含铬低合金钢在海水全浸腐蚀过程中“逆转”机理的研究

通过含铬低合金钢的实海全浸试验和腐蚀试样锈层的分析研究 ,针对含铬低合金钢在海水全浸腐蚀中产生的“逆转”现象 ,应用电化学原理 ,提出了含铬低合金钢在海水腐蚀时的微电池腐蚀机理模型 ,较好地解释了这种“逆转”

公众参与方式与社会转型中的“逆转型”现象——以Y市政府搬迁中的公众参与为例

以Y市政府搬迁为例,探讨了地方政府如何通过"动员式公众参与"的方法推动完成了迁市过程,也引发"社会逆转型"危机。与中国绝大多数地区经历的转型过程相反,Y市的社会转型呈现出了一种"逆转"的现象,即从以工业为主的现代社会形态向以农业生产加工为主体的农业社会转变。Y市案例提示我们,在制定公共政策方面需要实现彻底的转型,即从政治动员式公众参与向权利性公众参与的转型。这种转型的完成不仅需要公众公民意识的觉醒,更需要将社会政策、政策制定者和公众带入公共领域,实现社会学知识范式的转换。

系统功能观照下的“逆转换”模式

为阐释翻译过程,奈达借助乔姆斯基的转化生成语法提出了翻译的"逆转换"模式。该模式与韩礼德的系统功能语法有很多共通之处,两者均立足于语义分析,且都强调语言的社会语境与功能属性。本文在系统功能语法的观照下对奈达的"逆转换"模式进行了重新阐述。

Study on the Homologous Sequences of copia-like Retrotransposons in a Twin ovary Mutant of Rice

A twin ovary mutant derived from the doubled haploid (DH) progeny of a cross,02428/Gui 630, was presumably related to the transposition of some transposable elements. Up to date, all reported the active transposable elements in rice (Oryza sativa L.) are copia like retrotransposons. In the present study, the reverse transcriptase domains of copia like retrotransposons were amplified from the total DNA isolated from the mutant plants with the degenerated oligonucleotide primers for the domain. Three cloned insert DNAs, R33 1, R33 4 and R33 8, representing putative different copia like retrotransposons were screened out. Two of them displayed high polymorphism between “Zhaiyeqing 8” and “Jingxi 17”. Nine of the polymorphic bands were mapped on seven rice chromosomes. Sequencing analysis revealed that stop codons frequently occur in the sequence of R33 8, while both R33 1 and R33 4 contain a continuous coding region for 81 putative amino acid residues. No significant variation in hybridization patterns was found between indica and japonica rice or among 26 varieties of indica rice when R33 1 was used as a probe. Nevertheless, when R33 4 was used as a probe, high polymorphisms were detected both between indica and japonica rice and among 26 indica varieties, implying that this element might still be active in rice genomes.

Research Advance on Molecular Mechanism of Abiotic and Biotic Stress Resistance in Sweet Potato

Sweet potato（Ipomoea batatas） is not only an important food crop, but also an important economic crop and energy crop. In recent years, as the develop- ment of molecular biology techniques, more and more abiotic and biotic stress-related genes were discovered in sweet potato. These genes can be divided into two categories： the regulatory genes and the functional genes, according to their different roles in stress pathways. This paper reviews the abiotic and biotic stress-related genes cloning, functional analysis and exogenous genes application in sweet potato, and makes expectation for stress resistance research of sweet potato in the future.

Screening an Na^+/H^+ Antiporter Gene from the Halophiles Colonizing in the Dagong Ancient Brine Well of Zigong City,China

