Ent-kaurane derivatives from the root cortex of yacon and other three Smallanthus species (Heliantheae,Asteraceae)

The metabolites produced by the secretory canals of the root cortex from four Smallanthus species belonging to the yacon group were identified as ent-kaurane-type diterpenes. The dichloromethane root cortex extracts of the four species were treated with diazomethane and analyzed comparatively by GC–MS using a simple and rapid procedure which is very sensitive and reproducible permitting detection of minor components. In all cases, ent-16-kauren-19-oic acid (kaurenoic acid) methyl ester was the main component, differences being observed only in the minor components. The minor components identified were grandiflorenic acid methyl ester, ent-16-kauren-19-al, 16α,17-epoxy-15α-angeloyloxy-kauran-19-oic acid methyl ester and several O-acyl derivatives at C-15 or C-18 of kaurenoic acid. One of the minor components, 18-isobutyroyloxy-ent-kaur-16-en-19-oic acid is a new kaurenoic acid derivative. Grandiflorenic acid and 15-α-angeloyloxy-16,17-α-epoxy-ent-16-kauren-19-oic acid were present only in Smallanthus sonchifolius and Smallanthus siegesbeckius which showed very similar GC traces. The different GC profile of RC diterpenes from Smallanthus connatus and Smallanthus macroscyphus supports the view that they are different taxa. Some chemotaxonomic aspects of the genus Smallanthus and the subtribe Milleriinae are briefly discussed.     

Identification of a conserved anti-apoptotic protein that modulates the mitochondrial apoptosis pathway

Here we identified an evolutionarily highly conserved and ubiquitously expressed protein (C9orf82) that shows structural similarities to the death effector domain of apoptosis-related proteins. RNAi knockdown of C9orf82 induced apoptosis in A-549 and MCF7/casp3-10b lung and breast carcinoma cells, respectively, but not in cells lacking caspase-3, caspase-10 or both. Apoptosis was associated with activated caspases-3, -8, -9 and -10, and inactivation of caspases 10 or 3 was sufficient to block apoptosis in this pathway. Apoptosis upon knockdown of C9orf82 was associated with increased caspase-10 expression and activation, which was required for the generation of an 11 kDa tBid fragment and activation of Caspase-9. These data suggest that C9orf82 functions as an anti-apoptotic protein that modulates a caspase-10 dependent mitochondrial caspase-3/9 feedback amplification loop. We designate this ubiquitously expressed and evolutionarily conserved anti-apoptotic protein Conserved Anti-Apoptotic Protein (CAAP). We also demonstrated that treatment of MCF7/casp3-10b cells with staurosporine and etoposides induced apoptosis and knockdown of CAAP expression. This implies that the CAAP protein could be a target for chemotherapeutic agents.     

Flood disturbance effects on benthic diatom assemblage structure in a semiarid river network

Disturbances such as floods and droughts play a central role in determining the structure of riverine benthic biological assemblages. Extreme disturbances from flash floods are often restricted to part of the river network and the magnitude of the flood disturbance may lessen as floods propagate downstream. The present study aimed to characterize the impact of summer monsoonal floods on the resistance and resilience of the benthic diatom assemblage structure in nine river reaches of increasing drainage size within the Gila River in the southwestern United States. Monsoonal floods had a profound effect on the diatom assemblage in the Gila River, but the effects were not related to drainage size except for the response of algal biomass. During monsoons, algal biomass was effectively reduced in smaller and larger systems, but minor changes were observed in medium systems. Resistance and resilience of the diatom assemblage to floods were related to specific species traits, mainly to growth forms. Tightly adhered, adnate and prostrate species (Achnanthidium spp., Cocconeis spp.) exhibited high resistance to repeated scour disturbance. Loosely attached diatoms, such as Nitzschia spp. and Navicula spp., were most susceptible to drift and scour. However, recovery of the diatom assemblage was very quick indicating a high resilience, especially in terms of biomass and diversity. Regional hydroclimatic models predict greater precipitation variability, which will select for diatoms resilient to bed‐mobilizing disturbances. The results of this study may help anticipate future benthic diatom assemblage patterns in the southwestern United States resulting from a more variable climate.     

Coronatine,a more powerful elicitor for inducing taxane biosynthesis in Taxus media cell cultures than methyl jasmonate

Coronatine is a toxin produced by the pathogen Pseudomonas syringae. This compound has received much attention recently for its potential to act as a plant growth regulator and elicitor of plant secondary metabolism. To gain more insight into the mechanism by which elicitors can affect the biosynthesis of paclitaxel (Px) and related taxanes, the effect of coronatine (Cor) and methyl jasmonate (MeJA) on Taxus media cell cultures has been studied. For this study, a two-stage cell culture was established, in which cells were first cultured for 14 days in a medium optimised for growth, after which the cells were transferred to medium optimised for secondary metabolite production. The two elicitors were added to the medium at the beginning of the second stage. Total taxane production in the cell suspension was significantly enhanced by both elicitors, increasing from a maximum level of 8.14 mg/L in control conditions to 21.48 mg/L (day 12) with MeJA and 77.46 mg/L (day 16) with Cor. Expression analysis indicated that the txs, t13oh, t2oh, t7oh, dbat, pam, bata and dbtnbt genes were variably induced by the presence of the elicitors. Genes encoding enzymes involved in the formation of the polihydroxylated hypothetical intermediate (TXS, T13OH, T2OH, T7OH) and the phenylalanoil CoA chain (PAM) were stronger induced than those encoding enzymes catalysing the last steps of the Px biosynthetic pathway (DBAT, BAPT and DBTNBT). Notably, although taxane accumulation differed qualitatively and quantitatively following MeJA- or Cor-elicitation, gene expression induction patterns were similar, inferring that both elicitors may involve distinct but yet uncharacterised regulatory mechanisms.     

