维管植物木质部输导特性以及仿生应用的研究

本文从细胞壁、导管(管胞)、木质部三个不同的层次分别论述了维管植物木质部的耐压性和韧性机理,并对木质部强有力的输导性机理进行了阐述。从仿生学角度出发,分别提出了仿生耐压管道和一次性超强榆导毛细管束的仿生结构模型。其中仿生耐压管道自内向外分别由内管、纤维层、增厚层、均压层和保护层组成,具有很好的耐压性和一定的保温性;一次性超强输导毛细管束采用许多根微细的毛细管加以穿孔板组成,能最大限度地维持水的内聚张力。     

生物芯片技术及其应用

生物芯片是指包被在固相载体上的高密度ＤＮＡ、抗原、抗体、细胞或组织的微点阵,它是微电子学和分子生物学结合产生的新技术。该技术被评为１９９８年度世界十大科技进展之一。本文讨论了生物芯片技术的发展、技术参数、相关仪器的发展和在ＤＮＡ序列测定、基因表达分析、基因分型、基因多态性分析、疾病的诊断、突变分析、药物筛选和微生物的鉴定等方面的应用。     

抗菌肽及其工业应用前景

抗菌肽是生物体内经诱导产生的一种对抗外源性致病菌作用的防御性小分子多肽,广泛存在于动植物和微生物体内。其分子量一般在4000Da左右,带正电荷,由30～40个氨基酸组成。抗菌肽一般都具有耐热性,100℃温度下活性最长可保持30min以上。抗菌肽具广谱抗菌活性,通过破坏细胞膜等作用,可以抑制革兰氏阴性菌、革兰氏阳性菌、真菌,有些抗菌肽还具有抗原虫、病毒及抗癌功能。抗菌肽在工业应用中展示出了广阔的前景。     

Comparison of methods for deploying female gypsy moths to evaluate mating disruption treatments

1 Mating disruption is the primary tactic used to reduce rates of gypsy moth population spread in the United States Department of Agriculture’s Slow‐the‐Spread of the gypsy moth programme (STS). Because STS targets very low‐density gypsy moth populations within which it is extremely difficult to collect females or egg masses, mating success in native populations cannot be determined. Therefore, the evaluation of mating disruption treatments in field experiments such as those designed to test new formulations and application methods requires deploying and recovering laboratory‐reared female moths to determine mating success. 2 Five methods of deploying females were evaluated for cost, rates of female and egg mass recovery, and female mating success. The deployment methods tested were: modified delta trap, square barrier, single and double trunk bands, and tethered females. 3 Deployment of tethered females had the highest cost and mating success rate, but it did not yield the highest rates of female and egg mass recovery. Deployment of females in delta traps produced the lowest cost and mating success rate, but yielded the highest recovery rate. Neither of these deployment methods is recommended because of unacceptably high cost (tethered female) or low mating success (delta trap). 4 There were no significant differences in cost or mating success among the other three deployment methods. 5 The differences among the square barrier, single trunk band, and double trunk band methods in cost, female and egg mass recovery, and mating success are too small to recommend any one over the others.     

Effect of volume and concentration of conidial suspensions of Coniothyrium minitans on infection of Sclerotinia sclerotiorum sclerotia

White mould, caused by Sclerotinia sclerotiorum, is a serious disease affecting a wide range of agricultural and horticultural crops. Biological control is one option available to limit its damage. Field experiments to evaluate various concentrations and volumes of Coniothyrium minitans spore suspensions applied to S. sclerotiorum-infected bean crops were conducted in 1997 and 1998. Percentage sclerotia infected by C. minitans were scored. Three replicate experiments were performed in time in 1997 with 21 combinations of isolates, volumes and concentrations, including two controls. In 1998, 22 combinations of isolates, volumes and concentrations plus two controls were used, combined with the absence or presence of a maize buffer, with two replicates for each. Isolates as well as concentration and volume had no effect on infection by C. minitans, but there was a significant effect of total dose (volume×concentration) of inoculum applied over the full range from 100 L ha^-1 at 10⁴ conidia mL^-1 to 1000 L ha^-1 at 10⁷ conidia mL^-1. Percentage infected sclerotia increased linearly with log (dose) as well as from 1 to 4 weeks after application of C. minitans, and reached a level of about 100% at high doses under the humid conditions of 1998. Apothecia of S. sclerotiorum developing from sclerotia in collected soil samples from the 1997 experiment showed no significant effect of C. minitans inoculum dose, but there was a significant effect of the replicate experiments. The influence of weather conditions is highlighted, and the implications of the results for cost-effective biocontrol of S. sclerotiorum are discussed.     

Fluoride Ingestion After Brushing with a Gel Containing a High Concentration of Fluoride

The aim of the study was to evaluate the amount of fluoride remaining in the oral cavity of children after brushing with fluoride gel (1.25% F). The study involved six groups of 7-year-old and six groups of 11-year-old children. The procedure was carried out according to the manufacturer’s recommendations. Fluoride concentrations were determined using ion-selective fluoride electrode. No statistically significant difference was found between the amount of fluorides that remained in the oral cavity of younger and older age group (1.2 and 1.3 mg, respectively; p > 0.05). The amount of fluorides swallowed during the procedure in both age groups proves to be within acceptable limit, as far as risk of acute poisoning symptoms is concerned. The individual daily fluoride exposure during the day of procedure seems to be twice as high compared to average fluoride intake from diet and dentifrice, and it does not exceed Tolerable Upper Intake Level for children more than 8. In younger children, it seems justifiable to reduce the amount of the preparation applied on a toothbrush, especially when daily use of the gel is recommended.     

