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FS MARIA S. MERIAN Expedition MSM06 umfasst drei Fahrtabschnitte, die zum Ziel haben den Hydrothermalismus sowie Tiefwasser-Ökosysteme im Atlantik zu untersuchen. Der erste Fahrtabschnitt konzentriert sich auf die Untersuchung von Kaltwasserkorallen-Ökosystemen im Golf von Cádiz. Das Hauptziel ist die Identifizierung der für die Korallenverteilung verantwortlichen Kontrollfaktoren. Zudem soll untersucht werden, wie sich die Korallenökosysteme in der Vergangenheit unter sich verändernden Umweltbedingungen entwickelt haben. Der zweite Fahrtabschnitt führt zum Logatchev-Hydrothermalfeld am Mittelatlantischen Rücken im westlichen N-Atlantik. Es ist geplant eine örtlich fokussierte Studie durchzuführen, um die Ursachen für zeitliche und örtliche Unterschiede in der Zusammensetzung von hydrothermalen Fluiden sowie deren Auswirkungen auf Vent-Lebensgemeinschaften zu erforschen. Fahrtabschnitt 3 führt zu einem weiter östlich, direkt südlich des Äquators, gelegenen Bereich des Mittelatlantischen Rückens. Hier soll der Einfluss großmaßstäblicher magmatischer und tektonischer Prozesse an Hydrothermalsystemen in vier verschiedenen Vent-Feldern untersucht werden. Um die genannten Detail-Untersuchungen in den einzelnen Untersuchungsgebieten durchführen zu können, ist v.a. der Einsatz eines ferngesteuerten Tauchroboters (ROV) auf allen 3 Fahrtabschnitten von besonderer Bedeutung. Dies unterstreicht, wie neue Technologien, wissenschaftliche Arbeiten zu einem bis dato unerreichten Niveau der Detailgenauigkeit verhelfen.
Fahrtabschnitt MSM 03/1: Der nördliche Atlantik weist drei Eigenschaften auf, die ihn zu einem der interessantesten Meeresgebiete machen. Zum einen beginnt hier das Absinken von kalten und dichten Wassermassen nördlich von Grönland und Island und bildet dadurch einen wichtigen Faktor der globalen ozeanischen Wasserzirkulation, dem globalen Strömungsgürtel. Zum anderen transportiert die Verlängerung des Golf Stromes, die Nordatlantische Drift, warmes Oberflächenwasser bis nach Spitzbergen und beeinflußt so entscheidend das Klima in Europa. Schließlich fließen kalte Oberflächenwässer an der Küste Grönlands entlang südwärts und transportieren nährstoffreiches Wasser in den Süden. Während der letzten 15 Jahre ist mit Hilfe von kultivierungsunabhängigen Methoden die mikrobiellen Gemeinschaften in verschiedenen marinen Systemen sehr intensiv erforscht worden. Viele unbekannte und nicht kultivierte Organismen wie der weit verbreitete SAR11 Cluster wurden entdeckt und quantitativ verfolgt. Kürzlich wurden Genomanalysen ganzer mikrobieller Gemeinschaften initiiert (Metagenomics). Jedoch bleibt solche Forschung oft auf küstennahe Standorte beschränkt. Nur wenige Studien beschrieben bisher die mikrobielle Diversität, Struktur und Funktion im offenen Ozean und über ganze Meeresbecken hinweg. Das sogenannte AMT (Atlantic Meridional Transect) Programm ist eines dieser Studien, welche es sich zur Aufgabe gemacht hat, den gesamten Atlantischen Ozean von den britischen Inseln (50°N) bis zu den Falkland Inseln (50°S) zu untersuchen. Zweimal im Jahr werden in einem interdisziplinären Ansatz der Einfluß der biotischen (Phytoplankton, Zooplankton, Mikrobiologie) und abiotischen Faktoren (physikalischen und chemischen Parameter) auf die gesamte mikrobielle Gemeinschaft untersucht. Erste Ergebnisse dieser Studien bestätigten zum Beispiel die Einnischung von verschiedenen Ökotypen des wichtigen Primärproduzenten Prochlorococcus in distinkte Wasserkörper (Tiefe, Breitengrad) entlang des Atlantischen Ozeans. Eine erste Studie zur Erforschung des Picoplanktons nördlich des 50° Breitengrades stellte das PRIME Programm dar. Neuere Untersuchungen