Bestimmung der ernährungsphysiologischen Qualität von Öko-Produkten anhand des antioxidativen Potentials der Lebensmittel

Problemstellung: Die Diskussionen über sichere Lebensmittel (u.a. Rückstände von Pestiziden) im letzten Jahrzehnt hat das Verbraucherverhalten verändert. Viele Verbraucher bevorzugen ökologisch erzeugte Lebensmittel. Allerdings gibt es bis heute noch nicht ausreichende wissenschaftliche Daten dazu, ob ökologisch erzeugte Lebensmittel tatsächlich ernährungsphysiologisch hochwertiger sind als konventionell produzierte. Sekundären Pflanzenstoffen aus Obst und Gemüse (Carotinoiden, Polyphenole) kommt im Allgemeinen eine hohe gesundheitliche Bedeutung zu. Die in der Literatur beschriebenen protektiven Effekte auf entzündliche, atherosklerotische und tumorigene Prozesse werden u.a. auf ihr antioxidatives Potenzial zurückgeführt. Ziel der Studie war es daher zu untersuchen, ob sich der Gehalt an Carotinoiden und Polyphenolen und die antioxidative Kapazität in Lebensmitteln aus konventionellem und ökologischem Anbau unterscheidet. Darüber hinaus wurden drei humane Interventionsstudien durchgeführt, die klären sollten, ob die unterschiedlichen Anbauvarianten (ökologisch/konventionell) Einfluss auf die Bioverfügbarkeit der sekundären Pflanzenstoffe und den antioxidativen Status in vivo haben. Methodik: Im Rahmen des Projektes wurden Äpfel, Karotten und Weizenvollkorn der Erntejahre 2004, 2005 und 2006 aus kontrollierten Anbauversuchen untersucht. Die Gehalte an sekundären Pflanzenstoffen in vitro und in vivo wurden mittels HPLC/DAD/MS quantifiziert. Die antioxidativen Kapazitäten in vivo und in vitro wurden mit drei unterschiedlichen Testsystemen analysiert. Ergebnisse: Die Ergebnisse zeigen, dass die Anbauweise (ökologisch/konventionell) die Bildung von sekundären Pflanzenstoffen und das antioxidatives Potenzial in den untersuchten Lebensmitteln beeinflussen kann. Für die Öko-Produkte kann ein leicht höherer Gehalt und antioxidatives Potenzial bestimmt werden. In den durchgeführten Humanstudien, konnten keine Unterschiede in der Bioverfügbarkeit von Carotinoiden und Polyphenolen zwischen ökologisch und konventionell angebauten Äpfeln bzw. Karotten gezeigt werden. Schlussfolgerung: Die beobachteten Unterschiede im Gehalt an sekundären Pflanzenstoffen sowie im antioxidativen Potenzial zwischen den Anbauweisen sind klein und besitzen geringe ernährungsphysiologische Relevanz

The extrasolar planet Gliese 581 d: a potentially habitable planet? (Corrigendum to arXiv:1009.5814)

We report here that the equation for H2O Rayleigh scattering was incorrectly stated in the original paper [arXiv:1009.5814]. Instead of a quadratic dependence on refractivity r, we accidentally quoted an r^4 dependence. Since the correct form of the equation was implemented into the model, scientific results are not affected.Comment: accepted to Astronomy&Astrophysic

The habitability of a stagnant-lid Earth

Plate tectonics is a fundamental component for the habitability of the Earth. Yet whether it is a recurrent feature of terrestrial bodies orbiting other stars or unique to the Earth is unknown. The stagnant lid may rather be the most common tectonic expression on such bodies. To understand whether a stagnant-lid planet can be habitable, i.e. host liquid water at its surface, we model the thermal evolution of the mantle, volcanic outgassing of H$_2$O and CO$_2$, and resulting climate of an Earth-like planet lacking plate tectonics. We used a 1D model of parameterized convection to simulate the evolution of melt generation and the build-up of an atmosphere of H$_2$O and CO$_2$ over 4.5 Gyr. We then employed a 1D radiative-convective atmosphere model to calculate the global mean atmospheric temperature and the boundaries of the habitable zone (HZ). The evolution of the interior is characterized by the initial production of a large amount of partial melt accompanied by a rapid outgassing of H$_2$O and CO$_2$. At 1 au, the obtained temperatures generally allow for liquid water on the surface nearly over the entire evolution. While the outer edge of the HZ is mostly influenced by the amount of outgassed CO$_2$, the inner edge presents a more complex behaviour that is dependent on the partial pressures of both gases. At 1 au, the stagnant-lid planet considered would be regarded as habitable. The width of the HZ at the end of the evolution, albeit influenced by the amount of outgassed CO$_2$, can vary in a non-monotonic way depending on the extent of the outgassed H$_2$O reservoir. Our results suggest that stagnant-lid planets can be habitable over geological timescales and that joint modelling of interior evolution, volcanic outgassing, and accompanying climate is necessary to robustly characterize planetary habitability

