红树林植物木果楝细胞毒活性和化学成分研究

本研究采用MTT法对红树林植物木果楝(Xylocarpus grantum)正己烷提取物进行细胞毒活性筛选,结果显示对宫颈癌Hela细胞有较强的生长抑制活性。为了确定其中的活性成分,利用GC/MS法对正己烷提取物的化学成分进行分析,共鉴定了17种成分,大部分为有机酸类化合物。其中油酸(Oleic acid,24.89%)、棕榈酸(Palmitic acid,24.82%)和亚油酸(Linoleic acid,16.86%)为主要成分,据文献报道亚油酸具有肺腺癌细胞生长抑制活性。     

数种农药对蚕豆根腐病的田间防效

在实验室内探讨了三唑酮,甲基硫菌灵,福美双,恶霜灵和甲霜灵等5种杀菌剂单用或混用对蚕豆种子萌发和幼苗生长的影响,据此,在田间开展了杀菌剂拦种和杀菌剂与杀虫剂混用防治蚕豆根腐病的研究,第1年的结果表明,在11个处理中,三唑酮单独拌和效果最为显著,与对照相比,在0.01ga.i.kg^_1种子的剂量下,使6周龄植株的根腐病指数降低51.5%,成株累计死亡率减少36%,单株种子产量提高21%,每公顷种子产量增加97.6%,其他处理未取得显著防效,第2年开展的三唑酮拌种是防治蚕豆根腐病的有效措施之一。但杀菌拌种应与其他防治措施综合应用,方可取得更好的防治效果。     

烟夜蛾和棉铃虫对高浓度烟草挥发物的电生理和行为反应

寡食性的烟夜蛾Helicoverpa assulta (Guenée)和广食性的棉铃虫H. armigera (Hübner)是夜蛾属Heliothis的两近缘种昆虫。主要的农作物中,棉花和番茄上极少发现烟夜蛾,而辣椒上几乎没有棉铃虫,只有烟草均为二者所嗜食,也唯独在烟草上它们可以稳定共存。为明确植物挥发物对昆虫寄主定向和选择行为的影响,本文运用触角电位（EAG）和风洞技术,测定了两种夜蛾的处女雌蛾、交配雌蛾及雄蛾对20种高浓度（0.1 mol/L）烟草挥发物的电生理和行为反应。结果表明：烟夜蛾和棉铃虫对测试的烟草挥发物均可产生EAG反应,而且都表现出绿叶气味＞脂类和芳香化合物＞单萜、倍半萜和杂环化合物的总体反应趋势;两种夜蛾对多数化合物的EAG反应既无显著的种内性别差异,也无显著的种间差异,表明二者嗅觉神经系统对寄主气味图谱的识别和感受能力具有一定的相似性,可对寄主植物的化学信息产生相同的“理解”;二者的行为反应结果与EAG反应结果基本一致,即两种夜蛾受到的嗅觉刺激与产生的行为反应具有统一性,结合两种夜蛾寄主范围的差异,推测烟草挥发物主要影响两种夜蛾的寄主定向行为,而寄主选择行为可能更依赖于二者与植物接触后对植物理化性质的评价过程。     

Protein structure and import into the peroxisomal matrix

Proteins destined for the peroxisomal matrix are synthesized in the cytosol, and imported post-translationally. It has been previously demonstrated that stably folded proteins are substrates for peroxisomal import. Mammalian peroxisomes do not contain endogenous chaperone molecules. Therefore, it is possible that proteins are required to fold into their stable, tertiary conformation in order to be imported into the peroxisome. These investigations were undertaken to determine whether proteins rendered incapable of folding were also substrates for import into peroxisomes. Reduction of albumin resulted in a less compact tertiary structure as measured by analytical centrifugation. Microinjection of unfolded albumin molecules bearing the PTS1 targeting signal resulted in their import into peroxisomes. Kinetic analysis indicated that native and unfolded molecules were imported into peroxisomes at comparable rates. While import was unaffected by treatment with cycloheximide, hsc70 molecules were observed to be imported along with the unfolded albumin molecules. These results indicate that proteins, which are incapable of assuming their native conformation, are substrates for peroxisomal import. When combined with previous observations demonstrating the import of stably folded proteins, these results support the model that tertiary structure has no effect on protein import into the peroxisomal matrix .     

