Plasticity of the differentiated state

Heterokaryons provide a model system in which to examine how tissue-specific phenotypes arise and are maintained. When muscle cells are fused with nonmuscle cells, muscle gene expression is activated in the nonmuscle cell type. Gene expression was studied either at a single cell level with monoclonal antibodies or in mass cultures at a biochemical and molecular level. In all of the nonmuscle cell types tested, including representatives of different embryonic lineages, phenotypes, and developmental stages, muscle gene expression was induced. Differences among cell types in the kinetics, frequency, and gene dosage requirements for gene expression provide clues to the underlying regulatory mechanisms. These results show that the expression of genes in the nuclei of differentiated cells is remarkably plastic and susceptible to modulation by the cytoplasm. The isolation of the genes encoding the tissue-specific trans-acting regulators responsible for muscle gene activation should now be possible.     

苦楝果实中化学成分进一步研究及生物活性测定

采用生物活性追踪法,从苦楝果实中分离得苦楝新醇(Ⅰ)、苦楝酮(Ⅱ)、苦楝醇(Ⅲ)、苦楝二醇(Ⅳ)、苦楝三醇(Ⅴ)、香草酸(Ⅵ)、香草醛(Ⅶ)和川楝素(Ⅷ),并根据波谱(1R,MS,′H—NMR,~(13)C—NMR)分析和理化常数测定确定其结构.其中Ⅱ、Ⅲ、Ⅳ和Ⅴ的21—H存在差向异构现象.生测结果表明,Ⅱ～Ⅴ和Ⅷ对菜青虫(Pieris rapae)有明显的拒食活性,Ⅷ还表现出明显的胃毒活性;Ⅰ、Ⅳ和Ⅶ仅表现出一定的拒食活性.     

Chemical transformations in individual ultrasmall biomimetic containers

Individual phospholipid vesicles, 1 to 5 micrometers in diameter, containing a single reagent or a complete reaction system, were immobilized with an infrared laser optical trap or by adhesion to modified borosilicate glass surfaces. Chemical transformations were initiated either by electroporation or by electrofusion, in each case through application of a short (10-microsecond), intense (20 to 50 kilovolts per centimeter) electric pulse delivered across ultramicroelectrodes. Product formation was monitored by far-field laser fluorescence microscopy. The ultrasmall characteristic of this reaction volume led to rapid diffusional mixing that permits the study of fast chemical kinetics. This technique is also well suited for the study of reaction dynamics of biological molecules within lipid-enclosed nanoenvironments that mimic cell membranes.     

紫背金盘提取物对小菜蛾的作用研究

紫背金盘提取物对小菜蛾幼虫有拒食和生长发育抑制活性，以氯仿提取物活性为最高。饲喂处理幼虫出现脱肛，黑斑和畸形等缓慢症状，成虫的生殖过程受到影响，这种作用有利于压低田间种群数量。对多种杀虫剂产生抗性的小菜蛾品系对紫背金盘提取物没有抗性，因此，这种植物提取物可作为小菜蛾抗性治理的一条途径。     

几丁质合成抑制剂类杀虫剂的发展和应用

本文重点介绍了苯酰基脲类、噻嗪酮这两类几丁质合成抑制剂类杀虫剂的发展概况和应用的有关杀虫特性及其目前在防治几类农作物害虫方面的应用情况,分析了其在应用方面的主要问题,并对其前景进行了讨论。     

楝属川楝素含量与生物活性的关系

本文报道用高速液相色谱测定了川楝素含量的各地楝树样品水提物及几种川楝素产品对菜青虫的生物活性,讨论了川楝素含量与生物活性的关系。叶、果样品中虽不含或仅含少量川楝素,但对试虫仍表现出一定的活性。皮中含有较丰富的川楝素,其含量与拒食活性呈正相关,但与毒效作用不相关。四川样品川楝素含量及生物活性均很高而值得重视。川楝素粗产品相对于纯川楝素而言对试虫具更高的生物活性。这种川楝素含量与活性的非线性关系说明样品中其它成份也具活性或与川楝素有着协同作用。通过测定、分析和讨论,指出用川楝素粗产品防治菜青虫是一经济、有效,可行的措施。文中应用了评判援效型杀虫剂的新方法,供讨论和参考。     

Effects of Antrodia camphorata on alcohol clearance and antifibrosis in livers of rats continuously fed alcohol

