Water availability affects nectar sugar production and insect visitation of the cup plant Silphium perfoliatum L. (Asteraceae)

The perennial cup plant (Silphium perfoliatum L.) is considered as an alternative feedstock to maize for biogas plants. Due to its ecological advantages of an extensive management and function as food resource for pollinators, it can be grown in Ecological Focus Areas (EFAs) since 2018. However, studies at the Julius Kühn-Institute in Braunschweig (Germany) showed that the assumed advantage of the cup plant of a high drought tolerance could not be confirmed regarding aspects of crop production and yield. We complemented this experiment by assessing how different soil moisture conditions affect the production of floral resources and insect visitation. In 2014, we sampled three irrigated and three rainfed plots of the cup plant. We quantified the nectar volume and sugar mass per inflorescence, the number of inflorescences per plant and calculated the total nectar sugar production. We further counted insect visitation on the inflorescences. Due to reduced numbers of inflorescences per plant and an earlier harvest, the estimated nectar sugar production was 58 kg/ha regarding irrigated and 20 kg/ha regarding rainfed plots. Honeybee visitation per inflorescence was about twice as high in the irrigated plots. Furthermore, the early harvest is a disadvantage for wild pollinators with a late activity period.     

Metabolism of the pesticide metabolites 4-nitrophenol and 3,4-dichloroaniline in carrot (Daucus carota) cell suspension cultures

The metabolism of [ 14 C]-4-nitrophenol and [ 14 C]-3,4-dichloroaniline (the xenobiotics are degradation products of parathion and propanil, respectively) was studied in cell suspension cultures of carrot (Daucus carota L.). 4-Nitrophenol was transformed almost quantitatively to water-soluble conjugates with minor amounts of non-extractable residues. The conjugates identified were 1-(O-β-D-glucopyranosyl)-4-nitrobenzene and 1-(6′-O-malonyl-O-β-D-glucopyranosyl)-4-nitrobenzene. In addition, two unidentified metabolites were observed, possibly a disaccharide and another malonylated glycoside of 4-nitrophenol. Time-course studies demonstrated that 4-nitrophenol was rapidly taken up and conjugated; all metabolites remained associated with the cells rather than nutrient medium. 3,4-Dichloroaniline was transformed quantitatively to water-soluble conjugates and bound residues (3.6%). The water-soluble metabolites were identified as 6′-O-malonyl-N-(β-D-glucopyranosyl)-3,4-dichloroaniline, N-(β-D-glucopyranosyl)-3,4-dichloroaniline and N-malonyl-3,4-dichloroaniline. A time-course study showed that the glucosides were formed initially, then decreased, possibly due to hydrolysis. This decrease was paralleled by an increase of the main metabolite, N-malonyl-3,4-dichloroaniline, which was predominantly recovered from the medium.     

Metabolism of [ring-2,6-14]parathion in plant cell suspension cultures of carrot (Daucus carota), purple foxglove (Digitalis purpurea), soybean,thorn apple (Datura stramonium) and wheat (Triticum aestivum)

By means of standardized procedures, the metabolism of [ring-2,6-¹⁴C]-parathion was investigated in carrot (Daucus carota L.), purple foxglove (Digitalis purpurea L.), soybean (Glycine max Merrill cv. ?Mandarin’?, and Glycine max Merrill cv. ?Harosoy 63’? cultivated on B5 and Miller media, respectively), thorn apple (Datura stramonium L.), and wheat (Triticum aestivum L.) cell suspension cultures. In the wheat and soybean (Mandarin) cells only 2.9 and 8.9%, respectively, of the applied parthion remained unmetabolized after 48 h of incubation, while 51.2, 57.9, 60.3, and 62.4% of the unchanged parent were detected in the D. purpurea, D. Stramonium, carrot and soybean (Harosoy) cultures, respectively. In all suspensions, paraoxon and 4-nitrophenol were found as phase I metabolites, thus demonstrating that plant tissues can catalyse oxidative desulfuration and dearylation of parathion. 4-Nitrophenol was also glycosylated with glucose and possibly galactose. Further, as yet unidentified, metabolites indicated that bio-transformations had also occurred at the aromatic moiety. Large amounts of non-extractable residues were detected in the wheat suspension (38.3%), while the other cultures showed a lower incorporation of ¹⁴C into insoluble cell material (0.9-9.4%). For a prospective ecotoxicological evaluation of the metabolic fate of pesticides and xenobiotics in plants in general, the differential metabolic capacity of plant cell cultures and plants should be taken into account.     

Monoclonal Gammopathy in a Dog With Chronic Pyoderma

A monoclonal gammopathy composed of immunoglobulin G, with concurrent light-chain proteinuria and generalized lymph node plasmacytosis, was associated with chronic pyoderma in a dog. A uniform population of plasma cells was observed cytologically and histologically in multiple lymph node specimens. A diagnosis of monoclonal gammopathy of unknown significance was eventually made by exclusion of other known causes of monoclonal gammopathy, resolution after antibiotic therapy, and no evidence of lymphoproliferative disease after 11 months of follow-up and subsequent necropsy. This report expands the diagnostic considerations for monoclonal gammopathies in the dog.     

