Der Wasserhaushalt vonAvena sativa L. bei steigender Mineralvolldüngung

Zusammenfassung 1. Die Beeinflussung des Wasserhaushaltes durch gesteigerte Mineralvolldüngung wurde an Freilandkulturen von Avena sativa L. untersucht.2. Durch die Düngung bildeten sich Unterschiede im Bestandsklima aus, die bereits inmitten der nur 2,5 m² großen Versuchsparzellen zur Geltung kamen. Sie ließen sich variationsstatistisch erfassen und absichern. Die Luft blieb im Bestand mit höherer Düngung kühler und feuchter.3. Das üppigere Wachstum gedüngter Kulturen erhöhte den Wasserverbrauch pro Flächeneinheit und führte damit zu einer Erniedrigung des Bodenwassergehaltes, die größer als unter ungedüngten Kulturen war.4. Gedüngte Haferpflanzen wiesen einen höheren Wassergehalt und ein höheres Wassersättigungsdefizit am Mittag auf.5. Ansteigende, jedoch das Optimum nicht überschreitende Düngung bewirkte eine Herabsetzung der Transpiration (pro Gramm Frischgewicht).

---

Summary 1. The effect of increasing amounts of mineral fertilizers on the plant-water relationship of Avena sativa L. was analysed in field trials.2. As an effect produced by different grades of fertilization different microclimates in the stands have been established even in small plots of only 2.5 m². The air in the stands with higher fertilization was cooler and moister.3. The more vigorous growth on fertilized plots increased water consumption per area and consequently decreased the water content of the soil.4. Water content and water deficit of leaf laminae were higher in fertilized than in not fertilized plants.5. Increasing amounts of fertilizers not transgressing the optimum caused a decrease of transpiration (per gram fresh weight).

---

---

Teil einer Dissertation an der Naturwissenschaftlich-Philosophischen Fakultät der Justus Liebig-Universität Gießen     

The Bay of Bengal exposes abundant photosynthetic picoplankton and newfound diversity along salinity-driven gradients

The Bay of Bengal (BoB) is a 2,600,000 km² expanse in the Indian Ocean upon which many humans rely. However, the primary producers underpinning food chains here remain poorly characterized. We examined phytoplankton abundance and diversity along strong BoB latitudinal and vertical salinity gradients—which have low temperature variation (27–29°C) between the surface and subsurface chlorophyll maximum (SCM). In surface waters, Prochlorococcus averaged 11.7 ± 4.4 × 10⁴ cells ml⁻¹, predominantly HLII, whereas LLII and ‘rare’ ecotypes, HLVI and LLVII, dominated in the SCM. Synechococcus averaged 8.4 ± 2.3 × 10⁴ cells ml⁻¹ in the surface, declined rapidly with depth, and population structure of dominant Clade II differed between surface and SCM; Clade X was notable at both depths. Across all sites, Ostreococcus Clade OII dominated SCM eukaryotes whereas communities differentiated strongly moving from Arabian Sea-influenced high salinity (southerly; prasinophytes) to freshwater-influenced low salinity (northerly; stramenopiles, specifically, diatoms, pelagophytes, and dictyochophytes, plus the prasinophyte Micromonas) surface waters. Eukaryotic phytoplankton peaked in the south (1.9 × 10⁴ cells ml⁻¹, surface) where a novel Ostreococcus was revealed, named here Ostreococcus bengalensis. We expose dominance of a single picoeukaryote and hitherto ‘rare’ picocyanobacteria at depth in this complex ecosystem where studies suggest picoplankton are replacing larger phytoplankton due to climate change.     

Lead transport in IEC-6 intestinal epithelial cells

This study evaluated the use of IEC-6 cells as a model for studying lead (Pb) transport by intestinal epithelial cells (IECs) and examined potential transport mechanisms for Pb uptake and extrusion. Pb accumulation in IEC-6 cells exposed to 5 and 10 μM Pb for up to 60 min was time- and dose-dependent. Reduction of incubation temperature significantly reduced the total cellular Pb content of IEC-6 cells. Simultaneous exposure of cells to zinc (Zn) and Pb resulted in decreased total cellular Pb contents compared to total cellular Pb contents of cells exposed to Pb only. IEC-6 cells treated with ouabain (1 mM) or sodium azide (1 mM) and 5 μM Pb accumulated more Pb than cells exposed to Pb only. Cells treated withp-chloromercuribenzensulfonic acid (50 μM),p-chloromercuribenzoic acid (50 μM), or iodoacetimide (50 μM) accumulated less Pb than cells treated with Pb only. We conclude that Pb uptake by IEC-6 cells depends on the extracellular Pb concentration. Our data suggest that the mechanism of Pb uptake by IECs is complex, and that Pb transport in IEC-6 cells is time- and temperature-dependent, involves sulfhydryl groups, and is decreased by the presence of Zn. Extrusion of Pb is at least partially dependent on metabolic energy.     

Combination of high-performance liquid chromatography and thin-layer chromatography separation of five adducted nucleotides isolated from liver resulting from intraperitoneal administration with 7H-dibenzo[c,g]carbazole to mice

7H-Dibenzo[c,g]carbazole, DBC, is a potent environmental liver carcinogen. Liver DNA from mice treated with DBC exhibited seven distinct DBC-DNA adducts as detected by ³²P-postlabeling using multidimensional TLC. To improve quantitation and chemically characterize the adducts, DNA samples were hydrlyzed, ³²P-postlabeled and the adducts were separated from the unadducted normal nucleotides on TLC using a D1 solvent, 0.65 M sodium phosphate (pH 6.8). Adducts were eluted from the TLC plates with 4.0 M pyridinium formate, concentrated, resuspended in 50% aqueous methanol and injected onto the HPLC; five individual adduct peaks were resolved and collected by this method. This approach will prove useful to decrease analysis time and improve chemical characterization of tightly clustered DNA adducts generated in vivo.