Novel strategies of maintaining and transmitting specific microbial symbionts in marine flatworms

Tiere mit intrazellulären mikrobiellen Symbionten kommen in zahlreichen Lebensräumen vor. In den bekannten Fällen profitieren die Wirtstiere von den umfangreichen metabolischen Fähigkeiten der Symbionten, die es ihnen ermöglichen, zusätzliche Nahrungs- und Energiequellen zu nutzen. Eine besondere Herausforderung in der Erforschung von Tier-Mikroben Symbiosen ist die Identifikation der Mechanismen, die es dem Wirt erlauben (1) spezifische Partnerschaften mit Symbionten in speziellen Wirtszellen – den Bakteriozyten – einzugehen und aufrecht zu halten, sowie (2) diese intrazellulären Symbionten während der Fortpflanzung an die Nachkommenschaft weiterzugeben (Transmission). Bislang war die Erforschung der de novo Formation von Bakteriozyten (die Differenzierung der Wirtszelle inklusive der Aufnahme von Symbionten) dadurch limitiert, dass dieser Prozess in den verfügbaren Modellsystemen auf frühe, temporäre Entwicklungsstadien begrenzt ist. In Bezug auf die Transmission von Symbionten sind zwei grundlegende Strategien bekannt: horizontale Transmission (Symbionten werden von jeder Wirtsgeneration neu aus der Umwelt aufgenommen) oder vertikale Transmission (Symbionten werden von den Eltern direkt an den Nachwuchs weitergegeben). Strikt-vertikale Transmission ist in der Regel verbunden mit Kodiversifikation der Partner (kongruente Topologie der Stammbäume von Wirt und Symbiont). Das zentrale Forschungsobjekt dieser Arbeit waren mund- und darmlose marine Platyhelminthen der Gattung Paracatenula und deren bakterielle Symbionten, die eingebettet in Bakteriozyten den Großteil des Tierkörpers füllen. Im Speziellen wurde untersucht, wie diese Tiere ihre Symbiose während Wachstum und Entwicklung aufrecht halten und die Symbionten bei der Fortpflanzung an die Nachkommenschaft weitergeben werden. Die im Folgenden zusammengefassten Ergebnisse zu diesen Fragestellungen erlauben ein sehr viel besseres Verständnis der Paracatenula Symbiose und ermöglichen zusätzlich interessante Rückschlüsse auf andere symbiotische Beziehungen bis hin zur Evolution der eukaryotischen Zellorganellen. Der erste Teil dieser Doktorarbeit ist die Beschreibung einer neu entdeckten Paracatenula Art, Paracatenula galateia, die sich als äußerst gut geeignet für weitere in dieser Studie durchgeführte Experimente herausstellte. P. galateia konnte zuverlässig im Freiland gesammelt und sogar für einige Wochen kultiviert und inkubiert werden. Dies ist bislang mit keiner anderen Paracatenula Art gelungen. Weiterhin zeigte sich eine vergleichsweise gute Handhabbarkeit der Tiere bei der Anwendung verschiedener Färbe- und Markierungstechniken. Eine wichtige Erkenntnis ergab sich durch die phylogenetische Analyse von mehreren Paracatenula-Arten und deren Symbionten. Diese zeigte nicht nur, dass in den Bakteriozyten der Würmer die ersten bekannten thiotrophen alphaproteobacteriellen Symbionten leben, sondern es spiegelt sich auch eine strikte, seit mehreren hundert Millionen Jahren andauernde Koevulotion von Wirt und Symbiont wieder. Durch Markierungsexperimente mit Thymidin-Analoga (BrdU und EdU) konnten S-Phase Zellen in P. galateia identifiziert und deren Schicksale verfolgt werden. Dabei zeigte sich, dass offenbar alle Zellen in den Tieren ausschließlich von so genannten Neoblasten (kontinuierlich proliferierende pluripotente Stammzellen in Platyhelminthen) abstammen. Im speziellen konnte dann dokumentiert werden, dass erst mehrere Tage nach dem S-Phase Markierungspuls ein Signal in den Bakteriozyten und vielen anderen differenzierten Zelltypen nachweisbar ist. Diese Verzögerung rührt daher, dass die Tochterzellen der Neoblasten Zeit benötigen um im Körper des Tieres zu ihrer Zielposition zu wandern und zu differenzieren. Die kontinuierliche de novo Bildung von Bakteriozyten ist einzigartig unter den bekannten Symbiosen und macht P. galateia zu einem vielversprechenden Modellsystem um den Entwicklungsprozess dieses besonderen Zelltyps im Detail zu erforschen. Als erstaunlich erwies sich auch die Symbionten-Transmissions-Strategie der Tiere. P. galateia vermehrt sich hauptsächlich (vielleicht ausschließlich) asexuell durch Paratomie (transversale Teilung, bei der die Differenzierung neuer, zu ersetzender Organe vor der Trennung vom Elterntier eingeleitet wird) oder durch die Regeneration versehentlich abgerissener Fragmente. Mit diesen Fragmenten übertragen die Wirte große Mengen an Symbionten. Diese Art der vertikalen Transmission unterscheidet sich besonders dadurch von allen anderen beschriebenen, dass die Symbionten völlig unbehelligt in ihren gewohnten Lebensraum, dem inneren der Bakteriozyten, verbleiben. In allen anderen untersuchten Symbiosen mit Bakteriozyten müssen die Symbionten, selbst wenn die Transmission vertikal erfolgt, von der elterlichen Bakteriozyte in eine Keimzelle oder direkt zur Nachkommenschaft wechseln. Dabei kommt es immer wieder zum Kontaktverlust der Partner und gegebenenfalls zum Symbionten-Wechsel im Falle dass andere Mikroben, die nicht direkt von den Eltern kommen, aufgenommen werden. Weiterhin birgt die Weitergabe geringer Symbionten-Mengen aus einer kleinen, abgeschlossenen Population das Risiko der Akkumulation schädlicher Mutationen in diese Population. Dies wird als „Transmissions-Flaschenhals“ bezeichnet. Im Falle von P. galateia kommen all diese Transmissionsrisiken nicht zum Tragen, da zahlreiche Symbionten im Inneren der Bakteriozyten direkt an die asexuelle Nachkommenschaft weitergegeben werden. Diese besondere Art der Transmission könnte die strikte Kodiversifikation von Paracatenula Wirten mit ihren jeweiligen Symbionten erklären. Beides, die wiederholte de novo Bildung der Bakteriozyten und deren Transmission