Contents of Volume 53

Plant Molecular Biology -     

The Stress Hormone Corticosterone Increases Synaptic ��-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid (AMPA) Receptors via Serum- and Glucocorticoid-inducible Kinase (SGK) Regulation of the GDI-Rab4 Complex

Corticosterone, the major stress hormone, plays an important role in regulating neuronal functions of the limbic system, although the cellular targets and molecular mechanisms of corticosteroid signaling are largely unknown. Here we show that a short treatment of corticosterone significantly increases α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR)-mediated synaptic transmission and AMPAR membrane trafficking in pyramidal neurons of prefrontal cortex, a key region involved in cognition and emotion. This enhancing effect of corticosterone is through a mechanism dependent on Rab4, the small GTPase-controlling receptor recycling between early endosome and plasma membrane. Guanosine nucleotide dissociation inhibitor (GDI), which regulates the cycle of Rab proteins between membrane and cytosol, forms an increased complex with Rab4 after corticosterone treatment. Corticosterone also triggers an increased GDI phosphorylation at Ser-213 by the serum- and glucocorticoid-inducible kinase (SGK). Moreover, AMPAR synaptic currents and surface expression and their regulation by corticosterone are altered by mutating Ser-213 on GDI. These results suggest that corticosterone, via SGK phosphorylation of GDI at Ser-213, increases the formation of GDI-Rab4 complex, facilitating the functional cycle of Rab4 and Rab4-mediated recycling of AMPARs to the synaptic membrane. It provides a potential mechanism underlying the role of corticosteroid stress hormone in up-regulating excitatory synaptic efficacy in cortical neurons.     

糙叶败酱挥发油镇静作用的研究

本文观察了败酱科植物糙叶败酱(Patrinia scabra Bunge)根和根茎中制得的挥发油的镇静作用,井与黄花败酱挥发油做了比较。结果表明,此油灌胃给予数组小鼠,剂量0.45ml/kg,显示如下的作用:[1]能显著延长由于腹腔注射戊巴比妥钠(50mg/kg)引起的小鼠睡眠时间,但其作用强度弱于黄花败酱挥发油。(2)一次灌胃给予小鼠大剂量10.46g/kg的糙叶败酱挥发油,连续观察10天,动物外观正常,无一死亡,体重增加与对照组相似。     

Gene-specific formation and repair of cisplatin intrastrand adducts and interstrand cross-links in Chinese hamster ovary cells

We have used three methods to study the formation and repair of intrastrand adducts and interstrand cross-links in the DNA of Chinese hamster ovary cells induced by the anticancer drug cis-diamminedichloroplatinum II (cisplatin). Using atomic absorption spectroscopy, we found that 21% of the total genomic cisplatin adducts were removed at 8 h and 42% at 24 h. We used ABC excinuclease digestion, coupled with out previously reported methodology to quantify DNA in specific genomic regions. These adducts were removed faster in the transcribed dihydrofolate reductase and c-myc genes compared to a noncoding fragment, a region containing the little or nontranscribed c-fos oncogene, and to the overall genome. Interstrand cross-links in specific sequences were quantified by Southern hybridization of denatured-renatured DNA separated on a neutral gel. We found that cross-links were removed more efficiently from the gene regions than intrastrand adducts and, at high levels of cross-linking, removal was similar from transcribed and from nontranscribed regions.     

水稻对褐飞虱抗性相关蛋白的双向电泳分析

以药用野生稻 (Oryzaofficinalis)的转育后代B5 (高抗褐飞虱 (NilaparvatalugensSt l) )与感虫品种明恢 6 3(OryzasativaL .)为亲本 ,构建了一个重组自交系群体。通过抗褐飞虱鉴定 ,筛选出极端抗虫株系和极端感虫株系 ,运用分群分析法 (bulkedsegregantanalysis ,BSA)分别建成了极端抗虫集团 (resistantbulk)和极端感虫集团 (susceptiblebulk)的蛋白质池。利用双向电泳技术 ,分别分析了极端抗虫集团和极端感虫集团受虫害与未受虫害的秧苗蛋白质的变化。结果发现 ,虫害 48h后 ,感虫集团的一个分子量为 40kD的蛋白质P40 (pI=6 .3)的表达明显减弱甚至消失 ,而在抗虫集团中 ,P40的表达未受影响。与褐飞虱为害后抗虫株系和感虫株系不同的生理反应相联系 ,推测P40与水稻受褐飞虱虫害后引起的应答反应相关     

一个新型耐热普鲁兰酶的结构与功能

新型普鲁兰酶的研究对于普鲁兰酶制剂的国产化、打破国外垄断具有非常重要的意义。从我国云南腾冲地区轮马热泉的淤泥中分离获得了一株耐热普鲁兰酶产生菌LM 18-11,经16S rDNA序列系统进化树分析,确定该菌为厌氧芽胞杆菌Anoxybacillus属种,并从中克隆获得了耐热普鲁兰酶的编码基因,该酶在55℃-60℃、pH 5.6-6.4的范围内具有最大的反应活性。此外,该酶具有较好的热稳定性,在60℃下处理48 h,仍可保持50%以上的活力;动力学分析该酶的Vmax和Km分别为750 U/mg和1.47 mg/mL,是目前文献报道中比活力最高的耐热普鲁兰酶。同时还对该酶进行了晶体结构分析,结果显示该酶具有?-淀粉酶家族中典型的结构,在N端具有一个特殊的底物结合域,该结构域的缺失导致比活力和底物结合力都有相应降低,Vmax和Km分别为324 U/mg和1.95 mg/mL。同时,将该普鲁兰酶编码基因导入枯草芽胞杆菌中,在P43启动子的控制下,普鲁兰酶基因获得了高效表达,胞外酶活可达42 U/mL,相比初始菌种,表达活力提高40倍以上。研究表明该普鲁兰酶具有很好的应用前景。     

Detection of several harmful algal species by sandwich hybridization integrated with a nuclease protection assay

The frequent occurrence of harmful algal blooms (HABs) is a pressing topic in marine research. An integrated sandwich hybridization and nuclease protection assay was established to qualitatively and quantitatively detect 12 harmful algal species. This method demonstrated good reliability, specificity and accuracy for analyzing samples from individual and mixed cultures, as well as field collection, and cell volumes were positively correlated to the slopes of calibration curves. The lowest quantitative detection limits were those concentrations observed during blooms; thus, this technique provides an efficient alternative to microscopy for rapid identification and quantitation of harmful algal species and could be routinely used to monitor phytoplankton in field surveys.     

一株抗锰土壤芽胞杆菌的分离鉴定与生物学活性分析

从山东崅屿采集的黄棕壤中分离得到一株具有抗Mn(Ⅱ)和Mn(Ⅱ)氧化双重活性的芽胞杆菌,其最高Mn(Ⅱ)耐受浓度达到130mmol/L,对Mn(Ⅱ)的氧化活性为3.3μmol/(L·d)。通过个体形态与培养特征观测、生理生化反应、G+Cmol%测定和16SrDNA序列比对分析等鉴定,确定该菌株为巨大芽胞杆菌(Bacillus megaterium),命名为MB283。该菌株在添加Mn(Ⅱ)(10mmol/L)条件下比不添加Mn(Ⅱ)表现出相对较快的生长速率。采用高温培养并结合0.01%SDS处理,从MB283菌株筛选到一株发生内生质粒消除的突变株MB287,具有与野生菌株类似的锰耐受活性,且对Mn(Ⅱ)的氧化活性与野生菌株相比无明显改变,表明野生菌株MB283中与锰抗性和锰氧化相关的基因可能是定位于该菌的染色体上。