大赖草总DNA转化小麦叶片mRNA差异显示技术中总RNA提取和反转录活性研究

[目的]研究大赖草总DNA转化小麦叶片mRNA差异显示技术中总RNA的质量及反转录活性。[方法]在大赖草总DNA转化小麦幼苗叶片mRNA差异显示相关试验中,利用改进的TRIzol法,从幼苗叶片中提取总RNA,紫外光谱分析,1.2%琼脂糖电泳检测,并进行随机引物RT-PCR扩增。[结果]OD260 nm/OD280 nm比值为1.95～1.98;总RNA和RT-PCR电泳条带均表现出整齐、清晰。[结论]获得的总RNA质量好、纯度高,有很高的反转录活性,完全适合于进一步的分子生物学研究。

嗜热毛壳菌端粒酶的表达纯化及酶学特性分析

为进一步探究端粒酶的酶学特性,以嗜热毛壳菌(Chaetomium thermophilum, Thermo)端粒酶为研究对象,通过生物化学、生物信息学等方法得到4种不同长度的Thermo端粒酶蛋白,分别与体外转录得到的Thermo端粒酶RNA进行组装。通过端粒酶体外延伸试验检测组装体的反转录活性,进一步分析影响其反转录活性的各种因素。结果表明,4种不同长度的Thermo端粒酶蛋白重组质粒经大肠杆菌表达系统诱导表达后均可得到相应的Thermo端粒酶蛋白,且纯度均在90%以上;体外孵育试验表明,在10 mmol/L HEPES-KOH(pH 8.0)、1 mmol/L MgCl2、100 mmol/L NaCl、3 mmol/L KCl、体积分数25%Glycerol、10units/μL Rnasin的条件下,端粒酶蛋白与RNA的摩尔浓度比达到1∶1及以上时,两者能有效复合;端粒酶体外延伸试验发现,结构完整的Thermo端粒酶组装体具有很强的反转录活性,可使18nt-DNA引物反复延伸。TEN结构域不完整并未减弱Thermo端粒酶组装体的反转录活性,说明其在反转录过程中未发挥显著作用。T-PK区或TWJ区缺失的组装体均不能使18nt-DNA引物发生延伸,表明RNA结构的完整性是端粒酶发挥反转录功能的必要条件。

利用Taq DNA聚合酶直接从双链RNA模板中扩增靶序列

利用Taq DNA聚合酶既具有DNA聚合酶活性义具有反转录酶活性的特点,探索了在Taq DNA聚合酶单独作用下以双链RNA为模板进行PCR反应的条件。结果表明靶序列长度为277 bp、369 bp、987 bp时,均可直接进行PCR扩增;短片段序列扩增的退火温度在47．0℃、47．9℃、50．2℃、52．6℃、54．9℃、56．7℃条件下,均可有效扩增,而长片段序列扩增的退火温度在50．2℃、52．6℃、54．9℃、56．7℃条件下,也可扩增出相应的靶序列。这一结果提示利用Taq DNA聚合酶可以dsRNA为模板直接扩增目的片段,尤其是短片段的扩增。

Effects of octreotide on glucose transporter type 2expression in obese rat small intestine

