Bioactivity and structural properties of chimeric analogs of the starfish SALMFamide neuropeptides S1 and S2

The starfish SALMFamide neuropeptides S1 (GFNSALMFamide) and S2 (SGPYSFNSGLTFamide) are the prototypical members of a family of neuropeptides that act as muscle relaxants in echinoderms. Comparison of the bioactivity of S1 and S2 as muscle relaxants has revealed that S2 is ten times more potent than S1. Here we investigated a structural basis for this difference in potency by comparing the bioactivity and solution conformations (using NMR and CD spectroscopy) of S1 and S2 with three chimeric analogs of these peptides. A peptide comprising S1 with the addition of S2's N-terminal tetrapeptide (Long S1 or LS1; SGPYGFNSALMFamide) was not significantly different to S1 in its bioactivity and did not exhibit concentration-dependent structuring seen with S2. An analog of S1with its penultimate residue substituted from S2 (S1(T); GFNSALTFamide) exhibited S1-like bioactivity and structure. However, an analog of S2 with its penultimate residue substituted from S1 (S2(M); SGPYSFNSGLMFamide) exhibited loss of S2-type bioactivity and structural properties. Collectively, our data indicate that the C-terminal regions of S1 and S2 are the key determinants of their differing bioactivity. However, the N-terminal region of S2 may influence its bioactivity by conferring structural stability in solution. Thus, analysis of chimeric SALMFamides has revealed how neuropeptide bioactivity is determined by a complex interplay of sequence and conformation

Direct and oxidative dehydrogenation of propane: From catalyst design to industrial application

The direct formation of propene from propane is a well-established commercial process, which based on energy consumption, is environmentally preferred to the current large-scale sources of propene from steam cracking and fluid catalytic cracking. Current sources of propane are mostly non-renewable, but the development of technologies to produce renewable “green” propane are gaining traction, which coupled with new catalytic processes will provide the platform to produce green propene. We evaluate the technological and environmental merits of dehydrogenation catalysts. Currently, non-oxidative direct dehydrogenation (DDH) is the only commercialised process, and this is reflected in the high space-time yield commonly reported over the most active Pt or Cr catalysts. However, the formation of coke necessitates multi-reactor cycling to facilitate regeneration. Oxidative dehydrogenation using O2 (ODH-O2) does not suffer from coke formation, but can lead to overoxidation, limiting the yield of propene. While no commercial processes have yet been developed, a promising new class of active and selective ODH-O2 catalysts has emerged which use boron as the active component. The use of CO2 as a soft oxidant (ODH-CO2) has also gained interest due to the environmental advantages of utilising CO2. Although this is an attractive prospect, the propene yields with these catalysts are considerably less active then DDH and ODH-O2 catalysts. Despite significant advances in the past decade, current ODH-CO2 catalysts remain far from displaying the activity levels necessary to be considered for commercial application. The specific requirements of catalyst design for each sub-reaction are discussed and we identify that the balance of acid and base sites on the catalyst surface is of paramount importance. Future catalyst design in DDH and ODH-O2 should focus on improving selectivity to propene, while ODH-CO2 catalysts are limited by their low intrinsic activity. The scarcity of some common catalytic elements is also discussed, with recommendations focusing on more abundant chemical elements. Future research should focus on the low temperature activation of CO2 as a priority. With further research and development of lower energy routes to propene based on the dehydrogenation of sustainably-sourced propane, it should be possible to transform the manufacturing landscape of this key chemical intermediate

The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe

The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay --- these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions. LBNE is conceived around three central components: (1) a new, high-intensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a near neutrino detector just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is approximately 1,300 km from the neutrino source at Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions. With its exceptional combination of experimental configuration, technical capabilities, and potential for transformative discoveries, LBNE promises to be a vital facility for the field of particle physics worldwide, providing physicists from around the globe with opportunities to collaborate in a twenty to thirty year program of exciting science. In this document we provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess.Comment: Major update of previous version. This is the reference document for LBNE science program and current status. Chapters 1, 3, and 9 provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess. 288 pages, 116 figure