an die asexuellen Nachkommen in P. galateia reflektieren den hohen Grad an Symbionten-Integration in das Entwicklungsprogramm des Wirtes. Die weitere Erforschung dieser besonders engen Partnerschaft verspricht nicht nur ein besseres Verständnis von der Interaktion zwischen Tier und Bakterie, sondern könnte auch neue Erkenntnisse über die Evolution von Zellorganellen eröffnen.Animals engaged in obligate intracellular symbiosis with microbes occur in a wide range of habitats. In the known cases the animal hosts profit from the metabolic capabilities of their symbionts which enable them to utilize additional food and energy resources. A major challenge in animal-microbe symbiosis research is to identify the mechanisms which allow hosts (1) to selectively establish and maintain associations with microbial symbionts inside specific host cells – the bacteriocytes - and (2) to pass these symbionts to the offspring during reproduction (transmission). To date, the investigation of bacteriocyte de novo formation (host cell differentiation and uptake of symbionts) was limited by the fact that this process is restricted to early, temporary developmental stages in the available animal model systems. Related to symbiont transmission two principal modes are known: horizontal transmission (each host generation takes up the symbionts anew from the environment) and vertical transmission (the parents transfer the symbionts directly to the offspring). Strict vertical transmission is usually connected with codiversification of the partners (congruent topology of the phylogenetic trees from host and symbiont). The central objects of research in this thesis were mouth- and gutless marine Platyhelminthes of the genus Paracatenula and their bacterial symbionts. The latter are embedded in bacteriocytes that fill up large parts of the worm´s body. In particular it was analyzed how these animals maintain their symbiosis during growth and development and how they transmit the symbionts to the offspring during reproduction. The results summarized hereafter allow a considerably better understanding of the Paracatenula symbiosis. In addition they contribute to the understanding of other symbiotic associations possibly right up to the evolution of eukaryotic cell organelles. The first part of this thesis is the description of a newly discovered Paracatenula-species, Paracatenula galateia, which appeared to be well suited for further experiments that were conducted for this thesis. P. galateia could be sampled reliably in the field and even cultivated for up to several weeks, which was not possible with any other Paracatenula-species so far. In addition it appeared to be comparatively easy to handle during different staining and labeling procedures. An important insight resulted from the phylogenetic analysis of numerous Paracatenula-species and their symbionts. It did not only identify the symbionts as the first known thiotrophic alphaproteobacterial symbionts, it furthermore revealed that hosts and symbionts coevolve since hundreds of million years. We identified S-phase cells in P. galateia by applying pulse-labeling experiments with the thymidine-analogues BrdU and EdU and we traced their fates in pulse-chase experiments. The experiments revealed that apparently all cells in the animals exclusively derive from so called neoblasts (continuously proliferating pluripotent stem cells of Plathyhelminthes). It was documented in particular, that the S-phase label appears in bacteriocytes and many other differentiated cell types several days after the pulse-labeling. This delay is due to the time which neoblast daughter cells need to migrate and differentiate. The continued de novo formation of bacteriocytes in P. galateia is unique among all symbiosis models and makes this worm a promising model system to study the developmental detail of this exceptional cell type. Astonishing was also the strategy of symbiont transmission observed in the animals. P. galateia reproduce predominantly asexually by paratomy (transverse fission during which differentiation of new organs occurs prior to separation from the parental animal; see introduction) and regeneration of accidently torn off fragments. Inside these fragments the host transmits numerous symbionts vertically. This kind of transmission is different from the described ones, since the symbionts permanently remain in their familiar environment, the bacteriocytes. In all other known cases of bacteriocyte possessing animals, the symbionts must translocate from the parental bacteriocyte to either a germ cell or directly to the offspring. This translocation bears the risk of detachment for the partners and may also result in host-switching in case other microbes, which do not directly come from the parent, are taken up by the offspring. Furthermore the transmission of low numbers of symbionts deriving from a small enclosed population can lead to an accumulation of deleterious mutations in this population. This effect is termed “transmission bottleneck”. In case of P. galateia all these transmission-risks do not come into effect since numerous symbionts inside of bacteriocytes are transmitted to the asexual offspring. This exceptional transmission strategy may explain the strict codiversification of Paracatenula hosts and their respective symbionts. Both, the de novo formation of bacteriocytes and their transmission to the asexual offspring reflect a high degree of symbiont integration into the developmental programs of the Paracatenula-host. A further investigation of this especially-tight obligate mutualistic partnership promises not only a better understanding of the interaction between animal and microbe, but it could also open up new insights of eukaryotic cell organelle evolution

