Induced gamma-band activity is related to the time point of object identification

Peer reviewedPostprin

What’s in a name? How organelles of endosymbiotic origin can be distinguished from endosymbionts

Mitochondria and plastids evolved from free-living bacteria, but are now considered integral parts of the eukaryotic species in which they live. Therefore, they are implicitly called by the same eukaryotic species name. Historically, mitochondria and plastids were known as “organelles”, even before their bacterial origin became fully established. However, since organelle evolution by endosymbiosis has become an established theory in biology, more and more endosymbiotic systems have been discovered that show various levels of host/symbiont integration. In this context, the distinction between “host/symbiont” and “eukaryote/organelle” systems is currently unclear. The criteria that are commonly considered are genetic integration (via gene transfer from the endosymbiont to the nucleus), cellular integration (synchronization of the cell cycles), and metabolic integration (the mutual dependency of the metabolisms). Here, I suggest that these criteria should be evaluated according to the resulting coupling of genetic recombination between individuals and congruence of effective population sizes, which determines if independent speciation is possible for either of the partners. I would like to call this aspect of integration “sexual symbiont integration”. If the partners lose their independence in speciation, I think that they should be considered one species. The partner who maintains its genetic recombination mechanisms and life cycle should then be the name giving “host”; the other one would be the organelle. Distinguishing between organelles and symbionts according to their sexual symbiont integration is independent of any particular mechanism or structural property of the endosymbiont/host system under investigation

Blasticidin-S deaminase, a new selection marker for genetic transformation of the diatom Phaeodactylum tricornutum

Most genetic transformation protocols for the model diatom Phaeodactylum tricornutum rely on one of two available antibiotics as selection markers: Zeocin (a formulation of phleomycin D1) or nourseothricin. This limits the number of possible consecutive genetic transformations that can be performed. In order to expand the biotechnological possibilities for P. tricornutum, we searched for additional antibiotics and corresponding resistance genes that might be suitable for use with this diatom. Among the three different antibiotics tested in this study, blasticidin-S and tunicamycin turned out to be lethal to wild-type cells at low concentrations, while voriconazole had no detectable effect on P. tricornutum. Testing the respective resistance genes, we found that the blasticidin-S deaminase gene (bsr) effectively conferred resistance against blasticidin-S to P. tricornutum. Furthermore, we could show that expression of bsr did not lead to cross-resistances against Zeocin or nourseothricin, and that genetically transformed cell lines with resistance against Zeocin or nourseothricin were not resistant against blasticidin-S. In a proof of concept, we also successfully generated double resistant (against blasticidin-S and nourseothricin) P. tricornutum cell lines by co-delivering the bsr vector with a vector conferring nourseothricin resistance to wild-type cells

Localization of heme biosynthesis in the diatom Phaeodactylum tricornutum and differential expression of multi-copy enzymes

Heme is essential for all organisms. The composition and location of the pathway for heme biosynthesis, have been influenced by past endosymbiotic events and organelle evolution in eukaryotes. Endosymbioses led to temporary redundancy of the enzymes and the genes involved. Genes were transferred to the nucleus from different endosymbiotic partners, and their multiple copies were either lost or retained, resulting in a mosaic pathway. This mosaic is particularly complex in organisms with eukaryote-derived plastids, such as diatoms. The plastids of diatoms are clearly derived from red algae. However, it is not entirely clear whether they were acquired directly from a red algal ancestor or indirectly in higher-order endosymbioses. In the diatom Phaeodactylum tricornutum, most enzymes of the pathway are present in a single copy, but three, glutamyl-tRNA synthetase (GluRS), uroporphyrinogen decarboxylase (UROD) and coproporphyrinogen oxidase (CPOX), are encoded in multiple copies. These are not direct paralogs resulting from gene duplication within the lineage but were acquired horizontally during the plastid endosymbioses. While some iso-enzymes originate from the host cell, others originate either from the genome of the cyanobacterial ancestor of all plastids or from the nuclear genome of the eukaryotic ancestor of the diatom complex plastid, a rhodophyte or an alga containing rhodophyte-derived plastids, a situation known as pseudoparalogy. Using green fluorescent protein-tagged expression and immunogold labeling, we experimentally localized all enzymes of the pathway in P. tricornutum, and confirmed their localization in the plastid, with a few possible exceptions. Our meta-analyses of transcription data showed that the pseudoparalogs are differentially expressed in response to nitrate starvation, blue light, high light, high CO2, and the cell cycle. Taken together, our findings emphasize that the evolution of complex plastids via endosymbiosis has a direct impact not only on the genetics but also on the physiology of resulting organisms

