Ecological modelling Internet resources

Internet resources are grouped into registers and sources of ecological models (6 addresses), sources of documents (7), sources of data (5), initiatives (5), societies (4), journals (4) frequently asked questions (7), extensive list of links to Web pages (4), search engines (5) and Usenet groups (10). At present, Internet resources are not replacing classical libraries but should be considered as complementary sources of information.     

瞬时表达比较马铃薯X病毒CP基因3种结构对RNA沉默的诱导效果

RNA沉默是植物抵御病毒侵染的一种防卫机制,病原来源的抗性(pathogen-derived resistance,PDR)被认为是通过RNA沉默起作用的.转化的核酸片段在基因组中的位置、长短和不同排列结构等均影响RNA沉默的效率.用全长马铃薯X病毒(PVX)CP基因构建非翻译的正义、反义和反向重复结构转基因的植物表达载体,通过农杆菌渗入法瞬时表达测试了这些转基因对RNA介导抗性的诱导效率和有效性.结果表明,反向重复的PVXCP是更为有效的RNA沉默诱导因子,同时也证明让目的基因在受试植物中瞬时表达,在转化植物之前能比较快速地检测转基因的表达情况以及表达产物的功能,从而节约时间和资源,并减少盲目性.图3表2参21     

Cyp35a2 gene expression is involved in toxicity of fenitrothion in the soil nematode Caenorhabditis elegans

In this study, the effect of organophosphorous (OP) pesticide, fenitrothion (FT), on the non-target organism was investigated using the soil nematode, Caenorhabditis elegans. Toxicity was investigated on multiple biological levels, from organism to molecular levels, such as, immoblity, growth, fertility, development, acetyl cholinesterase (AChE) activity and stress-response gene expressions. FT may provoke serious consequences on the C. elegans population, as it induced significant developmental disturbance. As expected, FT exposure inhibits AChE activity of C. elegans. The increased expression of the cytochrome p450 family protein 35A2 (cyp35a2) gene was also observed in FT exposed worms. To experimentally demonstrate the relationships between organism-level effects and the cyp35a2 gene expression in FT-exposed C. elegans, the integration of the gene expression with biochemical-, and organism level endpoints were attempted using a C. eleganscyp35a2 RNA interference (RNAi) and cyp35a2 mutant (gk317). The 24 h-EC50s of C. elegans on FT exposure were in the order of cyp35a2 RNAi in cyp35a2 mutant (gk317) > cyp35a2 mutant (gk317) > cyp35a2 RNAi in wildtype (N2) > wildtype (N2). The higher EC50 values of cyp35a2 RNAi and cyp35a2 mutant (gk317) compared to that of wildtypeC. elegans strongly supported that cyp35a2 gene plays an important role in the toxicity of FT towards C. elegans. The experiments with cyp35a2 RNAi also indicated that the development disturbance and decreased AChE activity, which were observed in FT exposed wildtype C. elegans were significantly rescued in the cyp35a2 RNAi C. elegans. Overall results suggest that the cyp35a2 may be an important gene for exerting FT toxicity in C. elegans.     

苏丹红Ⅰ、Ⅲ和Ⅳ对HepG-2细胞和SGC-7901细胞增殖的影响

以辽宁某地硼矿开采和加工厂的硼作业工人以及远离硼矿的背景地区的人群作为研究对象,分析了班后尿液硼浓度与日硼暴露剂量之间的关系.结果表明,班后尿硼浓度与日硼暴露剂量之间存在着显著的对数线性关系,考虑了不同人群类别的影响之后,回归方程的拟合度达到85.9%,由此确立了用班后尿硼浓度预测日硼暴露剂量的预测方程.用此预测方程对本研究2004年的受试者日硼暴露剂量进行预测,并与实测值进行了比较,结果表明平均相对偏差为13.4%,预测值与实测值之间没有显著性的差异.说明用班后尿硼浓度预测日硼暴露剂量是可行的.对2004年所有受试者的日硼暴露剂量预测结果分析表明,硼职业暴露组、社区对照组和背景对照组的日硼暴露剂量平均值分别为36.1、4.13和1.31mg/d.     

In vitro effect of profenofos,fenvalerate and dimilin on protein and RNA biosynthesis by rabbit liver and muscle tissues

Abstract

The present study was carried out to investigate the effect of Curacron (profenofos), Sumicidin (fenvalerate) and Dimilin (di‐fluobenzuron) on the in vitro rate of protein and RNA synthesis by rabbit liver and muscle tissues. The synthesis of protein and RNA were significantly stimulated in the liver and inhibited in the muscle by graded doses of these insecticides. Profenofos showed maximum effect on protein synthesis in both tissues at a dose of 0.2 μg/mL, while the maximum effect on RNA synthesis occurred at 0.2 μg/mL in the liver and at 2 μg/mL in the muscle. Fenvalerate caused maximum stimulation in both liver protein and RNA synthesis at a dose of 2 μg/mL, and maximum inhibition in the muscle at 10 and 0.2 μg/mL for protein and RNA synthesis respectively. The maximum effect of Dimilin on both tissues was reached at 5 μg/mL for protein synthesis and at 0.2 μg/mL for RNA synthesis. The effect of Dimilin on RNA synthesis was more pronounced in both tissues than its effect on protein synthesis, but this trend was reversed in the case of profenofos and fenvalerate. Present data also showed antagonism between these insecticides on the rate of protein and RNA synthesis.     

