灭多威的污染现状及其对水生生物的毒性效应研究进展

灭多威属氨基甲酸酯类农药,可用作杀虫剂、杀菌剂及除草剂,具选择性强、高效、易分解降解等特性,被广泛应用于农林业的生产.为了探究灭多威的污染现状、污染严重程度,笔者综述了灭多威研究现状,并系统汇总了国内外对灭多威毒性效应研究实例,重点综述了灭多威的应用与污染现状、对水生生物生殖毒性效应、组织器官及DNA的损伤等,并在此基...     

转基因产品中抗除草剂基因的PCR检测

抗除草剂作物占全球转基因作物的75％以上，并且这类作物还有不断增加的趋势。首次建立并优化了对4类转基因作物（大豆（Glycine max）、玉米（Zea mays）、棉花（Gossypium hirsutnm）和油菜（Brassica campestris var.oleifera））的5种外源抗除草剂基因（bar、pat、cp4-epspsI、cp4-epsps2和gox）的PCR检测方法，并在实践中应用。结果表明，本方法灵敏特异、结果准确可靠，可对目前批准的所有抗除草剂转基因产品进行定性检测。     

基于局部均值分解的触电故障信号瞬时参数提取

针对如何快速、准确地提取生物体触电故障暂态信号中的电力参数问题,提出了一种基于局部均值分解（local mean decomposition, LMD）的生物体触电时总泄漏电流信号瞬时参数提取方法,该方法首先利用局部均值分解将生物体触电时的总泄漏电流信号分解为一组乘积函数分量之和,每个乘积函数（product function, PF）分量可以表示为一个调幅信号和一个调频信号的乘积,然后由调幅信号和调频信号分别计算得到信号的瞬时幅值和瞬时频率。与采用希尔伯特黄变换方法相比,LMD具有瞬时频率曲线波动小和瞬时幅值函数端部失真小等优点。仿真信号分析结果表明：对测试信号进行LMD和经验模态分解（empirical mode decomposition, EMD）分解分别得到3个PF分量和5个IMF（intrinsic mode function）分量,分解前后信号的能量变化值分别为0.2851、0.5633,且LMD比EMD所需分解时间短0.0743s,与Hilbert变换相比,该文方法计算的瞬时幅值和瞬时频率更为平滑,在一定程度上避免了Hilbert 变换计算过程中的负频率和端点效应现象。试验信号分析结果表明：对消噪后的总泄漏电流信号进行LMD和EMD分解,分别得到5和6个分量,分解前后信号的能量变化值各为0.5574、0.8896,所用分解时间分别为0.0835、0.2479 s;在求取瞬时频率方面,LMD方法求取的主导分量瞬时频率可判定生物体触电时刻,而经Hilbert变换求取的瞬时频率不仅无法判定生物体触电时刻,还出现了负的频率值,无法解释其物理意义;在求取瞬时幅值方面,该文方法与Hilbert变换求取的触电前总泄漏电流信号的瞬时幅值的平均值分别为11.3240、12.3728 mA,与原生物体无触电时总泄漏电流的幅值11.3538 mA的绝对误差分别为0.0298、1.0190 mA,另外,2种方法求取的生物体触电后总泄漏电流信号的瞬时幅值与原生物体触电后总泄漏电流的幅值的绝对误差分别为0.4340、0.6643 mA。因此,仿真信号和试验信号分析结果均证明所提方法是有效和可行的。     

Five-year trends in soil arthropod densities in pine forests with various levels of vitality

Summary A comparative field study was conducted to study the correlation between forest vitality and the abundance of soil microarthropods. During 5 years the vitality of six pine forests within the Veluwe area, the Netherlands, was estimated by the number of needle year-classes, while soils were sampled and extracted for various soil microarthropod groups. Within sites the number of needle year-classes in the forest stands fluctuated over the 5 years, while the collembolan family Sminthuridae showed a trend towards a decreasing population density and the density of the cryptostigmatid mite Platynothrus peltifer Koch increased. Among sites there was a significant positive correlation between the number of needle year-classes and the relative abundance of P. peltifer. The results imply that soil microarthropods may indicate changes in physical and chemical factors in relation to soil fertility and vitality of the trees.     

土壤动物在土壤有机质形成中的作用

作为土壤生态系统重要组成部分的土壤动物,在土壤元素循环转化和迁移过程中发挥着重要的作用。土壤动物是凋落物分解的"微型粉碎机",通过体内"特殊转换器",影响土壤有机质的转化、腐殖质的形成。本文从土壤动物对地表枯落物分解入手,分析了影响土壤动物对凋落物分解的因素,土壤动物通过刺激土壤酶活性,与土壤微生物群落一起,加快土壤有机物的分解,促进土壤腐殖质的转化。旨在拓宽土壤动物生态功能,丰富土壤腐殖质形成机理学说,对保护土壤生物多样性、提高土壤地力、保障粮食安全具有重要的科学意义。     

The contribution of endogenous cellulase to the cellulose digestion in the gut of earthworm (Pheretima hilgendorfi: Megascolecidae)

Cellulase activity has been detected in the digestive tract of earthworms. However, it has not been well clarified whether the origin of those cellulases are the earthworm themselves or the symbionts. In our study, zymogram analysis suggests that one cellulase (endo-β-1,4-glucanase, EC3.2.1.4) mainly works to digest cellulose in Pheretima hilgendorfi. To identify the cellulase in P. hilgendorfi, we carried out cDNA cloning of the cellulase gene from the digestive tract. A novel cellulase gene was identified from the gut of earthworm. The cDNA encoding cellulase of P. hilgendorfi (phhEG) is 1606 bp with an open reading frame encoding a protein of 449 amino acid residues. The deduced amino acid sequence of P. hilgendorfi cellulase showed higher homology to invertebrate cellulases than bacterium cellulases belonging to the glycosyl hydrolase family (GHF) 9. The phhEG gene was detected in intestinal epithelium cell of midforegut using Northern blot and in situ hybridization. Similarly, specific cellulase activity against carboxymethyl cellulose (CMC) was significantly higher in midforegut tissue. Recombinant phhEG produced by wheat germ cell-free protein synthesis system had a cellulase activity which degrade CMC. In zymogram analysis, the molecular size of cellulase was detected as a single band of 51 kDa from the whole gut contents extracts of P. hilgendorfi, and was very similar to the predicted molecular size of the mature phhEG protein. These results strongly suggested that the earthworm has the capacity to produce the endogenous and functional cellulase around the midforegut, and use this cellulase for their cellulose digestion with the support of intestinal caecum.     

Conservation of Aquatic Biodiversity in China

本文探讨了中国目前水生生物多样性的状况。人类活动已对水生物的生存环境造成严重影响 ,面对生物多样性的丧失 ,我们应设法保护它。本文在保护水生生物多样性方面提出了一个新的观点 ,从保护流域生态环境入手以保护水生生物多样性     

转基因食品PCR定性检测的研究进展

以靶序列的选择、DNA提取和产物的检测为主线,概括了PCR(PolymeraseChainReaction,PCR)在定性检测基因修饰有机体(Geneticallymodifiedorganisms,GMOs)中的应用,指出了存在的问题以及未来的发展方向。     

水生光合生物无机碳的运输

本文综述了水生光合生物无机碳的运输。作为光合作用的无机碳源ＣＯ２和ＨＣＯ３－是水生光合生物最好的运输形式。但是，不同类型的水生光合生物无机碳的运输形式及其运输机理各不相同。