Computational studies of biomembrane systems: Theoretical considerations, simulation models, and applications

This chapter summarizes several approaches combining theory, simulation and experiment that aim for a better understanding of phenomena in lipid bilayers and membrane protein systems, covering topics such as lipid rafts, membrane mediated interactions, attraction between transmembrane proteins, and aggregation in biomembranes leading to large superstructures such as the light harvesting complex of green plants. After a general overview of theoretical considerations and continuum theory of lipid membranes we introduce different options for simulations of biomembrane systems, addressing questions such as: What can be learned from generic models? When is it expedient to go beyond them? And what are the merits and challenges for systematic coarse graining and quasi-atomistic coarse grained models that ensure a certain chemical specificity

Trenger Luftforsvaret militære flyteknikere?

Forsvaret bemannes i dag av omlag 1/3 sivilt- og 2/3 militært ansatte. Mange avdelinger består av en blanding av sivilt og militært personell. Innretningen er i stort uendret fra mobiliseringsforsvaret, men uten at det synes å foreligge kvalitative og dokumenterte vurderinger av hensiktsmessigheten av en slik bemanningsstrategi i innsatsforsvaret. Denne oppgaven undersøker fordeler og ulemper forbundet med enten sivile eller militære flyteknikere i bemanningen av Luftforsvarets flyvedlikeholdsavdelinger. Den primære oppgaven til disse avdelingene er å sørge for at fly og helikoptre er operativt tilgjengelige for nasjonale fredstidsoperasjoner, styrkeproduksjon av besetninger, og innsats i krise, krig og internasjonale operasjoner. Ved hjelp av en kvalitativ metode analyseres to hovedforhold: Hvordan sivile flyteknikere ansatt på Verkstedoverenskomsten for Forsvaret (OVK-personell) og yrkesmilitære flyteknikere (teknisk befal) virker inn på effektiviteten i den tekniske fredstidsdriften av Luftforsvarets fly og helikoptre, og hvordan disse personellkategoriene virker inn på innsatsevnen til Luftforsvarets strukturelementer i operasjoner. Effektiviteten i normaldriften undersøkes som et resultat av forholdet mellom ressursinnsats og produksjonsverdi. Til tross for at den totale ressursinnsatsen forbundet med personellkategoriene i et livsløpsperspektiv ikke blir fullstendig kartlagt i denne oppgaven, er det vist at anvendelse av teknisk befal medfører lavere kostnader enn anvendelse av OVK-personell forutsatt samme aktivitetsmønster. Produksjonsverdien forbundet med tekniske befal er totalt sett høyere enn for OVK-personell. Dette skyldes ulikheter i seleksjon, utdanning, og ansettelsesvilkår og avtaleverk. Funnene knyttet til ressursinnsats og produksjonsverdi i normaldriften utfordrer et av Forsvarsdepartementets viktigste argumenter for tilsetting av sivile; nemlig kosteffektivitet. Analysen av det andre hovedforholdet dreier seg om hensiktsmessigheten av personellkategoriene gitt Luftforsvarets innsatskonsept, gitt endringer i selve flyvedlikeholdet, og gitt militære trusler mot flybasene. Til tross for at OVK-personell kan disponeres til tjeneste i internasjonale operasjoner, synes gripbarheten for denne personellkategorien i realiteten å være lavere enn tilfellet er for tekniske befal; særlig i en nasjonal krisesituasjon. Overgangen fra freds- til krise- eller krigsvedlikehold påvirker imidlertid ikke hensiktsmessigheten av de to personellkategoriene i bemanningen av avdelingene. Med utgangspunkt i ulike militære trusler mot flybaser i krise, krig og internasjonale operasjoner konkluderer analysen med at teknisk befal er mest hensiktsmessig av folkerettslige, taktiske og praktiske militære grunner. Denne personellkategorien bidrar altså totalt sett til bedre innsatsevne for Luftforsvarets strukturelementer i operasjoner enn OVK-personell

Translocation of proteins into isolated chloroplasts requires cytosolic factors to obtain import competence

The precursor form of the major-harvesting chlorophyll a/b-binding protein (pLHCP) of chloroplast thylakoids was overproduced in E. coli cells and used to study the influence of soluble factors on post-translational protein import into isolated pea chloroplasts. pLHCP solubilised in 8 M urea was not import-competent. However, if pLHCP was dialysed in the presence of soluble proteins (leaf extract) after urea treatment, import competence was gained. Dialysis of pLHCP in the presence of leaf extract alters its protease sensitivity. Stremai proteins, ovalbumin, trypsin inhibitor or chloroplast lipids could not produce import competence of pLHCP. Two components from leaf extract seem to be necessary, one of which can be mimicked by purified hsc 70, the other one requiring ATP. We conclude that soluble proteins from outside the stromal compartment are necessary for post-translational import of proteins into chloroplasts

