An advanced Jones calculus for the classification of periodic metamaterials

By relying on an advanced Jones calculus we analyze the polarization properties of light upon propagation through metamaterial slabs in a comprehensive manner. Based on symmetry considerations, we show that all periodic metamaterials may be divided into five different classes only. It is shown that each class differently affects the polarization of the transmitted light and sustains different eigenmodes. We show how to deduce these five classes from symmetry considerations and provide a simple algorithm that can be applied to decide by measuring transmitted intensities to which class a given metamaterial is belonging to only

NmPin from the marine thaumarchaeote Nitrosopumilus maritimus is an active membrane associated prolyl isomerase.

We cordially thank Alma Rute for excellent technical assistance and the DFG (GRK 1431-1 and 1431-2) for financial support (PB). We thank the Microscope and Histology Facility of the University of Aberdeen for providing their equipment. We also thank Jacob Hargreaves for proofreading the manuscript.Peer reviewedPublisher PD

Structural and phylogenetical analysis of the archaeal parvulin NmPin from Nitrosopumilus maritimus

Der cis/trans-Übergang von Xaa-Pro-Peptidbindungen benötigt bei moderaten Temperaturen einer Katalyse. Die Proteine, welche für diese Katalyse zuständig sind, die Peptidyl-Prolyl-cis/trans-Isomerasen (PPIasen) werden in drei sich in Primärsequenz, Sekundärstruktur und Funktionsweise unterscheidende Proteinfamilien eingeteilt. Zwei dieser Familien werden aufgrund ihrer Interaktion mit Immunsuppressiva als Immunophiline bezeichnet; die Cyclophiline binden Cyclosporin A, die FKBP (FK506 Bindeproteine) Tacrolimus. Diese Arbeit beschäftigt sich mit der dritten PPIase-Familie, den Parvulinen. Der bestuntersuchte Vertreter dieser Familie hPin1 ist sowohl beteiligt an der Ausbildung neurodegenerativer Erkrankungen, wie Morbus Alzheimer und Morbus Parkinson, als auch am Alterungsprozess und der Entstehung zahlreicher Tumorarten. Trotz einer Vielzahl struktureller Studien, an Parvulinen aus Eukarya, Bacteria und Fungi, blieb der Mechanismus der Peptidyl-Prolyl-cis/trans-Isomerisierung durch die Parvuline ungeklärt. Im letzten Jahrzehnt stieg die Zahl gelöster archaealer Genome sprunghaft an und einige dieser Genome trugen auch Parvuline des Par10-Typ (single domain Parvulin). Um einen Beitrag zur Auflösung des Isomerisierungsmechanismus der PPIC-Typ-PPIasen zu leisten wurde das Parvulin des einzigen kultivierbaren Archaeen welcher ein Parvulingen codiert, Nitrosopumilus maritimus, für diese Arbeit gewählt. Es konnte gezeigt werden, dass die archaealen und bakteriellen sdPar, sowohl durch phylogenetische Ansätze, als auch durch Experimente maschinellen Lernens voneinander unterschieden werden können. Des Weiteren wurde klar, dass die archaealen Parvuline ein echtes, „urtümliches“ Phylum darstellen und nicht etwa durch horizontalen Gentransfer aus Bacteria entstanden sind. Die verwendete Maximum Likelihood-Phylogenie lieferte in Kombination mit dem genetischen Hintergrund des archaealen Parvulingens sehr brauchbare evolutionäre Information. Die Datenbankanalysen ergaben zudem eine Korrelation zwischen hohen Lebensraumtemperaturen und geringen PPIase-Repertoire. Die NMR-Struktur von NmPin, mit einer Auflösung über alle Atome von 0,80 Å, wies das typische β3αβα2β-Parvulinfaltungsmuster, sowie ein, in früheren Studien bereits für Par14 und PrsA gezeigtes, Ladungsnetzwerk im aktiven Zentrum auf. Untersuchungen des elektrostatischen Potentials zeigten, das NmPin über eine positive geladene Interaktionsfläche verfügt, in deren Mitte ein reduziertes Cystein sitzt. Diese Beobachtung, sowie die Vorhersage eine möglichen Palmitylierung dieses Cysteins und immunobiochemische Experimente mit N. maritimus-Lysat, wiesen darauf hin, dass NmPin ein Membranprotein sein könnte.Cis/trans-isomerisation of Xaa-Pro-bonds depends on catalysis. The proteins responsible for this catalysis, the peptidyl-prolyl-cis/trans-isomerases (PPIases), are separated in three protein families, which differ in primary sequence, secondary structure and functionality. Two of these families are grouped as immunophilins because of their interaction with immunosuppressants; cyclophilins bind cyclosporin A, FKBPs (FK506 binding proteins) bind tacrolimus. This work deals with the third family of PPIases, the parvulins. The most studied parvulin, Pin1, is involved in the development of neurodegenerating diseases like Morbus Alzheimer and Morbus Parkinson as well as in aging and the development of many kinds of tumors. Despite numerous structural studies with parvulins from Eukarya, Bacteria and Fungi the mechanism of peptidyl-prolyl-cis/trans-isomerisation remained unsettled. During the last decade the number of solved archaeal genomes jumped up and some of these new genomes included Par10-type parvulins (single domain parvulins). To contribute in the elucidation of PPIC-type-PPIases isomerisation mechanism, the parvulin out of the only cultivatable Archaea including one, Nitrosopumilus maritimus, has been chosen for this work. The possibility to separate archaeal from bacterial sdPars by using phylogenetics as well as machine learning approaches has been shown. Furthermore the evolution of archaeal parvulins through events of horizontal gene transfer could be excluded. The applied maximum likelihood phylogeny combined with genetic background analysis of the archaeal parvulin gene delivered satisfying information. Searching data bases led to a correlation between high living temperatures and small PPIase repertoires. NmPin’s NMR structure, exhibiting a 0.80 Å resolution over all atoms, showed the parvulin typical β3αβα2β-fold as well as a charge relay system in the catalytic centre that Par14 and PrsA showed in former studies. Examining the electrostatic potential of NmPin’s surface illustrated a positively charged interface bearing a central reduced cysteine. This fact as well as the prediction of a potential palmitoylation of this cysteine and immunobiochemical approaches with N. maritimus lysate gave evidence for NmPin to be a membrane associated protein

