Overexpression of phospholipase Dα gene enhances drought and salt tolerance of Populus tomentosa

The cDNA of AtPLDα (Arabidopsis thaliana Phospholipase Dα) gene was introduced into P. tomentosa (Populus tomentosa) under the control of the Cauliflower mosaic virus 35S promoter. Southern and Northern blot analyses suggested that the AtPLDα gene has been transferred into the P. tomentosa genome. No obvious morphological or developmental difference was observed between the transgenic and wild-type (WT) plants. Drought and salt tolerance and gene expression of seedlings of several transgenic lines and WT plants (control) were studied. The results showed that the rhizogenesis rate and the average root-length of transgenic lines were significantly higher than WT plants after mannitol and NaCl treatment under the same growth conditions. Northern blot analysis indicated that the higher the PLDα expression in the transgenic plants, the more tolerant the transgenic plants are to drought and salt treatment. Meanwhile, another group of these transgenic lines and WT plants (control) were treated with PEG6000 and NaCl separately. The contents of chlorophylls and the activities of some anti-oxidant enzymes (superoxide dismutase, guaiacol peroxidase and catalase) as well as malondialde-hyde and relative electrical conductivity were analyzed. Altogether, our results demonstrated that overexpression of the PLDα gene can enhance the drought and salt tolerance in transgenic P. tomen-tosa plants.     

Comparative expression analysis of three genes from the Arabidopsis vacuolar Na^＋/H^＋ antiporter （AtNHX） family in relation to abiotic stresses

Na~ /H~ antiporters (NHX) are ubiquitous transmembrane proteins that play a key role in salt tolerance of plants. In this study, the sequence of 3 Arabidopsis NHX gene (AtNHX2―4) were compared with other AtNHX members. Putative cis-elements analysis identified elements that have been associated with stress responses. The activities of the promoters AtNHX2―4 were studied in transgenic plants carrying corresponding promoter-β-glucuronidase (GUS) fusions. The AtNHX2 promoter-GUS analysis indicated that AtNHX2 was expressed in constitutive pattern with high GUS activity in roots and leaves. AtNHX2 promoter activity was not up-regulated by NaCl or abscisic acid (ABA), in contrast to the AtNHX1 promoter which was previously studied. The AtNHX3 and AtNHX4 promoters showed tissue-specific activities. Strong GUS activity was detected in roots and vascular bundles of the stele in plants carry-ing an AtNHX4 promoter-GUS fusion, and GUS activity increased under salt stress suggesting a func-tion related to salt tolerance. Transgenic plants carrying the AtNHX3 promoter-GUS fusion showed strong GUS activity in petals, stamens and tops of siliques, suggesting a possible role of AtNHX3 in flower and seed development. Results of histochemical analysis suggested that AtNHX2―4 are involved in divergent functions and are differentially regulated under abiotic stress. The structure of AtNHX4 was predicted to include 12 transmembrane regions and a NHX domain. Overexpression of AtNHX4 in Arabidopsis transgenic lines confers greater salt tolerance than in wild type plants. These results suggest that AtNHX4 may encode a putative vacuolar NHX that plays an important role in salt tolerance.     

Overexpression of phospholipase <Emphasis Type="Italic">D</Emphasis>α gene enhances drought and salt tolerance of <Emphasis Type="Italic">Populus tomentosa</Emphasis>

The cDNA of AtPLDa （Arabidopsis thaliana Phospholipase Da） gene was introduced into P. tomentosa （Populus tomentosa） under the control of the Cauliflower mosaic virus 35S promoter. Southern and Northern blot analyses suggested that the AtPLDa gene has been transferred into the P. tomentosa genome. No obvious morphological or developmental difference was observed between the transgenic and wild-type （WT） plants. Drought and salt tolerance and gene expression of seedlings of several transgenic lines and WT plants （control） were studied. The results showed that the rhizogenesis rate and the average root-length of transgenic lines were significantly higher than WT plants after mannitol and NaCI treatment under the same growth conditions. Northern blot analysis indicated that the higher the PLDa expression in the transgenic plants, the more tolerant the transgenic plants are to drought and salt treatment. Meanwhile, another group of these transgenic lines and WT plants （control） were treated with PEG6000 and NaCI separately. The contents of chlorophylls and the activities of some anti- oxidant enzymes （superoxide dismutase, guaiacol peroxidase and catalase） as well as malondialdehyde and relative electrical conductivity were analyzed. Altogether, our results demonstrated that overexpression of the PLDa gene can enhance the drought and salt tolerance in transgenic P. tomentosa plants.     