AIM： TO investigate the effects of the somatostatin analogue, octreotide, on maltose and sucrase activities and expression of glucose transporter type 2 （GLUT2） in obese rat intestinal mucosa. METHODS： We divided 49 Sprague-Dawley rats into a group of 31 high fat diet-induced obese rats and a group of 18 normal controls. The obese rats were separated into an octreotide treated group 9f 16 rats and an obese group of 15. The intervention （：jroup was injected with octreotide at 40 ±g/kg body weight every 12 h for 8 d. Rat body weight was measured weekly to calculate Lee＇s index. After euthanization, maltase and sucrase activities in the small intestine were measured by activity assays, and the fasting plasma glucose level was measured. The expression of GLUT2 in small intestinal mucosa was analyzed by immunohistochemistry, reverse transcriptase polymerase chain reaction and Western blotting assays. RESULTS： Body weight, Lee＇s index, fasting plasma glucose level, maltase activity in small intestinal mucosa, mucosa and apical GLUT2, GLUT2 mRNA and protein expression levels were all significantly higher in the obese group than in the normal control group （605.61 ± 141.00 vs 378.54 ±111.75, 337.61 ± 10.82 vs 318.73 ± 20.10, 8.60± 1.38 vs 7.33 ± 0.70, 156.01 ± 58.81 vs 50.43 ± 30.49, 390 744.2± 62 469.21 vs 170 546.50 ± 50 646.14, 26 740.18 ±3809.60 vs 354.98± 57.19, 0.26± 0.11 vs 0.07± 0.02, and 2.08 ± 0.59 vs 1.27 ± 0.38, respectively, all P 〈 0.01）. Sucrase activity did not differ between the two groups. Octreotide intervention significantly decreased the body weight and fasting plasma glucose level of obese rats （508.27 ± 94.39 vs 605.61 ± 141.00, 7.58 ± 1.51 vs 8.60±1.38, respectively, all P 〈 0.05）. The intestinal mucosa and apical GLUT2, expression of GLUT2 mRNA and protein were also significantly lower in the octreotide intervention group than in the obese group （269 975.2 ± 53 730.94 vs 390 744.2 ± 62 469.21, 3758.06 ± 364.51 vs 26 740.18 ± 3809.60, 0.08 ± 0.02 vs 0.26 ±0.11, and 1.31 ± 0.27 vs 2.08 ±0.59, respectively, all P 〈 0.01）. CONCLUSION： High fat dietinduced obesity is associated with elevated intestinal maltase activity, GLUT2 expression, and permanent apical GLUT2 in the small intestinal mucosa of rats. Octreotide can inhibit these effects.

Hepato-biliary profile of potential candidate liver progenitor cells from healthy rat liver

AIM： To evaluate the presence of progenitor cells in healthy adult rat liver displaying the equivalent ad- vanced hepatogenic profile as that obtained in humans. METHODS： Rat fibroblastic-like liver derived cells （rFLDC） were obtained from collagenase-isolated liver cell suspensions and characterized and their phenotype profile determined using flow cytometry, immunocyto- chemistry, reverse transcription polymerase chain reac- tion and functional assays. RESULTS： rFLDC exhibit fibroblastoid morphology, ex- press mesenchymal （CD73, CD90, vimentin, m-smooth muscle actin）, hepatocyte （UGTIA1, CK8） and biliary （CK19） markers. Moreover, these cells are able to store glycogen, and have glucose 6 phosphatase activity, but not UGTIA1 activity. Under the hepatogenic differentia- tion protocol, rFLDC display an up-regulation of hepatocyte markers expression （albumin, tryptophan 2,3-di- oxygenase, G6Pase） correlated to a down-regulation of the expression of the biliary marker CK19. CONCLUSION： Advanced hepatic features observed in human liver progenitor cells could not be demonstrated in rFLDC. However, we demonstrated the presence of an original rodent hepato-biliary cell type.

Toxicarioside A inhibits SGC-7901 proliferation,migration and invasion via NF-κB/bFGF signaling

