Towards an Environmental Classification of Lentic Aquatic Ecosystems in the McMurdo Dry Valleys, Antarctica.

The McMurdo Dry Valleys are the largest single ice-free area in Antarctica, and of considerable scientific and conservation value as an extreme polar desert. This is recognised through the McMurdo Dry Valleys Antarctic Specially Managed Area (ASMA), where management's goals focus on protection of its unique features, while facilitating science access. Using a mix of remote sensing and existing cartography, we have identified over 6000 lakes and ponds in the ASMA. This study develops a classification of those aquatic ecosystems to provide a framework for management. It uses a limited top-down, hierarchical classification to define 13 class separations based on physical attributes that could largely be ascribed from existing databases or remotely sensed information. The first hierarchical level was based on landscape position, separating coastal kettle holes (reflecting recent glacial history), from other "topographic" water bodies. The second level was based on endorheic vs exorheic drainage, the third on mid-summer ice condition (no-ice cap; ice capped; frozen to base) and the fourth on source of inflow (glacial or non-glacial). Kettles were sub-classed by mid-summer ice only. Classes were tested against a set of field observations and an expert workshop validation process considered management implications for the ASMA. This study shows how the classification assists our understanding of Dry Valley landscapes and addresses management issues faced by researchers, environmental managers and policy makers. The approach to classification, rather than the detailed classes that may be specific to the Dry Valleys, has potential for wider use in other polar landscapes.

Oil-in-oil pickering emulsions stabilized by diblock copolymer nanoparticles.

HYPOTHESIS: Diblock copolymer nanoparticles have been shown to be Pickering emulsifiers for both oil-in-water and water-in-oil emulsions. Recently, we reported the preparation of sterically-stabilized diblock copolymer spheres in a low-viscosity silicone oil (Macromolecules 53 (2020) 1785-1794). We hypothesized that such spheres could be used as a Pickering emulsifier for a range of oil-in-oil emulsions comprising droplets of a bio-sourced oil dispersed in silicone oil. EXPERIMENTS: Diblock copolymer spheres were prepared via reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization of benzyl methacrylate in silicone oil and characterized by dynamic light scattering and transmission electron microscopy. These spheres were evaluated as Pickering emulsifiers for a series of oil-in-oil Pickering emulsions. The influence of both sphere size and core-forming block composition was investigated. FINDINGS: Optimization of the nanoparticle size and core-forming block composition enabled stable bio-sourced oil-in-silicone emulsions to be obtained for nine out of the ten bio-sourced oils investigated. These emulsions were characterized in terms of their mean droplet size by optical microscopy.

Correction: Glycosylated naphthalimides and naphthalimide Tröger's bases as fluorescent aggregation probes for Con A.

Correction for 'Glycosylated naphthalimides and naphthalimide Tröger's bases as fluorescent aggregation probes for Con A' by Elena Calatrava-Pérez et al., Org. Biomol. Chem., 2019, DOI: 10.1039/c8ob02980f.

Glycosylated naphthalimides and naphthalimide Tröger's bases as fluorescent aggregation probes for Con A.

Herein we report the synthesis of fluorescent, glycosylated 4-amino-1,8-naphthalimide (Nap) 1, and the related 1,8-naphthalimides Tröger's bases (TBNap) 2 and 3, from 1,8-naphthalic anhydride precursors, the α-mannosides being introduced through the use of CuAAC mediated 'click' chemistry. We investigate the photophysical properties of these probes in buffered solution and demonstrate their ability to function as fluorescent probes for Concanavalin A (Con A) lectin. We show that both the Nap and TBNap structures self-assemble in solution. The formation of the resulting supramolecular structures is driven by head-to-tail π-π stacking and extended hydrogen bonding interactions of the Nap and the triazole moieties. These interactions give rise to spherical nano-structures (ca. 260 nm and 100 nm, for 1 and 3, respectively), which interact with the Con-A protein, the interaction being probed by using both luminescent and Scanning Electron Microscopy imaging as well as dynamic light scattering measurements. Finally, we show that these supramolecular assembles can be used as luminescent imaging agents, through confocal fluorescence imaging of HeLa cells of the per-acetylated version 2.

