转基因花生外源基因田间漂移风险初步研究

用含花生条纹病毒壳蛋白(cp)基因和潮霉素筛选基因(hygr)的转基因花生品系为材料,田间试验表明转基因花生中的hygr基因可在短距离范围内随花粉漂移,离转基因花生种植区边缘1.0m和3.0m范围内漂移频率分别为4.4%和5.0%;3.0m以外范围内,没有检测到hygr基因随花粉发生漂移。各距离范围内均没有检测到cp基因随花粉漂移现象。因此认为,转基因花生外源基因漂移距离在3.0m以内。

Epsps基因为筛选标记的多基因抗虫表达载体构建

目的:为了获得水稻的广谱抗虫性,同时也避免由潮霉素抗性基因引起的安全性问题。构建以抗除草剂基因(Epsps基因)为筛选标记的多基因抗虫植物表达载体pCTSK。方法:以双元载体pCAMBIA1300为基础,将潮霉素抗性基因hpt替换成携带烟草叶绿体转运肽序列TSP的草甘膦抗性突变基因aroAM12(编码细菌5-烯醇式丙酮酸莽草酸-3-磷酸合成酶Epsps)作为筛选标记基因,获得中间表达载体pCTSM1300。然后再连接上3个抗虫基因(马铃薯蛋白酶抑制剂基因Pin-Ⅱ、苏云金杆菌毒蛋白基因Bt cryI(A)及雪花莲外源凝集素基因GNA)的完整表达片段(包含各自的启动子和终止子)。结果:通过PCR方法和酶切方法鉴定已成功地构建了该表达载体;通过不同实验方案的数据分析,得出在载体构建的大分子连接中优化的一次连接法连接效率高于二次连接法的结论。

稳定表达人Eps8基因的胶质瘤U251细胞系的建立

应用亚克隆方法构建pEGFP-C3/Eps8真核表达载体,经测序鉴定后,用脂质体进行胶质瘤U251细胞的转染,应用G418筛选出稳定表达pEGFP-C3/Eps8和pEGFP-C3的细胞系,最后通过Western blot和荧光定位证明Eps8在U251细胞中过量表达。本实验成功建立了稳定转染Eps8的U251细胞系,为进一步研究Eps8基因在胶质瘤中的功能奠定了良好的实验基础。

Overexpression of IGF2R and IGF1R mRNA in SCNT-produced Goats Survived to Adulthood

The procedure of somatic cell nuclear transfer （SCNT） is likely to affect the expression level of growth-related genes especially imprinting genes. In this study, expressions of growth-related genes including three imprinting genes （H19, IGF2, and IGF2R） and four non-imprinting genes （IGF1, IGFIR, GHR, and GHSR） in adult nuclear transferred （NT） goats were investigated by real-time PCR. The expressions of these genes in adult clones were found largely normal, but IGF2R and IGFIR were more highly expressed in cloned goats than in non-NT goats （P 〈 0.01）. Analysis on mono-allelic expression pattern of imprinting genes indicated that mono-allelic expression patterns of H19 and IGF2 in cloned goats were similar to that in non-NT goats. In addition, the sequence of goat IGF2 gene and the putative amino acid sequence were obtained. The 986 nucleotide cDNA of goat IGF2 gene contained an open-reading frame of 540 nucleotides coding for 179 amino acids. Both cDNA sequence and amino acid sequence of IGF2 in goat showed their higher homology with that in sheep than in cattle; the partial cDNA fragments of H19, IGF2R, GHSR, IGFIR, and GHR in goat were also cloned and sequenced, which shared higher sequence identities with those in sheep than in cattle.

Plant Genomic Imprinting and Its Effect on Seed Development

Genomic imprinting is the epigenetic phenomenon by which certain genes are expressed in a parent-of-origin-specific manner, and was first discovered in mammalian embryos. Recent studies have shown that it also occurs in developing plant seeds, and is now becoming a hot topic of biology of plant seed development. According to the previous studies on imprinted genes, imprinting mechanism and their roles in plant seed development, the current progress of genomic imprinting in plant seed development was summarized and possible strategies were proposed to deal with the problems, which could provide helpful information for further research.

