71 research outputs found
Fungal association and root morphology shift stepwise during ontogenesis of orchid Cremastra appendiculata towards autotrophic nutrition
The chlorophyllous, terrestrial orchid Cremastra appendiculata from East Asia is unique concerning its fungal mycorrhiza partners. The initially mycoheterotrophic protocorms exploit rather specialized non-rhizoctonia saprotrophic Psathyrellaceae. Adult individuals of this orchid species are either linked to Psathyrellaceae being partially mycoheterotrophic or form mycorrhiza with fungi of the ubiquitous saprotrophic rhizoctonia group. This study provides new insights on nutrition mode, subterranean morphology and fungal partners across different life stages of C. appendiculata. We compared different development stages of C. appendiculata to surrounding autotrophic reference plants based on multi-element natural abundance stable isotope analyses (ÎŽ(13)C, ÎŽ(15)N, ÎŽ(2)H, ÎŽ(18)O) and total N concentrations. Site- and sampling-time-independent enrichment factors of stable isotopes were used to reveal trophic strategies. We determined mycorrhizal fungi of C. appendiculata protocorm, seedling and adult samples using high-throughput DNA sequencing. We identified saprotrophic non-rhizoctonia Psathyrellaceae as dominant mycorrhizal fungi in protocorm and seedling rhizomes. In contrast, the roots of seedlings and mature C. appendiculata were mainly colonized with fungi belonging to the polyphyletic assembly of rhizoctonia (Ceratobasidium, Thanatephorus and Serendipitaceae). Mature C. appendiculata did not differ in isotopic signature from autotrophic reference plants suggesting a fully autotrophic nutrition mode. Characteristic of orchid specimens entirely relying on fungal nutrition, C. appendiculata protocorms were enriched in (15)N, (13)C and (2)H compared to reference plants. Seedlings showed an intermediate isotopic signature, underpinning the differences in the fungal community depending on their subterranean morphology. In contrast to the suggestion that C. appendiculata is a partially mycoheterotrophic orchid species, we provide novel evidence that mature C. appendiculata with rhizoctonia mycobionts can be entirely autotrophic. Besides an environmentally driven variability among populations, we suggest high within-individual flexibility in nutrition and mycobionts of C. appendiculata, which is subject to the ontogenetic development stage
Die Auswirkungen des Fortschritts, der beim Umschlag, Laden und Löschen von StĂŒckgut, Massengut, mit Containern und in TrĂ€gerschiffsleichtern (einschlieĂlich gefĂ€hrlicher GĂŒter) erzielt wurde, auf die Anlage und Ausstattung von Wasserstrassen und BinnenhĂ€fen
A new cavity ring-down instrument for airborne monitoring of N2O5, NO3, NO2 and O3 in the upper troposphere lower stratosphere
A new airborne instrument based on pulsed cavity ring-down spectroscopy for simultaneous detection of N2O5, NO3, NO2 and O3 in the upper troposphere lower stratosphere is being developed for global atmospheric monitoring. OCIS codes: 010.0010, 120.0120, 140.0140, 280.0280, 300.0300, 300.6260, 300.6360
Novel insights into orchid mycorrhiza functioning from stable isotope signatures of fungal pelotons
Frontotemporal lobar degeneration and social behaviour:Dissociation between the knowledge of its consequences and its conceptual meaning
GiSAO.db: a database for ageing research
<p>Abstract</p> <p>Background</p> <p>Age-related gene expression patterns of <it>Homo sapiens </it>as well as of model organisms such as <it>Mus musculus</it>, <it>Saccharomyces cerevisiae</it>, <it>Caenorhabditis elegans </it>and <it>Drosophila melanogaster </it>are a basis for understanding the genetic mechanisms of ageing. For an effective analysis and interpretation of expression profiles it is necessary to store and manage huge amounts of data in an organized way, so that these data can be accessed and processed easily.</p> <p>Description</p> <p>GiSAO.db (Genes involved in senescence, apoptosis and oxidative stress database) is a web-based database system for storing and retrieving ageing-related experimental data. Expression data of genes and miRNAs, annotation data like gene identifiers and GO terms, orthologs data and data of follow-up experiments are stored in the database. A user-friendly web application provides access to the stored data. KEGG pathways were incorporated and links to external databases augment the information in GiSAO.db. Search functions facilitate retrieval of data which can also be exported for further processing.</p> <p>Conclusions</p> <p>We have developed a centralized database that is very well suited for the management of data for ageing research. The database can be accessed at <url>https://gisao.genome.tugraz.at</url> and all the stored data can be viewed with a guest account.</p
Stellar Processes Near the Massive Black Hole in the Galactic Center
A massive black hole resides in the center of most, perhaps all galaxies. The
one in the center of our home galaxy, the Milky Way, provides a uniquely
accessible laboratory for studying in detail the connections and interactions
between a massive black hole and the stellar system in which it grows; for
investigating the effects of extreme density, velocity and tidal fields on
stars; and for using stars to probe the central dark mass and probe
post-Newtonian gravity in the weak- and strong-field limits. Recent results,
open questions and future prospects are reviewed in the wider context of the
theoretical framework and physical processes that underlie them.