AIM:To investigate the inhibitory role of toxicarioside A on the gastric cancer cell line human gastric cancer cell line(SGC-7901) and determine the underlying molecular mechanism.METHODS:After SGC-7901 cells were treated with toxicarioside A at various concentrations(0.5,1.5,4.5,9.0 μg/mL) for 24 h or 48 h,cell viability was determined by 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl2H-tetrazolium bromide assay,and the motility and invasion of tumor cells were assessed by the Transwell chamber assay.Immunofluorescence staining,reverse transcription polymerase chain reaction and Western blotting were performed to detect the expression of basic fibroblast growth factor(bFGF) and fibroblast growth factor receptor-1(FGFR1),and nuclear factorkappa B(NF-κB) activation was examined by electrophoretic mobility shift assay.RESULTS:The results showed that toxicarioside A was capable of reducing cell viability,inhibiting cell growth,and suppressing cell migration and invasion activities in a time-and dose-dependent manner in SGC-7901 cells.Further analysis revealed that not only the expression of bFGF and its high-affinity receptor FGFR1 but also the NF-κB-DNA binding activity were effectively blocked by toxicarioside A in a dose-dependent manner compared with the control group(P < 0.05 or P < 0.01).Interestingly,application of the NF-κB specific inhibitor,pyrrolidinedithiocarbamate(PDTC),to SGC-7901 cells significantly potentized the toxicarioside A-induced down-regulation of bFGF compared with the control group(P < 0.05).CONCLUSION:These findings suggest that toxicarioside A has an anti-gastric cancer activity and this effect may be achieved partly through down-regulation of NF-κB and bFGF/FGFR1 signaling.

Role of Acetylated p53 in Regulating the Expression of map2 in Retinoic Acid-induced P19 Cells

Objective To investigate the regulatory mechanisms of acetylated p53 in the expression of microtubule-associated protein-2(MAP2) in neuronal differentiation of P19 cells induced by all-trans retinoic acid(RA).Methods Neuronal differentiation of P19 cells was initiated with 4-day RA treatment.Immunofluorescence,real-time reverse transcription-polymerase chain reaction(RT-PCR) assay,and map2 promoter driven luciferase assay were performed to detect the expression and relative promoter activity of MAP2 in those RA-treated cells.Real-time PCR-based chromatin immunoprecipitation assay(ChIP) was carried out to reveal the specific recruitment of acetylated p53 onto its binding sites on map2 promoter.Results The expression of MAP2 was markedly increased in RA-induced P19 cells.The map2 mRNA increased 34-fold after 4 days of RA treatment and 730-fold 2 days after the treatment,compared with the cells without RA treatment(control).p53 was recruited to the promoter of map2 gene in acetylated form and thereby enhanced its promoter activity.p300/CBP associated factor(PCAF) was found induced in RA-treated cells and enriched in the nucleus,which might contribute to the acetylation of p53 in the regulation of map2 gene.Conclusions Acetylated p53 may participate in regulating the expression of map2 in RA-induced differentiation of P19 cells.PCAF is possibly involved in this process by mediating the acetylation of p53.

Effect of berberine on activity and mRNA expression of N-acetyl transferase in human lung cancer cell line A549

OBJECTIVE： To study the effects of berberine on ac- tivity and mRNA expression of N-acetyltransferase in human lung cancer cell line A549. METHODS： N-acetyltransferase antibodies wereprepared. The human lung cancer A549 cells were cultivated randomly in the wells of culture plate, and divided into the control group, and berberine 0.0008, 0.008, 0.08, 0.8 and 1.6 mM treatment groups, with 3 wells for each group. 24 h later, A549 cells in each group were collected respectively, the content of N-acetyltransferase was detected by Flow cytometry, and the mRNA expression of N-acetyltransferase was observed by reverse tran- scription polymerase chain reaction. RESULTS The N-acetyltransferase content in hu- man lung cancer A549 cells decreased with the in- creasing of berberine concentration, significantly lower than that in the control group （P〈O.05 or P〈 0.001）; and the mRNA expression of N-acetyltrans- ferase also decreased with the increasing of berber- ine concentration, significantly lower in Huanglian- su treatment groups （P〈0.O01）. CONCLUSION： Berberine can inhibit the activity of N-acetyltransferase in human lung cancer cell line A549, and shows negative correlations of dose and time in a certain extent. The inhibited gene expres- sion of N-acetyltransferase in human lung cancer A549 cell may probably represent one of the mech- anisms for its antineoplastic effect.