The co-chaperone HOP3 participates in jasmonic acid signaling by regulating CORONATINE-INSENSITIVE 1 activity

HOPs (HSP70–HSP90 organizing proteins) are a highly conserved family of HSP70 and HSP90 co-chaperones whose role in assisting the folding of various hormonal receptors has been extensively studied in mammals. In plants, HOPs are mainly associated with stress response, but their potential involvement in hormonal networks remains completely unexplored. In this article we describe that a member of the HOP family, HOP3, is involved in the jasmonic acid (JA) pathway and is linked to plant defense responses not only to pathogens, but also to a generalist herbivore. The JA pathway regulates responses to Botrytis cinerea infection and to Tetranychus urticae feeding; our data demonstrate that the Arabidopsis (Arabidopsis thaliana) hop3-1 mutant shows an increased susceptibility to both. The hop3-1 mutant exhibits reduced sensitivity to JA derivatives in root growth assays and downregulation of different JA-responsive genes in response to methyl jasmonate, further revealing the relevance of HOP3 in the JA pathway. Interestingly, yeast two-hybrid assays and in planta co-immunoprecipitation assays found that HOP3 interacts with COI1, suggesting that COI1 is a target of HOP3. Consistent with this observation, COI1 activity is reduced in the hop3-1 mutant. All these data strongly suggest that, specifically among HOPs, HOP3 plays a relevant role in the JA pathway by regulating COI1 activity in response to JA and, consequently, participating in defense signaling to biotic stresses.

One-sentence summary: The co-chaperone protein HOP3 (HSP70-HSP90 ORGANIZING PROTEIN 3) regulates the activity of jasmonic acid co-receptor CORONATINE INSENSITIVE 1 and functions in plant defense.     

Effect of Polymer–Fullerene Interaction on the Dielectric Properties of the Blend

It is commonly believed that large dielectric constants are required for efficient charge separation in polymer photovoltaic devices. However, many polymers used in high‐performance solar cells do not possess high dielectric constants. In this work, the effect of polymer–fullerene interactions on the dielectric environment of the active layer blend and the device performance for several donor–acceptor conjugated polymer systems is investigated. It is found that, while none of the high‐performing polymers studied has a dielectric constant value larger than 3, all polymer–fullerene blends have a significantly larger dielectric constant compared to their pristine constituents. Additionally, it is found that the blend dielectric constant reaches a maximum value in fully optimized devices. Using PTB7:PC₇₁BM blends as an example, it is showed that, in addition to a small increase in the dielectric constant, devices fabricated using the optimum processing additive concentration exhibit almost 3X larger excited state polarizability. This large increase in excited state polarizability results in a substantial difference in short‐circuit current and ultimately device performance. The results show that the excited state polarizability critically depends on polymer–fullerene interactions, and can be a leading indicator of device performance for a given material system.     

Deprotonation of glutamic acid induced by weak magnetic field: an FTIR-ATR study

It has been claimed that weak extremely low frequency electromagnetic fields (ELF‐EMFs) can affect biochemical reactions and a wide‐ranging body of literature is available on this topic. Nevertheless, the physical nature of these effects remains largely unknown. We investigated the influence of ELF‐EMF on glutamic acid solutions using Fourier transform infrared‐attenuated total reflectance (FTIR‐ATR) spectra. Samples were exposed for 10, 20, or 30 min to a weak EMF generated by Helmoltz coils, and then placed in a spectrometer. After exposure, those solutions that had a pH lower than the isoelectric point tended to show a shift toward the deprotonation of the carboxylic group, while solutions having a pH greater than the isoelectric point showed the deprotonation of the residual amine group. Moreover, at low pH values, we also detected a shift of the δ_antisym band of the amine. The effects lasted a few minutes after exposure before the native configuration was restored. The spectral modifications were observed after each independent exposure to EMFs, and the same effects were seen by varying the frequencies in the range of 0–7 kHz. Therefore, the hypothesis of the existence of a resonant frequency that has been proposed elsewhere cannot be supported by the results of this study. The most surprising characteristic of this effect is the long‐lasting nature of the perturbation, which is hard to be explained in terms of short‐living excitations in biological matter. Bioelectromagnetics 32:218–225, 2011. © 2010 Wiley‐Liss, Inc.     

