Complete NMR characterization of lychnose from Stellaria media (L.) Vill

Lychnose (alpha-D-Gal-(1-->6)-alpha-D-Glc-(1-->2)-beta-D-Fru-(1-->1)-alpha-D-Gal) was isolated from Stellaria media, a representative member of the Caryophyllaceae plant family. Weak acid hydrolysis, enzymatic hydrolysis and complete NMR characterization were performed to confirm the identity of the tetrasaccharide. All (1)H and (13)C resonances were unambiguously assigned and the conformation of the sugars was determined using one and two dimensional NMR techniques. Anomeric characterizations in lychnose were confirmed from HMBC and NOESY spectra.status: publishe

Genome-wide characterization of ISR induced in Arabidopsis thaliana by Trichoderma hamatum T382 against Botrytis cinerea infection

In this study, the molecular basis of the induced systemic resistance (ISR) in Arabidopsis thaliana by the biocontrol fungus Trichoderma hamatum T382 against the phytopathogen Botrytis cinerea B05-10 was unraveled by microarray analysis both before (ISR-prime) and after (ISR-boost) additional pathogen inoculation. The observed high numbers of differentially expressed genes allowed us to classify them according to the biological pathways in which they are involved. By focusing on pathways instead of genes, a holistic picture of the mechanisms underlying ISR emerged. In general, a close resemblance is observed between ISR-prime and systemic acquired resistance (SAR), the systemic defense response that is triggered in plants upon pathogen infection leading to increased resistance towards secondary infections. Treatment with Trichoderma hamatum T382 primes the plant (ISR-prime), resulting in an accelerated activation of the defense response against Botrytis cinerea during ISR-boost and a subsequent moderation of the Botrytis cinerea induced defense response (BIDR). Microarray results were validated for representative genes by qRT-PCR. The involvement of various defense-related pathways was confirmed by phenotypic analysis of mutants affected in these pathways, thereby proving the validity of our approach. Combined with additional anthocyanin analysis data these results all point to the involvement of the phenylpropanoid pathway in Trichoderma hamatum T382-induced ISR.status: publishe

Global cytosine methylation in Daphnia magna depends on genotype, environment and their interaction

The authors characterized global cytosine methylation levels in two different genotypes of the ecotoxicological model organism Daphnia magna after exposure to a wide array of biotic and abiotic environmental stressors. The study aimed to improve the authors' understanding of the role of cytosine methylation in the organism‘s response to environmental conditions. The authors observed a significant genotype effect, an environment effect and a genotype x environment effect. In particular, global cytosine methylation levels were significantly altered after exposure to Triops predation cues, Microcystis and sodium chloride compared to control conditions. Significant differences between the two genotypes were observed when animals were exposed to Triops predation cues, Microcystis, Cryptomonas and sodium chloride. Despite the low global methylation rate under control conditions (0.49-0.52%), global cytosine methylation levels upon exposure to Triops demonstrated a five-fold difference between the genotypes (0.21% versus 1.02%). No effects were found in response to arsenic, cadmium, fish, lead, pH of 5.5, pH of 8, temperature, hypoxia and white fat cell disease. The authors’ results point to the potential role of epigenetic effects under changing environmental conditions such as predation (i.e. Triops), diet (i.e. Cryptomonas and Microcystis) and salinity. The current results indicate that, despite global cytosine methylation levels are low, epigenetic effects may be important in environmental studies on Daphnia. This article is protected by copyright. All rights reservedstatus: publishe

The importance of the terrigenous fraction within a cold-water coral mound: A case study