Synthesis, Antiproliferative and Pro-Apoptotic Effects of Nitrostyrenes and Related Compounds in Burkitt's Lymphoma.

BACKGROUND: Cancers of the lymphatic cells (lymphomas) account for approximately 12% of malignant diseases worldwide. The nitrostyrene scaffold is identified as a lead target structure for the development of particularly effective compounds targeting Burkitt's lymphoma (BL). OBJECTIVES: The aims of the curent study were to synthesise a panel of nitrostyrene compounds and to evaluate their activity in Burkitt's lymphoma (BL). METHODS: A panel of structurally varied compounds were designed and synthesised using Henry Knoevenagel condensation reactions. Single crystal X-Ray analysis confirmed the E configuration for six examples of these novel structures. A number of nitrostyrene-related compounds were also investigated including 1,3-bis(aryl)-2-nitropropenes together with heterocyclic scaffolds containing the nitrovinyl pharmacophore such as 3-nitro-2-phenyl-2H-chromenes. The antiproliferative activities of the compounds were evaluated using the BL cell lines EBV- MUTU-1 and EBV+ DG- 75 (chemoresistant) to establish preliminary structure-activity relationships. RESULTS: Lead compounds with optimized nitrostyrene scaffolds and 3-nitro-2-phenyl-2Hchromene structures were successfully established with typical IC50 values of 0.45 µM and 0.47 µM in MUTU-1 cells and 1.41 µM and 1.92 µM, respectively, in DG-75 cells. The mechanism of cell death was identified as apoptotic and the lead compound was found to elicit comparable apoptotic effects to Taxol in Burkitt's lymphoma cell lines MUTU-1 and DG-75. CONCLUSION: This class of pharmaceutically active compounds with potential for the treatment of Burkitt`s lymphoma suggest a potential role for nitrostyrene based agents in chemotherapy.

Bespoke contrast-matched diblock copolymer nanoparticles enable the rational design of highly transparent Pickering double emulsions.

We report the preparation of highly transparent oil-in-water Pickering emulsions using contrast-matched organic nanoparticles. This is achieved via addition of judicious amounts of either sucrose or glycerol to an aqueous dispersion of poly(glycerol monomethacrylate)56-poly(2,2,2-trifluoroethyl methacrylate)500 [PGMA-PTFEMA] diblock copolymer nanoparticles prior to high shear homogenization with an equal volume of n-dodecane. The resulting Pickering emulsions comprise polydisperse n-dodecane droplets of 20-100 µm diameter and exhibit up to 96% transmittance across the visible spectrum. In contrast, control experiments using non-contrast-matched poly(glycerol monomethacrylate)56-poly(benzyl methacrylate)300 [PGMA56-PBzMA300] diblock copolymer nanoparticles as a Pickering emulsifier only produced conventional highly turbid emulsions. Thus contrast-matching of the two immiscible phases is a necessary but not sufficient condition for the preparation of highly transparent Pickering emulsions: it is essential to use isorefractive nanoparticles in order to minimize light scattering. Furthermore, highly transparent oil-in-water-in-oil Pickering double emulsions can be obtained by homogenizing the contrast-matched oil-in-water Pickering emulsion prepared using the PGMA56-PTFEMA500 nanoparticles with a contrast-matched dispersion of hydrophobic poly(lauryl methacrylate)39-poly(2,2,2-trifluoroethyl methacrylate)800 [PLMA39-PTFEMA800] diblock copolymer nanoparticles in n-dodecane. Finally, we show that an isorefractive oil-in-water Pickering emulsion enables fluorescence spectroscopy to be used to monitor the transport of water-insoluble small molecules (pyrene and benzophenone) between n-dodecane droplets. Such transport is significantly less efficient than that observed for the equivalent isorefractive surfactant-stabilized emulsion. Conventional turbid emulsions do not enable such a comparison to be made because the intense light scattering leads to substantial spectral attenuation.

Development of novel cyclic peptides as pro-apoptotic agents.

