Site selective C–H functionalization of Mitragyna alkaloids reveals a molecular switch for tuning opioid receptor signaling efficacy

Mitragynine (MG) is an indole alkaloid from kratom plant that binds opioid receptors and as such presents a scaffold for the development of atypical opioid receptor modulators. Here, the authors report a synthetic method for selective functionalization of the C11 position of MG, and show that this position is essential for fine-tuning opioid receptor signaling efficacy

Lipoprotein lipase is active as a monomer

Lipoprotein lipase (LPL), the enzyme that hydrolyzes triglycerides in plasma lipoproteins, is assumed to be active only as a homodimer. In support of this idea, several groups have reported that the size of LPL, as measured by density gradient ultracentrifugation, is ∼110 kDa, twice the size of LPL monomers (∼55 kDa). Of note, however, in those studies the LPL had been incubated with heparin, a polyanionic substance that binds and stabilizes LPL. Here we revisited the assumption that LPL is active only as a homodimer. When freshly secreted human LPL (or purified preparations of LPL) was subjected to density gradient ultracentrifugation (in the absence of heparin), LPL mass and activity peaks exhibited the size expected of monomers (near the 66-kDa albumin standard). GPIHBP1-bound LPL also exhibited the size expected for a monomer. In the presence of heparin, LPL size increased, overlapping with a 97.2-kDa standard. We also used density gradient ultracentrifugation to characterize the LPL within the high-salt and low-salt peaks from a heparin-Sepharose column. The catalytically active LPL within the high-salt peak exhibited the size of monomers, whereas most of the inactive LPL in the low-salt peak was at the bottom of the tube (in aggregates). Consistent with those findings, the LPL in the low-salt peak, but not that in the high-salt peak, was easily detectable with single mAb sandwich ELISAs, in which LPL is captured and detected with the same antibody. We conclude that catalytically active LPL can exist in a monomeric state

Tumor and Microenvironment Evolution during Immunotherapy with Nivolumab.

The mechanisms by which immune checkpoint blockade modulates tumor evolution during therapy are unclear. We assessed genomic changes in tumors from 68 patients with advanced melanoma, who progressed on ipilimumab or were ipilimumab-naive, before and after nivolumab initiation (CA209-038 study). Tumors were analyzed by whole-exome, transcriptome, and/or T cell receptor (TCR) sequencing. In responding patients, mutation and neoantigen load were reduced from baseline, and analysis of intratumoral heterogeneity during therapy demonstrated differential clonal evolution within tumors and putative selection against neoantigenic mutations on-therapy. Transcriptome analyses before and during nivolumab therapy revealed increases in distinct immune cell subsets, activation of specific transcriptional networks, and upregulation of immune checkpoint genes that were more pronounced in patients with response. Temporal changes in intratumoral TCR repertoire revealed expansion of T cell clones in the setting of neoantigen loss. Comprehensive genomic profiling data in this study provide insight into nivolumab\u27s mechanism of action

Acute-Phase-HDL Remodeling by Heparan Sulfate Generates a Novel Lipoprotein with Exceptional Cholesterol Efflux Activity from Macrophages

During episodes of acute-inflammation high-density lipoproteins (HDL), the carrier of so-called good cholesterol, experiences a major change in apolipoprotein composition and becomes acute-phase HDL (AP-HDL). This altered, but physiologically important, HDL has an increased binding affinity for macrophages that is dependent on cell surface heparan sulfate (HS). While exploring the properties of AP-HDL∶HS interactions we discovered that HS caused significant remodeling of AP-HDL. The physical nature of this change in structure and its potential importance for cholesterol efflux from cholesterol-loaded macrophages was therefore investigated. In the presence of heparin, or HS, AP-HDL solutions at pH 5.2 became turbid within minutes. Analysis by centrifugation and gel electrophoresis indicated that AP-HDL was remodeled generating novel lipid poor particles composed only of apolipoprotein AI, which we designate β2. This remodeling is dependent on pH, glycosaminoglycan type, is promoted by Ca2+ and is independent of protease or lipase activity. Compared to HDL and AP-HDL, remodeled AP-HDL (S-HDL-SAA), containing β2 particles, demonstrated a 3-fold greater cholesterol efflux activity from cholesterol-loaded macrophage. Because the identified conditions causing this change in AP-HDL structure and function can exist physiologically at the surface of the macrophage, or in its endosomes, we postulate that AP-HDL contains latent functionalities that become apparent and active when it associates with macrophage cell surface/endosomal HS. In this way initial steps in the reverse cholesterol transport pathway are focused at sites of injury to mobilize cholesterol from macrophages that are actively participating in the phagocytosis of damaged membranes rich in cholesterol. The mechanism may also be of relevance to aspects of atherogenesis

