In-vitro-Erosion von menschlichen Milchzähnen verursacht durch Zitronensäure, vergleichend gemessen mit Profilometer und konfokalem Laser Scanning Mikroskop

Erosion ist ein irreversibler Zahnhartsubstanzverlust durch Kontakt mit extrinsischen und/oder intrinsischen Säuren ohne Beteiligung von Bakterien. Das konfokale Laser Scanning Mikroskop (CLSM) scheint geeignet, Substanzverlust durch Erosion darzustellen und zu quantifizieren. Das Verfahren wird in dieser In-vitro-Studie im Vergleich zur Profilometrie angewandt, um Erosionstiefen an Milchzähnen zu messen. Aus Milchfrontzähnen wurden 45 Proben hergestellt, die Oberflächen poliert und in 6 Versuchsgruppen aufgeteilt. Vor den Erosionsversuchen wurde der quadratische Mittenrauwert Rq mit Profilometer und CLSM ermittelt. Anschließend wurden auf der Labialseite der Proben abgeklebte Fenster mit 0,3%iger Zitronensäure (pH 3,2) 10, 20 und 30 Minuten erodiert. Die Kontrollgruppen wurden 10, 20 und 30 min mit destilliertem Wasser behandelt. Mittels Profilometrie und CLSM wurde die Gesamthöhe des Primärprofils Pt als Erosionstiefe ermittelt. Destilliertes Wasser verursachte keine Erosion. Hier wurde erneut Rq mittels Profilometrie und CLSM ermittelt. Mittels CLSM wurden zusätzlich die Tiefe der Profilometermessspur und die Volumenverluste nach Erosion ermittelt. Die Ergebnisse zeigen einen signifikanten Substanzverlust nach 10, 20 und 30 min Erosion mit Zitronensäure. Je länger die Erosionszeit, desto größer ist die Erosionstiefe bei beiden Messgeräten bzw. der Volumenverlust bei CLSM, desto ausgeprägter sind die Unterschiede der Messwerte zwischen Profilometer und CLSM und desto tiefer ist die Profilometermessspur, die das Profilometer auf den erodierten Bereichen hinterlässt. Aus diesen Ergebnissen kann geschlussfolgert werden, dass CLSM im Gegensatz zur Profilometrie ein geeigneteres Verfahren zur Ermittlung der Erosionstiefen und Volumenverluste auf durch Säureeinwirkung erweichten Oberflächen darstellt

Effects of Drought and Heat on Photosynthetic Performance, Water Use and Yield of Two Selected Fiber Hemp Cultivars at a Poor-Soil Site in Brandenburg (Germany)

Hemp currently regains certain importance as fiber, oil and medical crop not least because of its modest requirements of biocides, fertilizer and water. During recent years, crops were exposed to a combination of drought and heat, even in northern Central-Europe. Dynamic responses of photosynthesis and stomatal conductance to these stresses and their persistent effects had been studied, if at all, in controlled environment experiments. Comprehensive field studies on diurnal and long-term net photosynthesis and gas exchange, and yield properties of hemp during a drought prone, high-temperature season in northern Central-Europe are obviously missing. Thus, in whole season field trails, the essential actual physiological (rates of net photosynthesis and transpiration, stomatal conductance, water use efficiencies, ambient and internal CO2 concentrations) and the yield performance of modern high-yielding multi-purpose hemp cultivars, ‘Ivory’ and ‘Santhica 27’, were evaluated under extreme environmental conditions and highly limited soil water supply. This provides comprehensive information on the usability of these cultivars under potential future harsh production conditions. Plants of both cultivars differentially cope with the prevailing climatic and soil water conditions. While ‘Ivory’ plants developed high rates of CO2 gain and established large leaf area per plant in the mid-season, those of ‘Santhica 27’ utilized lower CO2 uptake rates at lower leaf area per plant most time. This and the higher germination success of ‘Santhica 27’ resulted in nearly twice the yield compared to ‘Ivory’. Although stomatal control of CO2 gain was pronounced in both cultivars, higher stomatal limitations in ‘Ivory’ plants resulted in higher overall intrinsic water use efficiency. Cultivation of both hemp cultivars with only basic irrigation during seed germination was successful and without large effects on yield and quality. This was valid even under extremely hot and dry climatic conditions in northern Central Europe

Study of Water Productivity of Industrial Hemp under Hot and Dry Conditions in Brandenburg (Germany) in the Year 2018

Hemp (Cannabis sativa L.) is a high-yielding multi-purpose crop, but its hydrological functioning is poorly understood. Studies on the interception processes in hemp have been lacking so far. This study contributes to the understanding of the influences of evaporation of intercepted water and other hydrological fluxes within plants of two cultivars, “Santhica 27” and “Ivory”, on the water productivity. To determine water productivity and evaporation from interception, field measurements were conducted on plants of both cultivars at different stages of development. Precipitation (P), throughfall (TF), transpiration (T), and volumetric water content (VWC) were measured along with leaf area index (LAI) and yield of selected plant components. For the entire vegetation period, the cumulative P of 44 mm was converted into 13 mm TF (30%). The inferred evaporation of intercepted water (I) was high at 31 mm (71%). For the assessment water fluxes, the evaporation of intercepted water must be considered in the decision-making process. Besides the LAI, the plant architecture and the meteorological conditions during the cropping cycle seem to be the main factors determining I in the case of plants of both cultivars. Water productivity (WPDM) of the whole plant varied between 3.07 kg m−3 for Ivory and 3.49 for Santhica 27. In the case of bast yield, WPDM was 0.39 kg m-3 for Santhica 27 and 0.45 kg m−3 for Ivory. After the propagation of the uncertainties, the bandwidth of the WPDM of the whole plant was between 0.42 kg m−3 and 2.57 kg m−3. For bast fiber a bandwidth of the WP between 0.06 kg m−3 and 0.33 kg m−3 was calculated. The results show furthermore that even with a precise examination of water productivity, a high bandwidth of local values is revealed on different cultivars. However, generic WP values for fiber crops are not attainable

The machinery underlying malaria parasite virulence is conserved between rodent and human malaria parasites

Sequestration of red blood cells infected with the human malaria parasite Plasmodium falciparum in organs such as the brain is considered important for pathogenicity. A similar phenomenon has been observed in mouse models of malaria, using the rodent parasite Plasmodium berghei, but it is unclear whether the P. falciparum proteins known to be involved in this process are conserved in the rodent parasite. Here we identify the P. berghei orthologues of two such key factors of P. falciparum, SBP1 and MAHRP1. Red blood cells infected with P. berghei parasites lacking SBP1 or MAHRP1a fail to bind the endothelial receptor CD36 and show reduced sequestration and virulence in mice. Complementation of the mutant P. berghei parasites with the respective P. falciparum SBP1 and MAHRP1 orthologues restores sequestration and virulence. These findings reveal evolutionary conservation of the machinery underlying sequestration of divergent malaria parasites and support the notion that the P. berghei rodent model is an adequate tool for research on malaria virulence