Expression of Ferric Chelate Reductase Gene in Citrus junos and Poncirus trifoliataTissues

It has been hypothesized that under iron stress high ferric chelate reductase (FCR) activity in the absorptive root of plants tolerant to iron_deficiency will be induced and result in subsequent Fe 2+ transport across the plasmalemma. The activity of FCR and expression of FCR gene (FRO2) in Citrus junos Sieb. ex Tanaka tolerant to iron_deficiency and Poncirus trifoliata (L.) Raf. susceptible to iron_deficiency were determined to elucidate the physiological difference which causes the different tolerance of the two citrus rootstocks to iron stress. The activity of FCR was detectable in excised roots and was stimulated about 20_times in C. junos and only about 3_times in P. trifoliata under iron deficiency for four weeks. The FRO2 of Arabidopsis was used as a probe, the tissue print technique was used to ascertain the expression of the FCR gene in C. junos and P. trifoliata under iron stress. High_level transcripts were observed in the absorptive root, young green stem as well as new leaf of C. junos under iron stress for two weeks, and the transcripts were accumulated only slightly in P. trifoliata at the same time. The results showed that the obvious increase of FCR activity was an important reason for the tolerance of C. junos to iron_deficiency, and the regulation of FCR activity seemed to be at the transcriptional level, and the expression of FRO2 occurred in the root, stem and leaf.

Molecular Genetic Diagnostics of Prader-Willi Syndrome:a Validation of Linkage Analysis for the Chinese Population

Prader-Willi Syndrome （PWS） is a genetic disorder that is difficult to detect, particularly at an early age. PWS is caused by disruption of normal, epigenetically controlled gene function in the chromosome 15q11-q13 region. Clinical symptoms are difficult to diagnose in infants and only become clearer at later ages as the patients develop hyperphagia and morbid obesity. Molecular genetic tests are able to definitively diagnose PWS and allow early diagnosis of the syndrome. High resolution cytogenetic testing, methylation-specific PCR （MS-PCR）, and linkage analysis are routinely used to diagnose PWS. To establish a linkage analysis method for Chinese patients, this study identified a useful set of STR markers in the typical PWS deletion and adjacent area, for linkage analysis in two Chinese families with PWS offspring. Using this method, the authors confn＇rned that one patient had a paternal deletion in chromosome 15q 11-q 13 and the other patient had maternal uniparental heterodisomy of chromosome 15. MS -PCR and high resolution chromosome G-banding also confirmed this diagnosis. This linkage analysis method can detect both deletion and uniparental disomy, thus providing valuable information for genetic counseling and the opportunity to analyze the relationship between the genotype and phenotype of PWS.

cDNA Cloning and Expression Analysis of Mest Gene in the Bufo gargarizans

The Mest （mesoderm-specific transcript） gene has been considered an imprinting gene in human and mouse, and was also confirmed in other mammals and flowering plants. To investigate the function and evolution of this gene, the cDNA of full length Mest gene was obtained using 5＇- and 3＇-RACE from the Chinese Large Toad （Bufo gargarizans）. The transcript is 1 325bp in length which contains a complete open reading frame （ORF） encoding a polypeptide of 326 amino acids （GenBank accession number： ABQ10905）. There is a typical 0./13 hydrolase fold domain in the putative gene product, and it shows high similarity to sequence of homologous protein of Xenopus tropicali （86%）, mammlian （70% - 80%）. RT-PCR （reverse transcriptase-polymerase chain reaction） analysis demonstrated that the Bufo gargarizans Mest （BgMest） gene is expressed widely in testis, ovary, liver, kidney, spleen, brain, stomach and lung. The conservation of the BgMest gene sequences, protein secondary structure of the BgMest protein, in addition to the expression pattern of the BgMest gene, suggested that the function of BgMest was conserved in amphibians. However, the phylogenetic tree of the imprinting gene of the mammals and other vertebrates examined in this study indicated their divergent origins.

Epigenetics and neural stem cell commitment

Neural stem cell is presently the research hotspot in neuroscience. Recent progress indicates that epigenetic modulation is closely related to the self-renewal and differentiation of neural stem cell. Epigenetics refer to the study of mitotical/meiotical heritage changes in gene function that cannot be explained by changes in the DNA sequence. Major epigenetic mechanisms include DNA methylation, histone modification, chromatin remodeling, genomic imprinting, and non-coding RNA. In this review, we focus on the new insights into the epigenetic mechanism for neural stem cells fate.