[Objective] This study aimed to screen an Na＋/H＋ antiporter gene from the halophiles colonizing in the Dagong Ancient Brine Well in Zigong City, China, and then analyze the gene structure and properties of the protein encoded by this gene. [Method] Metagenomic DNA libraries of halophiles from the Dagong Ancient Brine Well were used for screening genes with Na＋/H＋ antiporter activity in antiporter-defi- cient E. coil KNabc strain by functional complementation. Then the start codon, stop codon, ORF, -35 region, -10 region and SD sequence of Na~/H＋ antiporter gene, as well as the molecular weight, isoelectric point, hydrophobic region, transmembrane domain, phyletic evolution and salt resistance of protein encoded by the gene were investigated. [Result] A new Na＋/H＋ antiporter gene m-nha was obtained, which ,ren- dered the antiporter-negative mutant E. coil KNabc cells with both the resistance to Na＋ and the ability to grow under alkaline conditions. [Conclusion] The structure and amino acid sequence of M-Nha was different from the previously reported Na＋/H~ antiporters, and the m-nha gene disclosed from the Dagong Ancient Brine Well was identified as a novel Na＋/H＋ antiporter gene. This study was significant not only in helping us understand the salt tolerance of halophiles in ancient brine wells and develop and utilize the genes resource, but also in exploring new salt-tolerant genes.

Application of Real-time Fluorescent Quantitative PCR in Plant

Real-time fluorescent quantitative PCR （RQ-PCR） is a detection method by adding fluorescent dye or fluorescent probe into the PCR reaction system, using fluorescent signal accumulation to monitor amplification reactions of PCR reaction process, and finally the unknown template can be quantitatively analyzed through the standard curve. So the detection level of PCR has improved from the qualitative to the quantitative. In order to provide a theoretical reference for further application, the principle, classification, advantages and disadvantages of RQ-PCR were intro- duced, and its application and progress in plants in recent years were reviewed.

Construction of pINC-lacZ Retroviral Vector and its Expression in Mouse Embryonic Stem Cells

A retroviral vector pINC-lacZ containing an E coli β-galactosidase(β-gal)gene was constructed and introduced into the MESPU-13 cells by electroporation.Four G418-resistant colonies were obtained from 1×107,electroporated MESPU-13 cells. Histochemical staining for β-gal activity showed that lacZ gene was expressed in at least three of the four colonies.Southern analysis proved that one copy of foreign gene was integrated in the chromosome of one of the transformed lines(MC15).These results showed that the expression of lacZ gene driven by SiCMVIE promoter can be detected in the transformed MESPU-13 cells.

大学生户籍迁移行为调查及影响因素分析

在加快推进户籍人口城镇化的背景下,相关数据却显示,近年来大学生入学时的户籍迁移量呈下降趋势,大学生户籍迁移似乎出现从城市转向农村的"逆转"现象。通过对地处广州市的某农业类省属一本高校1604名大学生的问卷调查和计量模型分析发现,大学生户籍迁移行为与性别、家庭收入和迁出地集体经济是否有分红等之间不存在显著的关系,与父亲职业、母亲受教育水平、迁出地的城市级别、是否迁入地工作、迁出地是否有土地具有显著相关性。

Research of AtNHX1 Gene Transformation in Brassica napus L. by Agrobacterium tumefaciens

[Objective] The aim was to investigate AtNHX1 gene transformation in Brassica napus L. mediated by Agrobacterium tumefaciens. [Method] By using Agrobacterium-mediated method and cre/lox plant expression vector,the transformation of AtNHX1 gene of Na＋/H＋ antiporter in Brassica napus was studied. [Result] The regeneration rate of cotyledon with petiole was much higher than that of hypocotyl,thus,the cotyledon with petiole was selected as the recipient for transformation. After the cotyledon with petiole was soaked in bacterial solution （OD600=0.4） for 8-10 min,kanamycin-resistant green seeding percentage could reach 3.75%. [Conclusion] The PCR detection of kanamycin-resistant plants proved that NHX1 gene had been inserted into Brassica napus genome. And this research could provide a new way to improve the salt tolerance of Brassica napus.

Expression of Endogenous Beta Retroviruses and Hyal-2 mRNA in Immune Organs of Fetuses and Lambs