Astrophysikalische Staubbildung unter fluktuierenden Temperaturbedingungen

Nukleation und Wachstum von Staub ist astrophysikalisch insbesondere in den stellaren Winden von kühlen Riesen und Überriesen anzutreffen. In den vorliegenden Modellen für die circumstellaren Staubhüllen von AGB-Sternen bleibt bislang der Umstand weitgehend unberücksichtigt, daß Sternatmosphären turbulente physikalische Systeme sind. Ziel der Arbeit ist es daher, die Effekte von irregulären Schwankungen der Temperatur, die entscheidenden Einfluß auf die Vorgänge bei Staubbildung und Staubwachstum / -verdampfung hat, prototypartig zu untersuchen. Die für eine statistische Beschreibung der Staubbildung unter dem Einfluß solcher Temperaturfluktuationen verfolgte mathematische Zugangsweise einer Formulierung der Physik in stochastischen Prozessen soll dabei gleichzeitig die Verbindung leisten zwischen der physikalischen Problemsituation, für die keine befriedigende Turbulenztheorie vorliegt, und den in der Mathematik vorhandenen leistungsfähigen stochastischen Methoden. Unter der Annahme der Markov-Eigenschaft des betrachteten stochastischen Prozesses läßt sich ein System von Fokker-Planck-Gleichungen herleiten, als dessen Lösung sich die Wahrscheinlichkeit ergibt, zu einem gegebenen Zeitpunkt bestimmte Werte der Temperatur und der Staubbildung anzutreffen. Für eine konkrete Formulierung dieses Gleichungssystems wird die Übergangswahrscheinlichkeit des Markov-Prozesses physikalisch begründet angesetzt. Unter der Annahme einer Separierbarkeit der Übergangswahrscheinlichkeit aufgrund des Vernachlässigens der Rückwirkung der Staubbildung auf die Ursachen der Fluktuationen wird einerseits die Temperaturkomponente durch Lösung einer die Fluktuation statistisch beschreibenden stochastischen Differentialgleichung als Ornstein-Uhlenbeck-Prozeß bestimmt; andererseits ergibt sich die Prozeßkomponente der Staubentwicklung mithilfe des deterministischen Systems der Momentengleichungen (Gail, Sedlmayr) für Staubbildung. Bei geeigneten Anfangs- und Randbedingungen wird das Problem bei Vorgabe von Windmodellen einer numerischen Behandlung zugeführt. Die Lösungen liefern für die Erwartungswerte als Ergebnis neben detaillierten Abhängigkeiten von den unterschiedlichen Parametern insbesondere: (a) Bedingt durch die Temperaturfluktuationen setzt die effektive Bildung von Staub deutlich früher, 'turbulenzgetrieben' im stellaren Wind ein. (b) Der Bereich der Sternatmosphäre, innerhalb dessen sich Staubbildung und -wachstum vollziehen, ist bei zunehmender Fluktuation deutlich ausgedehnter als im nicht-stochastischen Fall. Innerhalb dieser 'fluktuations-geprägten' Zone hängt der Verlauf der Lösungen von der Größe der Temperaturstandardabweichung ebenso ab wie von der Korrelationslänge; insbesondere entstehen rasch große Körner, deren weiteres Wachstum dann von den spezifischen Turbulenzbedingungen abhängt. (c) Während der makroturbulente Grenzfall in ein quasideterministisches Verhalten übergeht, prägen sich im Falle der Mikroturbulenz die charakteristischen Fluktuationseffekte in Abhängigkeit von der Temperaturstreuung voll aus. Aufgrund dieser Effekte ist es für zukünftige Forschungsschritt