Myrtucommulone production by a strain of Neofusicoccum australe endophytic in myrtle (Myrtus communis)

Myrtucommulones are acylphloroglucinol compounds reported from myrtle (Myrtus communis) and a few more plant species belonging in the Myrtaceae that have recently attracted the attention of pharmacologists for their anti-oxidant, anti-inflammatory and anti-tumor properties. An endophytic strain of Neofusicoccum australe recovered from a myrtle branch was selected based on the bioactivity of its culture extracts, and found to produce myrtucommulones A and D. A mixture of these compounds induced anti-proliferative effects on the human prostatic cancer cell lines DU145 and PC3, with a IC₅₀ of respectively 4.64 and 3.11 mg/l. Along the lines of recent evidences of the ability by endophytic fungi to produce bioactive compounds originally extracted from their host plants, this is the first report of myrtucommulones as secondary metabolites of an endophytic fungal strain. The availability of a microbial strain to be cultured in vitro may provide access to more substantial amounts of these products for further investigations in view of their possible pharmaceutical use.     

Micelle‐enhanced spectrofluorimetric method for determination of sitagliptin and identification of potential alkaline degradation products using LC‐MS

A novel, quick, simple and highly sensitive spectrofluorimetric method was developed and validated for the determination of sitagliptin (SG) in its pharmaceutical formulations. The proposed method is based on investigation of the fluorescence spectral behavior of sitagliptin in an SDS micellar system. In an aqueous solution of phosphate buffer pH 4.0, the fluorescence intensity of SG in the presence of SDS was greatly enhanced, by 200%, i.e. twofold enhancement. The fluorescence intensity of SG was measured at 300 nm after excitation at 270 nm. The method showed good linearity in the range 0.03–10.0 µg/mL with a good correlation coefficient (r = 0.9998). The limits of detection and quantitation values were 5.31 and 16.1 ng/mL, respectively. The proposed method was successfully applied to the analysis of SG in its single and co‐formulated commercial tablets; the results were in good agreement with those obtained using a reference method. Application of the proposed method was extended to stability studies of SG after exposure to different forced degradation conditions according to the ICH guidelines, such as acidic, alkaline, thermal, photo‐ and oxidative stress. The chemical structure of certain potential degradation products (DPs) were investigated using LC‐MS. Copyright © 2013 John Wiley & Sons, Ltd.     

Linking Environmental Forcing and Trophic Supply to Benthic Communities in the Vercelli Seamount Area (Tyrrhenian Sea)

Seamounts and their influence on the surrounding environment are currently being extensively debated but, surprisingly, scant information is available for the Mediterranean area. Furthermore, although the deep Tyrrhenian Sea is characterised by a complex bottom morphology and peculiar hydrodynamic features, which would suggest a variable influence on the benthic domain, few studies have been carried out there, especially for soft-bottom macrofaunal assemblages. In order to fill this gap, the structure of the meio-and macrofaunal assemblages of the Vercelli Seamount and the surrounding deep area (northern Tyrrhenian Sea – western Mediterranean) were studied in relation to environmental features. Sediment was collected with a box-corer from the seamount summit and flanks and at two far-field sites in spring 2009, in order to analyse the metazoan communities, the sediment texture and the sedimentary organic matter. At the summit station, the heterogeneity of the habitat, the shallowness of the site and the higher trophic supply (water column phytopigments and macroalgal detritus, for instance) supported a very rich macrofaunal community, with high abundance, biomass and diversity. In fact, its trophic features resembled those observed in coastal environments next to seagrass meadows. At the flank and far-field stations, sediment heterogeneity and depth especially influenced the meiofaunal distribution. From a trophic point of view, the low content of the valuable sedimentary proteins that was found confirmed the general oligotrophy of the Tyrrhenian Sea, and exerted a limiting influence on the abundance and biomass of the assemblages. In this scenario, the rather refractory sedimentary carbohydrates became a food source for metazoans, which increased their abundance and biomass at the stations where the hydrolytic-enzyme-mediated turnover of carbohydrates was faster, highlighting high lability.