Endogenous beta retroviruses (enJSRV) are highly homologous with Jaagsiekte sheep retrovirus (exJSRV),this exogenous retrovirus is the aetiological agent of ovine pulmonary adenocarcinoma (OPA). The aim of this study was to clarify the function of enJSRV and the immunological mechanisms of its corresponding antibody, that is undetectable in JSRV-infected ovine serum. The expression of enJSRV envelope protein and Hyal-2 mRNA in immune organs and lungs of ovine fetuses and lambs were analyzed by Real-Time reverse transcription PCR and In Situ Hybridization using specific probes. In Situ Hybridization results indicated that the enJSRV envelope protein and Hyal-2 mRNA were expressed in thymus, spleen, mesenteric lymph nodes and lungs at different times, while no positive signals were detected in the negative controls. On the other hand, results from Real-Time reverse transcription PCR analysis showed that in 130d fetuses and 3d newborn lambs the enJSRV mRNA levels were much higher in organs associated with the immune system than that in lungs, especially in the thymus and spleen, but levels of Hyal-2 mRNA expression was not significantly different in all collected tissue. These results provided evidence from an immunology point of view to understand why the circulating antibodies against exJSRV are undetectable in JSRV-infected ovine, and will help to unravel the pathogenesis of JSRV-infected ovine.

Expression of Major Antigen Domains of E2 Gene of CSFV and Analysis of its Immunological Activity

E2 is an envelope glycoprotein of Classical swine fever virus (CSFV) and contains sequential neutralizing epitopes to induce virus-neutralizing antibodies and mount protective immunity in the natural host. In this study, four antigen domains (ABCD) of the E2 gene was cloned from CSFV Shimen strain into the retroviral vector pBABE puro and expressed in eukaryotic cell (PK15) by an retroviral gene expression system, and the activity of recombinant E2 protein to induce immune responses was evaluated in rabbits. The results indicated that recombinant E2 protein can be recognized by fluorescence antibodies of CSFV and CSFV positive serum (Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China) using Western blot, indirect immunofluorescence antibody test (IFAT) and ELISA, Furthermore, anti-CSFV specific antibodies and lymphocyte proliferation were elicited and increased by recombinant protein after vaccination. In the challenge test, all of rabbits vaccinated with recombinant protein and Chinese vaccine strain (C-strain) were fully protected from a rabbit spleen virus challenge. These results indicated that a retroviral-based epitope-vaccine carrying the major antigen domains of E2 is able to induce high level of epitope-specific antibodies and exhibits similar protective capability with that induced by the C-strain, and encourages further work towards the development of a vaccine against CSFV infection.

Salvianolate inhibits cytokine gene expression in small intestine of cirrhotic rats

AIM:To study the effect of salvianolate on expression of tumor necrosis factor (TNF)-α and interleukin (IL)-6 mRNA in small intestine of cirrhotic rats. METHODS:Cirrhosis in rats was induced using CCl4 (0.3 mL/kg). Rats were randomly divided into non-treatment group,low-dose salvianolate (12 mg/kg) treatment group,medium-dose salvianolate (24 mg/kg) treatment group,and high-dose salvianolate (48 mg/kg) treatment group,and treated for 2 wk. Another 10 healthy rats served as a normal control group. Mortality of cirrhotic rats in each group was evaluated after treatment with salvianolate. Serum samples were taken from portal vein for the detection of endotoxin. Morphological changes in tissue samples from the ileocecum were observed under a light microscope. Expression of TNF-α and IL-6 mRNA in the small intestine of rats was analyzed by real-time reverse-transcriptase polymerase chain reaction. RESULTS:The mortality of cirrhotic rats in the nontreatment group was 37.5%. No cirrhotic rat died in the high-dose salvianolate treatment group. The serum endotoxin level was significantly higher in the non-treatment group than in the salvianolate treatment and normal control groups. The intestinal mucosal and villous atrophy,necrosis and shedding of the intestinal mucosal epithelium,observed in the non-treatment group,were reversed in different salvianolate treatment groups. The TNF-α and IL-6 mRNA expression levels in small intestine were significantly lower in different salvianolate treatment groups than in the non-treatment group. CONCLUSION:Salvianolate can reduce the endotoxin level,ameliorate the injury of intestinal mucosa,and inhibit the expression of TNF-α and IL-6 mRNA in small intestine of cirrhotic rats.