Over-expression of an Arabi-dopsisd δ-OAT gene enhances salt and drought tolerance in transgenic rice

δ-OAT, ornithine-δ-aminotransferase, is the key enzyme involved in proline biosynthesis. In this study the Arabidopsis δ-OAT gene was transferred into rice (Oryza sativa L. ssp japonica cv. Zhongzuo 321), whose successful integration was demonstrated by PCR and Southern blot analysis. The over-expression of the gene in transgenic rice was also confirmed. Biochemical analysis showed that, under salt or drought stress conditions, proline contents in the leaves and roots in transgenic rice plants were 5- to 15-fold of those in non-transgenic controls. Under stress conditions, germinating rate of transgenic lines is higher than that of controls. Although the growth of rice plants tested were more and more retarded with the increasing of NaCI concentration, the transgenic plants grow faster compared to the controls under the same stress condition. Meanwhile, the resistance to KCl and MgSO4 stresses was also found enhanced in transgenie rice. Furthermore, the over-expression of δ-OAT also improved the yield of transgenic plants under stress conditions. The average yield per plant of transgenic lines increases about 12%--41% more than that of control line sunder 0.1 mol/L NaCI stress. These data indicated that the over-expression of δ-OAT, with the accumulation of proline, resulted in the enhancement of salt and drought tolerance and an increase of rice yield, which is of significance in agriculture.     

Salt tolerance conferred by over-expression of OsNHX1 gene in Poplar 84K

OsNHX1 gene (Na^＋/H^＋ antiporter gene of Oryza sativa L.) was introduced into Poplar 84K with Agrobacterium tumefaciens-mediated transformation. PCR, Southern and Northern blot analysis showed that OsNHX1 gene was incorporated successfully into the genome of Poplar 84K and expressed in these transgenic plants. Salt tolerance test showed that three lines of transgenic plants grew normally in the presence of 2OO mmol/L NaCI, while the Na^＋ content in the leaves of the transgenic plants grown at 2OO mmol/L NaCl was significantly higher than that in plants grown at 0mmol/L NaCI. The osmotic potential in the transgenic plants with high salinity treatment was lower than that of control plants. Our results demonstrate the potential use of these transgenic plants for agricultural use in saline soils.     

Molecular characterization of GmNHX2, a Na＋/H＋ antiporter gene homolog from soybean,and its heterolosous expression to improve salt tolerance in Arabidopsis

Na＋/H＋ antiporters have been well documented to enhance plant salt tolerance by regulating cellular ion homeostasis. Here, a putative Na＋/H＋ antiporter gene homolog GmNHX2 from soybean was cloned and predicted to encode a protein of 534 amino acids with 10 putative transmembrane domains. GmNHX2 was expressed in all soybean plant tissues but enriched in roots and its expression was induced by NaCI and polyethylene glycol （PEG） treatments. GmNHX2 exhibits greater sequence similarity with LeNHX2 and AtNHX6 than that of AtNHX1 and AtSOS1. Although phylogenetic analysis clustered GmNHX2 with organellar （tonoplast and vesicles） antiporters, the GmNHX2-EGFP （enhanced green fluorescent protein） fusion protein was possibly localized in the plasma membrane or organelle membrane of transgenic plant cells, Furthermore, transgenic Arabidopsis plants expressing GmNHX2 were more tolerant to high NaCl concentrations during germination and seedling stages when compared with wild-type plants. These results suggest that GmNHX2 is a membrane Na＋/H＋ antiporter and may function to regulate ion homeostasis under salt stress.     

