Mikrobiologische und biochemische Charakterisierung landwirtschaftlich genutzter Böden. I. Mitteilung: Die Ermittlung einer Bodenmikrobiologischen Kennzahl

Microbiological and biochemical characterization of agricultural soils Part. I. Determination of a soil microbiological index The intensity of soil microbial activity was determined by measuring the total microbial biomass, the activity of cellfree hydrolases (saccharase, protease and alkaline phosphatase) as well as mainly cellbound reductases (dehydrogenase and catalase). Testing 33 mixed samples of 11 different or differently treated, agricultural soils in Bavaria, a highly significant correlation (r = 0.77–0.99) between all individual microbiological soil properties was found. No correlations could be found with the additionally determined plate counts of bacteria or with nitrifications tests. This close relation between the tested biomass and enzyme activities could be used for calculating an over-all index (Bodenmikrobiologische Kennzahl) of soil microbial activity by transforming and combining the individual analytical soil properties according to the following equation:      

大气氨及环境高温对蛋鸡的热损失与呼吸形式的影响

将白莱克亨蛋鸡分别受10ppm和60ppm大气氨作用30天后,放入含有5ppm大气氨的环境下恢复7天,然后将其放人环境空气温度分别为25℃、29℃、30℃和37℃的直接测热室内,测得其热损失及呼吸频率等数据。 实验结果表明,受60ppm大气氨作用和受10ppm大气氨作用的蛋鸡,具有相似的潜热损失率。鸡的潜热损失随着环境温度的升高、呼吸频率的加快而增大。对于给定的环境温度,呼吸频率的变化对潜热损失没有明显的影响。     

Auswirkungen der Gamma-Bestrahlung und Pasteurisierung von Klärschlamm auf seine mikrobiellen Eigenschaften und die Mineralisierung im Boden

Effect of γ-irradiation and pasteurization of sewage sludge to the microbiological properties and the mineralization in soil Hygienic aspects of sewage sludge application in agricultural practice are of increasing importance. Because parasites are extremely sensitive to γ-irradiation a dose of 300 krad is equivalent to pasteurization. The total bacteria count of the sewage sludge is reduced by this dosage by 90 to 99%. Enzymic activity is reduced after radiation at a rate of about 39%. Especially amylase, catalase, and alkaline phosphatase are extremely sensitive to irradiation. Mineralization studies of sewage sludge with different pretreatments in different soil types indicated no significant differences.     

Untersuchungen über die toxische Wirkung der in Siedlungsabfällen häufigen Schwermetalle auf die Bodenmikroflora

The toxic effects of heavy metals, commonly found in urban wastes on the soil microflora In several series the influence of soluble salts of Cd, Cr, Zn, Cu, Ni and Hg in various concentrations was tested on the development of bacteria and fungi in cultural studies and in soil model systems. In addition the changes in microbial biomass, in the activity of oxidoreductases and hydrolases, and in nitrification were measured in five soils. Comparison of the results of bacteria-plate-counts in the presence of heavy metals in agar-media and in soils demonstrated that all tested elements have a more toxic effect on isolated soil microorganisms under culture conditions than when tested after heavy metal application to soils. Beside Hg, eucaryotic soil fungi proved to be 10 – 50 fold more resistant to heavy metals in vitro as well as in situ. For calculating the effect of heavy metals on soil microbial activity soil enzymatic methods are not reliable and can be used only to some extent, because some cellfree encymes in the soil are activated or inactivated immediately by heavy metals. In long-term experiments, the microbial biomass and nitrification in soil is not significantly influenced by the elements Cd, Cu and Ni in the concentration range of the tolerable limit content. In contrast, Cr, Zn and Hg reduced these microbiological properties more or less distinctly.     

Balancing selection at the prion protein gene consistent with prehistoric kurulike epidemics

Kuru is an acquired prion disease largely restricted to the Fore linguistic group of the Papua New Guinea Highlands, which was transmitted during endocannibalistic feasts. Heterozygosity for a common polymorphism in the human prion protein gene (PRNP) confers relative resistance to prion diseases. Elderly survivors of the kuru epidemic, who had multiple exposures at mortuary feasts, are, in marked contrast to younger unexposed Fore, predominantly PRNP 129 heterozygotes. Kuru imposed strong balancing selection on the Fore, essentially eliminating PRNP 129 homozygotes. Worldwide PRNP haplotype diversity and coding allele frequencies suggest that strong balancing selection at this locus occurred during the evolution of modern humans.