Sequence-selective recognition of DNA by strand displacement with a thymine-substituted polyamide

A polyamide nucleic acid (PNA) was designed by detaching the deoxyribose phosphate backbone of DNA in a computer model and replacing it with an achiral polyamide backbone. On the basis of this model, oligomers consisting of thymine-linked aminoethylglycyl units were prepared. These oligomers recognize their complementary target in double-stranded DNA by strand displacement. The displacement is made possible by the extraordinarily high stability of the PNA-DNA hybrids. The results show that the backbone of DNA can be replaced by a polyamide, with the resulting oligomer retaining base-specific hybridization.     

Cobalt reduces nitrate inhibition of nodulation in mungbean (Vigna radiata)

 A cobalt-mediated decrease in ethylene production reduced the inhibition of nodulation by nitrate in Vigna radiata (mungbean). Nitrate increased the ethylene production in 5-day-old seedlings, while it caused a reduction in the nodulation status (nodule number and nodule weight) and nodule efficiency (acetylene reduction activity) in mungbean plants. The application of cobalt chloride inhibited nitrate-affected ethylene production and also decreased the inhibitory effect of nitrate on nodulation. The effect of cobalt was most marked on nodule number. Received: 6 August 1999     

冷却猪肉中假单胞菌生长预测模型的建立与验证

以从腐败猪肉中分离得到的假单胞菌P1,P2,P3,P4,P5,P6的混合培养物为受试菌液,应用Origin7．5软件拟合假单胞菌0-10℃下的生长情况。经比较发现,修正的Gompertz模型对假单胞菌生长曲线的拟合效果优于线性模型,R2均在0．96以上。应用平方根模型和Arrhenius模型对由修正的Gompertz模型得出的最大比生长速率进行拟合,所得Arrhenius模型的R2为0．9716,拟合效果优于平方根模型（R2为0．9326）。结果表明,所建二级模型,能真实快速有效地预测0-10℃冷藏条件下假单胞菌的生长。     

Chemisch-mineralogische und mikromorphologische untersuchung einer eutrophen (Ramann-) braunerde des Budapester Hügellandes

In spite of the fact that Ramann's concept of Braunerde was extensively used throughout the world, some pedogenic processes and soil properties which are important for the formation and existence of Brown Forest Soils (eutrophic brown earths) are still not well known. Hence, a soil was investigated which was classified as a “Braunerde” by Ramann in 1909. The main question was, whether there might be soil constituents such as inorganic amorphous substances (allophanes) which are able to stabilize the brown-earth fabric, or to inhibit clay migration. From chemical data as well as from the magnitude of the pH-dependent CEC, it was deduced that there are no appreciable amounts of allophanes within the soil. The fabric, however, seems to be stabilized by colloid-chemical flocculation of the clay particles caused by large amounts of carbonates and silicates deposited with the parent material (loess). The decalcified solum is still rich in silicates, especially sand and coarse-silt-sized micas and feldspars (60–200 and 20–60 μm fractions, respectively). Since - in comparison - loesses and loess-derived soils of the Central German mountain region contain less silicates, mainly in fine and medium silt fractions (2–6 and 6–20 μm diameter, respectively), the coarser-grained silicates were assumed to be important for maintaining the Ca²⁺ and Mg²⁺ saturation of the soil by continuous weathering and thus stabilizing the brown-earth fabric.Although the soil is saturated predominantly with Ca²⁺ and Mg²⁺ ions, clay migration proceeds within the upper horizons. This was shown by calculation of the amounts of clay formed by breakdown of micas originally present in the parent material (“clay formation balance”), as well as by micromorphological studies. Furthermore, micromorphological studies and x-ray diffraction data gave some evidence for the migration of preferably finest grained montmorillonitic clays (smectites) penetrated by organic substances (humus). This kind of “selective clay migration” was assumed to be caused by high Ca²⁺ (or Mg²⁺) concentrations in soil solution required for flocculation of humus-penetrated (humus-coated) smectites. From the occurrence of these “humus-smectites” the possibility was assumed that the soil studied has been developed from a former Chernozem type.Quantitatively, clay migration does not reach the amounts of clay formation (breakdown of micas) accompanied by precipitation of iron oxides on mineral surfaces (“Verbraunung”). Thus, the soil profile visually and macromorphologically clearly exhibits the features of brown earths. On the other hand, however, some clay migration was observed. Hence, the soil was classified as a “brown earth with some clay migration” (“schwach durchschlämmte Braunerde”).Judging from the results of the “clay formation balance” an appreciable pedogenic (autigenic) clay formation from weathering products of feldspars was excluded for the soil studied.     

