vice versa (1-5). As there are no moving parts involved and the device configuration is simple, TE devices have demonstrated long-term reliability in various space missions, usually running for tens of years without maintenance (6). However, they are not yet widely used in many other energy conversion applications on earth mainly due to their low conversion efficiencies. The conversion efficiency of a TE device largely depends on the material properties, i.e., the figure of merit (1, 3), zT = [S 2 /ρ(κ L + κ e )]T, where T is the absolute temperature, S is the Seebeck coefficient, ρ is the electrical resistivity, and κ L and κ e are, respectively, the lattice (or phonon) and electronic thermal conductivities. Increasing the zT has proven challenging because the constituent TE properties are interdependent; for example, decreasing the electrical resistivity results in decreasing the Seebeck coefficient and increasing the electronic thermal conductivity.