Responses of juvenile sea bass, Dicentrarchus labrax, exposed to acute concentrations of crude oil, as assessed by molecular and physiological biomarkers

In the present study, juvenile sea bass were exposed for 48 and 96 h to an Arabian light crude oil and their responses were assessed at the molecular and physiological levels. The aim of the study was therefore to assess (i) the short term effects of crude oil exposure by the measurement of several molecular biomarkers, (ii) the consequences of this short term exposure on fish health by using growth and condition indices measured after a decontamination period of 28 and 26 d in seawater. Hydrocarbon petroleum concentrations was monitored during the 96 h experiments and an increase of PAH concentrations were found in fish following both exposure times. An 7-ethoxyresorufin-O-deethylase (EROD) induction was observed after 48 h of exposure, while a significant decrease in the sea bass specific growth rate in length and for the RNA:DNA ratio was observed 28 d after that exposure ceased. The EROD induction doubled after the 96 h exposure, and a significant increase in GST activities was observed. A significant decrease in the specific growth rates, the otolith recent growth, the RNA:DNA ratio and the Fulton’s K condition index were then observed in sea bass 26 d after the 96 h exposure to mechanically dispersed crude oil compared to the control. The present study shows that growth and condition indices can prove useful in assessing fish health status following an oil spill. Their complementary analysis with sensitive molecular biomarkers as EROD could improve the determination of oil spill impact on fish populations.     

A numerical model for transient-hysteretic flow and solute transport in unsaturated porous media

A two-dimensional flow and transport model was developed for simulating transient water flow and nonreactive solute transport in heterogeneous, unsaturated porous media containing air and water. The model is composed of a unique combination of robust and accurate numerical algorithms for solving the Richards', Darcy flux, and advection-dispersion equations. The mixed form of Richards' equation is solved using a finite-element formulation and a modified Picard iteration scheme. Mass lumping is employed to improve solution convergence and stability behavior. The flow algorithm accounts for hysteresis in the pressure head-water content relationship. Darcy fluxes are approximated with a Galerkin and Petrov-Galerkin finite-element method developed for random heterogeneous porous media. The transport equation is solved using an Eulerian-Lagrangian method. A multi-step, fourth-order Runge-Kutta, reverse particle tracking technique and a quadratic-linear interpolation scheme are shown to be superior for determining the advective concentration. A Galerkin finite-element method is used for approximating the dispersive flux. The unsaturated flow and transport model was applied to a variety of rigorous problems and was found to produce accurate, mass-conserving solutions when compared to analytical solutions and published numerical results.     

F-RNA噬菌体及其作为水中肠道病毒指示物的研究进展

城市污水的再生利用是缓解水资源紧张、减少水污染和改善生态环境的有效途径。污水及其回用水中的肠道病毒对人体健康的风险日益受到关注。直接检测水中肠道病毒的操作复杂、安全性差、时间长、需要专门的技术和设备，因此需要寻找合适的指示生物，以实现对水中肠道病毒的及时检测和风险评价。F-RNA噬菌体是通过性菌毛感染雄性大肠杆菌的一类RNA细菌病毒，在污水中普遍存在，在大小、形态结构及对环境条件和水处理过程的抗性与肠道病毒相似，被认为是水中肠道病毒的合适的指示生物。文章介绍了F-RNA噬菌体在环境及污水中的分布、存活和去除特性、检测方法及作为水中肠道病毒指示生物的研究进展。     

植物生物技术在黑麦草遗传改良中的应用

黑麦草是重要的牧草和草坪草,是畜牧业和草坪业重要的产业支柱.由于高度自交不亲和,传统遗传改良困难而复杂.生物技术尤其是转基因技术为其遗传改良带来希望.本文概述了组织培养技术、基因遗传转化技术、分子标记及数量性状基因定位、分子标记辅助育种等技术在黑麦草遗传改良中的应用及获得的成果;评述了遗传改良的重要意义,以及黑麦草遗传改良的主要目标,如品质改良、提高病害抗性、降低毒性生物碱浓度、控制花粉致敏性、抗除草剂品种的培育、提高抗逆性及其作为生物反应器的潜在应用价值等;并分析了功能基因组学的研究及RNA干扰技术在黑麦草研究中可能的应用前景.