Expression of the Grifola frondosa Trehalose Synthase Gene and Improvement of Drought-Tolerance in Sugarcane （Saccharum officinarum L.）

Trehalose Is a nonreduclng dlsaccharlde of glucose that functions as a protectant In the stabilization of blologlcal structures and enhances stress tolerance to abiotic stresses in organisms. We report here the expression of a Grlfola frondosa trehalose synthase （TSase） gene for Improving drought tolerance In sugarcane （Saccharum offlclnarum L.）. The expression of the transgene was under the control of two tandem copies of the CaMV35S promoter and transferred Into sugarcane by Agrobacterium tumefaciens EHA105. The transgenlc plants accumulated high levels of trehalose, up to 8.805-12.863 mg/g fresh weight, whereas It was present at undetectable level in nontransgenlc plants. It has been reported that transgenlc plants transformed with Escherlchla coil TPS （trehalose-6-phosphatesynthase） and/or TPP （trehalose-6-phosphate phosphatase） are severely stunted and have root morphologlc alterations. Interestingly, our transgenlc sugarcane plants had no obvious morphological changes and no growth Inhibition in the field. Trehalose accumulation in 35S-35S：TSase plants resulted In In- creased drought tolerance, as shown by the drought and the drought physiological Indexes, such as the rate of bound water/free water, plasma membrane permeability, malondlaldehyde content, chlorophyll a and b contents, and activity of SOD and POD of the excised leaves. These results suggest that transgenlc plants transformed with the TSase gene can accumulate high levels of trehalose and have enhanced tolerance to drought.

Synthesis and Characterization of Sulfonated Polyphosphazene-graft-Polystyrene Copolymers for Proton Exchange Membranes

A novel series of polyphosphazene-grafl-polystyrene （PP-g-PS） copolymers were successfully prepared by atom transfer radical polymerization （ATRP） of styrene monomers and brominated poly（bis（4-methylphenoxy）phosphazene） macroinitiator. The graft density and the graft length could be regulated by changing the bromination degree of the macroinitiator and the ATRP reaction time, respectively. The PP-g-PS copolymers readily underwent a regioselective sulfonation reaction, which occurred preferentially at the polystyrene sites, producing the sulfonated PP-g-PS copolymers with a range of ion exchange capacities. The resulting sulfonated PP-g-PS membranes prepared by solution casting showed high water uptake, low water swelling and considerable proton conductivity. They also exhibited good oxidative stability and high resistance to methanol crossover. Morphological studies of the membranes by transmission electron microscopy showed clear nanophase-separated structures resulted from hydrophobic polyphosphazene backbone and hydrophilic polystyrene sulfonic acid segments, indicating the formation of proton transferring tunnels. Therefore, these sulfonated copolymers may be candidate materials for proton exchange membranes in direct methanol fuel cell （DMFC） applications.

Suppression of astrocytic autophagy by αB-crystallin contributes to α-synuclein inclusion formation

Background:Parkinson’s disease(PD)is characterized by a chronic loss of dopaminergic neurons and the presence of proteinaceous inclusions(Lewy bodies)within some remaining neurons in the substantia nigra.Recently,astroglial inclusion body has also been found in some neurodegenerative diseases including PD.However,the underlying molecular mechanisms of how astroglial protein aggregation forms remain largely unknown.Here,we investigated the contribution ofαB-crystallin(CRYAB),a small heat shock protein,inα-synuclein inclusion formation in astrocytes.Methods:Small interfering RNA(siRNA)-mediated CRYAB(siCRYAB)knockdown or CRYAB overexpression was performed to investigate the impact of CRYAB on the autophagy in human glioblastoma cell line U251 cells.Coimmunoprecipitation(co-IP)and immunoblotting were used to dissect the interaction among multiple proteins.The clearance ofα-synuclein in vitro was evaluated by immunocytochemistry.CRYAB transgenic mice and transgenic mice overexpressing A30P mutant form of humanα-synuclein were used to examine the influence of CRYAB toα-synuclein accumulation in vivo.Results:We found that knockdown of CRYAB in U251 cells or primary cultured astrocytes resulted in a marked augmentation of autophagy activity.In contrast,exogenous CRYAB disrupted the assembly of the BAG3-HSPB8-HSC70 complex via binding with BAG3,thereby suppressing the autophagy activity.Furthermore,CRYAB-regulated autophagy has relevance to PD pathogenesis.Knockdown of CRYAB remarkably promoted cytoplasmic clearance ofα-synuclein preformed fibrils(PFFs).Conversely,selective overexpression of CRYAB in astrocytes markedly suppressed autophagy leading to the accumulation of α-synuclein aggregates in the brain of transgenic mice expressing humanα-synuclein A30P mutant.Conclusions:This study reveals a novel function for CRYAB as a natural inhibitor of astrocytic autophagy and shows that knockdown of CYRAB may provide a therapeutic target against proteinopathies such as synucleinopathies.