Molecular mimicry regulates ABA signaling by SnRK2 kinases and PP2C phosphatases

Abscisic acid (ABA) is an essential hormone for plants to survive environmental stresses. At the center of the ABA signaling network is a subfamily of type 2C protein phosphatases (PP2Cs), which form exclusive interactions with ABA receptors and subfamily 2 Snfl-related kinase (SnRK2s). Here, we report a SnRK2-PP2C complex structure, which reveals marked similarity in PP2C recognition by SnRK2 and ABA receptors. In the complex, the kinase activation loop docks into the active site of PP2C, while the conserved ABA-sensing tryptophan of PP2C inserts into the kinase catalytic cleft, thus mimicking receptor-PP2C interactions. These structural results provide a simple mechanism that directly couples ABA binding to SnRK2 kinase activation and highlight a new paradigm of kinase-phosphatase regulation through mutual packing of their catalytic sites.     

RNAi沉默转基因油菜fad2基因表达的种子特异性分析

为研究RNAi沉默转基因油菜fad2基因表达的效果及其器官特异性,实时荧光定量PCR法分析比较了转基因油菜W-4与非转基因对照Westar开花后第7天、第14天、第21天、第28天的种子以及越冬期油菜根、茎、叶器官中的fad2基因的相对表达量。结果显示:对照Westsr种子中fad2基因的相对表达量随开花后的天数呈逐渐增加的趋势,但W-4种子中fad2基因的相对表达量在开花后第21天、第28天较对照Westar显著下降,降幅达到60%。说明转基因油菜W-4在种子发育过程中表达的fad2基因的dsRNA干扰了fad2基因表达。W-4与Westar在越冬期根、茎、叶器官中fad2基因的相对表达量基本一致,无显著性差异。脂肪酸组成分析结果显示:W-4种子中油酸平均含量达到81.5%较Westar增加了近15%,而多不饱和脂肪酸平均含量为5.25%,较Westar下降了近70%;但根、茎、叶中的脂肪酸含量二者无显著差异;结果表明转基因油菜中RNAi干扰fad2基因表达具有种子特异性,不干扰其它器官的fad2基因表达。研究还发现转基因油菜fad2基因表达下降的时期与napin基因表达时期同步,均始于开花后21d左右,表明目标基因的表达受napin启动子的准确控制。     

Preparation and evaluation of self-microemulsifying drug delivery system of baicalein

The main object of this work is to prepare self-microemulsifying drug delivery system (SMEDDS) for oral bioavailability enhancement of a poorly water-soluble drug, baicalein. SMEDDS is the mixture of surfactants, cosurfactants, and oils, which are emulsified in aqueous media under conditions of gentle agitation or gastrointestinal motility. Solubility of baicalein was determined in various vehicles. Pseudo-ternary phase diagrams were constructed to identify the efficient self-emulsification region and droplet size distributions of the resultant microemulsions were determined using a particle size analyzer. Optimized SMEDDS formulations for baicalein were Cremophor RH40 (53.57%) as surfactant, Transcutol P (21.43%) as cosurfactant, and Caprylic capric triglyceride (ODO, 25%) as oil. The drug release rate of SMEDDS was significantly higher than that of the baicalein suspension. Comparison of the pharmacokinetics between baicalein-loaded SMEDDS and baicalein suspension was also performed in rats. The plasma concentrations of baicalein and baicalin, its mainly conjugated metabolite, were determined by HPLC method. The in vivo results showed that the absorption of baicalein from SMEDDS resulted in about 200.7% increase in relative bioavailability compared with that of the baicalein suspension. Our studies illustrated the potential use of SMEDDS for the delivery of hydrophobic compounds, such as baicalein by the oral route.     

岳阳城区垂直绿化现状及植物材料选择

在对岳阳市绿化及垂直绿化现状地调查的基础上,分析了岳阳城区垂直绿化存在的主要问题,总结了已运用的主要垂直绿化模式,并初步提出岳阳城区开展垂直绿化的主要植物种类及配置原则与建议。     

百脉根根瘤菌自体诱导物合成酶基因mrlI2的初步研究

许多细菌均能产生一类叫做自体诱导物的信号分子,用于感知自身密度的变化,从而调控其生理行为,这种现象称为群体感应[1]。越来越多的研究表明,在根瘤菌中普遍存在着群体感应调控系统[2],并且它可能在根瘤菌与豆科植物共生结瘤固氮过程中起着重要作用。目前,在豌豆根瘤菌中共发现有4种群体感应系统(rai,rhi,cin和tra),其中cin系统位于上游,起总调控作用,tra系统控制着质粒的转移,rhi系统与结瘤数量有关,rai系统的功能还不清楚,它们共同组成了一个复杂的群体感应调控系统[3]。在苜蓿中华根瘤菌中,也发现群体感应系统与根瘤菌的生长和结瘤效率有关[4]。对中慢生型华癸根瘤菌和天山根瘤菌的研究     