Einfluß steigender Stickstoffgaben auf den Kupferernährungszustand von Getreide

Effect of increasing nitrogen fertilization on copper demand in cereals Pot experiments were conducted with wheat (2 experiments) and spring barley (1 experiment) in a peat soil. Four N and four Cu fertilizer levels were chosen in such a way that, based on grain yield, within each N level there was a Cu deficient and a Cu sufficient treatment. For sufficient Cu supply, Cu level in soil and plant increased with increasing N level. Critical Cu concentrations in aboveground biomass at shooting [μg (g dw)^?1] were 3.5 (lowest N level = N₁) to 7.5 (highest N level = N₄) for grain production of wheat and barley, but for aboveground biomass of wheat at shooting they were only 2.6 (N₁) to 5.8 (N₄). Based on critical Cu concentration at different N levels, critical Cu/N ratios were determined. These were independent from N level, indicating that Cu remobilization in the older leaves is unlikely even at N deficiency. The high critical Cu concentrations at high N levels may be explained by an increased immobilization of Cu. Under Cu deficient conditions, Cu concentration did not increase with increasing N level. However, under Cu sufficient conditions, N concentration and Cu concentration of the plant increased with increasing N level. The increasing Cu uptake with increasing N level may be explained by the release of amines into the root apoplast and the rhizosphere. Particularly under Cu sufficient conditions, these may mobilize Cu by formation of soluble Cu-amine complexes.     

A well-preserved Archaeopteryx specimen with theropod features

A nearly complete skeleton of Archaeopteryx with excellent bone preservation shows that the osteology of the urvogel is similar to that of nonavian theropod dinosaurs. The new specimen confirms the presence of a hyperextendible second toe as in dromaeosaurs and troodontids. Archaeopteryx had a plesiomorphic tetraradiate palatine bone and no fully reversed first toe. These observations provide further evidence for the theropod ancestry of birds. In addition, the presence of a hyperextendible second toe blurs the distinction of archaeopterygids from basal deinonychosaurs (troodontids and dromaeosaurs) and challenges the monophyly of Aves.     

Retention of xenon in quartz and Earth's missing xenon

The reactivity of xenon with terrestrial oxides was investigated by in situ synchrotron x-ray diffraction. At high temperature (T > 500 kelvin), some silicon was reduced, and the pressure stability of quartz was expanded, attesting to the substitution of some xenon for silicon. When the quartz was quenched, xenon diffused out and only a few weight percent remained trapped in samples. These results show that xenon can be covalently bonded to oxygen in quartz in the lower continental crust, providing an answer to the missing xenon problem; synthesis paths of rare gas compounds are also opened.     

Climate-forced variability of ocean hypoxia

Oxygen (O(2)) is a critical constraint on marine ecosystems. As oceanic O(2) falls to hypoxic concentrations, habitability for aerobic organisms decreases rapidly. We show that the spatial extent of hypoxia is highly sensitive to small changes in the ocean's O(2) content, with maximum responses at suboxic concentrations where anaerobic metabolisms predominate. In model-based reconstructions of historical oxygen changes, the world's largest suboxic zone, in the Pacific Ocean, varies in size by a factor of 2. This is attributable to climate-driven changes in the depth of the tropical and subtropical thermocline that have multiplicative effects on respiration rates in low-O(2) water. The same mechanism yields even larger fluctuations in the rate of nitrogen removal by denitrification, creating a link between decadal climate oscillations and the nutrient limitation of marine photosynthesis.     

Morphology and Physiology of the Seminal Root System of Young Maize (Zea mays L.) Plants as Influenced by a Locally Restricted Nitrate Supply

In water culture the effect of a locally restricted NO₃ supply to the seminal root system of maize seedlings was studied. For this purpose plants were cultivated in containers with a wide-bore polyethylene tube positioned horizontally. Roots were suited through small holes in this tube and after sealing the holes with a non-toxic silicon putty, root segments in the tube could be exposed to a different nutrient solution from the rest of the root system in the outer compartment. In case of a locally restricted NO₃ supply (NO₃ was just supplied to the root segment within the tube), we observed an increase in root growth beginning at the fifth day after onset of the treatment. NO₃ uptake rate (¹⁵N) within the tube was significantly higher than in control plants (receiving NO₃ to the entire root system) as early as two days after onset of the treatment. One day later respiration (O₂ consumption) of the root segment exposed to NO₃ increased and at the same day we observed an accumulation of ¹⁴C activity (after pulse labelling of the shoots with ¹⁴CO₂) suggesting an increased phloem unloading. It is argued that this leads to the measured increase in IAA activity (Radio Immuno Assay) in the zone of NO₃ supply. Beginning at the fifth day we observed a stimulation of cell division rate (incorporation of ³H-methylthymidine), accompanied by an increase in length of first order lateral roots.     

Ti and Pb Concentrations in Rainwater-Fed Bogs in Europe as Indicators of Past Anthropogenic Activities

Chemical and physical analyses of dated ombrotrophic peat cores from 8 European regions were undertaken to determine the effect of forest clearances, farming, mining and smelting on the composition of atmospheric aerosols. Elemental concentrations in peat were determined using XRF and the mean concentrations of Ti and Pb in peat as well as Pb enrichment factors (Pb EFs) were calculated for each region and for different time periods (Roman Times, Dark Ages, Middle Ages, modern times). The results show that the concentration of Ti, Pb and the calculated Pb EFs closely follow changes in land use history extending back thousands of years. Concentrations of Ti, for example, reflect changing soil dust inputs in response to forest clearing and agriculture. Lead emissions are characterized by considerable continental-scale variations: elevated concentrations and EFs during the Roman Period at most sites, very high concentrations and EFs in the Harz Mountains during the Medieval period, and elevated to high concentrations and EFs during modern times at all sites. The findings indicate that peat cores from ombrotrophic bogs are useful not only for quantifying temporal changes in metal emissions, but also for identifying spatial variations on scales ranging from regional to global.