Our recent finding that paclitaxel behaves as a peptidomimetic of the endogenous protein Nur77 inspired the design of two peptides (PEP1 and PEP2) reproducing the effects of paclitaxel on Bcl-2 and tubulin, proving the peptidomimetic nature of paclitaxel. Starting from these peptide-hits, we herein describe the synthesis and the biological investigation of linear and cyclic peptides structurally related to PEP2. While linear peptides (2a,b, 3a,b, 4, 6a-f) were found inactive in cell-based assays, biological analysis revealed a pro-apoptotic effect for most of the cyclic peptides (5a-g). Cellular permeability of 5a (and also of 2a,b) on HL60 cells was assessed through confocal microscopy analysis. Further cellular studies on a panel of leukemic cell lines (HL60, Jurkat, MEC, EBVB) and solid tumor cell lines (breast cancer MCF-7 cells, human melanoma A375 and 501Mel cells, and murine melanoma B16F1 cells) confirmed the pro-apoptotic effect of the cyclic peptides. Cell cycle analysis revealed that treatment with 5a, 5c, 5d or 5f resulted in an increase in the number of cells in the sub-G0/G1 peak. Direct interaction with tubulin (turbidimetric assay) and with microtubules (immunostaining experiments) was assessed in vitro for the most promising compounds.

Unconventional Knoevenagel-type indoles: Synthesis and cell-based studies for the identification of pro-apoptotic agents.

A new series of indole-based analogues were recently identified as potential anticancer agents. The Knoevenagel-type indoles herein presented were prepared via a one-pot condensation of iminium salts with active methylene reagents and were isolated as single geometric isomers. Biological evaluation in different cell-based assays revealed an antiproliferative activity for some analogues already in the nanomolar range against leukaemia, breast and renal cancer cell lines. To explain these effects, the most promising analogues of the series were engaged in further cell-based studies. Compounds 5e, l, p and 6a, b highlighted a pro-apoptotic potential being able to induce apoptosis in HL60, K562 and MCF-7 cell lines in a dose and time-dependent manner. The ability of these compounds to arrest cell cycle at the G2/M phase inspired the immunofluorescence studies which allowed us to identify tubulin as a potential target for compounds 5l and 6b.

Enhancing microalgal photosynthesis and productivity in wastewater treatment high rate algal ponds for biofuel production.

With microalgal biofuels currently receiving much attention, there has been renewed interest in the combined use of high rate algal ponds (HRAP) for wastewater treatment and biofuel production. This combined use of HRAPs is considered to be an economically feasible option for biofuel production, however, increased microalgal productivity and nutrient removal together with reduced capital costs are needed before it can be commercially viable. Despite HRAPs being an established technology, microalgal photosynthesis and productivity is still limited in these ponds and is well below the theoretical maximum. This paper critically evaluates the parameters that limit microalgal light absorption and photosynthesis in wastewater HRAPs and examines biological, chemical and physical options for improving light absorption and utilisation, with the view of enhancing biomass production and nutrient removal.

Modifying the high rate algal pond light environment and its effects on light absorption and photosynthesis.

The combined use of high rate algal ponds (HRAPs) for wastewater treatment and commercial algal production is considered to be an economically viable option. However, microalgal photosynthesis and biomass productivity is constrained in HRAPs due to light limitation. This paper investigates how the light climate in the HRAP can be modified through changes in pond depth, hydraulic retention time (HRT) and light/dark turnover rate and how this impacts light absorption and utilisation by the microalgae. Wastewater treatment HRAPs were operated at three different pond depth and HRT during autumn. Light absorption by the microalgae was most affected by HRT, significantly decreasing with increasing HRT, due to increased internal self-shading. Photosynthetic performance (as defined by Pmax, Ek and α), significantly increased with increasing pond depth and decreasing HRT. Despite this, increasing pond depth and/or HRT, resulted in decreased pond light climate and overall integrated water column net oxygen production. However, increased light/dark turnover was able to compensate for this decrease, bringing the net oxygen production in line with shallower ponds operated at shorter HRT. On overcast days, modelled daily net photosynthesis significantly increased with increased light/dark turnover, however, on clear days such increased turnover did not enhance photosynthesis. This study has showed that light absorption and photosynthetic performance of wastewater microalgae can be modified through changes to pond depth, HRT and light/dark turnover.