红锥扦插繁殖试验

红锥是我省重要的乡土阔叶树种,也是优良的用材树种。从2002-2004年设置了生根促进剂、容器、扦插时间及处理穗条的扦插比较试验,结果表明:红锥扦插生产宜在夏秋两季开展;选用半木质化穗条,用黄心土作基质,以5 cm×12 cm白色塑料袋作容器;穗条扦插前采用10%酒精溶液浸泡处理可获得较高的成活率。但激素对成活率的影响还需进一步开展研究。     

龙脑香科树种引种育苗技术研究

2002年从泰国和越南引进缠结龙脑香、蛇羯布罗香、小瘤龙脑香、具翼龙脑香、钝叶娑罗双、泰国娑罗双和香坡垒等7种龙脑香科树种,对种子的采集、处理、运输、播种育苗等开展了系列研究。结果表明：不同的树种种子保存条件和时间差别很大,发芽率差异明显,最高的发芽率可达100%,最低的为27%;在广州地区,苗木能在自然条件下正常生长发育,且生长较快,生长量普遍超过用作对照的乡土阔叶树种木荷和香樟,且苗木健壮、生机旺盛,特别能忍受干旱的环境和气候条件,具有良好的开发利用前景。     

Marine Antitumor Peptide Dolastatin 10: Biological Activity,Structural Modification and Synthetic Chemistry

Dolastatin 10 (Dol-10), a leading marine pentapeptide isolated from the Indian Ocean mollusk Dolabella auricularia, contains three unique amino acid residues. Dol-10 can effectively induce apoptosis of lung cancer cells and other tumor cells at nanomolar concentration, and it has been developed into commercial drugs for treating some specific lymphomas, so it has received wide attention in recent years. In vitro experiments showed that Dol-10 and its derivatives were highly lethal to common tumor cells, such as L1210 leukemia cells (IC₅₀ = 0.03 nM), small cell lung cancer NCI-H69 cells (IC₅₀ = 0.059 nM), and human prostate cancer DU-145 cells (IC₅₀ = 0.5 nM), etc. With the rise of antibody-drug conjugates (ADCs), milestone progress was made in clinical research based on Dol-10. A variety of ADCs constructed by combining MMAE or MMAF (Dol-10 derivatives) with a specific antibody not only ensured the antitumor activity of the drugs themself but also improved their tumor targeting and reduced the systemic toxicity. They are currently undergoing clinical trials or have been approved for marketing, such as Adcetris^®, which had been approved for the treatment of anaplastic large T-cell systemic malignant lymphoma and Hodgkin lymphoma. Dol-10, as one of the most medically valuable natural compounds discovered up to now, has brought unprecedented hope for tumor treatment. It is particularly noteworthy that, by modifying the chemical structure of Dol-10 and combining with the application of ADCs technology, Dol-10 as a new drug candidate still has great potential for development. In this review, the biological activity and chemical work of Dol-10 in the advance of antitumor drugs in the last 35 years will be summarized, which will provide the support for pharmaceutical researchers interested in leading exploration of antitumor marine peptides.     

马尾松自由授粉家系产脂力的年度变化及遗传分析

以来自马尾松天然群体的49个高产脂优树半同胞家系子代为对象,测定6个年度产脂力.结果表明:马尾松在早期的产脂力随树龄的增长而迅速增大,13年后进入稳定期.不同家系的产脂力差异显著,但产脂力变异幅度随树龄的增长而降低.产脂力变异受中等遗传控制,其中早期遗传力较高,后期遗传力较低且稳定,家系遗传力明显高于单株遗传力.早期与成熟期的产脂力具有紧密的遗传正相关,且相关性随树龄的增长而增加.产脂力的早期选择效率随树龄的增大而提高,11年时达到0.813,是理想的早期选择时间节点.利用综合育种值法筛选到13个优良产脂家系,入选家系的年度育种值均显著高于对照,且随树龄的增大而增加.     

Comparative Study About Some Physical Properties, In vitro Digestibility and Immunoreactivity of Soybean Protein Isolate for Infant Formula

The objective of this study was to determine molecular weight subunit distributions of soy protein isolate (SPI) by SDS-PAGE and gel size exclusion chromatography, and further to investigate the differences of thixotropy, viscosity, in vitro digestibility and immunoreactivity of SPI for infant formula produced in Chinese domestic companies and world famous SPI manufacturers such as Dupont and Fuji. The molecular subunit distributions were analyzed by SDS-PAGE and gel size exclusion chromatography, indicating that Solae and Fuji were hydrolyzed by proteolytic enzymes. The thixotropy of Fuji and Solae significantly reduced around by 95 %, compared with those of Mantianxue and Dupont Zhengzhou. The allergen contents of Fuji and Solae strikingly decreased by 60 and 84 % respectively, in contrast to that of Mantianxue. The in vitro protein digestibility of Solae at the end of pepsin and trypsin digestion markedly increased by 11.7 and 11.3 %, respectively, in comparison to those of Mantianxue. Suitable enzymatic hydrolyzed SPIs showed lower thixotropy, viscosity, immunoreactivity and higher in vitro protein digestibility than those from the other SPIs. The lower thixotropy indicates low difficulty or shear stress in swallowing for infants. The lower immunoreactivity will improve the safety of SPI for cow milk allergic babies.