Resveratrol Induces Premature Senescence in Lung Cancer Cells via ROS-Mediated DNA Damage

Resveratrol (RV) is a natural component of red wine and grapes that has been shown to be a potential chemopreventive and anticancer agent. However, the molecular mechanisms underlying RV''s anticancer and chemopreventive effects are incompletely understood. Here we show that RV treatment inhibits the clonogenic growth of non-small cell lung cancer (NSCLC) cells in a dose-dependent manner. Interestingly, the tumor-suppressive effect of low dose RV was not associated with any significant changes in the expression of cleaved PARP and activated caspase-3, suggesting that low dose RV treatment may suppress tumor cell growth via an apoptosis-independent mechanism. Subsequent studies reveal that low dose RV treatment induces a significant increase in senescence-associated β–galactosidase (SA-β-gal) staining and elevated expression of p53 and p21 in NSCLC cells. Furthermore, we show that RV-induced suppression of lung cancer cell growth is associated with a decrease in the expression of EF1A. These results suggest that RV may exert its anticancer and chemopreventive effects through the induction of premature senescence. Mechanistically, RV-induced premature senescence correlates with increased DNA double strand breaks (DSBs) and reactive oxygen species (ROS) production in lung cancer cells. Inhibition of ROS production by N-acetylcysteine (NAC) attenuates RV-induced DNA DSBs and premature senescence. Furthermore, we show that RV treatment markedly induces NAPDH oxidase-5 (Nox5) expression in both A549 and H460 cells, suggesting that RV may increase ROS generation in lung cancer cells through upregulating Nox5 expression. Together, these findings demonstrate that low dose RV treatment inhibits lung cancer cell growth via a previously unappreciated mechanism, namely the induction of premature senescence through ROS-mediated DNA damage.     

Bringing Back a Healthy Buzz? Invertebrate Parasites and Reintroductions: A Case Study in Bumblebees

Reintroductions can play a key role in the conservation of endangered species. Parasites may impact reintroductions, both positively and negatively, but few case studies of how to manage parasites during reintroductions exist. Bumblebees are in decline at regional and global scales, and reintroductions can be used to re-establish extinct local populations. Here we report on how the risks associated with parasites are being managed in an ongoing reintroduction of the short-haired bumblebee, Bombus subterraneus, to the UK. Disease risk analysis was conducted and disease risk management plans constructed to design a capture-quarantine-release system that minimised the impacts on both the bumblebees and on their natural parasites. Given that bumblebee parasites are (i) generalists, (ii) geographically ubiquitous, and (iii) show evidence of local adaptation, the disease risk management plan was designed to limit the co-introduction of parasites from the source population in Sweden to the destination site in the UK. Results suggest that this process at best eliminated, or at least severely curtailed the co-introduction of parasites, and ongoing updates of the plan enabled minimization of impacts on natural host-parasite dynamics in the Swedish source population. This study suggests that methods designed for reintroductions of vertebrate species can be successfully applied to invertebrates. Future reintroductions of invertebrates where the parasite fauna is less well known should take advantage of next-generation barcoding and multiple survey years prior to the start of reintroductions, to develop comprehensive disease risk management plans.

     

A Framework to Assess Biogeochemical Response to Ecosystem Disturbance Using Nutrient Partitioning Ratios

Disturbances affect almost all terrestrial ecosystems, but it has been difficult to identify general principles regarding these influences. To improve our understanding of the long-term consequences of disturbance on terrestrial ecosystems, we present a conceptual framework that analyzes disturbances by their biogeochemical impacts. We posit that the ratio of soil and plant nutrient stocks in mature ecosystems represents a characteristic site property. Focusing on nitrogen (N), we hypothesize that this partitioning ratio (soil N: plant N) will undergo a predictable trajectory after disturbance. We investigate the nature of this partitioning ratio with three approaches: (1) nutrient stock data from forested ecosystems in North America, (2) a process-based ecosystem model, and (3) conceptual shifts in site nutrient availability with altered disturbance frequency. Partitioning ratios could be applied to a variety of ecosystems and successional states, allowing for improved temporal scaling of disturbance events. The generally short-term empirical evidence for recovery trajectories of nutrient stocks and partitioning ratios suggests two areas for future research. First, we need to recognize and quantify how disturbance effects can be accreting or depleting, depending on whether their net effect is to increase or decrease ecosystem nutrient stocks. Second, we need to test how altered disturbance frequencies from the present state may be constructive or destructive in their effects on biogeochemical cycling and nutrient availability. Long-term studies, with repeated sampling of soils and vegetation, will be essential in further developing this framework of biogeochemical response to disturbance.     