in dem Gebiet richteten sich auf die Bakterioplankton-Gemeinschaft von Tiefenwässern unterhalb von 1000 m. Für die Oberflächengewässer dieser Region jedoch fehlt eine genauere Untersuchung der Diversität, Struktur und Funktion der mikrobiellen Gemeinschaft mit modernen molekularbiologischen Methoden. Fahrtabschnitt MSM 03/2: Das Ziel der Forschungsfahrt ist die detaillierte Untersuchung des flachen Untergrundes im Logatchev Hydrothermalfeldam Mittelatlantischen Rücken (MAR) bei 15°N mit bis zu 15 m tiefen Bohrungen. Die Fahrt findet im Rahmen des DFG-SPP 1144 statt und komplettiert die bisher gewonnenen Oberflächenproben sowie die im Rahmen des ODP-Leg 209 gewonnenen Tiefen-proben. Das in 3000m Wassertiefe liegende und an Mantelgesteine gebundene Logatchev Hydrothermalfeld ist durch intensive Anreicherung an Kupfer, Gold, Kobalt und anderen Wertelementen am Meersboden und vermutlich auch im flachen Untergrund gekennzeichnet. Gleichzeitig sind die hydrothermalen Fluide an bestimmten Gasen wie CH4 und H2 sehr stark angereichert, was intensive Auswirkungen auf die an das Hydrothermalsystem gekoppelten Mikroorganismen hat. Die Mikroben sitzen auf den Oberflächen der Untergrundgesteine und Mineralpräzipitate im Bereich der hydrothermalen Austrittsstellen, wobei letztere spezifische ökologische Nischen bilden. Neben der Untersuchung der Tiefenzonierungen der Mineralisationen und Alterationen sowie deren Altersstellungen, ist die vermutete direkte Interaktion zwischen den Mikroorganismen (subsurface biosphere) und den hydrothermalen Mineralbildungen ein weiterer wichtiger wissenschaftlicher Aspekt. Auf der MSM03/2-Reise wird erstmals das ferngesteuerte Bohrgerät Rockdrill2 des British Geological Survey eingesetzt. Neben deutschen Wissenschaftlern der Fachrichtungen Lagerstättenkunde, Petrologie, Geochemie und Mikrobiologie werden britische Techniker und Ingenieure sowie Wissenschaftler aus Russland und China an der Fahrt teilnehmen.
Background: Ever decreasing costs along with advances in sequencing and library preparation technologies enable even small research groups to generate chromosome-level assemblies today. Here we report the generation of an improved chromosome-level assembly for the Siamese fighting fish (Betta splendens) that was carried out during a practical university Master’s course. The Siamese fighting fish is a popular aquarium fish and an emerging model species for research on aggressive behaviour. We updated the current genome assembly by generating a new long-read nanopore-based assembly with subsequent scaffolding to chromosome-level using previously published HiC data.
Findings: The use of nanopore-based long-read data sequenced on a MinION platform (Oxford Nanopore Technologies) allowed us to generate a baseline assembly of only 1,276 contigs with a contig N50 of 2.1 Mbp, and a total length of 441 Mbp. Scaffolding using previously published HiC data resulted in 109 scaffolds with a scaffold N50 of 20.7 Mbp. More than 99% of the assembly is comprised in 21 scaffolds. The assembly showed the presence of 95.8% complete BUSCO genes from the Actinopterygii dataset indicating a high quality of the assembly.
Conclusion: We present an improved full chromosome-level assembly of the Siamese fighting fish generated during a university Master’s course. The use of ~35× long-read nanopore data drastically improved the baseline assembly in terms of continuity. We show that relatively in-expensive high-throughput sequencing technologies such as the long-read MinION sequencing platform can be used in educational settings allowing the students to gain practical skills in modern genomics and generate high quality results that benefit downstream research projects.
