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Glutamate, one of the major neurotransmitters in the central nervous system, is released into the synaptic spaces and bound to the glutamate receptors which facilitate normal synaptic transmission, synaptic plasticity, and brain development. Past studies have shown that glutamate with high concentration is a potent neurotoxin capable of destroying neurons through many signal pathways. In this research, our main purpose was to determine whether the specific soluble guanylyl cyclase activator YC-1 (3-(5′-hydroxymethyl-2′-furyl)-1-benzyl indazole) had effect on glutamate-induced apoptosis in cultured PC12 cells. The differentiated PC12 cells impaired by glutamate were used as the cell model of excitability, and were exposed to YC-1 or/and ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one) with gradient concentrations for 24 h. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl) assay was used to detect the cellular viability. Radioimmunoassay (RIA) was used to detect the cGMP (cyclic guanosine monophosphate) concentrations in PC12 cells. Hoechst 33258 staining and flow cytometric analysis were used to detect the cell apoptosis. The cellular viability was decreased and the apoptotic rate was increased when PC12 cells were treated with glutamate. Cells treated with YC-1 or/and ODQ showed no significant differences in the cell viability and intracellular cGMP levels compared with those of control group. The specific soluble guanylyl cyclase (sGC) inhibitor ODQ showed an inhibitory effect on cGMP level and aggravated the apoptosis of PC12 cells induced by glutamate. YC-1 elevated cGMP level thus decreased PC12 cell apoptosis induced by glutamate, but this effect could be reversed by ODQ. These results revealed that YC-1 might attenuate glutamate-induced PC12 cell apoptosis via a sGC-cGMP involved pathway. [ABSTRACT FROM AUTHOR]

metallothionein-like gene, ThMT3, encoding a type 3 metallothionein, was isolated from a Tamarix hispida leaf cDNA library. Expression analysis revealed that mRNA of ThMT3 was upregulated by high salinity as well as by heavy metal ions, and that ThMT3 was predominantly expressed in the leaf. Transgenic yeast ( Saccharomyces cerevisiae) expressing ThMT3 showed increased tolerance to Cd, Zn, Cu, and NaCl stress. Transgenic yeast also accumulated more Cd, Zn, and NaCl, but not Cu. Analysis of the expression of four genes ( GLR1, GTT2, GSH1, and YCF1) that aid in transporting heavy metal (Cd) from the cytoplasm to the vacuole demonstrated that none of these genes were induced under Cd, Zn, Cu, and NaCl stress in ThMT3-transgenic yeast. HO levels in transgenic yeast under such stress conditions were less than half those in control yeast under the same conditions. Three antioxidant genes ( SOD1, CAT1, and GPX1) were specifically expressed under Cd, Zn, Cu, and NaCl stress in the transgenic yeast. Cd, Zn, and Cu increased the expression levels of SOD1, CAT1, and GPX1, respectively, whereas NaCl induced the expression of SOD1 and GPX1. [ABSTRACT FROM AUTHOR]

Plant vacuolar H-ATPase (V-ATPase) plays an important role in response to different adverse environmental conditions. In the present study, we cloned and characterized a V-ATPase c subunit gene ( ThVHAc1) from Tamarix hispida. The deduced ThVHAc1 amino acid sequence lacks a signal peptide and ThVHAc1 is a highly hydrophobic protein with four transmembrane regions. A transient expression assay showed that the ThVHAc1-GFP fusion protein is expressed on onion epidermal endomembrane cells. Real-time RT-PCR demonstrated that ThVHAc1 gene expression was induced by NaCl, NaHCO, PEG and CdCl stress in T. hispida roots, stems and leaves. Exogenous application of abscisic acid (ABA) also stimulated ThVHAc1 transcript levels in the absence of stress, suggesting that ThVHAc1 is involved in ABA-dependent stress signaling pathway. Furthermore, the transgenic yeast expressing ThVHAc1 increased salt, drought, ultraviolet (UV), oxidative, heavy metal, cold and high temperature tolerance. Our results suggested that the ThVHAc1 gene from T. hispida serves a stress tolerance role in the species. [ABSTRACT FROM AUTHOR]

Cloning and identification of genes from the cambium of woody plants are important steps in the investigation of wood formation. In order to clone and identify the genes involved in wood formation, a cDNA library was constructed from the cambial tissue of Betula platyphylla Suk (birch). From the cDNA library, 2,878 high-quality ESTs were generated, representing 1,540 tentative unique genes (TUGs). Approximately 70% of the ESTs were matched to proteins in the NR database in GenBank and were grouped into 12 functional categories according to their functional annotation. Fifty TUGs potentially involved in wood formation, including the process of lignin biosynthesis, cell wall structure, cell wall polysaccharides synthesis or development regulation, were identified from the EST collection. The time course expression analysis of 13 wood formation related genes was further studied using RNA gel blot and semi-quantitative RT-PCR. The results showed that these genes were primarily expressed in tissue that was collected during two time periods, spring (26 April to 11 June) and later summer (30 July to 18 Sept). The bimodal expression curve of the genes indicates that both of these time periods are critical in wood formation in birch, and may be associated with cell wall expansion earlier in the year, and cell wall strengthening later in the year. [ABSTRACT FROM AUTHOR]