Contents: [1] Introduction (1.1) Astrophysical context (1.2) Science
questions (1.3) Scope and connections to related topics [2] Observational
overview: Stars in the Galactic center (2.1) The central 100 parsecs (2.2) The
central parsec [3] Stellar dynamics at extreme densities (3.1) Physical
processes and scales (3.2) The stellar cusp in the Galactic center (3.3) Mass
segregation (3.4) Stellar Collisions [4] Probing the dark mass with stellar
dynamics (4.1) Weighing and pinpointing the dark mass (4.2) Constraints on
non-BH dark mass alternatives (4.3) Limits on MBH binarity (4.4) High-velocity
runaway stars [5] Probing post-Newtonian gravity near the MBH (5.1)
Relativistic orbital effects (5.2) Gravitational lensing [6] Strong star-MBH
interactions (6.1) Tidal disruption (6.2) Dissipative interactions with the MBH
[7] The riddle of the young stars (7.1) The difficulties of forming or
importing stars near a MBH (7.2) Proposed solutions (7.3) Feeding the MBH with
stellar winds [8] Outlook (8.1) Progress report (8.2) Future directionsComment: Invited review article, to appear in Physics Reports. 101 p
Dynamics of charged gibbsite platelets in the isotropic phase
We report on depolarized and non-depolarized dynamic light scattering, static
light scattering, and static viscosity measurements on interacting charged
gibbsite platelets suspended in dimethyl sulfoxide (DMSO). The average
collective and (long-time) translational self-diffusion coefficients, and the
rotational diffusion coefficient, have been measured as functions of the
platelet volume fraction \phi, up to the isotropic-liquid crystal (I/LC)
transition. The non-depolarized intensity autocorrelation function, measured at
low scattering wavenumbers, consists of a fast and a slowly decaying mode which
we interpret as the orientationally averaged collective and translational
self-diffusion coefficients, respectively. Both the rotational and the
long-time self-diffusion coefficients decrease very strongly, by more than two
orders of magnitude, in going from the very dilute limit to the I/LC transition
concentration. A similarly strong decrease, with increasing \phi, is observed
for the inverse zero-strain limiting static shear viscosity. With increasing
\phi, increasingly strong shear-thinning is observed, accompanied by a
shrinking of the low shear-rate Newtonian plateau. The measured diffusion
coefficients are interpreted theoretically in terms of a simple model of
effective charged spheres interacting by a screened Coulomb potential, with
hydrodynamic interactions included. The disk-like particle shape, and the
measured particle radius and thickness polydispersities, enter into the model
calculations via the scattering amplitudes. The interaction-induced enhancement
of the collective diffusion coefficient by more than a factor of 20 at larger
volume fractions is well captured in the effective sphere model, whereas the
strong declines both of the experimental translational and rotational
self-diffusion coefficients are underestimated
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