Torque teno virus:Its prevalence and isotypes in North India

AIM： To investigate the prevalence and genotype distribution of Torque teno virus （TTV） in patients with different liver diseases and chronic renal failure treated at a referral hospital in North India. METHODS： Whereas prevalence of TFV was based on amplification of conserved region of ORF2 of TTV genome, the genotyping of TFV was carried out using restriction fragment length polymorphism （RFLP） procedure on the N22 region of ORFI. RESULTS： TTV-DNA was detected in 137 of 513 （26.7%） patients with liver diseases and 38 of 65 （58.5%） patients with chronic renal failure. Trv was also detected in 2/7% of healthy controls. The sequence analysis of the PCR product from 10 randomly selected cases failed to show a significant sequence divergence when compared with that of the TRM1 isolate of TTV genotype 1. The results of genotyping in 55 randomly selected patients showed the presence of genotype 1 （G1） in 53 （96.4%） and genotype 2 （G2） in 2 cases （3.6%）, respectively. Other genotypes were not identified in this patient subgroup, suggesting that G1 is predominant in this area. The results of genotyping by RFLP were also supported by phylogenetic tree analysis, where G1 was found to be the major genotype. CONCLUSION： These results indicate that TTV is moderately present in Indian patients, with G1 to be the major genotype in North India. The pathogenicity and etiological role of TTV in different diseases is still a question mark and warrant further studies.

Expression of PADI4 in hepatocellular carcinoma

Objective： The aim of the research was to study peptidylarginine deiminase type 4 （PAD4/PADI4） expression and its tumodgenic mechanism in hepatocellular carcinomas. Methods： Expressions of PADI4 and p53 were investigated in tumors and non-tumor tissues by Western blot in patients with hepatocellular carcinomas. We constructed plasmid of PADI4-Flag and transfected it in Hela cells to investigate the mechanism. Results： Western blot analysis showed higher PADI4 expression in hepatocellular carcinomas than in the surrounding healthy tissues. Furthermore, by Western blot, we detected decreased p53 levels in the tumor tissues of patients with hepatocellular carcinomas compared to surrounding healthy tissues. In Hela cells transfected with PcDNA3.0-Flag-PADI4 plasmid, the expression of p53 decreased obviously. Conclusion： Our results suggest that PADI4 elevated in the tissues of hepatocellular carcinomas and induced tumorigenic by down-regulating p53 expression.

Nonalcoholic steatohepatitis in Asian Indians is neither associated with iron overload nor with HFE gene mutations

AIM: The pathogenesis of occurrence of liver inflammation and fibrosis in patients with nonalcoholic steatohepatitis (NASH) is not completely understood. Other than insulin resistance, iron abnormalities have been thought to be one of the triggering factors. Therefore, our aim was to study the role of iron abnormalities and HFE gene mutations in patients with NASH. METHODS: Thirty-one patients of NASH diagnosed on the basis of clinical examination biochemistry, ultrasonography and liver biopsy (n = 14) were included in the study. Serum iron parameters (n = 23) (iron, ferritin, total iron-binding capacity and transferrin saturation), Perls' iron staining on liver biopsies (n = 14) and HFE gene mutations (C282Y and H63D) (n = 16) were studied in these patients. The association between iron staining, necroinflammatory activity and fibrosis stage on liver biopsies was also determined. RESULTS: Elevated serum iron, ferritin and transferrin saturation above 55% were observed in 4.3% of patients. On histology, 71% of the patients had negative iron staining, 21.4% had 1+ staining, 7.2% had 2+ staining and none had 3+ or 4+ staining. There was no association between the degree of iron staining and necroinflammatory activity (P=0.55) and fibrosis stage (P= 0.09) on histology. None of the patients had C282Y HFE gene mutation and four patients (25%) were found to be heterozygotes for H63D gene mutation. CONCLUSION: Our study does not favor iron overload and HFE gene mutations as major factors in the pathogenesis of NASH in Asian Indians.

Molecular mechanism and functional consequences of lansoprazole-mediated heme oxygenase-1 induction

AIM： To investigate the molecular mechanism and functional consequences of heme oxygenase-1 （HO-1） activation by lansoprazole in endothelial cells and macrophages. METHODS： Expression of HO-1 mRNA was analyzed by Northern blotting. Western blotting was used to determine the HO-1 and ferritin protein levels. NADPH-dependent reactive oxygen species （ROS） formation was measured with lucigenin-enhanced chemiluminescence. HO-1 promoter activity in mouse fibroblasts, stably transfected with a 15-kb HO-1 gene that drives expression of the reporter gene luciferase, was assessed usingin vivo bioluminescence imaging. RESULTS： Lansoprazole levels in endothelial cells increased HO-1 mRNA and HO-1 protein levels in macrophages. In addition, lansoprazole-induced ferritin protein levels in both cell systems. Moreover, induction of the antioxidant proteins HO-1 and ferritin by lansoprazole was followed by a decrease in NADPH- mediated ROS formation. The radical scavenging properties of lansoprazole were diminished in the presence of the HO inhibitor, chromium mesoporphyrin IX. Induction of HO-1 gene expression by lansoprazole was not related to oxidative stress or to the activation of the mitogen-activated protein kinase pathway. However, the phosphatidylinositol 3-kinase inhibitor LY294002 showed a concentration-dependent inhibition of HO-1 mRNA and promoter activity.CONCLUSION： Activation of HO-1 and ferritin may account for the gastric protection of lansoprazole and is dependent on a pathway blocked by LY294002.