Plant peroxidases (PODs) have been ascribed a variety of biological functions, including hydrogen peroxide detoxification, lignin biosynthesis, hormonal signaling, and stress response. In the present study, ten POD genes, including three ascorbate peroxidases (class I PODs) and seven secretory peroxidases (class III PODs), were cloned from Tamarix hispida. The roles of the ten POD genes were addressed under different abiotic stress conditions, and gene expression profiles in roots, stems, and leaves were evaluated using real-time quantitative reverse-transcribed polymerase chain reaction. Our results showed that the relative abundance of the PODs was markedly different in roots, stems, and leaves, indicating that POD activity differs in these three organs. ThPOD1 and ThPOD8 were the most and least abundant, respectively, in all organs. The expression profiles in response to abiotic stresses were organ specific. All of the genes were highly induced by drought, salt, salt–alkaline, CdCl2, and abscisic acid (ABA) treatments in at least one organ. Five ThPOD genes were induced in roots, stems, and leaves under all of the studied stress conditions, indicating that they are closely associated with abiotic stress. Our results demonstrate that the ten plant peroxidases are all expressed in leaves, stems, and roots, that they are involved in different abiotic stress responses, and that they are controlled by an ABA-dependent stress signaling pathway. [ABSTRACT FROM AUTHOR]

Limonium bicolor, a halophytic species of flowering plant, thrives in saline-alkali soil, demonstrating that it has developed an efficient saline-alkali resistance system and has potential utility as a source of genetic determinants for saline-alkali tolerance. In this study, complementary DNA microarrays containing 1,240 clones of L. bicolor were constructed to have a better view of transcript expression in L. bicolor during saline-alkali (NaHCO3)-induced stress. We obtained transcript profiles of L. bicolor in response to NaHCO3 for 6, 24, and 48 h. A total of 149 transcripts were differentially regulated at least once under the conditions studied. Among these, at least six different patterns of transcript regulation could be distinguished. There were 111, 45, and 51 transcripts that were differentially regulated by NaHCO3 stress for 6, 24, and 48 h, respectively. Of these, nearly 35% were putative novel or functionally unknown genes, and the remainders were involved in a variety of functional areas such as defense, transport, metabolism, and transcription regulation. The microarray analysis demonstrated the complexity of, and differences in, gene expression patterns resulting from different NaHCO3 stress times. This study provides informative preliminary data and a starting point for more in-depth analyses of saline-alkali tolerance in L. bicolor. [ABSTRACT FROM AUTHOR]

Abstract   Tamarix hispida, a woody halophyte, thrives in saline and saline-alkali soil. To better understand the gene expression profiles that manifest in response to saline-alkali stress, three cDNA libraries were constructed from leaf tissue of T. hispida plants that were well watered and exposed to NaHCO3 for 24 and 52 h. A total of 9,447 high quality expressed sequence tags (ESTs) were obtained from the three libraries. These ESTs represent 3,945 unigenes, including 986 contigs and 2,959 singlets. The numbers of unigenes obtained from the three libraries were 1,752, 1,558 and 1,675, respectively. The EST analysis was performed to compare gene expression in the three cDNA libraries; the transcripts responsive to NaHCO3 were identified. The differentially expressed transcripts were identified. The up-regulation genes were involved in a variety function areas, such as stress-related proteins, hormone signaling transduction, antioxidative response, transcriptional regulators, protein synthesis and destination, ion homeostasis, photosynthesis and metabolism. The results indicated that the response to NaHCO3 in T. hispida is a complex one, involving multiple physiological and metabolic pathways. Nine gene expression patterns were compared in response to NaHCO3 and NaCl using real time reverse transcription-polymerase chain reaction (RT-PCR). Gene expression trends were similar after a 24-h exposure to either NaCl or NaHCO3, however, great variability was found after a 52-h exposure, indicating that short-term responses to either salt may not be obviously different. [ABSTRACT FROM AUTHOR]

Porous stainless steel with regular spherical particles were fabricated by spark plasma sintering (SPS) and compared with those obtained by conventional hot pressing (HP). The effects of the parameters during sintering processes on properties, such as porosity and compressive strength, were investigated. Microstructure studies showed that the regular spherical stainless steel particle could form porous ingots with regular pores in the way of close sphere package. Results indicated that the compressive properties of the SPS samples were superior to those of the HP samples. The study on relative diffusion coefficient in SPS and HP specimens indicated that SPS enhanced neck growth and accelerated the atom diffusion. Porous metals could be superfastly prepared by SPS under the conditions of higher heating rate, shorter holding time and lower sintering temperature. [ABSTRACT FROM AUTHOR]

The temperature field during the whole process of SPS sintering TiB2-BN sample was numerically simulated based on the simplification of the temperature rising process. The result shows that the highest temperature is found in the punch and the heat flows from punch to sample and die in SPS sintering system. In the radial direction, the center temperature of the sample is much higher than the circumference temperature of the sample. In the axial direction, the center temperature of the sample is lower than the border temperature of the sample. The temperature difference in the sample is growing bigger in the sintering process and reaches the maximum at the end of the heating-up process. [ABSTRACT FROM AUTHOR]

The article studies the fabrication of transparent aluminum nitride (AlN) ceramics by spark plasma sintering (SPS). A list of the properties of the AlN powder is provided. The authors have observed the fracture surface microstructure of the sintered AlN ceramics. They conclude that the rapid fabrication of transparent AlN ceramics confirmed the efficiency of SPS technique.