Optimising Drug Solubilisation in Amorphous Polymer Dispersions: Rational Selection of Hot-melt Extrusion Processing Parameters

The aim of this article was to construct a T–ϕ phase diagram for a model drug (FD) and amorphous polymer (Eudragit® EPO) and to use this information to understand the impact of how temperature–composition coordinates influenced the final properties of the extrudate. Defining process boundaries and understanding drug solubility in polymeric carriers is of utmost importance and will help in the successful manufacture of new delivery platforms for BCS class II drugs. Physically mixed felodipine (FD)–Eudragit^® EPO (EPO) binary mixtures with pre-determined weight fractions were analysed using DSC to measure the endset of melting and glass transition temperature. Extrudates of 10 wt% FD–EPO were processed using temperatures (110°C, 126°C, 140°C and 150°C) selected from the temperature–composition (T–ϕ) phase diagrams and processing screw speed of 20, 100 and 200rpm. Extrudates were characterised using powder X-ray diffraction (PXRD), optical, polarised light and Raman microscopy. To ensure formation of a binary amorphous drug dispersion (ADD) at a specific composition, HME processing temperatures should at least be equal to, or exceed, the corresponding temperature value on the liquid–solid curve in a F–H T–ϕ phase diagram. If extruded between the spinodal and liquid–solid curve, the lack of thermodynamic forces to attain complete drug amorphisation may be compensated for through the use of an increased screw speed. Constructing F–H T–ϕ phase diagrams are valuable not only in the understanding drug–polymer miscibility behaviour but also in rationalising the selection of important processing parameters for HME to ensure miscibility of drug and polymer.KEY WORDS: DSC, Flory–Huggins theory, hot-melt extrusion, thermal processing     

Ontogeny and Sexual Dimorphism of <Emphasis Type="Italic">Glyptotherium texanum</Emphasis> (Xenarthra,Cingulata) from the Pliocene and Pleistocene (Blancan and Irvingtonian NALMA) of Arizona,New Mexico,and Mexico

North American glyptodonts originated from South American ancestors during the Great American Biotic Interchange no later than early Blancan North American Land Mammal Age (NALMA). A substantial expansion in population samples from the late Blancan 111 Ranch fauna of southeastern Arizona, several late Blancan faunas in New Mexico, and the early Blancan–Irvingtonian faunas of Guanajuato, Mexico, permit, analysis of sexual dimorphism and ontogeny of Glyptotherium texanum Osborn, 1903. Growth of carapacial osteoderms was allometric, including changes of the external sculpturing. Overall anatomy of the carapace changed with growth, with development of distinctive pre-iliac and post-iliac regions in lateral profile of adults. Skulls of adults possess a unique boss on the anterior surface of the descending process of the zygomatic arch that is not present in juveniles. Sexual dimorphism involves differences in anatomy of lateral and posterior osteoderms. Glyptotherium arizonae Gidley, 1926, is a junior synonym of G. texanum. The temporal distribution of G. texanum extends from early Blancan NALMA to Irvingtonian NALMA, with geographical distribution from Central America and Mexico to southern United States.     

Design‐to‐Device Approach Affords Panchromatic Co‐Sensitized Solar Cells

Data‐driven materials discovery has become increasingly important in identifying materials that exhibit specific, desirable properties from a vast chemical search space. Synergic prediction and experimental validation are needed to accelerate scientific advances related to critical societal applications. A design‐to‐device study that uses high‐throughput screens with algorithmic encodings of structure–property relationships is reported to identify new materials with panchromatic optical absorption, whose photovoltaic device applications are then experimentally verified. The data‐mining methods source 9431 dye candidates, which are auto‐generated from the literature using a custom text‐mining tool. These candidates are sifted via a data‐mining workflow that is tailored to identify optimal combinations of organic dyes that have complementary optical absorption properties such that they can harvest all available sunlight when acting as co‐sensitizers for dye‐sensitized solar cells (DSSCs). Six promising dye combinations are shortlisted for device testing, whereupon one dye combination yields co‐sensitized DSSCs with power conversion efficiencies comparable to those of the high‐performance, organometallic dye, N719. These results demonstrate how data‐driven molecular engineering can accelerate materials discovery for panchromatic photovoltaic or other applications.     