Evidence for a large off-centered galactic outflow and its connection to the extraplanar diffuse ionized gas in IC 1553

Aims. We analyze a MUSE optical integral field spectrum of the star-forming edge-on galaxy IC 1553 in order to study its extraplanar diffuse ionized gas (eDIG) and the processes shaping its disk-halo interface. Methods. We extracted the optical emission line properties from the integral field spectrum and generated the commonly used emission line diagnostic diagrams in order to analyze the ionization conditions and the distribution of the eDIG. Furthermore, we performed gravitational potential fitting to investigate the kinematics of a suspected galactic outflow. Results. We find that the eDIG scale height has a maximum value of approximately 1.0 kpc and decreases roughly linearly with the radial distance from the galactic center in projection. The ionization state of the eDIG is not consistent with a pure photoionization scenario and instead requires a significant contribution from shock ionization. This, in addition to the gas kinematics, strongly suggests the presence of a galactic scale outflow, the origin of which lies at least 1.4 kpc away from the galactic center. The inferred shock velocity in the eDIG of approximately 225 km s-1 is comparable to the escape velocity estimated from our potential modelling. The asymmetric distribution of currently star-forming clusters produces a range of different ionization conditions in the eDIG. As a result, the vertical emission line profiles vary quantitatively and qualitatively along the major axis of the galaxy. This analysis illustrates that it is crucial in studies of the eDIG to use observations that take the spatial and kinematical distributions into account, such as those done with integral field units, to form an accurate picture of the relevant physical properties.Comment: Accepted for publication by Astronomy & Astrophysics on August 1, 202

Outcome of acute respiratory distress syndrome in university and non- university hospitals in Germany

Background This study investigates differences in treatment and outcome of ventilated patients with acute respiratory distress syndrome (ARDS) between university and non-university hospitals in Germany. Methods This subanalysis of a prospective, observational cohort study was performed to identify independent risk factors for mortality by examining: baseline factors, ventilator settings (e.g., driving pressure), complications, and care settings—for example, case volume of ventilated patients, size/type of intensive care unit (ICU), and type of hospital (university/non-university hospital). To control for potentially confounding factors at ARDS onset and to verify differences in mortality, ARDS patients in university vs non-university hospitals were compared using additional multivariable analysis. Results Of the 7540 patients admitted to 95 ICUs from 18 university and 62 non-university hospitals in May 2004, 1028 received mechanical ventilation and 198 developed ARDS. Although the characteristics of ARDS patients were very similar, hospital mortality was considerably lower in university compared with non- university hospitals (39.3% vs 57.5%; p = 0.012). Treatment in non-university hospitals was independently associated with increased mortality (OR (95% CI): 2.89 (1.31–6.38); p = 0.008). This was confirmed by additional independent comparisons between the two patient groups when controlling for confounding factors at ARDS onset. Higher driving pressures (OR 1.10; 1 cmH2O increments) were also independently associated with higher mortality. Compared with non- university hospitals, higher positive end-expiratory pressure (PEEP) (mean ± SD: 11.7 ± 4.7 vs 9.7 ± 3.7 cmH2O; p = 0.005) and lower driving pressures (15.1 ± 4.4 vs 17.0 ± 5.0 cmH2O; p = 0.02) were applied during therapeutic ventilation in university hospitals, and ventilation lasted twice as long (median (IQR): 16 (9–29) vs 8 (3–16) days; p < 0.001). Conclusions Mortality risk of ARDS patients was considerably higher in non-university compared with university hospitals. Differences in ventilatory care between hospitals might explain this finding and may at least partially imply regionalization of care and the export of ventilatory strategies to non-university hospitals