The development and validation of a scoring tool to predict the operative duration of elective laparoscopic cholecystectomy

Background: The ability to accurately predict operative duration has the potential to optimise theatre efficiency and utilisation, thus reducing costs and increasing staff and patient satisfaction. With laparoscopic cholecystectomy being one of the most commonly performed procedures worldwide, a tool to predict operative duration could be extremely beneficial to healthcare organisations. Methods: Data collected from the CholeS study on patients undergoing cholecystectomy in UK and Irish hospitals between 04/2014 and 05/2014 were used to study operative duration. A multivariable binary logistic regression model was produced in order to identify significant independent predictors of long (> 90 min) operations. The resulting model was converted to a risk score, which was subsequently validated on second cohort of patients using ROC curves. Results: After exclusions, data were available for 7227 patients in the derivation (CholeS) cohort. The median operative duration was 60 min (interquartile range 45–85), with 17.7% of operations lasting longer than 90 min. Ten factors were found to be significant independent predictors of operative durations > 90 min, including ASA, age, previous surgical admissions, BMI, gallbladder wall thickness and CBD diameter. A risk score was then produced from these factors, and applied to a cohort of 2405 patients from a tertiary centre for external validation. This returned an area under the ROC curve of 0.708 (SE = 0.013, p  90 min increasing more than eightfold from 5.1 to 41.8% in the extremes of the score. Conclusion: The scoring tool produced in this study was found to be significantly predictive of long operative durations on validation in an external cohort. As such, the tool may have the potential to enable organisations to better organise theatre lists and deliver greater efficiencies in care

Cell size of Antarctic phytoplankton as a biogeochemical condition

Two contrasting high nutrient/low chlorophyll regions having different conditions that control phytoplankton production, and separated by an area of blooming, are found during summer in the vicinity of the South Shetland Islands (Antarctica). Low chlorophyll conditions occur either in Fe-rich, deeply mixed and high salinity Weddell Sea shelf waters, or the Fe-poor, shoaled and low salinity Drake Passage Antarctic Circumpolar Current waters, while phytoplankton blooms are located between in mid salinity water. Contrasting phytoplankton communities were found to populate these different biogeochemical provinces. In data from six field seasons (1999–2007), nanoplankton (2–20 μm) were found to be dominant in the phytoplankton populations from light-controlled coastal waters, including blooms, with most chlorophyll found in the 2–5 μm size class. In contrast, the adjacent and presumably Fe-controlled Drake Passage waters were dominated by the microplankton (>20 μm) size class. The asymmetrical distribution of phytoplankton size classes across the salinity gradient, when analysed independently of total chlorophyll concentration, supports the hypothesis that the different food web grazing dynamics are dependent upon biogeochemical provinces

Quantitative microbial ecology off the northern Antarctic Peninsula. Antarctic microbial ecology

