Einfluss des ökologischen Landbaus auf unterschiedliche Humuspools im Boden und Schlussfolgerungen zur Humusbilanzierung

Due to the results of organic matter balancing which showed a very high potential of soil organic matter accumulation in organic farming, a research project was started in spring 2005 with the objective to ascertain this hypothesis. Soil sampling was carried out on different organic and adjacent conventional farms in distinct regions of Ger-many. A comparison of the samples regarding Corg showed only minor differences between organic and conventional farms whereas the more sensitive indicators like Cmic and enzyme activities were more affected. However the main influencing factor of all these indicators in this investigation is soil texture. The cultivation system (inten-sive, extensive, stocking, crop rotation, tillage) is more important than the differentia-tion organic or conventional farming

Wirkungen differenzierter Bodenbearbeitungssysteme im Dauerversuch Scheyern

After a 12-year differing tillage in a 7-phase crop rotation with lay, potatoes, wheat, sunflowers, lay, wheat and rye it was found, that mouldboard-ploughing (P) resulted in less weed. Crop yields were as high as in the treatment with ploughing after lay and chiselling after potatoes and sunflowers (B). Lowest yields were obtained without ploughing but using the chisel (G). Weeds, esp. grasses, resulted in a huge competition for crops esp. after lay. Profit margins were highest in B due to lower expenditures for tillage and lowest in G. Soil organic carbon amounts differed by 1,5 t/ha and earthworm biomass by 0,25 t/ha between P and G after 12 years. It can be summed up for this experiment that G was not sustainable due to weeds and declining yields, and that B resulted in best economic profit, increasing SOM content and seems to be a sustainable compromise

The viral chemokine MCK-2 of murine cytomegalovirus promotes infection as part of a gH/gL/MCK-2 complex.

Human cytomegalovirus (HCMV) forms two gH/gL glycoprotein complexes, gH/gL/gO and gH/gL/pUL(128,130,131A), which determine the tropism, the entry pathways and the mode of spread of the virus. For murine cytomegalovirus (MCMV), which serves as a model for HCMV, a gH/gL/gO complex functionally homologous to the HCMV gH/gL/gO complex has been described. Knock-out of MCMV gO does impair, but not abolish, virus spread indicating that also MCMV might form an alternative gH/gL complex. Here, we show that the MCMV CC chemokine MCK-2 forms a complex with the glycoprotein gH, a complex which is incorporated into the virion. We could additionally show that mutants lacking both, gO and MCK-2 are not able to produce infectious virus. Trans-complementation of these double mutants with either gO or MCK-2 showed that both proteins can promote infection of host cells, although through different entry pathways. MCK-2 has been extensively studied in vivo by others. It has been shown to be involved in attracting cells for virus dissemination and in regulating antiviral host responses. We now show that MCK-2, by forming a complex with gH, strongly promotes infection of macrophages in vitro and in vivo. Thus, MCK-2 may play a dual role in MCMV infection, as a chemokine regulating the host response and attracting specific target cells and as part of a glycoprotein complex promoting entry into cells crucial for virus dissemination

Sediment contact test with Myriophyllum aquaticum (ISO/DIS 16191) : results of an international ring test

Although they are an important part of an aquatic ecosystem, dicotyledonous macrophytes are not yet part of the risk assessment of sediments or dredged material. A sediment contact test system with the dicotyledonous watermilfoil Myriophyllum aquaticum was established by the ecotoxicological laboratory of the German Federal Institute of Hydrology. This test procedure is now in the standardisation process within ISO. In the sediment contact test, Myriophyllum aquaticum whorls are exposed to environmental samples for ten days. The growth of Myriophyllum aquaticum in a test sample is compared with its growth in the control sample. Phytotoxic effects can be quantified as growth inhibition (%) relative to the control growth. Several laboratories from academia, industries and government participated in an interlaboratory ring test organized by the German Federal Institute of Hydrology. The ring test aimed at i) investigating the practicability and reproducibility of the sediment contact test, ii) validating the chosen endpoint, and iii) determining the response range of the reference substance functioning as positive control

M94 Is Essential for the Secondary Envelopment of Murine Cytomegalovirus ▿ † ‡

The gene M94 of murine cytomegalovirus (MCMV) as well as its homologues UL16 in alphaherpesviruses is involved in viral morphogenesis. For a better understanding of its role in the viral life cycle, a library of random M94 mutants was generated by modified transposon-based linker scanning mutagenesis. A comprehensive set of M94 mutants was reinserted into the MCMV genome and tested for their capacity to complement the M94 null mutant. Thereby, 34 loss-of-function mutants of M94 were identified, which were tested in a second screen for their capacity to inhibit virus replication. This analysis identified two N-terminal insertion mutants of M94 with a dominant negative effect. We compared phenotypes induced by the conditional expression of these dominant negative M94 alleles with the null phenotype of the M94 deletion. The viral gene expression cascade and the nuclear morphogenesis steps were not affected in either setting. In both cases, however, secondary envelopment did not proceed in the absence of functional M94, and capsids subsequently accumulated in the center of the cytoplasmic assembly complex. In addition, deletion of M94 resulted in a block of cell-to-cell spread. Moreover, the dominant negative mutant of M94 demonstrated a defect in interacting with M99, the UL11 homologue of MCMV