Background Multimorbidity is a highly frequent condition in older people, but well designed longitudinal studies on the impact of multimorbidity on patients and the health care system have been remarkably scarce in numbers until today. Little is known about the long term impact of multimorbidity on the patients' life expectancy, functional status and quality of life as well as health care utilization over time. As a consequence, there is little help for GPs in adjusting care for these patients, even though studies suggest that adhering to present clinical practice guidelines in the care of patients with multimorbidity may have adverse effects. Methods The study is designed as a multicentre prospective, observational cohort study of 3.050 patients aged 65 to 85 at baseline with at least three different diagnoses out of a list of 29 illnesses and syndromes. The patients will be recruited in approx. 120 to 150 GP surgeries in 8 study centres distributed across Germany. Information about the patients' morbidity will be collected mainly in GP interviews and from chart reviews. Functional status, resources/risk factors, health care utilization and additional morbidity data will be assessed in patient interviews, in which a multitude of well established standardized questionnaires and tests will be performed. Discussion The main aim of the cohort study is to monitor the course of the illness process and to analyse for which reasons medical conditions are stable, deteriorating or only temporarily present. First, clusters of combinations of diseases/disorders (multimorbidity patterns) with a comparable impact (e.g. on quality of life and/or functional status) will be identified. Then the development of these clusters over time will be analysed, especially with regard to prognostic variables and the somatic, psychological and social consequences as well as the utilization of health care resources. The results will allow the development of an instrument for prediction of the deterioration of the illness process and point at possibilities of prevention. The practical consequences of the study results for primary care will be analysed in expert focus groups in order to develop strategies for the inclusion of the aspects of multimorbidity in primary care guidelines.
This Letter presents the first measurement of event-by-event fluctuations of the net number (difference between the particle and antiparticle multiplicities) of multistrange hadrons Ξ− and Ξ¯¯¯¯+ and its correlation with the net-kaon number using the data collected by the ALICE Collaboration in pp, p−Pb, and Pb−Pb collisions at a center-of-mass energy per nucleon pair sNN−−−√=5.02 TeV. The statistical hadronization model with a correlation over three units of rapidity between hadrons having the same and opposite strangeness content successfully describes the results. On the other hand, string-fragmentation models that mainly correlate strange hadrons with opposite strange quark content over a small rapidity range fail to describe the data.
he first measurement of 3ΛH and 3Λ¯¯¯¯H¯¯¯¯ differential production with respect to transverse momentum and centrality in Pb−Pb collisions at sNN−−−√=5.02~TeV is presented. The 3ΛH has been reconstructed via its two-charged-body decay channel, i.e., 3ΛH→3He+π−. A Blast-Wave model fit of the pT-differential spectra of all nuclear species measured by the ALICE collaboration suggests that the 3ΛH kinetic freeze-out surface is consistent with that of other nuclei. The ratio between the integrated yields of 3ΛH and 3He is compared to predictions from the statistical hadronisation model and the coalescence model, with the latter being favoured by the presented measurements.
First measurements of hadron(h)−Λ azimuthal angular correlations in p−Pb collisions at sNN−−−√ = 5.02 TeV using the ALICE detector at the LHC are presented. These correlations are used to separate the production of associated Λ baryons into three different kinematic regions, namely those produced in the direction of the trigger particle (near-side), those produced in the opposite direction (away-side), and those whose production is uncorrelated with the jet-axis (underlying event). The per-trigger associated Λ yields in these regions are extracted, along with the near- and away-side azimuthal peak widths, and the results are studied as a function of associated particle pT and event multiplicity. Comparisons with the DPMJET event generator and previous measurements of the ϕ(1020) meson are also made. The final results indicate that strangeness production in the highest multiplicity p−Pb collisions is enhanced relative to low multiplicity collisions in the jet-like regions, as well as the underlying event. The production of Λ relative to charged hadrons is also enhanced in the underlying event when compared to the jet-like regions. Additionally, the results hint that strange quark production in the away-side of the jet is modified by soft interactions with the underlying event.