In the nineties, cold-water coral mounds were discovered in the Porcupine Seabight (NE Atlantic, west of Ireland). A decade later, this discovery led to the drilling of the entire Challenger cold-water coral mound (Eastern slope, Porcupine Seabight) during IODP Expedition 307. As more than 50% of the sediment within Challenger Mound consists of terrigenous material, the terrigenous component is equally important for the build-up of the mound as the framework-building corals. Moreover, the terrigenous fraction contains important information on the dynamics and the conditions of the depositional environment during mound development. In this study, the first in-depth investigation of the terrigenous sediment fraction of a cold-water coral mound is performed, combining clay mineralogy, sedimentology, petrography and Sr–Nd-isotopic analysis on a gravity core (MD01-2451G) collected at the top of Challenger Mound.Sr- and Nd-isotopic fingerprinting identifies Ireland as the main contributor of terrigenous material in Challenger Mound. Besides this, a variable input of volcanic material from the northern volcanic provinces (Iceland and/or the NW British Isles) is recognized in most of the samples. This volcanic material was most likely transported to Challenger Mound during cold climatic stages. In three samples, the isotopic ratios indicate a minor contribution of sediment deriving from the old cratons on Greenland, Scandinavia or Canada. The grain-size distributions of glacial sediments demonstrate that ice-rafted debris was deposited with little or no sorting, indicating a slow bottom-current regime. In contrast, interglacial intervals contain strongly current-sorted sediments, including reworked glacio-marine grains. The micro textures of the quartz-sand grains confirm the presence of grains transported by icebergs in interglacial intervals. These observations highlight the role of ice-rafting as an important transport mechanism of terrigenous material towards the mound during the Late Quaternary.Furthermore, elevated smectite content in the siliciclastic, glaciomarine sediment intervals is linked to the deglaciation history of the British-Irish Ice Sheet (BIIS). The increase of smectite is attributed to the initial stage of chemical weathering processes, which became activated following glacial retreat and the onset of warmer climatic conditions. During these deglaciations a significant change in the signature of the detrital fraction and a lack of coral growth is observed. Therefore, we postulate that the deglaciation of the BIIS has an important effect on mound growth. It can seriously alter the hydrography, nutrient supply and sedimentation processes, thereby affecting both sediment input and coral growth and hence, coral mound development

Cold-water carbonate mounds as palaeo-archives : the Plio-Pleistocene sediment record from the Challenger Mound, northeast Atlantic

During IODP Expedition 307, the first (and so far only) complete sequence through a cold-water coral carbonate mound was successfully drilled. After decades of research on contemporary to sub-recent coral carbonate mound environments, the complete recovery of the Challenger Mound record, sampling one of the large mounds along the Irish sector of the NE Atlantic continental margin (eastern Porcupine Seabight; Belgica mound province), allowed for the first time the investigation of long-term mound development, from mound initiation to decline. Here, we present an overview of the palaeo-environmental (i.e. hydrodynamic, oceanographic and climatic) signal captured in the entire Challenger Mound sequence (Hole U1317E). A high-resolution multi-proxy characterisation of the ca. 155m long mound matrix sediment record was conducted, encompassing a wide array of sedimentological, mineralogical, geochemical and stratigraphic techniques. These included, amongst others, siliciclastic particle-size analysis, X-ray diffraction phase quantification, isotopic fingerprinting of target elements for provenance purposes, calcareous nannofossil and planktonic foraminifer biostratigraphy and assemblage counts. In this way we aimed to (1) identify the controls on Challenger Mound development throughout the different phases of its entire Plio-Pleistocene to recent build-up, and (2) assess the unique character of coral carbonate mounds as recorders of Quaternary palaeo-environmental change at intermediate water depth in the NE Atlantic. Overall, Challenger Mound development shows a strong affinity to the general climate variability of the Northern Hemisphere, although not being completely in phase with it. The major oceanographic and climatic rearrangements of the Plio-Pleistocene, such as those associated with the Late Pliocene/Early Pleistocene intensification of continental ice-sheet development (ca. 2.75 – 2.55 Ma)1 or the orbital frequency changes during the mid-Pleistocene climate transition (ca. 1.2 – 0.6 Ma)2, seem responsible for the two significant thresholds in Challenger Mound development: its Late Pliocene origin and its Middle-Late Pleistocene to recent decline. However, local influences such as proximal (British-Irish) ice-sheet dynamics and on-mound changes in cold-water coral density seem to have a stronger control on Challenger Mound development and may have induced the offset between global climate and Challenger Mound proxy record variability. On the other hand, owing to this, a unique, high-resolution palaeo-record of regional Early-Pleistocene environmental change (including early British-Irish ice-sheet development3) is preserved in the lower Challenger Mound, covering a period that is not recorded in the general sedimentary sequence of the area. The Challenger Mound record, albeit with restricted Late Quaternary preservation, highlights the potential of coral carbonate mounds as excellent palaeo-recorders, providing us with unique records from ‘complex’ continental margin environments