Global genome expression analysis of rice in response to drought and high-salinity stresses in shoot, flag leaf, and panicle

To elucidate genome-level responses to drought and high-salinity stress in rice, a 70mer oligomer microarray covering 36,926 unique genes or gene models was used to profile genome expression changes in rice shoot, flag leaf and panicle under drought or high-salinity conditions. While patterns of gene expression in response to drought or high-salinity stress within a particular organ type showed significant overlap, comparison of expression profiles among different organs showed largely organ-specific patterns of regulation. Moreover, both stresses appear to alter the expression patterns of a significant number of genes involved in transcription and cell signaling in a largely organ-specific manner. The promoter regions of genes induced by both stresses or induced by one stress in more than one organ types possess relative enrichment of two cis-elements (ABRE core and DRE core) known to be associated with water stress. An initial computational analysis indicated that novel promoter motifs are present in the promoters of genes involved in rehydration after drought. This analysis suggested that rice might possess a mechanism that actively detects rehydration and facilitates rapid recovery. Overall, our data supports a notion that organ-specific gene regulation in response to the two abiotic stresses may primarily be mediated by organ-specific transcription responses. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11103-006-9111-1) contains supplementary material, which is available to authorized users

Effect of VEGF on Inflammatory Regulation, Neural Survival, and Functional Improvement in Rats following a Complete Spinal Cord Transection

After complete transection of the thoracic spinal segment, neonatal rats exhibit spontaneous locomotor recovery of hindlimbs, but this recovery is not found in adult rats after similar injury. The potential mechanism related to the difference in recovery of neonatal and adult rats remains unknown. In this study, 342 animals were analyzed. The vascular endothelial growth factor (VEGF) level in spinal segments below injury sites was significantly higher in postnatal day 1 rats (P1) compared with 28-day-old adult rats (P28) following a complete T9 transection. VEGF administration in P28 rats with T9 transection significantly improved the functional recovery; by contrast, treatment with VEGF receptor inhibitors in P1 rats with T9 transection slowed down the spontaneous functional recovery. Results showed more neurons reduced in the lumbar spinal cord and worse local neural network reorganization below injury sites in P28 rats than those in P1 rats. Transynaptic tracing with pseudorabies virus and double immunofluorescence analysis indicated that VEGF treatment in P28 rats alleviated the reduced number of neurons and improved their network reorganization. VEGF inhibition in neonates resulted in high neuronal death rate and deteriorated network reorganization. In in vivo studies, T9 transection induced less increase in the number of microglia in the spinal cord in P1 animals than P28 animals. VEGF treatment reduced the increase in microglial cells in P28 animals. VEGF administration in cultured spinal motoneurons prevented lipopolysaccharide (LPS)-induced neuronal death and facilitated neurite growth. Western blots of the samples of lumbar spinal cord after spinal transection and cultured spinal motoneurons showed a lower level of Erk1/2 phosphorylation after the injury or LPS induction compared with that in the control. The phosphorylation level increased after VEGF treatment. In conclusion, VEGF is a critical mediator involved in functional recovery after spinal transection and can be considered a potential target for clinical therapy

Assembly Pathway Selection of Designer Self-Assembling Peptide and Fabrication of Hierarchical Scaffolds for Neural Regeneration

The self-assembling peptide (SAP) RADA 16-I has been modified with various functional motifs to improve its performances in biomedical applications. Nevertheless, the assembly mechanisms of designer functional RADA 16-I SAPs (F-SAPs) have not been clearly illustrated. The main problem is the difficulty in preparing a completely molecular aqueous solution of F-SAP. In the current study, we demonstrated that different procedures for preparing the F-SAP solution could result in the formation of different conformations and consequently micro/macroscopic morphologies. F-SAP was molecularly dissolved in an appropriate solvent, such as hexafluoroisopropanol (HFIP), as evidenced by random coil conformation characterized by circular dichroism spectroscopy and morphologies under transmission electron microscopy. The monomers were induced into monolayers when the F-SAP solution in HFIP was adsorbed on mica as observed by atomic force microscopy. However, nanoscaled filaments containing β-sheets dominated in the F-SAP aqueous solution, in which case water acted as a poor solvent of F-SAP. Furthermore, the results of molecular dynamics simulation implicated that water facilitated F-SAP aggregation, whereas HFIP inhibited it. The β-sheet assemblies formed in water exhibited a high kinetic stability and did not disassemble rapidly after the addition of HFIP. Our study indicated that selecting the right assembly pathway of F-SAP required for targeted functions, for example, delivery of hydrophobic drugs in aqueous conditions, could be achieved by optimizing the preparation protocol in addition to molecular design. Moreover, hierarchical scaffolds mimicking the natural extracellular matrix could be fabricated by the direct electrospinning of F-SAP molecular solution in HFIP and biodegradable polymer for applications in neural regeneration by promoting neural differentiation, neurite outgrowth, and synapse formation