Introduction of AtNHX1 into beet improved salt-tolerance of transgenic plants

AtNHX1 gene encoding the Na ^＋/H ^＋ antiport on the vacuole membrane of Arabidopsis was transferred into small bud tips of 1-3mm in length derived from immature inflorescence cultures of six genotypes of beet （ Beta vulgaris L. ） by the infection of Agrobacterium tumefaciens and transgenic plants with improved salt-tolerance were obtained. When transgenic plants at 5-leaf stage were potted in sand and irrigated with solutions containing a range of concentrations of NaCl （171-513mM）, they showed minor symptoms of damage from salinity and better tolerance than the controls. There were considerable discrepancies of salt-tolerance between transgenic plants originated from the same genotype and also between different genotypes. After vernalization, bolting transgenic plants were enveloped with two layers of gauzes for self-pollination. T1 seedlings tolerant to 342-427mM NaCl were obtained respectively. These results revealed that it was feasible to improve salt-tolerance of beets by the introduction of AtNHX1 gene into cultured bud cells.     

Generating of rice OsCENH3-GFP transgenic plants and their genetic applications

In order to investigate rice functional centromeres, OsCENH3-GFP chimeric gene was constructed and transformed into the indica rice variety, Zhongxian 3037, mediated by Agrobacturium. The integration of the exogenous genes in the transgenic plants was confirmed by PCR and Southern blotting. The transgenic plants grow normally during their whole life time, just like Zhongxian 3037. No significant defects were detected in either mitosis or meiosis of the transgenic plants. The overlapping of GFP signals and anti-CENH3 foci in both mitotic and meiotic cells from T0 and T1 generation plants indicated that GFP had been successfully fused with CENH3, so the GFP signals can well represent the CENH3 locations on each chromosome. To evaluate the applicability of the transgenic plants to other genetic studies, fluorescence in situ hybridization （FISH） using rice centromeric tandem repetitive sequence CentO as the probe was conducted on the zygotene chromosomes of pollen mother cells （PMCs）. It has been revealed that the GFP signals are overlapping with CentO FISH signals, showing that CentO is one of the key elements constituting rice functional centromeres. Immunofluorescent staining using anti-o-tublin antibody and anti-PAIR2 antibody on the chromosomes during mitosis and meiosis stages of the transgenic plants further reveals that OsCENH3-GFP transgenic plants can be widely used for studying rice molecular biology, especially for tagging functional centromeres in both living cells and tissues.     

Developmental characteristics and response to iron toxicity of root border cells in rice seedlings

To investigate the Fe^2＋ effects on root tips in rice plant, experiments were carried out using border cells in vitro. The border cells were pre-planted in aeroponic culture and detached from root tips. Most border cells have a long elliptical shape. The number and the viability of border cells in situ reached the maxima of 1600 and 97.5%, respectively, at 20---25 mm root length. This mortality was more pronounced at the first 1-12 h exposure to 250 mg/L Fe^2＋ than at the last 12-36 h. After 36 h, the cell viability exposed to 250 mg/L Fe^2＋ decreased to nought, whereas it was 46.5% at 0 mg/L Fe^2＋. Increased Fe^2＋ dosage stimulated the death of detached border cells from rice cultivars. After 4 h Fe^2＋ treatment, the cell viabilities were _〉80% at 0 and 50 mg/L Fe^2＋ treatment and were 〈62% at 150, 250 and 350 mg/L Fe^2＋ treatment; The viability of border cells decreased by 10% when the Fe^2＋ concentration increased by 100 mg/L. After 24 h Fe^2＋ treatment, the viabilities of border cells at all the Fe^2＋ levels were 〈65%; The viability of border cells decreased by 20% when the Fee＋ concentration increased by 100 mg/L. The decreased viabilities of border cells indicated that Fe^2＋ dosage and treatment time would cause deadly effect on the border cells. The increased cell death could protect the root tips from toxic harm. Therefore, it may protect root from the damage caused by harmful iron toxicity.     

Effects of different types of palatal lateral excisions on growth and development of maxilla and dental arch