The effects of CO2 addition along a pH gradient on wastewater microalgal photo-physiology, biomass production and nutrient removal.

Carbon limitation in domestic wastewater high rate algal ponds is thought to constrain microalgal photo-physiology and productivity, particularly in summer. This paper investigates the effects of CO2 addition along a pH gradient on the performance of wastewater microalgae in high rate algal mesocosms. Performance was measured in terms of light absorption, electron transport rate, photosynthetic efficiency, biomass production and nutrient removal efficiency. Light absorption by the microalgae increased by up to 128% with increasing CO2 supply, while a reduction in the package effect meant that there was less internal self-shading thereby increasing the efficiency of light absorption. CO2 augmentation increased the maximum rate of both electron transport and photosynthesis by up to 256%. This led to increased biomass, with the highest yield occurring at the highest dissolved inorganic carbon/lowest pH combination tested (pH 6.5), with a doubling of chlorophyll-a (Chl-a) biomass while total microalgal biovolume increased by 660% in Micractinium bornhemiense and by 260% in Pediastrum boryanum dominated cultures. Increased microalgal biomass did not off-set the reduction in ammonia volatilisation in the control and overall nutrient removal was lower with CO2 than without. Microalgal nutrient removal efficiency decreased as pH decreased and may have been related to decreased Chl-a per cell. This experiment demonstrated that CO2 augmentation increased microalgal biomass in two distinct communities, however, care must be taken when interpreting results from standard biomass measurements with respect to CO2 augmentation.

The UK's Surplus Source Disposal Programme: successful management of a national radioactive legacy.

Between 2004 and 2009, the Surplus Source Disposal Programme (SSDP) arranged and subsidised the safe disposal or recycling of more than 11,000 unwanted radioactive items containing in total more than 8.5 x 10(14) Bq of activity, from some 500 sites throughout the United Kingdom. Sources were removed principally from universities, schools and colleges, museums, and hospitals. SSDP was funded by the UK Government and managed by the Environment Agency. The programme was delivered at a total cost of pound sterling 7.14 million, nearly pound sterling 2 million less than its initial budget. This was a big success for health and safety, the environment, business and the public purse. Current legislative requirements under the High Activity Sealed Sources Directive, which came into effect during 2005, will prevent a build-up of high activity surplus sources in future. Continuing vigilance may be needed to avoid a build-up of lower activity disused sources.

Problems in the metabolic evaluation of renal stone disease: audit of intra-individual variation in urine metabolites.

Preliminary metabolic assessment of patients with renal stones includes measurement of urine metabolites. This paper reports on the degree of intra-individual variation in some key urine metabolites. Over 80 medically untreated patients under initial metabolic investigation were audited from whom 24-h urine results were available as three separate urine pairs collected at intervals not less than 1 month apart. Ranking patients by intra-individual variation, above the 75th centile, the highest calcium was at least 216% of the lowest calcium, the respective figures for phosphate, urate, oxalate, citrate, creatinine and sodium were 207, 190, 271, 412, 175 and 233%. In order to estimate pre-treatment excretion within 30% of a true mean at the 95% confidence limit, for calcium and oxalate, the number of 24-h samples required were 3 and 4 respectively with 6 and 9 required to be within 20%. These observations illustrate significant practical clinical problems in assessing patients with renal stones when assessing these basic parameters. Regimens based on small numbers of urine collections are flawed, hence evidence based protocols should be devised. A minimum of three pairs of 24-h urine samples based upon predicting metabolite output within 20-30% or less of the true mean is recommended.

Birth defects and anti-heat shock protein 70 antibodies in early pregnancy.