Alcoholic fatty liver disease (AFLD) is the result of an excessive or chronic consumption of alcohol. Nine male Wistar rats per group were randomly assigned to one of the following drinking treatments: a 20% (w/w) alcohol solution (ALC); a 20% (w/w) alcohol solution cotreated with 0.25 g silymarin/kg BW/day; or a 20% (w/w) alcohol solution cotreated with 0.025 g Niuchangchih ( Antrodia camphorata )/kg BW/day for 4 weeks. Rats with cotreatments of silymarin or Niuchangchih had smaller (p < 0.05) relative liver size, less (p < 0.05) liver lipid accumulation, and lower (p < 0.05) liver damage indices [aspartate aminotransferase (AST) and alkaline phosphatase (ALP) values]. In the regulation of alcohol metabolism, the lower serum alcohol level was observed only in alcohol-fed rats supplemented with Niuchangchih. Meanwhile, cotreatment of silymarin or Niuchangchih increased (p < 0.05) CAT and ALDH activities but did not (p > 0.05) affect ADH and CYP2E1 expressions, which accelerate alcohol metabolism in the body. Additionally, neither silymarin nor Niuchangchih (p > 0.05) influenced serum/hepatic MMP-2 activities and NF-κB, AP1, and α-SMA gene expressions, but serum/hepatic MMP-9 activities and TNF-α, KLF-6, and TGF-β1 gene expressions of alcohol-fed rats were down-regulated (p < 0.05) by silymarin or Niuchangchih, which also could explain the lower liver damage observed in rats chronically fed alcohol.     

Identification and anti-human glioblastoma activity of tagitinin C from Tithonia diversifolia methanolic extract

The Tithonia diversifolia methanolic extract (TDM), which showed antiproliferative activity against human glioblastoma U373 cells, with an IC50 value of 59.2±3.7 μg mL(-1), was passed through silica gel chromatography and successively eluted with different percentages of EtOAc/hexane. The 10-60% EtOAc/hexane subfractions, which exhibited a comparatively higher antiproliferative activity, were isolated, and then structural identification was proceeded with 1H nuclear magnetic resonance. The isolated compound was tagitinin C, a kind of sesquiterpenoid. The IC50 value was 6.1±0.1 μg mL(-1) in U373 treated with tagitinin C. In flow cytometric analysis and inhibition of pan-caspase, the results showed that the anti-glioblastoma effect was apoptosis-independent. In PARP, p-p38, ULK1, and LC3-II expression, the anti-glioblastoma induced by tagitinin C was likely via autophagy. In the ULK1 siRNA transfection experiment, autophagy blockade counteracted the suppression induced by tagitinin C. The result suggested that tagitinin C induces U373 cell death dependent upon autophagy under certain conditions.     

Derivation and properties of recombinant Fab antibodies to coplanar polychlorinated biphenyls

Recombinant Fab antibodies (rFabs) specific for coplanar polychlorinated biphenyls (PCBs) were derived from a hybridoma cell line (Chiu et al. Anal. Chem. 1995, 67, 3829-3839). Immunoglobulin V(H)-C(H1) and V(L)-C(L) sequences from S2B1 messenger RNA were amplified by PCR and cloned into the M13 phagemid vector pComb3H. Phage displaying rFab were enriched by panning on a PCB hapten conjugate and expressed as soluble rFabs in Escherichia coli XL-1 Blue. Two rFab clones competitively bound PCBs 77 and 126 with half-maximal inhibition (I(50)) of 10-13 ppb in indirect and direct enzyme immunoassays (EIAs), with selectivity nearly identical to that of whole S2B1 IgG and its Fab fragments prepared by papain digestion. These results, and comparison of N-terminal amino acid sequences of MAb S2B1 and the rFab, indicated that rFab S2B1 is a functional copy of the MAb. The rFab S2B1 sequences have 75-89% sequence identity with antibodies that bind nitrophenyl haptens and are being used to construct a three-dimensional computational model of the PCB binding site.     

一种病毒抑制物质NS-83的研制及其对番茄预防TMV初侵染的研究

 本文论述了几种长链醇和长链酸,在番茄上对TMV初侵染的抑制作用。测试了壬醇、癸醇、十一(烷)醇、十二(烷)醇、十四醇、十六醇、十八醇等长链醇。试验的脂肪酸有二十二酸、二十二酸钠、混合脂肪酸和NS-83制剂。菜籽油中的脂肪酸含有1.1%二十二酸、35~36%顺-二十二烯-13酸(芥酸)、11~12%花生酸、12.4~12.7%亚麻酸、12.7~12.9%亚油酸、11~11.3%油酸、2.5%二十四烯酸、2%花生烯酸、4%木焦油酸、1.8~2%硬脂酸和3.1%软脂酸。这些脂肪酸的混合剂对侵染番茄的TMV的抑制作用与纯二十二酸单独的抑制作用相接近。NS-83制剂是由混合脂肪酸制备,防病效果更好,与目前其他一些抑制物质相比较,成本低廉,可用于防治番茄病毒病。此外,这种抑制物质似具有诱导番茄对TMV的初侵染以及对TMV和CMV产生耐病性的能力。其实际效果的机理,有待进一步试验,加以证明。