Elevated CO2 affects embryonic development and larval phototaxis in a temperate marine fish

As an effect of anthropogenic CO₂ emissions, the chemistry of the world's oceans is changing. Understanding how this will affect marine organisms and ecosystems are critical in predicting the impacts of this ongoing ocean acidification. Work on coral reef fishes has revealed dramatic effects of elevated oceanic CO₂ on sensory responses and behavior. Such effects may be widespread but have almost exclusively been tested on tropical reef fishes. Here we test the effects elevated CO₂ has on the reproduction and early life history stages of a temperate coastal goby with paternal care by allowing goby pairs to reproduce naturally in an aquarium with either elevated (ca 1400 μatm) CO₂ or control seawater (ca 370 μatm CO₂). Elevated CO₂ did not affect the occurrence of spawning nor clutch size, but increased embryonic abnormalities and egg loss. Moreover, we found that elevated CO₂ significantly affected the phototactic response of newly hatched larvae. Phototaxis is a vision‐related fundamental behavior of many marine fishes, but has never before been tested in the context of ocean acidification. Our findings suggest that ocean acidification affects embryonic development and sensory responses in temperate fishes, with potentially important implications for fish recruitment.     

Modelling the impact of agricultural management on soil carbon stocks at the regional scale: the role of lateral fluxes

Agricultural management has received increased attention over the last decades due to its central role in carbon (C) sequestration and greenhouse gas mitigation. Yet, regardless of the large body of literature on the effects of soil erosion by tillage and water on soil organic carbon (SOC) stocks in agricultural landscapes, the significance of soil redistribution for the overall C budget and the C sequestration potential of land management options remains poorly quantified. In this study, we explore the role of lateral SOC fluxes in regional scale modelling of SOC stocks under three different agricultural management practices in central Belgium: conventional tillage (CT), reduced tillage (RT) and reduced tillage with additional carbon input (RT+i). We assessed each management scenario twice: using a conventional approach that did not account for lateral fluxes and an alternative approach that included soil erosion‐induced lateral SOC fluxes. The results show that accounting for lateral fluxes increased C sequestration rates by 2.7, 2.5 and 1.5 g C m^?2 yr^?1 for CT, RT and RT+i, respectively, relative to the conventional approach. Soil redistribution also led to a reduction of SOC concentration in the plough layer and increased the spatial variability of SOC stocks, suggesting that C sequestration studies relying on changes in the plough layer may underestimate the soil's C sequestration potential due to the effects of soil erosion. Additionally, lateral C export from cropland was in the same of order of magnitude as C sequestration; hence, the fate of C exported from cropland into other land uses is crucial to determine the ultimate impact of management and erosion on the landscape C balance. Consequently, soil management strategies targeting C sequestration will be most effective when accompanied by measures that reduce soil erosion given that erosion loss can balance potential C uptake, particularly in sloping areas.     

Targets for TNF-alpha-induced lipolysis in human adipocytes

BACKGROUND: Tumor necrosis factor-alpha (TNF-alpha)-induced lipolysis may be important for insulin resistance in both obesity and cachexia. In rodent cells TNF-alpha enhances lipolysis through down-regulation of the expression of the membrane proteins Galpha(i) and the lipid droplet-associated protein perilipin (PLIN). In human (but not murine) adipocytes TNF-alpha stimulates lipolysis through the mitogen activated protein kinases (MAPKs) p44/42 and JNK although it is unclear whether this is mediated via PLIN and/or Galpha(i). METHODS: Galpha(i) and PLIN as down-stream effectors of MAPKs were assessed in human adipocytes stimulated with TNF-alpha in the absence or presence of specific MAPK inhibitors. RESULTS: A 48-h incubation with TNF-alpha resulted in a pronounced increase in lipolysis, which was paralleled by a decrease in the mRNA and protein expression of PLIN. Both these effects were inhibited in a concentration-dependent manner in the presence of MAPK inhibitors specific for p44/42 (PD98059) and JNK (SP600125). However, TNF-alpha did not affect Galpha(i) mRNA or protein expression. Furthermore, experiments with pertussis toxin demonstrated that inhibition of Galpha(i) signaling did not affect TNF-alpha-mediated lipolysis. CONCLUSIONS: Our results suggest that TNF-alpha-mediated lipolysis is dependent on down-regulation of PLIN expression via p44/42 and JNK. This could be an important mechanism for the development of insulin resistance in both obesity and cachexia. However, in contrast to findings in rodent cells, Galpha(i) does not appear to be essential for TNF-alpha-induced lipolysis in human adipocytes.     

Development of a fast solid-phase enzyme immunoassay for C-reactive protein

A fast sandwich enzyme immunoassay has been developed for C-reactive protein (CRP). This method can be used for screening CRP concentration in large numbers of samples providing a non precipitation, non agglutination and non radioactive alternative for assessment of human CRP. Advantages over previously reported CRP sandwich assays include: assay time was reduced from 4 1/2 h to 45 min, incubations were made at room temperature instead of 37 degrees C and serum dilutions required were 100-400 fold instead of 10000-20000 fold. Correlations were good with both nephelometry and phosphorylethanolamine binding assay. The 45% false positives found with the slide-latex anti C-reactive protein method were reduced to 0% by the use of the described method.