Abstract It has been suggested that induction of the heat shock response in the mammalian embryo during the critical period of organogenesis can result in anatomical malformation. We measured serum heat shock protein 70 (Hsp70), anti-Hsp70, and anti-Hsp60 in samples taken from expectant mothers at 16 weeks gestation. Samples from women whose babies were born with a birth defect (n = 30) were compared with controls who gave birth to healthy babies (n = 46). Anti-Hsp70 levels were significantly elevated in patients who later gave birth to babies with cleft lip or palate or neurological abnormalities (n = 10): 260 (223-406) microg/mL compared to 150 (88-207) microg/mL in controls (P < 0.001). No significant differences were found in serum Hsp70 and anti-Hsp60 levels between cases and controls. This finding of increased maternal anti-Hsp70 in patients who later gave birth to babies with these abnormalities suggests a previous stressful event may have contributed to the pathogenesis. Further work is required to determine whether Hsp70 has a direct or indirect role in this pathogenesis or whether anti-Hsp70 is simply a marker of a prior increase in Hsp70 due to a physiological stress that itself resulted in the damage. This work is consistent with previous studies showing a buffering role for Hsps in evolution.

Partitioning of the serotonin transporter into lipid microdomains modulates transport of serotonin.

The serotonin transporter (SERT) is an integral membrane protein responsible for the clearance of serotonin from the synaptic cleft following the release of the neurotransmitter. SERT plays a prominent role in the regulation of serotoninergic neurotransmission and is a molecular target for multiple antidepressants as well as substances of abuse. Here we show that SERT associates with lipid rafts in both heterologous expression systems and rat brain and that the inclusion of the transporter into lipid microdomains is critical for serotonin uptake activity. SERT is present in a subpopulation of lipid rafts, which is soluble in Triton X-100 but insoluble in other non-ionic detergents such as Brij 58. Disaggregation of lipid rafts upon depletion of cellular cholesterol results in a decrease of serotonin transport capacity (V(max)), due to the reduction of turnover number of serotonin transport. Our data suggest that the association of SERT with lipid rafts may represent a mechanism for regulating the transporter activity and, consequently, serotoninergic signaling in the central nervous system, through the modulation of the cholesterol content in the cell membrane. Furthermore, SERT-containing rafts are detected in both intracellular and cell surface fractions, suggesting that raft association may be important for trafficking and targeting of SERT.

Folate supplementation reduces serum hsp70 levels in patients with type 2 diabetes.

Type 2 diabetes patients are subject to oxidative stress as a result of hyperglycemia. The aim of this study was to determine whether administration of the antioxidant folic acid, previously shown to reduce homocysteine levels, would reduce circulating levels of Hsp70 while improving the condition of type 2 diabetes patients with microalbuminuria. Plasma homocysteine fell from pretreatment values of 12.9 to 10.3 microM (P < 0.0001). The urine albumin-creatinine ratio fell from 12.4 to 10.4 mg/mM (P = 0.38). Pretreatment Hsp70 levels were higher in patients not taking insulin (5.32 ng/mL) compared with those on insulin (2.44 ng/mL) (P = 0.012). Folic acid supplementation resulted in a significant fall in Hsp70 (5.32 to 2.05 ng/mL) (P = 0.004). There was no change in Hsp70 in those receiving insulin. Folic acid supplementation in non-insulin-treated type 2 diabetes patients, therefore, resulted in a fall in Hsp70, reflecting an improvement in oxidative stress. The data shows that improvement in homocysteine status can lead to a reduction in Hsp70, indicating the possibility of its use as a marker for severity of disease.

Synthesis of new molecular probes for investigation of steroid biosynthesis induced by selective interaction with peripheral type benzodiazepine receptors (PBR).

In the present study, we have synthesized and tested novel pyridopyrrolo- and pyrrolobenzoxazepine derivatives, as novel and selective peripheral type benzodiazepine receptor (PBR) ligands, and their ability to modulate steroid biosynthesis has been investigated. A subset of new ligands bind the PBR (rat brain and testis) with picomolar affinity, representing the most potent ligands that have been identified to date, and elicited effects on endogenous rate of steroidogenesis in MA10 Leydig cells, having similar potency and effect as PK11195. Several compounds, differently substituted at C-7, were used as molecular yardsticks to probe the spatial dimension of the lipophilic pocket L4 in the receptor binding site.