Adeno-associated virus mediated endostatin gene therapy in combination with topoisomerase inhibitor effectively controls liver tumor in mouse model

AIM:rAAV mediated endostatin gene therapy has been examined as a new method for treating cancer.However, a sustained and high protein delivery is required to achieve the desired therapeutic effects.We evaluated the impact of topoisomerase inhibitors in rAAV delivered endostatin gene therapy in a liver tumor model. METHODS:rAAV containing endostatin expression cassettes were transduced into hepatoma cell lines.To test whether the topoisomerase inhibitor pretreatment increased the expression of endostatin,Western blotting and ELISA were performed.The biologic activity of endostatin was confirmed by endothelial cell proliferation and tube formation assays. The anti-tumor effects of the rAAV-endostatin vector combined with a topoisomerase inhibitor,etoposide,were evaluated in a mouse liver tumor model. RESULTS:Topoisomerase inhibitors,including camptothecin and etoposide,were found to increase the endostatin exPression level in vitro.The over-expressed endostatin, as a result of pretreatment with a topoisomerase inhibitor, was also biologically active.In animal experiments,the combined therapy of topoisomerase inhibitor,etoposide with the rAAV-endostatin vector had the best tumor- suppressive effect and tumor foci were barely observed in livers of the treated mice.Pretreatment with an etoposide increased the level of endostatin in the liver and serum of rAAV-endostatin treated mice.Finally,the mice treated With rAAV-endostatin in combination with etoposide showed the longest survival among the experimental models. CONCLUSION:rAAV delivered endostatin gene therapy in combination with a topoisomerase inhibitor pretreatment is an effective modality for anticancer gene therapy.

Gene expression profile of esophageal cancer in North East India by cDNA microarray analysis

AIM： To identify alterations in genes and molecular functional pathways in esophageal cancer in a high incidence region of India where there is a widespread use of tobacco and betel quid with fermented areca nuts. METHODS： Total RNA was isolated from tumor and matched normal tissue of 16 patients with esophageal squamous cell carcinoma. Pooled tumor tissue RNA was labeled with Cy3-dUTP and pooled normal tissue RNA was labeled with Cy5-dUTP by direct labeling method. The labeled probes were hybridized with human 10K cDNA chip and expression profiles were analyzed by Genespring GX V 7.3 （Silicon Genetics）. RESULTS： Nine hundred twenty three genes were differentially expressed. Of these, 611 genes were upregulated and 312 genes were downregulated. Using stringent criteria （P ≤ 0.05 and ≥ 1.5 fold change）, 127 differentially expressed genes （87 upregulated and 40 downregulated） were identified in tumor tissue. On the basis of Gene Ontology, four different molecular functional pathways （HAPK pathway, G-protein coupled receptor family, ion transport activity, and serine or threonine kinase activity）were most significantly upregulated and six different molecular functional pathways （structural constituent of ribosome, endopeptidase inhibitor activity, structural constituent of cytoskeleton, antioxidant activity, acyl group transferase activity, eukaryotic translation elongation factor activity）were most significantly downregulated. CONCLUSION： Several genes that showed alterations in our study have also been reported from a high incidence area of esophageal cancer in China. This indicates that molecular profiles of esophageal cancer in these two different geographic locations are highly consistent.

Effect of ALA-PDT on the expressions of MMP-9, MMP-13 and TIMP-1 of hypertrophic scar model in rabbit ears

Objective: To investigate the effect of 5-aminolevulinic(ALA)-photodynamic therapy(PDT) on the expressions of MMP-9, MMP-13 and TIMP-1 of hypertrophic scar model in rabbit ears, and analyze the possible therapeutic mechanisms of ALA-PDT treatment to hypertrophic scars of rabbit ears. Methods: The experimental animals were randomly divided into normal control, negative control, high concentration of ALA-PDT, low concentration of ALA-PDT and PDT groups. The latter three groups received ALA-PDT treatment or PDT treatment once a week for 3 weeks. The specimens of the rabbits were collected respectively 1, 2 and 3 months after treatment to be used for RT-PCR and Western-blot test. Results: 1, 2 and 3 months after PDT treatment, the expressions of MMP-9 and MMP-13(including mRNA and protein) in hypertrophic scar tissues of three treatment groups were significantly higher than those of the negative control group(P<0.01), and the expression of TIMP-1 mRNA and protein of three treatment groups were significantly lower than that of the negative control group(P<0.01). There were also significant differences between high-concentration ALA-PDT treatment group and the low one(P<0.05). Conclusion: ALA-PDT is effective in treating hypertrophic scars of rabbit ears, and its possible therapeutic mechanisms are that ALA-PDT treatment generates oxidation activation effect to activate the activity of MMPs and induces the photoaging of fibroblasts of hypertrophic scar tissues of rabbit ears to inhibit the activity of TIMPs, which causes the up-regulation of MMPs and the down-regulation of TIMPs. Because of this, the degradation of collagen and ECM is accelerated and the formation of scars is suppressed.

