除草剂污染堆肥用量对番茄生长的影响

为降低有机肥料使用过程中痕量除草剂对农业安全生产的风险,采用市售基质、普通堆肥和受除草剂污染的堆肥为试材,设置4个处理(无污染堆肥、二氯吡啶酸污染堆肥、氟乐灵污染堆肥和环丙嘧啶酸污染堆肥),在0、5%、10%和20%不同堆肥用量条件下,以番茄的出苗率和播种后45d时植株的株高、叶片面积、茎粗、植株干质量、根长和壮苗指数为评价指标判断除草剂污染堆肥对番茄种子萌发及植株生长的影响。结果表明,除草剂污染堆肥对番茄种子的萌发及生长都有一定的抑制作用,随污染堆肥用量的增加抑制作用增加,且对作物产物抑制作用的污染堆肥用量及抑制作用大小因除草剂种类而异,二氯吡啶酸污染堆肥对番茄生长的影响最大。植物生长指标茎粗、植物干质量和根长较株高和叶面积而言,对除草剂污染更敏感。     

Predicting Crawfish Molting with Machine Vision

The objective of this project was to develop a vision system that could predict when crawfish will molt. Different sections of the crawfish shell were examined to determine how the color changed as the time of molting approached. A strip on the tail section of the crawfish showed the greatest, most consistent color change. The average red/green × red/blue ratio decreased for every crawfish as the molting time approached. Using this ratio as a predictor, it was possible to predict the molting of a crawfish within 3 d with an accuracy greater than 80%. The limitation on accuracy was primarily the result of the large variations in natural shell color among the crawfish.     

The genetic basis of insecticide resistance in the house fly: Evidence that a single locus plays a major role in metabolic resistance to insecticides

Genetic evidence indicates that insecticide resistance in insects is controlled by relatively few genes. In the house fly, Musca domestica L., major resistance genes include one for decreased uptake of insecticides, three for changes at the target sites of insecticide action, and a single gene for metabolic resistance to multiple types of insecticides. The latter gene, which is located on chromosome II, interacts with minor genes located on other chromosomes. The product of the major gene for metabolic resistance appears to be a receptor protein which recognizes and binds xenobiotics, including insecticides and plant defense substances, and then induces synthesis of appropriate detoxifying enzymes.     

Amebae and ciliated protozoa as causal agents of waterborne zoonotic disease

The roles free-living amebae and the parasitic protozoa Entamoeba histolytica and Balantidium coli play as agents of waterborne zoonotic diseases are examined. The free-living soil and water amebae Naegleria fowleri, Acanthamoeba spp., and Balamuthia mandrillaris are recognized etiologic agents of mostly fatal amebic encephalitides in humans and other animals, with immunocompromised and immunocompetent hosts among the victims. Acanthamoeba spp. are also agents of amebic keratitis. Infection is through the respiratory tract, breaks in the skin, or by uptake of water into the nostrils, with spread to the central nervous system. E. histolytica and B. coli are parasitic protozoa that cause amebic dysentery and balantidiasis, respectively. Both intestinal infections are spread via a fecal-oral route, with cysts as the infective stage. Although the amebic encephalitides can be acquired by contact with water, they are not, strictly speaking, waterborne diseases and are not transmitted to humans from animals. Non-human primates and swine are reservoirs for E. histolytica and B. coli, and the diseases they cause are acquired from cysts, usually in sewage-contaminated water. Amebic dysentery and balantidiasis are examples of zoonotic waterborne infections, though human-to-human transmission can occur. The epidemiology of the diseases is examined, as are diagnostic procedures, anti-microbial interventions, and the influence of globalization, climate change, and technological advances on their spread.     

