Interaction of lignans with human sex hormone binding globulin (SHBG)

Lignans bind to sex hormone-binding globulin (SHBG). The lignan with the highest binding affinity is (±)-3,4-divanillyltetrahydrofuran. In a double Stobbe condensation - without use of protecting groups - a wide variety of lignans with different substitution pattern in the aromatic and aliphatic part of the molecule was synthesized. These lignans were tested in a SHBG-binding assay which allowed to deduce the following relationship between structure and activity: 1) (±)-diastereoisomers are more active than meso compounds 2.) the 4-hydroxy-3-methoxy (guajacyl) substitution pattern in the aromatic part is most effective 3.) the activity increases with the decline in polarity of the aliphatic part of the molecule

Microbial community composition of deep-sea corals from the Red Sea provides insight into functional adaption to a unique environment

Microbes associated with deep-sea corals remain poorly studied. The lack of symbiotic algae suggests that associated microbes may play a fundamental role in maintaining a viable coral host via acquisition and recycling of nutrients. Here we employed 16 S rRNA gene sequencing to study bacterial communities of three deep-sea scleractinian corals from the Red Sea, Dendrophyllia sp., Eguchipsammia fistula, and Rhizotrochus typus. We found diverse, species-specific microbiomes, distinct from the surrounding seawater. Microbiomes were comprised of few abundant bacteria, which constituted the majority of sequences (up to 58% depending on the coral species). In addition, we found a high diversity of rare bacteria (taxa at 90% of all bacteria). Interestingly, we identified anaerobic bacteria, potentially providing metabolic functions at low oxygen conditions, as well as bacteria harboring the potential to degrade crude oil components. Considering the presence of oil and gas fields in the Red Sea, these bacteria may unlock this carbon source for the coral host. In conclusion, the prevailing environmental conditions of the deep Red Sea (>20 °C, <2 mg oxygen L−1) may require distinct functional adaptations, and our data suggest that bacterial communities may contribute to coral functioning in this challenging environment.This work was supported from baseline funds to CRV and under the Center Competitive Funding (CCF) Program FCC/1/1973-18-01 by the King Abdullah University of Science and Technology (KAUST)

Spatial Scales of Bacterial Diversity in Cold-Water Coral Reef Ecosystems

Background: Cold-water coral reef ecosystems are recognized as biodiversity hotspots in the deep sea, but insights into their associated bacterial communities are still limited. Deciphering principle patterns of bacterial community variation over multiple spatial scales may however prove critical for a better understanding of factors contributing to cold-water coral reef stability and functioning. Methodology/Principal Findings: Bacterial community structure, as determined by Automated Ribosomal Intergenic Spacer Analysis (ARISA), was investigated with respect to (i) microbial habitat type and (ii) coral species and color, as well as the three spatial components (iii) geomorphologic reef zoning, (iv) reef boundary, and (v) reef location. Communities revealed fundamental differences between coral-generated (branch surface, mucus) and ambient microbial habitats (seawater, sediments). This habitat specificity appeared pivotal for determining bacterial community shifts over all other study levels investigated. Coral-derived surfaces showed species-specific patterns, differing significantly between Lophelia pertusa and Madrepora oculata, but not between L. pertusa color types. Within the reef center, no community distinction corresponded to geomorphologic reef zoning for both coral-generated and ambient microbial habitats. Beyond the reef center, however, bacterial communities varied considerably from local to regional scales, with marked shifts toward the reef periphery as well as between different in- and offshore reef sites, suggesting significant biogeographic imprinting but wea

Diversity and dynamics of rare and of resident bacterial populations in coastal sands

Coastal sands filter and accumulate organic and inorganic materials from the terrestrial and marine environment, and thus provide a high diversity of microbial niches. Sands of temperate climate zones represent a temporally and spatially highly dynamic marine environment characterized by strong physical mixing and seasonal variation. Yet little is known about the temporal fluctuations of resident and rare members of bacterial communities in this environment. By combining community fingerprinting via pyrosequencing of ribosomal genes with the characterization of multiple environmental parameters, we disentangled the effects of seasonality, environmental heterogeneity, sediment depth and biogeochemical gradients on the fluctuations of bacterial communities of marine sands. Surprisingly, only 3–5% of all bacterial types of a given depth zone were present at all times, but 50–80% of them belonged to the most abundant types in the data set. About 60–70% of the bacterial types consisted of tag sequences occurring only once over a period of 1 year. Most members of the rare biosphere did not become abundant at any time or at any sediment depth, but varied significantly with environmental parameters associated with nutritional stress. Despite the large proportion and turnover of rare organisms, the overall community patterns were driven by deterministic relationships associated with seasonal fluctuations in key biogeochemical parameters related to primary productivity. The maintenance of major biogeochemical functions throughout the observation period suggests that the small proportion of resident bacterial types in sands perform the key biogeochemical processes, with minimal effects from the rare fraction of the communities

Temporal segmentation in hand movements of chimpanzees (Pan troglodytes) and comparisons with humans

Hand movements action units in chimpanzees show temporal segmentation similar to but shorter than that in humans; median durations are 0.9 s in non-repetitive behaviour and 2.4 s in repetitive behaviour (vs. 2.0 s and 3.0 s in humans: SCHLEIDT 1988; FLEDHUTTER et al. 1990). In neither chimpanzees nor humans does one repetition of a movement within an action unit increase the duration of the action unit; each further repetition of movements in the action unit tends to prolong it by only 0.5-1 s. Thus, in both chimpanzees and humans, there appears to be some presyntactical planning in advance in repetitive hand movements. The quantitative differences in segment length may reflect uniquely human abilities of timing or sequencing muscle contractions. These findings fit well with current hypotheses that syntactical ability in language could have evolved from mother organisation

Jasmonic acid does not mediate root growth responses to wounding in Arabidopsis thaliana

Jasmonic acid (JA) is a crucial plant defence signalling substance that has recently been shown to mediate herbivory-induced root growth reduction in the ecological model species Nicotiana attenuata. To clarify whether JA-induced reduction of root growth might be a general response increasing plant fitness under biotic stress, a suite of experiments was performed with the model plant Arabidopsis thaliana. JA bursts were elicited in leaves of A. thaliana in different ways. Root growth reduction was neither induced by foliar application of herbivore oral secretions nor by direct application of methyl jasmonate to leaves. Root growth reduction was observed when leaves were infected with the pathogen Pseudomonas syringae pv. tomato, which persistently induces the JA signalling pathway. Yet, high resolution growth analyses of this effect in wild type and JA biosynthesis knock-out mutants showed that it was elicited by the bacterial toxin coronatine that suggests ethylene- but not JA-induced root growth reduction in A. thaliana. Overall, the results demonstrate that the reaction of root growth to herbivore-induced JA signalling differs among species, which is discussed in the context of different ecological defence strategies among species