Melting of a Two-component Source beneath Iceland

New trace element and Hf-Nd isotope data on post-glacial basalts from Iceland's main rift zones are used in conjunction with literature data to evaluate the relative importance of source heterogeneity and the melting process for the final melt composition. Correlations between Hf and Nd isotope compositions and trace element ratios indicate that at least two source components are sampled systematically as a function of the degree and pressure of melting beneath Iceland. Strong depletion in Rb, Ba, U and Th and enrichment in Nb and Ta compared with La in the most enriched samples from the Reykjanes Peninsula and Western Rift Zone suggests that the enriched source component is similar to ancient recycled enriched mid-ocean ridge basalt (E-MORB) crust. Highly incompatible trace element ratios such as Nb/La and Nb/U and Pb isotope ratios are variable across Iceland. This observation suggests that either the enriched component is intrinsically heterogeneous, or that there is a larger proportion of the enriched source component beneath the Southwestern Rift Zone compared with the Northern Rift Zone. The relative effect of source heterogeneity and melting on the final melt composition was evaluated with a one-dimensional polybaric melt mixing model in which accumulated melts from a depleted MORB mantle and a recycled E-MORB crust are mixed in different ways. Two styles of melt mixing were simulated: (1) complete mixing of melts with variable proportions of the depleted mantle and recycled E-MORB components; (2) incomplete mixing with a fixed initial proportion of the two source components. Calculated pressure-dependent compositional changes using these simple two-component melting models can explain the observed trends in trace element ratio and isotope ratio diagrams for Icelandic basalts, even in cases where conventional binary mixing models would require more than two source components. The example of Iceland demonstrates that melt mixing during extraction from the mantle is a key process for controlling the trace element and isotope variability observed in basaltic lavas and must be evaluated before inferring the presence of multiple source component

The unstable CO2 feedback cycle on ocean planets

Ocean planets are volatile-rich planets, not present in our Solar system, which are thought to be dominated by deep, global oceans. This results in the formation of high-pressure water ice, separating the planetary crust from the liquid ocean and, thus, also from the atmosphere. Therefore, instead of a carbonate-silicate cycle like on the Earth, the atmospheric carbon dioxide concentration is governed by the capability of the ocean to dissolve carbon dioxide (CO2). In our study, we focus on the CO2 cycle between the atmosphere and the ocean which determines the atmospheric CO2 content. The atmospheric amount of CO2 is a fundamental quantity for assessing the potential habitability of the planet's surface because of its strong greenhouse effect, which determines the planetary surface temperature to a large degree. In contrast to the stabilizing carbonate-silicate cycle regulating the long-term CO2 inventory of the Earth atmosphere, we find that the CO2 cycle feedback on ocean planets is negative and has strong destabilizing effects on the planetary climate. By using a chemistry model for oceanic CO2 dissolution and an atmospheric model for exoplanets, we show that the CO2 feedback cycle can severely limit the extension of the habitable zone for ocean planet

Clouds in the atmospheres of extrasolar planets. I. Climatic effects of multi-layered clouds for Earth-like planets and implications for habitable zones

The effects of multi-layered clouds in the atmospheres of Earth-like planets orbiting different types of stars are studied. The radiative effects of cloud particles are directly correlated with their wavelength-dependent optical properties. Therefore the incident stellar spectra may play an important role for the climatic effect of clouds. We discuss the influence of clouds with mean properties measured in the Earth's atmosphere on the surface temperatures and Bond albedos of Earth-like planets orbiting different types of main sequence dwarf stars.Comment: accepted for publication in A&

Геология и проект поисковых работ на золото-серебряное оруденение участка Эрек Майманджинской перспективной площади (Магаданская область)

Геология и проект поисковых работ на золото-серебряное оруденение участка Эрек Майманджинской перспективной площади (Магаданская область).Geology and the project of prospecting works for gold-silver mineralization of the Erek section of the Maymanzhinsky perspective area (Magadan Oblast)

DArT markers tightly linked with the Rfc1 gene controlling restoration of male fertility in the CMS-C system in cultivated rye (Secale cereale L.)

The Rfc1 gene controls restoration of male fertility in rye (Secale cereale L.) with sterility-inducing cytoplasm CMS-C. Two populations of recombinant inbred lines (RIL) were used in this study to identify DArT markers located on the 4RL chromosome, in the close vicinity of the Rfc1 gene. In the population developed from the 541×2020LM intercross, numerous markers tightly linked with the restorer gene were identified. This group contained 91 DArT markers and three SCARs additionally analyzed in the study. All these markers were mapped in the distance not exceeding 6 cM from the gene of interest. In the second mapping population (541×Ot1-3 intercross), only 9 DArT markers located closely to the Rfc1 gene were identified. Five of these DArT markers were polymorphic in both populations

Genetic dissection of photoperiod response based on GWAS of pre-anthesis phase duration in spring barley

Heading time is a complex trait, and natural variation in photoperiod responses is a major factor controlling time to heading, adaptation and grain yield. In barley, previous heading time studies have been mainly conducted under field conditions to measure total days to heading. We followed a novel approach and studied the natural variation of time to heading in a world-wide spring barley collection (218 accessions), comprising of 95 photoperiod-sensitive (Ppd-H1) and 123 accessions with reduced photoperiod sensitivity (ppd-H1) to long-day (LD) through dissecting pre-anthesis development into four major stages and sub-phases. The study was conducted under greenhouse (GH) conditions (LD; 16/8 h; ∼20/∼16°C day/night). Genotyping was performed using a genome-wide high density 9K single nucleotide polymorphisms (SNPs) chip which assayed 7842 SNPs. We used the barley physical map to identify candidate genes underlying genome-wide association scans (GWAS). GWAS for pre-anthesis stages/sub-phases in each photoperiod group provided great power for partitioning genetic effects on floral initiation and heading time. In addition to major genes known to regulate heading time under field conditions, several novel QTL with medium to high effects, including new QTL having major effects on developmental stages/sub-phases were found to be associated in this study. For example, highly associated SNPs tagged the physical regions around HvCO1 (barley CONSTANS1) and BFL (BARLEY FLORICAULA/LEAFY) genes. Based upon our GWAS analysis, we propose a new genetic network model for each photoperiod group, which includes several newly identified genes, such as several HvCO-like genes, belonging to different heading time pathways in barley