A comparative protease stability study of synthetic macrocyclic peptides that mimic two endocrine hormones

Peptide therapeutics have traditionally faced many challenges including low bioavailability, poor proteolytic stability and difficult cellular uptake. Conformationally constraining the backbone of a peptide into a macrocyclic ring often ameliorates these problems and allows for the development of a variety of new drugs. Such peptide-based pharmaceuticals can enhance the multi-faceted functionality of peptide side chains, permitting the peptides to bind cellular targets and receptors necessary to impart their role, while protecting them from degrading cellular influences. In the work described here, we developed three cyclic peptides, VP mimic1, VP mimic2 and OT mimic1, which mimic endocrine hormones vasopressin and oxytocin. Making notable changes to the overall structure and composition of the parent hormones, we synthesized the mimics and tested their durability against treatment with three proteases chosen for their specificity: pepsin, alpha-chymotrypsin, and pronase. Vasopressin and oxytocin contain a disulfide linkage leaving them particularly vulnerable to deactivation from the reducing environment inside the cell. Thus, we increased the complexity of our assays by adding reducing agent glutathione to each mixture. Subsequently, we discovered each of our mimics withstood protease treatment with less degradation and/or a slower rate of degradation as compared to both parent hormones and a linear control peptide.     

Discovery of an intravenous hepatoselective glucokinase activator for the treatment of inpatient hyperglycemia

Glucokinase (hexokinase IV) continues to be a compelling target for the treatment of type 2 diabetes given the wealth of supporting human genetics data and numerous reports of robust clinical glucose lowering in patients treated with small molecule allosteric activators. Recent work has demonstrated the ability of hepatoselective activators to deliver glucose lowering efficacy with minimal risk of hypoglycemia. While orally administered agents require a considerable degree of passive permeability to promote suitable exposures, there is no such restriction on intravenously delivered drugs. Therefore, minimization of membrane diffusion in the context of an intravenously agent should ensure optimal hepatic targeting and therapeutic index. This work details the identification a hepatoselective GKA exhibiting the aforementioned properties.     

Impacts of inundation and drought on eukaryote biodiversity in semi‐arid floodplain soils

Floodplain ecosystems are characterized by alternating wet and dry phases and periodic inundation defines their ecological character. Climate change, river regulation and the construction of levees have substantially altered natural flooding and drying regimes worldwide with uncertain effects on key biotic groups. In southern Australia, we hypothesized that soil eukaryotic communities in climate change affected areas of a semi‐arid floodplain would transition towards comprising mainly dry‐soil specialist species with increasing drought severity. Here, we used 18S rRNA amplicon pyrosequencing to measure the eukaryote community composition in soils that had been depleted of water to varying degrees to confirm that reproducible transitional changes occur in eukaryotic biodiversity on this floodplain. Interflood community structures (3 years post‐flood) were dominated by persistent rather than either aquatic or dry‐specialist organisms. Only 2% of taxa were unique to dry locations by 8 years post‐flood, and 10% were restricted to wet locations (inundated a year to 2 weeks post‐flood). Almost half (48%) of the total soil biota were detected in both these environments. The discovery of a large suite of organisms able to survive nearly a decade of drought, and up to a year submerged supports the concept of inherent resilience of Australian semi‐arid floodplain soil communities under increasing pressure from climatic induced changes in water availability.     

Using multilevel models to identify drivers of landscape‐genetic structure among management areas

Landscape genetics offers a powerful approach to understanding species' dispersal patterns. However, a central obstacle is to account for ecological processes operating at multiple spatial scales, while keeping research outcomes applicable to conservation management. We address this challenge by applying a novel multilevel regression approach to model landscape drivers of genetic structure at both the resolution of individuals and at a spatial resolution relevant to management (i.e. local government management areas: LGAs) for the koala (Phascolartos cinereus) in Australia. Our approach allows for the simultaneous incorporation of drivers of landscape‐genetic relationships operating at multiple spatial resolutions. Using microsatellite data for 1106 koalas, we show that, at the individual resolution, foliage projective cover (FPC) facilitates high gene flow (i.e. low resistance) until it falls below approximately 30%. Out of six additional land‐cover variables, only highways and freeways further explained genetic distance after accounting for the effect of FPC. At the LGA resolution, there was significant variation in isolation‐by‐resistance (IBR) relationships in terms of their slopes and intercepts. This was predominantly explained by the average resistance distance among LGAs, with a weaker effect of historical forest cover. Rates of recent landscape change did not further explain variation in IBR relationships among LGAs. By using a novel multilevel model, we disentangle the effect of landscape resistance on gene flow at the fine resolution (i.e. among individuals) from effects occurring at coarser resolutions (i.e. among LGAs). This has important implications for our ability to identify appropriate scale‐dependent management actions.     

Holarctic genetic structure and range dynamics in the woolly mammoth

Ancient DNA analyses have provided enhanced resolution of population histories in many Pleistocene taxa. However, most studies are spatially restricted, making inference of species-level biogeographic histories difficult. Here, we analyse mitochondrial DNA (mtDNA) variation in the woolly mammoth from across its Holarctic range to reconstruct its history over the last 200 thousand years (kyr). We identify a previously undocumented major mtDNA lineage in Europe, which was replaced by another major mtDNA lineage 32–34 kyr before present (BP). Coalescent simulations provide support for demographic expansions at approximately 121 kyr BP, suggesting that the previous interglacial was an important driver for demography and intraspecific genetic divergence. Furthermore, our results suggest an expansion into Eurasia from America around 66 kyr BP, coinciding with the first exposure of the Bering Land Bridge during the Late Pleistocene. Bayesian inference indicates Late Pleistocene demographic stability until 20–15 kyr BP, when a severe population size decline occurred.     

