Distribution and Significance of Nitric Oxide Synthase in Brain Tissues of Rats Exposed to Deltamethrin Insecticide

The distribution of nitric oxide synthase(NOS)in brain tissues of rats exposed to deltamethrininsecticide has been examined by histochemical NADPH-diaphorase staining techniques on frozen sec-tions.After injection of deltamethrin(12.5mg/kg,i.p.),a reproducible sequence of toxic signs ofhyperexcitability were elicited.The observation and image analysis showed that,within brain sec-tions of rats exposed to deltamethrin,the numbers and the total staining areas of the NOS positiveneurons were greatly increased,especially in cerebral cortex,hippocampal formation and paraventric-ular nucleus.In addition,the density of single neuron and the processes were also increased.The re-sults suggested that deltamethrin may induce the NOS expression or activate the NOS activity.TheNOS activation may involve in the chains responsible for the excitatory neurotoxicities induced bydeltamethrin.     

Crystal structure determination of a neutral neurotoxin BmK M4 from Buthus martensii Karsch at 0.20 nm

BmK M4 is a neutral neurotoxin in the BmK toxin series.It is medially toxic and belongs to group III α-toxins.The purified sample was crystallized in rhombic space group P61.Using an X-ray diffraction technique,the crystal structure of BmK M4 was revealed by molecular replacement at 0.20 nm resolution.The model was refined.The final crystallographic R factor was 0.142 and the free R factor was 0.173.The root mean square deviation is 0.001 5 nm for the bond length and 1.753°for the bond angles.64 water molecules were added to the asymmetric unit.The refined structure showed an unusual non-prolyl cis peptide bond at residue 10.The structure was compared with group II α-toxin BmK M8 (an acidic,weak toxin).The potential structural implications of the cis peptide bond were discussed.     

Production of ethylene by gravistimulation: a potential problem with the interpretation of data from some experimental techniques

Abstract. Gravistimulation was investigated as a potential and unwanted component in the interpretation of physiological investigations on plants. Using both seedlings and mature sunflower plants, two situations are described where gravistimulation contributes significantly to the outcome of an experiment not initially designed to include this parameter. The number of adventitious roots formed in derooted seedings decreased when the tops of the plants were allowed to bend over under their own weight, and the effect correlated positively with the rate of ethylene production by non-vertical stems. In droughted mature plants, and increase in leaf and stem ethylene caused by water stress was supplemented by additional ethylene produced in the lower halves of stems. Drought had caused these stem tissues to wilt, become gravistimulated, and thus produce more ethylene. Other situations in which gravistimulated ethylene production and its physiological consequences are likely to be complicating factors in experiments are discussed. It is concluded that procedures that unnecessarily place experimental material in non-vertical orientations should be avoided.     

0.21nm分辨率BO-(L-精氨酸)牛胰岛素晶体结构研究

应用差值Fourier技术,立体化学最小二乘技术和XPLOR程序并辅以电子密度图的人工拟合,以三方二锌猪胰岛素模型为起点,解析了0.21nm分辨率BO-(L-精氨酸)牛胰岛素的晶体结构,最终R因子为18.2%,与标准键长与键角的均方根偏差分别为0.0022nm和 4.3°.从电子密度图与模型的拟合来看,独立区两个分子中B链N端加长的L-精氨酸清晰可见.相对于三方二锌猪胰岛素分子,B链N端晶体学微环境发生了变化.     

通过染色体外同源重组建立乳腺中表达外源基因的转基因小鼠

为研究染色体外重组方法在创建转基因动物中的应用,选取牛asl酪蛋白基因的5′及3′侧翼区和氯霉素乙酰化酶编码区,构建了两个具有3 kb相互重叠的融合基因.将这两个DNA片段末端脱磷酸后,以摩尔比1:1的比例混合,通过显微注射导入小鼠受精原核,最后获得了11个品系的转基因小鼠.对其中10个品系的小鼠的整合分析表明,所注射的两个DNA片段均发生了染色体外同源重组,而且除了 1个品系的小鼠丢失了大约1kb的序列外,其余品系小鼠的重组产物与预想的结构符合.在当代和后代的转基因小鼠乳汁中均可测到氯霉素乙酰化酶的活性.这表明融合基因在转基因小鼠乳腺中得到表达和分泌,也说明显微共注射两个相互重叠的基因片段是建立转基因动物的一个可行途径.     

温度变化对化州市水稻两迁害虫发生的影响

利用广东省化州市1959—2008年气温资料及化州市病虫测报站1989—2008年稻飞虱、稻纵卷叶螟Cnaphalocrocis medinalis(Guenée)田间测报资料,运用统计分析方法分析了该地区气温变化与稻飞虱、稻纵卷叶螟发生的关系。结果表明:与1959—1988年1—4月各旬平均气温比较,1989—1998年气温变化不明显,而从1999—2008年呈明显的增温态势,这种气候背景使得上述2害虫发生期和发生程度随1—4月平均气温的升高而显著提前和加重,平均气温与发生期和发生程度的相关性达到显著或极显著水平。     

灰岩粗毛藤(大戟科)——广东省一新记录种

报道在深圳市龙岗区排牙山求水岭发现的1个广东省新记录种--大戟科粗毛藤属灰岩粗毛藤Cnesmone tonkinensis (Gagnep.) Croiz.,并对该种的形态、生境、所在群落的特征等进行描述。该标本的采集地排牙山是其分布的最东界。     

北沙参中佛手柑内酯的分离鉴定及体外抗肿瘤活性的初步测定

北沙参为传统的中药材,来源于伞形科(Umbelliferae)植物珊瑚菜(Glehnia littoralis Fr. Schmidt ex Miq. )的干燥根,具有养阴清肺、益胃生津的功效[1],其道地产地为山东莱阳.     

食用调和油中花生油含量的近红外光谱分析

采用偏最小二乘法(PLS)等方法建立了食用调和油中花生油含量定量分析的近红外光谱定标模型。采集食用调和油样品在4 000 cm-1~10 000 cm-1范围内的近红外漫反射光谱,光谱经一阶导数处理后,采用偏最小二乘法建立样品中花生油含量的定标模型,并用Leave-one-out内部交叉验证法对模型进行验证。模型相关系数为0.99961,校正均方根RMSEC为0.830%。比较不同光谱预处理方法对定标模型的影响,结果表明一阶导数Corr.coeff最好。采用不同的化学计量学方法建立的定标模型中以偏最小二乘回归法最理想。