Altered plasma lipidome profile of dairy cows with fatty liver disease.

Fatty liver disease is a common health problem of dairy cows occurring during the transition from pregnancy to lactation. It is a direct response to fat mobilization due to negative energy balance. Accumulation of lipids in the liver occurs if the uptake of non-esterified fatty acids by the liver exceeds the capacity of lipid oxidation or secretion by the liver. Currently, the diagnosis of fatty liver disease requires confirmation through biopsies to determine the hepatic lipid content. In view of this lack of a practical diagnostic tool, we compared the plasma lipidome of diseased dairy cows using liquid chromatography coupled to quadrupole time-of-flight mass spectrometry. Multivariate data analysis yielded 20 m/z values that were able to distinguish between dairy cows with no hepatic lipidosis and those exhibiting different stages of the disease. Based on the chromatography retention time and m/z ratios, we identified phosphatidylcholines with reduced plasma abundances in cows with fatty liver disease. The abundances of different bile acids tended to be increased. In addition, we detected two metabolites related to inflammation, resolvin E1 and palmitoyl-ethanolamine (PEA), which need to be further investigated in cattle. These results indicate that the measurement of specific representatives of phosphatidylcholines in plasma may provide a novel diagnostic biomarker of fatty liver disease in dairy cows.

Effects of Elevated Carbon Dioxide and Nitrogen Fertilization on Mycorrhizal Fine Roots and the Soil Microbial Community in Beech-Spruce Ecosystems on Siliceous and Calcareous Soil.

To study the responses of forests to global change, model ecosystems consisting of beech and spruce trees were maintained in open top chambers for 4 years under four conditions, namely with normal and elevated CO2 and with low and high nitrogen input, each replicated four times. Each open top chamber (height 3 m, diameter 3 m, soil depth 1.5 m) contained two separate soil compartments containing nutrient-poor siliceous and nutrient-rich calcareous soil. Here, we focus on the fine roots and the soil microbial community in these model ecosystems. At the time of planting, the fine roots were cut back according to forestry practice, and the newly formed roots were colonized by the indigenous soil microflora. After 4 years, the total biomass of fine roots, when averaged over all treatments, was almost the same in each of the two soil types; it was highest in the top 100 mm of soil (60%) and decreased sharply in deeper soil layers. Fungal biomass associated with the fine roots, consisting mainly of ectomycorrhizal fungi, was estimated using the ergosterol content as a marker. It was much higher in fine roots in the siliceous than in the calcareous soil, indicating considerably enhanced ectomycorrhiza formation in the nutrient-poor siliceous soil. Elevated atmospheric CO2 stimulated fine root production by ca. 85% and 43% in the top 100 mm of calcareous and siliceous soils respectively. Increased nitrogen input caused a slightly reduced production of fine root biomass in the calcareous soil but increased it by 33% in the siliceous soil. Marker substances for microorganisms were analyzed in the root-free soil. The amounts of carbon released by fumigation/extraction (a general marker for microbial biomass) and chitin (a marker for fungal biomass) were significantly higher in the top layer of the siliceous than of the calcareous soil, but they did not respond significantly to the treatments with elevated CO2 or the nitrogen fertilizer. The total concentration of the phospholipid fatty acids (PLFAs) and the number of the PLFAs did not differ between the two soil types. However, four of the eight most abundant PLFAs differed significantly between the two soil types. Principal component analysis revealed clearly separated clusters for the two soil types. Although analysis did not reveal any significant changes in response to the treatments, the concentration of the PLFA typical for ectomycorrhizal fungi was significantly higher under conditions of elevated CO2 in the nutrient-rich calcareous soil.

Biological activities of photoaffinity labeling analogues of kinins and their irreversible effects on kinin receptors.

Several analogues of bradykinin and [des-Arg9]bradykinin with potentially reactive groups have been tested for their biological activities. In these analogues, phenylalanine was replaced by the aromatic amino acid (4'-nitro)Phe, (4'-amino)Phe, (4'-azido)Phe, and (4'-diazonium)Phe, as well as with other residues. [Des-Arg9]bradykinin and the octapeptide analogues were tested on rabbit aorta strips, an assay organ containing the B1 receptor which is activated by the octapeptide [des-Arg9]bradykinin. Strips of rabbit jugular vein served as bioassays for bradykinin and the nonapeptide analogues, because the rabbit jugular vein bears the receptor B2 which is sensitive to bradykinin nonapeptides. The biological findings support the interpretation that kinins act on two different receptor types, since the potency orders of the analogues in the two bioassays are different. All potential photolabels retained reasonable affinities in the dark, except [(4'-azido)Phe8,des-Arg9]bradykinin, which, however, proved to be a weak and competitive antagonist of [des-Arg9]bradykinin on the rabbit aorta. Inactivation experiments with the unstable (4'-diazonium)Phe-containing peptides did not show any irreversible effect in the two bioassays. Photoaffinity labeling experiments with the azido and the nitro peptides gave irreversible and specific effects on both the rabbit aorta and the jugular vein. [(4'-Azido)Phe8,des-Arg9]bradykinin photolyzed at 365 nm on the rabbit aorta reduced the sensitivity of this tissue against [des-Arg9]bradykinin specifically to about one-third of its initial value. [(4'-Azido)Phe5]bradykinin reduced the sensitivity of the rabbit jugular vein to bradykinin by more than 50%. The observed irreversible effects were always loss of myotropic activity and never permanent contraction.