根域限制和氮素水平对连翘幼苗生长的影响

在植物生长箱通过溶液培养试验,从叶片光合气体交换参数、叶绿素含量及其荧光参数等方面来探讨不同氮素浓度条件下根域体积对连翘幼苗光合生理特性及生长的影响,并采用^15N示踪技术对不同氮素浓度条件下根域体积对连翘幼苗体内氮素转运进行了研究。结果表明：低氮（LN）处理幼苗的地上部和根系干物质重较高氮（HN）处理的高,根域限制对地上部和根系干物质重的影响不同,LN处理幼苗地上部和根系干物质重在低根域体积（10cm×10cm×15cm,LR）处理均较高根域体积（20cm×10cm×15cm,HR）处理的低,HN处理的幼苗响应情况有所不同。LN处理幼苗的叶片净光合速率（Pn）和叶绿素含量较HN处理的高;LN处理幼苗Pn和气孔导度（Gs）在LR处理较HR处理的高,而HN处理幼苗的Pn和Gs随根域体积变化规律与LN处理相反,LN和HN处理叶绿素含量随根域体积变化规律与Pn相反。LN处理幼苗的PSⅡ最大光化学量子效率（Fv／Fm）和PSⅡ电子传递量子效率（ФPSⅡ）均较HN处理的高,不同供氮处理下LR处理幼苗的Fv／Fm均较HR处理的高;而ФPSⅡ的变化规律相反。不同供氮处理时,LR处理幼苗的光化学猝灭系数（qP）均较HR处理的低,而非光化学猝灭系数（qNP）的变化规律相反,LN处理幼苗的qNP较HN处理的高（P〈0．05）。不同供氮处理时,LR处理幼苗根系和地上部氮含量均较HR处理的低,LN处理幼苗根系和地上部氮含量较HN处理的低,幼苗根系和地上部氮含量随氮素浓度变化差异显著（P〈0．05）。LN处理幼苗根系吸收^15N在根系和叶片的分配率均较HN处理的低,而根系吸收^15N在枝和茎的分配率呈相反变化规律。根系吸收氮在叶片和枝的分配率分别为7％～10％和7％～12％,叶片和枝生长需要的氮素主要由其内源N库提供。     

新抗生素莫西沙星国内外研究应用最新进展

莫西沙星(moxifloxacin)属第四代氟喹诺酮类抗菌药物。莫西沙星通过抑制细菌的DNA螺旋酶A亚单位和拓扑异构酶IV的活性,阻断DNA的复制,从而发挥杀菌作用。对革兰阴性菌、阳性菌均有强大的抗菌能力,对支原体、衣原体、军团菌有效,对厌氧菌感染有效,尤其对某些临床常见的耐药菌有效。临床应用莫西沙星治疗社区获得性肺炎、急性细菌性鼻窦炎、泌尿生殖系感染、继发性腹膜炎、肺结核的早期及延长早期间治疗、强直性脊椎炎和皮肤、皮下组织感染的治疗。     

联合应用siRNA和拉米夫定抑制HBV复制和表达的实验研究

观察联合应用小干扰RNA和拉米夫定对HepG2.2.15细胞中HBV抗原表达和复制的抑制作用。构建并转染重组质粒psil-HBV到HepG2.2.15细胞中。转染后的细胞培养基中加入拉米夫定(0.05μm),分别于48、72、96 h收获细胞。用ELISA方法检测HBeAg和HBsAg;HBV DNA水平用实时定量PCR测定;用逆转录PCR检测HBV mRNA水平。96 h后联合应用小干扰RNA和拉米夫定组细胞培养上清中HBeAg和HBsAg抑制率分别为91.8%和82.4%(P<0.05);HBV mRNA表达水平明显降低。HepG2.2.15细胞中联合应用小干扰RNA和拉米夫定对HBV复制的抑制作用比单独应用siRNA或拉米夫定更有效。     

对(艹孟)烷-3,8-二醇的合成与应用研究进展

对(艹孟)烷-3,8-二醇是一种具有生物活性的化合物,主要来源于柠檬桉精油,可直接用于香水、杀虫剂和药品等.通常采用化学和生物化学的方法合成对(艹孟)烷-3,8-二醇,以替代从柠檬桉叶油分离得到的天然产品.以香茅醛为原料通过Prins环缩合和水解,或者通过Solanum aviculare悬浮培养方式进行生物转化得到对(艹孟)烷-3,8-二醇;通过薄荷醇的氧化,或者以2-丁烯醛为原料与甲基锂、NaClO2等试剂经过较长步骤也可合成对(艹孟)烷-3,8-二醇.对(艹孟)烷-3,8-二醇可应用于制造驱虫剂、凉味剂、药物或者化妆品的添加剂以及海水防护涂料添加剂等.