Aberrant methylation of the 3q25 tumor suppressor gene PTX3 in human esophageal squamous cell carcinoma

AIM:To identify the novel methylation-silenced gene pentraxin 3(PTX3) in esophageal squamous cell carcinoma(ESCC).METHODS:PTX3 mRNA expression was examined in six human ESCC cell lines,one human immortalized normal esophageal epithelial cell line,primary ESCC tumor tissue,and paired adjacent nontumor tissue using reverse transcription polymerase chain reaction(RTPCR).Semi-quantitative immunohistochemistry was used to examine cellular localisation and protein levels.Methylation specific PCR and bisulphite genomic sequencing were employed to investigate the methylation of the candidate gene.RESULTS:In the majority of ESCC cell lines,we found that PTX3 expression was down-regulated due to gene promoter hypermethylation,which was further confirmed by bisulphite genomic sequencing.Demethylation treatment with 5-aza-2'-deoxycytidine restored PTX3 mRNA expression in ESCC cell lines.Methylation was more common in tumor tissues(85%) than in adjacent nontumor tissues(25%)(P < 0.01).CONCLUSION:PTX3 is down-regulated through promoter hypermethylation in ESCC,and could potentially serve as a biomarker of ESCC.

Experimental Therapy for Solid Tumor by in situ Retroviral-mediated Gene Transfer

Although chemotherapy plays a main role in treatment for cancer, gene therapy is thought to be a promising approach of treatment for the future. Thymidine-Kinase gene was delivered into proliferating cells by a retroviral mediated gene transfer system in the culture cells. Later treatment with GCV showed definite cytotoxic effect on the HSV-tk modified cells and the effect correlated with the growth rate of cells. The rapid proliferating tumor cells, HR8348, were inhibited more efficiently than slow proliferating cells. In experiment in vivo , the introduced TK producer cells released virus particles continuously into their neighbor and, as compared with the control, GCV treatment exerted remarkable inhibitory effect on the growth of tumor. The inhibition also correlated with the number of injected TK producer cells. With administration of 0.2 ml of #795 tumor cell suspension(100 ng/ml), coinjection of 2 ×106 TK producer cells achieved 37% inhibition while that of 1 ×107 TK producer cells achieved 66% inhibition,though complete regression could not be achieved under such circumstances.Our result suggests that TK gene transfer followed by GCV treatment merits further evaluation as an effective antineoplastic approach.

Effects of resistin-like molecule β over-expression on gastric cancer cells in vitro

AIM: To investigate the effects of resistin-like molecule β (RELMβ) over-expression on the invasion, metastasis and angiogenesis of gastric cancer cells. METHODS: Human RELMβ encoding expression vec tor was constructed and transfected into the RELMβ lowly-expressed gastric cancer cell lines SGC7901 and MKN-45. Gene expression was measured by Western blotting, reverse transcription polymerase chain reaction (PCR) and real-time quantitative PCR. Cell proliferation was measured by 2-(4,5-dimethyltriazol-2-yl)-2,5-diphenyl tetrazolium bromide colorimetry, colony formation and 5-ethynyl-20-deoxyuridine incorporation assays. The in vitro migration, invasion and metastasis of cancer cells were measured by cell adhesion assay, scratch assay and matrigel invasion assay. The angiogenic capabilities of cancer cells were measured by tube formation of endothelial cells. RESULTS: Transfection of RELMβ vector into SGC-7901 and MKN-45 cells resulted in over-expression of RELMβ, which did not infl uence the cellular proliferation. However, over-expression of RELMβ suppressed the in vitro adhesion, invasion and metastasis of cancer cells, accompanied by decreased expression of matrix metalloproteinase-2 (MMP-2) and MMP-9. Moreover, transfection of RELMβ attenuated the expression of vascular endothelial growth factor and in vitro angiogenic capabilities of cancer cells. CONCLUSION: Over-expression of RELMβ abolishes the invasion, metastasis and angiogenesis of gastric cancer cells in vitro, suggesting its potentials as a novel therapeutic target for gastric cancer.

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.

微分法与积分法差别浅析

尽管可以“逆转”导数公式与法则而得到不定积分的公式与法则(互逆运算),但导数的“构造性”定义给出了由函数f(x)求得它的导数的确定的运算步骤,而原函数定义(F’(x)=f(x))并没有给出如何由f(x)去求得F(x);另外,根据导数的复合运算和四则运算法则,可以把一个复杂函数的导数问题转化为构成这个复杂函数的“元件”函数的导数,积分法则却不能(两者的差别).