Objective： This study aimed to explore the effects of different types of palatal lateral excisions on the growth and development of the maxilla and dental arch, and to investigate the underlying mechanisms. Methods： A total of 112 3-week-old Sprague-Dawley （SD） male rats were randomly divided into a control and 3 experimental groups： the mucoperiosteal denudation group, the mucosal flap excision group, and the periosteum excision group. In the experimental groups, bilateral mucoperiosteal, mucosal flap and periosteum were excised respectively in the lateral one half of the palate. Four rats in each group were randomly chosen for sacrifice every two weeks. The maxilla was dissected following the excision. The widths of the maxilla and dental arch were measured and the histological phenomena were investigated at different phases. At the same time, 12 animals in each group were sequentially injected with calcein every two weeks. Three animals in each group, whose fluorescent labeling was used, were sacrificed for investigating bone formation at Week 8 following injection. Results： （1） Each experimental group presented the constriction of the maxilla and dental arch. The upper first molars in the experimental groups inclined medially. The mucoperiosteal denudation group showed the largest degree of effect followed by the periosteum excision group. The indices of the mucosal flap excision group, which retained the structures of the periosteum layer, had the most approximate values to the control group; （2） Different histological changes among the experimental groups were detected. The fibers penetrated into the palatal bone as Sharpey＇s fibers in the mucoperiosteal denudation group. The pattern of bone deposition was the bundle type. Sharpey＇s fibers were not found in the mucosal flap and periosteum excision groups and the depositions of palatal bone were the lamellar type as those in the control group; （3） The rates of bone deposition in the experimental groups decreased compared with the     

Weak interaction between CH3SO and HOCl: Hydrogen bond, chlorine bond and oxygen bond

B3lyp/6-311＋＋g＊＊ and mp2/6-311＋＋g＊＊ calculations were used to analyze the interaction between CH3SO and HOCl. Nine （complex A： S1A-S9A） and five （complex B： S4B-S7B and S10B） minima were localized on the potential energy surface of CH3SO…HOCl complexes at b3lyp/6-311＋＋g＊＊ and mp2/ 6-311＋＋g＊＊ computational levels, respectively. The AIM and NBO theories were also applied to explain the nature of the complexes. Bonding energy of complexes A and B corrected with BSSE falls in the ranges of -0.4―-41.4 kJ·mol-1 and -6.9―-35.8 kJ·mol-1 at mp2/6-311＋＋g＊＊ level, respectively. The re- sults show that a novel oxygen bond complex （S6） exists in the system, besides hydrogen bond and chlorine bond. Especially, S6B-F, S6B-Br and S7B are blue shifted complexes compared with red shifted S6A, because the electron transfer occurs between LP1（S8） and σ＊（O5-Cl7）, resulting in the increase of O5-Cl7 and the decrease of vibrational frequency. The complex of S10B has characteristics of both red shift and blue shift.     

Dehydration melting of UHP eclogite and paragneiss in the Dabie orogen: Evidence from laboratory experiment to natural observation

Dehydration melting of subducted continental crust is significant during exhumation, and its study from both experimental and petrological observations is of great importance to our understanding of continental geodynamics. Dehydration melting experi- ments were carried out on ultrahigh-pressure （UHP） eclogite from Bixiling in the Dabie orogen using a piston cylinder at 1.5-3.0 GPa and 800-950℃ to investigate partial melting of eclogite induced by phengite breakdown. The phengite-bearing eclogite started to melt at T≤800-850℃ and P=1.5-2.0 GPa and produced about 3% granitic melt. The products of dehydration melting vary with temperature and pressure. Such results provide valuable constraints on the micro-texture related to partial melting of UHP rocks in the Dabie-Sulu orogenic belt. Three types of polyphase inclusions were identified in garnet from the Shuanghe UHP eclogite. K-feldspar and quartz inclusions are interpreted to represent the products of segregation and crystallization of minor amounts of melt that formed during dehydration melting of phengite by the inferred reaction Phengite＋Omphacite＋Quartz Amphibole_＋Garnet＋Melt （K-feldspar＋Quartz＋Plagioclase）. Polyphase inclusions of phengite and K-feldspar＋Quartz inclusions were also found in zoisite/clinozoisite and garnet from the Shuanghe garnet-bearing paragneiss. These polyphase inclusions pro- vide evidence for a continuous process from sub-solidus dehydration to partial melting within the UHP gneissic rocks. The com- positional variation of garnets demonstrates that breakdown of epidote-group minerals may have played a crucial role during de- hydration melting reaction of phengite. The Ti-in-zircon thermometry and Si content of phengite in zircon suggest that partial melting would occur at 783-839℃ and 2.0-2.5 GPa. Therefore, both experimental results and petrological observations indicate that dehydration melting and fluid activity within the Dabie UHP rocks at micro-scale are controlled by the breakdown of phengite.     