Spatial analysis of a hydrocarbon waste-remediating landfarm demonstrates influence of management practices on bacterial and fungal community structure

Cultivation of dedicated soil plots called ‘landfarms' is an effective technology for bioremediation of hydrocarbon waste generated by various industrial practices. To understand the influence of soil conditions on landfarm microbial communities, analysis of bacterial and fungal community structure using next-generation sequencing at different sections and depths was performed across a hydrocarbon-waste landfarm in Regina, Saskatchewan, Canada. While a core set of hydrocarbon-associated bacterial and fungal taxa are present throughout the landfarm, unique bacterial and fungal operational taxonomic units are differentially abundant at sections within the landfarm, which correlate with differences in soil physiochemical properties and management practices. Increased frequency of waste application resulted in strong positive correlations between bacterial community assemblages and elevated amounts of oil, grease and F3 – F4 hydrocarbon fractions. In areas of standing water and lower application of hydrocarbon, microbial community structure correlated with soil pH, trace nutrients and metals. Overall, diversity and structure of bacterial communities remain relatively stable across the landfarm, while in contrast, fungal community structure appears more responsive to soil oxygen conditions. Results are consistent with the hypothesis that years of bioremediation activity have shaped microbial communities; however, several management practices can be undertaken to increase efficiency of remediation, including the removal of standing water and soil tilling across the landfarm.     

Picomolar inhibitors as transition-state probes of 5'-methylthioadenosine nucleosidases.

Transition states can be predicted from an enzyme's affinity to related transition-state analogues. 5'-Methylthioadenosine nucleosidases (MTANs) are involved in bacterial quorum sensing pathways and thus are targets for antibacterial drug design. The transition-state characteristics of six MTANs are compared by analyzing dissociation constants (K(d)) with a small array of representative transition-state analogues. These inhibitors mimic early or late dissociative transition states with K(d) values in the picomolar range. Our results indicate that the K(d) ratio for mimics of early and late transition states are useful in distinguishing between these states. By this criterion, the transition states of Neisseria meningitides and Helicobacter pylori MTANs are early dissociative, whereas Escherichia coli, Staphylococcus aureus, Streptococcus pneumoniae, and Klebsiella pneumoniae MTANs have late dissociative characters. This conclusion is confirmed independently by the characteristic [1'- (3)H] and [1'- (14)C] kinetic isotope effects (KIEs) of these enzymes. Large [1'- (3)H] and unity [1'- (14)C] KIEs are observed for late dissociative transition states, whereas early dissociative states showed close-to-unity [1'- (3)H] and significant [1'- (14)C] KIEs. K d values of various MTANs for individual transition-state analogues provide tentative information about transition-state structures due to varying catalytic efficiencies of enzymes. Comparing K d ratios for mimics of early and late transition states removes limitations inherent to the enzyme and provides a better predictive tool in discriminating between possible transition-state structures.     

A high-density admixture scan in 1,670 African Americans with hypertension

Hypertension (HTN) is a devastating disease with a higher incidence in African Americans than European Americans, inspiring searches for genetic variants that contribute to this difference. We report the results of a large-scale admixture scan for genes contributing HTN risk, in which we screened 1,670 African Americans with HTN and 387 control individuals for regions of the genome with elevated proportion of African or European ancestry. No loci were identified that were significantly associated with HTN. We also searched for evidence of an admixture signal at 40 candidate genes and eight previously reported linkage peaks, but none appears to contribute substantially to the differential HTN risk between African and European Americans. Finally, we observed nominal association at one of the loci detected in the admixture scan of Zhu et al. 2005 (p = 0.016 at 6q24.3 correcting for four hypotheses tested), although we caution that the significance is marginal and the estimated odds ratio of 1.19 per African allele is less than what would be expected from the original report; thus, further work is needed to follow up this locus.     

Structural basis of dimerization and nucleic acid binding of human DBHS proteins NONO and PSPC1

The Drosophila behaviour/human splicing (DBHS) proteins are a family of RNA/DNA binding cofactors liable for a range of cellular processes. DBHS proteins include the non-POU domain-containing octamer-binding protein (NONO) and paraspeckle protein component 1 (PSPC1), proteins capable of forming combinatorial dimers. Here, we describe the crystal structures of the human NONO and PSPC1 homodimers, representing uncharacterized DBHS dimerization states. The structures reveal a set of conserved contacts and structural plasticity within the dimerization interface that provide a rationale for dimer selectivity between DBHS paralogues. In addition, solution X-ray scattering and accompanying biochemical experiments describe a mechanism of cooperative RNA recognition by the NONO homodimer. Nucleic acid binding is reliant on RRM1, and appears to be affected by the orientation of RRM1, influenced by a newly identified ‘β-clasp’ structure. Our structures shed light on the molecular determinants for DBHS homo- and heterodimerization and provide a basis for understanding how DBHS proteins cooperatively recognize a broad spectrum of RNA targets.