长日照处理对牵牛开花抑制作用研究 Ⅱ.光周期处理与牵牛花芽分化及基因活动的关系

单个光周期暗期长度短于12h时,牵牛植株营养生长旺盛,开花受到抑制,并且出现了诱导光周期处理（ISD）子叶中没有的二种蛋白质或多肽（pI4.1,MW16.5kD;pI4.2,MW16．5kD）。连续光照处理（ICL）子叶内出现了短日照处理（ISD）子叶内没有的体外翻译蛋白质分子量为17．4kD的Poly（A~ ）mRNA。牵牛子叶内的这些变化可能与抑制牵牛花芽分化有一定的关系。     

Co-administration of APD668, a G protein-coupled receptor 119 agonist and linagliptin,a DPPIV inhibitor,prevents progression of steatohepatitis in mice fed on a high trans-fat diet

Non-Alcoholic SteatoHepatitis (NASH) is the more severe form of Non-Alcoholic Fatty Liver Disease (NAFLD) and is characterized by the presence of hepatic steatosis, oxidative stress, inflammation, hepatocyte injury with or without fibrosis. Recently, GPR119 receptor has emerged as a novel therapeutic target for the treatment of dyslipidemia and non-alcoholic steatohepatitis. In the present study, we investigated the effect of APD668, a GPR119 agonist alone or in combination with linagliptin, a DPPIV inhibitor on the progression of steatohepatitis in mice fed on a high trans-fat diet. In this study, monotherapy with either APD668 or linagliptin caused a reduction in the levels of ALT, AST, glucose, cholesterol and epididymal fat mass but the effect was more pronounced upon treatment with combination of both drugs.On the other hand, combined treatment of APD668 with linagliptin demonstrated a non-significant additive effect in reduction of hepatic triglyceride (?78%) and cholesterol (?56%) compared to monotherapy groups. Moreover, co-administration of APD668 and linagliptin resulted in enhanced levels of active GLP-1 with additional benefit of significant synergistic decrease in body weight gain (?19%) in mice. We speculated that the enhanced effect observed with the combination treatment could be due to either 1) direct activation of GPR119 receptors present in liver and intestine or 2) enhanced active GLP-1 levels or 3) decreased degradation of GLP-1 in-vivo through DPPIV inhibition. Therefore, these findings clearly suggest that GPR119 receptor agonists in combination with DPPIV inhibitors may represent a promising therapeutic strategy for the treatment of non-alcoholic steatohepatitis.     

Xylarianins A-D from the endophytic fungus Xylaria sp. SYPF 8246 as natural inhibitors of human carboxylesterase 2

Eighteen secondary metabolites were isolated from the fermentation broth of the endophytic fungus Xylaria sp. SYPF 8246, including four new compounds, xylarianins A-D (1–4), three new natural products, 6-methoxycarbonyl-2′-methyl-3,5,4′,6′-tetramethoxy-diphenyl ether (5), 2-chlor-6-methoxycarbonyl-2′-rnethyl-3,5,4′,6′-tetramethoxy-diphenyl ether (6), and 2-chlor-4′-hydroxy-6-methoxy carbonyl-2′-methyl-3,5,6′-trimethoxy-diphenyl ether (7), and eleven known compounds (8–18). Their structural elucidations were conducted by using 1D and 2D NMR, HRESIMS, and Rh₂(OCOCF₃)₄-induced electronic circular dichroism (ECD) spectra analyses. The integrated ¹H and ¹³C NMR data of three new natural products 5–7 were reported for the first time. All the isolated compounds were assayed for their inhibitory activities against human carboxylesterase 2 (hCE 2). Compounds 1, 5–9, and 18 displayed significant inhibitory activities against hCE 2 with IC₅₀ values of 10.43 ± 0.51, 6.69 ± 0.85, 12.36 ± 1.27, 18.25 ± 1.78, 29.78 ± 0.48, 18.86 ± 1.87, and 20.72 ± 1.51 µM, respectively. The interactions between compounds 1 and 5 with hCE 2 were anaylzed by molecular docking.     