Microanatomy of the trophosome region of Paracatenula cf. polyhymnia (Catenulida, Platyhelminthes) and its intracellular symbionts

Marine catenulid platyhelminths of the genus Paracatenula lack mouth, pharynx and gut. They live in a symbiosis with intracellular bacteria which are restricted to the body region posterior to the brain. The symbiont-housing cells (bacteriocytes) collectively form the trophosome tissue, which functionally replaces the digestive tract. It constitutes the largest part of the body and is the most important synapomorphy of this group. While some other features of the Paracatenula anatomy have already been analyzed, an in-depth analysis of the trophosome region was missing. Here, we identify and characterize the composition of the trophosome and its surrounding tissue by analyzing series of ultra-thin cross-sections of the species Paracatenula cf. polyhymnia. For the first time, a protonephridium is detected in a Paracatenula species, but it is morphologically reduced and most likely not functional. Cells containing needle-like inclusions in the reference species Paracatenula polyhymnia Sterrer and Rieger, 1974 were thought to be sperm, and the inclusions interpreted as the sperm nucleus. Our analysis of similar cells and their inclusions by EDX and Raman microspectroscopy documents an inorganic spicule consisting of a unique magnesium–phosphate compound. Furthermore, we identify the neoblast stem cells located underneath the epidermis. Except for the modifications due to the symbiotic lifestyle and the enigmatic spicule cells, the organization of Paracatenula cf. polyhymnia conforms to that of the Catenulida in all studied aspects. Therefore, this species represents an excellent model system for further studies of host adaptation to an obligate symbiotic lifestyle

Whole-Blood Flow-Cytometric Analysis of Antigen-Specific CD4 T-Cell Cytokine Profiles Distinguishes Active Tuberculosis from Non-Active States

T-cell based IFN-γ release assays do not permit distinction of active tuberculosis (TB) from successfully treated disease or latent M. tuberculosis infection. We postulated that IFN-γ and IL-2 cytokine profiles of antigen-specific T cells measured by flow-cytometry ex vivo might correlate with TB disease activity in vivo. Tuberculin (PPD), ESAT-6 and CFP-10 were used as stimuli to determine antigen-specific cytokine profiles in CD4 T cells from 24 patients with active TB and 28 patients with successfully treated TB using flow-cytometry. Moreover, 25 individuals with immunity consistent with latent M. tuberculosis infection and BCG-vaccination, respectively, were recruited. Although the frequency of cytokine secreting PPD reactive CD4 T cells was higher in patients with active TB compared to patients with treated TB (median 0.81% vs. 0.39% of CD4 T cells, p = 0.02), the overlap in frequencies precluded distinction between the groups on an individual basis. When assessing cytokine profiles, PPD specific CD4 T cells secreting both IFN-γ and IL-2 predominated in treated TB, latent infection and BCG-vaccination, whilst in active TB the cytokine profile was shifted towards cells secreting IFN-γ only (p<0.0001). Cytokine profiles of ESAT-6 or CFP-10 reactive CD4 T cells did not differ between the groups. Receiver operator characteristics (ROC) analysis revealed that frequencies of PPD specific IFN-γ/IL-2 dual-positive T cells below 56% were an accurate marker for active TB (specificity 100%, sensitivity 70%) enabling effective discrimination from non-active states. In conclusion, a frequency lower than 56% IFN-γ/IL-2 dual positive PPD-specific circulating CD4 T-cells is strongly indicative of active TB

Highly Asynchronous and Asymmetric Cleavage Divisions Accompany Early Transcriptional Activity in Pre-Blastula Medaka Embryos