The waters surrounding the South Shetland Islands, Antarctica, comprise a coastal/oceanic ecosystem that is iron-fertilized naturally from shelf sources of Weddell Sea origin. My thesis incorporates data from an 18-year time series of hydrographic, chemical and phytoplankton studies carried out during austral summer by the US Antarctic Marine Living Resources program. I show that the South Shetland Islands area is bordered by two contrasting high-nutrient, low-chlorophyll (HNLC) regions, and has an area of phytoplankton blooms that extends eastward from the shelves and shelf breaks surrounding the islands into the central Scotia Sea. As a consequence of low iron concentration, the HNLC region in the northwest sector has low surface chlorophyll concentrations but has a deep chlorophyll maximum (DCM) below the upper mixed layer. The DCM is a result of enhanced production due to elevated iron concentrations in the ferrocline, even though low ambient irradiance (hence light controlled photosynthetic rates) occurs there. The HNLC region in the southeast sector is abundant in nutrients, including iron, but has low chlorophyll concentrations resulting from deeply mixed surface waters to provide low mean ambient irradiances. The phytoplankton blooms in the central and northeast sectors occur where both HNLC sources overlap to result with surface waters having high iron concentrations and shallow mixed layers. This mixing between sources of water is described qualitatively in terms of a salinity gradient, across which the variability in chlorophyll concentration has a unimodal distribution. Maximal concentrations of chlorophyll occur at salinity ~34, and they vary among years as a function of the upper mixed layer depth that is influenced by sea surface temperature. In turn, sea surface temperature appears associated with the atmospheric climate having a global connection through the El Niño Southern Oscillation. The two HNLC areas constitute different biogeochemical provinces, and the phytoplankton community size-class composition changes between them. This change is hypothesized as a result of size-selective vs. non-selective grazing strategies of the different zooplankton assemblages that reside in each of the two provinces

Deep chlorophyll a maxima (DCMs) in pelagic Antarctic waters. II. Relation to bathymetric features and dissolved iron concentrations

A deep chlorophyll a maximum (DCM) at depths between 60 and 90 m in waters south of the Antarctic Polar Front (APF) occurs only in pelagic waters where the chlorophyll a concentrations in the upper mixed layer (UML) are very low (generally <0.2 mg m–³). Dissolved Fe concentrations in these waters with DCMs are also very low (generally <0.2 nM) and are probably a limiting factor for phytoplankton growth and biomass. DCMs occur in the upper portion of the temperature minimum layer (TML), which is the winter residue of the Antarctic Surface Water (AASW). The higher phytoplankton biomass at these depths is thought to result from higher Fe concentrations in the winter remnant of the AASW as compared to that found in the overlying UML. A survey of the literature indicates that DCMs are located predominately over the deep ocean basins where enrichment of surface waters with Fe from either coastal sediments or from upwelling processes would be minimal. DCMs are not found in coastal waters or in pelagic regions where complex bottom topography causes upwelling of deep water with sufficiently high Fe concentrations to enhance surface chlorophyll a concentrations. Such enrichment of surface waters overlying or downstream of topographical seamounts or ridges that rise to within a few thousand meters of the surface usually results in elevated phytoplankton biomass in the UML and no DCM due to decreased solar irradiance in the TML. The effect of such enrichment of Fe in surface pelagic waters that results from upwelling processes is most pronounced in the Scotia Sea, in the Polar Frontal region downstream of South Georgia, over the Southwest Indian Ridge, over the Kerguelen Plateau, and over the Pacific Antarctic and Southeast Indian Ridges

Weddell-Scotia Confluence Effect on the Iron Distribution in Waters Surrounding the South Shetland (Antarctic Peninsula) and South Orkney (Scotia Sea) Islands During the Austral Summer in 2007 and 2008