抑制西瓜蔓枯病菌的生防真菌筛选、鉴定及发酵条件优化

筛选对西瓜蔓枯病菌具有抑制作用的生防真菌,优化其发酵条件以提升发酵液抑菌效果。以平板对峙试验和摇瓶培养抑菌试验筛选拮抗真菌;根据形态学特征和18S rDNA序列分析进行菌株鉴定;通过扫描电镜观察对西瓜蔓枯病菌的寄生作用,以单因素试验和响应曲面法确定其最适发酵条件,在此基础上,通过盆栽试验研究其防病效果。结果表明:在所筛选到的9株生防真菌中M1菌株的抑菌率最高,其形态学特征与烟管菌(Bjerkandera adusta)相符,18S rDNA序列分析显示其与烟管菌在系统发育树上聚在一支,因此将菌株M1鉴定为黑管菌属(Bjerkandera)、烟管菌。在扫描电镜下观察到烟管菌能够直接穿透西瓜蔓枯病菌菌丝,对其发酵条件优化后确定了最佳条件组合:C/N为7.1,pH为7.4,装瓶量为44%,时间为19d,转速为180r/min,温度为29℃,在此条件下抑菌率为52.64%,高于未经优化的抑菌率。温室盆栽中对西瓜蔓枯病菌的防病效果达到74.3%,高于多菌灵处理。烟管菌作为生防真菌对西瓜蔓枯病菌具有较好的抑制作用,条件优化后进一步提升了抑菌效果,在生物防治中具有巨大应用潜力。     

Purification and characterization of the sunflower seed (Helianthus annuus L.) major aminopeptidase

The sunflower seed (Helianthus annuus L.) major peptidase was purified to molecular homogeneity. It is an 80 kDa enzyme with pI of 4.6 and optimal activity at pH 7.5–8.0 and 45–50°C. It is a thiol-dependent aminopeptidase hydrolyzing peptides in a step-by-step manner as cleaving after the N-terminal amino acid residue of the substrate. It requires substrate acyl parts with a free amino group in either α- or β-position and l-configuration of the adjacent carbon atom. The enzyme prefers amino acid residues with bulky hydrophobic side chains at P₁-position and its catalytic efficacy is affected by the structure of both P₁ and P₁′ parts of the substrate.     

乳酸杆菌发酵滤液对人宫颈癌细胞株Hela细胞的抑制作用

目的观察乳酸杆菌DM9811发酵滤液及其主要成分对宫颈癌细胞株Hela细胞的体外增殖的影响,探索乳酸杆菌发酵滤液对宫颈癌细胞是否有抑制作用及解析作用的有效成分。方法用MTr法研究不同浓度乳酸杆菌DM9811发酵滤液在不同时间对Hela细胞的抑制作用,在此基础上研究脂肪酸、菌体核酸在不同时间对Hela细胞的抑制作用。结果不同浓度乳酸杆菌DM9811发酵滤液及相关物质在不同时间对Hela细胞的抑制作用显示：（1）乳酸杆菌DM9811发酵滤液各浓度组对Hela细胞的生长均有抑制作用,且这种抑制作用呈剂量-时间依赖方式。24、48、72h达到半数抑制率的发酵滤液浓度分别为8．9％、5．3％、3．8％。（2）乳酸杆菌DM9811发酵滤液脂肪酸对Hela细胞的生长有一定抑制作用,抑制率在7．0％～34．0％。（3）乳酸杆菌DM9811菌体核酸对Hela细胞的生长有抑制作用,抑制率为9．7％-53．4％,呈剂量一时间依赖方式。72h达到半数抑制率核酸的浓度为5．5μg/ml。结论乳酸杆菌DM9811发酵滤液对Hela细胞的生长具有显著的抑制作用,其中脂肪酸组分是有效成分之一。     

Immunosuppressive Withanolides from Withania coagulans

Six new withanolides, withacoagulins A–F ( 1 – 6 , resp.), together with ten known withanolides, 7 – 16 , were isolated from the aerial parts of Withania coagulans. Their structures were determined by spectroscopic techniques including 1D‐ and 2D‐NMR (¹H, ¹³C, HMQC, and HMBC) and MS experiments. These compounds, including the crude extracts of this herb, exhibited strong inhibitory activities on the T‐ and B‐cell proliferation.     