Evolutionary genomics of a cold-adapted diatom: Fragilariopsis cylindrus

The Southern Ocean houses a diverse and productive community of organisms1, 2. Unicellular eukaryotic diatoms are the main primary producers in this environment, where photosynthesis is limited by low concentrations of dissolved iron and large seasonal fluctuations in light, temperature and the extent of sea ice3, 4, 5, 6, 7. How diatoms have adapted to this extreme environment is largely unknown. Here we present insights into the genome evolution of a cold-adapted diatom from the Southern Ocean, Fragilariopsis cylindrus8, 9, based on a comparison with temperate diatoms. We find that approximately 24.7 per cent of the diploid F. cylindrus genome consists of genetic loci with alleles that are highly divergent (15.1 megabases of the total genome size of 61.1 megabases). These divergent alleles were differentially expressed across environmental conditions, including darkness, low iron, freezing, elevated temperature and increased CO2. Alleles with the largest ratio of non-synonymous to synonymous nucleotide substitutions also show the most pronounced condition-dependent expression, suggesting a correlation between diversifying selection and allelic differentiation. Divergent alleles may be involved in adaptation to environmental fluctuations in the Southern Ocean

Using diatom and apicomplexan models to study the heme pathway of Chromera velia

Heme biosynthesis is essential for almost all living organisms. Despite its conserved function, the pathway’s enzymes can be located in a remarkable diversity of cellular compartments in different organisms. This location does not always reflect their evolutionary origins, as might be expected from the history of their acquisition through endosymbiosis. Instead, the final subcellular localization of the enzyme reflects multiple factors, including evolutionary origin, demand for the product, availability of the substrate, and mechanism of pathway regulation. The biosynthesis of heme in the apicomonad Chromera velia follows a chimeric pathway combining heme elements from the ancient algal symbiont and the host. Computational analyses using different algorithms predict complex targeting patterns, placing enzymes in the mitochondrion, plastid, endoplasmic reticulum, or the cytoplasm. We employed heterologous reporter gene expression in the apicomplexan parasite Toxoplasma gondii and the diatom Phaeodactylum tricornutum to experimentally test these predictions. 5-aminolevulinate synthase was located in the mitochondria in both transfection systems. In T. gondii, the two 5-aminolevulinate dehydratases were located in the cytosol, uroporphyrinogen synthase in the mitochondrion, and the two ferrochelatases in the plastid. In P. tricornutum, all remaining enzymes, from ALA-dehydratase to ferrochelatase, were placed either in the endoplasmic reticulum or in the periplastidial space

Gesellschaftlicher Aufbruch, reale Utopien und die Arbeit am Sozialen

People around the world recollect socially responsible and desirable values, new forms of living and coexistence as well as eco-social economic activities. This volume is dedicated to these real utopias –positive ideas aiming at a better future and practical approaches combining notions of a more livable society with concrete practical implementations.Weltweit besinnen sich Menschen auf gesellschaftlich Verantwortbares und Wünschenswertes, auf neue Formen des Lebens und Zusammenlebens und des ökosozialen Wirtschaftens. Dieser Band widmet sich diesen realen Utopien, positiven, in eine bessere Zukunft gerichteten Vorstellungen und praktischen Ansätzen, die Ideen von einer lebenswerteren Gesellschaft mit konkreter Praxis verbinden

Do Hospitals Respond to Increasing Prices by Supplying Fewer Services?

