Selection and Characterization of a Peptide Specifically Targeting to Gastric Cancer Cell Line SGC-7901 Using Phage Display

Peptides selected from phage display have great potential to become probes for the imaging detection of the cancer. To develop the peptide probe for diagnosis of GC, a 12-mer phage display library was used to select peptides that bind specifically to the human GC cell line SGC-7901. After four rounds of in vitro selection, five phage clones that bound specifically to the SGC-7901 cells were selected. The phage clone GP-5 had a particularly high affinity and specificity for SGC-7901 cells. This clone was identified using a series of methods. The peptide GP-5 that was displayed on phage GP-5 exhibited high specificity to SGC-7901 cells and gastric tissues. Thus, the peptide GP-5 displays excellent potential for imaging detection of human gastric cancer.     

Inactivation of PI3K/Akt signaling mediates proliferation inhibition and G2/M phase arrest induced by andrographolide in human glioblastoma cells

AimsAndrographolide, a principal diterpenoid lactone isolated from the traditional herbal medicine Andrographis paniculata, has been reported to show anti-tumor activity. Since the high lipid solubility of andrographolide permits it to penetrate the blood–brain barrier and concentrate in the brain, we hypothesized that andrographolide may be a potential chemotherapeutic agent for the treatment of glioblastomas. To clarify this point, we investigated the growth inhibitory effect and mechanisms of actions of andrographolide on human glioblastoma U251 and U87 cells.Main methodsMTT assay and trypan blue exclusion assay were used to investigate the proliferation inhibitory and cytotoxic effects of andrographolide, respectively. Cell cycle distribution was analyzed using flow cytometry. Apoptosis analysis proceeded by detecting the cleavage of caspase-3. The levels of proteins were probed by Western blotting.Key findingsThe results showed that non-toxic concentrations of andrographolide inhibited the proliferation of human glioblastoma cells through induction of G2/M arrest, which was accompanied by down-regulating Cdk1 and Cdc25C proteins. Additionally, andrographolide decreased the activity of PI3K/Akt signaling, as demonstrated by down-regulation of the expression of phos-PI3K, phos-Akt, phos-mTOR and phos-p70s6k in U251 and U87 cells. Furthermore, additive effects on the proliferation inhibition, G2/M arrest and down-regulation of G2/M phase-related proteins were observed, when a combined treatment of andrographolide with PI3K inhibitor LY294002 was used in U251 and U87 cells.SignificanceWe prove that andrographolide inhibits the proliferation of human glioblastoma cells via inducing G2/M arrest, which is mediated by inhibiting the activity of PI3K/Akt signaling.     

酿酒酵母产苹果酸的还原TCA路径构建及发酵调控

苹果酸广泛应用于食品、化工行业。文中通过在酿酒酵母内敲除丙酮酸脱羧酶PDC1,并通过构建胞质内还原TCA的路径,即超表达丙酮酸羧化酶和苹果酸脱氢酶,成功地实现了苹果酸的生产。在野生型菌株中基本检测不到苹果酸的生成,而在工程菌株,苹果酸发酵浓度达到了45 mmol /L,同时副产物乙醇的产量也降低了18%。进一步通过发酵调控提高第二信使Ca2+的浓度使苹果酸的产量提高了7 %,在此基础上提高丙酮酸羧化酶的辅酶生物素浓度,使苹果酸的产量达到52.5 mmol /L,较原始菌株提高了16%。     

低温下抗氧化酶活性与冬油菜根细胞结冰关系的初步研究

以4个抗寒性不同的油菜品种的根为材料,于低温试验箱内连续降温处理(4℃/24 h,0℃/24 h,-3℃/24 h,-6℃/24 h,-9℃/24 h,-15℃/24 h,-21℃/24 h),检测其抗氧化酶(POD、CAT)活性,并结合POD同工酶电泳和冷冻前后幼苗的形态变化特征,探讨油菜根部抗氧化酶活性变化与细胞冰冻状态间的相关性以及油菜根的抗冻机理.结果显示:(1)弱抗寒性油菜品种(‘临油7号’和Vision)在低温冷冻后,叶面出现大量水渍,之后叶片萎缩直至焦枯,根部出现水渍后软化直至干枯死亡;强抗寒性品种(‘陇油6号’和‘陇油8号’)在冷冻后不产生水渍或水渍极少,其根在冻后损伤也较轻微.(2)在连续冷冻条件下,弱抗寒性油菜根部POD和CAT活性在降温初期有较大幅度的变化,之后就保持恒定,说明根部细胞已完全结冰;而强抗寒性油菜根部POD和CAT活性在降温初期变化较小,后期持续大幅增加,表明根部细胞仍保持溶液状态;POD同工酶分析也反映出类似的变化规律.研究表明,低温下冬油菜根部抗氧化酶活性变化和细胞冰冻状态之间存在相关性;细胞结冰通常会给植物造成致死性伤害,强抗寒油菜品种能安全越冬的关键就是能通过某种机制避免细胞内结冰,其结冰温度越低,抗寒性越强.     