Decreased expression of Neurensin-2 correlates with poor prognosis in hepatocellular carcinoma

AIM： To investigate the expression of Neurensin-2 （NRSN2） in hepatocellular carcinoma （HCC） and its prognostic values in predicting survival. METHODS： The expression and prognostic significance of NRSN2 in HCC was examined by performing immunohistochemical analysis using a total of 110 HCC clinical tissue samples, and Western blotting analysis to further confirm the result. RESULTS： Decreased NRSN2 expression was shown in 70.9% cases. Loss of NRSN2 expression in HCC was significantly related to tumor size （P = 0.006）. Larger tumor size was related to negative expression of NRSN2. Patients showing negative NRSN2 expression had a significantly shorter overall survival than those with positive expression （P = 0.008）. Multivariate Cox regression analysis indicated that NRSN2 expression level was an independent factor of survival （P = 0.013）. Western blotting analysis further confirmed decreased expression of NRSN2 in tumor tissues compared with non-tumorous tissues. CONCLUSION： Our study indicated that NRSIV2 could be a tumor suppressor gene for HCC and a candidate biomarker for long-term survival in HCC.

QIM digital watermarkingbased on LDPC code and messagepassingunder scalingattacks

Watermarking system based on quantization index modulation （QIM） is increasingly popular in high payload applications,but it is inherently fragile against amplitude scaling attacks.In order to resist desynchronization attacks of QIM digital watermarking,a low density parity check （LDPC） code-aided QIM watermarking algorithm is proposed,and the performance of QIM watermarking system can be improved by incorporating LDPC code with message passing estimation/detection framework.Using the theory of iterative estimation and decoding,the watermark signal is decoded by the proposed algorithm through iterative estimation of amplitude scaling parameters and decoding of watermark.The performance of the proposed algorithm is closer to the dirty paper Shannon limit than that of repetition code aided algorithm when the algorithm is attacked by the additive white Gaussian noise.For constant amplitude scaling attacks,the proposed algorithm can obtain the accurate estimation of amplitude scaling parameters.The simulation result shows that the algorithm can obtain similar performance compared to the algorithm without desynchronization.

Correlation of p53 over-expression and alteration in p53 gene detected by polymerase chain reaction-single strand conformation polymorphism in adenocarcinoma of gastric cancer patients from India

AIM： To study the alterations in p53 gene among Indian gastric cancer patients and to correlate them with the various clinicopathological parameters. METHODS： A total of 103 gastric cancer patients were included in this study. The p53 alterations were studied by both immunohistochemical method as well as polymerase chain reaction （PCR）-single strand conformation polymorphism （SSCP） analysis. We only studied four （exon 5, 6, 7, and 8） of the 11 ,p53 exons. The alterations in p53 were also correlated with respect to various clinicopathological parameters. RESULTS： Among 103 cases, p53 over-expression and alteration were detected in 37 （35.92%） and 19 （18.44%） cases, respectively. Most of the ,p53 alterations were found at exon 5 （31.54%）, followed by exon 6 （26.31%）, exon 7 （21.04%） and exon 8 （21.04%）. A significant correlation of p53 overexpression was found with p53 alteration （P = 0.000）. Concordance between ,p53 alteration （as detected by SSCP） and over-expression [as detected by immunohistochemistry （IHC）] was found in 75% cases. We found that IHC-positive/SSCP-negative cases accounted for 21% of cases and IHC-negative/SSCP- positive cases accounted for remaining 4% cases. CONCLUSION： Our results show that p53 gene mutations are significantly correlated with p53 protein over-expression, with 75% concordance in over-expression and alteration in the p53 gene, but 25% disconcordance also cautions against the assumption that p53 over-expression is always associated with a gene mutation. There may be other mechanisms responsible for stabilization and accumulation of p53 protein with no evidence of gene mutation that reflect an accumulation of a non-mutated protein, or a false negative SSCP result.