Measurements of (anti)deuteron and (anti)3He production in the rapidity range |y|< 0.5 as a function of the transverse momentum and event multiplicity in Xe−Xe collisions at a center-of-mass energy per nucleon−nucleon pair of sNN−−−√ = 5.44 TeV are presented. The coalescence parameters B2 and B3 are measured as a function of the transverse momentum per nucleon. The ratios between (anti)deuteron and (anti)3He yields and those of (anti)protons and pions are reported as a function of the mean charged-particle multiplicity density, and compared with two implementations of the statistical hadronization model (SHM) and with coalescence predictions. The elliptic flow of (anti)deuterons is measured for the first time in Xe−Xe collisions and shows features similar to those already observed in Pb−Pb collisions, i.e., the mass ordering at low transverse momentum and the meson−baryon grouping at intermediate transverse momentum. The production of nuclei is particularly sensitive to the chemical freeze-out temperature of the system created in the collision, which is extracted from a grand-canonical-ensemble-based thermal fit, performed for the first time including light nuclei along with light-flavor hadrons in Xe−Xe collisions. The extracted chemical freeze-out temperature Tchem = (154.2 ± 1.1) MeV in Xe−Xe collisions is similar to that observed in Pb−Pb collisions and close to the crossover temperature predicted by lattice QCD calculations.
The intense photon fluxes from relativistic nuclei provide an opportunity to study photonuclear interactions in ultraperipheral collisions. The measurement of coherently photoproduced π+π−π+π− final states in ultraperipheral Pb-Pb collisions at sNN−−−√=5.02 TeV is presented for the first time. The cross section, dσ/dy, times the branching ratio (ρ→π+π+π−π−) is found to be 47.8±2.3 (stat.)±7.7 (syst.) mb in the rapidity interval |y|<0.5. The invariant mass distribution is not well described with a single Breit-Wigner resonance. The production of two interfering resonances, ρ(1450) and ρ(1700), provides a good description of the data. The values of the masses (m) and widths (Γ) of the resonances extracted from the fit are m1=1385±14 (stat.)±3 (syst.) MeV/c2, Γ1=431±36 (stat.)±82 (syst.) MeV/c2, m2=1663±13 (stat.)±22 (syst.) MeV/c2 and Γ2=357±31 (stat.)±49 (syst.) MeV/c2, respectively. The measured cross sections times the branching ratios are compared to recent theoretical predictions.
The transverse momentum (pT) differential production cross section of the promptly-produced charm-strange baryon Ξ0c (and its charge conjugate Ξ0c¯¯¯¯¯¯) is measured at midrapidity via its hadronic decay into π+Ξ− in p−Pb collisions at a centre-of-mass energy per nucleon−nucleon collision sNN−−−√ = 5.02 TeV with the ALICE detector at the LHC. The Ξ0c nuclear modification factor (RpPb), calculated from the cross sections in pp and p−Pb collisions, is presented and compared with the RpPb of Λ+c baryons. The ratios between the pT-differential production cross section of Ξ0c baryons and those of D0 mesons and Λ+c baryons are also reported and compared with results at forward and backward rapidity from the LHCb Collaboration. The measurements of the production cross section of prompt Ξ0c baryons are compared with a model based on perturbative QCD calculations of charm-quark production cross sections, which includes only cold nuclear matter effects in p−Pb collisions, and underestimates the measurement by a factor of about 50. This discrepancy is reduced when the data is compared with a model in which hadronisation is implemented via quark coalescence. The pT-integrated cross section of prompt Ξ0c-baryon production at midrapidity extrapolated down to pT = 0 is also reported. These measurements offer insights and constraints for theoretical calculations of the hadronisation process. Additionally, they provide inputs for the calculation of the charm production cross section in p−Pb collisions at midrapidity.