Dinuclear copper complexes of organic claw: potent inhibition of protein tyrosine phosphatases

Three dinuclear copper complexes of organic claw ligands (2,2′,2″,2?-(5-R-2-hydroxy-1,3-phenylene)bis(methylene)bis(azanetriyl)tetraacetic acid, R = methyl (H₅L1), chloro (H₅L2) and bromo (H₅L3)): [Cu₂NaL1(H₂O)₂] (1), [Cu₂HL2(H₂O)₂] (2), [Cu₂NaL3(H₂O)₂] (3), have been synthesized and characterized by elemental analyses, infrared spectra, thermo-gravimetric analyses, X-ray diffraction analysis, electrospray ionization mass spectra, pH-potentiometric titration, molar conductivity. Their inhibitory effects against human protein tyrosine phosphatase 1B (PTP1B), T cell protein tyrosine phosphatase (TCPTP), Megakaryocyte protein tyrosinephosphatase 2 (PTP-MEG2), srchomology phosphatase 1 (SHP-1) and srchomology phosphatase 2 (SHP-2) are evaluated in vitro. The three copper complexes exhibit potent and almost same inhibition against PTP1B and SHP-1 with IC₅₀ values ranging from 0.15 to 0.31 μM, about 2-fold stronger inhibition than against PTP-MEG2, 10-fold stronger inhibition than against TCPTP, but almost no inhibition against SHP-2. Kinetic analysis indicates that they are reversible competitive inhibitors of PTP1B. Molecular docking analyses confirm the inhibition model. Fluorescence titration studies suggest that the complexes bond to PTP1B with the formation of a 1:1 complex. The results demonstrate that copper complexes that are potent PTPs inhibitors but have different inhibitory effects over different PTPs, may be explored as new practical inhibitors towards individual PTP with some specificity.     

戊型肝炎病毒荧光定量RT-PCR快速检测技术的建立和初步应用

利用DNAMAN软件对GenBank登录的戊型肝炎病毒四个主要基因型代表株的序列进行分析, 选择其高度保守的ORF2区域设计合成引物和探针, 并用包含有扩增区域的核苷酸片段进行体外转录制备标准品cRNA。在对荧光定量RT-PCR的反应条件优化的基础上, 建立了适用于戊型肝炎病毒主要基因型检测的荧光定量RT-PCR检测技术。该检测技术可以有效检测I型和IV型戊型肝炎阳性病料, 而对猪的其它几种疫病阳性病料则为阴性结果, 证实本技术的特异性强、可靠性好。对阳性标准品的检测结果表明, 所建立的TaqMan荧光定量RT-PCR灵敏度可达2.0×101拷贝/反应, 相比于巢式RT-PCR方法, 其灵敏度高10~100倍以上。在对54份临床样品的检测中, 进一步证实了该方法快速、灵敏且重复性好, 可满足戊型肝炎病毒早期快速诊断的需要。     

Characteristics of cadmium accumulation and tolerance in <Emphasis Type="Italic">Rorippa globosa</Emphasis> (Turcz.) Thell., a species with some characteristics of cadmium hyperaccumulation

Characteristics of cadmium (Cd) accumulation and tolerance in Rorippa globosa (Turcz.) Thell., a species with some characteristics of cadmium hyperaccumulation were further investigated and compared with a closely related species, Rorippa islandica. The results showed that there was no phytotoxicity for R. globosa leaves or reduction in biomass when treated with 25 μg Cd g⁻¹, although the concentration of Cd accumulated in the leaves was up to 218.9 μg Cd g⁻¹ dry weight (DW). On the contrary, Cd toxicity was observed in R. islandica leaves by way of determining changes in fresh weight (FW), malondialdehyde (MDA) level and chlorophyll content while treated with 25 μg Cd g⁻¹ DW. R. globosa had stronger self-protection ability than R. islandica to adapt to oxidative stress caused by Cd. Application of Cd significantly increased the activity of superoxide dismutase (SOD) in leaves, the activity of peroxidase (POD) in roots, and the activity of catalase (CAT) in leaves and roots of R. globosa. By contrast, in R. islandica, the activity of antioxidant enzymes was inhibited or unchanged by various Cd treatments. However, R. globosa leaves had higher activity of antioxidant enzymes such as SOD and POD than that of R. islandica. The antioxidative defense systems in R. globosa might play an important role in Cd tolerance. The Cd treatments significantly induced the synthesis of phytochelatins (PCs) in the two species. Leaf PCs and Cd accumulation by R. globosa were much greater than those by R. islandica, but root PCs and Cd accumulation by R. islandica were much greater than those by R. globosa, suggesting that PCs in leaves may be a biomarker of Cd hyperaccumulation, and the synthesis of PCs may be related to an increase in the uptake of Cd ions into the cytoplasm, not the primary mechanism for Cd tolerance.     

不同抗性苹果品种应答轮纹病菌胁迫的差异蛋白质组分析

为鉴定不同抗性苹果(Malus domestica)品种响应轮纹病菌胁迫的抗性相关蛋白表达差异, 以抗病品种华月及易感品种金冠为试材, 采用高通量同位素标记定量(IBT)技术结合液相色谱-串联质谱(LC-MS)鉴定技术, 对病原菌处理前后抗、感病品种叶片的蛋白质组差异表达进行分析, 共鉴定出171个差异表达蛋白(DEPs)。GO富集及KEGG通路分析表明, 在细胞组分、分子功能和生物过程3类中共注释到686个GO条目, 其中52个DEPs注释于KEGG通路的18个显著差异途径(P<0.05)。亚细胞定位预测分析表明, 171个DEPs中有170个分别定位于8类细胞器。蛋白功能注释分析表明, 46个DEPs注释于7类抗性相关蛋白, 包括类甜蛋白、过氧化物酶、多酚氧化酶、过敏原蛋白、几丁质酶、内切葡聚糖酶以及主乳胶蛋白。此外, 还对抗性相关蛋白的表达特点及基因定量结果进行了分析。该研究结果可为进一步解析抗、感病苹果品种应答轮纹病菌胁迫的抗性机制提供参考。