5,6-Dihydro-5-aza-2′-deoxycytidine potentiates the anti-HIV-1 activity of ribonucleotide reductase inhibitors

The nucleoside analog 5,6-dihydro-5-aza-2′-deoxycytidine (KP-1212) has been investigated as a first-in-class lethal mutagen of human immunodeficiency virus type-1 (HIV-1). Since a prodrug monotherapy did not reduce viral loads in Phase II clinical trials, we tested if ribonucleotide reductase inhibitors (RNRIs) combined with KP-1212 would improve antiviral activity. KP-1212 potentiated the activity of gemcitabine and resveratrol and simultaneously increased the viral mutant frequency. G-to-C mutations predominated with the KP-1212-resveratrol combination. These observations represent the first demonstration of a mild anti-HIV-1 mutagen potentiating the antiretroviral activity of RNRIs and encourage the clinical translation of enhanced viral mutagenesis in treating HIV-1 infection.     

Bioactive compounds from Stuhlmannia moavi from the Madagascar dry forest

Bioassay-directed fractionation of the leaf and root extracts of the antiproliferative Madagascar plant Stuhlmannia moavi afforded 6-acetyl-5,8-dihydroxy-2-methoxy-7-methyl-1,4-naphthoquinone (stuhlmoavin, 1) as the most active compound, with an IC₅₀ value of 8.1 μM against the A2780 human ovarian cancer cell line, as well as the known homoisoflavonoid bonducellin (2) and the stilbenoids 3,4,5′-trihydroxy-3′-methoxy-trans-stilbene (3), piceatannol (4), resveratrol (5), rhapontigenin (6), and isorhapontigenin (7). The structure elucidation of all compounds was based on NMR and mass spectroscopic data, and the structure of 1 was confirmed by a single crystal X-ray analysis. Compounds 2?5 showed weak A2780 activities, with IC₅₀ values of 10.6, 54.0, 41.0, and 74.0 μM, respectively. Compounds 1?3 also showed weak antimalarial activity against Plasmodium falciparum with IC₅₀ values of 23, 26, and 27 μM, respectively.     

Social life cycle assessment of palm oil biodiesel: a case study in Jambi Province of Indonesia

Purpose

This study aims to investigate the social implications of palm oil biodiesel via a case study using a life cycle assessment framework.

Methods

The case study was conducted in Jambi Province of Indonesia and involved several stakeholders, such as value chain actors, employees, local community members, government, and nongovernmental organization representatives related in palm oil industry. The assessment was carried out using social criteria developed by adopting the Society of Environmental Toxicology and Chemistry/United Nations Environment Programme Code of Practice, supplemented by an expert survey, and supported by literature review. Stakeholders’ perspectives were evaluated by determining the gaps between expected and perceived quality of each social criterion, which are gauged using seven-point Likert scale.

Results and discussion

Twenty-four social criteria were developed and aggregated into five social impact categories: human rights, working condition, cultural heritage, social–economic repercussion, and governance. These criteria have been weighted, useful for further application in multicriteria decision analysis. The results of the stakeholders’ survey reveal the critical social hotspots, which are the issues within the impact categories of working conditions and cultural heritage.

Conclusions

In order to achieve the social equitability of palm oil biodiesel, which is an important pillar to sustainability, efforts must be put to address these social hotspots through actions in various policy level.     

In vivo zinc toxicity phenotypes provide a sensitized background that suggests zinc transport activities for most of the Drosophila Zip and ZnT genes

Members of the ZIP (SLC39A) and ZnT (SLC30A) families of transmembrane domain proteins are predicted to transport the essential transition metal zinc across membranes, regulating cellular zinc content and distribution via uptake and efflux at the outer plasma and organellar membranes. Twenty-four ZIP and ZnT proteins are encoded in mammalian genomes, raising questions of whether all actually transport zinc, whether several function together in the same tissues/cell types, and how the activity of these transporters is coordinated. To address these questions, we have taken advantage of the ability to manipulate several genes simultaneously in targeted cell types in Drosophila. Previously we reported zinc toxicity phenotypes caused by combining overexpression of a zinc uptake gene, dZip42C.1, with suppression of a zinc efflux gene, dZnT63C. Here we show that these phenotypes can be used as a sensitized in vivo system to detect subtle alterations in zinc transport activity that would be buffered in healthy cells. Using two adult tissues, the fly eye and midline (thorax/abdomen), we find that when overexpressed, most of the 17 Drosophila Zip and ZnT genes modify the zinc toxicity phenotypes in a manner consistent with their predicted zinc transport activity. In most cases, we can reconcile that activity with the cellular localization of an enhanced green fluorescent protein tagged version of the protein. Additionally, targeted suppression of each gene by RNA interference reveals several of the fly Zip and ZnT genes are required in the eye, indicating that numerous independent zinc transport genes are acting together in a single tissue.