Plants in aquatic ecosystems: current trends and future directions

Aquatic plants fulfil a wide range of ecological roles, and make a substantial contribution to the structure, function and service provision of aquatic ecosystems. Given their well-documented importance in aquatic ecosystems, research into aquatic plants continues to blossom. The 14th International Symposium on Aquatic Plants, held in Edinburgh in September 2015, brought together 120 delegates from 28 countries and six continents. This special issue of Hydrobiologia includes a select number of papers on aspects of aquatic plants, covering a wide range of species, systems and issues. In this paper we present an overview of current trends and future directions in aquatic plant research in the early 21st century. Our understanding of aquatic plant biology, the range of scientific issues being addressed and the range of techniques available to researchers have all arguably never been greater; however, substantial challenges exist to the conservation and management of both aquatic plants and the ecosystems in which they are found. The range of countries and continents represented by conference delegates and authors of papers in the special issue illustrate the global relevance of aquatic plant research in the early 21st century but also the many challenges that this burgeoning scientific discipline must address

31st Annual Meeting and Associated Programs of the Society for Immunotherapy of Cancer (SITC 2016) : part two

Background The immunological escape of tumors represents one of the main ob- stacles to the treatment of malignancies. The blockade of PD-1 or CTLA-4 receptors represented a milestone in the history of immunotherapy. However, immune checkpoint inhibitors seem to be effective in specific cohorts of patients. It has been proposed that their efficacy relies on the presence of an immunological response. Thus, we hypothesized that disruption of the PD-L1/PD-1 axis would synergize with our oncolytic vaccine platform PeptiCRAd. Methods We used murine B16OVA in vivo tumor models and flow cytometry analysis to investigate the immunological background. Results First, we found that high-burden B16OVA tumors were refractory to combination immunotherapy. However, with a more aggressive schedule, tumors with a lower burden were more susceptible to the combination of PeptiCRAd and PD-L1 blockade. The therapy signifi- cantly increased the median survival of mice (Fig. 7). Interestingly, the reduced growth of contralaterally injected B16F10 cells sug- gested the presence of a long lasting immunological memory also against non-targeted antigens. Concerning the functional state of tumor infiltrating lymphocytes (TILs), we found that all the immune therapies would enhance the percentage of activated (PD-1pos TIM- 3neg) T lymphocytes and reduce the amount of exhausted (PD-1pos TIM-3pos) cells compared to placebo. As expected, we found that PeptiCRAd monotherapy could increase the number of antigen spe- cific CD8+ T cells compared to other treatments. However, only the combination with PD-L1 blockade could significantly increase the ra- tio between activated and exhausted pentamer positive cells (p= 0.0058), suggesting that by disrupting the PD-1/PD-L1 axis we could decrease the amount of dysfunctional antigen specific T cells. We ob- served that the anatomical location deeply influenced the state of CD4+ and CD8+ T lymphocytes. In fact, TIM-3 expression was in- creased by 2 fold on TILs compared to splenic and lymphoid T cells. In the CD8+ compartment, the expression of PD-1 on the surface seemed to be restricted to the tumor micro-environment, while CD4 + T cells had a high expression of PD-1 also in lymphoid organs. Interestingly, we found that the levels of PD-1 were significantly higher on CD8+ T cells than on CD4+ T cells into the tumor micro- environment (p < 0.0001). Conclusions In conclusion, we demonstrated that the efficacy of immune check- point inhibitors might be strongly enhanced by their combination with cancer vaccines. PeptiCRAd was able to increase the number of antigen-specific T cells and PD-L1 blockade prevented their exhaus- tion, resulting in long-lasting immunological memory and increased median survival

Survival of the exotic Chinese mystery snail (Cipangopaludina chinensis malleata) during air exposure and implications for overland dispersal by boats