Klimagase und deren Minderung bei der Milchproduktion

Sources of greenhouse gas (GHG) emission of milk production were analysed on organic and conventional dairy farms from cradle to farm gate and resulted in a mean of ca. 1 kg CO2 eq kg ECM-1 independent of the farm system. When calculated according to dry matter intake of the cows, mean percentages of GHG emissions from enteric fermentation on organic or conventional farms were 31 or 42 % from the complete product related emissions from milk production from cradle to farm gate, respectively. When feed quality parameters were considered in calculation, enteric methane production increased considerably with higher fibre contents in feedstuffs. This was especially important at lower milk yields. On the 44 farms that were analysed, minimal potential GHG emissions from enteric fermentation on the herd level were 0.39 (organic farm) and 0.32 kg CO2 eq kg ECM-1 (conventional farm). This is proposed as unavoidable range for milk from intensive conventional and organic dairy production. GHG emissions from replacement animals and from feedstuff production are also part of the dairy systems. These emissions can only partly be reduced by feedstuff man-agement, manure management and technical measures, e.g. slurry cover, biogas production. Efficiency gains in all steps of the process chain by appropriate manage-ment appear to be most important for (reliably) reducing GHG emissions, e.g., by optimal feed quality and its related good milk yields and healthy and long living cows

An unusual role for the phytyl chains in the photoprotection of the chlorophylls bound to Water-Soluble Chlorophyll-binding Proteins

Water-Soluble Chlorophyll Proteins (WSCPs) from Brassicaceae are non-photosynthetic proteins which tetramerize upon binding four chlorophyll (Chl) molecules. The bound Chls are highly photostable, despite the lack of bound carotenoids known, in Chl-containing photosynthetic proteins, to act as singlet oxygen and Chl triplet (3Chl) quenchers. Although the physiological function of WSCPs is still unclear, it is likely to be related to their biochemical stability and their resistance to photodegradation. To get insight into the origin of this photostability, the properties of the 3Chl generated in WSCPs upon illumination were investigated. We found that, unlike the excited singlet states, which are excitonic states, the triplet state is localized on a single Chl molecule. Moreover, the lifetime of the 3Chl generated in WSCPs is comparable to that observed in other Chl-containing systems and is reduced in presence of oxygen. In contrast to previous observations, we found that WSCP actually photosensitizes singlet oxygen with an efficiency comparable to that of Chl in organic solvent. We demonstrated that the observed resistance to photooxidation depends on the conformation of the phytyl moieties, which in WSCP are interposed between the rings of Chl dimers, hindering the access of singlet oxygen to the oxidizable sites of the pigments

Optimierungsansätze zur Verbesserung von Nachhaltigkeit, Ressourceneffizienz und Tierwohl in ökologischen und konventionellen Betrieben im Netzwerk Pilotbetriebe

In a network of organic and conventional pilot farms with dairy and/or arable production in Germany (www.pilotbetriebe.de) aspects of sustainability, resource efficiency, animal health and welfare and economic aspects are analysed. This is based on on-farm assessments and on whole farm modelling. In the first interdisciplinary workshops on the project farms results were presented and scenarios were developed in a participatory approach by scientists, consultants and farmers to improve N, P and land use efficiency as well as dairy health and welfare. Typical areas of action to optimize sustainability in these aspects were identified on the farms, e.g., complete accounting of manure N (N balance), enrichment of crop rotations with clover grass and cover crops (humus balance), improving forage quality (productivity, nutritional imbalances), improvement of housing conditions and grazing access (animal health and welfare). Systematic integration and detection of interconnectedness of environmental performance of production, animal welfare, resource efficiency and productivity result in a new quality in development of farm concepts

Combined fit to the spectrum and composition data measured by the Pierre Auger Observatory including magnetic horizon effects

The measurements by the Pierre Auger Observatory of the energy spectrum and mass composition of cosmic rays can be interpreted assuming the presence of two extragalactic source populations, one dominating the flux at energies above a few EeV and the other below. To fit the data ignoring magnetic field effects, the high-energy population needs to accelerate a mixture of nuclei with very hard spectra, at odds with the approximate E$^{-2}$ shape expected from diffusive shock acceleration. The presence of turbulent extragalactic magnetic fields in the region between the closest sources and the Earth can significantly modify the observed CR spectrum with respect to that emitted by the sources, reducing the flux of low-rigidity particles that reach the Earth. We here take into account this magnetic horizon effect in the combined fit of the spectrum and shower depth distributions, exploring the possibility that a spectrum for the high-energy population sources with a shape closer to E$^{-2}$ be able to explain the observations