In the initial phase of development of fish embryos, a prominent and critical event is the midblastula transition (MBT). Before MBT cell cycle is rapid, highly synchronous and zygotic gene transcription is turned off. Only during MBT the cell cycle desynchronizes and transcription is activated. Multiple mechanisms, primarily the nucleocytoplasmic ratio, are supposed to control MBT activation. Unexpectedly, we find in the small teleost fish medaka (Oryzias latipes) that at very early stages, well before midblastula, cell division becomes asynchronous and cell volumes diverge. Furthermore, zygotic transcription is extensively activated already after the 64-cell stage. Thus, at least in medaka, the transition from maternal to zygotic transcription is uncoupled from the midblastula stage and not solely controlled by the nucleocytoplasmic ratio

Bacterial Symbiosis Maintenance in the Asexually Reproducing and Regenerating Flatworm Paracatenula galateia

Bacteriocytes set the stage for some of the most intimate interactions between animal and bacterial cells. In all bacteriocyte possessing systems studied so far, de novo formation of bacteriocytes occurs only once in the host development, at the time of symbiosis establishment. Here, we present the free-living symbiotic flatworm Paracatenula galateia and its intracellular, sulfur-oxidizing bacteria as a system with previously undescribed strategies of bacteriocyte formation and bacterial symbiont transmission. Using thymidine analogue S-phase labeling and immunohistochemistry, we show that all somatic cells in adult worms – including bacteriocytes – originate exclusively from aposymbiotic stem cells (neoblasts). The continued bacteriocyte formation from aposymbiotic stem cells in adult animals represents a previously undescribed strategy of symbiosis maintenance and makes P. galateia a unique system to study bacteriocyte differentiation and development. We also provide morphological and immunohistochemical evidence that P. galateia reproduces by asexual fragmentation and regeneration (paratomy) and, thereby, vertically transmits numerous symbiont-containing bacteriocytes to its asexual progeny. Our data support the earlier reported hypothesis that the symbiont population is subjected to reduced bottleneck effects. This would justify both the codiversification between Paracatenula hosts and their Candidatus Riegeria symbionts, and the slow evolutionary rates observed for several symbiont genes

Conversion to Islam as a Strategy of Change and Differentiation in Modernity

ABSTRACT: This article seeks to contribute to the knowledge of Islam in the Colombian context, through ethnographic observations and narratives of individuals who have converted to said religion in Bogota. In addition to analyzing the motives for their conversion, it studies the way these people have constructed a new religious identity altering their perception of themselves, their system of beliefs and values, their behavior and their relation to the socio-cultural environment around them. It also examines the link between the private and the public spheres, between the symbolic and the political, that becomes visible when, by openly adhering to a religion that is usually stigmatized, a person resists the hegemonic forms of socialization in Colombian society.RESUMEN: Este artículo busca aportar al conocimiento del islam en el contexto colombiano a partir de observaciones etnográficas y narrativas de sujetos que se han convertido a esta religión en Bogotá. Además de analizar las motivaciones de sus conversiones, estudiamos la forma en que las personas han construido una nueva identidad religiosa alterando su percepción de sí mismas, su sistema de creencias y valores, su comportamiento y su relación con el medio sociocultural que las rodea. Se examina también el enlace entre lo privado y lo público, entre lo simbólico y lo político, que se hace visible cuando, al adherir abiertamente a una religión usualmente estigmatizada, la persona resiste frente a formas de socialización hegemónicas de la sociedad colombiana

TERT promoter mutations are highly recurrent in SHH subgroup medulloblastoma

Telomerase reverse transcriptase (TERT) promoter mutations were recently shown to drive telomerase activity in various cancer types, including medulloblastoma. However, the clinical and biological implications of TERT mutations in medulloblastoma have not been described. Hence, we sought to describe these mutations and their impact in a subgroup-specific manner. We analyzed the TERT promoter by direct sequencing and genotyping in 466 medulloblastomas. The mutational distributions were determined according to subgroup affiliation, demographics, and clinical, prognostic, and molecular features. Integrated genomics approaches were used to identify specific somatic copy number alterations in TERT promoter-mutated and wild-type tumors. Overall, TERT promoter mutations were identified in 21 % of medulloblastomas. Strikingly, the highest frequencies of TERT mutations were observed in SHH (83 %; 55/66) and WNT (31 %; 4/13) medulloblastomas derived from adult patients. Group 3 and Group 4 harbored this alteration in <5 % of cases and showed no association wit