Medical providers often have a significant influence on treatment decisions which they can use in their own financial interest. Classical models of supplier-induced demand predict that medical providers will supply fewer services if they face increasing prices. We test this prediction based on a reform of hospital financing in Germany. Uniquely, this reform changed the overall level of reimbursement - with increasing prices for some hospitals and decreasing prices for others - without affecting the relative prices for different types of patients. Based on administrative data, we find that hospitals do indeed react to increasing prices by reducing service supply.Anbieter von medizinischen Leistungen treffen häufig Behandlungsentscheidungen für ihre Patienten und haben die Möglichkeit, bei diesen Entscheidungen ihre eigenen finanziellen Interessen zu berücksichtigen. Klassische Modelle der Theorie der 'angebotsinduzierten Nachfrage' prognostizieren, dass medizinische Anbieter auf höhere Preise reagieren, indem sie weniger Leistungen erbringen. Wir testen diese Vorhersage auf Grundlage einer Reform der Krankenhausfinanzierung in Deutschland. Das Besondere an der Finanzierungsreform in Deutschland ist, dass die Reform die Preise für Krankenhäuser verändert hat - mit steigenden Preisen für einige Krankenhäuser und sinkenden Preisen für andere - ohne dabei die relativen Preise für die Behandlung unterschiedlicher Patientengruppen oder unterschiedlicher Krankheiten zu beeinflussen. Unter Nutzung administrativer Daten finden wir, dass Krankenhäuser tatsächlich weniger Leistungen erbringen, wenn die Preise steigen

Current Account Imbalances in the Euro Area: Catching Up or Competitiveness?

In the debate on global imbalances, the euro area countries did not receive much attention so far. While the current account is on balance for the entire area, divergences between individual member states have increased since the introduction of the common currency. In this paper, the imbalances are traced back to catching up and competitiveness factors using paneleconometric techniques. In line with the intertemporal approach to the current account, low income countries tend to run deficits, while rich countries realize surpluses. However, the effect diminishes, if early years are dropped from the sample. The competitiveness channel is more robust and shows the expected sign, i.e. a real appreciation leads to external deficits. To restore competitiveness, a reduction of unit labour costs is on the agenda. Since a deterioration of competitiveness is not a feasible strategy for the surplus countries, an asymmetric response across countries is required in order to reduce the imbalances.In der Diskussion über globale Ungleichgewichte spielen die Länder der Eurozone bisher nicht die zentrale Rolle. Während die Leistungsbilanz für die gesamte Währungsunion ausgeglichen ist, sind die Ungleichgewichte zwischen den Mitgliedsländern erheblich und haben sich seit der Einführung der gemeinsamen Währung erhöht. In diesem Papier werden die Ungleichgewichte auf ökonomische Aufholprozesse und Wettbewerbsfähigkeit zurückgeführt. Dabei kommen panelökonometrische Methoden zum Einsatz. Bei Wohlfahrtunterschieden sollten Länder mit niedrigen Einkommen Defiziten, reichen Länder hingegen Überschüsse realisieren. Dieser Effekt nimmt jedoch im Zeitablauf ab. Eeine Erklärung über die Wettbewerbsfähigkeit ist robuster und zeigt die erwarteten VorZeichen, d.h. eine reale Aufwertung führt zu externen Defizite. Zur Wiederherstellung der Wettbewerbsfähigkeit steht eine Reduzierung der Lohnstückkosten steht auf der Tagesordnung. Da eine Verschlechterung der Wettbewerbsfähigkeit keine geeignete Strategie für die Überschussländer ist, scheint eine asymmetrische Reaktion in den einzelnen Ländern erforderlich zu sein, um die Ungleichgewichte in der Währungsunion zu verringern