Homogenization of resonant chiral metamaterials

Homogenization of metamaterials is a crucial issue as it allows to describe their optical response in terms of effective wave parameters as e.g. propagation constants. In this paper we consider the possible homogenization of chiral metamaterials. We show that for meta-atoms of a certain size a critical density exists above which increasing coupling between neighboring meta-atoms prevails a reasonable homogenization. On the contrary, a dilution in excess will induce features reminiscent to photonic crystals likewise prevailing a homogenization. Based on Bloch mode dispersion we introduce an analytical criterion for performing the homogenization and a tool to predict the homogenization limit. We show that strong coupling between meta-atoms of chiral metamaterials may prevent their homogenization at all.Comment: 8 pages, 7 figure

Evaluation of serological diagnostic test systems assessing the immune response to Japanese encephalitis vaccination.

A new commercial anti-Japanese encephalitis virus IgM and IgG indirect immunofluorescence test (IIFT) was evaluated for the detection of the humoral immune response after Japanese encephalitis vaccination. The IgM IIFT was compared to two IgM capture ELISAs and the IgG IIFT was analysed in comparison to a plaque reduction neutralization test (PRNT50) and an IgG ELISA. Moreover, the course of the immune reaction after vaccination with an inactivated JEV vaccine was examined. For the present study 300 serum samples from different blood withdrawals from 100 persons vaccinated against Japanese encephalitis were used. For the IgM evaluation, altogether 78 PRNT50 positive samples taken 7 to 56 days after vaccination and 78 PRNT50 negative sera were analyzed with the Euroimmun anti-JEV IgM IIFT, the Panbio Japanese Encephalitis – Dengue IgM Combo ELISA and the InBios JE Detect IgM capture ELISA. For the IgG evaluation, 100 sera taken 56 days after vaccination and 100 corresponding sera taken before vaccination were tested in the PRNT50, the Euroimmun anti-JEV IgG IIFT, and the InBios JE Detect IgG ELISA. The Euroimmun IgM IIFT showed in comparison to the Panbio ELISA a specificity of 95% and a sensitivity of 86%. With respect to the InBios ELISA, the values were 100% and 83.9%, respectively. The analysis of the Euroimmun IgG IIFT performance and the PRNT50 results demonstrated a specificity of 100% and a sensitivity of 93.8%, whereas it was not possible to detect more than 6.6% of the PRNT50 positive sera as positive with the InBios JE Detect IgG ELISA. Thus, the IIFT is a valuable alternative to the established methods in detecting anti-JEV antibodies after vaccination in travellers and it might prove useful for the diagnosis of acutely infected persons