鼠尾藻对赤潮异弯藻和中肋骨条藻的抑制作用

通过共培养的方法,研究了鼠尾藻（Surgassum thunbergii）培养水的过滤液、新鲜组织、干粉末、水溶性抽提液对赤潮异弯藻（Heterosigma akashiwo）和中肋骨条藻（Skeletonema costatum）生长的抑制效应,建立了分隔共培养系统并证明了抑制物质的存在,排除了细胞直接接触抑制的可能性.结果表明,在共培养实验中,鼠尾藻新鲜组织、干粉末及水溶性抽提液对赤潮异弯藻和中肋骨条藻的生长具有显著的抑制作用,且在较高浓度下对两种赤潮微藻的生长具有致死效应.在一次性及半连续培养方式下,鼠尾藻培养水过滤液对赤潮异弯藻的生长无抑制效应,而对中肋骨条藻的生长具有显著的抑制效应.     

Syntheses, structures and bioactivities of silver(I) complexes with dithioether ligands that contain a di- or triethylene glycol chain and different terminal groups

A series of flexible dithioethyl ligands that contain ethyleneoxy segments were designed and synthesized, including bis(2-(pyridin-2-ylthio)ethyl)ether (L¹), 1,2-bis(2-(pyridin-2-ylthio)ethoxy)ethane (L²), bis(2-(benzothiazol-2-ylthio)ethyl)ether (L³) and 1,2-bis(2-(benzothiazol-2-ylthio)ethoxy)ethane (L⁴). Reactions of these ligands with AgNO₃ led to the formation of four new supramolecular coordination complexes, [Ag₂L¹(NO₃)₂]₂ (1), [Ag₂L²(NO₃)₂] (2), [AgL³(NO₃)]_∞ (3) and [AgL⁴(NO₃)] (4) in which the length of the (CH₂CH₂O)_n spacers and the terminal groups of ligands cause subtle geometrical differences. Studies of the inhibitory effect to the growth of Phaeodactylum tricornutum show that all four complexes are active and the compound 4 has the highest inhibitory activity.     

Antimicrobial and antibiofilm activity of pleurocidin against cariogenic microorganisms

Dental caries is a common oral bacterial infectious disease of global concern. Prevention and treatment of caries requires control of the dental plaque formed by pathogens such as Streptococcus mutans and Streptococcus sobrinus. Pleurocidin, produced by Pleuronectes americanus, is an antimicrobial peptide that exerts broad-spectrum activity against pathogenic bacteria and fungi. Moreover, pleurocidin shows less hemolysis and is less toxic than other natural peptides. In the present study, we investigated whether pleurocidin is an effective antibiotic peptide against common cariogenic microorganisms and performed a preliminary study of the antimicrobial mechanism. We assayed minimal inhibitory concentration (MIC), minimal bactericide concentration (MBC) and bactericidal kinetics and performed a spot-on-lawn assay. The BioFlux system was used to generate bacterial biofilms under controllable flow. Fluorescence microscopy and confocal laser scanning microscopy (CLSM) were used to analyze and observe biofilms. Scanning electron microscopy was used to observe the bacterial membrane. MIC and MBC results showed that pleurocidin had different antimicrobial activities against the tested oral strains. Although components of saliva could affect antimicrobial activity, pleurocidin dissolved in saliva still showed antimicrobial effects against oral microorganisms. Furthermore, pleurocidin showed a favorable killing effect against BioFlux flow biofilms in vitro. Our findings suggest that pleurocidin has the potential to kill dental biofilms and prevent dental caries.