The exotic Chinese mystery snail (Cipangopaludina chinensis malleata) has invaded lakes and rivers across North America and is particularly widespread in northern Wisconsin. Although deliberate introductions and aquarium releases have likely been important, recreational boats may speed the spread of this snail into lakes. Prior research indicated boater access to be a significant predictor of invasion by C. chinensis and other invasive species in Wisconsin. To mimic the process of boater transport between lakes, I examined the tolerance of juvenile C. chinensis to air exposure in a series of field and laboratory experiments. Field experiments under mesic conditions indicated that this snail can survive exposure to air for at least 4 weeks. Larger juveniles were more resistant than smaller juveniles, an effect that was also observed in the laboratory during short-term (3–14 days) experiments. Tolerance of small juveniles to air exposure appeared to be unaffected by temperature, but was affected by humidity, with higher survival at 64% than 34% relative humidity (RH). Results from the current study suggest that C. chinensis is highly resistant to air exposure and could be readily transported by boats moving between lakes, particularly in cool mesic environments. Since juvenile C. chinensis are common around the roots of emergent macrophytes, hitchhiking with boats should be particularly common with boats or trailers infested with aquatic plants

Mechanisms, effects, and scales of dispersal in freshwater zooplankton

The distribution of organisms can be regulated by local environmental factors and regional processes such as dispersal. Here, we review recent work on the role of dispersal for generating population and community structure in freshwater zooplankton. We examine evidence for different mechanisms of dispersal among lakes, for the effects of dispersal limitations on populations and communities, and for the effects of spatial scale on dispersal rates. Zooplankton move via human or animal vectors, flowing surface waters, and wind; the relative importance of the different modes of transport is poorly understood. Several lines of evidence suggest that dispersal among lakes separated over short spatial scales (\u3c10 km) is sufficiently rapid that local interactions should limit species diversity and composition more than the supply of colonists. However, dispersal limitation over broad scales (tens to thousands of kilometers) might constrain geographic ranges and influence community structure. The current explosion in the incidence of exotic species indicates that such global‐ or continental‐scale dispersal was limiting in the past. The spread of exotic species also provides opportunities to study the scale dependence of zooplankton dispersal. We show how patterns of range expansion can be used to estimate the change in invasion likelihood with distance to a source population. Such dispersal functions provide a crucial link between small‐scale experimental studies and broad‐scale geographic patterns

Hydrology And Local Environmental Factors Influencing Zooplankton Communities In Floodplain Ponds

Wetlands in the floodplains of flood-control impoundments are exposed to different hydrologic conditions than those in natural systems. To gain insight into the impact of hydrology on wetland communities, we examined associations between crustacean zooplankton community structure and hydrologic and local environmental characteristics in 29 ponds surrounding a flood-control reservoir. Fifty-eight species of zooplankton were detected among all ponds, and local species richness ranged from 3-16. Depth and distance from the lake were the most important predictors of species richness and provided 31% of the explanation for variation among ponds. Non-metric multidimensional scaling (NMDS) provided visualization of factors important to community structure. Analysis of similarities revealed hydroperiod and flood frequency were significant factors structuring communities. These results suggest that hydrology has a significant effect on both species richness and community structure of zooplankton communities in floodplain ponds. Elucidating the importance of hydrology to wetlands residing in managed floodplains should assist reservoir managers in understanding the impacts of different management regimes on regional ecology. © 2007, The Society of Wetland Scientists

Spatial disconnection of plankton dynamics in an Ozark reservoir

This two-year study examined spatial distribution and seasonal population dynamics of algae and zooplankton in Table Rock Lake (Missouri, USA), a large clear reservoir threatened by increased development in the watershed. Regular samples were collected from a polymictic up-lake site (10 m deep, mean Secchi transparency 1.0 m) and a monomictic down-lake site (37 m deep, 4.0 m Secchi) in the productive James River arm. Average abundance and biovolume of most algae groups showed no statistically-discernable difference between these two sites, and maximum cell densities were similar in magnitude (∼ 105 cells/mL). Exceptional were the chlorophytes, which had their highest abundance up-lake. Based on taxonomic composition, both sites appear to be dominated by pelagic algae, with little evidence of riverine immigrants. Algae and zooplankton showed rapid seasonal changes in total densities and composition, and peak abundances showed no association in time between the two sites. Although no floating or suspended colonies were ever visible in the field, cyanobacteria (particularly Oscillatoria) were common at both study sites, and we found numerous genera linked to nuisance blooms in other lakes. Zooplankton communities differed between sites, with cladocerans common in winter and spring at the down-lake site and rotifers common year round at the up-lake site. Important cladoceran grazers, such as Daphnia, were usually not abundant; however, when they were common, algae abundance was always low