虹鳟鱼未受精卵在人工配液中的保存方法

虹鳟鱼未受精卵保存在体腔液和以２０ｍＭＨｅｐｅｓ或Ｔｒｉｓ－ＨＣＬ作缓冲液ＰＨ为８．５的Ｃｏｒｔｌａｎｄ人工配液中。经２４小时和４８小时保存后卵子与４￣６尾雄鱼的精液进行人工授精。其中的精液用稀释液（Ｃ１２７ｍＭ Ｎａｃｌ,２０ｍＭ Ｔｒｉｓ－ＨＣＬ,ＰＨ９．５）进行稀释。记录发育到眼点期的胚胎数和孵化的胚胎数作为受精指标。与对照线相比,在１２￣１３℃保存了４８小时的虹鳟鱼卵具有同样的受精能力。实     

Real-Time Fluorescent Polymerase Chain Reaction Detection of Phytophthora ramorum and Phytophthora pseudosyringae Using Mitochondrial Gene Regions

ABSTRACT A real-time fluorescent polymerase chain reaction (PCR) detection method for the sudden oak death pathogen Phytophthora ramorum was developed based on mitochondrial DNA sequence with an ABI Prism 7700 (TaqMan) Sequence Detection System. Primers and probes were also developed for detecting P. pseudosyringae, a newly described species that causes symptoms similar to P. ramorum on certain hosts. The species-specific primer-probe systems were combined in a multiplex assay with a plant primer-probe system to allow plant DNA present in extracted samples to serve as a positive control in each reaction. The lower limit of detection of P. ramorum DNA was 1 fg of genomic DNA, lower than for many other described PCR procedures for detecting Phytophthora species. The assay was also used in a three-way multiplex format to simultaneously detect P. ramorum, P. pseudosyringae, and plant DNA in a single tube. P. ramorum was detected down to a 10(-5) dilution of extracted tissue of artificially infected rhododendron 'Cunningham's White', and the amount of pathogen DNA present in the infected tissue was estimated using a standard curve. The multiplex assay was also used to detect P. ramorum in infected California field samples from several hosts determined to contain the pathogen by other methods. The real-time PCR assay we describe is highly sensitive and specific, and has several advantages over conventional PCR assays used for P. ramorum detection to confirm positive P. ramorum finds in nurseries and elsewhere.     

The influence of thermal-hydro-mechanical processing on chemical characterization of Tsuga heterophylla

Viscoelastic thermal compression (VTC) is a type of thermal-hydro-mechanical (THM) processing that requires only a short processing time. THM processing causes some chemical transformations, the nature and extent of hydro-thermolysis depends on the special treatment conditions and the chemical nature of wood species. In the present study, the chemical transformations of the cell wall components and wood extractives during VTC treatment were investigated, and correlation between chemical characterizations and observed property changes was analyzed. For this purpose, the content of extractives and pH values were determined, and FTIR analysis was performed on extractable substances, extract-free wood, holocellulose, α-cellulose and lignin. Two temperatures and two steam exposure times were adopted to determine the influence of processing conditions on chemical characterization of Tsuga heterophylla. The results revealed that THM treatment caused a series of chemical reactions in extractives. Treatment temperature and conditioning time have significant influence on chemical changes of extractives. For all of the VTC treatments used in this study, no significant changes occurred in the lignin and α-cellulose components. The only significant chemical changes occurred in the hemicelluloses, which were primarily reduction of carbonyl and acetyl functional groups. This study also confirmed that the chemical transformation of wood correlates with property changes of VTC wood.     

Electrical or photocontrol of the rotary motion of a metallacarborane

Rotary motion around a molecular axis has been controlled by simple electron transfer processes and by photoexcitation. The basis of the motion is intramolecular rotation of a carborane cage ligand (7,8-dicarbollide) around a nickel axle. The Ni(III) metallacarborane structure is a transoid sandwich with two pairs of carbon vertices reflected through a center of symmetry, but that of the Ni(IV) species is cisoid. The interconversion of the two provides the basis for controlled, rotational, oscillatory motion. The energies of the Ni(III) and Ni(IV) species are calculated as a function of the rotation angle.     

Spin crossover in ferropericlase at high pressure: a seismologically transparent transition?

Seismic discontinuities in Earth typically arise from structural, chemical, or temperature variations with increasing depth. The pressure-induced iron spin state transition in the lower mantle may influence seismic wave velocities by changing the elasticity of iron-bearing minerals, but no seismological evidence of an anomaly exists. Inelastic x-ray scattering measurements on (Mg(0.83)Fe(0.17))O-ferropericlase at pressures across the spin transition show effects limited to the only shear moduli of the elastic tensor. This explains the absence of deviation in the aggregate seismic velocities and, thus, the lack of a one-dimensional seismic signature of the spin crossover. The spin state transition does, however, influence shear anisotropy of ferropericlase and should contribute to the seismic shear wave anisotropy of the lower mantle.