Phytoremediation of heavy metal polluted soils and water: Progresses and perspectives

Environmental pollution affects the quality ofpedosphere, hydrosphere, atmosphere, lithosphere and biosphere. Great efforts have been made in the last two decades to reduce pollution sources and remedy the polluted soil and water resources. Phytoremediation, being more cost-effective and fewer side effects than physical and chemical approaches, has gained increasing popularity in both academic and practical circles. More than 400 plant species have been identified to have potential for soil and water remediation. Among them, Thlaspi, Brassica, Sedum alfredii H., and Arabidopsis species have been mostly studied. It is also expected that recent advances in biotechnology will play a promising role in the development of new hyperaccumulators by transferring metal hyperaccumulating genes from low biomass wild species to the higher biomass producing cultivated species in the times to come. This paper attempted to provide a brief review on recent progresses in research and practical applications of phytoremediation for soil and water resources.     

Hypothetical mode of action of earthworm extract with hepatoprotective and antioxidant properties

The hepatoprotective potential of earthworm extract （EE） （Lampito mauritii, Kinberg） was evaluated against paracetamol-induced liver injury in Wistar albino rat, in comparison with silymarin, the standard hepatoprotective drug. We observed a reduction in liver antioxidants, such as glutathione （GSH）, superoxide dismutase （SOD）, glutathione peroxidase （GPx）, and catalase （CAT） and in serum total protein, and an increase in serum alkaline phosphatase （ALP）, serum aspertate ami- notranferase （AST）, serum alanine aminotranferase （ALT）, bilirubin and liver thiobarbituric acid reactive substances （TBARS） due to liver injury in the paracetamol-administered rats （2 g/kg）. On the contrary, increased activities of liver GSH, SOD, GPx, CAT and serum total protein level, and decrease in the contents of serum ALP, AST, ALT, bilirubin and liver TBARS were observed in rats administered with different doses of EE （100, 200 and 300 mg/kg）, which are similar to the activities of hepato- protective drug silymarin （150 mg/kg）. The mode of action of EE as evidenced by the above parameters may suggest that EE, on the one hand, prevents the formation of the reactive oxygen groups, or scavenges these groups, thereby preventing the damage on the hepatic cells, and, on the other hand, modulates the genes responsible for synthesis of antioxidant enzymes such as GPx, CAT and SOD in liver tissue and decreases the serum enzymatic activities such as ALP, AST and ALT.     

热浸锌层人工加速腐蚀试验数值分析

按照Van-Hoff公式K_t=2~(■/10)确定人工加腐蚀系数;按照几何方程y=K_e·t~n+A和直线方程y=K_L·t+C在电子计算机上分别对土壤腐蚀和大气腐蚀的实验数据进行曲线拟合。对热浸锌层在腐蚀介质中的电化学过程的分析结果表明,上述数据处理及其结果与实际情形相符。     

An approach for QoS measurement and web service selection sureness

Web services have gained popularity m recent years anu prowue a new moue, u~ w~u, w,,,~,, ,~- cilitates interaction of scientific and business applications through the Internet. More often, several services with similar functionality are available from a large and changing number of service provid- ers. Quality of Service （QoS） is the dominant factor in service selection and is of great importance to users. In this paper, we propose a model for QoS measurement and web services selection. The model consists of QoS model, QoS monitoring, QoS comparison and service selection with a QoS feedback mechanism. The most suitable service is to take into account the agreed QoS, monitoring is done during invocation phase and if any deviation is recorded, next suitable service is selected. Fi- nally the model is proved to be feasible and effective by simulation experiments.     

Research and implementation ranging method based of continuous wave radar on tri-frequency

In the traditional dual-frequency radar ranging system, there is a contradiction between ranging precision and ranging distance. So a tri-frequency ranging method is proposed. The principle of the tri-frequency ranging is that the distance can be achieved by transmitting the three frequencies and then measuring the three phase difference and calculating the number of wavelength. What＇ s more, range ambiguity will not occur within a certain distance. The experimental results show that, if the waveband is 0.47 -0.57m, the measurement of unambiguous distance of 25 -500m can be realized. If the wavelength tolerance error is less than ± 10^-7 and the phase error is less than ± 10 ^-3, the precision of the distance ranging can reach 10^-6.