Compost enhances plant resistance against the bacterial wilt pathogen Ralstonia solanacearum via up-regulation of ascorbate-glutathione redox cycle

The interactions between the pathogen Ralstonia solanacearum and potato Solanum tuberosum plants were studied to investigate the reactive oxygen species metabolic system and ascorbate (ASC)-glutathione (GSH) redox cycle in response to compost application. Single potato eyepieces were germinated and grown in pots containing sandy soil with or without compost at a rate of 7.5 g kg^?1 soil. Non-compost- and compost-treated plants (CTP) were inoculated with R. solanacearum 25 days after planting and then analyzed after 10 days, unless otherwise stated. The present results revealed that pathogen infection caused a remarkable decrease in plant growth related parameters and productivity and an increase in disease incidence. However, under these conditions compost had substantially improved plant growth and decreased disease incidence and bacterial population. R. solanacearum resulted in significant enhancement in the activities of NADPH oxidase, lipoxygenase, the production rate of superoxide and hydroxyl radicals, levels of hydrogen peroxide, membrane lipid peroxidation, and protein oxidation indicating the induction of oxidative stress in potato roots. However, the pathogen-mediated enhancement in indices of oxidative stress was considerably decreased by compost application, which enhanced the activities of ascorbate peroxidase (APX, EC 1.11.1.11), monodehydroascorbate reductase (MDHAR, EC 1.6.5.4), dehydroascorbate reductase (DHAR, EC 1.8.5.1) and glutathione reductase (GR, EC 1.6.4.2) in infected potato plants, implying a better ROS-scavenging activity. Data also indicated that there were general increases in ASC and GSH content in infected compost treated plants, but non-compost treated ones significantly had lower levels of such redox metabolites. In addition, significantly higher ratios of ASC/DHA (dehydroascorbate) and GSH/GSSG (glutathione disulphide) were generally found in CTP than in non-compost treated-ones. The obtained results suggest that compost provides effective protection against the Ralstonia bacterial pathogen via up-regulation of the capacity of the ASC-GSH cycle and modulation of the cellular redox status, thereby eliminating ROS damage and sustaining membrane stability.     

Comment on "Drought-induced reduction in global terrestrial net primary production from 2000 through 2009"

Zhao and Running (Reports, 20 August 2010, p. 940) reported a reduction in global terrestrial net primary production (NPP) from 2000 through 2009. We argue that the small trends, regional patterns, and interannual variations that they describe are artifacts of their NPP model. Satellite observations of vegetation activity show no statistically significant changes in more than 85% of the vegetated lands south of 70°N during the same 2000 to 2009 period.     

Determination of skin threshold concentration of an aqueous house dust mite allergen in normal dogs

Fifty-six healthy dogs with no known history of atopic disease to indoor allergens were skin tested with 6 different dilutions of an aqueous house dust mite extract. A concentration of 31.25 PNU/ml was found to be the maximum, nonirritating concentration. Thirty-two percent of the research dogs used had to be excluded because they failed to show reactions to any test dilution.     

New ELISA test for detection of bovine leukemia virus infections in cattle, using bacterially synthesized p24

A new ELISA test is described for the detection of antibodies to bovine leukemia virus protein p24. This test employs a bacterially synthesized p24 antigen which represents a hybrid protein consisting of beta-galactosidase and about 70% of the mature viral p24. The antigen preparation was enriched from Escherichia coli cells to 95% purity and was used for the detection of antibodies in cattle. In a selected set of 100 positive field sera, 97 could be verified by the new test.