原肌球蛋白相关激酶B在肿瘤中的研究进展

原肌球蛋白相关激酶B(tropomyosin-related kinase B,TrkB)是一种神经营养性酪氨酸受体激酶,通过介导丝裂原活化蛋白激酶(mitogen-activated protein kinases,MAPK)、磷脂酶C-γ(phospholipase C-γ,PLC-γ)、磷脂酰肌醇3-激酶(pho...     

In Vitro DNA Tethering of HIV-1 Integrase by the Transcriptional Coactivator LEDGF/p75

Although LEDGF/p75 is believed to act as a cellular cofactor of lentiviral integration by tethering integrase (IN) to chromatin, there is no good in vitro model to analyze this functionality. We designed an AlphaScreen assay to study how LEDGF/p75 modulates the interaction of human immunodeficiency virus type 1 IN with DNA. IN bound with similar affinity to DNA mimicking the long terminal repeat or to random DNA. While LEDGF/p75 bound DNA strongly, a mutant of LEDGF/p75 with compromised nuclear localization signal (NLS)/AT hook interacted weakly, and the LEDGF/p75 PWWP domain did not interact, corroborating previous reports on the role of NLS and AT hooks in charge-dependent DNA binding. LEDGF/p75 stimulated IN binding to DNA 10-fold to 30-fold. Stimulation of IN-DNA binding required a direct interaction between IN and the C-terminus of LEDGF/p75. Addition of either the C-terminus of LEDGF/p75 (amino acids 325-530) or LEDGF/p75 mutated in the NLS/AT hooks interfered with IN binding to DNA. Our results are consistent with an in vitro model of LEDGF/p75-mediated tethering of IN to DNA. The inhibition of IN-DNA interaction by the LEDGF/p75 C-terminus may provide a novel strategy for the inhibition of HIV IN activity and may explain the potent inhibition of HIV replication observed after the overexpression of C-terminal fragments in cell culture.     

红树植物内生真菌Penicillium sp.的化学成分

应用各种层析手段,从红树植物内生真菌GT26158菌丝体的甲醇提取物中分离纯化了7个含氮化合物,结合多种波谱方法(ESI-MS,1D-NMR,2D-NMR),它们被鉴定为2′-deoxyuridine(1)、thymidine(2)、2′-deoxyad-enosine(3)、cyclo(tyrosyl-phenylalanyl,4)、serine(5),cyclo(seryl-tryptophyl,6)、alanine(7)。     

长裙竹荪正己烷提取物化学组成及抑菌活性研究

以正己烷为溶剂,对长裙竹荪子实体进行索氏提取,提取率为1.36%。应用GC-MS对提取物的化学成分进行分析,Rxi-1ms柱分离,质谱解析鉴定出55种成分,其中23种成分是首次从竹荪属中检测出来,其主要成分为:羧酸、醇、酮、倍半萜、芳香烃、酯等。提取物对伤寒杆菌、金黄色葡萄球菌、变形杆菌和枯草芽孢杆菌有很好的抑制作用。     

不同坡向高寒草甸土壤理化特性和微生物数量特征

阐明不同坡向草地土壤性质的空间分异格局,为退化草地的精准修复和科学管理提供参考。研究了青藏高原东缘高寒草甸退化草地不同坡向(北坡N、西北坡NW、西坡W、东坡E、东北坡NE、西南坡SW和南坡S)土壤理化性质和微生物数量特征。结果发现:从N→S坡向上,土壤有机质、碳氮比和全氮含量均呈下降趋势,土壤全磷含量和pH值在不同坡向间均无显著差异(P0.05),E坡向全磷含量最高((2.83±0.95)g/kg),NW坡向含量最低((2.07±0.12)g/kg);土壤细菌、真菌和放线菌数量变化呈波动现象,NW坡向的细菌((13.0×10~5±1.0×10~5)个/g)、真菌((14.0×10~3±0.0)个/g)和放线菌((24.0×10~4±1.0×10~4)个/g)数量最低,E坡向的细菌数量最高((85.5×10~5±2.5×10~5)个/g),S坡向的真菌((24.0×10~3±0.0)个/g)和放线菌((209.5×10~4±4.5×10~4)个/g)数量最高;回归分析表明,在E→S坡向上,随土壤含水量、有机质、碳氮比和全氮含量的增加,土壤细菌和放线菌数量均显著降低(P0.05),而土壤真菌数量随含水量、pH值、土壤养分含量的增加略有降低(P0.05)。可见,不同坡向高寒草甸土壤理化特征差异明显,也导致了土壤微生物数量分配格局的不同。