An oceanographic survey around the South Shetland Islands (SSI) and the South Orkney Islands (SOI) was conducted during January 2007 and February 2008, respectively, as part of the United States Antarctic Marine Living Resources (AMLR) program ecosystems surveys. At 27 stations, concentrations of dissolved labile Fe (DFe) and total acid leachable (unfiltered, TaLFe) iron (Fe) were measured in the upper 200 m (including coastal and oceanic waters) to better resolve the factors limiting primary production in these regions. Northwest of the SSI, a region influenced by Drake Passage (DP) waters, mean DFe (∼0.26 nM) and TaLFe (∼1.02 nM) concentrations were the lowest, whereas intermediate concentrations for both DFe and TaLFe were measured in the Bransfield Strait (BS). Around Elephant Island (EI), over and off the continental shelf, Fe concentrations differed between the west and the east margins. DFe and TaLFe concentrations further support the argument that the effect of the Shackleton Transverse Ridge (STR) is a crucial structure affecting both the Fe and the chlorophyll distributions in this region. The waters around the SOI had DFe concentrations higher than those in the SSI, with the area north of the South Scotia Ridge (SSR) (60°S), having the highest DFe (0.54 nM) concentrations and the waters in Powell Basin (PB) having the lowest DFe (1.17 nM) and TaLFe (4.51 nM) and concentrations. These spatial patterns of Fe suggest that there are different Fe inputs from shelf waters near the Antarctic Slope Front (ASF). The overall TaLFe:DFe ratios, used as indicator for understanding the relative distance of Fe sources, were lower around the SOI compared to those in the SSI, suggesting that the Fe source for SOI waters was more distant. The spatial patterns between Fe and chlorophyll-a (Chl-a) concentrations in relation to the hydrography highlight the complexity and variability of the oceanographic processes in the region. These results improve the knowledge on the Fe sources and inputs in the less known SOI waters during the austral summer, and they further support the importance of advective processes from the Fe-rich waters that flow from the eastern margin of the Antarctic Peninsula (AP) into the Weddell-Scotia Confluence (WSC)

Microbial biogeography during austral summer 2007 in the surface waters around the South Shetland Islands, Antarctica

Recent studies have concluded that different water bodies in the ocean can contain different microbial communities. The goal of the present study was to determine if biogeographic patterns are present for aquatic microbes in waters which meet around the South Shetland Islands (SSI), Antarctica. Prokaryotic and eukaryotic marine microbial communities were monitored during the 2007 austral summer by use of polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE) of small subunit ribosomal DNA. Hydrographic properties, nutrients and chlorophyll a were also measured. There was an onshore to offshore gradient in temperature, salinity and iron concentration and a unimodal distribution of chlorophyll a concentration in relation to the middle of this gradient that occurred near the SSI. The differences in microbial community structure among stations in the studied area were correlated with both geographical distance and environmental factors. For eukaryotes, the correlation was strongest for environment, whereas it was strongest for geographical distance for the prokaryotes. Eukaryotic and prokaryotic community structures were highly correlated. Surface water from the Weddell Sea had a different community of eukaryotes than the water in the Antarctic Circumpolar Current in the Drake Passage, whereas the prokaryotic community was not significantly different. The area close to the SSI where the 2 water types mix had the highest chlorophyll concentration and significantly different communities of eukaryotes and prokaryotes from both of the inflowing water types. These results suggest that the prokaryote community structure was more affected by productivity than by environmental variables

Optimal multiparameter analysis of source water distributions in the Southern Drake Passage

National Science Foundation [ANT0444134, ANT0948338, OCE0957342, OCE0622740]In order to evaluate the effects of horizontal advection on iron supply in the vicinity of the Shackleton Transverse Ridge (SIR) in the southern Drake Passage, the water composition in the region is estimated along the isopycnal containing the subsurface iron peak. Optimal Multiparameter (OMP) analysis of temperature, salinity, oxygen and nutrient data is used to estimate the water composition at CID stations sampled in summer 2004 and winter 2006. The highest iron concentrations in the Ona Basin are found below the mixed layer, both in summer and in winter. The water composition derived from the OMP analysis is consistent with a scenario in which iron-rich shelf waters from the South Shetland Islands and the Antarctic Peninsula are advected northward on the eastern side of the SIR, where they interact with the low-iron waters of the Antarctic Circumpolar Current (ACC) in the Ona Basin. The shelf waters and the ACC waters appear to interact through a stirring process without fully mixing, resulting in a filamented distribution that has also been inferred from the satellite data. To the west of the STR, the shelf waters are primarily confined to the continental shelf, and do not extend northwards. This source of water distribution is consistent with the idea that iron enters the Ona Basin from the continental shelf through advection along an isopycnal, resulting in an iron concentration peak occurring below the winter mixed layer in the Ona Basin. (c) 2012 Elsevier Ltd. All rights reserved